United States
Environmental Protection
Agency
Office of Emergency and
Remedial Response
Emergency Response- Division
Environmental
Response
Team
rxEPA
Treatment Technologies
for Superfund
Hazardous Materials Incident Response
Training Program
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9285.9-30
EPA/540/R-95/056
PB95-963237
FOREWORD
This manual is for reference use of students enrolled in scheduled training courses of the U.S.
Environmental Protection Agency (EPA). While it will be useful to anyone who needs information
on the subjects covered, it will have its greatest value as an adjunct to classroom presentations
involving discussions among the students and the instructional staff.
This manual has been developed with a goal of providing the best available current information,
individual instructors may provide additional material to cover special aspects of their presentations.
Because of the limited availability of the manual, it should not be cited in bibliographies or other
publications.
References to products and manufacturers are for illustration only; they do not imply endorsement
by EPA.
Constructive suggestions for improvement of the content and format of the manual are welcome.
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TREATMENT TECHNOLOGIES FOR SUPERFUND
(165.3)
4 Days
This introductory-level course provides participants with an overview of the treatment technologies
most frequently used for cleanups at uncontrolled waste sites. The emphasis of the course is on the
selection of appropriate treatment technologies, rather than on the design of such systems. It is
intended for new on-scene coordinators, remedial project managers, waste site managers, and other
personnel interested in treatment technologies.
Topics that are discussed include chemical and physical characteristics, general response actions,
waste treatability, bulking, groundwater treatment, separation techniques, soil vapor extraction, air
and steam stripping, carbon adsorption, inorganic treatment, biological treatment units, thermal
treatment units, and emerging treatment technologies.
Training methods include lectures and group problem-solving exercises. Case studies are used to
demonstrate applications of the treatment technologies. Group discussions relevant to the course are
encouraged.
After completing the course, participants will be able to:
• Describe the tiers of a treatability study
• Identify the processes and explain the limitations of the most frequently used treatment
technologies
• Explain the principles and applications of biological treatment
• Describe two types of incinerator design
• Identify references that describe emerging treatment technologies.
in
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CONTENTS
Section 1
Section 2
Section 3
Section 4
Section 5
Section 6
Section 7
Section 8
Section 9
Section 10
Section 11
Section 12
Section 13
Section 14
Section 15
Standard Orientation and Introduction
Superfund and the National Contingency Plan
Physical and Chemical Characteristics
General Response Actions
Technology Screening
Groundwater Treatment
Volatilization
Carbon Adsorption
Aqueous Biological Treatment
Chemical Reactions and Separation
Bioremediation for Soils and Sludges
Soil Washing and Solvent Extraction
Thermal Treatments
, Immobilization
Alternative Treatments
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ACRONYMS AND ABBREVIATIONS
A
AA
AA
AAQCD
ACGIH
ACHP
ACL
AGO
ADI
AEA
AG
AHERA
AHPA
AIC
AIHA
AIRFA
AIS
AL
ALJ
ANPRM
ANSI
AO
AOC
AOC
APA
APA
AQCR
AQMD
AQUIRE
ARAR
ARCS
ARPA
AT
ATSDR
AWQC
AWQCD
B
BACT
BAT(EA)
BCPCT
BCT
BDAT
BLM
BM
absorption coefficient
atomic absorption
Assistant Administrator (EPA)
Ambient Air Quality Criteria Document (EPA, CAA)
American Conference of Governmental Industrial Hygienists
Advisory Council on Historic Preservation
alternate concentration limit (EPA, RCRA)
administrative consent order
acceptable daily intake (EPA)
Atomic Energy Act (NRC, ERDA, DOE)
Attorney General
Asbestos Hazard Emergency Response Act (EPA, TSCA)
Archaeological and Historical Preservation Act
acceptable intake for chronic exposure (EPA)
American Industrial Hygiene Association
American Indian Religious Freedom Act
acceptable intake for subchronic exposure (EPA)
action level (EPA)
administrative law judge
advance notice of proposed rulemaking
American National Standards Institute
administrative order
area of contamination
area of concern
Administrative Procedure Act
Acid Precipitation Act
air quality control region
air quality management district
acute aquatic toxicity values database (CIS)
applicable or relevant and appropriate requirements
Alternative Remedial Contracting Strategy
Archaeological Resources Protection Act
averaging time
Agency for Toxic Substances and Disease Registry
Ambient Water Quality Criteria (EPA, CWA)
Ambient Water Quality Criteria Document (EPA, CWA)
body weight of receptor
best available control technology (EPA, CAA)
best available technology (economically achievable) (EPA, CWA)
best conventional pollutant control technology (EPA, CAA)
best conventional technology (EPA, CWA)
best demonstrated available technology (EPA, RCRA)
Bureau of Land Management (DOI)
Bureau of Mines
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Acronyms and Abbreviations
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BMP
BOD
BPATT
BPJ
BPT(CA)
BRA
BQRA
BTC
BTEX
BTX
C
C
CA
CAA
CA/FO
CAG
CAMU
CAP
CAP
CAPA
CATEX
CCRIS
CDC
CERCLA
CERCLIS
CERI
CESARS
CEQ
CESQG
CFC
CFR
CHEMID
CHEMLINE
CHEMTRAC
CHEMTREC
CHRIS
CHS
CIL
CIS
CMA
CMI
CMS
CO
CO
COD
COE
CP
best management practices
biochemical (or biological) oxygen demand
best practicable available technology
best professional judgment
best practicable technology (currently available) (EPA, CWA)
baseline risk assessment
baseline quantitative risk assessment
briefly tolerable concentration (NRC)
benzene, toluene, ethylbenzene, and xylenes
benzene, toluene, and xylenes
corrosivity hazardous waste code (EPA, RCRA)
concentration of a pollutant in the environment
corrective action (EPA, RCRA)
Clean Air Act
consent agreement/final order
Carcinogen Assessment Group (EPA, ORD)
corrective action management unit (EPA, RCRA)
corrective action plan (EPA, RCRA)
capacity assurance plan (EPA, CERCLA)
critical aquifer protection area
categorical exclusion (EPA, NEPA)
Chemical Carcinogenesis Research Information System (NLM, Toxnet)
Centers for Disease Control (HHS, PHS)
Comprehensive Environmental Response, Compensation and Liability Act
CERCLA Information System
Center for Environmental Research Information (EPA-ORD, Cincinnati)
Chemical Evaluation Search and Retrieval System (CIS)
Council on Environmental Quality
conditionally exempt small quantity generator
Chlorofluorocarbon
Code of Federal Regulations
Chemical Identification (includes SUPERLIST) (NLM, ELHILL)
Chemical Dictionary Online (NLM, ELHILL)
Chemical emissions toxicity inventory database (EPA)
Chemical Transportation Emergency Center
Chemical Hazard Response Information System (USCG)
CERCLA hazardous substance
Chemical Inventory List (EPA, EPCRA)
Computer Information System (commercial user network)
Chemical Manufacturers Association
corrective measures implementation (EPA, RCRA)
corrective measures study (EPA, RCRA)
compliance order
carbon monoxide
chemical oxygen demand
Corps of Engineers
conventional pollutant (EPA, CWA)
Acronyms, and- Abbreviations
Vlll
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CP
CPF
CPSC
CQAP
CRA
CRAVE
CRP
CRS
CSF
CTCP
CWA
CZMA
D
D
D—
DAF
DART
DCQAP
DE
DEIS
DERA
DERMAL
DERP
DIRLINE
DMP
DMR
DNFA
DOC
DOD
DOE
DOI
DOJ
DOL
DOR
DOT
DQO
ORE
DW
DWCD
DWHAS
E
EA
EA
EC50
EcA
ECAO
criteria pollutant (EPA, CAA)
cancer (carcinogenic) potency factor
Consumer Product Safety Commission
construction quality assurance plan
classification review area (EPA, SDWA)
carcinogen risk assessment verification endeavor (EPA, ECAO)
community relations plan(ning) (EPA, CERCLA)
Congressional Research Services
cancer slope factor
Clinical Toxicology of Commercial Products (Gleason et at., CIS)
Clean Water Act
Coastal Zone Management Act
disposer, disposal
dose of a pollutant in a receptor (mg/kg/day)
waste ID for characteristic hazardous wastes (EPA, RCRA)
dilution-attenuation factor (EPA, RCRA)
Development and Reproductive Toxicology (NLM, Toxnet)
data collection quality assurance plan
destruction efficiency
draft environmental impact statement
defense environmental restoration account
dermal absorption and toxicity database (CIS)
defense environmental restoration program
Directory of Information Resources Online (NLM)
data management plan
discharge monitoring report (EPA, CWA)
determination of no further action (EPA, RCRA)
U.S. Department of Commerce
U.S. Department of Defense
U.S. Department of Energy
U.S. Department of the Interior
U.S. Department of Justice
U.S. Department of Labor
Determination of Release (EPA, RCRA)
U.S. Department of Transportation
data quality objective (EPA)
destruction removal efficiency
drinking water
Drinking Water Criteria Document (EPA, SDWA)
Drinking Water Health Advisory Summary (EPA, SDWA)
toxicity characteristic hazardous waste code (EPA, RCRA)
environmental assessment (EPA, NEPA)
endangerment assessment
median effective concentration
ecological assessment
Environmental Criteria and Assessment Office (EPA)
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Acronyms and Abbreviations
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ED
ED50
EE/CA
EEGL
EEL
EERU
EF
EFD
EHS
EIA
EIES
EIS
EMIC
EMICBACK
ENU
ENVIROFATE
EO
EP
EP-TOX
EPA
EPCRA
EPTC
ERCS
ERT
ESA
ESD
ETICBACK
ExA
F—
FACA
FCL
FCO
FEIS
FEMA
FEPCA
FFA
FFCA
FFCM
FFSRA
FIFRA
FIT
FLPMA
FOIA
FONSI
FR
FRG
FRL
exposure duration
median effective dose
engineering evaluation/cost analysis
emergency exposure guidance level (NRC)
emergency exposure level (WHO)
Environmental Emergency Response Unit
exposure frequency
exposure frequency and duration
extremely hazardous substance (EPA, EPCRA)
environmental impact assessment (EPA, NEPA)
Electronic Information Exchange System (EPA)
environmental impact statement (study) (EPA, NEPA)
Environmental Mutagen Information Center (NLM, Toxnet)
Environmental Mutagen Information Center Backfile (NLM, Toxnet)
elementary neutralization unit (EPA, RCRA)
bioconcentration and half-life factors database (CIS)
executive order
extraction procedure (EPA, RCRA)
extraction procedure toxicity (EPA, RCRA)
U.S. Environmental Protection Agency
Emergency Planning and Community Right-to-Know Act
extraction procedure toxicity characteristics
Emergency Response Cleanup System
Environmental Response Team
Endangered Species Act (FWS)
explanation of significant differences (EPA, CERCLA)
Environmental Teratology Information Center Backfile (NLM, Toxnet)
exposure assessment
waste ID for nonspecific-source hazardous wastes (EPA, RCRA)
financial assurance for corrective action (EPA, RCRA)
final cleanup level
Federal Coordinating Officer
final environmental impact statement
Federal Emergency Management Agency
Federal Environmental Pesticide Control Act
federal facilities agreement
federal facilities compliance agreement
federal facilities compliance manual
federal facilities site remediation agreement
Federal Insecticide, Fungicide, and Rodenticide Act
Field Investigation Team
Federal Land Policy Management Act
Freedom of Information Act
finding of no significant impact (EPA, NEPA)
Federal Register
final remediation goals
final remediation level (EPA, CERCLA)
Acronyms and Abbreviations
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FRSS
FS
FWPCA
FWS
G
G/Tp
GAC
GACT
GC
GC/MS
GENE-TOX
GIABS
GOCO
GSA
GW
GWA
GWPS
GWQA
H
HA
HAD
HAP
HARM
HASP
HAZINF
HAZWOPER
HC
HC
HCh
HEA
HEA
HEAD
HEAST
HEED
KEEP
HH&E
HHS
HHWE
HI
HM
HMTA
HQ
HRS
HS
HSDB
HSWA
Federal Register Search System
feasibility study (EPA, CERCLA)
Federal Water Pollution Control Act
U.S. Fish and Wildlife Service
generator
generator/transporter
granular activated carbon
generally available control technology
gas chromatograph(y)
gas chromatography/mass spectrometry
genetic toxicology database (NLM, Toxnet)
gastrointestinal absorption database (CIS)
government-owned, contractor-operated facility
Government Services Administration
groundwater
Groundwater Act of 1987
groundwater protection standard (EPA, RCRA)
groundwater quality assessment (EPA, RCRA)
acute hazardous waste code (EPA, RCRA)
hazard (or health) assessment
Health Assessment Document (EPA)
hazardous air pollutant (EPA, CAA)
hazard assessment rating methodology
health and safety plan
Hazardous Chemical Information and Disposal Guide (U. of Alberta)
hazardous waste operations and emergency service
hazardous constituent (EPA, RCRA)
hydrocarbons
hazardous chemical (OSHA)
health effects assessment (EPA)
health and environment assessment (EPA)
Health Effects Assessment Document (EPA)
Health Effects Assessment Summary Tables (EPA)
Health and Environment Effects Document (EPA)
Health and Environmental Effects Profile (EPA)
human health and the environment
U.S. Department of Health and Human Services
human health, welfare and the environment
hazard index
hazardous material (DOT, HMTA)
Hazardous Materials Transportation Act (DOT)
hazard quotient
Hazard Ranking System (EPA, CERCLA)
hazardous substance (EPA, CWA)
Hazardous Substances Data Bank (NLM, Toxnet)
Hazardous and Solid Waste Amendments (EPA, RCRA)
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Acronyms and Abbreviations
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HW
HWMF
HWMU
I
I
IAG
IARC
ICL
IDLH
IFB
IHCS
ILR
IRIS
IRP
IS
I&SE
ISHOW
IUPAC
K—
LAER
LC50
LD50
LDF
LDU
LEPC
LF
LFD
LLRWPA
LOGP
LOIS
LQG
LT
LTU
LUST
MACT
MARPOL
MCL
MCLG
MCS
MEI
MEDLARS
MEP
MF
mg/kg
hazardous waste (EPA, RCRA)
hazardous waste management facility (EPA, RCRA)
hazardous waste management unit (EPA, RCRA)
ignitable hazardous waste code (EPA, RCRA)
intake rate
interagency agreement (EPA, CERCLA)
International Agency for Research on Cancer
initial cleanup level
immediately dangerous to life or health (NIOSH)
Invitation for Bids
imminently hazardous chemical substance (EPA, TSCA)
individual lifetime risk
Integrated Risk Information System (NLM, Toxnet)
installation restoration program
interim status (EPA, RCRA)
imminent and substantial endangerment
Information System for Hazardous Organics in Water (CIS)
International Union of Pure and Applied Chemists
waste ID for specific-source hazardous wastes (EPA, RCRA)
lowest achievable emission rate (EPA, CAA)
median lethal concentration
median lethal dose
land disposal facility (EPA, RCRA)
land disposal unit (EPA, RCRA)
local emergency planning committee (EPA, EPCRA)
landfill
local fire department
Low Level Radioactive Waste Policy Act
bioconcentration factors database
loss of interim status (EPA, RCRA)
large quantity generator
lifetime
land treatment unit
leaking underground storage tank(s)
maximum achievable control technology (EPA, CAA)
Marine Pollution Treaty (USCG)
maximum contaminant level (EPA, SDWA)
maximum contaminant level goal (EPA, SDWA)
media cleanup standard (EPA, RCRA)
maximum exposed individual (EPA, RCRA)
Medial Literature Analysis and Retrieval System (NLM)
maximum extent practicable
modifying factor (EPA)
milligrams per kilogram
Acronyms and Abbreviations
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mg/1
MOA
MOS
MPSRA
MPS
MSDS
MSHA
MTD
MTR
MSW
NAAQS
NAS
NEAR
NCA
NCI
NCP
NEPA
NESHAP(S)
NFPA
NHPA
NIH
NIOSH
NIPDWS
NLM
NOAA
NOAEL
NOD
NOEL
NOI
NONC
NOV
NOx
NPDES
NPL
NRC
NRC
NRC
NRDA
NRT
NSF
NSPS
NTIS
NTP
NWPA
O&G
O&M
milligrams per liter
memorandum of agreement
margin of safety
Marine Protection, Research, and Sanctuaries Act (EPA)
media protection standard (EPA)
material safety data sheet (OSHA)
Mining Safety and Health Administration
maximum tolerated dose (EPA)
minimum technology requirements (EPA, RCRA)
Municipal Solid Waste
National Ambient Air Quality Standard (EPA, CAA)
National Academy of Science
nonbinding allocation of responsibility
Noise Control Act (EPA)
National Cancer Institute (NIH)
National (oil and hazardous substances) Contingency Plan (CERCLA)
National Environmental Policy Act (all federal agencies)
national emission standards for hazardous air pollutants (EPA, CAA)
National Fire Protection Association
National Historic Preservation Act
National Institute of Health
National Institute of Occupational Safety and Health
national interim primary drinking water standards (EPA, SDWA)
National Library of Medicine (HHS, PHS)
National Oceanic and Atmospheric Administration (DOC)
no observed adverse effect level
notice of deficiency (EPA, RCRA)
no observed effect level
notice of intent (to prepare an EIS)
notice of noncompliance
notice of violation
nitrogen oxides
National Pollution Discharge Elimination System (EPA, CWA)
National Priorities List (EPA, CERCLA)
Nuclear Regulatory Commission
National Response Center
National Research Council (NAS)
natural resource damage assessment
National Response Team
National Science Foundation
new source performance standards (EPA, CAA)
National Technical Information Service
National Toxicology Program
Nuclear Waste Policy Act
oil and grease
operation and maintenance
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Acronyms and Abbreviations
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OE
OECM
OERR
OGC
OHM/TADS
OMB
O&MP
0/0
ORD
OSC
OSHA
OSHA
OSM
OSW
OSWER
OTA
OTS
OU
OUST
OWPE
P—
PA
PAAT
PAC
PAH
PCBs
PCDD
PCDF
PCP
PDR
PECMT
PEL
PHRED
PSHA
PHYTOTOX
PI
PIAT
PIC
PIG
PIP
PL
PM
PMN
PMP
PN
PNA
Office of Enforcement (EPA)
Office of Enforcement and Compliance Monitoring (EPA)
Office of Emergency Response and Remediation (EPA, OSWER)
Office of General Counsel (EPA)O
Oil and Hazardous Materials/Technical Assistance Data System (EPA)
Office of Management and Budget
operation and maintenance plan
owner/operator (EPA, RCRA)
Office of Research and Development
On-Scene Coordinator
Occupational Safety and Health Administration (DOL)
Occupational Safety and Health Act
Office of Surface Mining (DOI)
Office of Solid Waste (EPA, OSWER)
Office of Solid Waste and Emergency Response (EPA)
Office of Technology Assessment (Congress)
Office of Toxic Substances (EPA, OPTS)
operable unit (EPA, CERCLA)
Office of Underground Storage Tanks (EPA)
Office of Waste Programs Enforcement (EPA, OSWER)
waste ID for acutely hazardous commercial chemical products (RCRA)
preliminary assessment (EPA, CERCLA)
Public Affair Assistance Team
powdered activated carbon
polycyclic aromatic hydrocarbons
polychlorinated biphenyls
polychlorinated dibenzo-/?-dioxin
polychlorinated dibenzofurans
pentachlorophenol
Physicians' Desk Reference
preliminary evaluation of corrective measures technology
permissible exposure limit (OSHA)
Public Health Risk Evaluation Database (EPA)
Public Service Health Act
Terrestrial plant toxicology database (CIS)
preliminary injunction
Public Information Assistance Team
product(s) of incomplete combustion
program implementation guidance
public involvement plan
public law
project manager
premanufacture notices
program management plan
public notice
polynuclear aromatic (use PAH)
Acronyms and Abbreviations
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PNC
POC
POD
POE
POHC
POM
POTW
PP
PP
ppb
PPE
PPIC
ppm
PPP
ppt
PQL
PR
PRAO
PRO
PRP
PSD
q, q*. qi
QAPP
QA/QC
QRA
QSAR
R
R
RA
RA
RA
RACT
RAn
RAO
RAP
RBC
RC
RCh
RComp
RCRA
RD
RD&D
RE
REL
REMFIT
RFA
public notice and opportunity of comment
point of compliance (EPA)
point of departure (EPA)
point of exposure
principle organic hazardous constituent
polycyclic organic matter
publically owned treatment works (EPA, CWA)
priority pollutant (EPA, CWA)
proposed plan (EPA, CERCLA)
parts per billion
personal protective equipment
Pollution Prevention Information Clearinghouse (EPA)
parts per million
pollution prevention planning (EPA)
parts per trillion
practical quantitation limit
preliminary review (EPA, RCRA)
preliminary remedial action objectives (EPA, CERCLA)
preliminary remediation goal (EPA, CERCLA)
potentially responsible party (EPA, CERCLA)
prevention of significant deterioration (EPA, CAA)
Same as SF and CPF
quality assurance project plan (EPA)
quality assurance/quality control
quantitative risk assessment
Quantitative Structure Activity Relationships (Montana State Univ.)
reactivity hazardous waste code (EPA, RCRA)
acceptable risk level (EPA)
remedial action (EPA, CERCLA)
risk assessment
Regional Administrator
reasonably available control technology (EPA, CAA)
risk analysis
remedial action objective (EPA, CERCLA)
remedial action plan
rotating biological contactor
risk communication
risk characterization
remedy completion
Resource Conservation and Recovery Act
remedial design (EPA, CERCLA)
research, development and demonstration
risk evaluation
recommended exposure limit (NIOSH)
Field Investigation Team for EPA Remedial Action
RCRA facility assessment (EPA, RCRA)
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Acronyms and Abbreviations
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RfC
RfCdt
RfC.
RfD
RfDdt
RfD,
RFI
RFP
RI
RI/FS
RIM
RJ
RM
RME
RMI
RMCL
RN
RO
ROD
RP
RP
RPAR
RPJ
RPM
RQ
RR
RR
RRC
RRS
RRT
RS
RS
RS
RSD
RTECS
RU
RW
RWMU
S
SAB
SARA
SC
SDWA
SERC
SES
SF
SF
(Inhalation) reference concentration (generic or chronic) (EPA)
reference concentration (developmental/teratogenic) (EPA)
reference concentration (subchronic) (EPA)
(Oral) reference dose (generic or chronic) (EPA)
reference dose (developmental/teratogenic) (EPA)
reference dose (subchronic) (EPA)
RCRA facility investigation (EPA, RCRA)
Request for Proposal
remedial investigation (EPA, CERCLA)
remedial investigation/feasibility study
regulatory interpretative memorandum
risk judgment
risk management
reasonable maximum exposure (EPA)
risk management implementation (EPA, RCRA)
recommended maximum contaminant level (same as MCLG)
risk negotiation
reverse osmosis
record of decision (EPA, CERCLA)
risk perception
responsible party (EPA, CERCLA)
rebuttable presumption against registration (EPA, FIFRA)
risk perception and judgment
Regional Project Manager
reportable quantity (EPA, CERCLA)
residual risk
risk reduction
Regional Response Center
risk reduction studies
Regional Response Team
regulated substances (EPA, UST)
remedy selection
risk substitution
risk specific dose (EPA)
Registry of Toxic Effects of Chemical Substances (NLM, Toxnet)
regulated unit (EPA, RCRA)
remediation waste
remediation waste management unit (EPA, RCRA)
storer, storage
Science Advisory Board
Superfund Amendments and Reauthorization Act
specific conductance
Safe Drinking Water Act
State Emergency Response Commission (EPA, EPCRA)
Senior Executive Service
safety factor (EPA)
slope factor (EPA)
Acronyms and Abbreviations
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SHPO
SI
SI
SI
SIC
SIP
SITE
SMCL
SMCRA
SNARL
SNC
SNUR
SOLUB
SPCC
SQG
SSC
SW
SWDA
SWMF
SWMU
T
T
TA
TAG
TAR
TAT
TBC
TC
TCA
TCE
TCh
TC50
TCDD
TCL
TCL
TCLP
TD50
TDS
T&E
TEGD
THM
TIP
TLV
TLV-C
TLV-STEL
TLV-TWA
TMV
State Historic Preservation Officer
sampling inspection (EPA, RCRA)
site inspection (EPA, CERCLA)
surface impoundment
standard industrial classification (cede)
state implementation plan (EPA, CAA)
Superfund Innovative Technology Evaluation Program (EPA-ORD)
secondary maximum contaminant level
Surface Mining Control and Reclamation Act (DOI-OSM)
suggested no adverse reaction level
significant noncomplier (EPA)
significant new use rule (EPA, TSCA)
aqueous solubility database (Univ. of Arizona)
spill prevention, control, and countermeasure (plan) (EPA, CWA)
Small quantity generator
Scientific Support Coordinator
solid waste (EPA, RCRA)
Solid Waste Disposal Act
solid waste management facility (EPA, RCRA)
solid waste management unit (EPA, RCRA)
toxicity hazardous waste code (EPA, RCRA)
treater, treatment
toxicity assessment
technical assistance grant (EPA, CERCLA)
technical amendment to the regulations
Technical Assistance Team
advisory, criteria, or guidance to be considered (EPA, CERCLA)
toxicity characteristic (EPA, RCRA)
trichloroethane
trichloroethylene
toxic chemical (EPA, EPCRA)
median toxic concentration
2,3,7,8-Tetrachlorodibenzo-/?-dioxin
toxic chemical list (EPA, EPCRA)
target cleanup level (EPA, RCRA)
toxicity characteristic leaching procedure (EPA, RCRA)
median toxic dose
total dissolved solids
test and evaluation facility
Technical Enforcement Guidance Document (EPA, RCRA)
trihalomethane
Toxicology Information Program (NLM)
threshold limit value (ACGIH)
TLV-ceiling (ACGIH)
TLV-short-term exposure limit (ACGIH)
TLV-time-weighted average (ACGIH)
toxicity, mobility, and volume
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Acronyms and Abbreviations
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TOC
TOX
TOXLINE
TOXLIT
TOXNET
Tp
TP
TPQ
TRI
TRIFACTS
TRO
TS
TSCA
TSCATS
TSD
TSDF
TSP
TSS
TSS
TU
TUHC
TV
U—
UF
UIC
ur3
use
USCA
USCG
USDW
USGS
UST
VGA
VOC
VSI
W
WHO
WL
WP
WQA
WQC
WQS
WWTU
total organic carbon
total organic halogen
Toxicology Information Online (NLM, ELHILL)
toxicology literature from special sources (NLM, ELHILL)
Toxicology Data Network (NLM, MEDLARS)
transporter
toxic pollutant (EPA, CWA)
threshold planning quantity (EPA, EPCRA)
Toxic Chemical Release Inventory (EPA, EPCRA, NLM, Toxnet)
Toxic Chemical Release Inventory Fact Sheets (NLM, Toxnet)
temporary restraining order
toxic substance (EPA, TSCA)
Toxic Substances Control Act
Toxic Substances Control Act submissions
treatment, storage, or disposal
treatment, storage, or disposal facility
total suspended particulates
total suspended solids
total settleable solids
temporary unit (EPA, RCRA)
total unburned hydrocarbons
toxicity value
waste ID for toxic commercial chemical products
uncertainty factor
Underground Injection Control Program (EPA, SDWA)
use, reuse, recycle, reclaim
United States Code
United States Code Annotated
U.S. Coast Guard
underground source of drinking water (EPA, SDWA)
United States Geological Survey
underground storage tank (EPA, RCRA)
volatile organic analyzer
volatile organic carbon (or compound)
visual site inspection (EPA, RCRA)
weight of receptor
World Health Organization
warning letter
waste pile
Water Quality Act
water quality criterion (EPA, CWA)
water quality standard (EPA, CWA)
wastewater treatment unit (EPA, RCRA)
Acronyms and Abbreviations
xvin
7/95
-------
Section 1
-------
Treatment Technologies
for Superfund
(165.3)
Orientation and Introduction
Student Guide
-------
TREATMENT TECHNOLOGIES
FORSUPERFUND
(165.3)
Presented by:
Halliburton NUS Corporation
EPA Contract No. 68-C2-0121
s-i
Orientation and Introduction
Agenda:
• Environmental Response Training Program (ERTP) overview
• Synopsis of ERTP courses
• Course layout and agenda
• Course materials
Facility information
Treatment Technotogie* for Supeffund 7/95
Oriontsbon &nd Introduction
-------
Notes
Treatment Technologiei ftx Supeifund 7/85
Orientation and Introduction page 3
-------
ERTP OVERVIEW
Comprehensive
Environmental Response, Compensation 1
and Liability Act of 1 980 1
(CERCLA) 1
Super-fund Amendments and Reauthorization Act of 1 986 1
(SARA) 1
U.S. Environmental Protection Agency 1
(EPA) 1
Environmental Response Training Program 1
(ERTP) |
S-2
ERTP Overview
In 1980, the U.S. Congress passed the Comprehensive Environmental Response, Compensation and
Liability Act (CERCLA), also known as Superfund. In 1986, the Superfund Amendments and
Reauthorization Act (SARA) was passed. This act amended CERCLA. CERCLA provides for liability,
compensation, cleanup, and emergency response for hazardous substances released into the environment
and for the cleanup of inactive waste disposal sites. The U.S. Environmental Protection Agency (EPA)
allocated a portion of Superfund money to training. EPA's Environmental Response Team (ERT)
developed the Environmental Response Training Program (ERTP) in response to the training needs of
individuals involved in Superfund activities.
Treatment Technologic* tor Superfund
Orientation and Introduction
7/95
-------
Notes
Treatment Tochnotogias for Superfund 7/05
Orientation and Introduction paoe 5
-------
ERTP OVERVIEW
U.S. Environmental Protection Agency 1
(EPA) 1
Office of Solid Waste and Emergency Response 1
(OSWER) |
Environmental Response Team 1
(ERT) 1
Environmental Response Training Program 1
(ERTP) 1
S-3
ERTP Overview
ERTP is administered by ERT, which is part of OSWER. ERT offices and training facilities are located in
Cincinnati, Ohio, and Edison, New Jersey. ERT has contracted the development of ERTP courses to
Halliburton NUS Corporation (EPA Contract No. 68-C2-0121). The ERTP program provides education
and training for environmental employees at the federal, state, and local levels in all regions of the United
States. Training courses cover areas such as basic health and safety and more specialized topics such as
air sampling and treatment technologies.
Treatment Technologies for Supartund
Orientation and Introduction
7/95
pages
-------
Notes
Treatment Technotogiet for Superfund 7/05
Orientation and Introduction
-------
Types of Credit Available
Continuing Education Units
(2.25 CEUs)
CEU Requirements
100% attendance at this course.
>70% on the exam.
Treatment Technologies for Superfund
Orientation and Introduction
7/85
pages
-------
Notes
Treatment Technologies for Supertund 7/95
Orientation and Introduction
-------
ERTP Courses
Health and Safety Courses
Hazardous Materials Incident Response Operations (165.5)
• Safety and Health Decision-Making for Managers (165.8)
• Emergency Response to Hazardous Material Incidents (165.15)
Technical Courses
• Treatment Technologies for Superfund (165.3)
• A ir Monitoring for Hazardous Materials (165.4)
• Risk Assessment Guidance for Superfund (165.6)
• Introduction to Groundwater Investigations (165.7)
• Sampling for Hazardous Materials (165.9)
Radiation Safety at Superfund Sites (165.11)
Special Courses
Health and Safety Plan Workshop (165.12)
• Design of Air Impact Assessments at Hazardous Waste Sites (165.16)
• Removal Cost Management System (165.17)
Inland Oil Spills (165.18)
Courses Offered in Conjunction with Other EPA Offices
v' Chemical Emergency Preparedness and Prevention Office (CEPPO)
• Chemical Safety Audits (165. 19)
Site Assessment Branch
Preliminary Assessment
Site Investigation
Federal Facilities Preliminary Assessment/Site Investigation
Hazard Ranking System
Hazard Ranking System Documentation Record
Treatment Technologies tor Superfund
Orientation and Introduction
7/85
P*0* 10
-------
Notes
Treatment Technologies for Superfund 7/95
Orientation and Introduction P&9* 11
-------
Course Goals
Identify treatability study screening resources.
Identify the processes and explain the limitations of the most
frequently used treatment technologies.
Explain the principles and applications of biological technology.
Describe three types of incinerator design.
Identify references that describe emerging treatment technologies.
Treatment T«chnotogie« tor Supertund
Onentabon and Introduction
7/95
page 12
-------
Notes
Treatment Technologist taf Superfund 7/05
Orientation and Introduction page 13
-------
Course Layout and Agenda
Key Points:
Agenda times are only approximate. Every effort is made to complete units, and to
finish the day, at the specified time.
Classes begin promptly at 8:15 am on Tuesday and 8:00 am Wednesday through
Friday. Please arrive on time to minimize distractions to fellow students.
Breaks are given between units.
Lunch is 1 hour.
Each student must take the examination.
Direct participation in field or lab exercises is optional. Roles are randomly assigned
to ensure fairness.
Attendance at each lecture and exercise is required in order to receive a certificate.
Treatment Technologies for Supertund 7/95
Orientation and Introduction page 14
-------
Notes
Treatment Technologies tor Superfund 7/95
Orientation and Introduction page 15
-------
Training Evaluation
The Training Evaluation is a tool to collect valuable feedback from YOU
about this course.
We value YOUR comments!! Important modifications have been made to
this course based on comments of previous students.
DO
Write in your comments at the end of
each unit!
Tell us if you feel the content of the
course manual (and workbook) is clear
and complete!
Tell us if you feel the activities and
exercises were useful and helpful!
Tell us if you feel the course will help
you perform related duties back on the
job!
Complete the first page at the end of
the course before you leave!
Write comments in ink.
DON'T
Hold back!
Focus exclusively on the presentation
skills of the instructors.
Write your name on the evaluation, if
it will inhibit you from being direct
and honest.
Treatment Technologist for Superfund
Orientation and Introduction
7195
page 18
-------
Notes
Treatment Technologies for Superfund 7/85
Orientation and Introduction P>9> 17
-------
Facility Information
O1
Please put beepers in the vibrate mode and
turn off radios. Be courteous to fellow
students and minimize distractions.
Emergency
Telephone
Numbers
Emergency Exits
Alarms
Sirens
Treatment T»chnotog>«t tor Suporfund
Orientation and Introduction
7/95
-------
Notes
Treatment Technotogiet for Supeftund 7/95
Orientation and Introduction p,^ 19
-------
Section 2
-------
SUPERFUND AND THE NATIONAL
CONTINGENCY PLAN
Li
* \
STUDENT PERFORMANCE OBJECTIVES
At the conclusion of this unit, students will be able to:
1. Describe the purpose of Comprehensive Environmental
Response, Compensation and Liability Act (CERCLA)
2. List three objectives of CERCLA
3. Describe three changes to CERCLA resulting from the
Superfund Amendments and Reauthorization Act (SARA)
4. List five of the nine criteria used to evaluate feasibility
studies
5. Describe the purpose of the National Contingency Plan
6. List four phases of the National Contingency Plan
7. List three steps in the Superfund Accelerated Cleanup Model
(SACM)
8. Describe the objective of presumptive remedies
9. List a type of waste site for which a presumptive remedy is
being developed.
NOTE: Unless otherwise stated, the conditions for
performance are using all references and materials
provided in the course, and the standards of
performance are without error.
7/95
-------
NOTES
T'
T
SUPERFUNDANDTHE
NATIONAL
CONTINGENCY PLAN
S-1
CERCLA
(Superfund)
• Comprehensive Environmental Response,
Compensation and Liability Act
• Enacted in 1980
• Designed to respond to uncontrolled waste
sites
• Reauthorized by the Superfund
Amendments and Reauthorization Act
(tSARAbof 1986
CERCLA (cont.)
(Superfund)
Sets priorities for waste sites /
Makes responsible parties pay
V
• Creates a Hazardous Waste Trust Fund(>
• Advances technical capabilities
S-3
I/-J
l>
*A/*V
7/95
Superfund and the National Contingency Plan
-------
NOTES
SARA
• Removal actions
••• Enforcement authority
• Citizen and state involvement
• Research, development, and training
S-4
RI/FS
Remedial investigations (Rl) - data
gathering
Feasibility studies (FS) - remedy analysis
-• Selection criteria
Superfund Accelerated Cleanup Model
(SACM)
Presumptive remedies
s-s
CRITERIA FOR TECHNOLOGY
SELECTION
•rOverall protection of human health and
N environment
with requirements (ARARs)
'fLong-term effectiveness and permanence
Reduction of toxicity, mobility, and/or
volume
s-e
Superfund and the National Contingency Plan
7/95
-------
CRITERIA (cont.)
5 • Short-term effectiveness
Implementability
Cost
State acceptance
Community acceptance
CRITERIA (cont.)
Record of decision (ROD)
Threshold criteria
Balancing criteria
Modifying criteria
8-7
S-8
NATIONAL CONTINGENCY PLAN
• Clean Water Act/CERCLA/SARA
• Emergency responses (On-Scene
Coordinators)
• Remedial cleanups (Remedial Project
Managers) RPf/1
• Remedial action evaluation
s-e
NOTES
7/95
Superfund and the National Contingency Plan
-------
NOTES
U
REMEDIAL ACTION PROCESS
Site discovery
Preliminary assessment/site investigation
/SI)
Hazard Ranking System (MRS)
National Priority List (NPL)
S-10
REMEDIAL ACTION PROCESS
(cont.)
• RI/FS
• ROD
• Remedial design (RD)
• Remedial action (RA)
Delisting
S-11
Site screening and assessment
Early action i2>
-------
NOTES
PRESUMPTIVE REMEDIES
Preferred technologies
Volatile organic compounds in soil
Wood treating sites
S-13
7/95
Superfund and the National Contingency Plan
-------
REFERENCES
National Oil and Hazardous Substances Pollution Contingency Plan. Final Rule, 40 CFR part 300
(The National Contingency Plan).
Superfund: Looking Back, Looking Ahead. EPA Journal Special Section, Section 1
CERCLA/SARA Part 1.
U.S. EPA. 1993. Presumptive Remedies: Policy and Procedures. EPA/540/F-93-047. U.S.
Environmental Protection Agency, Washington, DC.
U.S. EPA. 1993. Superfund Accelerated Cleanup Model (SACM), Superfund: What It Is, How
It Works. Presentation by the U.S. Environmental Protection Agency, National Technology
Seminar, Albuquerque, NM.
Superftind and the National Contingency Plan 6 7/95
-------
Section 3
-------
PHYSICAL AND CHEMICAL
CHARACTERISTICS
STUDENT PERFORMANCE OBJECTIVES
At the conclusion of this unit, students will be able to:
1. Define the following terms: soil, soil formation, soil
texture, porosity, secondary porosity, hydrologic cycle,
permeability, aquifer, and aquitard
2. Define the following terms: molecular weight, specific
gravity, solubility, vapor pressure, Henry's Law Constant,
organic carbon partition coefficient (K^), octanol/water
partition coefficient (K^), and biodegradability
3. List at least one treatment technology affected by the
following: molecular weight, specific gravity, solubility,
vapor pressure, Henry's Law Constant, K«> K^, and
biodegradability.
NOTE: Unless otherwise stated, the conditions for
performance are using all references and materials
provided in the course, and the standards of
performance are without error.
7/95
-------
NOTES
PHYSICAL AND
CHEMICAL
CHARACTERISTICS
8-1
SOIL
• Material that supports the growth of plants
• Contains:
- Organic matter
- Rock and mineral fragments
- Water
- Air
SOIL FORMATION
Criteria
• Parent rock or sediment
• Climate
• Topography
• Presence and abundance of organisms
• Time
8-3
7/95
Physical and Chemical Characteristics
-------
NOTES
GRAIN SIZES
Boulder/
cobble
>76 mm
Bowling ball/
grapefruit
Gravel 4.76-76 mm Orange/
pea
8-4
GRAIN SIZES (cont.)
Sand 0.074-4.76 mm Rocksalt/
sugar
Fines <0.074 mm Silt/
clay
8-5
SOIL TEXTURE
• Loam: uniform mixture of sand and silt/clay
that is stable when moist
• Sand, silt, and clay are also soil textures
Physical and Chemical Characteristics
7/95
-------
NOTES
POROSITY
• Ratio of open space within a rock to its
total volume
• Ability to hold or store water
• Depends on the size and number of pores
• Generally high in sedimentary rocks
• Low in crystalline igneous and
metamorphic rocks
8-7
Void space
Percent
porosity
Sand grain
Total Volume - Volume Soil Particles
Total Volume
X 100
SECONDARY POROSITY
S-B
7/95
Physical and Chemical Characteristics
-------
NOTES
HYDROLOGIC
CYCLE
Transpiration T
Precipitation
vapo ration
//////
Soil moisture/V//
Pore spaces partially \
t
Unsaturated
(vadose)
zone
PERMEABILITY
The ease with which water will
move through a porous medium
S-12
Physical and Chemical Characteristics
7/95
-------
NOTES
AC
JUIFERS AND AQUITA
' ^^ ^^ ^^ ^C ^C ^C ^Cx^^C xC
Unconfined aquifer
1 ' Aqurtard i;
w v^X^C** „ >?1
= Water 7 -= L
E table |
,- x-.^....-'fH |
,r.J: ..i.1 ' . i
Confined aquifer = |
~r- .,, Aquitard"' '^:~L^J- ',.r ,|
t
Confined aquifer F
RDS^
— p-».
.5
z
j:
•••
mm
mm
W1
•^
8-13
FATE OF CONTAMINANTS?
Do they...
• Float
• Dissolve
• Sink
• Adhere
8-14
FATE OF CONTAMINANTS
(cont.)
How much...
• Is adsorbed
• Is adsorbed
• Volatilizes?
• Is eaten by
to clay?
IN SOIL
to organic matter?
microbes?,-^
• Enters the water table?
\jL
lAkK
8-15
7/95
Physical and Chemical Characteristics
-------
NOTES
WASTE CHARACTERISTICS
Molecular weight, g/mol
Specific gravity, ratio
Solubility (water), mg/L
Vapor pressure, mmHg
8-18
WASTE CHARACTERISTICS (cont.)
Henry's Law Constant, atm-m3/mol
Organic carbon partition coefficient (KoC)
Octanol-water partition coefficient
Biodegradability, subjective
8-17
MOLECULAR WEIGHT
• The sum of the atomic weights of all the
atoms in a molecule
Affects mobility
8-1 a
Physical and Chemical Characteristics
7/95
-------
NOTES
SPECIFIC GRAVITY
The weight of a given volume of substance
compared to the weight of water at 4°C
Can be used to predict whether
compounds are likely to float or sink
1
8-18
SPECIFIC GRAVITY
Examples
Compound
Phenol
PCBs
TCE
Chrysene
Vinyl chloride
Specific Gravity
1.07
1.4-1.5
1.46
1.274
0.912
8-20
SOLUBILITY
The maximum concentration of a chemical
that dissolves in pure water at a given
temperature
Factors that influence solubility:
- Polarity
- Temperature
- pH
8-21
7/95
Physical and Chemical Characteristics
-------
NOTES
VAPOR PRESSURE
The pressure exerted at a given
temperature when a solid or liquid is in
equilibrium with its own vapor
Inversely proportional to boiling point
Directly proportional to temperature
S-22
VAPOR PRESSURE OF WATER
Variation with Temperature
5
10
20
50
100
mmHg
6.54
9.21
17.5
92.5
760
S-23
HENRY'S LAW CONSTANT
Expression that relates the concentration of
a chemical dissolved in the aqueous
phase to the concentration of the chemical
in the gaseous phase when the two are in
equilibrium
VP/S
VP = Vapor pressure, atm
S = Solubility, mol/m3
S-24
Physical and Chemical Characteristics
7/95
-------
NOTES
ORGANIC CARBON PARTITION
COEFFICIENT
Indicates the tendency of a chemical to be
adsorbed by activated carbon
Ranges from 1 to 10,000,000
(the higher the value, the greater the
adsorption)
8-25
ORGANIC CARBON PARTITION
COEFFICIENT (KJ (cont.)
influenced by:
• Temperature
• Grease and oils
• Solids
8-26
ORGANIC CARBON PARTITION
COEFFICIENT (KJ (cont.)
mg compound adsorbed / kg organic carbon
mg dissolved / liter solution
8-27
7/95
Physical and Chemical Characteristics
-------
NOTES
r
Koc VALUES
Chemical Name
PCBs
DCM
Benzene
Tetrachloroethylene
Vinyl chloride
Benzo(b)pyrene
KOSL
53,000
9
83
364
57
550,000
8-28
OCTANOL/WATER PARTITION
COEFFICIENT (K^)
Relates the partitioning of a specific
compound between nonpolar and polar
phases
[X] OCTANOL
[X] WATER
8-2*
K™ VALUES
Chemical Name
PCBs
DCM
Benzene
Tetrachloroethylene
Vinyl Chloride
Benzo(b)pyrene
KOW
6.04
1.30
2.13
2.60
1.38
6.06
8-30
Physical and Chemical Characteristics
10
7/95
-------
NOTES
BIODEGRADABILITY
The susceptibility of a substance to
decompose by microorganisms
Subjective
- Degradable
- Nondegradable
- Refractory
8-ai
7/95
11
Physical and Chemical Characteristics
-------
REFERENCES
U.S. EPA. 1992. Engineering Bulletin: Technology Preselection Data Requirements. EPA/540/5-
92/009. U.S. Environmental Protection Agency, Office of Research and Development, Risk
Reduction Engineering Laboratory, Cincinnati, OH.
Physical and Chemical Characteristics 12 7/95
-------
&EPA
United States
Environmental Protection
Agency
Office of Emergency and
Remedial Response
Washington, DC 20460
.
Research and Development
Cincinnati, OH 45268
;:Superiund
EPA/540/S-92/009
October 1992
Engineering Bulletin
Technology Preselection
Data Requirements
Purpose
Section 121(b) of the Comprehensive Environmental Re-
sponse, Compensation, and Liability Act (CERCLA) mandates
the Environmental Protection Agency (EPA) to select remedies
that 'utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the maxi-
mum extent practicable' and to prefer remedial actions in
which treatment 'permanently and significantly reduces the
volume, toxicity, or mobility of hazardous substances, pollut-
ants, and contaminants as a principal element' The Engineer-
ing Bulletins are a series of documents that summarize the latest
information available on selected treatment and site remedia-
tion technologies and related issues. The summaries and refer-
ences are designed to help remedial project managers, on-
scene coordinators, contractors, and other site deanup managers
understand and select technologies that may have potential
applicability to their Superfund or other hazardous waste sites.
This bulletin provides a listing of soil, water, and contami-
nant data elements needed to evaluate the potential applicabil-
ity of technologies for treating contaminated soils and water.
With this base set of data in hand, experts familiar with the
applicability of treatment technologies can better focus the
advice and assistance they give to those involved at Superfund
sites. The data compiled should permit preselection of appli-
cable treatment methods and the direct elimination of others.
This bulletin emphasizes the site physical and chemical soil
and water characteristics for which observations and measure-
ments should be compiled. However, several other kinds of
information may be equally helpful in assessing the potential
success of a treatment technology including the activity history
of the site, how and where wastes were disposed, topographic
and hydrologk detail, and site stratigraphy. Gathering and
analyzing the information called for in this bulletin prior to
extensive field investigations [i.e., the Remedial Investigation
and Feasibility Study (RI/FS)] will facilitate streamlining and
targeting of the sampling and analytical objectives of the over-
all program.
Additional information on site data requirements for the
selection of specific treatment technologies may be found in
several EPA publications [1] [2] [3] [4] [5].* These documents
form much of the basis for this Engineering Bulletin. The
bulletin may be updated by periodically-issued addenda.
Abstract
A base set of soil and water analytical (measured) data
requirements has been developed to enable prescreening of
technologies that may have potential applicability at Superfund
sites. Data requirements for soils include the traditional engi-
neering properties of soils and data on soil chemistry, including
contaminants and oxygen demand. Analytical data require-
ments for water (usually groundwater) include chemistry, oxy-
gen demand, and pH. Of particular importance in chemical
characterization of both soils and water are contaminating
metals and organic chemicals, whose presence or absence is
often suggested by historical site activities. Sampling and mea-
surements at this stage need not be in great detail, but should
be sufficient to preliminarily characterize the site variability in
three dimensions. Topography, groundwater flow, stratigra-
phy of the contaminated zone, and degree of consolidation will
also affect the choice of treatment technology.
The relationships between each of the data requirements
and specific treatment technologies are briefly summarized.
The detailed reasoning may be found in one or more of the
references.
The guidance presented in this bulletin is not exhaustive.
The data elements are those that have wide technological
applicability and those that can be collected in a straightfor-
ward manner. Data gaps are still likely to exist However, an
almost certain result is that the additional data needs will be
better focused.
Background Information
The background information collected during the Site
Screening Investigation and Preliminary Assessment identifies
the probable types and locations of contaminants present
Study of the chemicals used or stored at the site and the
disposal methods used during the period(s) of operation is
essential. When chemical-use records are unavailable for an
industrial site, knowledge of the Standard Industrial Classification
may indicate the probability of the presence of metals, inorganic,
pesticides, dioxins/furans, or other organics. Information on
what classes and concentrations of chemicals contaminate the
site, where they are distributed, and in what media they appear
is essential in beginning the preselection of treatment
technologies [2, p. 7].
* [reference number, page number]
-------
The contaminant distribution, types, and concentrations
will affect the choice of treatment technology. Other consider-
ations in the selection of treatment options include the proxim-
ity of residential areas and the location of buildings and other
structures. These aspects should be determined early in the
investigation process. Much of the determination of the range
and diversity of contamination, as well as likely contaminant
sources, may be observational, rather than measurement-based.
Basic Measurement Data Requirements
The discussion of data requirements is divided into two
sections, soil and water. For each of the two media, the vertical
and horizontal contaminant profiles should be defined as much
as possible. Information on the overall range and diversity of
contamination across the site is critical to treatment technology
selection. This generally means that samples will be taken and
their physical and chemical characteristics determined. The
following subsections present the characteristics and rationale
for collection of preselection data for each of the two media.
Other documents present similar data requirements, especially
for soils [6].
The minimum set of soil measurement data elements usu-
ally necessary for soil treatment technology preselection is pre-
sented in Table 1. Table 2 presents the basic set of data
necessary for contaminated water treatment technology
preselection. It is common for the two media at one site to be
contaminated with the same substances, thus many of the
required data elements are similar. The information contained
in Table 1 and Table 2 is based on professional judgement.
The ratings in Table 1 and Table 2 are related to measured
values of the parameters. The values are described as "higher"
and "lower" in defining their tendency toward preselecting a
technology group. In general, these descriptors are related to
the tendency of the parameter to enhance or to inhibit particu-
lar processes. Where no symbol is shown for a characteristic in
Table 1 and Table 2, the affect on the associated technology is
considered inconsequential.
Each characteristic is judged, or rated, as to its effect in
preselecting each of the treatment technology groups which
represent various treatment processes. A rating applies gener-
ally to a technology, but it does not ensure that the rating will
be applicable to each specific technology within a technology
group. Examples of specific treatments within the technology
groups are as follows:
• Physical
Soil washing
Soil flushing
Steam extraction
Air stripping
Solvent extraction
• Chemical
Oxidation
Hydrolysis
Polymerization
Vapor extraction
Carbon adsorption
Filtration
Gravity separation
Reduction
Precipitation
• Thermal
Incineration
Plasma Arc
• Biological
Aerobic
Slurry reactor
• Solidification/Stabilization
Cement-based
Fly ash/lime
Kiln dust
Pyrolysis
Thermal desorption
Anaerobic
Land treatment
Vitrification
Asphalt
Soil
Site soil conditions are frequently process-limiting. Pro-
cess-limiting characteristics such as pH or moisture content [6]
may sometimes be adjusted. In other cases, a treatment tech-
nology may be eliminated based upon the soil classification
(e.g., particle-size distribution) or other soil characteristics.
Soils are inherently variable in their physical and chemical
characteristics. Frequently the variability is much greater verti-
cally than horizontally, resulting from the variability in the
sedimentation processes that originally formed the soils. The
soil variability, in turn, will result in variability in the distribution
of water and contaminants and in the ease with which they can
be transported within, and removed from, the soil at a particu-
lar site.
Many data elements are relatively easy to obtain, and in
some cases, more than one test method exists [6] [7] [8] [9]
[10] [11] [12]. Field procedures, usually visual inspection and/
or operation of simple hand-held devices (e.g., auger), are
performed by trained geologists or soils engineers to determine
the classification, moisture content, and permeability of soils
across a site. Due to the fact that zones of gross contamination
may be directly observed, field reports describing soil variability
may lessen the need for large numbers of samples and mea-
surements in describing site characteristics. Common field
information-gathering often includes descriptions of natural soil
exposures, weathering that may have taken place, trench cross-
sections, and subsurface cores. Such an effort can sometimes
identify probable areas of past disposal through observation of
soil type differences, subsidence, overfill, etc.
While field investigations are important, they cannot elimi-
nate the need for or lessen the importance of soil sampling and
measurements sufficient to define those characteristics that are
essential to the selection and design of soil treatment technolo-
gies.
Soil particle-size distribution is an important factor in
many soil treatment technologies. In general, sands and fine
gravels are easiest to deal with. Soil washing may not be
effective where the soil is composed of large percentages of silt
and clay because of the difficulty of separating fine particles
from each other and from wash fluids [13, p. 1]. Fine particles
also can result in high particulate loading in flue gases due to
Engineering Bulletin: Technology Preselection Data Requirements
-------
TABLE 1. SOIL CHARACTERISTICS THAT ASSIST IN
TREATMENT TECHNOLOGY PRESELECTION
TABLE 2. WATER CHARACTERISTICS THAT ASSIST IN TREATMENT
TECHNOLOGY PRESELECTION
OMMCTfROTIC
Particle size
Bulk density
Particle density
Permeability
Moisture content
pHandEh
, Humic content
' Total organic carbon (TOC)
Biochemical oxygen demand (BOD)
Chemical oxygen demand (COD)
Oil and grease
Organic Contaminants
Halogenated volatfles
Halogenated semivolatiles
Nonhalogenated volatile!
Nonhalogenated semivolatiles
PCBs
Pesticides
Dioxins/Furans
Organic cyanides
Organic corrosives
Light Nonaqueous-Phase Liquid
Dense Nonaqueous-Phase Liquid
Heating value (Btu content)
Inorganic Contaminants
Volatile metals
Nonvolatile metals
Asbestos
Radioactive materials
Inorganic cyanides
Inorganic corrosives
Reactive Contaminants
Oxidizers
Reducers
TREATMENT TECHNOIOG 1 CROUP
1
V
•
•
T
O
T
T
T
T
V
T
V
T
T
T
T
T
•
V
1
T
O
T
•
D
V
V
T
T
T
V
T
V
V
V
V
V
T
V
T
V
3
§
•
•
T
O
•
•
•
a
a
T
V
V
T
T
T
T
T
T
0
O
1
•
0
T
T
•
a
o
a
a
T
O
S
0
o
T
a
o
a
o
a
a
a
a
a
a
a
a
m
m
T
T
T
• = higher values support preselection of technology group.
O = lower values support preselection of technology group.
V = Effect is variable among options within a technology
group.
Where no symbol is shown, the effect of that characteristic is
considered inconsequential
CNAMCTERU7K
pH, Eh
Total organic carbon (TOC)
Biochemical oxygen demand (BOD)
Chemical oxygen demand (COD)
Oil and grease
Suspended solids
Nitrogen 6 phosphorus
Organic Contaminants
Halogenated volatfles
Halogenated semivolatiles
Nonhalogenated volatiles
Nonhalogenated semivolatiles
PCBs
Pesticides
Dioxins/Furans
Organic cyanides
Organic corrosives
Light Nonaqueous-Phase Liquid
Dense Nonaqueous-Phase Liquid
Inorganic Contaminants
Asbestos
Radioactive materials
Metals (Drinking Water Stds.)
TREATMENT TZCMMOlOGr CROUP
i
T
T
V
T
T
T
V
T
T
T
T
V
V
T
T
1
T
V
•
Q
T
T
V
T
T
V
T
T
T
T
T
"
I
T
•
•
•
T
T
a
D
T
T
T
T
Q
T
T
T
T
a
Q
i
T
•
Q
•
T
D
Q
Q
• = higher values support preselection of technology group.
O = lower values support preselection of technology group.
V = Effect is variable among options within a technology group.
Where no symbol isshown.theeffectofthat characteristic is considered
inconsequential
turbulence in rotary kilns. Heterogeneities in soil and waste
composition may produce non-uniform feed streams for incin-
eration that result in inconsistent removal rates [1][14]. Fine
particles may delay setting and curing times and can surround
larger particles causing weakened bonds in solidification/stabili-
zation processes, days may cause poor performance of the
thermal desorption technology due to caking [15, p. 2]. High
silt and clay content can cause soil malleability and low perme-
ability during steam extraction, thus lowering the efficiency of
the process [16, p. 2]. Bioremediation processes, such as in
slurry reactors, are generally facilitated by finer particles that
Engineering Bulletin: Technology Preselection Data Requirements
-------
increase the contact area between the waste and microorgan-
isms [14] [17, p. 1].
In situ technologies dependent on the subsurface flowability
of fluids, such as soil flushing, steam extraction, vacuum extrac-
tion, and in situ biodegradation, will be negatively influenced
by the impeding effects of clay layers [15, p. 2] [18, p. 4].
Undesirable channeling may be created in alternating layers of
clay and sand, resulting in inconsistent treatment [2, p. 79].
Larger particles, such as coarse gravel or cobbles, are undesir-
able for vitrification and chemical extraction processes and also
may not be suitable for the stabilization/solidification technol-
ogy [2, p. 93].
The bulk density of soil is the weight of the soil per unit
volume including water and voids, tt is used in converting
weight to volume in materials handling calculations [19, p. 3-
3]. Soil bulk density and particle size distribution are interre-
lated in determining if proper mixing and heat transfer will
occur in fluidized bed reactors [2, p. 39].
Particle density is the specific gravity of a soil particle.
Differences in particle density are important in heavy mineral/
metal separation processes (heavy media separation). Particle
density is also important in soil washing and in determining the
settling velocity of suspended soil particles in flocculation and
sedimentation processes [13, p. 1].
Soil permeability b one of the controlling factors in the
effectiveness of in situ treatment technologies. The ability of
soil-flushing fluids (eg., water, steam, solvents, etc) to contact
and remove contaminants can be reduced by low soil perme-
ability or by variations in the permeability of different soil layers
[16, p. 2] [19, p. 4-9]. Low permeability also hinders the
movement of air and vapors through the soil matrix, lessening
the volatilization of VOCs in vapor extraction [17, p. 2]. Simi-
larly, nutrient solutions, used to accelerate in situ bioremediation,
may not be able to penetrate low-permeability soils in a reason-
able time [1]. Low permeability may also limit the effectiveness
of in-situ vitrification by slowing vapor releases [2, p. 59].
Soil moisture may hinder the movement of air through
the soil in vacuum extraction systems [3, p. 90] [17, p. 1 ]. High
soB moisture may cause excavation and material, transport
problems [20, p. 2] and may negatively impact material feed in
many processes [2] [15, p. 2] [19, p. 4] [21]. Moisture affects
the application of vitrification and other thermal treatments by
increasing energy requirements, thereby increasing costs. On
the other hand, increased soil moisture favors in situ biological
treatment [22, p. 40].
Many treatment technologies are affected by the pH of the
waste being treated. For example, low pH can interfere with
chemical oxidation and reduction processes. The solubility and
speciation of inorganic contaminants are affected by pH. Ion
exchange and flocculation processes, applied after various liq-
uid extraction processes, may be negatively influenced by pH
[1, p. 5,16]. Mtcrobial diversity and activity in bioremediation
processes can be reduced by extreme pH ranges. High pH in
soil normally improves the feasibility of applying chemical ex-
traction and alkaline dehalogenation processes [2, p. 67].
Eh is the oxidation-reduction (redox) potential of the ma-
terial being considered. For oxidation to occur in soil systems,
the Eh of the solid phase must be greater than that of the
organic chemical contaminant [22, p. 19]. Maintaining anaero-
biosis, and thus a low Eh, in the liquid phase, enhances decom-
position of certain halogenated organic compounds [23].
Humic content (humus) is the decomposing part of the
naturally occurring organic content of the soil. The effects of
high humic content upon treatment technologies are usually
negative. It can inhibit soil-vapor extraction, steam extraction,
soil washing, and soil flushing due to strong adsorption of the
contaminant by the organic material [2, p. 76] [17, p. 2].
Reaction times for chemical dehalogenation processes can be
increased by the presence of large amounts of humic materials.
High organic content may also exert an excessive oxygen
demand, adversely affecting bioremediation and chemical oxi-
dation [24, p. 2] [25, p. 1].
Total organic carbon (TOQ provides an indication of the
total organic material present It is often used as an indicator
(but not a measure) of the amount of waste available for
biodegradation [2, p. 109]. TOC includes the carbon both
from naturally-occurring organic material and organic chemical
contaminants. Ordinarily, not all of the organic carbon is
contaminating, but all of it may compete in redox reactions,
leading to the need for larger amounts of chemical reduction/
oxidation reagents than would be required by the organic
chemical contaminants alone [2, p. 97].
Biochemical oxygen demand (BOO) provides an esti-
mate of the biological treatability of the soil contaminants by
measuring the oxygen consumption of the organic material
which is readily biodegraded [3, p. 89]. Chemical oxygen
demand (COO) is a measure of the oxygen equivalent of
organic content in a sample that can be oxidized by a strong
chemical oxkdanL Sometimes COD and BOD can be corre-
lated, and COD can give another indication of biological
treatability or treatability by chemical oxidation [2, p. 97].
COD is also useful in assessing the applicability of wet air
oxidation [2, p. 51].
Oil and grease, when present in a soil, will coat the soil
particles. The coating tends to weaken the bond between soil
and cement in cement-based solidification [14]. Similarly, oil
and grease can also interfere with reactant-to-waste contact in
chemical reduction/oxidation reactions thus reducing the effi-
ciency of those reactions [2, p. 97].
Identification of the site organic and inorganic contami-
nants is the most important information necessary for technol-
ogy prescreening. At this stage, it may not be necessary to
identify specific contaminants, but the presence or absence of
the groups shown in Table 1 should be known. These groups
have been presented in the other Engineering Bulletins in order
to describe the effectiveness of the particular treatment tech-
nology under consideration.
The soil may be contaminated with organic chemicals that
Engineering Bulletin: Technology Preselection Data Requirements
-------
are not miscibte with water. Often, they will be lighter than
water and float on top of the water table. These are called light
nonaqueous-phase liquids (LNAPLs). Those heavier than water
are called dense nonaqueous-phase liquids (DNAPLs). Most of
these liquids can be physically separated from water within the
soil, especially if they are not adsorbed to soil particles.
Volatile, semivolatile, and other organics may be adsorbed
in the soil matrix. Volatiles may be in the form of vapors in the
pores of non-saturated soil, and may be amenable to soil-vapor
extraction. Fuel value, or Btu content, of the contaminated soil
is directly related to the organic chemical content High Btu
content favors thermal treatment, or perhaps recovery for fuel
use.
High halogen concentrations, as in chlorinated organics,
lead to the formation of corrosive acids in incineration systems.
Volatile metals produce emissions that are difficult to remove,
and nonvolatile metals remain in the ash [14].
Metals may be found sometimes in the elemental form,
but more often they are found as salts mixed in the soil.
Radioactive materials are not ordinarily found at waste disposal
sites. However, where they are found, treatment options are
probably limited to volume reduction, and permanent contain-
ment is required. Asbestos fibers require special care to prevent
their escape during handling and disposal; permanent contain-
ment must be provided. Radioactive materials and asbestos
require special handling techniques to maintain worker safety.
Often, specific technologies may be ruled out, or the list of
potential technologies may be immediately narrowed, on the
basis of the presence or absence of one or more of the chemical
groups. The relative amounts of each may tend to favor certain
technologies. For example, significant amounts of dioxin/
furans, regardless of the concentrations of other organics, will
ordinarily lead to preselection of thermal treatment as an alter-
native.
Data available from the preliminary assessment, the site
inspection and the National Priorities List (NPL) activities may
provide most of the contaminant information needed at the
technology prescreening stage. If the data are not sufficient,
waste samples may be scanned for selected priority pollutants
or contaminants from the CERCLA Hazardous Substances List
During the ensuing RI/FS scoping phase, these data are evalu-
ated to identify additional data which must be gathered during
the site characterization. Guidance is available on the RI/FS
process and on field methods, sampling procedures, and data
quality objectives [4][5][6][12] and therefore is not discussed in
this bulletin.
Water
It is common for groundwater and surface water drainage
to be contaminated with the same substances found in soils
derived from previous activities. At Superfund sites, many of
the required data elements are similar, e.g., pH, TOC, BOD,
COD, oil and grease, and contaminant identification and quan-
tification. Frequently, many of the water data elements will be
available from existing analytical data. Some initial data re-
quirements may even be precluded by the collection of exist-
ing regional or local information on surface and groundwater
conditions. When data are not available, knowledge of the site
conditions and its history may contribute to arriving at a list of
contaminants and cost-effective analytical methods.
As with soils, the pH of groundwater and surface water is
important in determining the applicability of many treatment
processes. Often, the pH must be adjusted before or during a
treatment process. Low pH can interfere with chemical redox
processes. Extreme pH levels can limit microbial diversity and
hamper the application of both in situ and above-ground
applications of biological treatment [2, p. 97]. Contaminant
solubility and toxicity may be affected by changes in pH. The
species of metals and inorganics present are influenced by the
pH of the water, as are the type of phenolic, and nitrogen-
containing compounds present Processes such as carbon
adsorption, ion exchange, and ftocculation may be impacted
by pH changes [1, p. 5].
Eh helps to define, with pH, the state of oxidation-reduc-
tion equilibria in groundwater or aqueous waste streams. The
Eh must be below approximately 0.35 volts for significant
reductive chlorination to take place, but exact requirements
depend on the individual compounds being reduced. As
noted earlier in the soils section, maintaining anaerobksis (low
Eh) enhances decomposition of certain halogenated compounds
[23].
BOD, COD, and TOC measurements in contaminated
water, as in soils, provide indications of the biodegradable,
chemically oxidizable, or combustible fractions of the organic
contamination, respectively. These measurements are not in-
terchangeable, although correlations may sometimes be made
in order to convert the more precise TOC and/or COD mea-
surements to estimates of BOD. Interpretation of these data
should be made by an expert in the technologies being consid-
ered.
Oil and grease may be present in water to the extent that
they are the primary site contaminants. In that case, oil-water
separation may be called for as the principal treatment Even in
lower concentrations, oil and grease may still require pretreat-
ment to prevent clogging of ion exchange resins, activated
carbon systems, or other treatment system components [3, p.
91].
Suspended solids can cause resin binding in ion exchange
systems and clogging of reverse osmosis membranes, filtration
systems and carbon adsorption units. Suspended solids above
5 percent indicate that analysis of total and soluble metals
should be made [1, p. 14).
Standard analytical methods are used to identify the spe-
cific organic and inorgank contaminants. Properties of or-
ganic chemical contaminants important in treatment processes
include solubility in water, specific gravity, boiling point, and
vapor pressure. For the identified contaminants, these proper-
ties can generally be found in standard references [26] or in
EPA/RREL's Treatability Database [27].
Engineering Bulletin: technology Preselection Data Requirements
-------
Insoluble organic contaminants may be present as non-
aqueous phase liquids (NAPLs). DNAPLs will tend to sink to the
bottom of surface waters and groundwater aquifers. LNAPLs
will float on top of surface water and groundwater. In addition,
LNAPLs may adhere to the soil through the capillary fringe and
may be found on top of water in temporary or perched aquifers
in the vadose zone.
As noted previously, volatile organics may be in the form of
vapors in the pores of non-saturated soil, or they may be
dissolved in water. Even low-solubility organics may be present
at low concentrations dissolved in water. Some organics (e.g.
certain halogenated compounds, pesticides, and dioxins/furans
in water) resist biological treatment, while others may be ame-
nable to several technologies.
Dissolved metals may be found at toxic levels or levels
exceeding drinking water standards. Often they will require
chemical treatment The speciation of metals may be impor-
tant in determining the solubility, toxicity, and reactivity of
metal compounds.
Status of Data Requirements
The data requirements presented in Tables 1 and 2 are
based on currently available information. Preselection of new
and evolving technologies, or of currently used technologies
that have been modified, may require the collection of addi-
tional data. New analytical methods may be devised to replace
or supplement existing methods. Such improvements in ana-
lytical technology also could require additional data to be
collected. This bulletin may be updated if major changes occur
in data requirements for preselection of treatment technology
alternatives.
EPA Contact
Specific questions regarding technology preselection data
requirements may be directed to:
Eugene Harris
U.S. Environmental Protection Agency
Office of Research and Development
Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Gncinnati, Ohio 45268
(513)569-7862
Acknowledgments
This engineering bulletin was prepared for the U.S. Envi-
ronmental Protection Agency, Office of Research and Develop-
ment (ORD), Risk Reduction Engineering Laboratory (RREL),
Cincinnati, Ohio, by Science Applications International Corpo-
ration (SAIQ under EPA Contract No. 68-C8-0062. Mr. Eugene
Harris served as the EPA Technical Project Monitor. Mr. Gary
Baker was SAICs Work Assignment Manager. Mr. Jim Rawe
(SAIQ and Mr. Robert Hartley (SAIQ were the authors of the
bulletin.
The following other Agency and contractor personnel have
contributed their time and comments by participating in the
expert review meetings and/or peer reviewing the document:
Mr. Eric Sayior, SAIC
REFERENCES
1. A Compendium of Technologies Used in the Treatment
of Hazardous Wastes. EPA/625/8-87/014, U.S. Environ-
mental Protection Agency, Center for Environmental
Research Information, Gncinnati, OH, 1987.
2. Technology Screening Guide for Treatment of CERCLA
Soils and Sludges. EPA/540/2-88/004, U.S. Environmen-
tal Protection Agency, Office of Solid Waste and Emer-
gency Response, Washington, DC, 1988.
3. Guide for Conducting Treatability Studies Under CERCLA,
Interim Final. EPA/540/2-89/0058, U.S. Environmental
Protection Agency, Office of Solid Waste and Emergency
Response, Washington, D.C., 1989.
4. Guidance for Conducting Remedial Investigations and
Feasibility Studies Under CERCLA, Interim Final. EPA/540/
G-89/004, OSWER Directive 9355.3-01, U.S. Environ-
mental Protection Agency, Office of Solid Waste and
Emergency Response, Washington, D.C., 1988.
5. A Compendium of Superfund Field Operations Methods.
EPA/540/P-87/001, OSWER Directive 9355.0-14, U.S.
Environmental Protection Agency, Office of Solid Waste
and Emergency Response, Washington, D.C., 1987.
6. Breckenridge, R. P., J. R. Williams, and j. F. Keck. Ground
Water Issue: Characterizing Soils for Hazardous Waste Site
Assessments. EPA/540/4-91 /003, U.S. Environmental
Protection Agency. Office of Solid Waste and Emergency
Response, Washington, D.C., 1991.
7. American Society of Agronomy, Inc. Methods of Soil
Analysis, Part 2, Chemical and Microbiological Properties,
Second Edition, 1982.
8. NIOSH. Manual of Analytical Methods, Third Edition
1984.
9. Methods for the Chemical Analysis of Water and Wastes.
EPA/600/4-79/020, U.S. Environmental Protection
Agency, Office of Research and Development, Washing-
ton, D.C., 1983.
Engineering Bulletin: Technology Preselection Data Requirements
•U.S. Govwnmn
1002— 648-OKMOOge
-------
10. American Society for Testing and Materials. Annual Book
of ASTM Standards, 1987.
11. Test Methods for Evaluating Solid Waste. Third Edition.
SW-846, U.S. Environmental Protection Agency, Office of
Solid Waste and Emergency Response, Washington, D.C
1986.
12. Data Quality Objective for Remedial Response Activities,
Example Scenario: RI/FS Activities at a Site with Contami-
nated Soils and Ground Water. EPA/540/G-87/004,
OSWER Directive 9355.0-7B, U.S. Environmental Protec-
tion Agency Office of Solid Waste and Emergency
Response, Washington, D.C, 1987.
13. Engineering Bulletin: Soil Washing Treatment, U.S.
Environmental Protection Agency, EPA/540/2-90/017.
Office of Emergency and Remedial Response, Washing-
ton, D.C. and Office of Research and Development,
Cincinnati, OH, 1990.
14. Summary of Treatment Technology Effectiveness for
Contaminated Soil. EPA/540/2-89/053, U.S. Environmen-
tal Protection Agency. Office of Emergency and Remedial
Response, Washington, D.C, 1991.
15. Engineering Bulletin: Thermal Desorption Treatment
EPA/540/2-91/008, U.S. Environmental Protection
Agency, Office of Emergency and Remedial Response,
Washington, D.C and Office of Research and Develop-
ment, Gnrinnati, OH, 1991.
16. Engineering Bulletin: In-Situ Steam Extraction Treatment
EPA/540/2-91/005, U.S. Environmental Protection
Agency, Office of Emergency and Remedial Response,
Washington, D.C and Office of Research and Develop-
ment, Cincinnati, OH, 1991.
17. Engineering Bulletin: In-Situ Soil Vapor Extraction
Treatment EPA/540/2-91/006, U.S. Environmental
Protection Agency. Office of Emergency and Remedial
Response, Washington, D.C. and Office of Research and
Development, Cincinnati, OH, 1991.
18. Engineering Bulletin: Slurry Biodegradation. EPA/540/2-
90/016, U.S. Environmental Protection Agency, Office of
Emergency and Remedial Response, Washington, D.C
and Office of Research and Development, Cincinnati, OH,
1990.
19. Handbook for Stabilization/Solidification of Hazardous
Wastes. EPA/540/2-90/001, U.S. Environmental Protec-
tion Agency, Office of Emergency and Remedial Re-
sponse, Washington, D.C., 1986.
20. Engineering Bulletin: Mobile/Transportable incineration
Treatment EPA/540/2-90/014, U.S. Environmental
Protection Agency, Office of Emergency and Remedial
Response, Washington, D.C. and Office of Research and
Development, Cincinnati, OH, 1990.
21. Superfund Engineering Issue: Issues affecting the
Applicability and Success of Remedial/Removal Incinera-
tion Projects. EPA/540/2-91/004, U.S. Environmental
Protection Agency, Office of Emergency and Remedial
Response, Washington, D.C. and Office of Research and
Development, Cincinnati, OH, 1991.
22. Handbook on In-Situ Treatment of Hazardous Waste-
Contaminated Soils. EPA/540/2-90/002, U.S. Environ-
mental Protection Agency, Risk Reduction Engineering
Laboratory, Cincinnati, OH, 1990.
23. Koboyashi, H. and B. L Rittman. Microbial Removal of
Hazardous Organic Compounds. Environmental Science
and Technology, 16:170A-183A, 1982.
24. Engineering Bulletin: Chemical Dehalogenation Treat-
ment APEC Treatment EPA/540/2-90/015, U.S.
Environmental Protection Agency, Office of Emergency
and Remedial Response, Washington, D.C. and Office of
Research and Development, Cincinnati, OH, 1990.
25. Engineering Bulletins: Chemical Oxidation Treatment
EPA/540/2-91/025, U.S. Environmental Protection
Agency, Office of Emergency and Remedial Response,
Washington, D.C. and Office of Research and Develop-
ment, Cincinnati, OH, 1991.
26. Budavari, S., ed. The Merck Index, 11 th Edition. Merck
& Company, Inc., Rathway, NJ, 1989.
27. US Environmental Protection Agency RREL Treatability
Data Base. Computer disk available from Risk Reduction
Engineering Laboratory, Cincinnati, OH, 1990.
Engineering Bulletin: Technology Preselection Data Requirements
-------
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/540/S-92/009
-------
Section 4
-------
GENERAL RESPONSE ACTIONS
STUDENT PERFORMANCE OBJECTIVES
At the conclusion of this unit, students will be able to:
1. Describe four containment operations
2. Describe four recovery operations
3. List five sources of information for soil and groundwater
conditions that are reviewed during a site investigation
4. List four types of nonintrusive tools that can be used to
gather geophysical field data
5. Describe the function and placement of groundwater
containment walls
6. Describe the concept of hydrodynamic control
7. List six site preparation activities
8. List two techniques and two types of equipment used to
handle drums during a removal operation
9. Describe the difference between RCRA characteristic and
listed wastes
NOTE: Unless otherwise stated, the conditions for
performance are using all references and materials
provided in the course, and the standards of
performance are without error.
7/95
-------
STUDENT PERFORMANCE OBJECTIVES (cont.)
10. Describe the difference between concentration-based
standards and required technology treatment standards for
hazardous waste
11. Describe the step necessary to meet shipping requirements
for a hazardous waste.
NOTE: Unless otherwise stated, the conditions for
performance are using all references and materials
provided in the course, and the standards of
performance are without error.
General Response Actions 7/95
-------
NOTES
GENERAL
RESPONSE
ACTIONS
8-1
GENERAL RESPONSE ACTIONS
• Containment and recovery
• Site investigation
• Site preparation
• Groundwater control
• Drum removal
CONTAINMENT
Plugging
Damming
Booming
Diking
Absorbing
8-2
S-3
7/95
General Response Actions
-------
NOTES
Overflow Dam
RECOVERY
Sweeping
Skimming
Pumping
Ground Penetration
S-5
s-e
General Response Actions
7/95
-------
LNAPL Recovery
LNAPL skimming system
Water pumping system
8-7
INFORMATION SOURCES
• U.S. and state geological surveys
• Soil conservation services
• University research
• Site records
• Aerial photography
• Site reconnaissance
S-t
GEOPHYSICS
Electromagnetics
Resistivity
Seismic
Ground penetrating radar
8-8
NOTES
U>
7/P5
General Response Actions
-------
/VOTES
GROUNDWATER CONTROL
• Slurry trench cutoff walls
• Grout curtains
• Sheet piling
• Hydrodynamic control
8-10
Slurry Trench Cutoff Wall Monitoring Production
1 well well
\::::::::::::::::::::::TTrx
\' • V ( v-\A|dP \
N^: : : : :$>NVr!T : ::::::::::/
Groundwater
flow
Slurr
cute
Aquitard
I
/ tr<
>ff w
— —
inch
tall
=
"~ >»
•^ '
y
==
^
Ml
Keved-in Wall
1
Monitoring
well
Production
well
Aquitard
8-12
General Response Actions
7/95
-------
NOTES
Hanging Wall
LNAPLs
Recovery
well
Monitoring
well
Production
well
Groundwater
flow
Aquitard
8-13
Upgradient Wall
Drain
8-14
Downgradient Wall
7/95
General Response Actions
-------
NOTES
Soil
Grout
curtain
Grout Curtain
Injection tube
GROUT INJECTION
Injection Tube
Zone of Influence
3-16
8-17
Steel Piling Shapes and Interlocks
General Response Actions
7/95
-------
\
Connecting piping
Plume
Groundwater
flow
Hydrodynamic Control System
SITE PREPARATION
Access roads
Grading and leveling
Concrete bases or pads
Spill control
Site security
UTILITIES
• Process water
• Electric power
• Auxiliary fuel
8-10
S-20
S-21
NOTES
-7
7/95
General Response Actions
-------
NOTES
SUPPORT SYSTEMS
Fuel storage and delivery
Waste storage and containment
Soil preparation and handling
CHARACTERISTIC WASTES
Ignitable (0001)^-
Corrosive (D002)
Reactive (D003)
Heavy metals (D004-D011)
Pesticides (D012-D017)
Organics (D018-D043)
LISTED WASTES
8-22
3-23
Nonspecific sources (solvents,
F001-F005)
Specific sources (wood preservation,
K001)
Poisons (cyanides, N.O.S. P030)
Unused products (acetone, U002)
8-24
General Response Actions
7/95
-------
NOTES
TREATMENT STANDARDS
• Concentration based
• Treatment based —
8-25
CONCENTRATION BASED
Best demonstrated available technology
(BOAT) or other
Treatment residue at specified values
before land disposal
8-20
TREATMENT BASED
Treatment method(s) are specified and
MUST be used before land disposal
S-27
7/95
General Response Actions
-------
NOTES
SHIPPING REQUIREMENTS
• In accordance with DOT HM-181
• Approved Hazwaste hauler
• Manifest required
• Labeling and packaging required
• Notification and certification may be
required
S-28
General Response Actions
10
7/95
-------
REFERENCES
U.S. EPA. 1985. Technology Transfer Handbook: Remedial Action at Waste Disposal Sites
(Revised). EPA/625/6-85/006. U.S. Environmental Protection Agency, Office of Research and
Development, Hazardous Waste Engineering Research Laboratory, Cincinnati, OH.
U.S. EPA. 1986. Drum Handling Practices at Hazardous Waste Sites. EPA/600/2-86/013. U.S.
Environmental Protection Agency, Office of Research and Development, Hazardous Waste
Engineering Research Laboratory, Cincinnati, OH.
U.S. EPA. 1990. Cylinder Recovery Vessel (CRV). Videotape. U.S. Environmental Protection
Agency, Chemical Control National Priority List site, Elizabeth, NJ.
U.S. EPA. 1992a. Engineering Bulletin: Slurry Walls. EPA/540/S-92/008. U.S. Environmental
Protection Agency, Office of Research and Development, Risk Reduction Engineering Laboratory,
Cincinnati, OH.
U.S. EPA. 1992b. Technical Guidance Document: Construction Quality Management for Remedial
Action and Remedial Design Waste Containment Systems. U.S. Environmental Protection Agency,
Office of Solid Waste and Emergency Response, Washington, DC.
7/95 11 General Response Actions
-------
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U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
Public Health Service
Centers for Disease Control
National Institute for Occupational Safety and Health
-------
11. Handling Drums and Other Containers
Contents
Introduction 11-1
Inspection 11-1
Planning 11-3
Handling 11-3
Drums Containing Radioactive Waste 11-4
Drums that May Contain Explosive or Shock-
Sensitive Wastes 11-4
Bulging Drums 11-4
Drums Containing Packaged Laboratory Wastes
(Lab Packs) 11-4
Leaking, Open, and Deteriorated Drums 11-4
Buried Drums 11-5
Opening 11-5
Sampling 11-6
Characterization 11-7
Staging 11-8
Bulking 11-9
Shipment 11-9
Special Case Problems 11-11
Tanks and Vaults 11-11
Vacuum Trucks 11-12
Elevated Tanks 11-12
Compressed Gas Cylinders 11-12
Ponds and Lagoons 11-12
References 11-12
Introduction
Accidents may occur during handling of drums and other
hazardous waste containers. Hazards include detonations,
fires, explosions, vapor generation, and physical injury
resulting from moving heavy containers by hand and
working around stacked drums, heavy equipment, and
deteriorated drums. While these hazards are always pres-
ent, proper work practices—such as minimizing handling
and using equipment and procedures that isolate workers
from hazardous substances —can minimize the risks to
site personnel.
This chapter defines practices and procedures for safe
handling of drums and other hazardous waste containers.
It is intended to aid the Project Team Leader in setting up
a waste container handling program. In addition to read-
ing this chapter, the Project Team Leader should also be
aware of all pertinent regulations. OSHA regulations (29
CFR Pans 1910 and 1926) include general requirements
and standards for storing, containing, and handling chem-
icals and containers, and for maintaining equipment used
for handling materials. EPA regulations (40 CFR Part 265)
stipulate requirements for types of containers, main-
tenance of containers and containment structures, and
design and maintenance of storage areas. DOT regula-
tions (49 CFR Parts 171 through 178) also stipulate
requirements for containers and procedures for shipment
of hazardous wastes.
Containers are handled during characterization and
removal of their contents and during other operations. A
flow chan showing one set of possible procedures for
drum handling is given in Figure 11-1. Guidance for safely
performing the procedures shown in Figure 11-1 is
provided in the following sections of this chapter. The
final section, Special Case Problems, describes the
handling of tanks, vaults, vacuum trucks, elevated tanks,
and compressed gas cylinders.
Inspection
The appropriate procedures for handling drums depend on
the drum contents. Thus, prior to any handling, drums
should be visually inspected to gain as much information
as possible about their contents. The inspection crew
should look for:
• Symbols, words, or other marks on the drum indicat-
ing that its contents are hazardous, &g., radioactive,
explosive, corrosive, toxic, flammable
• Symbols, words, or other marks on a drum indicating
that it contains discarded laboratory chemicals, rea-
gents, or other potentially dangerous materials in
small-volume individual containers (see Table 11-1).
• Signs of deterioration such as corrosion, rust, and
leaks.
• Signs that the drum is under pressure such as swell-
ing and bulging.
• Drum type (see Table 11-1).
• Configuration of the drumhead (see Table 11-2).
Conditions in the immediate vicinity of the drums may
provide information about drum contents and their
associated hazards. Monitoring should be conducted
around the drums using instruments such as a gamma
radiation survey instrument, organic vapor monitors, and
a combustible gas meter.
The results of this survey can be used to classify the
drums into preliminary hazard categories, for example:
• Radioactive.
• Leaking/deteriorated.
• Bulging.
• Explosive/shock-sensitive.
• Contains small-volume individual containers of
laboratory wastes or other dangerous materials.
As a precautionary measure, personnel should assume
that unlabelled drums contain hazardous materials until
their contents are characterized. Also, they should bear in
mind that drums are frequently mislabelled—particularly
drums that are reused. Thus, a drum's label may not
accurately describe its contents.
If buried drums are suspected, ground-penetrating sys-
tems, such as electromagnetic wave, electrical resistivity,
ground-penetrating radar, magnetometry, and metal
detection, can be used to estimate the location and depth
of the drums.
-------
11-2
Handling Drums and Other Containers
INSPECTION
Inspect drums
'
^f
^r Han
^^^ neces
i
r
^^
NO
^
•^
cc _X^ ^S^ vcc PLANNING
=*X^ Staging ^SJ*? _ ,
-*~V^ necessary? ^— ** Develop a
^^^ ^^ staging plan
^>
\
r™ i
PLANNING STAGING
Develop a ,Move drums to
handling plan *"* Sta9'n9 area
• (if appropriate)
>
OPENING
Open drums
i
r
SAMPLING
Develop sampling
plan. Sample
drum contents
\
F
CHARACTERIZATION
Characterize wastes
\
r
BULKING
Transfer drum
contents into
bulk containers
\
r w
HANDLING Move drums to C
Orient drums opening/sampling ^
for opening area 0
and sampling (if appropriate)
\
r_J_ n ,
Move drums to ( S
second staging i
area Sample
(if appropriate) .
r_:i:_n
Move drums to CHAR/
final staging area !«*—
(if appropriate) 1 Cnara
1
BULKING
Transfer drum
contents into
bulk containers
r
IPENING
pen drums
\ '
AMPLING
9 drum contents
V
kCTERIZATION
cterize wastes
SHIPMENT
Ship bulked wastes and /or
drums to offsite treatment,
storage, or disposal facility
Figure 11-1. Flow Chart for Drum Handling. (Dashed boxes indicate optional steps.
Number of staging areas necessary is site specific.)
-------
Handling Drums and Other Containers
11-3
Table 11-1. Special Drum Types and
Their Associated Hazards
Polyethylene or
PVC-Uned Drum*
Exotic Metal
Drums lag., alumi-
num, nickel, stain-
less, steel, or other
unusual metal)
Single-Walled
Drums Used as a
Pressure Vessel
Laboratory Packs
Often contain strong acids or bases. If the
lining is punctured, the substance usually
quickly corrodes the steel, resulting in a
significant leak or spill.
Very expensive drums that usually con-
tain an extremely dangerous material.
These drums have fittings for both
product filling and placement of an inert
gas, such as nitrogen. May contain reac-
tive, flammable, or explosive substances.
Used for disposal of expired chemicals
and process samples from university
laboratories, hospitals, and similar institu-
tions. Individual containers within the lab
pack are often not packed in absorbent
material. They may contain incompatible
materials, radioisotopes, shock-sensitive,
highly volatile, highly corrosive, or very
toxic exotic chemicals. Laboratory packs
can be an ignition source for fires at
hazardous waste sites.
Table 11-2. Information Provided by
Drumhead Configuration
CONFIGURATION
INFORMATION
Whole lid removable.
Has a bung.
Contains a liner.
Designed to contain solid
material.
Designed to contain a liquid.
May contain a highly corrosive
or otherwise hazardous material.
Planning
Since drum handling is fraught with danger, every step of
the operation should be carefully planned, based on all
the information available at the time. The results of the
preliminary inspection can be used to determine (1) if any
hazards are present and the appropriate response, and
(2) which drums need to be moved in order to be opened
and sampled. A preliminary plan should be developed
which specifies the extent of handling necessary, the per-
sonnel selected for the job, and the most appropriate
procedures based on the hazards associated with the
probable drum contents as determined by visual inspec-
tion. This plan should be revised as new information is
obtained during drum handling.
to facilitate characterization and remedial action (see
Staging in this chapter). Handling may or may not be
necessary, depending on how the drums are positioned at
a site.
Since accidents occur frequently during handling, particu-
larly initial handling, drums should only be handled if
necessary. Prior to handling, all personnel should be
warned about the hazards of handling, and instructed to
minimize handling as much as possible and to avoid
unnecessary handling. In all phases of handling, person-
nel should be alert for new information about potential
hazards. These hazards should be responded to before
continuing with more routine handling operations. Over-
pack drums (larger drums in which leaking or damaged
drums are placed for storage or shipment (see 49 CFR
Part 173.3(c)]j and an adequate volume of absorbent
should be kept near areas where minor spills may occur.
Where major spills may occur, a containment berm ade-
quate to contain the entire volume of liquid in the drums
should be constructed before any handling takes place. If
the drum contents spill, personnel trained in spill response
should be used to isolate and contain the spill.
Several types of equipment can be used to move drums:
(1) A drum grappler attached to a hydraulic excavator;
(2) a small front-end loader, which can be either loaded
manually or equipped with a bucket sling; (3) a rough ter-
rain forklift; (4) a roller conveyor equipped with solid
rollers; and (5) drum carts designed specifically for drum
handling. Drums are also sometimes moved manually. The
drum grappler is the preferred piece of equipment for
drum handling. It keeps the operator removed from the
drums so that there is less likelihood of injury if the drums
detonate or rupture If a drum is leaking, the operator can
stop the leak by rotating the drum and immediately plac-
ing it into an overpack. In case of an explosion, grappler
claws help protect the operator by partially deflecting the
force of the explosion.
Backhoe with drum grappler.
Handling
The purpose of handling is to (1) respond to any obvious
problems that might impair worker safety, such as radio-
activity, leakage, or the presence of explosive substances,
(2) unstack and orient drums for sampling, and (3) if
necessary, to organize drums into different areas on site
The following procedures can be used to maximize
worker safety during drum handling and movement:
• Train personnel in proper lifting and moving tech-
niques to prevent back injuries.
• Make sure the vehicle selected has sufficient rated
load capacity to handle the anticipated loads, and
-------
11-4
Handling Drums and Other Containers
make sure the vehicle can operate smoothly on the
available road surfaca
• Air condition the cabs of vehicles to increase opera-
tor efficiency; protect the operator with heavy splash
shields.
• Supply operators with appropriate respiratory protec-
tive equipment when needed. Normally either a com-
bination SCBA/SAR with the air tank fastened to the
vehicle, or an airline respirator and an escape SCBA
are used because of the high potential hazards of
drum handling. This improves operator efficiency and
provides protection in case the operator must aban-
don the equipment.
• Have overpacks ready before any attempt is made to
move drums.
• Before moving anything, determine the most appro-
priate sequence in which the various drums and
other containers should be moved. For example, small
containers may have to be removed first to permit
heavy equipment to enter and move the drums.
• Exercise extreme caution in handling drums that are
not intact and tightly sealed.
• Ensure that operators have a clear view of the road-
way when carrying drums. Where necessary, have
ground workers available to guide the operator's
motion.
Drums Containing Radioactive Waste
• If the drum exhibits radiation levels above back-
ground (see Table 6-2), immediately contact a health
physicist. Do not handle any drums that are deter-
mined to be radioactive until persons with expertise
in this area have been consulted.
Drums that May Contain Explosive or
Shock-Sensitive Waste
• If a drum is suspected to contain explosive or shock-
sensitive waste as determined by visual inspection,
seek specialized assistance before any handling.
• If handling is necessary, handle these drums with
extreme caution.
• Prior to handling these drums, make sure all non-
essential personnel have moved a safe distance away.
• Use a grappler unit constructed for explosive contain-
ment for initial handling of such drums.
• Palletize the drums prior to transport. Secure drums
to pallets.
• Use an audible siren signal system, similar to that
employed in conventional blasting operations, to
signal the commencement and completion of explo-
sive waste handling activities.
• Maintain continuous communication with the Site
Safety Officer and/or the command post until drum
handling operations are completa
Bulging Drums
• Pressurized drums are extremely hazardous. Wher-
ever possible, do not move drums that may be
under internal pressure, as evidenced by bulging or
swelling.
• If a pressurized drum has to be moved, whenever
possible handle the drum with a grappler unit con-
structed for explosive containment. Either move
the bulged drum only as far as necessary to allow
seating on firm ground, or carefully overpack the
drum. Exercise extreme caution when working
with or adjacent to potentially pressurized drums.
Drums Containing Packaged Laboratory Wastes
(Lab Packs)
Laboratory packs (i.a, drums containing individual con-
tainers of laboratory materials normally surrounded by
cushioning absorbent material) can be an ignition source
for fires at hazardous waste sites. They sometimes con-
tain shock-sensitive materials. Such containers should be
considered to hold explosive or shock-sensitive wastes
until otherwise characterized. If handling is required, the
following precautions are among those that should be
taken:
• Prior to handling or transporting lab packs, make sure
all non-essential personnel have moved a safe dis-
tance away.
• Whenever possible, use a grappler unit constructed
for explosive containment for initial handling of such
drums.
• Maintain continuous communication with the Site
Safety Officer and/or the command post until han-
dling operations are complete.
• Once a lab pack has been opened, have a chemist
inspect, classify, and segregate the bottles within it,
without opening them, according to the hazards of
the wastes. An example of a system for classifying
lab pack wastes is provided in Table 11-3. The objec-
tive of a classification system is to ensure safe segre-
gation of the lab packs' contents. Pack these bottles
with sufficient cushioning and absorption materials
to prevent excessive movement of the bottles and to
absorb all free liquids, and ship them to an approved
disposal facility.
• If crystalline material is noted at the neck of any
bottle, handle it as a shock-sensitive waste, due to
the potential presence of picric acid or other similar
material, and get expert advice before attempting to
handle it.
• Palletize the repacked drums prior to transport.
Secure the drums to pallets.
Leaking, Open, and Deteriorated Drums
• If a drum containing a liquid cannot be moved with-
out rupture, immediately transfer its contents to a
sound drum using a pump designed for transfering
that liquid.
• Using a drum grappler, place immediately in overpack
containers:
Leaking drums that contain sludges or semi-solids.
Open drums that contain liquid or solid wasta
Deteriorated drums that can be moved without
rupture.
-------
Handling Drums and Other Containers
11-5
Table 11-3. Example of Lab Pack Content Classification
System for Disposal
CLASSIFICATION
EXAMPLES
Inorganic acids
Inorganic bases
Strong oxidizing agents
Strong reducing agents
Anhydrous organics and
organometallics
Anhydrous inorganics and
metal hydrides
Toxic organics
Flammable organics
Inorganics
Inorganic cyanides
Organic cyanides
Toxic metals
Hydrochloric
Sulfuric
Sodium hydroxide
Potassium hydroxide
Ammonium nitrate
Barium nitrate
Sodium chlorate
Sodium peroxide
Sodium thiosulfate
Oxalic acid
Sodium sulphite
Tetraethyl lead
Phenylmercuric chloride
Potassium hydride
Sodium hydride
Sodium metal
Potassium
PCBs
Insecticides
Hexane
Toluene
Acetone
Sodium carbonate
Potassium chloride
Potassium cyanide
Sodium cyanide
Copper cyanide
Cyanoacetamide
Arsenic
Cadmium
Lead
Mercury
Buried Drums
• Prior to initiating subsurface excavation, use ground-
penetrating systems to estimate the location and
depth of the drums (see Inspection in this chapter).
• Remove soil with great caution to minimize the
potential for drum rupture
• Have a dry chemical fire extinguisher on hand to con-
trol small fires.
Opening
Drums are usually opened and sampled in place during
site investigations. However, remedial and emergency
operations may require a separate drum opening area (see
Staging in this chapter). Procedures for opening drums
are the same, regardless of where the drums are opened.
To enhance the efficiency and safety of drum-opening
personnel, the following procedures should be instituted.
• If a supplied-air respiratory protection system is used,
place a bank of air cylinders outside the work area
and supply air to the operators via airlines and
escape SCBAs. This enables workers to operate in
relative comfort for extended periods of time.
• Protect personnel by keeping them at a safe distance
from the drums being opened. If personnel must be
located near the drums, place explosion-resistant
plastic shields between them and the drums to pro-
tect them in case of detonation. Locate controls for
drum opening equipment, monitoring equipment, and
fire suppression equipment behind the explosion-
resistant plastic shield.
• If possible, monitor continuously during opening.
Place sensors of monitoring equipment, such as
colorimetric tubes, dosimeters, radiation survey
instruments, explosion meters, organic vapor
analyzers, and oxygen meters, as close as possible
to the source of contaminants, i.e., at the drum
opening.
• Use the following remote-controlled devices for
opening drums:
Pneumatically operated impact wrench to remove
drum bungs.
Hydraulically or pneumatically operated drum
piercers (see Figure 11-2).
Backhoes equipped with bronze spikes for
penetrating drum tops in large-scale operations
(see Figure 11-3).
• Do not use picks, chisels and firearms to open
drums.
• Hang or balance the drum opening equipment to
minimize worker exertion.
• If the drum shows signs of swelling or bulging,
perform all steps slowly. Relieve excess pressure
prior to opening and, if possible, from a remote
location using such devices as a pneumatic impact
wrench or hydraulic penetration device If pressure
must be relieved manually, place a barrier such as
explosion-resistant plastic sheeting between the
worker and bung to deflect any gas, liquid, or
solids which may be expelled as the bung is
loosened.
Two drums with rusted bungs were opened by backhoes
with bronze spikes and now await sampling. Drum in fore-
ground has been labelled "150" for sample documenta-
tion purposes.
-------
11-6
Handling Drums and Other Containers
REMOTE
LOCATION
NEEDLE VALVE
AIR/HYDRAULIC CYLINDER
55 GAL. DRUM
CONVEYOR
3-WAY VALVE
APPROX. 50 FT. OF HOSE
SPLASH PLATE
REPLACEABLE 316 STAINLESS
STEEL CONICAL PLUNGER
(3 IN. DIA. X 4 IN. LG.)
DOORS (2 SIDES)
BELT CONVEYOR
DRAIN TO VACUUM TRUCK,
WASTE RECOVERY SYSTEM
OR TANK
FORK LIFT SLOTS
SPILL CONTAINMENT PAN &
SUPPORT FRAME (75-GAL CAPACITY)
Figure 11-2. Air/Hydraulic-Operated Single-Drum Puncture Device.
Source: Reference [1].
• Open exotic metal drums and polyethylene or
polyvinyl chloride-lined (PVC-lined) drums through
the bung by removal or drilling. Exercise extreme
caution when manipulating these containers.
• Do not open or sample individual containers within
laboratory packs.
• Reseal open bungs and drill openings as soon as
possible with new bungs or plugs to avoid explo-
sions and/or vapor generation. If an open drum
cannot be reseated, place the drum into an over-
pack. Plug any openings in pressurized drums with
pressure-venting caps set to a 5-psi (pounds per
square inch) release to allow venting of vapor
pressure.
Decontaminate equipment after each use to avoid
mixing incompatible wastes.
Sampling
Drum sampling can be one of the most hazardous activi-
ties to worker safety and health because it often involves
direct contact with unidentified wastes. Prior to collecting
any sample, develop a sampling plan:
• Research background information about the waste.
• Determine which drums should be sampled.
• Select the appropriate sampling device(s) and
container(s).
-------
Handling Drums and Other Containers
11-7
REPLACEABLE 316 STAINLESS
HYDRAULIC CYL
WITH 6-IN. STROKE
SPLASH PLATE
STANDARD SINGLE
DRUM GRABBER
STEEL CONICAL PLUNGER
(3 IN. DIA. X 4 IN. LG.)
BACKHOE
ARM (REF.)
ADAPTER BRACKET
SPILL CONTAINMENT PAN
(PORTABLE) 75-GAL CAPACITY
55-GALLON
- DRUM
HYDRAULIC LINES
DRAIN TO VACUUM TRUCK, WASTE
RECOVERY SYSTEM OR TANK
Figure 11-3. Backhoe-Mounted Drum Puncture Device.
Source: Reference ID.
• Develop a sampling plan which includes the number,
volume, and locations of samples to be taken.
• Develop Standard Operating Procedures for opening
drums, sampling, and sample packaging and trans-
portation. Some guidance in designing proper
sampling procedures can be found in References [2]
and [31.
• Have a trained health and safety professional deter-
mine, based on available information about the
wastes and site conditions, the appropriate personal
protection to be used during sampling, decontamina-
tion, and packaging of the sample.
When manually sampling from a drum, use the following
techniques:
• Keep sampling personnel at a safe distance while
drums are being opened. Sample only after opening
operations are complete.
• Do not lean over other drums to reach the drum being
sampled, unless absolutely necessary.
• Cover drum tops with plastic sheeting or other suit-
able noncontaminated materials to avoid excessive
contact with the drum tops.
• Never stand on drums. This is extremely dangerous.
Use mobile steps or another platform to achieve the
height necessary to safely sample from the drums.
• Obtain samples with either glass rods or vacuum
pumps. Do not use contaminated items such as dis-
carded rags to sample. The contaminants may con-
taminate the sample and may not be compatible with
the waste in the drum. Glass rods should be removed
prior to pumping to minimize damage to pumps.
Characterization
The goal of characterization is to obtain the data neces-
sary to determine how to safely and efficiently package
and transport the wastes for treatment and/or disposal.
If wastes are bulked, they must be sufficiently character-
-------
11-8
Handling Drums and Other Containers
SITE:
DRUM SIZE:
0 unknown
1 55 gal.
2 30 gal._
3 other
specify
DRUM NO. SAMPLE NO.
DRUM OPENING: DRUM TYPE:
0
1
2
3
4
unknown 0
ring top 1
closed top 2
open top 3
other 4
specify __ 5
unknown
metal
plastic
fiber
glass
other
specify
DRUM COLOR:
0 unknown
1 cream
2 clear
3 black
4 white
5 red
6 green
7 blue
8 brown
9 pink
10 orange
11 yellow
12 gray
13 purple
14 amber
PR1
^^««,
SEC
^m~~m
15 green-blue
DRUM CONTENTS COLOR:
0 unknown
1 creaa
2 clear
3 black
4 white
5 red
6 green
7 blue
8 brown
9 pink
10 orange
11 yellow
12 gray
13 purple
14 anbei
15 green-blue
DRUM CONDITION:
0 unknown
1 good
2 fair
3 poor __
DRUM MARKING KEYWORD
DRUM MARKING KEYWORD
DRUM MARKING KEYWORD
DRUM CONTENTS STATE:
0 unknown
1 solid
2 liquid
3 sludge
4 gas
5 trash
6 dirt
7 gel
DRUM CONTENT AMOUNT:
0 unknown
1 full '
2 part
3 e«Pty
CHEMICAL ANALYSIS:
radiation
igol table
water reactive
cyanide
oxidlzer
organic vapor
pH
1
2
3
PRI SEC
YES NO
__
SCREENING RESULTS
0 unknown
1 radioactive
2 acid/oxidixer
(AREA):
3 caustic/reducer/cyanide
4 flammable organic
5 nonflammable organic
6 peroxide
7 air or water reactive
8 inert
SCREENING DATA:
YES NO
RADIOACTIVE
ACIDIC
CAUSTIC
AIR REACTIVE
WATER REACTIVE
WATER SOLUBLE
WATER BATH OVA
COMBUSTIBLE
BALIDE
INORGANIC
ORGANIC
ALCOHOL/ ALDEHYDE
CYANIDE
FLAMMABLE
OXIDIZER
INERT OR OTHER
___
> 1 mR over background
pH < 3
pH > 12
Reaction of > 10* F
temp, change
Reaction of £ 10° F
temp, change'
Dissolves In water
Reading »
^ 10 ppm - Yes
Catches fire when
torched In water bath
Green flame when
heated with copper
WATER BATH OVA and
COMBUSTIBLE - No
INORGANIC - No
WATER BATH OVA,
WATER SOLUBLE and
COMBUSTIBLE • Yes
Draeger tube over
water bach > 2 ppm
COMBUSTIBLE • Yes, and
SETA flashpoint £ 140° F
Starch' iodine paper
•hows positive reaction
Everything "No" except
INORGANIC or ORGANIC
PP»
Figure 11-4. Sample Drum Characterization Sheet.
Source: EPA Region VII Emergency Planning and Response Branch.
(This figure is provided only as an example Values were selected
by EPA Region VII and should be modified as appropriate.)
ized to determine which of them can be safely combined
(see Bulking later in this chapter). As a first step in
obtaining these data, standard tests should be used to
classify the wastes into general categories, including
auto-reactives, water reactives, inorganic acids, organic
acids, heavy metals, pesticides, cyanides, inorganic
oxidizers, and organic oxidizers. In some cases, further
analysis should be conducted to more precisely identify
the waste materials. See Figure 11-4 for an example of a
characterization sheet for drums.
When possible, materials should be characterized using
an onsite laboratory. This provides data as rapidly as pos-
sible, and minimizes the time lag before appropriate action
can be taken to handle any hazardous materials. Also, it
precludes any potential problems associated with trans-
porting samples to an offsite laboratory (eg., sample
packaging, waste incompatibility, fume generation).
If samples must be analyzed off site, samples should be
packaged on site in accordance with DOT regulations
(49 CFR) and shipped to the laboratory for analysis.
Staging
Although every attempt should be made to minimize drum
handling, drums must sometimes be staged (\A. moved in
an organized manner to predesignated areas) to facilitate
characterization and remedial action, and to protect
-------
Handling Drums and Other Containers
11-9
drums from potentially hazardous site conditions (e^j.,
movement of heavy equipment and high temperatures
that might cause explosion, ignition, or pressure buildup).
Staging involves a trade-off between the increased haz-
ards associated with drum movement and the decreased
hazards associated with the enhanced organization and
accessibility of the waste materials.
The number of staging areas necessary depends on site-
specific circumstances such as the scope of the opera-
tion, the accessibility of drums in their original positions,
and the perceived hazards. Investigation usually involves
little, if any, staging; remedial and emergency operations
can involve extensive drum staging. The extent of staging
must be determined individually for each site, and should
always be kept to a minimum. Up to five separate areas
have been used (see Figure 11-5):
• An initial staging area where drums can be
(1) organized according to type, size, and sus-
pected contents, and (2) stored prior to sampling.
• An opening area where drums are opened,
sampled, and reseated. Locate this area a safe dis-
tance from the original waste disposal or storage
site and from all staging areas to prevent a chain
reaction in case of fire or explosion.
• During large-scale remedial or emergency tasks, a
separate sampling area may be set up at some dis-
tance from the opening area to reduce the number
of people present in the opening area, and to limit
potential casualties in case of an explosion.
• A second staging area, also known as a holding
area, where drums are temporarily stored after
sampling pending characterization of their con-
tents. Do not place unsealed drums with unknown
contents in the second staging area in case they
contain incompatible materials. (Either remove the
contents or overpack the drum.)
• A final staging area, also known as a bulking area,
where substances that have been characterized
are bulked for transport to treatment or disposal
facilities.
Locate the final staging area as close as possible to
the site's exit.
Grade the area and cover it with plastic sheeting.
Construct approximately 1-foot-high (0.3-m-high)
dikes around the entire area.
Segregate drums according to their basic chemical
categories (acids, heavy metals, pesticides, etc.) as
determined by characterization. Construct separate
areas for each type of waste present to preclude
the possibility of intermingling incompatible chemi-
cals when bulking.
In all staging areas, stage the drums two wide in two
rows per area (see Figure 11-6), and space these rows
7 to 8 feet (2 to 2.5 m) apart to enable movement of the
drum handling equipment.
Bulking
Wastes that have been characterized are often mixed
together and placed in bulk containers such as tanks or
vacuum trucks for shipment to treatment or disposal
Crushed drums awaiting landfill. Note the staging of
drums on the left in a row two drums wide.
facilities. This increases the efficiency of transportation.
Bulking should be performed only after thorough waste
characterization by trained and experienced personnel.
The preliminary tests described earlier under Characteriza-
tion provide only a general indication of the nature of the
individual wastes. In most cases, additional sampling and
analysis to further characterize the wastes, and compati-
bility tests (in which small quantities of different wastes
are mixed together under controlled conditions and
observed for signs of incompatibility such as vapor gener-
ation and heat of reaction) should be conducted. Bulking
is performed at the final staging area using the following
procedures:
• Inspect each tank trailer and remove any residual
materials from the trailer prior to transferring any
bulked materials. This will prevent reactions between
incompatible chemicals.
• To move hazardous liquids, use pumps that are
properly rated (see National Fire Protection Associa-
tion [NFPA] 70 Articles 500-503 and NFPA 497M)
and that have a safety relief valve with a splash
shield. Make sure the pump hoses, casings, finings,
and gaskets are compatible with the material being
pumped.
• Inspect hose lines before beginning work to ensure
that all lines, finings, and valves are intact with no
weak spots.
• Take special precautions when handling hoses as
they often contain residual material that can splash
or spill on the personnel operating the hoses. Protect
personnel against accidental splashing. Protect lines
from vehicular and pedestrian traffic.
• Store flammable liquids in approved containers.
Shipment
Shipment of materials to offsite treatment, storage, or
dispospl facilities involves the entry of waste hauling
vehicles into the site U.S. Department of Transportation
(DOT) regulations (49 CFR Parts 171-178) and EPA regula-
tions (40 CFR Part 263) for shipment of hazardous
-------
11-10
Handling Drums and Other Containers
SITE EXIT
r
O O
o o
00
o o
O 0
o o
o o
o o
oo
oo
00
00
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oo
00
00
o o
o o
o o
o o
o o
o o
o o
o o
SECOND STAGING |
AREA
FINAL STAGING
(BULKING)
\
\
O
\
DRUM OPENING
AND SAMPLING
AREA
/
X
1
og°o°o °
0°oO
OOOOO OOOOOO
ooooo oooooo
1
OOOOOOOO
OOOOOOOO
OOOO OOO
OOOO OOO
OOOO
OOOO
1 ORIGINAL DRUM SITE
OOOOOOOOOOOOO
OOOOOOOOOOOOO
I FIRST STAGING AREA '
Figure 11-5. Possible Staging Areas at a Hazardous Waste Site.
-------
Handling Drums and Other Containers
11-11
00
00
OO
OO
tt OO
2 oo
| 00
< 00
ROADWAY
00
00
OO
OO
til OO
tt °°
3-00
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ROADWAY
00
00
00
00
it! OO
« OO
3 OO
* 00
Figure 11-6. Sample Drum Staging Layout.
Source: Reference [1].
Single-stacked overpack drums awaiting transport off
site. Worker suited in Level C personal protective equip-
ment will spread a tarp over the drums to protect them
during transport.
wastes must be complied with. The following guidelines
can enhance the safety of these operations:
• Locate the final staging (bulking) area as close as
possible to the site exit.
• Prepare a circulation plan that minimizes conflict
between cleanup teams and waste haulers. Install
traffic signs, lights, and other control devices as
necessary.
• Provide adequate area for onsite and hauling vehicles
to turn around. Where necessary, build or improve
onsite roads.
• Stage hauling vehicles in a safe area until ready for
loading with drivers remaining in cab. Minimize the
time that drivers spend in hazardous areas.
• Outfit the driver with appropriate protective
equipment.
• If drums are shipped, tightly seal the drums prior to
loading. Overpack leaking or deteriorated drums prior
to shipment. (Under most circumstances, overpack
drums used for hazardous wastes may not be reused
[49 CFR Part 173.3lc)]). Make sure that truck bed
and walls are clean and smooth to prevent damage to
drums. Do not double stack drums. Secure drums to
prevent shifting during transport.
• Keep bulk solids several inches below the top of the
truck container. Cover loads with a layer of clean soil,
foam, and/or tarp. Secure the load to prevent shifting
or release during transport.
• Weigh vehicles periodically to ensure that vehicle and
road weight limits are not exceeded.
• Decontaminate vehicle tires prior to leaving the site
to ensure that contamination is not carried onto pub-
lic roads.
• Check periodically to ensure that vehicles are not
releasing dust or vapor emissions off site.
• Develop procedures for responding quickly to offsite
vehicle breakdown and accidents to ensure minimal
public impact.
Special Case Problems
Tanks and Vaults
For tanks and vaults, which are often found on hazardous
waste sites, the following procedures are recommended:
• In general, when opening a tank or vault follow the
same procedures as for a sealed drum. If necessary,
vent excess pressure if volatile substances are
stored. Place deflecting shields between workers and
the opening to prevent direct contamination of work-
ers by materials forced out by pressure when the
tank is opened.
• Guard manholes or access portals to prevent person-
nel from falling into the tank.
• Identify the contents through sampling and analysis.
If characterization indicates that the contents can be
safely moved with the available equipment, vacuum
them into a trailer for transportation to a disposal or
recycling facility.
• Empty and decontaminate the tank or vault before
disposal.
• If it is necessary to enter a tank or vault (\&. confined
spaces) for any reason (e.g., to clean off solid
materials or sludges on the bottom or sides of the
tank or vault), the following precautions should be
taken (4):
Ventilate thoroughly prior to entry.
Disconnect connecting pipelines.
Prior to entry, take air samples to prove the
absence of flammable or other hazardous vapors
and to demonstrate that adequate levels of oxygen
exist.
-------
11-12
Handling Drums and Other Containers
Equip the entry team with appropriate respiratory
protection, protective clothing, safety harnesses,
and ropes.
Equip a safety observer with appropriate respira-
tory protection, protective clothing, a safety har-
ness, and ropa
Establish lifeline signals prior to entry so that the
worker and safety observer can communicate by
tugs on the ropa
Have an additional person available in the immedi-
ate vicinity to assist the safety observer if needed.
Instruct the safety observer not to enter the space
until additional personnel are on scene
Vacuum Thicks
• Wear appropriate protective clothing and equipment
when opening the hatch.
• If possible, use mobile steps or suitable scaffolding
consistent with 29 CFR Part 1910, Subpart D. Avoid
climbing up the ladder and walking across the tank
catwalk.
• If the truck must be climbed, raise and lower equip-
ment and samples in carriers to enable workers to
use two hands while climbing.
• If possible, sample from the top of the vehicla If it is
necessary to sample from the drain spigot, take steps
to prevent spraying of excessive substances. Have all
personnel stand off to the sida Have sorbent
materials on hand in the event of a spill.
• Wherever possible, stay on shora Avoid going out
over the water.
• Be aware that some solid wastes may float and give
the appearance of solid cracked mud. Caution should
be exercised when working along shorelines.
References
1. Mayhew, Joe J.; G.M. Sodear; and D.W. Carroll. 1982.
A Hazardous Waste Site Management Plan. Chemical
Manufacturers Association, Inc., Washington DC.
2. deVera, E.R.; B.P. Simmons; R.O. Stephens; and D.L
Storm. 1980. Samplers and Sampling Procedures for
Hazardous Waste Streams. EPA-600/2-80-018. U.S.
Environmental Protection Agency, Cincinnati, OH.
3. U.S. EPA. 1984. Characterization of Hazardous Waste
Sites—A Methods Manual: Volume II. Available
Sampling Methods. Second edition. EPA 600/
4-84-076.
4. NIOSH. 1979. Criteria for a Recommended Standard:
Working in Confined Spaces. NIOSH No. 80-106. Also
available from U.S. Government Printing Office
(#017-033-00353-0) and National Technical Informa-
tion Service (PB-80-183015).
Elevated Tanks
In general, observe the safety precautions described for
vacuum trucks. In addition:
• Use a safety line and harness.
• Maintain ladders and railings in accordance with
OSHA requirements (29 CFR Part 1910, Subpart D).
Comprassad Gas Cylinder*
• Obtain expert assistance in moving and disposing of
compressed gas cylinders.
• Handle compressed gas cylinders with extreme cau-
tion. The rupture of a cylinder may result in an explo-
sion, and the cylinder may become a dangerous
projectila
• Record the identification numbers on the cylinders to
aid in characterizing their contents.
Ponds and Lagoons
• Drowning is a very real danger for personnel suited in
protective equipment because the weight of protec-
tive equipment increases an individual's overall den-
sity and severely impairs their swimming ability.
Where there is danger of drowning, provide neces-
sary safety gear such as lifeboats, tag lines, railings,
nets, safety harnesses, and flotation gear.
-------
United States
Environmental Protection
Agency
Office of Emergency and
Remedial Response
Washington, DC 20460
Office of
Research and Development
Cincinnati, OH 45268
Superfund
EPA/540/S-92/008
October 1992
Engineering Bulletin
Slurry Walls
Purpose
Section 121(b) of the Comprehensive Environmental Re-
sponse, Compensation, and Liability Act (CERCLA) mandates
the Environmental Protection Agency (EPA) to select remedies
that "utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the maxi-
mum extent practicable" and to prefer remedial actions in
which treatment "permanently and significantly reduces the
volume, toxicity, or mobility of hazardous substances, pollut-
ants, and contaminants as a principal element." The Engineer-
ing Bulletins are a series of documents that summarize the latest
information available on selected treatment and site remediation
technologies and related issues. They provide summaries of
and references for the latest information to help remedial project
managers, on-scene coordinators, contractors, and other site
cleanup managers understand the type of data and site
characteristics needed to evaluate a technology for potential
applicability to their Superfund or other hazardous waste site.
Those documents that describe individual treatment technolo-
gies focus on remedial investigation scoping needs. Addenda
will be issued periodically to update the original bulletins.
Abstract
Slurry walls are used at Superfund sites to contain the
waste or contamination and to reduce the potential of future
migration of waste constituents. In many cases slurry walls are
used in conjunction with other waste treatment technologies,
such as covers and ground water pump-and-treat systems.
The use of this well-established technology is a site-specific
determination. Geophysical investigations and other engineer-
ing studies need to be performed to identify the appropriate
measure or combination of measures (e.g., landfill cover and
slurry wall) to be implemented and the necessary materials of
construction based on the site conditions and constituents of
concern at the site. Site-specific compatibility studies may be
necessary to document the applicability and performance of
the slurry wall technology. The EPA contact whose name is
listed at the end of this bulletin can assist in the location of
other contacts and sources of information necessary for such
studies.
This bulletin discusses various aspects of slurry walls includ-
ing their applicability, limitations on their use, a description of
the technology including innovative techniques, and materials
of construction including new alternative barrier materials, site
requirements, performance data, the status of these methods,
and sources of further information.
Technology Applicability
Slurry walls are applicable at Superfund sites where re-
sidual contamination or wastes must be isolated at the source
in order to reduce possible harm to the public and environment
by minimizing the migration of waste constituents present
These subusurface barriers are designed to serve a number of
functions, including isolating wastes from the environment
thereby containing the leachate and contaminated ground
water, and possibly returning the site to future land use.
Slurry walls are often used where a waste mass is too large
for practical treatment, where residuals from the treatment are
landfilled, and where soluble and mobile constituents pose an
imminent threat to a source of drinking water. Slurry walls can
generally be implemented quickly, and the construction re-
quirements and practices associated with their installation are
well understood.
The design of slurry walls is site specific and depends on
the intended function(s) of the system. A variety of natural,
synthetic, and composite materials and construction techniques
are available for consideration when they are selected for use at
a Superfund site.
Slurry walls can be used in a number of ways to contain
wastes or contamination in the subsurface environment, thereby
minimizing the potential for further contamination. Typical
slurry wall construction involves soil-bentonite (SB) or cement-
bentonite (CB) mixtures. These structures are often used in
conjunction with covers and treatment technologies such as in
situ treatment and ground water collection and treatment
systems. Source containment can be achieved through a num-
ber of mechanisms including diverting ground water flow,
capturing contaminated ground water, or creating an upward
ground water gradient within the area of confinement (e.g., in
conjunction with a ground water pump-and-treat system).
Containment may also be achieved by lowering the groundwa-
ter level inside the containment area. This will help to reduce
hydraulically driven transport (known as "advective transport")
from the containment area. However, even if the hydraulic
-------
gradient is directed towards the containment area, transport of
the contaminants (although thought to be minimal) is still
possible. In many cases slurry walls are expected to be in
contact with contaminants, therefore, chemical compatibility
of the barrier materials and the contaminants may be an issue
[1, p. 373-374].
The effectiveness of slurry walls and high density polyethyl-
ene (HOPE) gee-membranes on soils and ground water con-
taminated with general contaminant groups is shown in Table
1. Examples of constituents within contaminant groups are
provided in the 'Technology Screening Guide for Treatment of
CERCLA Soils and Sludges" [2]. This table is based on current
available information or on professional judgment where no
information was available. The proven effectiveness of the
technology for a particular site or waste does not ensure that it
will be effective at all sites or that the containment efficiencies
achieved will be acceptable at other sites. For ratings used in
this table, demonstrated effectiveness means that, at some
scale, compatibility tests showed that the technology was effec-
tive or compatible with that particular contaminant and matrix.
Table 1
Effectiveness of HOPE Geomembranes and Slurry Walls
on General Contaminant Groups for Soil and
Groundwoter
Contaminant Croups
Effectiveness
HOPE Slum Walls
Ceomembranes SB CB
Halogenated volatile*
Halogenated semivolatiles
Nonhalogenated volatile:
Nonhalogenated semivolatiles
PCBs
Pesticides (halogenated)
Dioxins/Furans
Organic cyanides
Organic corrosives
Volatile metals
Nonvolatile metals
Asbestos
Radioactive materials
Inorganic corrosives
Inorganic cyanides
V T
V T
o o
T
V
T
V
O
T
O
T
Oxidizen
Reducers
O
T
a
T
• Demonstrated Effectiveness: Short-term effectiveness demonstrated
at some scale.
T Potential Effectiveness: Expert opinion that technology will work.
Q No Expected Effectiveness: Expert opinion that technology will
not wont.
The ratings of potential effectiveness and no expected effective-
ness are both based on expert judgment. Where potential
effectiveness is indicated, the technology is believed capable of
successfully containing the contaminant groups in a particular
matrix. When the technology is not applicable or will probably
not work for a particular combination of contaminant group
and matrix, a no-expected-effectiveness rating is given.
Limitations
In the construction of most slurry walls it is important that
the barrier is extended and property sealed into a confining
layer (aquitard) so that seepage under the wall does not occur.
For a light, non-aqueous phase liquid a hanging slurry may be
used. Similarly, irregularities in the wall itself (e.g., soil slumps)
may also cause increased hydraulic conductivity.
Slurry walls also are susceptible to chemical attack if the
proper backfill mixture is not used. Compatibility of slurry wall
materials and contaminants should be assessed in the project
design phase.
Slurry walls also may be affected greatly by wet/dry cycles
which may occur. The cycles could cause excessive desiccation
which can significantly increase the porosity of the wall.
Once the slurry walls are completed, it is often difficult to
assess their actual performance. Therefore, long-term ground
water monitoring programs are needed at these sites to ensure
that migration of waste constituents does not occur.
Technology Description
Low-permeability slurry walls serve several purposes includ-
ing redirecting ground water flow, containing contaminated
materials and contaminated ground water, and providing in-
creased subsurface structural integrity. The use of vertical barri-
ers in the construction business for dewatering excavations and
building foundations is well established.
The construction of slurry walls involves the excavation of a
vertical trench using a bentonite-water slurry to hydraulically
shore up the trench during construction and seal the pones in
the trench walls via formation of a "filter cake" [3, p. 2-17].
Slurry walls are generally 20 to 80 feet deep with widths 2 to 3
feet These dimensions may vary from site to site. There are
specially designed "long stick" backhoes that dig to 90 foot
depths. Generally, there will be a substantial cost increase for
walls deeper than 90 feet Clam shell excavators can reach
depths of more than 150 feet. Slurry walls constructed at water
dam projects have extended to 400 feet using specialized mill-
ing cutters. Depending on the site conditions and contami-
nants, the trench can be either excavated to a level below the
water table to capture chemical "floaters" (this is termed a
"hanging wall") or extended ("keyed") into a lower confining
layer (aquitard) [3, p. 3-1]. Similarly, on the horizontal plane
the slurry wall can be constructed around the entire perimeter
of the waste material/site or portions thereof (e.g., upgradient,
* [reference number, page number]
Engineering Bulletin: Slurry Walls
-------
Figure 1
Aerial and Cross-section View Showing Implementation of Slurry Walls (4)
Groundwater Flow
Slurry Wall
• Groundwater Monitoring Well
O Groundwater Extraction Well
LANDFILL COVER g
BEDROCK OR AOUITARD
downgradient). Figure 1 diagrams a waste area encircled by a
slurry wall with extraction and monitoring wells inside and
outside of the waste area, respectively along with a cross-
section view of a slurry wall being used with the landfill cover
technology [4, p. 1].
The principal distinctions among slurry walls are differ-
ences in the low-permeability materials used to fill the trenches.
The ultimate permeability of the wall is controlled by water
content and ratios of bentonite/soil or bentonite/cement. In
the case of a SB wall, the excavated soil is mixed with bentonite
outside of the trench and used to backfill the trench. During the
construction of a CB slurry wall, the CB mixture serves as both
the initial slurry and the trench backfill. When this backfill gels
(SB) or sets (CB), the result is a continuous barrier with lower
permeability than the surrounding soils. A landfill cover, if
Engineering Bulletin: Slurry Walls
-------
Figure 2
Schematic Diagram of Typical Slurry Wall and Bio-polymer Slurry Trench (9)*
1 Drawing not to scale
KEY
employed, must extend over the finished slurry wall to com-
plete the containment and to avoid desiccation.
Soil-bentonite slurry walls are the most popular since they
have a lower permeability than CB walls, and are less costly [3,
p. 1-6] [5, p. 2]. Attapulgite may also be used in situations
where the bentonite is not compatible with the waste [5, p.16].
A newer development is the use of fly ash as a high carbon
additive not only to lower the permeability of the SB but also to
increase the adsorption capacity of the SB with respect to the
transport of organic chemicals [6, p. 1 ][7, p. 444]. Permeabilities
of SB walls as low as 5.0 x. 1O9 cm/sec have been reported
although permeabilities around 1 x 10"7 cm/sec are more typi-
cal [3, p. 2-28]. The primary advantage of the CB wall is its
greater shear strength and lower compressibility. CB walls are
often used on unstable slopes and steep terrain or where soils of
low permeability are not accessible [3, p. 2-40]. The lowest
permeabilities of CB walls are typically 1 x lO"6 cm/sec or
greater [3, p. 2-42] [5, p. 14]. It should be noted that organic
and inorganic contaminants in ground water/leachate can have
a detrimental effect on bentonite and the trench backfill mate-
rial in both SB and CB walls. Therefore, it is imperative that a
compatibility testing program be conducted in order to deter-
mine the appropriate backfill mixture.
Composite slurry walls incorporate an additional barrier,
such as a geomembrane, within the trench to improve imper-
meability and chemical resistance. The geomembranes often
are plastic screens that are comprised of HDPE pile plank sec-
tions which lock together. The locking mechanism is designed
to minimize the leakage of the contaminated ground water.
Table 2 shows one vendor's experience in using HDPE as a
geomembrane [8]. The membrane: is easy to install; has a long
life; and is resistant to animal and vegetation intrusion, microor-
ganisms, and decay. Combining the membrane with a bento-
nite slurry wall may be the most effective combination. It is
usually effective to construct the bentonite-cement slurry wall
and then install the membrane in the middle of the wall. The
toe of the membrane sheet is stabilized in the backfill material,
cement, or in a special grout [5, p.4]. The installation is
reported to be effective in most every type of soil, is watertight
and may be constructed to greater depths.
A relatively new development in the construction of slurry
walls is the use of mixed-in-place walls (also referred to as soil-
mixed walls). The process was originally developed in Japan. A
drill rig with multi-shaft augers and mixing paddles is used to
drill into the soil. During the drilling operation a fluid slurry or
grout is injected and mixed with the soil to form a column. In
constructing a mixed-in-place wall the columns are overlapped
to form a continuous barrier. This method of vertical barrier
construction is recommended for sites where contaminated
soils will be encountered, soils are soft, traditional trenches
might fail due to hydraulic forces, or space availability for
construction equipment is limited. Both this method and a
modified method termed "dry jet mixing" are usually more
expensive than traditional slurry walls [5, p. 7] [9].
Another application of traditional slurry wall construction
techniques is the construction of permeable trenches called
bio-polymer slurry drainage trenches [10] [11]. Figure 2 dia-
grams a slurry wall and a bio-polymer slurry drainage trench
constructed around a waste source; this will typically involve
the use of a landfill cover in conjunction with the wall. Rather
than restricting ground water flow, these trenches are con-
structed as interceptor drains or extraction trenches for collect-
ing or removing leachate, ground water, and ground water-
borne contaminants. These trenches also can be used as
recharge systems. The construction sequence is the same as
the traditional method described above. However, a biode-
gradable material (i.e., bio-polymer) with a high gel strength is
used in the place of bentonite in the slurry, and the trench is
backfilled with permeable materials such as sand or gravel.
Once the trench is completed, the bio-polymer either degrades
Engineering Bulletin: Slurry Walls
-------
or is broken with a breaker solution that is applied to the
trench. Once the bio-polymer filter cake is broken the sur-
rounding soil formation returns to its original hydraulic con-
ductivity. Groundwater collected in the trench can be re-
moved by use of an extraction well or other collection system
installed in the trench [10]. A bio-polymer trench can be used
in conjunction with an SB or CB slurry wall to collect leachate or
a contaminated plume within the wall (similar to the function
of a well-point collection system). A geomembrane also can be
installed with the bio-polymer wall to restrict ground water
flow beyond the bio-polymer wall.
Grouting, including jet grouting, employs high pressure
injection of a low-permeability substance into fractured or
unconsolidated geologic material. This technology can be
used to seal fractures in otherwise impermeable layers or con-
struct vertical barriers in soil through the injection of grout into
holes drilled at closely spaced intervals (i.e., grout curtain) [5,
p.8] [12, p. 5-97]. A number of substances can be used as
grout including cement, alkali silicates, and organic polymers
[12, p. 5-97 - 5-101 ]. However, concerns surround the use of
grouting for the construction of vertical barriers in soils because
it is difficult to achieve and verify complete permeation of the
soil by the grout Therefore, the desired low permeabilities
may not be achieved as expected [5, p.8] [13, p. 7].
Site Requirements
Treatment of contaminated soils or other waste materials
requires that a site safety plan be developed to provide for
personnel protection and special handling measures.
The construction of slurry walls requires a variety of con-
struction equipment for excavation, earth moving, mixing, and
pumping. Knowledge of the site, local soil, and hydrogeologic
conditions is necessary. The identification of underground
utilities is especially important during the construction phase [8].
In slurry wall construction, large backhoes, clamshell exca-
vators, or multi-shaft drill rigs are used to excavate the trenches.
Dozers or graders are used for mixing and placement of back-
fill. Preparation of the slurry requires batch mixers, hydration
ponds, pumps, and hoses. An adequate supply of water and
storage tanks is needed as well as electricity for the operation of
mixers, pumps, and lighting. Areas adjacent to the trench
need to be available for the storage of trench spoils (which
could potentially be contaminated) and the mixing of backfill.
If excavated soils will not be acceptable for use in the slurry wall
backfill suitable backfill material must be imported from off the
site. In the case of CB walls, plans must be made for the
disposal of the spoils since they are not backfilled. In marked
contrast, deep soil mixing techniques require less surface storage
area, use less heavy equipment, and may produce a smaller volume
of trench spoils.
Performance Data
Performance data presented in this bulletin should not be
considered directly applicable to all sites. A number of variables
such as geographic region, topography, and material availabil-
ity can affect the walls performance. A thorough characteriza-
tion of the site and a compatability study is highly recom-
mended.
At the Hill Air Force Base in northern Utah the installation
of a slurry wall, landfill covers, groundwater extraction and
treatment, and monitoring was implemented to respond to
ground water and soil contamination at the site. The slurry
wall was installed along the upgradient boundary on three
sides of Operable Unit No. 1 to intercept and divert ground
water away from the disposal site. Operable Unit No. 1 consists
of Landfill No. 3, Landfill No. 4, Chem Pits No. 1 and 2, and Fire
Training Area No. 1. Shallow perched groundwater and soils
present were contaminated with halogenated organics and
heavy metals. The performance of the slurry wall had been
questioned because it was not successfully keyed into the
underlying clay layer. This oversight was attributed to both the
inadequate number and depth of soil borings. The combina-
tion of landfill caps, slurry wall, and ground water extraction
and treatment has resulted in a significant reduction in the
concentrations of organics and inorganics detected seeping at
the toe of Landfill No. 4. Organics were reduced to levels below
5 percent of their pre-remedial action levels and iron was
reduced to 20 percent of its original observed concentration.
Three seperate QA/QC projects were implemented to assess the in
situ effectiveness of the slurry wall. The determination of ground
water levels in monitoring wells on the inside and outside of the
wall provided the most the useful data [14].
Table 2
Relative Chemical Resistivity of an HOPE
Geomembrane (6)°
Aromatic Compounds
Benzene +
Ethylene Benzene ++
Toluene +
Xylene ++
Phenol -t-f
Polvcyelic Hydrocarbons
Naphthalene ++
Anthracene -t-t-
Phenanthrene «•+
Pyrene •»••»•
Benzopyrene ++
Chlorinated Hydrocarbons
Chlorobenzenej
Chlorophenols
PCBs
Inorganic Contamination
NH4 -n-
Fluorine ++
CN ++
Sulphides ++
PO. -n-
Other Sources of Contamination
Tetrahydrofurane +
Pyrides ++
Tetrahydrothiophene ++
Cyclohexanone ++
Styrene +•»•
Petrol •»••»•
Mineral Oil ++
Pesticides
Organic Chlorine
Compounds
Pesticides
Key: ++ Good Resistance
+ Average Resistance
Adapted from vendor's marketing brochure
Engineering Bulletin: Slurry Walls
-------
At the Upari Landfill Superfund Site in New jersey, a SB
slurry wall was installed to encircle the landfill. A landfill cover,
incorporating a 40 mil HOPE geomembrane, also was installed
at the site. Heavy rains and snowmelt prior to the complete cap
installation resulted in the need to perform an emergency
removal (i.e., dewatering). Several years after completion of
the slurry wall and landfill cover their effectiveness was evalu-
ated during a subsequent feasibility study. The study con-
cluded that the goal of an effective permeability of 1 x 10*7 cm/
sec had been achieved in the slurry wall. Monitoring wells will
be located at least 5 feet from the slurry wall on the upgradient
side and 7 feet on the down gradient side [15]. The combina-
tion of technologies being used along with the slurry wall
appears to be effectively containing the waste and its constitu-
ents.
A SB slurry wall, up to 70 feet deep, was installed at a
municipal landfill Superfund site in Gratiot County, Michigan.
The slurry wall was needed to prevent leachate from migrating
into the local ground water. Approximately 250,000 ft.2 of SB
slurry wall was installed at the site. The confirmation of achiev-
ing a goal of a laboratory permeability of less than 1 x 10~7 cm/
sec for the soil-bentonite backfill was reported by an indepen-
dent laboratory [16].
A SB slurry wall, extending through three aquifers, was
installed at the Raytheon NPL site in Mountain View, California.
Soil and ground water at the site were contaminated with
industrial solvents. Permeability tests performed on the back-
filled material achieved the goal of 1 x 10"7 cm/sec or less.
Associated activities at the site included the rerouting of under-
ground utilities, construction of 3-foot-high earthen berms
around all work areas, construction of two bentonite slurry
storage ponds ,and construction of three lined ponds capable
of storing 300,000 gallons of storm water. A ground water
extraction and stripping/filtration system is also in place at the
site. The slurry wall, purposely, was not keyed into an aquitard
so that the ground water extraction program would create an
upward gradient, thus serving to further contain the contami-
nants. The system appears to be functioning properly with the
implementation of the combination of the technologies [17]
[18]. However, this is the exception rather than the rule.
Technology Status
The construction and installation of slurry walls is consid-
ered a well-established technology. Several firms have experi-
ence in constructing this technology. Similarly, there are several
vendors of geosynthetic materials, bentonitic materials, and
proprietary additives for use in these barriers.
In EPA's FY 1989 ROD Annual Report [19] 26 ROOs speci-
fied slurry walls as part of the remedial action. Of the ROOs
specifying slurry walls, 22 also indicated that covers would be
used. Table 3 presents the status of selected superfund sites
employing slurry walls.
While site-specific geophysical and engineering studies (e.g.,
compatibility testing of ground water and backfill materials) are
needed to determine the appropriate materials and construc-
tion specifications, this technology can effectively isolate wastes
and contain migration of hazardous constituents. Slurry walls
also may be implemented rather quickly in conjunction with
other remedial actions. Long-term monitoring is needed to
evaluate the effectiveness of the slurry wall.
EPA Contact
Technology-specific questions regarding slurry walls may
be directed to:
Mr. Eugene Harris
U.S. Environmental Protection Agency
Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Cincinnati, Ohio 45268
(513)569-7862
Acknowledgements
This bulletin was prepared for the U.S. Environmental Pro-
tection Agency, Office of Research and Development (ORD),
Risk Reduction Engineering Laboratory (RREL), Cincinnati, Ohio,
by Science Applications International Corporation (SAIQ under
contract No. 68-C8-0062. Mr. Eugene Harris served as the EPA
Technical Project Monitor. Mr. Gary Baker was SAIC's Work
Assignment Manager. This bulletin was written by Mr. Cecil
Cross of SAIC. The author is especially grateful to Mr. Eric Saylor
of SAIC who contributed significantly during the development
of the document
The following contractor personnel have contributed
their time and comments by participating in the expert review
meetings and/or peer reviewing the document:
Dr. David Daniel
Dr. Charles Shackelford
Ms. Mary Boyer
University of Texas
Colorado State University
SAIC
Engineering Bulletin: Slurry Walls
-------
Tabled
Selected Superfund Sites Employing Slurry Walls (19)
SITE
Ninth Avenue Dump
Outboard Marine
Liquid Disposal
Industrial Waste Control
E.H. Shilling Landfill
Allied/lronton Coke
Florence Landfill
South Brunswick
Sylvester
Waste Disposal Engineering
Diamond Alkali
Hooker- 102nd St.
Scientific Chemical Processing
Location (Region)
Gary, IN (5)
Waukegan, IL (5)
Utica, Ml (5)
Fort Smith, AR (6)
Ironton, OH (5)
Ironton, OH (5)
Florence Township, NJ (2)
New Brunswick, N) (2)
Nashua, NH(1)
Andover, MN (5)
Neward, NJ (2)
Niagra Falls, NY (2)
Carlstadt, NJ (2)
Status
In design phase
In operation
In design phase
In operation since 3/91
In design phase
In pre-design phase
Design completed; remedial action
beginning soon
In operation since 1 985
In operation since 1 983
In design phase
In pre-design phase
In remedial design phase
Completed 1992
REFERENCES
1. Gray, Donald H. and Weber, Walter). Diffusional
Transport of Hazardous Waste Leachate Across Clay
Barriers. Seventh Annual Madison Waste Conference,
Sept. 11-12,1984.
2. Technology Screening Guide for Treatment of CERCLA
Soils and Sludges. EPA/540/2-88/004. U.S. Environmen-
tal Protection Agency. 1988.
3. Slurry Trench Construction for Pollution Migration
Control. EPA-540/2-84-001. U.S. Environmental
Protection Agency. February 1984.
4. Waste Containment: Soil-Bentonite Slurry Walls. NEESA
Document No. 20.2-051.1, November 1991.
5. Ryan, C.R. Vertical Barriers in Soil for Pollution Contain-
ment. Presented at the ASCE-GT Specialty Conference-
Ceotechnical Practice for Waste Disposal. Ann Arbor,
Michigan. June 15-17,1987.
6. Bergstrom, Wayne R., Gray, Donald H. Fly Ash Utilization
in Soil-Bentonite Slurry Trench Sutoff Walls. Presented at
the Twelfth Annual Madison Waste Conference, Sept. 20-
21,1989.
7. Gray, D.H., Bergstrom, W.R., Mott, H.V., and Weber, W.J.
Fly Ash Utilization in Cuttoff Wall Backfill Mixes. Proceed-
ings from the Ninth Annual Symposium, Orlando, Fl_
January 1991.
8. Gundle Lining Systems, Inc. Geolock Vertical Watertight
Plastic Screen for Isolating Ground Contamination.
Marketing Brochure. 1991.
9. Geo-Con, Inc. Deep Soil Mixing, Case Study No. 1.
Marketing Brochure. 1989.
10. Geo-Con, Inc. Deep Draining Trench By the Bio-Polymer
Slurry Trench Method, Technical Brief. Marketing
Brochure. 1991.
11. Hanford, R.W. and S.W. Day. Installation of a Deep
Drainage Trench by the Bio-Polymer Slurry Drain
Technique.-Presented at the NWWA Outdoor Action
Conference, Las Vegas, Nevada. May 1988.
12. Handbook - Remedial Action at Waste Disposal Sites
(Revised). EPA-625/6-85/066. U.S. Environmental
Protection Agency. 1985.
Engineering Bulletin: Slurry Walls
•OS. QtH»nmm PrtnOng OMett 1882 — M8-080tt0082
-------
13. Technological Approaches to the Cleanup of Radiologi-
cally Contaminated Superfund Sites. EPA/540/2-88/002.
U.S. Environmental Protection Agency. August 1988.
14. Dalpais, E.A., E. Heyse, and W.R. James. Overview of
Contaminated Sites at Hill Air Force Base, Utah, and Case
History of Actions Taken at Landfills No. 3 and 4, Chem.
Pits land 2. Utah Geol. Assoc. Publication 17. 1989.
15. U.S. Environmental Protection Agency. On-site FS for
Lipari Landfill, Final Draft Report. Prepared for U.S. EPA by
COM, Inc. et al. August 1985.
16. Geo-Con, Inc. Slurry Walls, Case Study No. 3, Marketing
Brochure. 1990.
17. CKN Hayward Baker, Inc. Case Study Slurry Trench Cut-
off wall, Raytheon Company, Mountain View, CA.
Marketing Brochure. 1988.
18. Burke, G.K. and F.N. Achhomer, Construction and Qualit
Assessment of the In Situ Containment of Contaminated
Groundwater. In Proceedings of the 5th National
Conference on Hazardous Wastes and Hazardous
Materials. April 1988.
19. ROD Annual Report: FY 90. EPA/540/8-91/067. U.S.
Environmental Protection Agency. July 1991.
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PA
EPA
PERMIT No. G-35
EPA/540/S-92/008
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Section 5
-------
TECHNOLOGY SCREENING
STUDENT PERFORMANCE OBJECTIVES
At the conclusion of this unit, students will be able to:
1. Define treatability study
2. State one goal of a treatability study
3. State one purpose of a pre-ROD treatability study
4. State one purpose of a post-ROD treatability study
5. List the three tiers designated by EPA for a treatability study
6. State one characteristic of each of the three tiers of a
treatability study
7. State one purpose for prescreening and scoping for a
treatability study
8. Identify one group that routinely performs treatability studies
and tests
9. Define the "Treatability Study Samples Exclusion Rule"
10. State three different sources of treatability information.
NOTE: Unless otherwise stated, the conditions for
performance are using all references and materials
provided in the course, and the standards of
performance are without error.
7/95
-------
NOTES
TECHNOLOGY
SCREENING
S-1
TREATABILITY STUDY
Study where hazardous waste is subjected
to a treatment process to determine:
• Amenability to treatment process
• Pretreatment requirements
• Optimal process conditions
40 CFR Part 2S0.10
S-2
TREATABILITY STUDY (cont.)
Study where hazardous waste is subjected
to a treatment process to determine:
• Efficiency of treatment process
• Residual characteristics and volume
40 CFR Part 280L10
3-3
-U
7/95
Technology Screening
-------
WHY CONDUCT A TREATABILITY
STUDY
Mandated by CERCLA 121(b)
Reduce volume, toxicity, or mobility
Use permanent solutions and alternatives
to maximum extent practicable
Evaluate technologies for record of
decision (ROD)
S-4
TREATABILITY STUDY GOALS
Aid in remedy selection
Aid in remedy implementation
S-5
NOTES
Technology Screening 2 7/95
-------
The Role of Treatability Studies in the RI/FS Process
Scoping
— the
Technology
Prescreening
and
Treatability
Study
Scoping
Remedial Investigation/
Feasability Study —
Site
Identification
of Alternatives
Record of
* Decision
•
Remedy
Selection
Characterization
"and Technology
Screening
Evaluation
"of Alternatives
REMEDY SCREENING
TREATABILITY
to determine
potential feasibility
REMEDY SELECTION
TREATABILITY
to develop performance
and cost data
Remedial Design/
Remedial Action -
Implementation
of Remedy
RD/RA TREATABILITY
to develop detailed
design and cost data and
to confirm performance
U.S. EPA 1992
S-6
NOTES
7/95
Technology Screening
-------
NOTES
TREATABILITY STUDY TIMING
Before the ROD is issued (pre-ROD)
After the ROD is issued (post-ROD)
PRE-ROD PURPOSE
8-7
Data for detailed analysis in feasibility
study (FS)
National Contingency Plan (NCR)
evaluation criteria
"- Threshold criteria (required)
[- Primary balancing criteria (remedy
based on)
.- Modifying criteria (ROD)
s-s
• Determine design, cost, and performance
data
• Select multiple vendors and processes
• Implement contingency ROD
• Support design specifications and
treatment trains
S-8
Technology Screening
7/95
-------
NOTES
TIERED APPROACH TO
TREATABILITY STUDIES
• Tier 1
• Tier 2
• Tiers
Remedy Screening
Remedy Selection
Remedial Design and Remedial
Action
S-10
TREATABILITY STUDY FLOWCHART
Prescreening Rl/
Site characterization
Presumptive remedies
^
f
Focused feasibility
study
*~.
i
^— -s>
Evaluate existing
technologies
a
Remedy screening
1
Remedy selection
Record of decision
Remedial Design
Remedial Action
S-11
TECHNOLOGY PRESCREENING
AND SCOPING
• Perform as early as possible
• Conduct literature and database searches
• Consult experts
• Determine data needs/data quality
objectives
S-12
7/95
Technology Screening
-------
NOTES
REMEDY SCREENING
Tierl
Potential feasibility
Performance goals
Additional data needs
S-13
REMEDY SCREENING (cont.)
Tierl
• Laboratory/bench scale
• Small quantities, quick results
• Batch reactions, yes/no answers
• Hours to days
• $10,000 to $50,000
REMEDY SELECTION
Tier 2
• Performance and cost data
• Verify cleanup criteria
S-14
S-15
Technology Screening
7/95
-------
REMEDY SELECTION (cont.)
Tier 2
• Bench/pilot scale
• Batch or continuous processes
• Days to weeks
• $50,000 to $250,000
S-18
DESIGN/REMEDIAL
ACTION - Tier 3
Detailed design
Cost and performance data
S-17
REMEDIAL DESIGN/REMEDIAL
ACTION (cont.) - Tier 3
• Pilot/full scale
• Batch or continuous reactions
• Weeks to months
• $250,000 to $1,000,000
S-18
NOTES
^UP-
7/95
Technology Screening
-------
NOTES
WHO PERFORMS
TREATABILITY STUDIES
• Vendors
• Consultants
• EPA research facilities
• Federal agencies
S-1S
TREATABILITY STUDY SAMPLES
EXCLUSION RULE
RCRA - February 18, 1994, Final Subtitle C
• Quantity
- 10,000 kg nonacute hazardous waste
- 2,500 kg acute hazardous waste
• Time
- Bioremediation (2 years)
S-20
TREATABILITY STUBY AN©
INF®RMATI0N S®URCES
• Training courses and conferences
• Literature
• Electronic information systems
- Bulletin boards
- Databases
3-21
Technology Screening
7/95
-------
REFERENCES
Federal Register. February 18, 1994. Rules and Regulations: Environmental Protection Agency.
40 CFR Part 261. Hazardous Waste Management System: Identification and Listing of Hazardous
Waste; Treatability Studies Exclusion Rule. Volume 59, Number 34, 8362-8366.
U.S. Congress. 1986. Superfund Amendments and Reauthorization Act of 1986. Public Law 99-
499. 99th Congress.
U.S. EPA. 1987. Data Quality Objectives for Remedial Response Activities: Development
Process. EPA-540/G-87/003. OSWER Directive No. 9355.0-7b. U.S. Environmental Protection
Agency, Office of Emergency and Remedial Response and Office of Solid Waste and Emergency
Response, Washington, DC.
U.S. EPA. 1988. Guidance for Conducting Remedial Investigations and Feasibility Studies Under
CERCLA, Interim Final. EPA/540/G-89/004. U.S. Environmental Protection Agency, Office of
Emergency and Remedial Response, Washington, DC.
U.S. EPA. 1988. Technology Screening Guide for Treatment of CERCLA Soils and Sludges.
EPA/540/2-88/004. U.S. Environmental Protection Agency, Office of Emergency and Remedial
Response, Washington, DC.
U.S. EPA. 1990. Engineering Bulletin: Soil Washing Treatment. EPA/540/2-90/017. U.S.
Environmental Protection Agency, Office of Emergency and Remedial Response, Washington, DC,
and Office of Research and Development, Cincinnati, OH.
U.S. EPA. 1990. Technical Support Services for Superfund Site Remediation. EPA-540/8-90/001.
U.S. Environmental Protection Agency, Office of Emergency and Remedial Response and Office of
Solid Waste and Emergency Response, Washington, DC.
U.S. EPA. 1991. Accessing Federal Data Bases for Contaminated Site Clean-up Technologies.
Third edition. EPA-542/B-93/008. U.S. Environmental Protection Agency, Member Agencies of
the Federal Remediation Technologies Roundtable, Washington, DC.
U.S. EPA. 1991. Bibliography of Federal Reports and Publications Describing Alternative and
Innovative Treatment Technologies for Corrective Action and Site Remediation. EPA-540/8-91/007.
U.S. Environmental Protection Agency, Member Agencies of the Federal Remediation Technologies
Roundtable, Washington, DC.
U.S. EPA. 1991. Compendium of Superfund Program Publications. EPA/540/8-91/014. U.S.
Environmental Protection Agency, Office of Emergency and Remedial Response, Washington, DC.
U.S. EPA. 1991. Engineering Bulletin: Air Stripping of Aqueous Solutions, EPA-540/2-91/022.
U.S. Environmental Protection Agency, Risk Reduction Engineering Laboratory, Office of Research
and Development, Cincinnati, OH, and Office of Emergency and Remedial Response, Office of Solid
Waste and Emergency Response, Washington, DC.
7/95 9 Technology Screening
-------
U.S. EPA. 1991. Engineering Bulletin: Chemical Oxidation Treatment. EPA-540/2-91/025. U.S.
Environmental Protection Agency, Risk Reduction Engineering Laboratory, Office of Research and
Development, Cincinnati, OH, and Office of Emergency and Remedial Response, Office of Solid
Waste and Emergency Response, Washington, DC.
U.S. EPA. 1991. Engineering Bulletin - Control of Air Emissions from Materials Handling During
Remediation. EPA-540/2-91/023. U.S. Environmental Protection Agency, Risk Reduction
Engineering Laboratory, Office of Research and Development, Cincinnati, OH, and Office of
Emergency and Remedial Response, Office of Solid Waste and Emergency Response, Washington,
DC.
U.S. EPA. 1991. Engineering Bulletin: In Situ Soil Flushing. EPA-540/2-91/021. U.S.
Environmental Protection Agency, Risk Reduction Engineering Laboratory, Office of Research and
Development, Cincinnati, OH, and Office of Emergency and Remedial Response, Office of Solid
Waste and Emergency Response, Washington, DC.
U.S. EPA. 1991. Engineering Bulletin: In Situ Soil Vapor Extraction Treatment. EPA-540/2-
91/006. U.S. Environmental Protection Agency, Risk Reduction Engineering Laboratory, Office
of Research and Development, Cincinnati, OH, and Office of Emergency and Remedial Response,
Office of Solid Waste and Emergency Response, Washington, DC.
U.S. EPA. 1991. Engineering Bulletin: Thermal Desorption Treatment. EPA-540/2-91/008. U.S.
Environmental Protection Agency, Risk Reduction Engineering Laboratory, Office of Research and
Development, Cincinnati, OH, and Office of Emergency and Remedial Response, Office of Solid
Waste and Emergency Response, Washington, DC.
U.S. EPA. 1991. Guide for Conducting Treatability Studies Under CERCLA: Soil Washing.
Quick Reference Fact Sheet. EPA/540/2-91/020B. U.S. Environmental Protection Agency, Office
of Emergency and Remedial Response, Office of Solid Waste and Emergency Response, Washington,
DC.
U.S. EPA. 1991. Innovative Hazardous Waste Treatment Technologies: A Developer's Guide to
Support Services. EPA/540/2-91/012. U.S. Environmental Protection Agency, Office of Emergency
and Remedial Response, Washington, DC.
U.S. EPA. 1991. Superfund Engineering Issue-Treatment of lead-contaminated soils. EPA-540/2-
91/009. U.S. Environmental Protection Agency, Risk Reduction Engineering Laboratory, Office
of Research and Development, Cincinnati, OH, and Office of Emergency and Remedial Response,
Office of Solid Waste and Emergency Response, Washington, DC.
U.S. EPA. 1992. Contaminants and Remedial Options at Wood Preserving Sites. EPA/600/R-
92/182. U.S. Environmental Protection Agency, Office of Research and Development, Washington,
DC.
U.S. EPA. 1992. Engineering Bulletin: Air Pathway Analysis. EPA-540/S-92/013. U.S.
Environmental Protection Agency, Risk Reduction Engineering Laboratory, Office of Research and
Development, Cincinnati, OH, and Office of Emergency and Remedial Response, Office of Solid
Waste and Emergency Response, Washington, DC.
Technology Screening 10 7/95
-------
U.S. EPA. 1992. Engineering Bulletin: Design Considerations for Ambient Air Monitoring at
Superfund Sites. EPA-540/S-92/012. U.S. Environmental Protection Agency, Risk Reduction
Engineering Laboratory, Office of Research and Development, Cincinnati, OH, and Office of
Emergency and Remedial Response, Office of Solid Waste and Emergency Response, Washington,
DC.
U.S. EPA. 1992. Engineering Bulletin: Pyrolysis Treatment. EPA-540/S-92/010. U.S.
Environmental Protection Agency, Risk Reduction Engineering Laboratory, Office of Research and
Development, Cincinnati, OH, and Office of Emergency and Remedial Response, Office of Solid
Waste and Emergency Response, Washington, DC.
U.S. EPA. 1992. Engineering Bulletin: Rotating Biological Contactors. EPA-540/S-92/010. U.S.
Environmental Protection Agency, Risk Reduction Engineering Laboratory, Office of Research and
Development, Cincinnati, OH, and Office of Emergency and Remedial Response, Office of Solid
Waste and Emergency Response, Washington, DC.
U.S. EPA. 1992. Engineering Bulletin: Selection of Control Technologies for Remediation of Lead
Battery Recycling Sites. EPA-540/S-92/011. U.S. Environmental Protection Agency, Risk
Reduction Engineering Laboratory, Office of Research and Development, Cincinnati, OH, and Office
of Emergency and Remedial Response, Office of Solid Waste and Emergency Response, Washington,
DC.
U.S. EPA. 1992. Engineering Bulletin: Slurry Walls. EPA-540/S-92/006. U.S. Environmental
Protection Agency, Risk Reduction Engineering Laboratory, Office of Research and Development,
Cincinnati, OH, and Office of Emergency and Remedial Response, Office of Solid Waste and
Emergency Response, Washington, DC.
U.S. EPA. 1992. Engineering Bulletin: Supercritical Water Oxidation. EPA-540/S-92/006. U.S.
Environmental Protection Agency, Risk Reduction Engineering Laboratory, Office of Research and
Development, Cincinnati, OH, and Office of Emergency and Remedial Response, Office of Solid
Waste and Emergency Response, Washington, DC.
U.S. EPA. 1992. Engineering Bulletin: Technology Preselection Data Requirements. EPA/540/S-
92/009. U.S. Environmental Protection Agency, Office of Emergency and Remedial Response,
Washington, DC.
U.S. EPA. 1992. Guide for Conducting Treatability Studies Under CERCLA. EPA/540/R-
92/071a. U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response,
Office of Research and Development, Washington, DC.
U.S. EPA. 1992. Guide for Conducting Treatability Studies Under CERCLA: Aerobic
Biodegradation Screening. Interim Guidance. EPA/540/2-91/013a. U.S. Environmental Protection
Agency, Office of Emergency and Remedial Response, Office of Solid Waste and Emergency
Response, Washington, DC.
U.S. EPA. 1992. Guide for Conducting Treatability Studies Under CERCLA: Aerobic
Biodegradation Screening. Quick Reference Fact Sheet. EPA/540/2-9l/013b. U.S. Environmental
7/95 11 Technology Screening
-------
Protection Agency, Office of Emergency and Remedial Response, Office of Solid Waste and
Emergency Response, Washington, DC.
U.S. EPA. 1992. Guide for Conducting Treatability Studies Under CERCLA: Chemical
Dehalogenation. EPA-540/R-92/013a. U.S. Environmental Protection Agency, Office of
Emergency and Remedial Response, Office of Solid Waste and Emergency Response, Washington,
DC.
U.S. EPA. 1992. Guide for Conducting Treatability Studies Under CERCLA: Soil Vapor
Extraction. Interim Guidance. EPA/540/2-9l/019a. U.S. Environmental Protection Agency, Office
of Emergency and Remedial Response, Office of Solid Waste and Emergency Response, Washington,
DC.
U.S. EPA. 1992. Guide for Conducting Treatability Studies Under CERCLA: Soil Vapor
Extraction. Quick Reference Fact Sheet. EPA/540/2-9l/019b. U.S. Environmental Protection
Agency, Office of Emergency and Remedial Response, Office of Solid Waste and Emergency
Response, Washington, DC.
U.S. EPA. 1992. Guide for Conducting Treatability Studies Under CERCLA: Soil Washing.
Interim Guidance. EPA-540/2-91/020a. U.S. Environmental Protection Agency, Office of
Emergency and Remedial Response, Office of Solid Waste and Emergency Response, Washington,
DC.
U.S. EPA. 1992. Guide for Conducting Treatability Studies Under CERCLA: Solvent Extraction.
Interim Guidance. EPA/540/R-92/016a. U.S. Environmental Protection Agency, Office of
Emergency and Remedial Response, Office of Solid Waste and Emergency Response, Washington,
DC.
U.S. EPA. 1992. Guide for Conducting Treatability Studies Under CERCLA: Solvent Extraction.
Quick Reference Fact Sheet. EPA/540/R-92/016b. U.S. Environmental Protection Agency, Office
of Solid Waste and Emergency Response, Washington, DC.
U.S. EPA. 1992. Guide for Conducting Treatability Studies Under CERCLA: Thermal Desorption
Remedy Selection. Interim Guidance. EPA/540/R-92/074A. U.S. Environmental Protection
Agency, Office of Emergency and Remedial Response, Office of Solid Waste and Emergency
Response, Washington, DC.
U.S. EPA. 1992. Guide for Conducting Treatability Studies Under CERCLA: Thermal
Desorption. Quick Reference Fact Sheet. EPA/540/R-92/074B. U.S. Environmental Protection
Agency, Office of Emergency and Remedial Response, Office of Solid Waste and Emergency
Response, Washington, DC.
U.S. EPA. 1992. Literature Survey of Innovative Technologies for Hazardous Waste Site
Remediation. EPA/542/B-92/004. U.S. Environmental Protection Agency, Office of Emergency
and Remedial Response, Washington, DC.
U.S. EPA. 1992. Superfund Engineering Issue: Considerations for Evaluating the Impact of Metals
Partitioning during the Incineration of Contaminated Soils from Superfund Sites. EPA-540/S-92/014.
Technology Screening 12 7/95
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U.S. Environmental Protection Agency, Risk Reduction Engineering Laboratory, Office of Research
and Development, Cincinnati, OH, and Office of Emergency and Remedial Response, Office of Solid
Waste and Emergency Response, Washington, DC.
U.S. EPA. 1993. Engineering Bulletin - Landfill covers. EPA/540/S-93/500. U.S. Environmental
Protection Agency, Risk Reduction Engineering Laboratory, Office of Research and Development,
Cincinnati, OH, and Office of Emergency and Remedial Response, Office of Solid Waste and
Emergency Response, Washington, DC.
U.S. EPA. 1993. Engineering Forum Issue: Considerations in Deciding to Treat Contaminated
Unsaturated Soils In Situ. EPA/540/S-94/500. U.S. Environmental Protection Agency, Office of
Solid Waste and Emergency Response, Washington, DC.
U.S. EPA. 1993. Federal Publications on Alternative and Innovative Treatment Technologies for
Corrective Action and Site Remediation. Third edition. EPA/542/b-93/007. U.S. Environmental
Protection Agency, Washington, DC.
U.S. EPA. 1993. Guide for Conducting Treatability Studies Under CERCLA: Biodegradation
Remedy Selection. Interim Guidance. EPA/540/R-93/519a. U.S. Environmental Protection
Agency, Office of Solid Waste and Emergency Response, Washington, DC.
U.S. EPA. 1993. Guide for Conducting Treatability Studies Under CERCLA: Biodegradation
Remedy Selection, Quick Reference Fact Sheet. EPA/540/R-93/519b. U.S. Environmental
Protection Agency, Office of Solid Waste and Emergency Response, Washington, DC.
U.S. EPA. 1993. Synopses of Federal Demonstrations of Innovative Site Remediation Techniques.
Third edition. EPA/542/B-93/009. U.S. Environmental Protection Agency, Washington, DC.
U.S. EPA. 1994. Engineering Bulletin - Solvent Extraction. EPA/540/S-94/503. U.S.
Environmental Protection Agency, Office of Emergency and Remedial Response, Washington, DC,
and Office of Research and Development, Cincinnati, OH.
U.S. EPA. 1994. Selecting Innovative Cleanup Technologies: EPA Resources Technology
Innovation Office. U.S. Environmental Protection Agency, Washington, DC.
7/95 13 Technology Screening
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TREATABILITY DATABASES
Database
RREL Treatability Database
ATTIC
COLIS
VISITT
Superfund TSP
Engineering TSC
ERT-TSC
Contact
Glenn Shaul
RREL-ORD
USEPA
(513) 569-7408
Greg Ondich
OEETD
USEPA
(202) 260-5747
Robert Hillger
RREL-ORD
USEPA
(908) 321-6639
VISITT Hotline
(800) 245-4505
Marlene Suit
TIO-OSWER
USEPA
(703) 308-8800
Ben Blaney or Joan Colson
RREL-ORD
(513) 569-7406
Joseph LaFornara
ERB-OERR
USEPA
(908) 321-6740
Technology Screening
14
7/95
-------
xvEPA
United States
Environmental Protection
Agency
Office of Research and
Development
Washington DC 20460
Office of Solid Waste and
Emergency Response
Washington. DC 20460
Superfund
EPA/540/R-92/071 a
October 1992
Guide for Conducting
Treatability Studies under
CERCLA
Final
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EPA/540/R-92/071a
OSWER Directive No. 9380.3-10
November 1992
GUIDE FOR CONDUCTING
TREATABILITY STUDIES UNDER CERCLA
FINAL
Risk Reduction Engineering Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
and
Office of Emergency and Remedial Response
Office of Solid Waste and Emergency Response
U.S. Environmental Protection Agency
Washington, DC 20460
Printed on Recycled Paper
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NOTICE
The information in this document has been funded wholly or in pan by
the U.S. Environmental Protection Agency (EPA) under Contract No.
68-C9-0036. It has been subjected to the Agency's review process and
approved for publication as an EPA document.
The policies and procedures set forth here are intended as guidance to
Agency and other government employees. They do not constitute
rulemaking by the Agency, and may not be relied on to create a
substantive or procedural right enforceable by any other person. The
Government may take action that is at variance with the policies and
procedures in this manual. Mention of trade names or commercial
products does not constitute endorsement or recommendation for use.
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FOREWORD
Today's rapidly developing and changing technologies and industrial
products and practices frequently carry with them the increased gen-
eration of materials that, if improperly dealt with, can threaten both
public health and the environment. The U.S. Environmental Protec-
tion Agency (EPA) is charged by Congress with protecting the Nation's
land, air, and water resources. Under a mandate of national environ-
mental laws, the Agency strives to formulate and implement actions
leading to a compatible balance between human activities and the
ability of natural systems to support and nurture life. These laws direct
the EPA to perform research to define our environmental problems,
measure the impacts, and search for solutions.
The Risk Reduction Engineering Laboratory is responsible for plan-
ning, implementing, and managing research, development, and dem-
onstration programs to provide an authoritative, defensible engineer-
ing basis in support of the policies, programs, and regulations of the
EPA with respect to drinking water, wastewater, pesticides, toxic
substances, solid and hazardous wastes, and Superfund-related activi-
ties. This publication is one of the products of that research and
provides a vital communication link between the researcher and the
user community.
The purpose of this guide is to provide information on conducting
treatability studies. It describes a three-tiered approach that consists of
1) remedy screening, 2) remedy-selection testing, and 3) remedial
design/remedial action testing. It also presents a protocol for conduct-
ing treatability studies in a systematic and stepwise fashion for deter-
mination of the effectiveness of a technology (or combination of
technologies) in remediating a CERCLA site.
ETimothy Oppelt, Director
Risk Reduction Engineering Laboratory
111
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ABSTRACT
Systematically conducted, well-documented treatability studies are an
important component of the removal process, remedial investigation/
feasibility study (RI/FS) process and the remedial design/remedial
action (RD/RA) process under the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA). These stud-
ies provide valuable site-specific data necessary to aid in the screening,
selection, and implementation of the site remedies. This guide focuses
on both treatability studies conducted in support of remedy screening
and selection [i.e., pre-Record of Decision (ROD)] and treatability
studies in support of remedy implementation (i.e., post-ROD).
The guide describes a three-tiered approach for conducting treatability
studies that consists of 1) remedy screening, 2) remedy-selection
testing, and 3) RD/RA testing. Depending on the technology infor-
mation gathered during RI/FS scoping, pre-ROD treatability studies
may begin at either the remedy-screening or remedy-selection tier.
Remedial design/remedial action treatability testing is performed post-
ROD.
The guide also presents an 11-step generic protocol for conducting
treatability studies. The steps include:
• Establishing data quality objectives
• Identifying sources for treatability studies
• Issuing the Work Assignment
• Preparing the Work Plan
• Preparing the Sampling and Analysis Plan
• Preparing the Health and Safety Plan
• Conducting community relations activities
• Complying with regulatory requirements
• Executing the study
• Analyzing and interpreting the data
• Reporting the results
The intended audience for this guide comprises Remedial Project
Managers, On-Scene Coordinators, Federal facility environmental
coordinators, potentially responsible parties, contractors, and technol-
ogy vendors. Although Resource Conservation and Recovery Act
(RCRA) program officials may find many sections of this guide useful,
the RCRA program is not expressly addressed in the guide.
IV
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TABLE OF CONTENTS
Section Page
NOTICE ii
FOREWORD iii
ABSTRACT iv
FIGURES vi
TABLES vii
ACRONYMS viii
ACKNOWLEDGMENTS ix
1. Introduction 1
1.1 Background 1
1.2 Purpose 1
1.3 Intended Audience 1
1.4 History of the Guide 2
1.5 Use of the Guide 2
2. Overview of Treatability Studies 5
2.1 The Role of Treatability Studies Under CERCLA 5
2.2 Three-Tiered Approach to Treatability Testing 7
2.3 Applying the Tiered Approach 12
2.4 Treatability Study Test Objectives 13
2.5 Special Issues 15
3. Protocol for Conducting Treatability Studies 23
3.1 Introduction 23
3.2 Establishing Data Quality Objectives 23
3.3 Identifying Sources for Treatability Studies 26
3.4 Issuing the Work Assignment 29
3.5 Preparing the Work Plan 31
3.6 Preparing the Sampling and Analysis Plan 35
3.7 Preparing the Health and Safety Plan 38
3.8 Conducting Community Relau'ons Activities 39
3.9 Complying With Regulatory Requirements 41
3.10 Executing the Study 45
3.11 Analyzing and Interpreting the Data 46
3.12 Reporting the Results 52
REFERENCES 55
APPENDIX A. Sources of Treatability Information 57
APPENDIX B. Cost Elements Associated with Treatability Studies 61
APPENDIX C. Technology-Specific Characterization Parameters 65
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FIGURES
Figure Page
1 Decision tree showing when treatability studies are needed to support the evaluation and selection of an
alternative 6
2 The role of treatability studies in the RI/FS and RD/RA process 9
3 Flow diagram of the tiered approach 14
4 Information contained in the ORD Inventory of Treatability Study Vendors 28
5 Example test matrix for zeolite amendment remedy-selection treatability study 32
6 Example project schedule for a two-tiered chemical dehalogenation treatability study 36
7 Example project organization chart 37
8 Facility requirements for treatability testing 42
9 Shipping requirements for offsite treatability testing 43
10 Evaluation criteria and analysis factors for detailed analysis of alternatives 48
11 General applicability of cost elements to various treatability study tiers 62
VI
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TABLES
Table
1 General Comparison of Remedy-Screening, Remedy-Selection, and RD/RA Treatabiliiy Studies 8
2 Aqueous Field Treatability Studies: Generic Versus Vendor Processes 20
3 Soils/Sludges Field Treatability Studies: Generic Versus Vendor Processes 20
4 Summary of Three-Stage DQO Development Process 24
5 PARCC Parameters 25
6 Suggested Organization of Treatability Study Work Assignment 30
7 Suggested Organization of Treatability Study Work Plan 31
8 Typical Waste Parameters Needed to Obtain Disposal Approval at an Offsite Facility 34
9 Suggested Organization of a Treatability Study Sampling and Analysis Plan 38
10 Suggested Organization of a Treatability Study Health and Safety Plan 39
11 Suggested Organization of Community Relations Plan 40
12 Regional Offsite Contacts for Determining Acceptability of Commercial Facilities
to Receive CERCLA Wastes 45
13 Suggested Organization of Treatability Study Report 53
14 Waste Feed Characterization Parameters for Biological Treatment 66
15 Waste Feed Characterization Parameters for Physical/Chemical Treatment 67
16 Waste Feed Characterization Parameters for Immobilization 71
17 Waste Feed Characterization Parameters for Thermal Treatment 72
18 Waste Feed Characterization Parameters for In Situ Treatment 74
vn
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ACRONYMS
AOC Administrative Order on Consent OSWER
ARAR applicable or relevant and appropriate
requirement PARCC
ARCS Alternative Remedial Contracts Strategy
ATTIC Alternative Treatment Technology PAH
Information Center PCB
CERCLA Comprehensive Environmental Response, PRP
Compensation, and Liability Act of 1980 (aka QAPP
Superfund) QA/QC
CFR Code of Federal Regulations RA
COLIS Computerized On-Line Information Service RCRA
COE U.S. Army Corps of Engineers
CRP Community Relations Plan RD
DOD Department of Defense RD&D
DOE Department of Energy RFP
DOT Department of Transportation RI
DQO Data quality objective ROD
EPA U.S. Environmental Protection Agency RPM
ERCS Emergency Response Cleanup Services RREL
ERT Emergency Response Team SAP
ETSC Engineering Technical Support Center SARA
FAR Federal Acquisition Regulations
FR Federal Register SCAP
FS feasibility study
FSP Field Sampling Plan SITE
HSP Health and Safety Plan
HSWA Hazardous and Solid Waste Amendments of SOP
1984 SOW
ITSV Inventory of Treatability Study Vendors START
LDRs Land Disposal Restrictions
MCLs Maximum Contaminant Levels TAT
MSDS Material Safety Data Sheet TCLP
NCP National Oil and Hazardous Substances TIX
Pollution Contingency Plan TOC
NIOSH National Institute for Occupational Safety and TOX
Health TSDF
NPL National Priorities List TSC
O&M Operation and Maintenance TSP
OERR Office of Emergency and Remedial Response TST
ORD Office of Research and Development USCG
OSC On-Scene Coordinator USPS
OSHA Occupational Safety and Health Administration UST
Office of Solid Waste and Emergency
Response
Precision, Accuracy, Representativeness,
Completeness, and Comparability
Polynuclear Aromatic Hydrocarbon
Polychlorinated biphenyl
Potentially responsible party
Quality Assurance Project Plan
quality assurance/quality control
remedial action
Resource Conservation and Recovery Act
of 1976
remedial design
research, development, and demonstration
request for proposal
remedial investigation
Record of Decision
Remedial Project Manager
Risk Reduction Engineering Laboratory
Sampling and Analysis Plan
Superfund Amendments and Reauthoriza-
tion Act of 1986
Superfund Comprehensive
Accomplishments Plan
Superfund Innovative Technology
Evaluation
standard operating procedure
Statement of Work
Superfund Technical Assistance Response
Team
Technical Assistance Team
toxicity characteristic leaching procedure
Technical Information Exchange
total organic carbon
total organic halogen
treatment, storage, or disposal facility
Technical Support Center
Technical Support Project
Technical Support Team
United States Coast Guard
United States Postal Service
Underground Storage Tank
via
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ACKNOWLEDGMENTS
This guide was prepared for the U.S. Environmental Protection Agency, Office of
Research and Development, Risk Reduction Engineering Laboratory (RREL), Cincin-
nati, Ohio, by IT Corporation. Mr. Eugene F. Harris and Mr. David L. Smith served
as the EPA Technical Project Monitors, assisted by Ms. Robin M. Anderson, Office
of Emergency and Remedial Reponse, and Mr. Jonathan Herrmann, RREL. Mr.
Gregory D. McNelly was IT'S Work Assignment Manager. The project team included
Jeffrey S.Davis, Mary Beth Foerst, E.RadhaKrishnan, Jennifer Platt, Michael Taylor,
and Julie Van Deuren. Ms. Judy L. Hessling served as IT's Senior Reviewer, and Ms.
Martha H. Phillips served as the Technical Editor. Document layout was provided by
Mr. James I. Scott, III.
The following personnel have contributed their time and comments by participating in
the Guide for Conducting Treatability Studies Under CERCLA workshop:
Lisa Askari
John Barich
Edward Bates
Benjamin Blaney
John Blevins
Randall Breeden
JoAnn Camacho
Jose Cisneros
Paul Flathman
Vance Fong
Frank Freestone
Tom Greengard
Eugene Harris
Sarah Hokanson
Norm Kulujian
Donna Kuroda
John Quander
Jim Rawe
Ron Turner
U.S. EPA, Office of Solid Waste
U.S. EPA, Region X
U.S. EPA, Risk Reduction Engineering Laboratory
U.S. EPA, Risk Reduction Engineering Laboratory
U.S. EPA, Region IX
U.S. EPA, Office of Emergency and Remedial Response
U.S. EPA, Environmental Response Team
U.S. EPA, Region V Emergency Response
OHM Remediation Services Corporation
U.S. EPA, Region IX
U.S. EPA, Risk Reduction Engineering Laboratory
EG&G Rocky Flats
U.S. EPA, Risk Reduction Engineering Laboratory
Clean Sites, Inc.
U.S. EPA, Region III
U.S. Army Corps of Engineers
U.S. EPA, Technology Innovation Office
Science Applications International Corporation
U.S. EPA, Risk Reduction Engineering Laboratory
IX
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SECTION 1
INTRODUCTION
1.1 Background
Under the Superfund Amendments and Rcaulhorizaiion
Act of 1986 (SARA), the U.S. Environmental Protection
Agency (EPA) is required to select remedial actions in-
volving treatment that "permanently and significantly re-
duces the volume, toxicity, or mobility of the hazardous
substances, pollutants, and contaminants" [Comprehensive
Environmental Response, Compensation, and Liability Act
(CERCLA), Section 121(b)].
Selection of remedial actions involves several risk manage-
ment decisions. Uncertainties with respect to performance,
reliability, and cost of treatment alternatives underscore the
need for well-planned, well-conducted, and well-docu-
mented treatability studies, as evident in the following
quote from Management Review of the Superfund Program
(EPA 1989a):
"To evaluate the application of treatment tech-
nologies to particular sites, it is essential to con-
duct laboratory or pilot-scale tests on actual wastes
from the site, including, if needed and feasible,
tests of actual operating units prior to remedy
selection. These 'treatability tests' are not currently
being performed at many sites to the necessary
extent, or their quality is not adequate to support
reliable decisions."
Treatability studies provide valuable site-specific data nec-
essary to support Superfund remedial actions. They serve
two primary purposes: 1) to aid in the selection of the
remedy, and 2) to aid in the implementation of the selected
remedy. Treatability studies conducted during a remedial
investigation/feasibility study (RI/FS) indicate whether a
given technology can meet the expected cleanup goals for
the site and provide important information to aid in remedy
selection, whereas ircaiability studies conducted during
remedial design/remedial action (RD/RA) establish the de-
sign and operating parameters necessary for optimization
of technology performance and implementation of a sound,
cost-effective remedy. Although the purpose and scope of
these studies differ, they complement one another because
information obtained in support of remedy selection may
also be used to support the remedy design and implementa-
tion. Treatability studies also may be conducted under the
CERCLA Removal Program to support removal actions
that involve treatment.
Historically, instability studies have been delayed until after
the Record of Decision (ROD) has been signed. Although
certain post-ROD treatability studies are appropriate, con-
ducting treatability studies during the RI/FS (i.e., pre-ROD)
should reduce the uncertainties associated with selecting the
remedy, provide a sounder basis for the ROD, and possibly
facilitate negotiations with potentially responsible panics with-
out lengthening the overall cleanup schedule for the site.
Because instability studies may be expensive and time-
consuming, however, the economics of cost and lime must be
taken into consideration when planning ireatability studies in
support of the various phases of ihc Superfund program.
1.2 Purpose
This document presents guidance on conducting ireatability
siudies under CERCLA. Iis purpose is lo facilitate efficient
planning, execution, and evaluation of ircaiability studies
and to ensure that the data generated can support remedy
selection and implcmcniaiion.
1.3 Intended Audience
This document is intended for use by EPA Remedial Project
Managers (RPMs), EPA On-Sccnc Coordinators (OSCs),
poicniially responsible parlies (PRPs), Federal facilily en-
vironmental coordinators, trcaiability sludy contractors, and
technology vendors. As described here, each of ihcsc
persons plays a different role in conducting ircatabilily
studies under CERCLA. Although the Resource Conscrva-
lion and Recovery Act (RCRA) program is not expressly
-------
addressed, many sections of the guide may be useful in the
planning of treatabilily studies in support of corrective
action. Some parts may also be applicable in the Under-
ground Storage Tank (UST) program.
1.3.1 Remedial Project Managers
Remedial Project Managers are EPA or State officials re-
sponsible for remediation planning and oversight at a site.
Their role in treatability investigations depends on the des-
ignated lead agency (Federal, State, or private) and whether
the site is a fund-financed or enforcement-lead site. Their
activities generally include scoping the treatability study,
establishing the data quality objectives, selecting a contrac-
tor, and issuing a work assignment, or obtaining EPA-
sponsored treatability study support, overseeing the execu-
tion of the study, informing or involving the public as
appropriate, reviewing project deliverables, and using
treatability study data in decision making.
7.3.2 On-Scene Coordinators
On-Scene Coordinators are Federal officials predcsignatcd
by the EPA or U.S. Coast Guard (USCG) to coordinate and
direct removal actions at both National Priorities List (NPL)
and non-NPL sites. Their role in treatability studies is
similar to that of the RPM.
1.3.3 Potentially Responsible Parties
Under CERCLA Sections 104(a) and I22(a), EPA has the
discretion to allow PRPs to perform certain RI/FS activi-
ties, including treatabilily studies. The EPA or an autho-
rized State agency oversees the conduct of PRP-lcd
treatability studies, but the PRP is responsible for project
planning, execution, and evaluation.
7.3.4 Federal Facility Environmental
Coordinators
Environmental coordinators at Federal facilities may con-
duct treatability studies under CERCLA or agency-specific
programs such as the Department of Defense (DOD) Instal-
lation Restoration Program and the Department of Energy
(DOE) Environmental Restoration and Waste Management
Program. The roles and responsibilities of these personnel
will vary by agency and program; however, for treatabilily
studies they will be similar to those of the EPA RPM.
7.3.5 Contractors/Technology Vendors
Treatability studies are generally performed by remedial
contractors or technology vendors. Their roles in treatability
investigations include preparing the Work Plan and other
supporting documents, complying with regulaiory require-
ments, excculing ihc study, analyzing and interpreting the
data, and reporting the results.
1.4 History of the Guide
In December 1989, EPA published the interim final Guide
for Conducting Treatabilily Studies Under CERCLA (EPA
1989b). This generic treatabilily guidance was one compo-
nent of the EPA's Office of Research and Development
(ORD) ireaiabilily sludy initiative to identify trcaiabiliiy
capabiliiies, to consolidate treatability data, and to develop
standard operating protocols. The objectives of the guide
were threefold:
1) To provide guidance to RPMs and Supcrfund re-
medial contractors for conducting treatability stud-
ies in support of remedy selection (i.e., prc-ROD).
2) To serve as a framework for developing technol-
ogy-specific protocols.
3) To be a dynamic document that evolves as the
Agency gains instability study experience.
As part of the development of the generic treatability guid-
ance, EPA sponsored a treatabilily proiocol workshop in
July 1989, which was aiiendcd by more than 60 represenia-
lives from EPA Headquarters and Regional offices, con-
tractors/technology vendors, and academia. The tiered
approach to treatability studies and the 11-step proiocol
thai evolved during ihe workshop and subsequenl docu-
ment peer review process form the basis of the treatabilily
guidance.
In keeping with ihe original objective of producing a dy-
namic document, comments on the ulilily of the interim
final guidance after approximaiely 18 monihs of use were
soliciied through a survey of potential users (principally
RPMs and their contractors) and a second workshop in
August 1991. Although Ihc general conteni and formal
have noi changed, ihc document has been expanded to
address a broader audience and updated to reflect current
regulations, policy, and guidance/informaiion sources. In
addiiion, the "tier" terminology has been revised to reflect
the intended use of the data rather than the scale of testing.
1.5 Use of the Guide
7.5.7 Organization of the Guide
The guide is organized into two principal sections: an
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overview of treatability studies and a step-by-step protocol.
Section 2 describes the need for treatability studies and
presents a three-tiered approach consisting of 1) remedy
screening, 2) remedy selection, and 3) remedial design/
remedial action. This section also describes the application
of the tiered approach to innovative technologies, treatment
trains, and in situ technologies; circumstances in which
treatability studies can and cannot be performed generi-
cally; and PRP-conducted treatability studies.
Section 3 presents a general approach or protocol for con-
ducting treatability studies. It contains information on
planning, performing, and reporting the results of treatability
studies with respect to the three tiers. Specifically, this
section includes information on:
• Establishing data quality objectives.
• Identifying qualified sources for performance of
treatability studies and selecting a contracting mecha-
nism.
• Issuing the work assignment, with emphasis on writ-
ing the scope of work.
• Preparing the Work Plan, with emphasis on designing
the experiment.
• Preparing the Sampling and Analysis Plan for a
treatability study.
• Preparing the Health and Safety Plan for a treatability
study.
• Conducting community relations activities in support
of treatability studies.
• Complying with regulatory requirements for testing
and residuals management.
• Executing the treaiabilily study, with emphasis on col-
lecting and analyzing samples.
• Analyzing and interpreting the data, including a dis-
cussion on statistical analysis techniques.
• Reporting the results in a logical and consistent format.
The text of each subsection presents general information
followed (when applicable) by specific details pertaining to
the three tiers of treaiability testing.
Appendix A contains additional sources of treatability
information. Appendix B discusses the major cost ele-
ments associated with treaiabilily studies. Appendix C
contains technology-specific waste-characterization pa-
rameters.
7.5.2 Application and Limitations of the
Guide
Treatability studies are an integral part of the Superfund
program. This guide is intended to supplement the infor-
mation on development, screening, and analysis of alterna-
tives contained in the interim final Guidance for Conduct-
ing Remedial Investigations and Feasibility Studies Under
CERCLA (EPA 1988a). hereinafter referred to as the RI/FS
guidance. Generic in nature, the guide encompasses all
waste matrices (soils, sludges, liquids, and gases) and all
categories of technologies (biological treatment, physical/
chemical treatment, immobilization, thermal treatment, and
in situ treatment). The guide addresses instability studies
conducted in support of remedy screening and selection
(i.e., pre-ROD) and remedy design and implementation
(i.e., post-ROD). Companion documents providing tech-
nology-specific treatability guidance are being prepared for
soil vapor extraction, chemical dchalogenation, soil wash-
ing, solvent extraction, biodcgradation, thermal dcsorption,
and solidification/stabilization.
In an effort to be concise, supporting information in other
readily available guidance documents is referenced through-
out this guide rather than repeated. For example, details on
the preparation of a site Sampling and Analysis Plan (which
includes a Field Sampling Plan and a Quality Assurance
Project Plan), a Health and Safety Plan, and a Community
Relations Plan are not included herein.
Although ihis guidance is wriucn 10 support the treatability
study activiiies of an EPA RPM under CERCLA, it has
wide applicability to many oihcr programs. For this reason,
the term "project manager" has been used, when appropri-
ate, to signal the potential applicability of the subject cov-
ered to both the CERCLA Remedial and Removal Pro-
grams and to non-CERCLA treaiability studies.
This document was drafted and reviewed by representa-
tives from EPA's Office of Solid Waste and Emergency
Response, Office of Research and Development, and the
Regional offices, as well as by contractors and vendors
who conduct treatability studies. Comments obtained dur-
ing ihe course of the peer review process have been inte-
grated or addressed throughout this guide.
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SECTION 2
OVERVIEW OF TREATABILITY STUDIES
This section presents an overview of treatability studies
under CERCLA and provides examples of the application
of treatability studies in the RI/FS process. Subsection
2.1 outlines the role of treatability studies in the Super-
fund program. Subsection 2.2 provides details on the
three tiers of treatability testing. Subsection 2.3 presents
the methodology for applying the tiered approach. Sub-
section 2.4 discusses treatability study test objectives.
Subsection 2.5 addresses special issues associated with
CERCLA treatability studies, including examples of how
the tiered approach can be applied to investigations of unit
operations, treatment trains, and in situ technologies; when
testing can and cannot be performed generically (i.e.,
without the assistance of vendors using proprietary re-
agents and processes); the involvement and oversight of
PRPs; and the funding of treatability studies.
2.1 The Role of Treatability Studies
Under CERCLA
2.1.7 Pre-ROD Treatability Studies
As discussed in the RI/FS guidance, site characterization
and treatability investigations are two of the main compo-
nents of the RI/FS process. As site and technology infor-
mation is collected and reviewed, additional data needs
for evaluating alternatives arc identified. Trcatabilily
studies may be required to fill some of these data gaps.
In the absence of data in the available technical literature,
treatability studies can provide the critical performance
and cost information needed to evaluate and select treat-
ment alternatives. The purpose of a pre-ROD trcatability
investigation is to provide the data needed for the detailed
analysis of alternatives during the FS. The 1990 revised
National Oil and Hazardous Substances Pollution Contin-
gency Plan (NCP) (55 FR 8813), Section 3()().430(c),
specifies nine evaluation criteria to be considered in this
assessment of remedial alternatives. Trcatabilily studies
can generally provide data to address the first seven of
these nine criteria:
1) Overall protection of human health and the
vironmcnt
en-
2) Compliance with applicable or relevant and ap-
propriate requirements (ARARs)
3) Long-term effectiveness and permanence
4) Reduction of toxicity, mobility, and volume
through treatment
5) Short-term effectiveness
6) Implemenuibility
7) Cost
8) State acceptance
9) Community acceptance
The first two criteria, which relate directly to the statutory
requirements each remedial alternative must meet, are
categorized as threshold criteria. The next five are the
primary balancing criteria upon which the selection of
the remedy is based. The final two modifying criteria,
State acceptance and community acceptance, arc addressed
in the ROD when comments arc received on the RI/FS and
the proposed remedial plan. (The RI/FS evaluation crite-
ria are discussed in detail in Subsection 3.11.2.)
Pre-ROD trcatability studies may be needed when poten-
tially applicable treatment technologies arc being consid-
ered for which no or limited performance or cost informa-
tion is available in the literature with regard to the waste
-------
types and site conditions of concern. The general decision
tree presented in Figure 1 illustrates when ireatabiliiy
studies are needed to support the evaluation and selection
of an alternative. After the existing data on the physical
and chemical characteristics of the waste have been re-
viewed, a literature survey is conducted to obtain any
existing ireatability data for the contaminants and matri-
ces of concern. (Sources of technical support and
treatability information available through EPA are dis-
cussed in Subsection 3.3 and Appendix A.) Based on the
results of a review of available site data and a literature
search, remedial technology types are prcscreencd to elimi-
nate those that arc clearly not applicable for the site.
Potentially and definitely applicable technologies are as-
sembled into alternatives and evaluated in terms of the
nine RI/FS criteria to identify any data gaps. Site- and
technology-specific data needs are then identified for each
of the alternatives retained for investigation.
The need to conduct a treatabilily study on any part of an
alternative is a management decision. In addition to the
technical considerations, certain nontechnical management
decision factors must be considered. As shown in Figure
1, these factors include the expected level of State and
community acceptance of a proposed alternative; lime
constraints on the completion of the RI/FS and the signing
of the ROD; and the appearance of new site, waste, or
technology data.
If the existing data arc adequate for an evaluation of the
alternative for remedy selection (i.e., sufficient to perform
a detailed analysis against the nine RI/FS evaluation crite-
ria), no treatability study is required. Otherwise, a
ireatability study should be performed to generate the data
necessary to conduct a detailed analysis of the alternative.
2.1.2 Post-ROD Treatability Studies
Although a substantial amount of data on the selected
remedy may be available from the RI/FS, treatabilily stud-
ies may also be necessary during remedial design/reme-
dial action if treatment is part of ihc remedy. Posi-ROD
or RD/RA ireaiabilily sludies can provide the detailed
design, cost, and performance daia needed 10 optimize
treatment processes and to implement full-scale ircatmcni
systems. In ihe process of implemcniing a remedy, RD/
RA treatability studies can be used 1) lo sclcci among
multiple vendors and processes within a prescribed rem-
edy (prequalification), 2) 10 implement the most appropri-
ate of ihe remedies prescribed in a Comingcncy ROD, or
3) 10 suppori preparaiion of the Agency's detailed design
specifications and ihe design of treatment trains.
REVIEW AVAILABLE
SITE DATA
SEARCH LITERATURE
TO OBTAIN EXISTING
TREATABILITY DATA
IDENTIFY
DATA GAPS
YES
AflE DATA
ADEQUATE TO EVALUATE
ALTERNATIVE?
MANAGEMENT DECISION FACTORS.
• SUM jndCommunMy Accepting |
• Scfudul* Consrjna
• Addftraral Oiu
PERFORM \
DETAILED ANALYSIS I
OF ALTERNATIVES I
Figure 1. Decision tree showing when
treatability studies are needed to support the
evaluation and selection of an alternative.
The need for RD/RA treatability studies may be identified by
the RPM, ihe PRP, or the remedial designer—Alternative
Remedial Contracts Strategy (ARCS) contractor or U.S. Army
Corps of Engineers (COE). Because the designer is ulti-
mately responsible for the remedial design, ihe designer should
carefully review ihe available site-, technology-, and waste-
specific trcatability data before deciding on whether an RD/
RA ireatability siudy will be needed.
Vendor/Process Prequalification
In general, a single remedy is sclccicd in ihe ROD. The
remedy is often identified as a icchnology class or family
(e.g., ihcrmal dcsiruciion) rather than as a specific process
option (e.g., a rotary kiln). Selection of a treatment class
affords flexibility during the remedial design to procure
the most cost-cffeciivc vendor and process.
One method of selecting an appropriate vendor or process
is to use RD/RA treaiabilily siudy results to "prcqualify" a
pool of vendors. In these studies, all intcrcsicd parlies arc
-------
provided with a standard sample of waste. Each vendor
designs and performs a treatability study based on that
sample and provides treatment results to the lead agency.
The lead agency uses these results to determine which
vendors are qualified to bid on the RA. Generally, the
vendor should achieve results equivalent to the cleanup
criteria defined in the ROD to be considered for
prequalification.
This prequalification approach has been used at the Selma
Treating Company Superfund Site, Region 9, Selma, Cali-
fornia. Part 9 of the Federal Acquisition Regulations
(FAR) describes policies, standards, and procedures ap-
plicable to this approach.
Contingency RODs
There are situations in which additional flexibility in the
ROD may be required to ensure implementation of ihe
most appropriate technology for a site. In these cases, the
selected remedy may be accompanied by a proven contin-
gency remedy in a Contingency ROD. The Contingency
ROD option was developed for two purposes: 1) to pro-
mote the use of innovative technologies, and 2) to allow
different technologies offering comparable performance
to be carried through to remedial design.
Although treatability studies of an innovative technology
will be conducted during the RI/FS to support remedy
selection, it may not be feasible to conduct sufficient
testing to address all of the significant uncertainties asso-
ciated with the implementation of this option. This situa-
tion, however, should not cause the option to be screened
out during the detailed analysis of alternatives in the FS.
If the performance potential of an innovative technology
indicates this technology would provide the best balance
of tradeoffs from among the options considered despite
its uncertainties, CERCLA Section 121(b)(2) provides
support for selecting such a technology in the ROD.
Implementation of the technology, however, may be con-
tingent upon the results of RD/RA treatability testing.
When an innovative technology is selected and its perfor-
mance is to be verified through additional treatabilily
testing, a proven treatment technology may also be in-
cluded in the ROD as a contingency remedy. In the event
the RD/RA treatability study results indicate that the full-
scale innovative remedy cannot achieve ihe cleanup goals
at the site, the contingency remedy could then be imple-
mented.
If two different technologies for treatment of the same
contaminant/matrix emerge from the FS and each offers
comparable performance with respect to the five primary
balancing criteria so that either one could provide the best
balance of tradeoffs, one of the alternatives may be named
in the ROD as the selected remedy and the other as the
contingency remedy. Based on the results of post-ROD
RD/RA treatability testing, the most appropriate remedy
can then be identified and implemented.
Detailed Design Specifications
To support the remedial action bid package, the lead
agency may choose to develop detailed design specifica-
tions. If technical data available from the RI/FS are
insufficient for design of the remedy, an RD/RA treat-
ability study may be necessary. Post-ROD treatability
studies can provide the detailed cost and performance data
required for optimization of the treatment processes and
the design of a full-scale treatment system.
If an RD/RA treatability study is required to support the
detailed design specifications, the designer will be re-
sponsible for planning the study and defining the perfor-
mance goals and objectives. Treatability study oversight
will be provided by the RPM and the Oversight Assistant.
Post-ROD RD/RA treatability studies can also be per-
formed to support the design of treatment trains. Al-
though all parts of a treatment train may be effective for
treating the wastes, matrices, and residuals of concern,
issues such as unit sizing, materials handling, and systems
integration must also be addressed. Treatability studies of
one unit's operations can assist in identifying characteris-
tics of the treated material that may need to be taken into
consideration in the design of later units. A treatability
study of the entire train can then provide data to confirm
compliance with ARARs and the cleanup criteria outlined
in the ROD. Because a treatment train will often involve
several different technologies and vendors, the designer
will coordinate treatability testing of the entire system and
prepare the final treatability study report.
2.2 Three-Tiered Approach to
Treatability Testing
Treatability studies are laboratory or field tests designed
to provide critical data needed to evaluate and implement
remedial treatment technologies at waste sites. As an aid
in the planning and performance of cost-effective, on-
time, scientifically sound treaiability studies, a three-
tiered approach has been developed. The three-tiered
approach applies to all treatability studies conducted in
-------
support of Superfund site remediation. Figure 2 presents
the treatability tiers and their conceptual relationship to
the RI/FS and the RD/RA processes. Table 1 lists general
similarities and differences among the three tiers.
2.2.1 Technology Prescreening and
Treatability Study Scoping
Prescreening is an important first step in the identification
of potentially applicable treatment technologies and the
need for treatability testing. Because of the strict time sched-
ules and budget constraints placed on the completion of an
RI/FS, it is crucial for the planning and scoping of treatability
studies to begin as early as possible. As shown in Figure 2,
these efforts should be initiated during the RI/FS scoping.
Technology prescreening and treatability study scoping
will include searching technology literature and treatability
data bases, consulting with technology experts, determin-
ing data needs, identifying potential treatability study sources
or contractors, identifying preliminary data quality objec-
tives, and preparing a work assignment. Determination of
the tier or tiers of treatability testing to be conducted will be
based on the technology- and contaminant-specific data needs.
Technology experts are available within EPA to assist project
managers with technology prescreening and treatability
study scoping. (In-house consultation services available to
EPA project managers are discussed in Subsection 3.3;
additional information is presented in Appendix A.) Early
consultation may save time and money by preventing the
treatability testing of inappropriate technologies.
2.2.2 Remedy Screening
Remedy screening, the first step in the tiered approach,
provides the gross performance data needed to determine
the potential feasibility of the technology for treating the
contaminants and matrix of concern. Remedy-screening
treatability studies may not be necessary when the litera-
ture contains adequate data for an assessment of the feasi-
bility of a technology. The results of a remedy-screening
study are used to determine whether additional, more-de-
tailed treatability testing should be performed at the rem-
edy-selection tier.
Feasibility is determined by assessing how well a technol-
ogy achieves the treatability study's performance goals,
which are based on available knowledge of the operable
unit's cleanup criteria and are set prior to the study. Typi-
cally, remedy-screening studies arc conducted under con-
ditions representative of those in the proposed full-scale
system. If a technology cannot achieve the predetermined
performance goals under these conditions, it should be
screened out. If all technologies arc rejected, the project
manager should reevaluate the screening performance goals
to determine if they arc appropriate.
As shown in Figure 2, remedy-screening treatability stud-
ies are initiated during the prc-ROD site characterization
and technology screening activities and may continue
through the identification of alternatives. General charac-
teristics of the remedy-screening tier (outlined in Table 1)
are discussed here.
Study Scale
Performed in the laboratory, remedy-screening treatability
studies are limited in size and scope to bench-scale tests with
off-the-shelf equipment Investigations of some technologies
may require additional small-scale field tests at the screening tier.
Type of Data Generated
Remedy-screening studies provide qualitative data for use
in assessing the potential feasibility of a technology for
Table 1. General Comparison of Remedy-Screening, Remedy-Selection, and RD/RA Treatability Studies
Tier
Remedy
screening
Remedy
selection
RD/RA
Study scale
Bench scale
Bench or pilot scale
Pilot or full scale
(onsite or offsite)
Full scale
(onsite)
Type
of data
generated
Qualitative
Quantitative
Quantitative
Quantitative
No. of
replicates
Single/
duplicate
Duplicate/
triplicate
Duplicate/
triplicate
Duplicate/
triplicate
Process
type
Batch
Batch or
continuous
Batch or
continuous
Batch or
continuous
Waste
stream
volume
Small
Medium
Large
Large
Time
required3
Days
Days/
weeks
Weeks/
months
Weeks/
months
Cost, S
10,000-
50,000
50,000-
100,000
50,000-
250,000
250,000-
1,000,000
a Indicates duration of testing only.
-------
Scoping
"the RI/FS'
Technology
Prescreening
and
Treatability
Study
Scoping
Remedial Investigation/
Feasibility Study
Record of
Decision
Identification
of Alternatives
I
Remedial Design/
Remedial Action
Remedy
Selection
Site
Characterization
and Technology
Screening
Evaluation
of Alternatives
REMEDY SCREENING
TREATABILITY
to Determine
Potential Feasibility
REMEDY SELECTION
TREATABILITY
to Develop Performance
and Cost Data
Implementation
of Remedy
RD/RA TREATABILITY
to Develop Detailed Design
and Cost Data and to
Confirm Performance
Figure 2. The role of treatability studies in the RI/FS and RD/RA process.
-------
treating a contaminant/matrix combination. No cost or
design information will be generated. The project manager
must determine the overall qualitative data needs based on
the intended use of the information and the availability of
time and funds.
During remedy screening, a single indicator contaminant is
often monitored to determine whether a reduction in toxic-
ity, mobility, or volume is occurring. If a technology
appears to meet or exceed the performance goal for that
contaminant, it is considered potentially feasible and re-
tained for further evaluation. Remedy screening is also
useful for identifying critical parameters for investigation
at the remedy-selection tier.
Number of Replicates
In most cases, little or no test sample replication (single or
duplicate) is required at the screening tier. A less stringent
level of quality assurance/quality control (QA/QC) is suffi-
cient because a technology that is found to be feasible must
still undergo remedy-selection testing before it is selected
in the ROD.
Process Type/Waste Stream Volume
Screening will generally involve batch tests and the use of
small-volume samples of the waste stream. For example,
remedy screening of an ion exchange process designed to
treat aqueous wastes may require sample volumes on the
order of 500 milliliters per run with only three runs through
the test column.
. Time/Cost
The duration and cost of remedy screening depend prima-
rily on the type of technology being investigated and the
number of parameters considered. Generally, remedy screen-
ing can be performed in a few days at a cost of between
510,000 and 550,000. This estimate of duration covers the
time spent in the testing laboratory; it does not include
sample analysis or data validation, as these elements depend
on the analytical laboratory used. Neither does it include the
time required for study planning and reporting. The cost
estimate does include all of these elements, however.
The nature of remedy screening (i.e., simple equipment,
small number of test samples and replicates, less-stringent
QA/QC requirements, and minimum reporting requirements)
makes it the least costly and time-consuming of the three
instability study tiers. Cost and lime savings arc increased
by limiting sampling and analysis objectives to address
only indicator contaminants that are representative of the
families of chemicals present and their concentrations.
2.2.3 Remedy-Selection Testing
Remedy selection is the second step in the tiered approach.
A remedy-selection trcatabilily study is designed to verify
whether a process option can meet the operable unit's
cleanup criteria and at what cost. The purpose of this lier is
to generate the critical performance and cost data necessary
for remedy evaluation in the detailed analysis of alterna-
tives during the FS.
After the feasibility of a treatment alternative has been
demonstrated, either through remedy-screening studies or a
literature review, process operating parameters are investi-
gated at the remedy-selection tier. The choice of param-
eters to be studied is based on the goal of achieving the
operable unit's cleanup criteria and other waste-specific
performance goals. Investigation of equipment-specific
parameters should generally be delayed until posi-ROD
RD/RA studies.
Results of remedy-selection trcatability studies also should
allow for estimating the costs associated with full-scale
implementation of the alternative within an accuracy of
+50/-30 percent, as required for the FS.
As shown in Figure 2, remcdy-selcclion trcatability studies
are initiated during the prc-ROD site characterization and
technology screening activities and continue through the
evaluation of alternatives. General characteristics of the
remedy-selection tier (outlined in Table 1) arc discussed here.
Study Scale
Remedy-selection trcatability studies are performed in the
laboraiory or field wiih bench-, pilot-, or full-scale equip-
ment. The scale of equipment used is often technology-
specific, and it will also depend on the availability of funds
and lime and the data needs. Equipment should be de-
signed to simulate the basic operations of the full-scale
treatment process. Combinations of bench and field icsiing
are also possible ai this licr.
Type of Data Generated
Remedy-selection studies provide quantitative data for use
in determining whether a technology can meet the operable
unit's cleanup criteria and at whai cost. The operational
and performance information resulting from remedy-selec-
tion studies will be used to estimate full-scale treatment
costs and schedules and to assess ihc technology against the
RI/FS evaluation criteria.
For example, bench-scale remedy-selection studies of some
technologies can provide the detailed performance data
10
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needed to assess the technology against the reduction of
toxicity, mobility, or volume criterion. Pilot-scale testing
may identify waste-stream characteristics that could ad-
versely affect the implementability of a technology. Treat-
ment train considerations, such as the need for further
processing of treated waste or treatment residuals, can also
be addressed at this tier.
When planning remedy-selection treatability studies, the
project manager, in consultation with management, must
determine the overall quantitative data needs for a technol-
ogy based on the intended use of the information and the
availability of time and funds. Early consultation with
technology experts and vendors is important when deter-
mining data needs for innovative and proprietary technolo-
gies.
Number of Replicates
Remedy-selection treatability studies require duplicate or
triplicate test sample replication. Because the data gener-
ated at this tier will be used for remedy selection in the
ROD, moderately to highly stringent levels of QA/QC are
required. A stringent level of QA/QC is needed to increase
the confidence in the decision that the selected remedy can
achieve the cleanup goals for the site.
Process Typel Waste Stream Volume
Remedy-selection treatability studies may be conducted as
either a batch or a continuous process. Waste-stream sample
volumes should be adequate to simulate full-scale opera-
tions. For example, the waste-stream volume needed to
perform continuous, bench-scale testing of an ion exchange
treatment process for an aqueous waste may be on the order
of 1 liter per minute for a treatment duration of 8 hours
(which would require approximately 500 liters of waste).
Waste-handling operations, such as pretreatment blending,
also should be designed to simulate those expected for full-
scale treatment.
Time/Cost
The duration and cost of remedy-selection testing depend
primarily on the type of technology being investigated, the
types of analyses being performed, and the level of QA/QC
required. Most bench-scale studies can be performed within
a period of days to weeks. Pilot-scale testing usually
requires a longer period (i.e., weeks to months). This
estimate covers only the actual performance of the lest. It
does not include sample analysis or data validation, as
these elements depend on the analytical laboratory used;
nor does it include study planning and reporting. Depend-
ing on its scale and complexity, a remedy-selection
treatability study can be performed at a cost of between
550,000 and 5250,000, including analytical support.
The higher cost and longer time requirements of remedy-
selection treatability testing compared with remedy screen-
ing are directly related to the need for stringent QA/QC and
the greater number of test samples and replicates to be
analyzed.
2.2.4 RD/RA Testing
Treatability testing to support RD/RA activities is the final
step in the three-tiered approach. The purpose of an RD/
RA treatability study is to generate the detailed design,
cost, and performance data necessary to optimize and imple-
ment the selected remedy. As shown in Figure 2, RD/RA
treatability studies are conducted after the ROD has been
signed. These studies are performed 1) to select among
multiple vendors and processes within a prescribed remedy
(prequalification), 2) to implement the most appropriate of
the remedies prescribed in a Contingency ROD, and 3) to
support the Agency's detailed design specifications (if pre-
pared) and the design of treatment trains. Most RD/RA
treatability studies are performed by remediation contrac-
tors and technology vendors. The EPA RPM monitors the
performance of these studies and reviews the results to
assess their acceptability with regard to the ROD, RA
goals, and, if applicable, the settlement agreement Gen-
eral characteristics of the RD/RA tier (outlined in Table 1)
are discussed here.
Study Scale
Most RD/RA treatability studies are performed in the field
wiih pilot- or full-scale equipment. Some prequalification
treatability studies will be performed in the laboratory;
however, the system should closely approximate the pro-
posed full-scale operations.
Type of Data Generated
Remedial design/remedial action ircatability studies pro-
vide the detailed, quantitative design and cost data required
to optimize critical parameters and to implement the se-
lected remedy. The following arc issues that may be ad-
dressed with RD/RA study daia:
• Full-scale performance
• Treatment train performance
• Materials-handling characteristics
• Process upset and recovery
11
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• Side-stream and residuals generation and treatment
• Energy and reagent usage
• Site-specific considerations, such as heavy equipment
access and waste-feed staging space
• Field-screening analytical methods
The parameters investigated at the RD/RA tier may include
feed rates (continuous processes), number of treatment
cycles (batch processes), mixing rates, heating rates, and
other equipment-specific parameters. Remedial design/
remedial action testing also may identify waste-stream char-
acteristics that could adversely affect the implementability
of the full-scale system.
When planning RD/RA treatability studies, the technology
vendor, in consultation with the designer and the lead
agency, must determine the overall quantitative data needs
for a technology based on the intended use of the informa-
tion. Early consultation with vendors is important in the
determination of data needs for proprietary technologies.
Number of Replicates
Remedial design/remedial action treatability studies usu-
ally require duplicate or triplicate test sample replication.
The data generated at this tier are used to design and
optimize the process; therefore, stringent levels of QA/QC
are required.
In the case of prequalification treatability studies, QA/QC
requirements will be determined by the designer. The num-
ber and types of samples to be submitted by vendors will be
outlined in the designer's prequalification announcement.
Process Type/Waste-Stream Volume
Remedial design/remedial action treatability studies may
be conducted as either a batch or a continuous process,
depending on the operation of the full-scale system. Waste-
stream sample throughput and volume should achieve lev-
els projected for full-scale operations. For example, the
waste-stream sample volume needed to perform continu-
ous, full-scale testing of an ion exchange treatment process
for an aqueous waste may be on the order of 25 liters per
minute for a treatment duration of 16 hours per day for 21
days (which would require more than 500,000 liters of waste).
Time/Cost
Because of the potentially significant mobilization require-
ments associated with any onsite operation, performing
RD/RA treatability studies is significantly more time-con-
suming and costly than pre-ROD studies. The duration and
cost depend primarily on the type of technology being
investigated, the types of analyses being performed, and
the level of QA/QC required. Most RD/RA studies can be
performed within a period of weeks to months. This esti-
mate covers only the actual performance of the test. It does
not include the time required for mobilization, construc-
tion, shakedown, or demobilization of the unit, as these
procedures are specific to the site and to the technology
being tested; sample analysis or data validation, as these
elements depend on the analytical laboratory used; or study
planning and reporting. Most RD/RA trcatability studies
can be performed at a cost of between 5250,000 and
SI,000,000.
Prequalification treatability testing is an exception to these
time and cost estimates because the tests are performed at
the vendors' cost. Analytical support, however, is usually
provided by the Agency.
2.3 Applying the Tiered Approach
The purpose of a pre-ROD trcatability investigation is to
generate data needed for a detailed analysis of the alterna-
tives and, ultimately, the selection of a remedial action that
can achieve the operable unit's cleanup criteria. Pre-ROD
trcatability studies are performed to enable the decision
maker to evaluate all treatment and nontreatment alterna-
tives on an equal basis.
The need for pre-ROD treatability testing at a Superfund
site is a risk-management decision in which the cost and
time required to conduct treatability studies are weighed
against the risks inherent in the selection of a remedial
technology. Factors in this decision are specific to the
waste matrix, waste contaminants, and treatment technol-
ogy. Determining whether pre-ROD treatability studies
should be conducted may also depend on such nontechnical
factors as State and community acceptance of an alterna-
tive; time constraints on the completion of the RI/FS and
the ROD; and the discovery of new operable unit-, waste-.
or technology-based data that may have an impact on treat-
ment performance.
Of the management decision factors listed, schedule con-
straints may be of the most consequence. The performance
of pre-ROD trcatability studies that were planned and sched-
uled early (i.e., during the scoping of the RI/FS) generally
should not delay the ROD. In some instances, however, the
need for treatability studies may conflict with RI/FS and
ROD schedule commitments. For example, if an innova-
tive technology is being considered as pan of an altema-
12
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live, significant gaps in the technical literature may lengthen
the time required to plan and perform a thorough treatability
investigation. When the potential benefits of the inno-
vative technology are known, pursuing the treatability study
at the expense of ROD scheduling goals may be appropri-
ate. The EPA's Guidance for Increasing the Application of
Innovative Treatment Technologies for Contaminated Soil
and Ground Water (EPA 199la) and its cover memoran-
dum indicate the Agency's willingness to adjust program
goals and commitments, when appropriate, to achieve bet-
ter cleanup solutions through innovative treatment technol-
ogy development.
The flow diagram in Figure 3 traces the stepwise data
reviews and management decisions that occur in the tiered
approach. Site characterization and technology
prescreening/treatability study scoping initiate the process.
Technologies that are determined to be potentially appli-
cable (based on effectiveness, implementabiliiy, and cost)
are retained as alternatives; all others are screened out. The
decision to conduct a trcatability study on an alternative is
based on the availability of technology-specific treatability
information and on inputs from management. If a treat-
ment technology is well demonstrated for the particular
contaminants/matrix and sufficient information exists to
permit its evaluation against the nine evaluation criteria in
the detailed analysis of alternatives, a pre-ROD treatability
study is not required.
If significant questions remain about the feasibility of a
technology for remediating an operable unit, a remedy-
screening treatability study should be performed. Innova-
tive technologies or wastes that have not been extensively
investigated should almost always be subjected to instability
testing at this tier. If a technology has been shown to be
effective at treating the contaminants/matrix of concern but
insufficient information exists for detailed analysis, the
remedy-screening tier may be bypassed in favor of a rem-
edy-selection treatability study. If a remedy-selection study
indicates that a technology can meet the cleanup criteria, a
detailed analysis of this alternative should then be per-
formed. If the alternative is selected in the ROD, a posi-
ROD RD/RA treatability study may be required to design
and optimize the full-scale system, to obtain detailed cost
data, and to confirm performance.
2.4 Treatability Study Test Objectives
Each tier of treatability testing is defined by its particular
purpose: remedy screening, to determine potential feasibil-
ity; remedy selection, to develop performance and cost
data; and RD/RA, to develop detailed design and cost data
and to confirm full-scale performance. For achievement of
these purposes, the planning and design of treatability stud-
ies must reflect specific, predetermined test objectives.
Depending on the tier of testing, test objectives may call for
making qualitative engineering assessments, achieving quan-
titative performance goals, or both. Because test objectives
are technology-, matrix-, and contaminant-specific, setting
universal objectives for each tier of testing is impossible.
Qualitative assessments of performance are often appropri-
ate at the remedy-screening tier. Simply demonstrating a
reduction in contaminant concentration, for example, may
be sufficient to confirm the potential feasibility of using an
innovative treatment technology. For other technologies, a
quantitative performance goal such as 50 percent reduction
in contaminant mobility might indicate the potential to
achieve greater reduction through process refinements and
thus confirm the feasibility of a process option and justify
additional testing at the remedy-selection tier.
Test objectives at the remedy-selection tier will include
achieving quantitative performance goals based on the an-
ticipated cleanup criteria to be established in the ROD. For
example, if the cleanup criterion for a contaminant in the
soil at a site is 1 ppm, the performance goal for a remedy-
selection treatabilily study might also be 1 ppm. If no
cleanup criteria have been established for the site, a 90
percent reduction in the contaminant concentrations will
generally be an appropriate performance goal. This level
of performance is in agreement with EPA's guideline es-
tablished in the 1990 revised NCP, which stales that". . .
treatment as part of CERCLA remedies should generally
achieve reductions of 90 to 99 percent in the concentration
or mobility of individual contaminants of concern, although
there will be situations where reductions outside the 90 to
99 percent range that achieve health-based or other site-
specific remediation goals (corresponding to greater or
lesser reductions) will be appropriate" (55 FR 8721). Ad-
ditional guidelines upon which a project manager should
base remedy-selection performance goals are as follows:
• Protection of human health and the environment
• Compliance with ARARs
• Attainment of contaminant levels acceptable for waste
dclisting
• Attainment of contaminant levels accepted by the Slate
or Region at other sites with similar waste characteristics
Remedy-selection treatability studies will generally have
additional pre-ROD icsi objectives designed to provide the
specific cost and engineering information necessary for a
detailed analysis of the alternative. Cost data should be
13
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SITE
CHARACTERIZATION
TECHNOtOGr PRESCREENNO
TREA1ABILITY STUDY SCOPIW
MANAGEMENT DECISION FACTORS:
• Stale and Community Acceptance
• Schedule Constraints
• Additional Data
REMEDY-SCREENING
TREATABIlfTY
STUDIES
REMEDY-SELECTION
TREATABIimr
STUDIES
RD/RA
TREATABILfTY
STUDIES
Figure 3. Flow diagram of the tiered approach.
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sufficiently detailed to allow for the development of cost
estimates with an accuracy of +50 to -30 percent.
Post-ROD test objectives depend on the nature of the
treatability study. If a study is conducted to prequalify
vendors, performance goals will be equivalent to the cleanup
criteria defined in the ROD. Treatability studies conducted
to select the most appropriate technology among those in a
Contingency ROD will also have performance goals equiva-
lent to the cleanup criteria. Additional test objectives may
include investigation of materials-handling methods, con-
firmation of field-screening analytical techniques, and gen-
eration of detailed cost data. If an RD/RA treatability study
is required to support the detailed design specifications, the
designer will be responsible for defining the test objectives
and performance goals. Test objectives will be focused on
obtaining specific design data, optimizing performance,
and minimizing cost. Treatment train issues such as unit
sizing, materials handling, and systems integration can also
be addressed through specific test objectives. A treatability
study of an entire train can provide data to confirm compli-
ance with ARARs and the cleanup criteria outlined in the
ROD.
2.5 Special Issues
2.5.1 Innovative Treatment
Technologies
One of the advantages of treatability testing is that it per-
mits the collection of performance data on innovative treat-
ment technologies. These newly developed technologies
often lack sufficient full-scale application to be routinely
considered for site remediation. Nevertheless, Guidance
for Increasing the Application of Innovative Treatment
Technologies for Contaminated Soil and Ground Water
(EPA 199la) states:
"Innovative treatment technologies are to be rou-
tinely considered as an option in feasibility stud-
ies for remedial sites and engineering evaluations
for removals in the Superfund program, where
treatment is appropriate commensurate with the
National Contingency Plan (NCP) expectations....
Innovative technologies considered in the remedy
selection process for Superfund, RCRA, and UST
should not be eliminated solely on the grounds
that an absence of full-scale experience or
treatability study data makes their operational
performance and cost less certain than other forms
of remediation.
"When assessing innovative technologies, it is
important to fully account for their benefits. De-
spite the fact that their costs may be greater than
conventional options, innovative technologies may
be found to be cost-effective, after accounting for
such factors as increased protection, superior per-
formance, and greater community acceptance. In
addition, experience gained from the application
of these solutions will help realize their potential
benefits at other sites with similar contaminants."
Example 1 illustrates how treatability studies can be used to
investigate innovative and conventional technologies con-
currently on a single waste stream. Three innovative treat-
ment technologies-thermal desorpiion, solvent extraction,
and bioremediation-are investigated at various tiers. Deci-
sions on testing are based on existing data in the literature
and on prior trcatability study results. Solidification/stabi-
lization, a conventional option, is also tested because its
performance for the particular waste stream was not estab-
lished in the literature. This example reflects how treatability
studies can be designed and tailored by the project manager
to provide specific pieces of information required for rem-
edy selection.
2.5.2 Treatment Trains
Treatment of a waste stream often results in residuals that
require further treatment to reduce toxicity, mobility, or
volume. Treatment technologies operated in scries (treat-
ment trains) can be used to provide complete treatment of a
waste stream and any resulting residuals.
Treatment-train requirements for a waste stream may be
evaluated by applying the tiered approach. Example 2
outlines a remedy-selection treatability study of a treatment
train consisting of low-temperature volatilization followed
by chemical treatment and solidification. The literature
contains enough data concerning the individual unit opera-
tions to indicate that they arc appropriate technologies for
the specific contaminants. Trcatability testing of these unit
operations as a treatment train, however, is necessary to
evaluate the most effective combination of operating pa-
rameters for treating the matrix.
2.5.3 In Situ Treatment Technologies
Testing of in situ treatment technologies during the RI/FS
may entail remedy screening, bench-scale remedy-selec-
tion testing, and pilot-scale remedy-selection testing in the
field. Remedy screening of in situ treatment technologies
is conducted in the laboratory to determine process feasi-
bility. Bench-scale testing is generally conducted in soil
columns designed to simulate the subsurface environment.
Field testing, however, is important for an adequate cvalua-
15
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EXAMPLE 1. TREATABILITY STUDIES OF MULTIPLE TECHNOLOGIES
Old Petroleum Refinery Site
Background
An old petroleum refinery site contained oily sludges and contaminated soils. The primary contami-
nants of concern were polynuclear aromatic hydrocarbons (PAHs), mainly benzo(a)pyrene. The
literature survey identified five potentially applicable technologies for treating the hydrocarbon
wastes: 1) incineration, 2) stabilization/solidification, 3) thermal desorption, 4) solvent extraction,
and 5) bioremediation.
The literature survey also produced a significant amount of performance data for incineration and
bioremediation. Because these data indicated that both technologies were valid for the types of
wastes and contaminants of concern at the site, neither incineration nor bioremediation was evalu-
ated at the remedy-screening tier.
Conversely, little data were found on thermal desorption, and the available performance data for
solvent extraction and stabilization/solidification were inconclusive for hydrocarbon wastes. There-
fore, these three technologies were evaluated at the remedy-screening tier to determine their
feasibility for treatment of the site's wastes.
Remedy Screening
Samples of worst-case soils and sludges (most highly contaminated with PAHs) were collected for
treatability studies of each technology. A performance goal of 90 percent reduction in the indicator
contaminant benzo(a)pyrene was set.
Thermal desorption was evaluated at three temperatures. Solvent extraction was evaluated by
using three solvents at two solution concentrations. Stabilization/solidification was evaluated by
using organophilic clays at three mix ratios with 28-day curing. Benzo(a)pyrene concentration in
duplicate samples of the untreated soil was determined by total waste analysis (EPA SW-846
Method 8270). Duplicate samples of the treated material from thermal desorption, solvent extrac-
tion, and stabilization/solidification (after sonication of the solidified monolith) were then analyzed
for benzo(a)pyrene by the same method.
The results of the remedy screening showed that, of the three technologies, thermal desorption
achieved the highest percentage removal of the indicator contaminant (greater than 95 percent).
Solvent extraction showed a 90 percent removal efficiency. Stabilization/solidification, however,
fixed only 50 percent of the contaminant. Thermal desorption and solvent extraction were thus
retained for further analysis because both technologies achieved the screening performance goal.
Remedy-Selection Testing
Quantitative performance, implementability, and cost issues still remained unanswered after the
remedy screening. Also, information from the literature on biodegradation rates and mechanisms
for benzo(a)pyrene (the principal PAH of concern) was inconclusive. In addition, the anticipated
cleanup criterion for benzo(a)pyrene in soils was very low (250 ppb). Therefore, thermal desorp-
tion, solvent extraction, and bioremediation were examined in bench-scale, remedy-selection
testing. Performance goals were set at 250 ppb benzo(a)pyrene with a 95 percent data confidence
level. Waste samples representing average and worst-case scenarios were tested, triplicate test
samples were collected and analyzed, and several process variables were evaluated. After 6
months of testing, only low-temperature thermal treatment was found to meet the low cleanup levels
required for benzo(a)pyrene.
Although thermal desorption was found to meet the cleanup requirements in bench-scale testing,
this technology had not been previously demonstrated at full scale for similar contaminants and
waste. Therefore, cost and design issues had to be addressed as part of the detailed analysis of
alternatives. The RPM decided to conduct pilot-scale testing on thermal desorption and to compare
the costs of constructing and operating the unit with those for incineration.
16
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EXAMPLE 2. TREATABILITY STUDIES FOR TREATMENT TRAINS
Former Chemical Manufacturing Company
Background
At a former chemical manufacturing company and current Superfund site, the contaminants of
concern in the soils were dichloromethane, tetrachloroethene, benzene, polynuclear aromatic hydro-
carbons (PAHs), cyanide, and arsenic. The cleanup criterion for each of these compounds had been
identified. Both onsite treatment and offsite incineration were being considered as options for site
remediation.
Remedy-Selection Testing
Remedy-selection testing of a treatment train to treat the contaminated soils on site was designed to
include the following unit operations: 1) thermal desorption, 2) chemical treatment, and 3) stabiliza-
tion/solidification. A schematic of the treatment train is presented below.
CONTAMINANTS OF CONCERN
ORGAN ICS
ARSENIC
STABILIZATION/
SOLIDIFICATION
Schematic Representation of the Treatment Train
Bench-scale treatability testing of the treatment train was designed to meet the following three
objectives:
• Objective 1 - Provide performance confirmation of the operation of the thermal desorption unit for
removal of volatile and semivolatile organics. Determine the minimum operating conditions
(temperature, residence time) necessary to achieve the site cleanup criteria. Determine the need
for subsequent treatment units (chemical treatment, solidification).
• Objective 2 - Provide performance confirmation of the operation of the chemical treatment unit for
destruction of cyanide. Determine the preferred reagent and dosage necessary to achieve the
site cleanup criteria.
• Objective 3 - Provide performance confirmation of the operation of the stabilization/solidification
unit for immobilization of arsenic. Determine the preferred binder and dosage necessary to
achieve the site cleanup criteria.
Prior to initiating any treatability tests, the test plan called for the soil to be characterized for the
following physical and chemical parameters:
• Moisture content
• Soil bulk density
• Grain size distribution
• Volatile and semivolatile organics
• Cyanide
• Arsenic (total and TCLP)
The remedy-selection testing consisted of the following three subtasks:
1) Perform bench-scale tests of thermal desorption at two temperatures (300 and 550°C) and three
residence times (5,15, and 30 minutes) to determine the efficacy of the unit for removal of
17
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Example 2 (continued)
organics. Analyze the treated soil for the pollutants of concern (organics, cyanide, and arsenic).
If cyanide is present in the soil residue at concentrations exceeding the cleanup criterion, con-
tinue with Subtask 2. Similarly, if arsenic is present, continue with Subtask 3. (This subtask
addresses Objective 1.)
2) Perform bench-scale tests on the soil residue from the thermal desorption unit to investigate the
effectiveness of hydrogen peroxide and hypochlorite for treatment of cyanide as a function of pH,
the strength of solution, and the reagent-to-soil ratio. Analyze the treated soil for cyanide. (This
subtask addresses Objective 2.)
3) Perform bench-scale tests of stabilization/solidification to immobilize arsenic in the soil residue
from chemical treatment (if cyanide was present) or thermal desorption (if cyanide was not
present) using three binders (portland cement, lime/fly ash, and fly ash/kiln dust) at two binder-to-
soil ratios (0.20 and 0.50). Determine the unconfined compressive strength of the solid monolith.
Extract the crushed solid in accordance with the toxicity characteristic leaching procedure and
analyze the leachate for arsenic. (This subtask addresses Objective 3.)
Data from the remedy-selection treatability tests were used 1) to determine if the proposed treatment
train could achieve the test objective of reducing all contaminant concentrations to the site cleanup
criteria, and 2) to provide a preliminary basis for estimating the costs of full-scale remediation.
tion of in situ treatment. Because of the unique difficulties
associated with simulating in situ conditions and monitor-
ing the effectiveness of in situ treatment in the laboratory,
field testing often may be the only way to obtain the critical
information needed for the detailed analysis of alternatives
during the FS. Example 3 demonstrates how the tiered
approach may be applied to evaluate in situ soil Hushing.
2.5.4 Generic Vs. Vendor Treatability
Studies
When planning a treatability study, the project manager
must determine whether results from treatability tests in
which widely available chemicals and processes are used
("generic" studies) will be as useful as vendor-conducted
tests involving the use of proprietary chemical reagents and
treatment systems ("vendor" studies).
Because generic ireatability studies eliminate the need for
establishing contracts and schedules with a specific vendor,
they can often be performed quickly and inexpensively;
however, they may not always provide an adequate evalua-
tion of a technology. For example, a generic treatability
study may fail to meet site cleanup goals that could have
been achieved by an experienced technology vendor using
proprietary processes and equipment developed through
years of research.
Generally, remedy-screening treatability studies can be per-
formed generically because quantitative performance data
are not required. Vendor-specific equipment or experience
are often required, however, at the remedy-selection tier to
assure the generation of high-quality quantitative data and
the best performance of the technology. Remedial design/
remedial action treatability studies should generally be per-
formed in consultation with technology vendors. Tables 2
and 3 were adapted from tables developed by personnel at
the U.S. EPA's Risk Reduction Engineering Laboratory
(RREL) to provide general technology-specific guidance
on this issue (dcPcrcin, Bates, and Smith 1991). Informa-
tion in these tables should not be used without consider-
ation being given to site-specific contaminant and matrix
treatability data.
Under 48 CFR Section 1536.209 of the Federal Acquisition
Regulations, subcontractors performing ircatability studies
in support of remedy selection or remedy design are not
prohibited from being awarded a contract on the construc-
tion of the remedy (55 FR 49283). For prime contractors
performing treatability studies, however, approval by the
Responsible Associate Director in the EPA Procurement
and Contracts Management Division may be necessary
before they can be awarded the construction contract. In
reviewing requests for approval, EPA will take into ac-
count its policy of promoting the use of innovative tech-
nologies in the Supcrfund program.
2.5.5 PRP-led Pre-ROD Treatability
Studies
Prc-ROD trcatability studies may be conducted by poten-
tially responsible parties with EPA oversight to evaluate
PRP-proposcd alternatives at enforcement-led sites. The
steps involved in a PRP-lcd study include performing a
18
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EXAMPLE 3. TREATABILITY STUDIES FOR IN SITU TREATMENT TECHNOLOGIES
In Situ Soil Flushing
Background
An estimated 80,000 cubic meters of soil contaminated with chlorinated phenols, semivolatile organ-
ics, sulfur-containing compounds, and lead at an industrial facility requires corrective action. In situ
soil flushing has been proposed as an alternative treatment technology. A two-tiered treatability study
has been designed to evaluate its effectiveness.
Remedy Screening
Remedy screening will be performed to evaluate the effectiveness of various flushing reagents for
enhancing the removal of the contaminants. A performance objective of 90 percent or greater
reduction was set for evaluation of flushing reagent feasibility. Any reagent that achieves this level of
contaminant reduction for each target contaminant will be evaluated at the remedy-selection tier. All
others will be screened out. (Analyses of all samples for all site-specific contaminants will not be
economically feasible: therefore, target compounds, each representative of a class of compounds
present at the site, will be identified.)
The following general testing procedure will be used:
1) Analyze untreated soil samples for target compounds.
2) Place a known mass of soil in a small glass bottle. Add a measured volume of flushing reagent.
Shake for a set period of hours. Centrifuge the mixture.
3) Analyze the supernatant liquid phase for target contaminants.
4) Analyze the treated soil phase for target contaminants.
Remedy-Selection Testing
Bench Scale
All flushing reagents identified as feasible during the remedy-screening treatability study will be
evaluated in a bench-scale column test. The performance objective of this tier is to achieve contami-
nant reduction levels equal to the anticipated site cleanup criteria.
The following general testing procedure will be used:
1) Analyze untreated soil samples for target compounds.
2) Pack a large glass column with untreated soil to approximate the actual density of soil in the
contaminated area. Introduce the soil-flushing solution into the top of the column.
3) Collect the column leachate at regular intervals (e.g., daily) and analyze for target contaminants.
4) Terminate the column test when the contaminant concentrations in the leachate remain the same
for three consecutive leaching periods. Remove representative samples of the treated soil from
the glass column and analyze them for target contaminants.
All flushing reagents that reduce the target contaminant concentrations in the soil to the site cleanup
levels will be evaluated in the field.
Pilot Scale
The twofold purpose of this field pilot-scale treatability study is to evaluate the hydraulics of the
treatment process under site conditions and to verify reagent performance under site conditions. The
field test will yield site-specific flow, injection, and capture rates for the flushing system. These rates
must be established to quantify the total time necessary for site-wide treatment and to estimate full-
scale treatment costs. These and other data will be used in the detailed analysis of alternatives.
The field treatability study will involve the following tasks:
1) Prepare a treatment cell. Install an interception trench.
2) Install the irrigation and soil-flushing system.
3) Collect the cell leachate at regular intervals and analyze for all contaminants of interest.
4) Terminate the field test when the target contaminant concentrations in the leachate remain the
same for three consecutive leaching periods. Remove representative samples of the treated soil
from the cell and analyze them for all contaminants of interest.
19
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Table 2. Aqueous Field Treatability Studies:
Generic Versus Vendor Processes8
Treatment technology
Physical
Oil/water separation
Sedimentation
Filtration
Solvent extraction
Distillation
Air/steam stripping
Carbon adsorption
Ion exchange
Reverse osmosis
Ultra filtration
Chemical
Neutralization
Precipitation
Oxidation
Reduction
Dehalogenation
Thermal
Incineration
Biological
Suspended growth
systems
Aerobic
Anaerobic
Fixed growth systems
Aerobic
Anaerobic
Constructed wetlands
Pact
In situ biological
Remedy
screening
NA
NA
NA
G
G
G
G
G
G
G
NA
G
G
G
G
G
G
G
G
G
G
G
NA
Remedy
selection
G
G
G
G/V
G
G
G
G
G/V
V
G
G
G
G
G/V
G/V
G
G
G/V
G/V
G
G/V
G
RD/RA
G
G
G
G/V
G/V
G/V
G
G/V
V
V
G
G
G
G
V
V
G
G/V
G/V
G/V
G
V
V
aG = Generic studies appropriate.
V = Vendor studies appropriate.
G/V = Generic and vendor studies appropriate.
NA = Not applicable at this tier.
literature search, submitting the Technical Memorandum
identifying candidate technologies, designing ihe study,
preparing the Project Plans (Work Plan, Sampling and
Analysis Plan, and Health and Safety Plan), performing the
test, analyzing the data, and preparing a final report on the
results.
During the study, the EPA project manager will provide
oversight and assistance. The EPA's Guidance on Over-
sight of Potentially Responsible Party Remedial Investiga-
tions and Feasibility Studies (EPA 1991b) recommends
that the EPA project manager and the oversight assistant
perform the following activities to oversee PRPs:
• Provide ihe PRPs with relevant guidance documents
and sources of other technical information (Appendix
A presents sources of ireatability information).
• Review and approve the Technical Memorandum pre-
pared by the PRP thai identifies candidate treatment
technologies and describes the literature search.
• Meet with the oversight assistant, the Technical Sup-
port Team (TST), and representatives from ORD to
review the list of candidate technologies. Innovative
treatment technologies should be adequately repre-
sented. Decisions on ihc need for ireatability studies
should be made for each technology.
• Review and approve the PRP's schedule of trcaiabiliiy
activities.
Table 3. Soils/Sludges Field Treatability Studies:
Generic Versus Vendor Processes8
Remedy
Treatment technology screening
Physical
Oil/water separation G
Sedimentation G
Filtration G
Solvent extraction G/V
Soil washing G
Vacuum extraction G
Distillation G
Air/steam stripping G
Thermal stripping G
Carbon adsorption G
Ion exchange G/V
Chemical
Neutralization G
Precipitation G
UV photolysis G
Ozonation G
Oxidation G
Reduction G
Dehalogenation G/V
Thermal
Incineration G
Biological
In situ treatment G
Composting G/V
Stabilization
Pozzolanic for G
inorganics
Pozzolanic for organics V
Asphalt G
Polymerization V
Vitrification G/V
Material handling
Screening NA
Conveying NA
Remedy
selection
G
G
G
V
G/V
V
G
G/V
V
G/V
V
G
G/V
V
G/V
V
V
V
G/V
G
G/V
G/V
V
V
V
V
G
G
RD/RA
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
G/V
V
V
V
V
V
G/V
G/V
aQ = Generic studies appropriate.
V a Vendor studies appropriate.
G/V a Generic and vendor studies appropriate.
NA - Not applicable at this tier.
20
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• Revise and amend the original PRP Project Plans to
address the treatability study work to be performed.
• Verify the qualifications of all personnel involved in
the test, including the PRP, the PRP's contractor, and
the analytical laboratory. In addition, the EPA project
manager should verify that the PRP laboratory proto-
cols conform to EPA standards.
• Verify the test objectives and performance goals of
each study.
• Conduct a site visit during the initial stages of a study.
• Collect and analyze split samples before and after
treatment
• Review and validate the data generated by each study.
• Monitor compliance with ARARs.
• Review and approve the draft PRP Treatability Study
Evaluation Report with input and comments from the
1ST, ORD, other support staff, and the State. (The
report should be prepared in the standard format pre-
sented in Subsection 3.12.)
• Continually update the Administrative Record File and
cost recovery documentation.
Conduct of PRP-led treatability studies will be based on the
language of the Administrative Order on Consent (AOC)
and the Statement of Work (SOW). The model Adminis-
trative Order on Consent for Remedial Investigation/Fea-
sibility Study (EPA 1991c) contains standard language for
requiring PRPs to conduct treatabilily studies. The Model
Statement of Work for a Remedial Investigation and Feasi-
bility Study Conducted by Potentially Responsible Parties
(EPA 1989c) provides standard language for requiring PRPs
to perform treatability studies in accordance with the RI/FS
guidance. (Note: The Model SOW docs not yet incorpo-
rate the treatability study terminology and guidance pre-
sented in this document. Until the Model SOW is updated,
every effort should be made to require PRPs to conduct
treatability studies in accordance with this guidance.)
2.5.5 Treatability Study Funding
The planning process for treatabilily studies should begin
during the budget cycle in the year prior to the planned
performance. The potential need for and scope of treatability
studies should be identified and their costs estimated to
ensure that adequate resources will be available. This
information will be used to prepare the Region's Superfund
Comprehensive Accomplishments Plan (SCAP).
Federally funded treatabilily studies performed in support
of the RI/FS or the RD/RA are funded as a line item in the
Region's "Other Remedial Account." Should treatabiliiy
study funding requirements exceed planned allocations (be-
cause of the cost of the studies or the need for studies that
were not planned for in the SCAP), the SCAP should be
updated to reflect the necessary additional funding.
Funding for treatability studies is currently separate from
RI/FS funding and is not included in the RI/FS target cost
of 5750,000. The Agency is considering a revision of this
procedure based on the need to fund direct site work through
a Site-Specific Allowance. This will facilitate efficient
tracking of direct site costs.
21
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SECTION 3
PROTOCOL FOR CONDUCTING TREATABILITY STUDIES
3.1 Introduction
Treatabilily studies should be performed in a systematic
fashion to ensure that the data generated can support rem-
edy selection and implementation. This section describes a
general protocol for conducting treatability studies that
EPA project managers, PRPs, and contractors should fol-
low. The protocol includes:
• Establishing data quality objectives
• Identifying sources for treatability studies
• Issuing the Work Assignment
• Preparing the Work Plan
• Preparing the Sampling and Analysis Plan
• Preparing the Health and Safety Plan
• Conducting community relations activities
• Complying with regulatory requirements
• Executing the study
• Analyzing and interpreting the data
• Reporting the results
These elements are described in detail in the remaining
subsections. General information applicable to all
treatability studies is presented first, followed by informa-
tion specific to remedy screening, remedy-selection test-
ing, and RD/RA testing.
Pre-ROD treatability studies for a particular site will often
entail multiple tiers of testing, as described earlier in Sub-
section 2.3. Duplication of effort can be avoided by recog-
nizing this possibility in the early planning stages of the
project. The Work Assignment, Work Plan, and other
supporting documents should include all expected activities.
Generally, a single contractor should be retained to ensure
continuity of the project as it moves from one tier to another.
3.2 Establishing Data Quality
Objectives
Data quality objectives (DQOs) arc qualitative and quanti-
tative statements that specify the quality of the data required
to support decisions concerning remedy selection and imple-
mentation. The end use of the ircatability study data to be
collected will determine the appropriate DQOs. At all tiers of
trcatability testing, the establishment of DQOs will help to
ensure that the data collected arc of sufficient quality to
substantiate the decision. Established DQOs are incorporated
into the Work Plan, the study design, and the Sampling and
Analysis Plan (SAP). Because ircatabilily testing is used to
help select and implement a site remedy, establishing DQOs
is a critical initial step in the planning of ircatability studies.
The quality and quantity of treatability data required for a
study should correspond to the significance and ramifica-
tions of the decisions that will be based on these data.
Limited QA/QC is generally required for remedy-screen-
ing data used to decide whether a treatment process is
potentially feasible and warrants further consideration. More
rigorous QA/QC is required for remedy-selection testing
data used to determine whether a technology can meet the
expected cleanup criteria or to compare the costs of several
treatment alternatives, as these data have a greater impact
on the decisions required for technology selection. Rigor-
ous QA/QC is also required for RD/RA testing when quan-
titative performance, design, and cost data will be used in
the implementation of the selected remedy.
3.2.7 General
The guidance document Data Quality Objectives for Reme-
dial Response Activities (EPA I987a) defines the framc-
23
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work and process by which DQOs are developed. This
document (hereinafter referred to as the DQO guidance)
focuses on site investigations during the RI/FS; however,
the same framework and process may be applied to DQO
development for treatability studies. The DQO guidance
describes a process that includes the following three stages:
1) identification of decision types and study objectives, 2)
identification of data uses/needs, and 3) design of the data-
collection program. The three stages of DQO development
summarized in Table 4 can be applied to each of the three
tiers of testing. The stages provide a systematic process for
development of the DQOs for treatability studies.
Stage 1
The type and magnitude of the decisions to be made are
determined in Stage 1. Tasks include identifying the data
users and coordinating their efforts for the establishment of
the DQOs, evaluating existing data, developing a concep-
tual model, and specifying the test objectives (including
performance goals) of the treatability study. Stage 1 efforts
should result in the specification of the decision-making
process and the identification of any new data needed and
why. Stage 1 of the DQO process corresponds to technol-
ogy prescreening and treatability study scoping as described
in Subsection 2.2.1.
The data users will be those who rely on treatability results
to support their decisions. They may include the RPM, the
OSC, the PRP project manager, technical specialists, the
State, enforcement personnel, U.S. Army Corps of Engi-
neers, and others. Project review and audit personnel should
be involved to help ensure the integrity of the QA program
and compliance with program policy.
Stage 1 also includes a detailed evaluation of available
information. Useful information may include site charac-
terization data, technology-specific information, and previ-
ous treatability study data. Several factors should be con-
sidered in an evaluation of the quality of these data and
their relevance to the DQO establishment process, includ-
ing the age of the data, the analytical methods used, the
detection limits of those methods, and the QA/QC proce-
dures applied.
A conceptual model of the site and site conditions should
be developed and included in Stage 1. A model may
already have been developed for the site; if so, it should be
adopted for use in the treatability study DQO development
process.
Test objectives for the treatabilily study are determined in
Stage 1. Identifying these objectives also entails identify-
ing the problems to be solved (i.e., whether the study is
needed to determine the potential feasibility of the technol-
ogy or to confirm the attainment of a treatment standard).
Test objectives will include achieving quantitative perfor-
mance goals and collecting data to support qualitative engi-
neering assessments and cost estimates.
Stage 2
During Stage 2, the data required to meet the test objectives
specified in Stage 1 are determined, and the criteria for
Table 4. Summary of Three-Stage DQO Development Process
Stage 1
Identify data users.
Consult appropriate data bases for relevant information.
Develop a conceptual model of the site.
Identify the treatability study test objectives and performance goals.
Stage 2
Identify data uses.
Identify data types.
Identify data quality needs.
Identify data quantity needs.
Evaluate sampling and analysis options.
Review precision, accuracy, representativeness, completeness, and comparability
parameters.
Stage 3
Determine DQOs; select methods for obtaining data of acceptable quality and quantity.
Incorporate DQOs into the Work Plan and the SAP.
24
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determining data adequacy are stipulated. Data must be of
sufficient quality to determine whether the test objectives
have been met.
Data types are identified by broad categories such as envi-
ronmental media samples or source samples. Specifying
data type by medium helps to identify overlapping data
needs and analytical efforts.
Data quality and quantity are defined in Stage 2. The
EPA's Quality Assurance Procedures for RREL (EPA
1989d) establish four quality assurance categories for use
in research and development projects. Categories IV, III,
and II are applicable to trcatability studies. In general, QA
Category IV applies to remedy-screening treaiabilily stud-
ies, and QA Categories III and II apply to both remedy-
selection and RD/RA treatability studies. In determining
the appropriate QA category, the decision maker must
consider the intended use of the data and the risks associ-
ated with selecting an ineffective remedy based on the
quality and quantity of the treatability data collected.
When the data quality needs for a project have been de-
fined, confidence limits can be established for the data to be
generated. Specific confidence limits have not been estab-
lished for each treatability study tier. Rather, the intended
use of the data and the limitations and costs of various
analytical methods will assist the decision maker in defin-
ing appropriate confidence limits for the tier of testing
being planned. Sampling and analysis options are re-
viewed in Stage 2 of the DQO development process. Issues
to be considered during the review process include the data
uses; data types; data quality needs; data quantity needs;
precision, accuracy, representativeness, completeness, and
comparability (PARCC) parameters (Table 5); analytical
costs; and the time required for analysis.
The PARCC parameters arc defined by the intended use of
the data and are indicative of data quality. As the data
quality and quantity needs increase, the PARCC parameter
goals must rise. It is not practical to set universal PARCC
goals for instability testing because of the variability in
sites, technologies, and contaminants.
Stage 3
Methods for obtaining data of acceptable quality and quan-
tity are chosen and incorporated into the project Work Plan
and SAP during Stage 3. The purpose of Stage 3 is to
assemble the data collection components into a compre-
hensive data collection program. As data quality needs
increase, the need for detailed goals and documentation
components in the collection program will increase.
3.2.2 Remedy Screening
The DQOs established for remedy screening are usually
stated in qualitative terms. Remedy screening provides a
qualitative engineering assessment of the potential feasi-
bility of a technology (i.e., go/no go). Therefore, QA
Category IV usually provides data of sufficient quality for
remedy screening. According to Quality Assurance Proce-
dures for RREL, QA Category IV is designed to support
basic research that may change direction several times in
Table 5. PARCC Parameters
Precision
Accuracy
Representativeness
Completeness
Comparability
A quantitative measure of the variability of a group of measurements, normally
stated in terms of standard deviation, range, or relative percent difference.
Precision is determined from analytical laboratory replicates (split samples) and
test replicates (collocated samples).
A quantitative measure of the bias in a measurement system, normally stated
in terms of percent recovery. Accuracy is determined by QC samples and
matrix spikes with known concentrations.
A qualitative statement regarding the degree to which data accurately and
precisely represent a population or condition. Representativeness is addressed
by ensuring that sampling locations are selected properly and that a sufficient
number of samples are collected.
The percentage of the measurements that are judged to be valid. Regardless
of the use of the data, a sufficient amount of the data generated should be
valid.
A qualitative statement regarding the confidence with which one data set can
be compared with another. Comparability is achieved through the use of
standard techniques to collect and analyze samples and to report results.
25
-------
the course of testing. The PARCC requirements are therefore
broadly defined in this category to permit flexibility during
the actual testing. Confidence limits established for data
derived from remedy screening are typically wide, in keeping
with the characteristics of this tier (i.e., low cost, quick
turnaround, and limited QA/QC). A minimum number of
QC checks are required to assess accuracy and precision.
Remedy screening does not require a significant amount of
replication in the test samples and the analytical tests
performed. The need for accuracy checks such as matrix
spikes and blanks is also limited.
5.2.3 Remedy-Selection Testing
For remedy selection, DQOs are primarily quantitative in
nature. For example, a performance goal for remedy-
selection testing involving solvent extraction and chemical
dehalogenation may be to reduce polychlorinated biphe-
nyls (PCBs) to less than 30 ppm in soils (the target cleanup
goal specified for the site). The data required to meet this
quantitative goal are derived from detailed waste character-
ization and performance testing. These data will be used to
select one of the technologies in the ROD.
Because data used in support of remedy selection must
have a high level of confidence, QA Categories III or II
are recommended for remedy-selection testing. These
categories are designed to support the evaluation and
selection of technologies. The PARCC parameters are
therefore narrowly defined and test data are well docu-
mented. The selection of Category III (less stringent) or
Category II (more stringent) for treatability testing de-
pends on the intended use of the data and on time and cost
constraints.
Narrow confidence limits are typically required at this tier.
Quality control checks for accuracy and precision will be
more thorough than for remedy screening. A significant
amount of test sample and analytical sample replication
will be required to determine accuracy and precision pa-
rameters. The representativeness of the data must be care-
fully documented, and a sufficient amount of the data
generated should be judged valid. Standard sampling and
analysis techniques should be used whenever possible to
assure data comparability. The testing apparatus should be
designed to generate enough treated material to support this
QA program.
The need for detailed analyses and high-quality data at the
remedy-selection tier will result in significantly higher ana-
lytical costs and longer turnaround times compared with
those for remedy screening. These factors must be consid-
ered when establishing DQOs for remedy-selection
treatability studies.
3.2.4 RD/RA Testing
The principal objective of RD/RA testing is to obtain quan-
titative performance, design, and cost data for use in the
implementation of the selected remedial technology. Data
quality objectives for RD/RA trcatabilily studies are there-
fore primarily quantitative.
The need for design, cost, and performance information
will dictate the frequency of sampling and testing, the
required confidence limits, and the level of QA/QC. The
uses for RD/RA treatability study data differ from those for
remedy-selection data, but the required level of data quality
will be the same or less. Therefore, QA Categories III or II
are recommended for RD/RA testing.
In general, RD/RA testing will involve significant replica-
tion in test sampling (collocated samples) and laboratory
analyses (split samples). Typically, PARCC parameters
are narrowly defined and test data arc well documented.
Confidence limits will be similar to those for remedy-
selection testing.
3.3 Identifying Sources for Treatability
Studies
3.3.1 General
Once the decision to conduct a trcatability study has been
made and the scope of the project has been defined, the
project manager must identify a qualified program contrac-
tor or technology vendor with the requisite technical capa-
bilities and experience to perform the work. Treatability
studies can be performed in house or via several contract
mechanisms that exist for the remedial and removal pro-
grams under CERCLA.
In-house Capabilities
In support of Superfund, EPA has created several programs
and documents to assist EPA site managers in the perfor-
mance of treatability studies. These include the Superfund
Technical Assistance Response Team (START), the RREL
Remedy-Screening Treatability Study Laboratory, the En-
vironmental Response Team (ERT), and the Inventory of
Treatability Study Vendors.
Superfund Technical Assistance Response Team. Site-
specific, long-term assistance is available to project man-
agers through START. Sponsored by ORD-RREL, the
START program provides comprehensive engineering as-
sistance from early RI/FS scoping through RA implemen-
tation at a limited number of sites. Sites arc chosen by the
26
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Regions for START support because of their complex con-
taminants and matrices.
Treatability support services available to project managers
through START include:
• Identification of potentially applicable technology op-
tions
• Determination of need for treatability studies
• Performance of remedy-screening treatabilily studies
• Review of treatability study Project Plans
• Oversight of PRP-conducted treatability studies
• Review of PRP deliverables and final reports
Treatability support through the START program can be
obtained by contacting the RREL Technical Support Branch
in Cincinnati, Ohio.
RREL Remedy-Screening Treatability Study Laboratory.
The RREL has developed a series of remedy-screening
treatability tests. These protocols are designed to provide
the Regions with inexpensive, preliminary assessments of
the potential feasibility of a given technology for remediating
contaminated soil. In-house testing can be performed for:
• Soil vapor extraction
• Solvent extraction
• Soil washing
• Soil flushing
• Biological degradation
• Chemical dehalogenation
• Solidification/stabilization
• Thermal desorption
• Incineration technologies
Regions can have these tests performed by contacting the
RREL Technical Support Branch in Cincinnati, Ohio (see
Appendix A).
Environmental Response Team. Serving as the EPA's in-
house consultants on Supcrfund issues and oil spills, the
Environmental Response Team provides technical sup-
port to OSCs and RPMs for both emergency removal and
long-term remedial actions. With support from the Re-
sponse Engineering and Analytical Contractor, the ERT's
Alternative Technology Section can design and perform
remedy-screening and remedy-selection treatability stud-
ies for a wide range of technologies. The Section can
provide testing oversight and evaluate and interpret
treatabilily test results. Regions can request treatability
study support by contacting the ERT in Edison, New
Jersey (see Appendix A).
Inventory of Treatability Study Vendors. The ORD has
compiled a list of vendors and contractors who have ex-
pressed an interest in performing treatability studies. This
document, entitled Inventory of Treatability Study Ven-
dors. Volumes I and I! (EPA 1990a), was compiled from
information received from contractor/vendor responses to a
published request. It lists commercial firms that offer
treatability study services and describes their capabilities.
(This information has not been verified by EPA.) The
inventory is sorted by treatment technology, contaminant
group, and company name. It can be searched electroni-
cally by contacting the EPA Alternative Treatment Tech-
nology Information Center (ATTIC) (see Appendix A).
Figure 4, an example page from the document, shows the
types of information the inventory contains.
Contractors or Vendors
Three available methods for obtaining trcaiability study
services from contractors arc discussed here.
ARCS, ERCS, and TAT Contracts. Alternative Remedial
Contracts Strategy (ARCS) contracts are used to obtain the
program management and technical services needed to sup-
port remedial response activities at CERCLA sites. To
retain a treatability study vendor through this contract
mechanism, the EPA project manager (in conjunction with
the EPA contract officer) must issue to the prime contrac-
tor a Work Assignment outlining the required tasks. The
prime contractor may elect to perform this work or to
assign it to one of its subcontractors. Emergency Response
Cleanup Services (ERCS) and Technical Assistance Team
(TAT) contracts provide similar support services at
CERCLA removal sites. Both ERCS and TAT contractors
can be directed to perform trcatability studies.
Technical Assistance and Support Contracts. When a spe-
cific waste at a particular site requires the specialized ser-
vices of a contractor that can treat that waste (e.g., a mixed
radioactive/hazardous waste) and such services arc not avail-
able from firms accessible through existing contracts, the
EPA project manager may need to investigate which firms
27
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TREATABILITY STUDY VENDORS BY COMPANY NAME
COMPANY:
Address:
City:
Contact:
Treatment Technology: ACTIVATED CARBON
Other Treatment Capability: S TECHNOLOGIES
CURREMT AVAILABLE FACILITY: LABORATORY
Permitting Status: EPA 10 AS SMALL GENERATOR
Mobile Facility? YES
Bench Scale? YES
Unit Capacity: INFORMATION NOT PROVIDED
Price Information: INFORMATION NOT PROVIDED
Media Treated: 1. AQUEOUS MEDIA
3.
5.
Contaminant 1. HALOCENATED NONVOLATILES
Group! 3. NONMALOGENATEO NONVOLATILES
Treated: 5. NONVOLATILE METALS
7. ORGANIC CYANIDES
9. VOLATILE METALS
11.
Other Contaminant Groups That Can Be Treated:
Experience at Stperfind Sites?
SUPERFUNO SITE * 1: A I F MATERIAL RECLAIMING
Site Location: GREENVILLE
Start Date: 00/84
Unit Utilized for/at Site: INFORMATION NOT PROVIDED
Price Infometion: INFORMATION NOT PROVIDED
Media Treated 1. AQUEOUS MEDIA
3.
5.
Contaminant 1. VOLATILE METALS
Groups 3.
Treated: 5.
7.
9.
1'-.
Other Contaminant Groups Treated:
SUPERFUNO SITE * Z: AMERICAN CREOSOTE
Location: JACKSON
Start Date: 00/86
Unit Utilized for/at Site: INFORMATION NOT PROVIDED
Price Information: INFORMATION NOT PROVIDED
Media Treated: 1. AQUEOUS MEDIA
3.
S.
Contaminant 1. NONVOLATILE METALS
Groups 3. CREOSOTE
Treated: 5.
7.
9.
11.
Other Contaminant Croups:
Company Type: SMALL BUS
State: Zip:
Phone:
Studies/Month: INP
Fixed Facility? YES
Pilot Scale? NO
Location: ATLANTA. CA
Z. ORGANIC LIQUID
4.
Other:
Z. HALOGENATED VOLATILE*
1. NONHALOGENATED VOLATILES
6. ORGANIC CORROSIVES
8. PCBS
10.
1Z.
NOT SPECIFIED
YES
EPA Region: S ID »: 17
State: IL
End Date: INP
Z.
4.
Other:
Z.
4.
6.
8.
10.
12.
EPA Region: 5 ID »: 7Z
State: TN
End Date: INP
Z.
4.
Other:
Z. PCBs
4.
6.
a.
10.
12.
OTHER ORGANICS
Figure 4. Information contained in the ORD Inventory of Treatability Study Vendors.
28
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with this specialized capability are accessible through other
contracting mechanisms. Access to technical assistance
and support contracts may be available through the RREL,
the U.S. Bureau of Mines, or the U.S. Army Corps of
Engineers.
Request for Proposal. In the absence of an existing con-
tracting mechanism for accessing the required treatability
study services for a specific waste at a particular site, a new
contracting mechanism can be established. This will gen-
erally be the prime mechanism by which PRPs obtain
treatability study services. Obtaining the services of a
specific firm through a new contracting mechanism usually
involves three steps: 1) a request for proposal (RFP), 2) a
bid review and evaluation, and 3) a contract award. (Note:
This can be a time-consuming process.)
An RFP is an invitation to firms to submit proposals to
conduct specific services. It usually contains the following
key sections:
• The type of contract to be awarded (e.g., fixed-price or
cost plus fixed fee)
• Period of performance
• Level of effort
• Type of personnel (levels and skills)
• Project background
• Scope of work
• Technical evaluation criteria
• Instructions for bidders (e.g., due date, formal, as-
sumptions for cost proposals, page limit, and number
of copies)
Appropriate firms listed in ORD's Inventory ofTreatability
Study Vendors should be notified of the RFP in accordance
with the Federal Acquisition Regulations. Proposals sub-
mitted by a fixed due date in response to an RFP go to
several reviewers to determine the abilities of the prospec-
tive firms to conduct the required services. The technical
proposals should be evaluated (scored) with a standard
rating system that is based on the technical evaluation
criteria presented in the RFP. Contract award should be
based on a firm's ability to meet the technical requirements
of the testing involved, its qualifications and experience in
conducting similar studies, the availability and adequacy of
its personnel and equipment resources, and (other things
being equal) a comparison of cost estimates.
3.3.2 Remedy Screening
Remedy screening involves relatively simple tests that re-
quire no special equipment. These studies can often be
performed generically (as discussed in Subsection 2.5.4)
by the RREL; by the ARCS, ERCS, or TAT contractor; or
by the Slate or PRP prime support services contractor.
3.3.3 Remedy-Selection Testing
Remedy-selection testing of proven or demonstrated tech-
nologies can sometimes be performed by the ARCS, ERCS,
or TAT contractor. Tests involving innovative technolo-
gies, however, may require special vendor-specific capa-
bilities that are only accessible through technical assistance
and support contracts or an RFP.
3.3.4 RD/RA Testing
Post-ROD testing entails more complex tests involving the
use of specialized equipment. Because such capabilities
may not be available through any existing contracting
mechanism within the Agency, it may be necessary to issue
an RFP to obtain RD/RA treauibility study services. The
RFP will generally be issued by the designer.
3.4 Issuing the Work Assignment
The Work Assignment is a contractual document that out-
lines the scope of work to be provided by the contractor. It
presents the rationale for conducting the study, identifies
the waste stream and technology(ies) to be tested, and
specifies the tier(s) of testing required. Table 6 presents the
suggested organization of the trcaiability study Work As-
signment.
3.4.7 Background
The background section of the Work Assignment describes
the site, the waste stream, and the treatment technology
under investigation. Site-specific concerns that may affect
waste handling, the experimental design, or data interpreta-
tion, as well as specific process options of interest, should
be duly noted. The results of any previous treatability
studies conducted at the site also should be included.
3.4.2 Test Objectives
This section defines the objectives of the treatability study
and the intended use of the data (i.e., to determine potential
feasibility; to develop performance or cost data for remedy
selection; or to provide detailed design, cost, and perfor-
mance data for remedy implementation). The test objec-
29
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Table 6. Suggested Organization of Treatability
Study Work Assignment
1. Background
1.1 Site description
1.2 Waste stream description
1.3 Treatment technology description
1.4 Previous treatability studies at the site
2. Test Objectives
3. Approach
3.1 Task 1 - Work Plan preparation
3.2 Task 2 - SAP, HSP, and CRP
preparation
3.3 Task 3 - Treatability study execution
3.4 Task 4 - Data analysis and
interpretation
3.5 Task 5 - Report preparation
3.6 Task 6 - Residuals management
4. Reporting Requirements
4.1 Deliverables
4.2 Monthly reports
5. Schedule
6. Level of Effort
lives will include performance goals lhai are based on
established cleanup criteria for the site or, when such crite-
ria do not exist, on contaminant levels that are protective of
human health and the environment. If the treatability study
Work Assignment is issued before site cleanup goals have
-been established, the test objectives should be written with
enough latitude to accommodate changes as the trcatability
testing proceeds without modifying the Work Assignment.
3.4.3 Approach
The approach describes ihe manner in which the treatability
study is to be conducted. It should address the following
six tasks: 1) Work Plan preparation; 2) Sampling and
Analysis Plan (SAP), Health and Safety Plan (HSP), and
Community Relations Plan (CRP) preparation; 3) instability
study execution; 4) data analysis and interpretation; 5)
report preparation; and 6) residuals management.
Task 1 - Work Plan Preparation
This task outlines the elements to be included in the Work
Plan. If a project kickoff meeting is needed to define the
objectives of the treatability study or to review the experi-
mental design, it should be specified here. The contractor
should not begin work on subsequent tasks until receipt of
the project manager's approval of the Work Plan.
Task 2 • SAP. HSP. and CRP Preparation
This task describes activities specifically related to the
treatability study that should be incorporated into the exist-
ing site SAP, HSP, and CRP. Examples of such activities
include field sampling and waste stream characterization,
operation of pilot-plant equipment, and public meetings to
discuss treatability study findings.
Task 3 - Treatability Study Execution
Requirements for executing the treaiabiliiy study are out-
lined in this task. It should include requirements that the
contractor review the literature and site-specific informa-
tion, identify key parameters for investigation, and specify
conditions of the test. This task also should identify guid-
ance documents (such as this guide or other technology-
specific protocols) to be consulted during the planning and
execution of the study.
Task 4 • Data Analysis and Interpretation
This task describes how data from the treaiabiliiy study will
be used in the evaluation of the remedy. If statistical
analysis of the data will be necessary, the requirements
should be stipulated here.
Task J - Report Preparation
This task describes the contents and organization of the
final project report. If multiple tiers of testing arc expected,
an interim report may be requested upon completion of
each tier. The contractor should be required to follow the
reporting format outlined in Subsection 3.12.
Task 6 • Residuals Management
Residuals generated by treatability testing must be man-
aged in an environmentally sound manner. This task should
specify whether project residuals arc to be returned to the
site or shipped to an acceptable ol'fsite facility. In the latter
case, the responsible waste generators (lead agency, PRP,
or contractor) should be clearly identified.
3.4.4 Reporting Requirements
This section identifies the project dcliverablcs and monthly
reporting requirements. Project dcliverablcs include the
Work Plan; the SAP, HSP, and CRP (as appropriate); and
interim and final reports. It should indicate the format
specifications (as outlined in this guidance) and the number
of copies to be delivered. All remedial and removal Work
Assignments must include a requirement for one camera-
ready master copy of the trcatability study report to be
30
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provided to the Office of Research and Development (EPA
1989e) for use in updating the RREL Trcatability Data
Base. (The report should be sent to the address listed in
Subsection 3.12.)
Monthly reports should summarize the progress made in
the current month, projected progress for the coming month,
any problems encpuntered, and expected versus actual costs
incurred.
3.4.5 Schedule
The schedule establishes the timeframe for conducting the
treatability study and includes due dates for submission of
the major project deliverables. Sufficient time should be
allowed for approval of the Work Plan, subcontractors, and
other required administrative approvals; site access and
sampling; analytical turnaround; equipment setup and shake-
down; data analysis and interpretation; and review and
comment on reports.
3.4.5 Level of Effort
The level of effort estimates the number of technical hours
required to complete the project. Special skills or expertise
are required for most treauibility studies, and these require-
ments should be so noted.
3.5 Preparing the Work Plan
Treatability studies must be carefully planned to ensure
that the data generated are useful for evaluating the feasi-
bility or performance of a technology. The Work Plan,
which is prepared by the contractor when the Work Assign-
ment is in place, sets forth the contractor's proposed techni-
cal approach for completing the tasks outlined in the Work
Assignment. It also assigns responsibilities and establishes
the project schedule and costs. Table 7 presents the sug-
gested organization of a treatability study Work Plan. The
Work Plan must be approved by the project manager before
subsequent tasks are initiated. Each of the principal Work
Plan elements is described in the following subsections.
3.5.7 Project Description
The project description section of the Work Plan provides
background information on the site and summarizes exist-
ing waste characterization data (matrix type and character-
istics and the concentrations and distribution of the con-
taminants of concern). This information can be obtained
from the Work Assignment or other background docu-
ments such as the RI. The project description also specifics
the type of study to be conducted, i.e., remedy screening,
Table 7. Suggested Organization of Treatability
Study Work Plan
1. Project Description
2. Treatment Technology Description
3. Test Objectives
4. Experimental Design and Procedures
5. Equipment and Materials
6. Sampling and Analysis
7. Data Management
8. Data Analysis and Interpretation
9. Health and Safety
10. Residuals Management
11. Community Relations
12. Reports
13. Schedule
14. Management and Staffing
15. Budget
remedy-selection testing, or RD/RA testing. For treatability
studies involving multiple tiers of testing, this section states
how the need for subsequent testing will be determined
from the results of the previous tier.
3.5.2 Treatment Technology
Description
This section of the Work Plan briefly describes the treat-
ment technology to be tested. It may include a flow dia-
gram showing the input stream, the output stream, and any
side streams generated as a result of the treatment process.
For treatability studies involving treatment trains, the tech-
nology description addresses.all the unit operations the
system comprises. A description of the pre- and posttreat-
ment requirements also may be included.
3.5.3 Test Objectives
This section of the Work Plan defines the objectives of the
treatability study and the intended use of the data (i.e., to
determine potential feasibility; to develop performance or
cost data for remedy selection; or to provide detailed de-
sign, cost, and performance data for remedy implementa-
tion). The test objectives will include performance goals
that are based on established cleanup criteria for the site or,
when such criteria do not exist, on contaminant levels that
arc protective of human health and the environment.
3.5.4 Experimental Design and
Procedures
The experimental design identifies the tier and scale of
31
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testing, .the volume of waste material to be tested, the
critical parameters, and the type and amount of replication.
Examples of critical parameters include pH, reagent dos-
age, temperature, and reaction (or residence) time. Some
form of replication is usually incorporated into a treatability
study to provide a greater level of confidence in the data.
Two methods are used to collect different types of test
sample replicates:
1) Dividing a sample in half or thirds at the end of the
experiment and analyzing each fraction. This
method provides information on laboratory error.
2) Analyzing two or three samples prepared inde-
pendently of each other under the same test con-
ditions. This method provides information on
total error.
The data quality objectives and the costs associated with
replication must be considered in the design of the experi-
ment. A matrix outlining the test conditions and the num-
ber of replicates, such as the example in Figure 5, should be
included in the Work Plan.
The specific steps to be followed in the performance of the
treatability study are described in the standard operating
procedures (SOP). The SOP should be sufficiently detailed
to permit the laboratory or field technician to conduct the
test, to operate the equipment, and to collect the samples
with minimal supervision, as shown in Example 4. The
SOP can be appended to the Work Plan.
3.5.5 Equipment and Materials
This section lists the equipment, materials, and reagents
that will be used in the performance of the treatability
study. The following specifications should be provided for
each item listed:
• Quantity
• Volume/capacity
• Calibration or scale
• Equipment manufacturer and model number
• Reagent grade and concentration
A diagram of the test apparatus also should be included in
the Work Plan.
3.5.6 Sampling and Analysis
A Sampling and Analysis Plan is required for all field
activities conducted during the RI/FS. This section de-
scribes how the existing SAP will be modified to address
field sampling, waste characterization, and sampling and
analysis activities in support of the treatability study. It
describes the kinds of samples that will be collected and
specifies the level of QA/QC required. (Preparation of the
treatability study SAP is discussed in Subsection 3.6.)
Appendix C contains waste feed characterization param-
eters specific to biological, physical/chemical, immo-
bilization, thermal, and in situ treatment technologies. Gen-
erally, these are the characterization parameters that must
be established before a treatability test is conducted on the
corresponding technology. Site-specific conditions may
necessitate the use of additional parameters.
3.5.7 Data Management
This section of the Work Plan describes the procedures for
recording observations and raw data in the field or labora-
tory, including the use of bound notebooks, data collection
sheets, and photographs. If proprietary processes are in-
volved, this section also describes how confidential informa-
tion will be handled.
3.5.8 Data Analysis and Interpretation
This section of the Work Plan describes the procedures that
will be used to analyze and interpret data from the treatability
Soil
X
Y
1
A%
3
3
- Zeolite 1
B%
3
3
C%
3
3
A%
3
3
- Zeolite
B%
3
3
C%
3
3
III - limestone
3
3
IV - control
3
3
Figure 5. Example test matrix for zeolite amendment remedy-selection treatability study.
32
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EXAMPLE 4. TREATABILITY STUDY STANDARD OPERATING PROCEDURE
Standard Operating Procedure for Thermal Desorption Remedy-Screening Treatability Study
1. Define and record planned experiment in the data book (i.e., time, temperature, soil, etc.).
2. Weigh the empty clean tray.
3. Transfer a representative aliquot of prepared soil from the jar to the tray with a stainless steel
spatula.
4. Weigh the soil and tray and adjust the soil quantity to achieve a uniform layer approximately 2.5
to 3 mm deep in the bottom of the tray.
5. Distribute and level the soil within the tray.
6. Turn on the purge-gas flow to the proper setting on the rotameter.
7. Place the tray with soil in the oven at ambient temperature and close the oven door.
8. Set the oven temperature controller set-point to the target test temperature and start the timer.
9. Monitor and record the temperatures and time periodically throughout the test period.
10. When the prescribed residence time at the target temperature is reached, shut off the oven
heater and purge-gas flow and open the oven door.
11. Cautiously withdraw the hot tray and soil with special tongs, place a cover on the tray, and
place the covered tray in a separate hood to cool for approximately 1 hour.
12. Weigh the tray (without cover) plus treated soil.
13. Transfer an aliquot (typically about 20 g) of treated soil from the tray to a tared, 60-cm3, wide-
mouth, amber bottle with Teflon-lined cap. Code, label, and submit this aliquot for analysis.
Transfer the remainder of the treated soil to an identical type bottle, label, and store as a
retainer.
14. Clean the tray, cover, and nondisposable implements by the following procedure:
• Rinse with acetone and wipe clean.
• Scrub with detergent solution and rinse with hot tap water followed by distilled water.
• Rinse with acetone and allow to dry.
• Rinse three times with methylene chloride (i.e., approximately 15 to 25 mL each rinse for
the tray).
• Air dry and store.
study, including methods of data presentation (tabular and
graphical) and statistical evaluation. (Data analysis and
interpretation are discussed in Subsection 3.11.)
3.5.9 Health and Safety
A Health and Safety Plan is required for all cleanup opera-
tions involving hazardous substances under CERCLA and
for all operations involving hazardous wastes that are con-
ducted at RCRA-regulated facilities. This section of the
Work Plan describes how the existing site or facility HSP
will be modified to address the hazards associated with
treatability testing. Hazards may include, but arc not lim-
ited to, chemical exposure; fires, explosions, or spills;
generation of toxic or asphyxiating gases; physical haz-
ards; electrical hazards; and heat stress or frostbite. (Prepa-
ration of the treatabilily study HSP is discussed in Subsec-
tion 3.7.)
3.5.10 Residuals Management
This section of the Work Plan describes the management of
treatability study residuals. Residuals generated by
treatability testing must be managed in an environmentally
sound manner. Early recognition of the types and quanti-
ties of residuals that will be generated, the impacts that
managing these residuals will have on the project schedule
and costs, and the roles and responsibilities of the various
33
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parties involved in the generation of residuals is important
for their proper disposal.
The Work Plan should include estimates of boih the types
and quantities of residuals expected to be generated during
treatability testing. These estimates should be based on
knowledge of the treatment technology and the experimen-
tal design. Project residuals may include the following:
• Unused waste not subjected to testing
• Treated waste
• Treatment residuals (e.g., ash, scrubber water, and
combustion gases)
• Laboratory samples and sample extracts
• Used containers or other expendables
• Contaminated protective clothing and debris
This section outlines how treatability study residuals will
be analyzed to determine if they are hazardous wastes and
specifies whether such wastes will be returned to the site or
shipped to a permitted treatment, storage, or disposal facil-
ity (TSDF) (see Subsection 3.9). In the latter case, this
section also identifies the waste generator (lead agency,
responsible party, or contractor) and delineates the param-
eters that will be analyzed for properly manifesting the
waste and for obtaining disposal approval from the TSDF
(see Table 8).
3.5.11 Community Relations
A Community Relations Plan is required for all removal
and remedial response actions under CERCLA. This sec-
tion describes the community relations activities that will
be performed in conjunction with the treatability study.
These activities include, but are not limited to, preparing
fact sheets and news releases, conducting workshops or
community meetings, and maintaining an up-to-date infor-
mation repository. (Conducting community relations activi-
ties for instability studies is discussed in detail in Subsec-
tion 3.8.)
3.5.12 Reports
This section of the Work Plan describes the preparation of
interim and final reports documenting the results of the
treatability study. For treauibility studies involving more
than one tier of testing, interim reports (or project brief-
ings) provide a means of determining whether to proceed to
the next tier. This section also describes the preparation of
Table 8. Typical Waste Parameters Needed to Obtain Disposal Approval at an Offsite Facility8
Incineration parameters
Total solids
% Water
%Ash
PH
Specific gravity
Flash point
Btu/pound
Total sulfide
Total sulfur
Total organic nitrogen
Total cyanide
Total phenolics
Total organic halogen (TOX)
Polychlorinated biphenyls (PCBs)
Total RCRA metals (eight)
TCLP metals
TCLP organics (D-list)
Priority pollutant organics
Volatile
Semivolatile (BN/A-extractable)
Remaining F-listed solvents
Treatment parameters
PH
Specific gravity
Oil and grease
Total organic carbon (TOC)
Total sulfide
Total cyanide
Total phenolics
Total metals (RCRA plus Cu, Ni, Zn)
TCLP metals
TCLP organics (D-list)
Landfill parameters (solids only)
% Water
%Ash
PH
Specific gravity
Total sulfide
Total cyanide
Total phenolics
PCBs
TCLP metals (extraction and RCRA)
TCLP organics (D-list)
TCLP solvents (F-list)
aAnalysis of these parameters may be required unless they can be ruled out based on knowledge of
the waste.
34
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monthly reports detailing the current and projected progress
on the project (Treatability study reporting is discussed in
detail in Subsection 3.12.)
3.5.13 Schedule
The Work Plan should contain a schedule indicating the
planned starting and ending dates for the tasks outlined in
the Work Assignment. The length of a treatability study
will vary with the technology being investigated and the
level of testing being conducted. Entire remedy-screening
studies can usually be performed within a few weeks.
Remedy-selection studies, however, may require several
months. In addition to the time required for actual testing, the
schedule must allow time for obtaining approval of the vari-
ous plans; securing any necessary environmental, testing, or
transportation permits; shipping analytical samples and re-
ceiving results; seeking review and comment on the project's
deliverables; and disposing of the project's residuals.
The schedule may be displayed as a bar chart, such as that
shown in Figure 6. In this example, both remedy-screening
and remedy-selection treatability studies are planned. Per-
formance of the selection studies is contingent upon the
results of the screening studies, which are presented in the
Interim Report. In this particular schedule, the actual
treatability tests (Subtasks 3b and 7a) will require only 1 to
2 weeks to perform. The entire two-tiered study, however,
spans a period of 8 months.
3.5.14 Management and Staffing
This section of the Work Plan identifies key management
and technical personnel and defines specific project roles
and responsibilities. The line of authority is usually pre-
sented in an organization chart such as that shown in Figure
7. The EPA Project Manager is responsible for project
planning and oversight. At Federal- and State-lead sites,
the remedial contractor directs the trcatability study and is
responsible for the execution of the project tasks. At
private-lead sites, the PRP performs this function. The
treatability study may be subcontracted wholly or in part to
a vendor or testing facility with expertise in the technology
being evaluated.
3.5.75 Budget
The treatability study budget presents the projected costs
for completing the treatability study as described in the
Work Plan. Elements of a budget include labor, adminis-
trative costs, and fees; equipment and reagents; site prepa-
ration (e.g., building a concrete pad) and utilities; permit-
ting and regulatory fees; unit mobilization; on-sccne health
and safety requirements; sample transportation and analy-
sis; emissions and effluent monitoring and treatment; unit
decontamination and demobilization; and residuals trans-
portation and disposal. Appendix B discusses these vari-
ous cost elements.
The size of the budget will generally reflect the complexity
of the treatability study. Consequently, the number of
operating parameters chosen for investigation at the rem-
edy-selection tier and the approach used to obtain these
measurements will often depend on the available funding.
For example, for some treatment processes it may be less
costly to obtain data on contaminant reduction versus reac-
tion time at the completion of a test run rather than periodi-
cally throughout the lest This kind of information can be
obtained from the technology vendor during the planning
of the treatability study.
Analytical costs can have a significant impact on the
project's overall budget. Sufficient funding must be allot-
ted for the amount of analytical work projected, the chemi-
cal and physical parameters to be analyzed, and the re-
quired turnaround time. Specialty analyses (e.g., for diox-
ins and furans) can quickly increase the analytical costs.
A 34-week remedy-screcning/rcmedy-sclcction treatability
study such as the one presented in Figure 6 can be per-
formed at a cost of between 550,000 and S100,000.
3.6 Preparing the Sampling and
Analysis Plan
3.5.7 General
A Sampling and Analysis Plan is required for all field and
test activities conducted to support a treatability study. The
purpose of the SAP is to ensure that samples obtained for
characterization and testing arc representative and that the
quality of the analytical data generated is known. The SAP
addresses field sampling, waste characterization, and sam-
pling and analysis of the treated wastes and residuals from
the testing apparatus or treatment unit.
Table 9 presents the suggested organization of the trcatability
study SAP. The SAP consists of two parts-the Field Sam-
pling Plan (FSP) and the Quality Assurance Project Plan
(QAPP).
Field Sampling Plan
The FSP component of the SAP describes the sampling
objectives; the type, location, and number of samples to be
collected; the sample numbering system; the necessary
equipment and procedures for collecting the samples; the
35
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TASK
Taskl
Work Plan Preparation
Task 2
SAP & HSP Preparation
Task3
Remedy Screening
Treaiabilily Study Execution
3a • Field Sampling/Waste Characterization
3b - Equipment Selup/Testing/Sampling
3c - Sample Analysis
Task 4
Data Analysis and Interpretation
TaskS
Interim Report Preparation & Review
Task 6
Test Plan Revision (if necessary)
Task?
Remedy Selection
Treatability Study Execution
7a - Equipment Selup/Testing/Sampling
7b - Sample Analysis
Tasks
Data Analysis and Interpretation
Task 9
Final Report Preparation and Review
Task 10
Residuals Management
Span,
Weeks
3
c
•J
4
1
3
1
4
1
2
3
2
Weeks from Project Start
i
•
2
M
•^
•
3
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^ 1
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4
2
ir
5
6
7
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8
9
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11
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12
13
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14
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r
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15
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16
17
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18
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19
20
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21
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r
22
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23
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24
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•
26
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27
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28
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M 17
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30
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r
32
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33
15
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M 18
v
34
M
16
^r
1
M 19
^r
,J
Ml Submit Work Plan Wk2
M-2 Receive Work Plan Approval Wk3
M3 Submit SAP and HSP Wk6
M4 Receive SAP and HSP Approvals Wk 8
M-5 Collect and Submit Field Samples Wk9
M-6 Receive Waste Characterization Results Wk 12
M-7 Submit Treaiabilily Samples Wk 13
M8 Receive Treatability Results Wk 16
M9 Submit Interim Report Wk 19
M 10 Project Briefing Wk 20
M 11 Submit Revised Work Plan Wk 21
M 12 Submit Treatability Samples Wk 23
M 13 Receive Treaiability Results Wk 26
M 14 Submit Draft Report Wk 30
M-15 Receive Review Comments Wk 32
M 16 Submit Final Report Wk 34
M 17 Submit Disposal Application Wk 28
M 18 Receive Disposal Approval Wk 32
M 19 Ship Residuals for Disposal Wk 34
Figure 6. Example project schedule for a two-tiered chemical dehalogenation treatabllity study.
-------
sample chain-of-cusiody procedures; and the required pack-
aging, labeling, and shipping procedures.
The sampling objectives must support the test objectives of
the treatability study. For example, if an objective of RD/
RA testing is to investigate process upsets and recovery,
the objective of field sampling should be to collect samples
representing the "worst case." If soils will be blended in
the full-scale process, however, the field sampling objec-
tives should be to collect samples representing "average"
conditions at the site.
Whatever the sampling objectives, the samples collected
must be representative of the conditions being evaluated.
Guidance on representative samples and statistical sam-
pling is contained in Test Methods for Evaluating Solid
Waste (EPA 1986).
Additional guidance for the selection of field methods,
sampling procedures, and chain-of-custody requirements
can be obtained from A Compendium of Superfund Field
Operations Methods (EPA 1987b).
Quality Assurance Project Plan
The second component of the SAP, the QAPP, details the
quality assurance objectives (precision, accuracy, repre-
sentativeness, completeness, and comparability) for criti-
cal measurements and the quality control procedures es-
tablished to achieve the desired QA objectives for a spe-
cific treatability study. Guidance for preparing the QAPP
can be obtained from Quality Assurance Procedures for
RREL (EPA 1989d) and Interim Guidelines and Specifi-
cations for Preparing Quality Assurance Project Plans
(EPA 1980). In general, QAPPs arc based on the type of
project being conducted and on the intended use of the
data generated by the project. The QAPP recommended
in Table 9 corresponds to the QA Category II plan pre-
sented in Quality Assurance Procedure for RREL. This
plan should be implemented only for remedy-selection
treatability studies requiring exceptionally high levels of
QA (i.e., where treatabilily data will play an important
role in the ROD). As discussed in the following subsec-
tions, less stringent QAPPs will be adequate for all other
treatability studies.
3.6.2 Remedy Screening
Remedy screening requires a less stringent level of QA/
QC. Technologies determined to be potentially feasible
through remedy screening arc evaluated further at the
remedy-selection tier; therefore, the QA/QC requirements
associated with this screening are less rigorous. Never-
theless, the test data should be well documented. The
EPA
Remedial Project
Manager
Quality Assurance Officer
Health & Safety Officer
EPA
Technical Experts
Contractor
Work Assignment
Manager
Work Plan
Preparation
Task Leader
SAP & HSP
Preparation
Task Leader
Subcontractor
Manager
Treatability Study
Execution
Task Leader
Data Analysis &
Interpretation
Task Leader
Final Report
Preparation
Task Leader
Figure 7. Example project organization chart.
37
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fable 9. Suggested Organization of a
Treatability Study Sampling and Analysis Plan
Field Sampling Plan
1. Site Background
2. Sampling Objectives
3. Sampling Location and Frequency
4. Sample Designation
5. Sampling Equipment and Procedures
6. Sample Handling and Analysis
Quality Assurance Project Plan
1. Project Description
2. Project Organization and Responsibilities
3. Quality Assurance Objectives
4. Site Selection and Sampling Procedures
5. Analytical Procedures and Calibration
6. Data Reduction, Validation, and Reporting
7. Internal Quality Control Checks
8. Performance and Systems Audits
9. Calculation of Data Quality Indicators
10. Corrective Action
11. Quality Control Reports to Management
12. References
Appendices
A. Data Quality Objectives
B. EPA Methods Used
C. SOP for EPA Methods Used
D. QA Project Plan Approval Form
Category IV QAPP is recommended for remedy-screening
treatability studies.
3.6.3 Remedy-Selection Testing
Remedy-selection testing requires a moderately to highly
stringent level of QA/QC. The data generated in remedy-
selection testing are generally used for evaluation and
selection of the remedy; therefore, the QA/QC associated
with this tier should be rigorous and the test data well
documented. The Category III QAPP will provide a suffi-
cient level of quality assurance for most remedy-selection
treatability studies. In cases where remedy-selection
data will be highly scrutinized or have a significant im-
pact on decision making, the Category II QAPP may be
required.
3.6.4 RD/RA Testing
Treatability testing to support remedial design/remedial
action requires a moderately to highly stringent level of
QA/QC. The data generated in RD/RA testing arc used in
support of remedy optimization and implementation; there-
fore, the QA/QC associated with this tier should be rigor-
ous and the test data well documented. In most cases, the
Category III QAPP will provide data of sufficient quality
for RD/RA treatabiliiy studies.
3.7 Preparing the Health and Safety
Plan
3.7.7 General
A project-specific Health and Safety Plan is required for all
trcatability studies conducted on site or at an offsitc labora-
tory or testing facility permitted under RCRA, including
research, development, and demonstration facilities. The
vendor or testing facility should submit the HSP with the
treatability study Work Plan. The HSP describes the work
to be performed in the field and in the laboratory, identifies
the possible physical and chemical hazards associated with
each phase of field and laboratory operations, and pre-
scribes appropriate protective measures to minimize worker
exposure. Hazards that may be encountered during
treatability studies include the following:
• Chemical exposure (inhalation, absorption, or inges-
tion of contaminated soils, sludges, or liquids)
• Fires, explosions, or spills
• Toxic or asphyxiating gases generated during storage
or treatment
• Physical hazards such as sharp objects or slippery
surfaces
• Electrical hazards such as high-voltage equipment
• Heat stress or frostbite
Table 10 presents the suggested organization of the
trcaiabiliiy study HSP, which addresses ihc Occupational
Safety and Health Administration (OSHA) requirements in
29 CFR 1910.120(b)(4). Guidance for preparing ihc HSP
is contained in two documents-A Compendium of Super-
fund Field Operations Methods (EPA 1987b) and Occupa-
tional Safely and Health Guidance Manual for Hazardous
Waste Site Activities (NIOSH/OSHA/USCG/EPA 1985).
Supervisors, equipment operators, and field technicians
engaged in onsitc operations must satisfy the training re-
quirements in 29 CFR 1910.120(c) and must participate in
a medical surveillance program, as described in 29 CFR
1910.120(0- Laboratory personnel must be trained with
38
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Table 10. Suggested Organization of a
Treatability Study Health and Safety Plan
1. Hazard Analysis
2. Employee Training
3. Personal Protective Equipment
4. Medical Surveillance
5. Personnel and Environmental Monitoring
6. Site Control Measures
7. Decontamination Procedures
8. Emergency Response Plan
9. Confined-Space Entry Procedures
10. Spill Containment Program
regard to container labeling and Material Safety Data Sheets
(MSDS) in accordance with the OSHA Hazard Communi-
cation Standard in 29 CFR 1910.1200. Before any treat-
ability studies are initiated, the Health and Safely Officer
should conduct a briefing to ensure that all personnel are
apprised of the HSP. The Health and Safety Officer also
should conduct inspections during the course of the
treatability study to determine compliance with and effec-
tiveness of the HSP.
3.7.2 Remedy Screening
The safely and health hazards associated with remedy
screening are relatively minor because of the small vol-
umes of wastes that are handled and subjected 10 testing. In
general, the HSP should provide for skin and eye proteciion
during the handling of wastes. It need not require respira-
tory proieciion if the tests are conducted in a fume hood.
3.7.3 Remedy-Selection Testing
The HSP for a remedy-selection treatabiliiy siudy must
provide for skin and eye prelection during ihe handling of
wastes. It also may require respiratory protection when
treatmeni processes lesied ai the bench scale involve mix-
ing or aeration (e.g., solidification/stabilization, ucrobic
biological treatment) that could generate dust or volatilize
organic contaminants. Because pilot-scale testing involves
significantly greater volumes of waste, the health and safety
risks will increase.
3.7.4 RD/RA Testing
Pilot- and field-scale RD/RA treatabiliiy siudics may pose
significant health and safely hazards 10 operators and onsiic
personnel. The HSP musi outline skin, eye, and respiratory
protection (Level C or higher); dccontaminaiion proce-
dures; and emergency procedures (such as equipment shut-
down and personnel evacuation).
3.8 Conducting Community Relations
Activities
3.5.7 General
Community relations activities provide interesied persons
an opporiunily to commeni on .and participate in decisions
concerning site actions, including the performance of
treatability studies. Public participaiion in ihe removal, RI/
FS, and RD/RA processes ensures that the community is
provided with accurate and timely information about site
activiiies. From the beginning of the RI/FS, a description
of the treatabiliiy siudy aciiviiies lhat will be performed
during the feasibility siudy should be included in ihe dis-
cussion on how ihe aliernaiivcs will be dclineaied for ihe
particular siie. Preseniing clear, concise explanations of
ireatability siudies (accompanied by appropriaie graphics)
before aciiviiies have been performed will create a more
open and positive Agency/public relationship.
The Agency designs and implements community relations
activiiies according 10 CERCLA and ihe Naiional Oil and
Hazardous Substances Pollution Contingency Plan. The
NCP requires the lead Agency to prepare a Communily
Relaiions Plan for all remedial response actions and for all
removal actions of more than 45 days' duration, regardless
of whether RI/FS activities are fund-financed or conducied
by PRPs (40 CFR 300.67). This plan ouilines all commu-
niiy relations aciiviiies lhai will be conducted during the
RI/FS and projecis ihe fulure aciiviiies required during
complelion of remedial design and implemenialion. These
fulure aciiviiies are outlined more clearly in a revised plan
developed aficr ihe fcasibilily siudy and before ihe reme-
dial design phase.
Guidance for preparing a CRP and conducting communiiy
relaiions aciiviiies can be acquired from Community Rela-
tions in Superfund: A Handbook (EPA 1988b). Table 11
presents ihe CRP organizaiion suggcsicd in this handbook.
Communiiy iniervicws should be conducted before the
CRP is prepared. These interviews are informal discus-
sions held with State and local officials, communiiy lead-
ers, media rcprescniaiivcs, and inicrcsied cilizens to assess
the public's concern and desire to be involved in site re-
sponse activiiies. Discussions wiih cilizens regarding the
possible need for conducting onsiic ireatabilily siudies will
allow ihe Agency lo aniicipaic and respond bcucr 10 com-
muniiy concerns as ihe ircaiabilily testing process proceeds
and will allow govcmmcni officials and cilizens 10 undcr-
39
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Table 11. Suggested Organization of
Community Relations Plan
1. Overview of Community Relations Plan
2. Capsule Site Description
3. Community Background
4. Highlights of the Community Relations
Program
5. Community Relations Activities and
Timing
Appendices
A. Contact List of Key Community Leaders
and Interested Parties
B. Suggested Locations of Meetings and
Information Repositories
stand that several technologies may be tested before the
preferred altemative(s) are listed in the final FS report.
Conducting treatability studies on site is a potentially con-
troversial issue within a community and may demand con-
siderable effort on the part of the Agency. As the site
investigation progresses, community relations activities
should focus on providing information to the community
concerning the technology screening process and on ob-
taining feedback on community concerns associated with
potentially applicable treatment technologies. Activities
may include, but are not limited to, the following:
• Preparing fact sheets and news releases describing
treatment technologies identified during the develop-
ment and screening of alternatives.
• Discussing the possibility of treatability studies being
conducted during the initial public meeting. Present-
ing professionally produced video tapes or slide shows
on treatability studies at the public meeting can demon-
strate that the Agency is attempting to educate the
public regarding the treatability study process.
• Conducting a workshop to present to concerned citizens,
local officials, and the media the Agency's rationale for
choosing the treatment technologies to be studied.
• Holding small group meetings with involved members
of the community at regular intervals throughout the
RI/FS process to discuss treatability study findings and
site decisions as they develop.
• Ensuring citizen access to treatability study information
by maintaining a complete and up-to-date information
repository.
• Presenting results of the treatability studies performed
and explaining how these results influenced the selec-
tion of the remedy at the final RI/FS public meeting.
Fact sheets on the planned treatability studies should be
made available to the public and should include a discus-
sion of treatability-specific issues such as the following:
• Uncertainties (risk) pertaining to innovative tech-
nologies
• The degree of development of potentially applicable
technologies identified for ircaiability testing
• Onsite treatability testing and analysis
• Offsite transportation of contaminated materials
• Materials handling
• Residuals management
• RI/FS schedule changes resulting from the unexpected
need for additional treauibiliiy studies
• Potential disruptions to the community
3.8.2 Remedy Screening
Remedy-screening treatability studies are relatively low-
profile and, if conducted offsite, will require relatively few
community relations activities. Distributing fact sheets and
placing the results from remedy screening in the informa-
tion repository will generally be sufficient.
3.8.3 Remedy-Selection Testing
Bench-scale remedy-selection testing may not be particu-
larly controversial if conducted offsite. Onsite bench-scale
testing, however, may require more community relations
activities.
Onsite, pilot-scale testing may attract considerable com-
munity interest. In some cases (e.g., onsite thermal treat-
ment), the strength of public opinion concerning treatability
testing may not have been indicated by the level of interest
demonstrated during the RI and previous treatability stud-
ies. Because of ihe very real potential for conflict and
misunderstanding at the remedy-selection testing stage of
the FS, it is vital that a strong program of community
relations and public participation be established well in
advance of any treatability testing.
Community acceptance is one of the nine RI/FS evaluation
40
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criteria. Remedy-selection testing may provide data that
can convince a community of a technology's ability to
remediate a site effectively. Early, open, and consistent
communication with the public and their full participation
in the decision-making process may help to prevent the
testing, development, and selection of a remedy that is
unacceptable to the community and results in delayed site
remediation and higher remediation costs.
3.3.4 RD/RA Testing
Post-ROD treatability testing may not be especially contro-
versial within a community because the remedy or rem-
edies being investigated have already been reviewed and
selected during the RI/FS. Fact sheets and news releases
covering RD/RA treatability study progress may be appro-
priate.
3.9 Complying With Regulatory
Requirements
Treatability studies involving Superfund wastes are subject
to various requirements under CERCLA [as amended in
1986 by SARA] and RCRA [as amended in 1984 by the
Hazardous and Solid Waste Amendments (HSWA)]. The
applicability of these requirements depends on whether the
studies are conducted on site (e.g., in a mobile trailer) or at
an offsite laboratory or testing facility.
Figure 8 summarizes the facility requirements for treatability
testing. Figure 9 summarizes the shipping requirements for
offsite treatability testing. These requirements are de-
scribed in the succeeding subsections.
3.9.1 Onsite Treatability Studies
Onsite treatability studies under CERCLA may be con-
ducted without any Federal, Slate, or local permits [40 CFR
300.400(e)(l)]; however, such studies must comply with
ARARs under Federal and State environmental laws to the
extent practicable or justify a waiver under CERCLA Sec-
tion 121(d)(4). For example, treatability studies involving
surface-water discharge must meet effluent limitations even
though a discharge permit is not required.
3.9.2 Offsite Treatability Studies
Section 121(d)(3) of CERCLA and Revised Procedures for
Implementing Off-Site Response Actions (the "Revised Off-
Site Policy") (EPA 1987c) generally state that offsite facili-
ties that receive CERCLA wastes must be 1) operating in
compliance with applicable Federal and State laws, and 2)
controlling any relevant releases of hazardous substances
to the environment. Currently, the Revised Off-Site Policy
docs not specifically exempt the transfer of CERCLA wastes
offsite fortrcatability studies; therefore, offsile laboratories
or testing facilities that receive CERCLA wastes must be in
compliance with the offsitc requirements.
Offsite treaiability studies under CERCLA must be con-
ducted under appropriate Federal or State permits or autho-
rization and other legal requirements. Two alternatives to a
full RCRA facility permit arc available to technology ven-
dors and other laboratory or testing facilities for compli-
ance with these requirements: a Research, Development,
and Demonstration (RD&D) permit, which covers limited-
duration and limited-quantity testing of actual hazardous
waste, and the treatability exclusion under RCRA, which
may exempt small-scale testing activities from certain RCRA
permitting requirements.*
Research, Development, and Demonstration Permits
Hazardous waste treatment facilities that propose to use an
innovative and experimental treatment technology or pro-
cess for which RCRA permit standards have not been
promulgated under Part 264 or 266 may obtain an RD&D
permit (40 CR 270.65). This provision is intended to
expedite the permit review and issuance process.
An RD&D permit may be required for laboratories or
testing facilities that perform pilot-scale tests that are likely
to exceed the storage and treatment rate limits specified
under the treatability exclusion. Limitations on the types
and quantities of hazardous waste that can be received and
treated by the facility under an RD&D permit and the
requirements for testing, reporting, and protection of hu-
man health and the environment (as deemed necessary by
the Agency) are specified in the terms and conditions of the
permit. The RD&D permits are issued for a period of 1
year and may be renewed up to three times for one addi-
tional year each.
The status of the RD&D permit authority in a particular
State can be determined by contacting the appropriate
Region's RCRA Coordinator for that State.
"The Agency intends to address large-scale treaiability
studies in separate rulcmaking at some future date; the
Agency also is considering developing regulations under
40 CFR Pan 264, Subpart Y, that would establish permit-
ting standards for experimental facilities conducting re-
search and development on the storage, treatment, or dis-
posal of hazardous waste.
41
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Will
(Testability study be
conducted on site or
off site?
Do the
Federal treatability
study sample exemption rule in
40 CFR 261.4(e) and (f) (or equivalent
State regulations) or other exclusions
in 40 CFR 261.4(b)
apply?
Will quantity
of "as received" waste
subjected to initiation of treatment
in any single day exceed
250 kg?
Will quantity
of "as received" waste
stored at the facility for purposes
of testing exceed
1000kg?
No Federal, State, or local permits
required [40 CFR 300.400(e)(l)l;
however, facility must comply with
applicable or relevant and
appropriate requirements under
Federal and State environmental
laws to the extent practicable (or
justify a waiver).
Subject to regulation under
appropriate Federal and State
environmental laws and the
Revised Off-Site Policy (OSWER
Directive 9834.11).
Conditionally exempt from RCRA treatment,
storage, and permitting requirements set forth
in 40 CFR Parts 264, 265, and 270 provided
notification, recordkeeping, and reporting
requirements are met [40 CFR 261.4(f)|.
Facility must comply with Revised Off-Site
Policy (OSWER Directive 9834.11).
Figure 8. Facility requirements for treatability testing.
42
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Do the
Federal treatability
"study sample exemption rule ir
40 CFR 26l.4(e) and (f) (or equivalent
JState regulations) or other exclusions,
in 40 CFR 261.4(b)
apply?
Yes
Will quantity of
' sample shipment exceed'
1000 kg of nonacute hazardous
waste, 1 kg of acute hazardous waste,
250 kg of soils, water, or debris^
contaminated with
vacute hazardous^
vwaste'
No
Subject to regulation under
appropriate Federal and State
environmental laws and the
Revised Off-Site Policy (OSWER
Directive 9834.11).
Conditionally exempt from RCRA generator
and transporter requirements set forth in 40
CFR Parts 262 and 263 provided
recordkeeping and reporting requirements
are met [40 CFR 26l.4(e)].
Figure 9. Shipping requirements for offsite treatability testing.
Treatability Exclusion
Effective July 19,1988, the sample exclusion provision [40
CFR 261.4(d)], which exempts waste samples collected for
the sole purpose of determining their characteristics or
composition from regulation under Subtitle C of RCRA,
was expanded to include waste samples used in small-scale
treatabilily studies (53 FR 27301). Because it is considered
less stringent than authorized State regulations for RCRA
permits, the Federal Treaiability Study Sample Exemption
Rule is applicable only in those Slates that do not have final
authorization or in authorized Stales lhat have revised their
program to adopt equivalent regulations under Slate law.
Although the provision is optional, the EPA has strongly
encouraged authorized Stales 10 adopi the exemption or to
exercise their authority to order ireaiability studies (in case
of imminent and substantial endangerment 10 health or the
environment) or to grant a general waiver, permit waiver.
or emergency permit authorily to authorize ireaiabiliiy stud-
ies. The status of ihe ireaiabiliiy exclusion in a particular
State can be determined by contacting the appropriate
Region's RCRA Coordinator for lhat Slate.
Under the treatability exclusion, persons who generaie or
collect samples of hazardous waste (as defined under RCRA)
for the purpose of conducting ireauibilily siudies are condi-
tionally exempt from the generator and transporter require-
ments (40 CFR Parts 262 and 263) when the samples are
being collected, stored, or iransported to an offsiie labora-
lory or icsting facility [40 CFR 261.4(e)] provided that:
1) The generator or sample collector uses no more
than 1000 kg of any nonacute ha/ardous waste, 1
kg of acute hazardous waste, or 250 kg of soils,
water, or debris contaminated with acute hazard-
ous waste per waste stream per treatment process.
43
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On a case-by-case basis, ihe Regional Adminis-
trator or State Director may grant requests for
waste stream limits up to an additional 500 kg of
nonacute hazardous waste, 1 kg of acute hazard-
ous waste, and 250 kg of soils, water, or debris
contaminated with acute hazardous waste.
2) The quantity of each sample shipment does not
exceed these quantity limitations.
3) The sample is packaged so that it will not leak,
spill, or vaporize from its packaging during ship-
ment, and the transportation of each sample ship-
ment complies with U.S. Department of Trans-
portation (DOT), U.S. Postal Service (USPS), or
any other applicable regulations for shipping haz-
ardous materials.
4) The sample is shipped to a laboratory or testing
facility that is exempt under 40 CFR 261.4(f) or that
has an appropriate RCRA permit or interim status.
5) The generator or sample collector maintains cop-
ies of the shipping documents, the contract with
the facility conducting the treatability study, and
records showing compliance with the shipping limits
for 3 years after completion of the treatability study.
6) The generator provides the preceding documenta-
tion in its biennial report.
Similarly, offsite laboratories or testing facilities (includ-
ing mobile treatment units) are conditionally exempt from
the treatment, storage, and permitting requirements (40
CFR Parts 264,265, and 270) when conducting treatability
studies [40 CFR 261.4(f)] provided that;
1) The facility notifies the Regional Administrator or
State Director that it intends to conduct treatability
studies.
2) The laboratory or testing facility has an EPA iden-
tification number.
3) The quantity of "as received" hazardous waste
that is subjected to initiation of treatment in all
treatability studies in any single day is less than
250kg.
4) The quantity of "as received" hazardous waste
stored at the facility does not exceed 1000 kg,
which can include 500 kg of soils, water, or debris
contaminated with acute hazardous waste or 1 kg
of acute hazardous waste.
5) No more than 90 days have elapsed since the
treatability study was completed, or no more than
1 year has elapsed since the generator or sample
collector shipped the sample to the laboratory or
testing facility.
6) The treatability study involves neither placement
of hazardous waste on the land nor open burning
of hazardous waste.
7) The facility maintains records showing compli-
ance with the treatment rate limits and the storage
lime and quantity limits for 3 years following
completion of each study.
8) The facility keeps a copy of the treatability study
contract and all shipping papers for 3 years after
the completion date of each study.
9) The facility submits to the Regional Administra-
tor or State Director an annual report estimating
the number of studies and the amount of waste to
be used in treatability studies during the current
year and providing information on treatability stud-
ies conducted during the preceding year.
10) The facility determines whether any unused sample
or residues generated by the trcatability study are
hazardous waste [unless they are returned to the
sample originator under the 40 CFR 261.4(e) ex-
emption].
11) The facility notifies the Regional Administrator or
State Director when it is no longer planning to
conduct any treatability studies at the site.
Laboratories or testing facilities that perform bench-scale
tests generally meet the storage and treatment rate limits
outlined in the preceding items. Facilities not operating
within these limitations are subject to appropriate regula-
tion.
3.9.3 Residuals Management
Treatability study residuals generated at an offsite labora-
tory or testing facility may be returned to the sample origi-
nator under the Federal Treatability Study Sample Exemp-
tion Rule (or equivalent State regulations) if the storage
time limits in 40 CFR 261.4(0 are not exceeded. This
includes any unused sample or residues. If the exemption
does not apply, the disposal of treatability study residuals is
subject to appropriate regulation, including the RCRA land
disposal restrictions for contaminated soil and debris when
these regulations become effective. Trcatability study rc-
44
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siduals managed offsite must be packaged, labeled, and
manifested in accordance with 40 CFR Part 262 and appli-
cable DOT regulations for hazardous materials under 49
CFR Part 172.
As discussed earlier, the Revised Off-Site Policy does not
specifically exempt the transfer of treatability study residu-
als offsite for disposal; therefore, offsite treatment or dis-
posal facilities that receive these wastes must be in compli-
ance with the offsite requirements. The acceptability of a
commercial facility for receiving CERCLA wastes can be
determined by contacting the appropriate Regional Offsite
Contact, as shown in Table 12.
Table 12. Regional Offsite Contacts for
Determining Acceptability Of Commercial
Facilities to Receive CERCLA Wastes8
Region
Primary
contact/phone
Backup
contact/phone
I Lin Hanifan
(617)573-5755
II Gregory Zaccardi
(212)264-9504
III Naomi Henry
(215)597-8338
IV Alan Antley
(404) 347-4450
V Gertrude Matuschkovitz
(312)353-7921
VI Trish Brechlin
(214)655-6765
VII David Doyle
(913)236-2891
VIII Felix Flechas
(303)293-1524
IX Diane Bodine
(415)744-2130
X Al Odmark
(206)553-1886
Robin Biscaia
(617)573-5754
Joe Golumbek
(212)264-2638
John Gorman
(212)264-2621
Rita Tate
(215)597-8175
Gregory Fraley
(404) 347-7603
Paul Dimock
(312)886-4445
Randy Brown
(214)655-6745
Marc Rivas
(913)236-2891
Mike Gansecki
(303)293-1510
Terry Brown
(303)293-1823
Jane Diamond
(415)744-2139
Ron Lillich
(206) 553-6646
aThese contacts are subject to change.
3.10 Executing the Study
Execution of the treatability study begins after the project
manager has approved the Work Plan and other supporting
documents. Steps include collecting a sample of the waste
stream for characterization and testing, conducting the test.
and collecting and analyzing samples of the treated waste
and residuals.
3.10.1 Field Sampling and Waste
Stream Characterization
Field samples should be collected and preserved in accor-
dance with the procedures outlined in the SAP. They
should be representative of either "average" or "worst-
case" conditions (as dictated by the test objectives), and the
sample should be large enough to complete all of the re-
quired tests and analyses in the event of some anomaly.
Collocated field samples also should be collected in accor-
dance with the QAPP. To the extent possible, field sam-
pling should be coordinated with other onsite activities to
minimize costs. Samples shipped to an offsite laboratory
for testing or analysis must be packaged, labeled, and
shipped in accordance with DOT, USPS, or other applicable
shipping regulations (see Subsection 3.9). A chain-of-
custody record must accompany each sample shipment.
The waste sample should be thoroughly mixed to ensure
that it is homogeneous. This permits a comparison of
results under different test conditions. Small-volume soil
samples can be mixed with a Hobart mixer, and large-
volume samples can be mixed with a drum roller. Stones
and debris should be removed by screening. Care must be
exercised during these procedures to avoid contaminating
the waste samples (or allowing volatiles to escape) and to
ensure effective homogenization.
Characterization samples should be collected from the same
material that will be used in the performance of the
treatability study. Characterization is necessary to deter-
mine the chemical, physical, and/or biological properties
exhibited by the waste stream so that the results of the
treatability study can be properly gauged.
3.10.2 Treatability Testing
The treatability study should be performed in accordance
with the test matrix and standard operating procedures
described in the Work Plan. Any deviations from the SOP
should be recorded in the field or laboratory notebook.
The EPA or a qualified contractor should oversee testing
conducted by vendors and PRPs. Oversight activities were
discussed in Subsection 2.5.5.
3.10.3 Sampling and Analysis
Samples of the treated waste and process residuals (e.g.,
off-gas, scrubber water, and ash for incineration tests) should
be collected in accordance with the SAP. The SAP speci-
45
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fies the location and frequency of sampling, proper con-
tainers, sample preservation techniques, and maximum hold-
ing times. Quality assurance/quality control samples will
be collected at the same time as the treatability study samples
in accordance with the QAPP. All samples must be logged
in the field or laboratory notebook. Samples shipped to an
offsite laboratory must be packaged, labeled, and shipped
in accordance with DOT, USPS, or other applicable ship-
ping regulations, and a chain-of-custody record must ac-
company each sample shipment
Treatability study samples should be analyzed in accor-
dance with the methods specified in the SAP. Normal
sample turnaround time is 3 to 5 weeks for most analyses;
the laboratory may charge a premium if results are required
in less time.
3.11 Analyzing and Interpreting the
Data
3.11.1 Data Analysis
Upon completion of a treatability study, the data must be
compiled and analyzed. The first goal of data analysis is to
determine the quality of the data collected. All data should
be checked to assess precision, accuracy, and complete-
ness. Both testing and analytical error must be assessed to
determine total error. If the QA objectives specified in the
QAPP have not been met, the project manager and the EPA
Work Assignment Manager must determine the appropri-
ate corrective action.
Data are generally summarized in tabular or graphic form.
The exact presentation of the data will depend on the
experimental design and the relationship between the vari-
ables being compared. For data presented graphically,
independent variables, which are controlled by the experi-
menter, are generally plotted on the abscissa; whereas depen-
dent variables, which change in response to changing the
independent variables, are plotted on the ordinate. Ex-
amples of independent variables are pH, temperature, re-
agent concentration, and reaction time. Examples of de-
pendent variables are removal efficiency and substrate uti-
lization.
For determining whether statistically significant differences
in treatment effectiveness exist between two or more val-
ues of an independent variable, the use of analysis of
variance and other statistical techniques may be appropri-
ate. These techniques can assist in identifying the most
cost-effective combination of parameters in a treatment
system with multiple independent variables. Statistical
analysis of treatability study data, however, should only be
performed when planned and budgeted for.
3.11.2 Data Interpretation/Pre-ROD
Interpretation of ireaiability study data must be based on
the test objectives established prior to testing. Daia inter-
pretation is an important part of the treatability study re-
port Therefore, the contractor or other party performing
the study and preparing the report must fully understand the
study objectives and the role the results will play in remedy
screening, selection, or implementation. The investigating
party, not the RPM, is responsible for interpreting the
treatability study data.
The purpose of a pre-ROD treatability investigation is to
provide the data needed for a detailed analysis of alterna-
tives and, ultimately, the selection of a remedial action that
can achieve the site cleanup criteria. The results of a
treatability study should enable the RPM to evaluate all
treatment alternatives on an equal basis during the detailed
analysis of alternatives.
The Work Plan outlines the treauibility study's test objec-
tives and describes how these objectives will be used in the
evaluation of the technology (i.e., remedy screening or
remedy selection). As discussed in Section 2, the 1990
revised NCP Section 300.430(e) specifies nine evaluation
criteria to be considered in the assessment of remedial
alternatives. These criteria were developed to address both
the specific statutory requirements of CERCLA Section
121 (threshold criteria) and the technical and policy consid-
erations that are important in the selection of remedial
alternatives (primary balancing criteria and modifying cri-
teria). The nine RI/FS evaluation criteria are as follows:
Threshold criteria:
• Overall protection of human health and the
environment
• Compliance with ARARs
Primary balancing criteria:
• Long-term effectiveness and permanence
• Reduction of toxicity, mobility, and volume through
treatment
• Short-term effectiveness
• Implcmentability
• Cost
Modifying criteria:
• State acceptance
• Community acceptance
46
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As discussed in the following subsections, treatability stud-
ies provide important data for use in the assessment of an
alternative against both the threshold criteria and the pri-
mary balancing criteria. The results of treatability studies
can also influence evaluations against the State and com-
munity acceptance criteria. Figure 10 lists factors impor-
tant to the analysis of the RI/FS evaluation criteria. These
factors are often technology-specific, as are the treatability
study data that support the analysis of each factor. Example 5
outlines some of the specific analysis factors applicable to
chemical dehalogenau'on treatment technologies and several
types of data from a chemical dehalogenation treatability
study that provide information for each of these factors.
Evaluations against the nine criteria are performed for the
overall alternative, of which the treatment technology is
only a part. The alternative will generally include additional
treatment, containment, or disposal technologies. Detailed
guidance on the Supcrfund program's remedy-selection
process as established in the 1990 revised NCP Section
300.430(f) is available in the RI/FS guidance and in A
Guide to Selecting Superfund Remedial Actions (EPA 1990b).
Threshold Criteria
The two statutory-based threshold criteria should be used
to set treatability study performance goals. Only those
alternatives that satisfy the threshold criteria are eligible for
remedy selection.
Overall Protection of Human Health and the Environment
This evaluation criterion provides an overall assessment of
how well each alternative achieves and maintains protec-
tion of human health and the environment The analysis of
overall protection will draw on the assessments conducted
under the primary evaluation criteria and the compliance
with ARARs. It will focus on the ability of an alternative to
eliminate, reduce, or control overall site risks.
Treatability studies will provide general data for the evalu-
ation under this criterion. Target contaminant concentrations
in the treated product and any treatment residuals will dem-
onstrate how well the process or treatment train can eliminate
site risks. If an ecological risk assessment is being con-
ducted, bioassessmenis of these materials will generate the
data required to evaluate the reduction in risk to site biota.
Compliance with ARARs
Applicable or relevant and appropriate requirements are
any local. State, or Federal regulations or standards that
pertain to chemical contaminant levels, locations, and ac-
tions at CERCLA sites. Treatabilily study performance
goals are generally based on ARARs. Performance data
indicating how well the process achieved these goals will
aid in evaluating the technology against the compliance
with ARARs criterion.
Chemical-specific ARARs arc health or risk-based numeri-
cal values or methodologies that, when applied to site-
specific conditions, result in the establishment of maxi-
mum acceptable amounts or concentrations of chemicals
that may be found in or discharged to the ambient environ-
ment For example, chemical-specific ARARs may in-
clude RCRA Land Disposal Restrictions (LDRs) on the
placement of treated soil or Safe Drinking Water Act Maxi-
mum Contaminant Levels (MCLs) and Clean Water Act
Water Quality Criteria for the treatment and discharge of
wastcwater. Chemical-specific ARARs will be expressed
in terms of conmminant concentrations in the treated prod-
uct and treatment residuals. Often, these ARARs define the
"target" contaminants for the treatability study.
Location-specific ARARs are restrictions placed on the
concentration of hazardous substances or the conduct of
activities solely because they are in a specific location,
such as a floodplain, a wetland, or a historic place. Loca-
tion-specific cleanup criteria may include, for example,
biotoxicity requirements for treated product and treatment
residuals if runoff from the treatment area or the disposal
site could have an impact on a sensitive wildlife habitat.
Action-specific ARARs are technology- and activity-based
requirements or limitations on actions taken with respect to
hazardous wastes. Action-specific requirements may be
particularly applicable to the discharge of residuals such as
wastewater. Target contaminant concentrations in the
treatability study wastcwater will aid in identifying action-
specific ARARs.
The actual determination of which requirements are appli-
cable or relevant and appropriate will be made by the lead
agency. Detailed guidance on determining whether re-
quirements are applicable or relevant and appropriate is
provided in CERCLA Compliance with Other Laws Manual:
Interim Final (EPA 1988c) and CERCLA Compliance with
Other Laws Manual: Part II (EPA. 1989Q.
Primary Balancing Criteria
The five primary balancing evaluation criteria should be
used for guidance in setting instability study test objectives.
Long-Term Effectiveness and Permanence
This evaluation criterion addresses risks remaining at the
site after the remedial response objectives have been met.
47
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Overall Protection of
Human Health and the
Environment
How Alternative Provides
Human Health and
Environmental Protection
Compliance With ARARs
Compliance With
Chemical-Specific ARARs
Compliance With Action-
Specific ARARs
Compliance With
Location-Specific ARARs
Compliance With Other
Criteria, Advisories, and
Guidances
Long-Term
Effectiveness and
Permanence
Reduction of Toxicity,
Mobility, or Volume
Through Treatment
Short-Term
Effectiveness
Implementability
Cost
Magnitude of
Residual Risk
Adequacy and
Reliability of
Controls
Treatment Process
Used and Materials
Treated
Amount of Hazardous
Materials Destroyed or
Treated
Degree of Expected
Reductions in Toxicity,
Mobility, and Volume
Degree to Which
Treatment Is Irreversible
Type and Quantity of
Residuals Remaining
After Treatment
Protection of
Community During
Remedial Actions
Protection of
Workers During
Remedial Actions
Environmental
Impacts
Time Until Remedial
Response
Objectives Are
Achieved
State
Acceptance*
Community
Acceptance*
Ability to Construct
and Operate the
Technology
Reliability of the
Technology
Ease of Undertaking
Additional Remedial
Actions, If
Necessary
Ability to Monitor
Effectiveness of
Remedy
Ability to Obtain
Approvals From
Other Agencies
Coordination With
Other Agencies
Availability of Offsite
Treatment, Storage,
and Disposal
Services and
Capacity
Availability of
Necessary
Equipment and
Specialists
Availability of
Prospective
Technologies
Capital Costs
Operating and
Maintenance
Costs
Present Worth
Cost
'These criteria are assessed following comment on the RI/FS report and the proposed plan.
EPA1988a
Figure 10. Evaluation criteria and analysis factors for detailed analysis of alternatives.
48
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EXAMPLE 5. APPLICABILITY OF CHEMICAL DEHALOGENATION TREATABILITY STUDY DATA
TO RI/FS EVALUATION CRITERIA
Evaluation Criteria
Analysis Factors
Treatability Study Data
Long-Term Effectiveness
and Permanence
Magnitude of residual risk
Target contaminant concentrations in
treated product and treatment
residuals
Presence of specific reaction
byproducts in treated product
Results of bioassays performed on
treated product
Reduction of Toxicity,
Mobility, or Volume
Through Treatment
Reduction in toxicity
Irreversibility of the treatment
Type and quantity of, and
risks posed by, treatment
residuals
Percent reduction in target
contaminant concentrations
Comparison of bioassay results
before and after treatment
Material balance data combined with
target contaminant concentrations in
treated product and treatment
residuals
Target contaminant concentrations in
treatment residuals
Presence of specific reaction
byproducts in treatment residuals
Results of bioassays performed on
treatment residuals
Volume of treatment residuals
Short-Term Effectiveness
Time until remedial response
objectives are achieved
Reaction time
Implementability
Reliability and potential for
schedule delays
Reliability and schedule delays during
testing
Reaction time/throughput
Physical characteristics of waste
matrix
Contaminant variability in untreated
waste
Cost
Direct capital costs
Reaction time/throughput
Reagent usage/recovery
Reaction temperature
Physical characteristics of waste
matrix
Site characteristics
Compliance with ARARs Chemical-specific ARARs
Target contaminant concentrations in
treated product and treatment
residuals
Overall Protection of
Human Health and the
Environment
Ability to eliminate, reduce,
or control site risks
Target contaminant concentrations in
treated product and treatment
residuals
Presence of specific reaction
byproducts in treated product and
treatment residuals
Results of bioassays performed on
treated product and treatment
residuals
49
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Assessment of ihe residual risks from untreated waste and
treated product left on site must involve the same assump-
tions and calculation procedures as those used in the base-
line risk assessment. If engineered controls (e.g., contain-
ment systems) are to be used to manage these remaining
materials, their adequacy and reliability also should be
evaluated under this criterion.
Remedy-selection treatability studies can often provide data
on the site's post-remediation residual risk. If treated
product will remain on site, the contaminant concentrations
in this material must meet the site's cleanup criteria. As
discussed in Subsection 2.4, these cleanup criteria translate
into specific performance goals. The concentrations of
target contaminants in the treated product and treatment
residuals after treatability testing indicate the magnitude of
the site's residual risk after treatment.
If an ecological risk assessment is to be performed, the
residual risks posed to biota by the replacement of the
treated product on site can be assessed under this criterion.
The literature survey may provide adequate data to evalu-
ate the biotoxicity of treated soils. If the literature contains
little or no biotoxicity data on the contaminants/matrix of
interest, this data need can be addressed by performing
bioassays at the remedy-selection tier. A treatability study
test objective that stipulates a reduction in the toxicity of
the treated product to test organisms will provide data for
the assessment of the technology against the long-term
effectiveness and permanence criterion.
Reduction of Toxicity, Mobility, and Volume Through Treat-
ment
This evaluation criterion addresses the statutory preference
for selecting technologies that permanently and signifi-
cantly reduce the toxicity, mobility, or volume of the haz-
ardous substances. This preference is satisfied when treat-
ment is used to reduce the principal threats at a site through
destruction of toxic contaminants, reduction of the total
mass of toxic contaminants, irreversible reducu'on in con-
taminant mobility, or reduction of the total volume of
contaminated media.
Treatability studies should provide detailed performance
data on the percentage reduction in the toxicity, mobility,
or volume of the treated product. As discussed in Subsec-
tion 2.4, a performance goal of greater than 50 percent
reduction in toxicity, mobility, or volume may be appropri-
ate at the remedy-screening tier. If this performance goal is
met, the technology is considered to be potentially feasible.
At the remedy-selection tier, the process should be capable
of achieving the site cleanup criteria with an acceptable
level of confidence. If no cleanup criteria have been estab-
lished for the site, a 90 percent reduction in contaminant
concentration will generally be an appropriate performance
goal.
Another measure of reduction in toxicity is the comparison
of bioassay results from tests performed on the waste be-
fore and after treatment. If treated product is to remain on
site, a reduction in biotoxicity should be identified as a
treatability test objective for remedy-selection testing.
Irreversibility of the treatment process is another factor in
the evaluation of a technology against this criterion. Mate-
rial balance data from a treaiability study combined with
the target contaminant concentrations found in the treated
product and treatment residuals can indicate the level of
irreversibility achieved through treatment. These data can
be used to construct a mass balance for the target contami-
nants, which will approximate the contaminant destruction
efficiency of the treatment process.
Taking the treatment residuals into consideration is an
important part of the assessment of a technology against the
reduction in toxicity, mobility, and volume criterion. Con-
centrations of target contaminants in treatability study re-
siduals indicate the risks posed by onsite treatment and
disposal of the process residuals. Data on the biotoxicity
and volume of treatabilily study residuals also provide
information for this assessment.
Short-Term Effectiveness
The short-term effectiveness criterion is concerned with
the effects of the alternative on human health and the
environment during its construction and implementation.
The RI/FS guidance outlines several factors that may be
addressed, if appropriate, when assessing an alternative
against this criterion. Treaiability studies can provide in-
formation on three of these factors: 1) protection of the
community during remedial actions, 2) protection of the
workers, and 3) time required to achieve remedial response
objectives.
If a site is located near a population center, any short-term
health risks posed by the remedial action must be ad-
dressed. The treaiability study wasie characterization can
identify some of these risks. For example, physical charac-
teristics of the wasie matrix, such as moisture content and
particle-size distribution, could indicate a potential for the
generation of contaminated dust during material-handling
operations. The presence of volatile contaminants in the
waste also could pose risks to community health during
material handling and treatment. Treatment residuals should
be carefully characterized to assist in the post-ROD design
of proper air and water treatment systems.
50
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Forthe protection of workers during implementation of the
remedy, the physical and chemical characteristics of the
untreated waste matrix and the treatment residuals are im-
portant data to be collected during treatability testing. These
data will aid in the assessment of any threats posed to
workers and the effectiveness and reliability of the protec-
tive measures to be taken. Treatability systems can also be
monitored for any adverse conditions that may develop
during testing.
The time required to achieve the remedial response objec-
tives for the site depends on the volume of soil to be treated
and the throughput of the full-scale unit or treatment train
system. Treatability studies of some technologies will
generate treatment duration data sufficient to allow esti-
mates of throughput to be made.
Implementability
This evaluation criterion assesses the technical and admin-
istrative feasibility of implementing an alternative and the
availability of the equipment and services required during
implementation. The process of designing and performing
treatability studies may assist in the analysis of the follow-
ing implementability factors:
• Difficulties associated with construction and operation
• Reliability and potential for schedule delays
• Ability to monitor treatment effectiveness
• Commercial availability of the treatment process and
equipment
The literature survey should provide historical information
regarding most of the preceding factors. If an alternative
has been shown to be capable of achieving the desired
cleanup levels but has never been demonstrated at full
scale, reliability data may be insufficient for its assessment
under the implementability criterion. In this case, data
from a pre-ROD pilot-scale lest may be required.
The reliability of the pilot system, including any schedule
delays encountered during its testing, will serve as an indi-
cator of the implementability of the full-scale system. The
treatment duration and throughput can also provide infor-
mation on potential schedule delays. Characteristics of the
matrix that could lead to equipment failure or diminished
treatment effectiveness, such as high clay content, can be
investigated during a pre-ROD treatability study. Con-
taminant variability in the untreated waste could also lead
to schedule delays by requiring repealed treatment of some
soils. Treatability testing of multiple waste types with
differing contaminant concentrations can provide impor-
tant data for analysis of the reliability factor and the imple-
mentability evaluation criterion.
Cost
The cost criterion evaluates the full-scale capital and opera-
tion and maintenance (O&M) costs of each remedial action
alternative. The assessment of this criterion requires the
development of cost estimates for the full-scale remedia-
tion of the site. These estimates should provide an accu-
racy of +50 percent to -30 percent. A comprehensive
discussion of costing procedures for CERCLA sites is in-
cluded in Remedial Action Costing Procedures Manual
(EPA 1985). The cost estimate prepared under this crite-
rion will be based on information obtained from the litera-
ture and from technology vendors. Preparation of the
estimate may also require remedy-selection treatability study
data.
Direct capital costs for treatment will include expenditures
for the equipment, labor, and materials necessary to install
the system. If the technology vendor has already con-
structed a mobile, full-scale treatment unit, treatability study
data will not be required to determine direct equipment
costs. If no full-scale system exists, however, treatability
studies can provide the operational data necessary for equip-
ment scale-up. Characteristics of the matrix identified
during treatability testing, such as panicle-size distribution
and moisture content, will have an impact on decisions
regarding front-end material handling operations and equip-
ment and post-treatment equipment for processing of the
product and residuals in a treatment train. Characteristics
of the site that may have aa impact on the logistical costs
associated with mobilization and onsite treatment can be
identified during the trcatabilily study sample-collection
visit.
Estimates of utility costs, residuals treatment and disposal
costs, and O&M costs will depend on the physical/chemi-
cal characteristics of the waste and residuals (which affect
the difficulty of treatment) and the throughput (which af-
fects the total lime for treatment). These data arc available
from remedy-selection treatability studies.
3.11.3 Data Interpretation/Post-ROD
As opposed to pre-ROD ircatabilily studies, no clearly
defined criteria exist on which to base the interpretation of
post-ROD RD/RA treatability study results. The purpose
of an RD/RA treatability study is to generate specific,
detailed design, cost, and performance data. These data are
then used 1) to prequalify vendors and processes within the
prescribed remedy, 2) to implement the most appropriate of
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the remedies prescribed in a Contingency ROD, or 3) to
support preparation of the Agency's detailed design speci-
fications and the design of treatment trains.
When an RD/RA treatability study is performed to prequalify
vendors, data interpretation consists of a straightforward
determination by the lead agency or the designer regarding
whether the vendor has attained the preset performance
goals. Little or no cost data are generated by prequalification
treatability studies. Based on these results, the lead agency
determines which vendors are qualified to bid on the RA.
Generally, the vendor should achieve results equivalent to
the cleanup criteria defined in the ROD to be considered for
prequalification.
In the case of a Contingency ROD, implementation of the
selected remedy may depend on the results of RD/RA
treatability testing. Treatability studies performed to sup-
port a Contingency ROD are designed to obtain perfor-
mance and cost data on the selected remedy that were not
available during the RI/FS. After this information is ob-
tained, data interpretation focuses on determining whether
the selected remedy will provide superior protection of
human health and the environment at a cost comparable to
that of the contingency remedy. If so, the selected remedy
is designed and implemented. If not, the contingency
remedy is implemented.
Post-ROD treatability study results are also used to sup-
port the preparation of the detailed design specifications
and the design of treatment trains. Because the treatability
study is designed to provide specific detailed operations
data on the remedy for use by the remedial design contrac-
tor, the designer is generally responsible for data interpre-
tation.
3.12 Reporting the Results
3.12.1 General
The final step in conducting a treatability study is reporting
the test results. Complete and accurate reporting is critical,
as decisions about treatment alternatives will be based
partly on the outcome of the treatability studies. Besides
assisting in the selection and implementation of the rem-
edy, the performance of treatability studies will increase
the existing body of scientific knowledge about treatment
technologies.
To facilitate the reporting of treatability study results and
the exchange of treatment technology information. Table 13
presents a suggested organization for a treatability study
report. Reporting treatability study results in this manner
will expedite the process of comparing treatment alterna-
tives. It will also allow other individuals who may be
studying similar technologies or waste matrices to gain
valuable insight into the applications and limitations of
various treatment processes.
If a treatment technology is to be tested at multiple tiers,
preparation of a formal report for each tier of the testing
may not be necessary. Interim reports prepared at the
completion of each tier may suffice. Also, it may be
appropriate to conduct a project briefing with the interested
parties to present the study findings and to determine the
need for additional testing. A final report that encompasses
the entire study should be developed after all testing is
complete.
As an aid in the selection of remedies and the planning of
future treatability studies, the Office of Emergency and
Remedial Response requires that a copy of all treatability
study reports be submitted to the Agency's RREL Treat-
ability Data Base repository, which is being developed by
the ORD (EPA 1989e). This requirement applies to both
the removal and remedial programs of Superfund. Submit-
ting treatability study reports in accordance with the sug-
gested organization will increase the usability of this re-
pository and assist in maintaining and updating the data
base. One camera-ready master copy of each treatability
study report should be sent to the following address:
Mr. Glenn M. Shaul
RREL Treatability Data Base
U.S. Environmental Protection Agency
Office of Research and Development
Risk Reduction Engineering Laboratory
26 W. Martin Luther King Drive
Cincinnati, Ohio 45268
The following subsections describe the contents of the
treatability study report.
Introduction
The introductory section of the treatability study report
contains background information about the site, waste
stream, and treatment technology. Much of this informa-
tion will come directly from the previously prepared
treatability study Work Plan. This section also includes a
summary of any treatability studies previously conducted
at the site.
Conclusions and Recommendations
This section of the report presents the conclusions and
recommendations regarding the applicability of the treat-
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Table 13. Suggested Organization of
Treatability Study Report
1. Introduction
1.1 Site description
1.1.1 Site name and location
1.1.2 History of operations
1.1.3 Prior removal and remediation
activities
1.2 Waste stream description
1.2.1 Waste matrices
1.2.2 Pollutants/chemicals
1.3 Treatment technology description
1.3.1 Treatment process and scale
1.3.2 Operating features
1.4 Previous treatability studies at the site
2. Conclusions and Recommendations
2.1 Conclusions
2.2 Recommendations
3. Treatability Study Approach
3.1 Test objectives and rationale
3.2 Experimental design and procedures
3.3 Equipment and materials
3.4 Sampling and analysis
3.4.1 Waste stream
3.4.2 Treatment process
3.5 Data management
3.6 Deviations from the Work Plan
4. Results and Discussion
4.1 Data analysis and interpretation
4.1.1 Analysis of waste stream
characteristics
4.1.2 Analysis of treatability study data
4.1.3 Comparison to test objectives
4.2 Quality assurance/quality control
4.3 Costs/schedule for performing the
treatability study
4.4 Key contacts
References
Appendices
A. Data summaries
B. Standard operating procedures
ment process tested.. It should attempt to answer questions
such as the following:
• Were the performance goals met? Were the other test
objectives achieved? If not, why not?
• Were there any problems with the treatability study
design or procedures?
• What parts of the test (if any) should have been per-
formed differently? Why?
• Are additional tiers of treatability testing required for
further evaluation of the technology? Why or why
not?
• Are data sufficient for adequately assessing the tech-
nology against the RI/FS evaluation criteria (if pre-ROD)?
• Are data sufficient for designing and implementing the
remedy (if post-ROD)?
The conclusions and recommendations should be stated
briefly and succinctly. Information that is pertinent to the
discussion and exists elsewhere in the report should be
referenced rather than restated in this section.
This section should provide an analysis of the results as
they relate to the objectives of the study and the relevant
evaluation criteria. When appropriate, the results should be
extrapolated to full-scale operation to indicate areas of
uncertainty in the analysis and the extent of this uncertainty.
Treatability Study Approach
This section reports why and how the treatability study was
conducted. It describes in detail the procedures and meth-
ods that were used to sample and analyze the waste stream
and documents any deviations from the Work Plan. Like
the introduction, this section contains information from the
previously prepared Work Plan.
Results and Discussion
The final section of the treatability study report includes the
presentation and a discussion of results (including QA/
QC). Results for the contaminants of concern should be
reported in terms of the concentration in the input and
output streams and the percentage reduction in toxicity,
mobility, or volume that was achieved. The use of charts
and graphs may aid in the presentation of these results.
This section also includes the costs and time required to
conduct the study and any key contacts for future reference.
Appendices
Summaries of the data generated and the standard operat-
ing procedures used are included in appendices.
3.12.2 Remedy Screening
Remedy screening results will be reported in the format
shown in Table 13; however, some of the sections may be
53
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abbreviated if remedy-selection testing is planned. The
conclusions and recommendations will focus primarily on
whether the technology investigated is potentially feasible
for the site and will attempt to identify critical parameters
for future treatability testing. Data will be presented in
simple tables or graphs. Statistical analysis is generally not
required. Because remedy screening does not involve rig-
orous QA/QC, the discussion of this subject will be brief.
3.12.3 Remedy-Selection Testing
Conclusions and recommendations resulting from remedy-
selection testing will focus primarily on the technology's
performance (i.e., ability to meet the performance goals
and test objectives) and will attempt to identify critical
parameters for future treatabilily testing, if needed. A
detailed discussion of data quality should be included in the
results section. The results section may also include a
statistical evaluation of the data.
3.72.4 RD/RA Testing
Conclusions and recommendations resulting from RD/RA
testing will focus on the technology's ability to achieve the
performance goals and test objectives. Any process opti-
mization parameters that were identified should also be
discussed. The results should include a detailed discussion
of data quality.
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REFERENCES
dePercin, P., E. Bates, and D. Smith. 1991. Designing
Treatability Studies for CERCLA Sites: Three Critical
Issues. J. Air Waste Manage. Assoc., 41(5):763-767.
National Institute for Occupational Safety and Health/Oc-
cupational Safety and Health Administration/U.S. Coast
Guard/U.S. Environmental Protection Agency. 1985. Oc-
cupational Safety and Health Guidance Manual for Haz-
ardous Waste Site Activities. DHHS (NIOSH) Publication
No. 85-115.
U.S. Environmental Protection Agency. 1980. Interim
Guidelines and Specifications for Preparing Quality Assur-
ance Project Plans. QAMS-005/80.
U.S. Environmental Protection Agency. 1985. Remedial
Action Costing Procedures Manual. EPA/600/8-87/049.
OSWER Directive No. 9355.0-10.
U.S. Environmental Protection Agency. 1986. Test Meth-
ods for Evaluating Solid Waste. 3rd ed. SW-846.
U.S. Environmental Protection Agency. 1987a. Data Qual-
ity Objectives for Remedial Response Activities. Develop-
ment Process (Volume I). EPA/540/G-87/003, OSWER
Directive9355.0-7B.
U.S. Environmental Protection Agency. 1987b. A Com-
pendium of Superfund Field Operations Methods. EPA/
540/P-87/001.
U.S. Environmental Protection Agency. 1987c. Revised
Procedures for Implementing Off-Site Response Actions.
OSWER Directive No. 9834.11, November 13,1987.
U.S. Environmental Protection Agency. 1988a. Guidance
for Conducting Remedial Investigations and Feasibility
Studies Under CERCLA. Interim Final. EPA/540/G-89/
004. OSWER Directive 9355.3-01.
U.S. Environmental Protection Agency. 1988b. Commu-
nity Relations in Superfund: A Handbook. Interim Ver-
sion. EPA/540/G-88/002. OSWER Directive 9230.0-3B.
U.S. Environmental Protection Agency. 1988c. CERCLA
Compliance with Other Laws Manual: Interim Final. EPA/
540/G-89/006.
U.S. Environmental Protection Agency. 1989a. Manage-
ment Review of the Superfund Program. EPA/540/8-89/
007.
U.S. Environmental Protection Agency. 1989b. Guide for
Conducting Treatability Studies Under CERCLA. Interim
Final. EPAy540/2-89/058.
U.S. Environmental Protection Agency. 1989c. Model
Statement of Work for a Remedial Investigation and Feasi-
bility Study Conducted by Potentially Responsible Parties.
OSWER Directive No. 9835.8, June 2,1989.
U.S. Environmental Protection Agency. 1989d. Quality
Assurance Procedures for RREL. RREL Document Con-
trol No. RREL(QA)-001/89.
U.S. Environmental Protection Agency. 1989c. Treatabil-
ily Studies Contractor Work Assignments. Memo from
Henry L. Longest, II, Director, Office of Emergency and
Remedial Response, to Superfund Branch Chiefs, Regions
I through X. OSWER Directive 9380.3-01, July 12, 1989.
U.S. Environmental Protection Agency. 1989f. CERCLA
Compliance with Other Laws Manual: Part II. Clean Air
Act and Other Environmental Statutes and State Require-
ments. EPA/540/G-89/009. OSWER Directive No. 9234.1-02.
U.S. Environmental Protection Agency. 1990a. Inventory
of Treatability Study Vendors, Volumes I and II. EPA/
540/2-90/003a and b.
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U.S. Environmental Protection Agency. 1990b. A Guide U.S. Environmental Protection Agency. 199Ib. Guidance
to Selecting Superfund Remedial Actions. OSWER Direc- on Oversight of Potentially Responsible Party Remedial
live 9355.0-27FS. Investigations and Feasibility Studies. Volume 1. EPA/
540/G-91/010a. OSWER Directive No. 9835.1(c).
U.S. Environmental Protection Agency. 199la. Guidance
for Increasing the Application of Innovative Treatment U.S. Environmental Protection Agency. 1991c. Administra-
Technologies for Contaminated Soil and Ground Water. live Order on Consent for Remedial Investigation/Feasibility
OSWER Directive 9380.0-17, June 10, 1991. Study. OSWER Directive No. 9835.3-2A, July 2,1991.
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APPENDIX A
SOURCES OF TREATABILITY INFORMATION
A wide range of technical resources exists within the EPA
to assist in the planning and performance of treatability
studies. These resources include reports and guidance
documents, electronic data bases, and Agency-sponsored
technical support. This appendix describes the primary
treatability study resources currently available.
Reports and Guidance Documents
Knowledge gained during the performance of treatability
studies is available in reports and technical guidance docu-
ments. The following documents can be used to identify
technology-specific treatability resources.
Superfund Treatability Clearinghouse Abstracts. U.S.
Environmental Protection Agency, Office of Emer-
gency and Remedial Response, Washington, DC. EPA/
540/2-89/00 I.March 1989.
Inventory of Treatability Study Vendors, Volumes I
and II. U.S. Environmental Protection Agency, Office
of Emergency and Remedial Response, Washington,
DC. EPA/540/2-90/003a and b, February 1990.
The Superfund Innovative Technology Evaluation Pro-
gram: Technology Profiles. U.S. Environmental Pro-
tection Agency, Office of Solid Waste and Emergency
Response and Office of Research and Development,
Washington, DC. EPA/540/5-90/006, November 1990.
Guide to Treatment Technologies for Hazardous Wastes
at Superfund Sites. U.S. Environmental Protection
Agency, Office of Solid Waste and Emergency Re-
sponse, Washington, DC. EPA/540/2-89/052, March
1989.
Treatability Potential for EPA Listed Hazardous Wastes
in Soil. U.S. Environmental Protection Agency, Of-
fice of Research and Development, Ada, OK. EPA/
600/2-89/011, March 1989.
Catalog of Supcrfund Program Publications. U.S. En-
vironmental Protection Agency, Office of Emergency
and Remedial Response, Washington, DC. EPA/540/
8-90/015, October 1990.
Electronic Information Systems
Several electronic data bases and information systems are
available to Federal, State, and private sector personnel for
retrieving innovative technology and treatability data.
RREL Treatability Data Base
Contact: Glenn Shaul
Risk Reduction Engineering Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
(513) 569-7408
Developed by the Risk Reduction Engineering Laboratory
(RREL), this data base provides data on the treatability of
contaminants in water, soil, debris, sludge, and sediment.
Target users include Federal and State agencies, academia,
and the private sector. For each contaminant, the data base
provides physical/chemical properties and treatability data
such as technology types, matrices treated, study scale, and
treatment levels achieved. Each data set is referenced and
quality-coded based on the analytical methods used, the
quality assurance/quality control efforts reported, and op-
erational information.
Version 4.0 of the data base is provided on a computer
diskette free of charge. The menu-driven program is com-
piled and does not require specialized software. Computer
hardware and software requirements are as follows:
• IBM-compatible personal computer and monitor
• 8-megabyte hard disk storage
• 640-K RAM memory
• DOS versions 2.0 to 3.3 or 5.0
• 12-pitch printer
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Requests for the data base must specify diskette format
(3'/2 HD, 5V« HD, or DD).
Alternative Treatment Technology
Information Center
Contact: Greg Ondich
Office of Environmental Engineering and
Technology Demonstration
U. S. Environmental Protection Agency
(202) 260-5747
System Operator
(301) 670-6294
System (online)
(301) 670-3808
The Alternative Treatment Technology Information Center
(ATTIC) is a comprehensive information retrieval system
containing up-to-date technical information on innovative
methods for treatment of hazardous wastes. Designed for
use by remediation personnel in the Federal, Stale, and
private sectors, ATTIC can be easily accessed free of charge
through an online system or the system operator.
The ATTIC system is a collection of hazardous waste data
bases that are accessed through a bulletin board. The
bulletin board includes features such as news items, special
interest conferences (e.g., the Bioremediation Special In-
terest Group), and a message board that allows direct com-
munications between users and with the ATTIC System
Operator (i.e.. Chat Mode). Users can access any of four
data bases: 1) the main ATTIC Data Base; 2) the RREL
Treatability Data Base; 3) the Technical Assistance Direc-
tory, which identifies experts on a given technology or
contaminant type; and 4) the Calendar of Events, which
contains information on upcoming relevant conferences,
seminars, and workshops.
The main ATTIC Data Base contains abstracts of Federal,
State, and private sector technical reports collected into a
keyword searchable format. Technologies are grouped into
five categories: 1) biological treatment, 2) chemical treat-
ment, 3) physical treatment, 4) solidification/stabilization,
and 5) thermal treatment.
In 1992, users of ATTIC will have online access to the
Inventory of Treatability Study Vendors (ITSV) data base.
The ITSV will aid in identifying vendors possessing quali-
fications to perform specific types of treatability studies
and will supplement the existing two-volume, hard-copy
publication of the same name developed by RREL. The
online version of the ITSV will give users the ability to
screen the data base electronically and to review the infor-
mation by each of three main categories: technology,
media, and contaminant group.
Users can access ATTIC directly with a personal computer
and a modem. New users can register themselves and
assign their own password by calling the ATTIC System.
Communications software should be set according to the
following parameters prior to dialing:
• Baud Rate: 1200 or 2400
• Terminal Emulation: VT-100
• Data Bits: 8
• Stop Bits: 1
• Parity: None
• Duplex: Full
The ATTIC User's Guide is available by calling the System
Operator or leaving a message on the bulletin board.
Computerized On-Line Information
System
Contact: Robert Hillger
Risk Reduction Engineering Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
(908)321-6639
System Operator
(908)906-6851
System (online)
(908) 548-4636
The Computerized On-Line Information System (COLIS)
is operated by the Technical Information Exchange (TIX)
at the EPA's Risk Reduction Engineering Laboratory in
Edison, New Jersey. A consolidation of several computer-
ized data bases, COLIS currently contains the following
files:
• Underground Storage Tank (UST) Case History File-
provides technical assistance to Federal, State, and
local officials in responding to UST releases.
• Library Search System-contains catalog cards and ab-
stracts for technical documents in the TIX Library.
• SITE Applications Analysis Reports-provides perfor-
mance and cost information on technologies evaluated
under the Supcrfund Innovative Technology Evalua-
tion (SITE) Program.
• RREL Treatability Data Base
The system is menu-oriented, and online help is available.
Federal, State, and private sector personnel can access
COLIS free of charge by using a personal computer, a
modem, and a communications program. The COLIS User's
Guide is available by contacting the System Operator.
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Vendor Information System for
Innovative Treatment Technologies
Contact:
VISITT Hotline
(800) 245-4505
The Vendor Information System for Innovative Treatment
Technologies (VISITT) is an automated data base that
provides information on innovative treatment technologies.
The data base contains information submitted by develop-
ers and vendors of innovative treatment technology equip-
ment and services. Technologies to treat ground water in
situ, soils, sludges, and sediments are included.
Each vendor file in VISITT includes information on the
vendor, the technology, and the applicable contaminants/
matrices. Performance data, unit costs, equipment avail-
ability, permits obtained, treatability study capabilities, and
references may also be available for some vendors/tech-
nologies.
The VISITT data base is available on diskette and requires
a personal computer using a DOS operating system. Future
updates may be available on-line.
Superfund Technical Support Project
Contact: Marlene Suit
Technology Innovation Office
Office of Solid Waste and Emergency
Response
U.S. Environmental Protection Agency
(703) 308-8800
The Office of Solid Waste and Emergency Response
(OSWER), Regional Superfund Offices, and the Office of
Research and Development (ORD) established the Super-
fund Technical Support Project (TSP) in 1987 to provide
direct, technology-based assistance to the Regional Super-
fund programs through ORD laboratories. The project
consists of a network of Regional Technical Support Fo-
rums, five specialized Technical Support Centers (TSCs)
located in ORD laboratories, and one TSC located at the
Office of Emergency and Remedial Response (OERR) En-
vironmental Response Branch. The objectives of the TSP
are:
• To provide state-of-the-science technical assistance to
Regional Remedial Project Managers (RPMs) and On-
Scene Coordinators (OSCs).
• To improve communications among the Regions and
the ORD laboratories.
• To ensure coordination and consistency in the applica-
tion of remedial technologies.
• To furnish high-technology demonstrations, workshops,
and information to RPMs and OSCs.
• To facilitate the evaluation and application of alterna-
tive investigatory and remedial techniques at Super-
fund sites.
The TSP is accessed by contacting one of the TSC Direc-
tors. Any Regional staff member involved in the Super-
fund program can contact the Centers directly or with the
assistance of a Forum member from their Region. Addi-
tional information on the TSP is available in:
Superfund Technical Support Project: Guide for RPMs/
OSCs. U.S. Environmental Protection Agency, Office
of Solid Waste and Emergency Response, Technology
Innovation Office, Washington, DC.
Engineering Technical Support Center
Contact: Ben Blaney or Joan Colson
Risk Reduction Engineering Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
(513)569-7406
One of the TSCs is the Engineering Technical Support
Center (ETSC) located at ORD's RREL Technical Support
Branch in Cincinnati, Ohio. The ETSC provides technical
assistance for reviewing and overseeing treatability work
plans and studies, feasibility studies, sampling plans, reme-
dial designs, remedial actions, and traditional and innova-
tive remediation technologies. Areas of expertise include
treatment of soils, sludges, and sediments; treatment of
aqueous and organic liquids: materials handling and decon-
tamination; and contaminant source control structures. The
following are examples of the types of technical assistance
that can be obtained through the ETSC and the RREL
Technical Support Branch:
• Characterization of a site for treatment technology
identification
• Performance of remedy-screening trcatabilily studies
and support for treatability studies of innovative tech-
nologies at all tiers of testing
• Review of treatability study RFPs, work plans, and
final reports
• Oversight of trcatability studies performed by contrac-
tors and PRPs
• Assistance in design and startup of full-scale systems
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Treaiabllily study assistance through the Superfund Tech-
nical Assistance Response Team (START) discussed in
Section 3.3 is also available through the ETSC contact
listed here.
Environmental Response Team
Technical Support Center
Contact: Joseph LaForNara
Environmental Response Branch
Office of Emergency and Remedial Response
U.S. Environmental Protection Agency
(908) 321-6740
The Environmental Response Team (ERT) TSC is located
at the OERR Environmental Response Branch in Edison,
New Jersey. The ERT provides technical expertise for the
development and implementation of innovative treatment
technologies through its Alternative Technology Section.
The following are examples of the types of technical assis-
tance that can be obtained through the ERT:
• Consultation on water and air quality criteria, ecologi-
cal risk assessment, and treatability study test objectives
• Development and implementation of site-specific health
and safety programs
• Performance of in-house bench- and pilot-scale
treatability studies of chemical, physical, and biologi-
cal treatment technologies
• Sampling and analysis of air, water, and soil
• Provision of onsite analytical support
• Oversight of treatability study performance
• Interpretation and evaluation of ircatability study data
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APPENDIX B
COST ELEMENTS ASSOCIATED WITH
TREATABILITY STUDIES
Section 2 of this guide describes ihree tiers of treatability
testing: remedy screening, remedy-selection testing, and
remedial design/remedial action testing. This appendix
presents the cost elements associated with the various tiers
of treatability studies. In some cases, unit costs are pro-
vided; in other cases, project-specific examples are pro-
vided that lend insight into the costs of various elements of
treatability studies.
Many cost elements are applicable to all levels of treatability
testing; however, some (e.g., the volume of residuals or
cost of analytical services) will increase from remedy screen-
ing to remedy-selection testing to RD/RA testing. Other
cost elements (e.g., site preparation and utilities) are only
applicable to RD/RA testing. Figure 11 shows the
applicability of the various cost elements to the different
treatability study tiers. The following is a discussion of
some of the key cost elements.
Vendor equipment rental is a key cost element in the per-
formance of RD/RA testing. Most vendors have estab-
lished daily, weekly, and monthly rates for the use of their
treatment systems. These charges cover wear and tear on
the system, utilities, maintenance and repair, and system
preparation. In some cases, vendors include their opera-
tors, personal protective equipment, chemicals, and decon-
tamination in the rental charge. Treatment system rental
charges typically run about 55,000 to 520,000 per week.
Also, if the vendor sets up a strict timetable for testing, the
client may be billed S4000 to S5000 a day for each day the
waste is late in arriving at the facility.
Site preparation and logistics costs include costs associated
with planning and management, site design and develop-
ment, equipment and facilities, health and safety equip-
ment, soil excavation, feed homogenization, and feed han-
dling. Costs associated with the majority of these activities
are normally incurred only with RD/RA testing of mobile
field-scale units; however, some of these cost elements
(e.g., feed homogenization and health and safety) are also
incurred in bench- and pilot-scale remedy-selection testing.
Analytical costs apply to all tiers of treatability studies and
have a significant impact on the total project costs. Several
factors affect the cost of the analytical program, including
the laboratory performing the analyses, the analytical target
list, the number of samples, the required turnaround time,
QA/QC, and reporting. Analytical costs vary significantly
from laboratory to laboratory; however, before prices are
compared, the laboratories themselves should be properly
compared. The following are typical of questions that
should be asked:
• What methods will be used for sample preparation and
analysis?
• What detection limits are needed?
• Does each laboratory fully understand the matrix that
will be received (e.g., tarry sludge, oily soil, slag) or
interference compounds that may be in the sample
(e.g., sulfide)?
If all information indicates that the laboratories are using
the same methods and equipment and understand the objec-
tives of the analytical program, the costs for analysis can be
compared.
One should also be aware that some analytes cost more to
analyze than others. Often, the project manager would like
to investigate some analytes for informational purposes
that may not be critical to the study. The decision as to
whether to analyze for these parameters could be simple if
the parameter-specific costs were known. For example,
TOC analysis of soil costs about 590/sample, whereas analy-
sis for total dioxins costs about 5650/sample.
The number of samples, turnaround time, QA/QC, and
reporting also affect analytical costs. Laboratories often
give discounts on sample quantities greater than 5, greater
than 10, and greater than 20 when the samples arrive in the
laboratory at the same time. The laboratory also applies
premium costs of 25, 50, 100, and 200 percent when ana-
61
-------
Cost Element
Labor
Testing
Equipment
Vendor Equipment
Rental
Field Instrumentation
and Monitors
Reagents
Site
Preparation
Utilities
Mobilization/
Demobilization
Permitting and
Regulatory
Health and
Safety
Sample
Transportation
Analytical
Services
Air Emission
Treatment
Effluent
Treatment
Decontamination
of Equipment
Residual
Transportation
Residual Treatment/
Disposal
Treatability Study Tier
Remedy
Screening
*
£X
^
O
o
w
o
o
o
w
^
o
o
o
w
£-N
**
Remedy
Selection
•
^
"
O
o
w
o
w
w
^
w
w
9
w
Q
^
RD/RA
•
^
™
•
•
•
•
%
•
^
•
•
•
•
•
/^-. Not applicable
( j and/or no cost
^-s incurred.
_^ May be applicable
^J and/or intermediate
^^ cost incurred.
^^ Applicable
^B and/or high cost
^^ incurred.
Figure 11. General applicability of cost elements to various treatability study tiers.
62
-------
lytical results are requested faster than the normal turn-
around time. If matrix spike and matrix spike duplicates
are required, the analytical cost will triple for those QA/QC
samples. Also, whether the laboratory provides a cover
letter with the attached data or a complete analytical report
will affect the analytical costs.
Residual transportation and disposal are also important
elements that must be budgeted in the performance of all
treatability studies. Depending on the technology(ies) in-
volved, a number of residuals will be generated. Partially
treated effluent, scrubber water, sludge, ash, spent filter
media, scale, and decontamination liquids/solids are ex-
amples of residuals that must be properly transported and
treated or disposed of in accordance with all local. State,
and Federal regulations. Unused feed and excess analytical
sample material also must be properly managed. Typi-
cally, a laboratory will add a small fee (e.g., S5 per sample)
to dispose of any unused sample material; however, the
unused raw material and residuals, which could amount to
a sizeable quantity of material, will cost significantly more
to remove. Transportation cost for a dedicated truck (as
opposed to a truck making a "milk run") is about S3.25 to
S3.75 per loaded mile. Costs for treatment of inorganic
wastewaters may range from S65 to $200 per 55-galIon
drum. Incineration of organic-contaminated wastewaters
ranges from $200 to $1000 per 55-gallon drum, and
landfilling a 55-gallon drum of inorganic solids could cost
between $75 and $200. Disposal facilities also may have
some associated fees, surcharges, and other costs for mini-
mum disposal, waste approval, State and local taxes, and
stabilization.
63
-------
APPENDIX C
TECHNOLOGY-SPECIFIC
CHARACTERIZATION PARAMETERS
The tables in Appendix C contain waste feed characterization parameters specific to biological, physical/chemical,
immobilization, thermal, and in situ treatment technologies. Generally, these are the characterization parameters that must
be established before a treatability test is conducted on the corresponding technology. Additional parameters may be
required due to site-specific conditions.
Each table is divided by technology, waste matrix, parameter, and purpose of analysis. These tables are designed to assist
the RPM in planning a treatability study.
65
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Table 14. Waste Feed Characterization Parameters for Biological Treatment
Treatment
Technology Matrix
Parameter
Purpose
General Soils/sludges Physical:
Moisture content
Temperature
Oxygen availability
Chemical:
pH
Total organic carbon
Redox potential
C:N:P ratio
Heavy metals
Chlorides/inorganic salts
Biological:
Soil biometry
Respirometry
Microbial identification
and enumeration
Microbial toxicity /growth
inhibition
Liquids Chemical:
pH
Dissolved oxygen
Chemical oxygen demand
Biological:
Biological oxygen
demand
Respirometry
Microbial identification
and enumeration
Microbial toxicity/growth
inhibition
To identify potential for microbial metabolism inhibition
and need for pretreatment.
To identify potential for microbial metabolism inhibition
and need for pretreatment.
To identify potential for microbial metabolism inhibition
and need for pretreatment.
To identify potential for microbial metabolism inhibition
and need for pretreatment.
To determine the need for possible organic carbon
supplementation to support acceptable levels of
biological activity.
To determine potential for stimulating and/or enriching
growth of indigenous aerobic, anoxic, sulfate
reducing, and obligate anaerobic microbial
populations.
To determine mineral nutrient requirements.
To identify potential for microbial metabolism inhibition
and need for pretreatment.
To identify potential for microbial metabolism inhibition
and need for pretreatment.
To determine biodegradation potentials and to
quantify biodegradation rates.
To determine oxygen uptake and biodegradation
rates.
To determine the indigenous or adapted microbial
population densities in the inoculum.
To determine microbial activity.
To identify potential for microbial metabolism inhibition
and need for pretreatment.
To determine presence or absence of oxygen as a
potential indicator, respectively, of the absence or
presence of indigenous microbial activity.
To determine total oxygen demand, both organic and
inorganic, in the liquid matrix.
To determine the fraction of the chemical oxygen
demand that is aerobically degradable.
To determine oxygen uptake and biodegradation
rates.
To determine the indigenous or adapted microbial
population densities in the inoculum.
To determine microbial activity.
66
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Table 15. Waste Feed Characterization Parameters for Physical/Chemical Treatment
Treatment
Technology
General
Matrix
Soils/sludges
Parameter
Physical:
Purpose and comments
Extraction
- Aqueous
- Solvent
- Critical fluid
- Air/steam
Chemical
dehalo-
genation
Type, size of debris
Dioxins/furans,
radionuclides, asbestos
Soils/sludges Physical:
Particle size distribution
Clay content
Moisture content
Chemical:
Organics
Metals (total)
Metals (leachable)
Contaminant
characteristics:
• Vapor pressure
• Solubility
• Henry's Law constant
• Partition coefficient
• Boiling point
• Specific gravity
Total organic carbon,
humic acid
Cation exchange capacity
Chemical oxygen demand
pH
Cyanides, sulfides,
fluorides
Biological:
Biological oxygen
demand
Soils/sludges Physical:
Moisture content
Particle-size distribution
Chemical:
Halogenated organics
Metals
Liquids
pH/base absorption
capacity
Chemical:
Halogenated organics
To determine need for pretreatmerit.
To determine special waste-handling procedures.
To determine volume reduction potential,
pretreatment needs, solid/liquid separability.
To determine adsorption characteristics of soil.
To determine conductivity of air through soil.
To determine concentration of target or interfering
constituents, pretreatment needs, extraction medium.
To determine concentration of target or interfering
constituents, pretreatment needs, extraction medium.
To determine mobility of target constituents,
posttreatment needs.
To aid in selection of extraction medium.
To determine presence of organic matter, adsorption
characteristics of soil.
To determine adsorption characteristics of soil.
To determine fouling potential.
To determine pretreatment needs, extraction medium.
To determine potential for generating toxic fumes at
low pH.
To determine fouling potential.
To determine reagent formulation/loading.
To determine experimental apparatus.
To determine concentration of target constituents,
reagent requirements.
To determine concentration of other alkaline-reactive
constituents, reagent requirements.
To determine reagent formulation/loading.
To determine concentration of target constituents,
reagent requirements.
67
-------
Table 15. (continued)
Treatment
Technology
Matrix
Parameter
Purpose and comments
Oxidation/ Soils/sludges Physical:
reduction Total suspended solids
Chemical:
Chemical oxygen demand
Metals (Cr+3,Hg. Pb, As)
Flocculation/ Liquids
sedimentation
Carbon
adsorption
Ion
exchange
Liquids
Gases
Liquids
pH
Physical:
Total suspended solids
Specific gravity of
suspended solids
Viscosity of liquid
Chemical:
pH
Oil and grease
Physical:
Total suspended solids
Chemical:
Organics
Oil and grease
Biological:
Microbial plate count
Physical:
Particulates
Chemical:
Volatile organic
compounds, sulfur
compounds, mercury
Physical:
Total dissolved solids
Total suspended solids
Chemical:
Inorganic cations and
anions, phenols
Oil and grease
To determine the need for slurrying to aid mixing.
To determine the presence of oxidizable organic
matter, reagent requirements.
To determine the presence of constituents that could
be oxidized to more toxic or mobile forms.
To determine potential chemical interferences.
To determine reagent requirements.
To determine settling velocity of suspended solids.
To determine settling velocity of suspended solids.
To aid in selection of flocculating agent.
To determine need for emulsifying agents, oil/water
separation.
To determine need for pretreatment to prevent
clogging.
To determine concentration of target constituents,
carbon loading rate.
To determine need for pretreatment to prevent
clogging.
To determine potential for biodegradation of adsorbed
organics and/or problems due to clogging or odor
generation.
To determine need for pretreatment to prevent
clogging.
To determine concentration of target constituents,
carbon loading rate.
To determine concentration of target constituents,
carbon loading rate.
To determine need for pretreatment to prevent
clogging.
To determine concentration of target constituents.
To determine need for pretreatment to prevent
clogging.
68
-------
Table 15. (continued)
Treatment
Technology
Matrix
Parameter
Purpose and comments
Liquid/liquid Liquids
extraction
Reverse Liquids Physical:
osmosis Total suspended solids
Chemical:
Metal ions, organics
PH
Residual chlorine
Biological:
Microbial plate count
Physical:
Solubility, specific gravity
Chemical:
Contaminant
characteristics:
• Solubility
• Partition coefficient
• Boiling point
Oil/water Liquids Physical:
separation Viscosity
Specific gravity
Settleable solids
Temperature
Chemical:
Oil and grease
Organics
Air/steam Liquids Chemical:
stripping Hardness
Volatile organic
compounds
Contaminant
characteristics:
• Solubility
• Vapor pressure
• Henry's Law constant
• Boiling point
* Mass transfer coefficient
Chemical oxygen demand
Biological:
Biological oxygen
demand
Filtration Liquids Physical:
Total suspended solids
Total dissolved solids
To determine need for pretreatment to prevent
plugging of membrane.
To determine concentration of target constituents.
To evaluate chemical resistance of membrane.
To evaluate chemical resistance of membrane.
To determine potential for biological growth outside
membrane that would cause plugging.
To determine miscibility of solvent and liquid waste.
To aid in selection of solvent, separation of phases,
etc.
To determine separability of phases.
To determine separability of phases/emulsions.
To determine amount of residual solids.
To determine rise rate of oil globules.
To determine concentration of target constituents.
To determine need for posttreatment.
To determine potential for scale formation.
To determine concentration of target constituents.
To determine strippability of contaminants, size of
units, and need for posttreatment.
To determine stripping factor.
To determine packing height.
To determine fouling potential.
To determine fouling potential.
To determine need for pretreatment to prevent
clogging.
To determine need for posttreatment.
69
-------
Table 15. (continued)
Treatment
Technology
Matrix
Parameter
Purpose and comments
Dissolved air
flotation
Liquids
Neutralization Liquids
Precipitation Liquids
Oxidation Liquids
(alkaline
chlorination)
Reduction Liquids
Hydrolysis Liquids
Physical:
Total suspended solids
Specific gravity
Chemical:
Oil and grease
Volatile organic
compounds
Chemical:
PH
Metals
Acidity/alkalinity
Cyanides, sulfides,
fluorides
Chemical:
Metals
pH
Organics, cyanides
Chemical:
Cyanides
pH
Organics
Redox potential
Chemical:
Metals (Cr+6, Hg, Pb)
Chemical:
Organics
pH
To determine amount of residual sludge.
To determine separability of phases.
To determine concentration of target constituents.
To determine need for air emission controls,
posttreatment.
To determine reagent requirements.
To determine need for posttreatment.
To determine reagent requirements.
To determine potential for generating toxic fumes at
low pH.
To determine concentration of target constituents,
reagent requirements.
To determine solubility of metal precipitates, reagent
requirements.
To determine concentration of interfering constituents,
reagent requirements.
To determine concentration of target constituents,
reagent requirements.
To determine suitable reaction conditions.
To determine potential for forming hazardous
compounds with excess chlorine (oxidizing agent).
To determine reaction success.
To determine concentration of target constituents,
reagent requirements.
To determine concentration of target constituents,
reagent requirements, posttreatment needs.
To determine reagent requirements.
70
-------
Table 16. Waste Feed Characterization Parameters for Immobilization
Treatment
Technology
Matrix
Parameter
Purpose and comments
Stabilization/ Soils/sludqes Physical:
solidification
Vitrification Soils/sludges
Description of materials
Particle-size analysis
Moisture content
Density testing
Weight ratio additives to
waste
Chemical:
Total organic content
PH
Alkalinity
Interfering compounds
Indicator compounds
Leach testing
•TCLP
• TCLP-water
Heat of hydration
Total waste analysis
Physical:
Depth of contamination
and water table
Soil permeability
Metal content of waste
material and placement of
metals within the waste
Combustible liquid/solid
content of waste
Rubble content of waste
Void volumes
Moisture content
Particle-size analysis
Chemical:
Leach testing
Total waste analysis
To determine waste handling methods (e.g., crusher,
shredder, removal equipment).
To determine surface area available for binder contact
and leaching.
To determine amount of water to add/remove in S/S
mixing process.
To evaluate changes in density between untreated and
treated waste and to determine volume increase.
To determine effects of dilution due to volume increase.
To determine reagent requirements.
To evaluate changes .in leaching as function of pH
between untreated and treated waste.
To evaluate changes in leaching as function of alkalinity
between untreated and treated waste.
To evaluate viability of S/S process. (Interfering
compounds are those that impede fixation reactions,
cause adverse chemical reactions, generate excessive
heat; interfering compounds vary with type of S/S).
To evaluate performance.
To evaluate performance based on regulatory test.
To evaluate performance under natural conditions.
To measure temperature changes during mixing.
To evaluate performance.
Technology is applied in unsaturated soils.
Dewatering of saturated soils may be possible.
Technology is applied in unsaturated soils.
Greater than 5 to 15% by weight or significant amounts
of metal near electrodes interfere with process.
Greater than 5 to 15% by weight interferes with process
(may ignite).
Greater than 10 to 20% by weight interferes with
process.
Large, individual voids (greater than 150 ft^) impede
process, may cause subsidence.
To determine power requirements.
To determine surface area available for binder contact
and leaching.
To evaluate performance.
To evaluate performance.
71
-------
Table 17. Waste Feed Characterization Parameters for Thermal Treatment
Treatment
Technology Matrix
General Soils/sludges
Parameter
Physical:
Purpose and comments
Liquids
Moisture content
Ash content
Ash fusion temperature
Heat value
Chemical:
Volatile organics,
semivolatile organics
Principal organic
hazardous constituents
Total halogens
Total sulfur, total nitrogen
Phosphorus
PCBs and dioxins (if
suspected)
Metals
Physical:
Viscosity
Total solids content
Particle-size distribution of
solid phases
Heat value
Chemical:
Volatile organics,
semivolatile organics
Principal organic
hazardous constituents
Total halogens
Total sulfur, total nitrogen
Phosphorus
PCBs, dioxins (if
suspected)
Affects heat value and material handling.
To determine the amount of ash that must be disposed
or treated further.
High temperature can cause slagging problems with
inorganic salts having low melting points.
To determine auxiliary fuel requirements and feed rates.
Allows determination of principal organic hazardous
constituents.
Allows determination of destruction and removal
efficiency.
To determine air pollution control devices for control of
acid gases.
Emissions of SOx and NOx are regulated; to determine
air pollution devices.
Organic phosphorus compounds may contribute to
refractory attack and slagging problems.
99.9999% destruction and removal efficiency required
for PCBs; safety considerations; incineration is required
if greater than 500 ppm PCBs present.
Volatile metals (Hg, Pb, Cd, Zn, As, Sn) may require
flue-gas treatment; other metals may concentrate in ash.
Trivalent chromium may be oxidized to hexavalent
chromium, which is more toxic. Presence of inorganic
alkali salts, especially potassium and sodium sutfate,
can cause slagging. Determine posttreatment needs.
Waste must be pumpable and atomizable.
Affects pumpability and heat transfer.
Affects pumpability and heat transfer.
Determine auxiliary fuel requirements and feed rates.
Allows determination of principal organic hazardous
constituents.
Allows determination of destruction and removal
efficiency.
To determine air pollution control devices for control of
acid gases. Chlorine could contribute to formation of
dioxins.
Emissions of SOx and N^x are regulated; to determine
air pollution devices.
Organic phosphorus compounds may contribute to
refractory attack and slagging problems.
99.9999% destruction and removal efficiency required
for PCBs; safety considerations; incineration is required
if greater than 500 ppm PCBs present.
72
-------
Table 17. (continued)
Treatment
Technology
Matrix
Parameter
Purpose and comments
General
(cont.)
Liquids
Metals
Rotary kiln
Soils/sludges Physical:
Particle-size distribution
Debris Physical:
Amount, description of
materials
Presence of spherical or
cylindrical wastes
Fluidized-bed Soils/sludges Physical:
Ash fusion temperature
Ash content
Bulk density
Thermal Soils/sludges Physical:
desorption Moisture content
Particle-size distribution
Chemical:
PH
Volatile organic
contaminants
Volatile metals
Nonvolatile metals
Total chlorine
Total organic content
Liquids Physical:
Total solids content
Volatile metals (Hg, Pb, Cd, Zn, As, Sn) may require
flue-gas treatment; other metals may concentrate in
ash. Trivalent chromium may be oxidized to
hexavalent chromium, which is more toxic. Presence
of inorganic alkali salts, especially potassium and
sodium sulfate, can cause slagging. Determine
posttreatment needs.
Fine particle size results in high paniculate loading
and slagging. Large particle size may present feeding
problems.
Oversized debris presents handling problems and kiln
refractory loss.
Spherical or cylindrical waste can roll through kiln
before combusting.
For materials with a melting point less than 1600°F,
particles melt and become sticky at high
temperatures, which causes defluidization of the bed.
Ash contents greater than 65% can foul the bed.
As density increases, particle size must be decreased
for sufficient heat transfer.
Affects heating and materials handling.
Large particles result in poor performance. Fine silt or
clay generate fugitive dusts.
Very high or very low pH waste may corrode
equipment.
To determine concentration of target constituents,
posttreatment needs.
To determine concentration of target constituents,
posttreatment needs.
To determine posttreatment needs.
Presence of chlorine can affect volatilization of some
metals.
Limited to -10 percent or less.
Minimum of 23-30 percent solids required.
73
-------
Table 18. Waste Feed Characterization Parameters for In Situ Treatment
Treatment
Technology
Matrix
Parameter
Purpose and comments
Vapor extraction
-Vacuum extraction
-Steam-enhanced
-Hot-air-enhanced
Solidification/
stabilization
(undisturbed)
-Pozzolanic
-Polymerization
-Precipitation
Soil flushing
-Steam/hot water
•Surfactant
•Solvent
Soils/sludges
Vitrification
Electrokinetics
Microbial
degradation
-Aerobic
-Anaerobic
Adsorption (trench)
Physical:
Vapor pressure of contaminants To estimate ease of volatilization.
Soil permeability, porosity,
particle-size distribution
Depth of contamination and
water table
To determine if the soil matrix will allow adequate
air and fluid movement.
To determine relative distance; technology
applicable in vadose zone.
Soils/sludges Physical:
Presence of subsurface barriers To assess the feasibility of adequately delivering
Soils/sludges
Soils/sludges
Soils/sludges
Soils/sludges
Soils/sludges
Soils/sludges
(e.g., drums, large objects,
debris, geologic formations)
Depth to first confining layer
Physical:
Presence of subsurface barriers
(e.g., drums, large objects,
debris, geologic formations)
Hydraulic conductivity
Moisture content (for vadose
zone)
Soil/water partition coefficient
Octanol/water partition coefficient
Cation exchange capacity
Alkalinity of soil
Chemical:
Major cations/anions present in
soil
Physical:
Depth of contamination and
water table
Physical:
Hydraulic conductivity
Depth to water table
Chemical:
Presence of soluble metal
contaminants
Physical:
Permeability of soil
Chemical/biological:
Contaminant concentration and
toxicity
Chemical/biological:
Contaminant concentration and
toxicity
Physical:
Depth of contamination and
water table
Horizontal hydraulic flow rate
and mixing the S/S agents.
To determine required depth of treatment.
To assess the feasibility of adequately delivering
the flushing solution.
To assess permeability of the soils.
To calculate pore volume to determine rate of
treatment.
To assess removal efficiency and to correlate
between field and theoretical calculations.
To assess removal efficiency and to correlate
between field and theoretical calculations.
To evaluate potential for contaminant flushing.
To estimate the likelihood of precipitation.
To estimate the likelihood of precipitation; to
estimate potential for plugging of pore volumes.
Technology is only applied in the unsaturated
zone.
Technology applicable in zones of low hydraulic
conductivity.
Technology applicable in saturated soils.
Technology applicable to soluble metals, but not
organics and insoluble.
To determine ability to deliver nutrients or oxygen
to matrix and to allow movement of microbes.
To determine viability of microbial population in
the contaminated zone.
To determine viability of microbial population in
the contaminated zone.
Technology applicable in saturated zone.
To determine if ground water will come into
contact with adsorbent.
74
-------
United States
Environmental Protection Agency
Center lor Environmental Research Information
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-------
Section 6
-------
GROUNDWATER TREATMENT
STUDENT PERFORMANCE OBJECTIVES
At the conclusion of this unit, students will be able to:
1. Define hydrogeology, aquifer, and aquitard
2. List the advantages and disadvantages of permeable treatment
beds using:
a. Crushed limestone
b. Activated carbon
c. Glauconitic green sand
3. Describe a typical recovery well
4. Describe a typical interceptor trench
5. List the function of the following ground water treatment and
discharge system components
a. Oil/water separators
b. Filters
c. Clarifiers
d. Oxidation basins
NOTE: Unless otherwise stated, the conditions for
performance are using all references and materials
provided in the course, and the standards of
performance are without error.
7/95
-------
NOTES
GROUNDWATER
TREATMENT
S-1
GROUNDWATER TREATMENT
• Hydrogeology
• Treatment beds
• Pump and treat systems
Ground surface
Unsaturated
(vadose)
zone
Saturated
zone
(aquifer)
S-2
apillary rise
from water table
S-3
7/95
Groundwater Treatment
-------
AQUIFERS AND AQUITARDS
Unconfmed aquifer
Aquitard
Confined aquifer
Aquitard
Confined aquifer
S-4
PLUME STRATIFICATION
Unconfined aquifer — Groundwater flow
NOTES I ^
Groundwater Treatment
7/95
-------
NOTES
GROUNDWATER QUALITY
• pH
• Temperature
• Total hardness
• Iron •. --- (V /)(toj y
• Dissolved oxygen
• Total solids
Permeable Treatment Bed
Monitoring
well
Production
well
Aqultard
S-7
MEDIA USED IN
PERMEABLE TREATMENT BEDS
• Crushed limestone
• Activated carbon
• Glauconitic green sands
S-8
u
'/?
I/UUL*M
7/95
Groundwater Treatment
-------
NOTES
CRUSHED LIMESTONE
TREATMENT BED (Advantages)
• Neutralizes acidic groundwater
• Removes some heavy metals
• Materials readily available
• Inexpensive
S-9
CRUSHED LIMESTONE
TREATMENT BED (Disadvantages)
Cementation of the bed may occur
Channeling of the bed may occur
Will not remove organic contaminants
Maintenance necessary
S-10
ACTIVATED CARBONJTREATMENT
BEDS (Advantages)
Removes nonpolar organics
Readily available
Easy to install
S-11
Groundwater Treatment
7/95
-------
NOTES
ACTIVATED CARBON TREATMENT
BEDS (Disadvantages)
• Will not remove polar organics
• Desorption may occur
• Removing carbon is hazardous
• Material is expensive
• Plugging may occur
S-12
rGLAUCONITIC GREEN SAND
TREATMENT BEDS (Advantages)
• Removes many heavy metals
• Short residence time
• Little material required for bed
• Material abundant in eastern United States
• Excellent permeability
S-13
GLAUCONITIC GREEN SAND
TREATMENT BEDS (Disadvantages)
• Saturation characteristics unknown ^
• Limited by availability of material
• May reduce pH significantly
• Plugging of bed may occur
• Removal efficiencies unknown
S-14
7/95
Groundwater Treatment
-------
PUMP AND TREAT
Advantages
Treats most contaminants
High design flexibility
High reliability
S-15
PUMP AND TREAT
Disadvantages
Could be very expensive
Requires treatment of large quantities of
uncontaminated water
Energy and labor intensive
Regulatory problems with discharge
Fine-grained material a problem
i
S-16
NOTES
Groundwater Treatment 6 7/95
-------
Land surface-^
>^ i Potentiometric surface ^ i NV
'rft*
-------
LNAPL Recovery
LNAPL skimming system
Water pumping system
LNAPL
Groundwater
S-19
Carbon
contactors Sand filter
Treated water
flow
Groundwater
flow
S-20
NOTES
Groundwater Treatment
7/95
-------
Clarifier
Oil/water separator
Chemical
addition/
pH control
Flocculant
addition
(alum)
S-21
NOTES
7/95
Groundwater Treatment
-------
NOTES
Oil/water
separator
Sand
filter
S-22
S-23
Groundwater Treatment
10
7/95
-------
REFERENCES
U.S. EPA. 1995. Introduction to Groundwater Investigations: Courseware. U.S. Environmental
Protection Agency, Environmental Response Training Program, Cincinnati, OH.
Nalco Chemical Company. 1988. The Nalco Water Handbook. Second Edition. Frank N.
Kemmer, Ed. McGraw-Hill, Inc., New York.
7/95 11 Groundwater Treatment
-------
Section 7
-------
VOLATILIZATION
STUDENT PERFORMANCE OBJECTIVES
At the conclusion of this unit, students will be able to:
1. Describe the air stripping process
2. List four factors that influence the operation of a packed
tower air stripping unit
3. Describe the operation of a soil vapor extraction system
4. Describe five design and operational conditions pertinent to
a soil vapor extraction system
5. Describe the air sparging process
6. Describe treatment selection considerations for air sparging.
NOTE: Unless otherwise stated, the conditions for
performance are using all references and materials
provided in the course, and the standards of
performance are without error.
7/95
-------
NOTES
VOLATILIZATION
S-1
VOLATILIZATION TREATMENTS
• Air stripping
• Soil vapor extraction (SVE)
• Air sparging
S-2
AIR STRIPPING INTRODUCTION
• Physical separation of contaminants
• Most common treatment for groundwater
• Part of treatment tram
S-3
7/95
Volatilization
-------
NOTES
AIR STRIPPING INTRODUCTION (cont.)
Applicable to volatile and semivolatile organic
compounds (VOCs and SVOCs)
Stripped contaminants concentrated or
destroyed
S-4
EFFICIENCY AND
EFFECTIVENESS
98% removal of most VOCs from water
80% removal of most SVOCs
Not effective for low-volatility compounds,
metals, or inorganics
Enhances carbon systems
S-5
LIMITATIONS
>• Henry's Law Constant >0.003 atm/mol/m3
• Scaling from iron or carbonates
• Biological fouling
• pH
s-e
Volatilization
7/95
-------
DESIGN CONSIDERATIONS
Contaminant characteristics
Contaminant concentrations
Effluent discharge requirements
Influent temperature
DESIGN VARIABLES
Air-to-water ratio
Type of packing and placement
Packing (column) height
Tower diameter
NOTES
S-7
S-8
tutivdo
7/95 3 Volatilization
-------
Storage
tank
\ /
Off-gas
treatment
Effluent
treatment
Packed Column Air Stripping System
S-9
Influent
/\
Contaminated
Groundwater
Water
Level
\
S*
\
Mist Eliminator
Redistribution
Rings(j^x/w
Stainless Steel Screen
Air Inlet
Discharge
Air
Packed Column Air Stripper
8,10
/VOTES
tvui
Hv
Volatilization
7/95
-------
NOTES
PROCESS RESIDUALS
Off-gas requires treatment
- Carbon
- Catalytic oxidation
- Incineration
Effluent may require treatment
- Chemical or carbon
- Biological
S-11
STEAM STRIPPING
Same basic configuration
Influent preheated
Steam injected into column
Henry's Law Constant >0.0004 atm/mol/m3^
S-12
**<-
SOIL VAPOR EXTRACTION
Introduction
• /n-s/fu treatment
• Removes VOCs and SVOCs
• Applicable to vadose or unsaturated zone
• Uses vapor extraction wells (vacuum) (W\.
• Addition of air injection wells
• Collects and treats soil volatiles
S-13
is
/)
7/95
Volatilization
-------
NOTES
APPLICABILITY
Very site specific
Soil characteristics
- Coarse, well-drained
- Low organic carbon content
Finer, wetter soils (lower removal rates)
S-14
SVE vs. EXCAVATION AND
TREATMENT
SVE favorable if:
• Volume >500 yd3
• Contamination >20-30 ft deep4~/)iick
• Area >200 ft2 at constant depth
S-15
SVE vs. EXCAVATION AND
TREATMENT (cont.)
SVE favorable if:
• Depth to groundwater controllable (:
• Soils are homogeneous
s-i8
Volatilization
7/95
-------
SOIL VAPOR EXTRACTION
Limitations
Soils with low air permeability
Soils with high organic carbon content
Low soil temperature
Vapor pressure of contaminant <1 mm HgL"
Water-soluble organic compounds
S-17
Volatilization System
Extraction air
bypass valve
Extraction air
flow meter
Induced draft
extraction fan
Extraction
manifold
Extraction air
sampling port
Vapor
treatment
Impermeable
Soil contamination
Slotted:
vertical
extraction
vent pipe
NOTES
7/95
Volatilization
-------
NOTES
SVE DESIGN AND OPERATION
CONSIDERATIONS
Extraction well placement critical
Maximize vapor flow in contaminated zone
Minimize vapor flow into outlying area
Active air injection wells
Passive air injection wells
S-19
SVE DESIGN AND OPERATION
CONSIDERATIONS (cont.)
Screened PVC pipe most common
Screened pipe in permeable packing
Unscreened pipe encased in grout
Horizontal system if vadose zone < 10 ft
Cap may be required
S-20
SOIL VAPOR EXTRACTION
Costs
• Average $50/ton
• Range $10 to $150/ton
• Contaminant characteristic and
concentration dependent
• Reduce contaminant concentration
- Decrease efficiency
- Increase cost
S-21
Volatilization
7/95
-------
IN-SITU STEAM EXTRACTION
• Inject steam to raise contaminant vapor
pressure
• Use cutter bits and mixing blades
• Bench scale and pilot studies
• Excessive process costs
S-22
AIR SPARGING PROCESS
Two-step process
VOCs transferred from subsurface
saturated zone to vadose zone
• Clean air sparged into contaminated
aquifer
• VOCs removed from vadose zone by SVE
S-23
REMEDIATION MECHANISM
• Contaminant mass transport
• Enhancement of biological activity
• One process usually dominant
S-24
NOTES
A
7/95
Volatilization
-------
NOTES
MASS TRANSFER
Due to turbulence and mixing of
groundwater
Increases release rate of contaminant from
soil into groundwater
Enhances volatilization of light nonaqueous
phase liquids (LNAPLs)
S-2S
BIODEGRADATION MECHANISM
• Increases oxygen content 4
• Uses indigenous microorganisms
• Can add nutrients
• Decreases VOCs in extracted air
• Not effective for chlorinated organics
5-26
TREATMENT SELECTION
CONSIDERATIONS
• Soil depth to groundwater
• Soil permeability
• Horizontal vs. vertical flow
• Air pocket formation
S-27
Volatilization
10
7/P5
-------
TREATMENT SELECTION
CONSIDERATIONS (cont.)
• Henry's Law Constant and solubility of
contaminants
• LNAPLs
• Metals, inorganics, and bacteria
• Migration of dense nonaqueous phase
liquids (DNAPLs)
S-28
OVERLY PRESSURIZED AIR
SPARGING SYSTEM
U.S. EPA
S-28
INJECTION PRESSURE DESIGN
• Measure or calculate hydrostatic head
- Coarse soils: add 1 -2 psi
- Finer grained soils: 2 times head
pressure
• Evaluate fracturing and air channeling
• Located sparger >5 ft below aquifer
surface
S-30
NOTES
7/95
11
Volatilization
-------
AIR SPARGING PROCESS SCHEMATIC
Atmospheric air
Recycled air for closed loop operation
\/
Contaminant-
free ajr
Atmosphere air for
vacuum regulation
Blower or
compressor
Sparge well
Extracted
air
Air/water
separator
Vacuum
blower
Vent to
atmosphere
Air
emissions
treatment
Soil vapor
extraction well
U.S. EPA 1992b
S-31
NOTES
Volatilization
12
7/95
-------
NOTES
SPACE CONFIGURATION
US. EPA 1892b
S-32
NESTED WELLS
U.S. EPA 190Zb
S-33
HORIZONTAL WELLS
Extraction
well
1
L L L L L
Sparging
well
US. EPA 1992b
S-34
7/95
13
Volatilization
-------
NOTES
COMBINED HORIZONTAL/VERTICAL
U.S. EPA
Extraction
well
umimimmm
III
^,
\_
=
=
Sparging
well
1 Illlllllllllll 1 II 1
III -
_^// '
^S
»B92b
S-35
AIR FLOW OPERATING
CONSIDERATIONS
Pulsing may give better results<
Minimize continuous flow through
saturated zone
Typical flows 2-10 cfm
Radius of influence (ROI)
- 5-30 ft in coarse soils
- > 60 ft in stratified soils
S-38
ACTUAL RESULTS
Pump and treat systems "retrofitted"
Treatment time reduced from years to
months
S-37
Volatilization
14
7/95
-------
NOTES
CASE STUDIES
Sparging Trench Design, Virginia
• Bulk fuel storage leak
• 400 ft trench perpendicular
to groundwater flow
• Modelled as continuously
stirred tank reactor
• Multiorifice slot system
for air distribution
CASE STUDIES (cont.)
Pilot Test, New Jersey
S-38
VOC spill site
Air injection at 4-5 scfm
Injection pressure 10-13 psi
SVE levels increased from 2,000
to 7,000 ppm
One zone increased from 9,000
to 45,000 ppm
S-38
CASE STUDIES (cont.)
Gasoline Spill Site, Rhode Island
• 30,000 ppb BTEX in groundwater
• SVE showed <5 ppb BTEX
• Goal: reduce BTEX in
groundwater to < 10,000 ppb
• Air injected at 2-6 scfm and
6-8 psi
• Goal met in 2 months
S-40
7/95
15
Volatilization
-------
REFERENCES
U.S. EPA. 1991a. Engineering Bulletin: Air Stripping of Aqueous Solutions. EPA/540/2-91/022.
U.S. Environmental Protection Agency, Office of Research and Development, Risk Reduction
Engineering Laboratory, Cincinnati, OH.
U.S. EPA. 1991b. Engineering Bulletin: In Situ Soil Vapor Extraction Treatment. EPA/540/2-
91/006. U.S. Environmental Protection Agency, Office of Research and Development, Risk
Reduction Engineering Laboratory, Cincinnati, OH.
U.S. EPA. 1991c. Engineering Bulletin: In Situ Steam Extraction Treatment. EPA/540/2-91/005.
U.S. Environmental Protection Agency, Office of Research and Development, Risk Reduction
Engineering Laboratory, Cincinnati, OH.
U.S. EPA. 1992a. A Citizen's Guide to Air Sparging: Technology Fact Sheet. EPA/542/F-
92/010. U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response,
Technology Innovation Office, Washington, DC.
U.S. EPA. 1992b. A Technology Assessment of Soil Vapor Extraction and Air Sparging.
EPA/600/R-92/173. U.S. Environmental Protection Agency, Office of Research and Development,
Risk Reduction Engineering Laboratory, Cincinnati, OH.
Volatilization 16 7/95
-------
f/EPA
flpCfK''
•-- ' _>fr'-, fc"* ** ,
.Envtronmental Protection'* '-*
Oovotoproent
_,* Superfund
EPA/540/2-91/Q22
October 1991
•c,
.V*"
Engineering Bulletin;
Air Stripping of Aqueous
Solutions
-------
Table 1
Effectiveness of Air Stripping on General Contaminant
Groups from Water
Contaminant Croups
w
1
?
o
1
f
1
i
Halogenated volatiles
Halogenated semivolatiles *
Nonhalogenated volatiles
Nonhalogenated semivolatiles
PCBs
Pesticides
Dioxins/Furans
Organic cyanides
Organic corrosives
Volatile metals
Nonvolatile metals
Asbestos
Radioactive materials
Inorganic corrosives
Inorganic cyanides
Oxidizers
Reducers
Effectiveness
•
V
•
Q
Q
Q
0
Q
Q
Q
Q
. a
a
a
a
a
Q
• Demonstrated Effectiveness: Successful treatability test at some scale
completed
T Potential Effectiveness: Expert opinion that technology will work
Q No Expected Effectiveness: Expert opinion that technology will not
work
• Only some compounds in this category are candidates for air strip-
ping.
where no information was available. The proven effectiveness
of the technology for a particular site or contaminant does
not ensure that it will be effective at all sites or that the
treatment efficiencies achieved will be acceptable at other
sites. For the ratings used for this table, demonstrated effec-
tiveness means that, at some scale, treatability testing dem-
onstrated the technology was effective for that particular
contaminant group. The ratings of potential effectiveness
and no expected effectiveness are both based upon expert
judgment. Where potential effectiveness is indicated, the
technology is believed capable of successfully treating the
contaminant group in a particular matrix. When the tech-
nology is not applicable or will probably not work for a
particular contaminant group, a no-expected-effectiveness
rating is given.
Limitations
Because air stripping of aqueous solutions is a means of
mass transfer of contaminants from the liquid to the air stream,
air pollution control devices are typically required to capture or
destroy contaminants in the offgas [8]. Even when offgas treat-
ment is required, air stripping usually provides significant ad-
vantages over alternatives such as direct carbon adsorption
from water because the contaminants are more favorably sorbed
onto activated carbon from air than from water. Moreover,
contaminant destruction via catalytic oxidation or incineration
may be feasible when applied to the offgas air stream.
Aqueous solutions with high turbidity or elevated levels
of iron, manganese, or carbonate may reduce removal effi-
ciencies due to scaling and the resultant channeling effects.
Influent aqueous media with pHs greater than 11 or less than
5 may corrode system components and auxiliary equipment.
The air stripper may also be subject to biological fouling. The
aqueous solution being air stripped may need pretreatment to
neutralize the liquid, control biological fouling, or prevent
scaling [6][9].
Contaminated water with VOC or semivolatile concentra-
tions greater than 0.01 percent generally cannot be treated by
air stripping. Even at lower influent concentrations, air strip-
ping may not be able to achieve cleanup levels required at
certain sites. For example, a 99 percent removal of
trichloroethene (TCE) from groundwater containing 100 parts
per million (ppm) would result in an effluent concentration of
1 ppm, well above drinking water standards. Without heating,
only volatile organic contaminants with a dimensionless Henry's
Law constant greater than 102 are amenable to continuous-
flow air stripping in aqueous solutions [6][5]. In certain cases,
where a high removal efficiency is not required, compounds
with lower Henry's Law constants may be air stripped. Ashworth
et al. published the Henry's Law constants for 45 chemicals
[10, p. 25]. Nirmalakhandan and Speece published a method
for predicting Henry's Law constants when published constants
are unavailable [11 ]. Air strippers operated in a batch mode
may be effective for treating water containing either high
contaminant concentrations or contaminants with lower Henry's
Law constants. However, batch systems are normally limited
to relatively low average flow rates.
Several environmental impacts are associated with air strip-
ping. Air emissions of volatile organic* are produced and must
be treated. The treated wastewater may need additional treat-
ment to remove metals and nonvolatiles. Deposits, such as
metal (e.g., iron) precipitates may occur, necessitating periodic
cleaning of air-stripping towers [6, p. 5-5]. In cases where
heavy metals are present and additional treatment will be re-
quired, it may be beneficial to precipitate those metals prior to
air stripping.
Technology Description
Air stripping is a mass transfer process used to treat ground-
water or surface water contaminated with volatile or semivola-
tile organic contaminants. At a given site, the system is de-
signed based on the type of contaminant present, the
contaminant concentration, the required effluent concentra-
tion, water temperature, and water flow rate. The major design
variables are gas pressure drop, air-to-water ratio, and type of
packing. Given those design variables, the gas and liquid
loading (i.e., flows per cross-sectional area), tower diameter
and packing height can be determined. Flexibility in the system
design should allow for changes in contaminant concentration,
air and water flow rates, and water temperature. Figure 1 is a
schematic of a typical process for the air stripping of contami-
nated water.
-------
Figure 1
Schematic Diagram of Air-Stripping System [8, p. 20][13, p. 43]
OFFGAS TREATMENT
(5)
": Stripper
• Offgas
Gas
Liquid
Stock
Contaminated
Gtoundwater
or
Surface Water
PRE-
TREATMENT
STORAGE
TANKS
(1)
Pump
Miit Eliminator
Pocked Bed
Air
\Blower
Recycle (optional)
In an air-stripping process, the contaminated liquid is
pumped from a groundwater or surface water source. Water to
be processed is directed to a storage tank (1) along with any
recycle from the air-stripping unit
Air stripping is typically performed at ambient temperature.
In some cases, the feed stream temperature is increased in a heat
exchanger (2). Heating the influent liquid increases air-stripping
efficiency and has been used to obtain a greater removal of semi-
volatile organics such as ketones. At temperatures close to 100°C,
steam stripping may be a more practical treatment technique [8,
p. 3].
The feed stream (combination of the influent and recycle)
is pumped to the air stripper (3). Three basic designs are used
for air strippers: surface aeration, diffused-air systems, and
specially designed liquid-gas contactors [4, p. 3]. The first two
of these have limited application to the treatment of contami-
nated water due to their lower contaminant removal efficiency.
In addition, air emissions from surface-aeration and diffused-air
systems are frequently more difficult to capture and control.
These two types of air strippers will not be discussed further.
The air stripper in Figure 1 is an example of a liquid-gas
contactor.
The most efficient type of liquid-gas contactor is the packed
tower [4, p. 3]. Within the packed tower, structures called
packing provide surface area on which the contaminated water
can form a thin film and come in contact with a countercurrent
flow of air. Air-to-water ratios may range from 10:1 to 300:1 on
a volumetric basis [14, p. 8]. Selecting packing material that
will maximize the wetted surface area will enhance air strip-
ping. Packed towers are usually cylindrical and are filled with
either random or structured packing. Random packing consists
of pieces of packing dumped onto a support structure within
the tower. Metal, plastic, or ceramic pieces come in standard
sizes and a variety of shapes. Smaller packing sizes generally
increase the interracial area for stripping and improve the mass-
Treated Liquid
transfer kinetics. However, smaller packing sizes result in an
increased pressure drop of the air stream and an increased
potential for precipitate fouling. Tripacks*, saddles, and slotted
rings are the shapes most commonly used for commercial
applications. Structured packing consists of trays fitted to the
inner diameter of the tower and placed at designated points
along the height of the tower. These trays are made of metal
gauze, sheet metal, or plastic. The choice of which type of
packing to use depends on budget and design constraints. Ran-
dom packing is generally less expensive. However, structured
packing reportedly provides advantages such as lower pressure-
drop and better liquid distribution characteristics [4, p. 5].
The processed liquid from the air-stripper tower may con-
tain trace amounts of contaminants. If required, this effluent is
treated (4) with carbon adsorption or other appropriate
treatments.
The offgas can be treated (5) using carbon adsorption,
thermal incineration, or catalytic oxidation. Carbon adsorption
is used more frequently than the other control technologies
because of its ability to remove hydrocarbons cost-effectively
from dilute (< 1 percent) air streams [8, p. 5].
Process Residuals
The primary process residual streams created with air-
stripping systems are the offgas and liquid effluent. The offgas
is released to the atmosphere after treatment; activated carbon
is the treatment most frequently applied to the offgas stream.
Where activated carbon is used, it is recommended that the
relative humidity of the air stream be reduced. Once spent, the
carbon can be regenerated onsite or shipped to the original
supplier for reactivation. If spent carbon is replaced, it may
have to be handled as a hazardous waste. Catalytic oxidation
and thermal incineration also may be used for offgas treatment
[15, p. 10] [8, p. 5]. Sludges, such as iron precipitates, build up
Engineering Bulletin: Air Stripping of Aqueous Solutions
-------
within the tower and must be removed periodically [6, p. 5-5].
Spent carbon can also result if carbon filters are used to treat
effluent water from the air-stripper system. Effluent water
containing nonvolatile contaminants may need additional treat-
ment Such liquids are treated onsite or stored and removed to
an appropriate facility. Biological, chemical, activated carbon,
or other appropriate treatment technologies may be used to
treat the effluent liquid. Once satisfactorily treated, the water is
sent to a sewage treatment facility, discharged to surface water,
or returned to the source, such as an underground aquifer.
Site Requirements
Air strippers are most frequently permanent installations,
although mobile systems may be available for limited use.
Permanent installations may be fabricated onsite or may be
shipped in modular form and constructed onsite. Packing is
installed after fabrication or construction of the tower. A concrete
pad will be required to support the air-stripper tower in either
case. Access roads or compacted soil will be needed to transport
the necessary materials.
Standard 440V, three-phase electrical service is needed.
Water should be available at the site to periodically clean scale
or deposits from packing materials. The quantity of water
needed is site specific. Typically, treated effluent can be used to
wash scale from packing.
Contaminated liquids are hazardous, and their handling
requires that a site safety plan be developed to provide for
personnel protection and special handling measures. Spent
activated carbon may be hazardous and require similar han-
dling. Storage may be needed to hold the treated liquid until it
has been tested to determine its acceptability for disposal or
release. Depending upon the site, a method to store liquid that
has been pretreated may be necessary. Storage capacity will
depend on liquid volume.
Onsite analytical equipment for conducting various analy-
ses, including gas chromatography capable of determining
site-specific organic compounds for performance assessment,
make the operation more efficient and provide better informa-
tion for process control.
Performance Data
System performance is measured by comparing contami-
nant concentrations in the untreated liquid with those in the
treated liquid. Performance data on air-stripping systems, rang-
ing from pilot-scale to full-scale operation, have been reported
by several sources, including equipment vendors. Data ob-
tained on air strippers at Superfund sites also are discussed
below. The data are presented as originally reported in the
referenced documents. The quality of this information has not
been determined. The key operating and design variables are
provided when they were available in the reference.
An air-stripping system, which employed liquid-phase CAC
to polish the effluent, was installed at the Sydney Mine site in
Valrico, Florida. The air-striooing tower was 4 feet in diameter,
Table 2
Performance Data for the Groundwater Treatment
System at the Sydney Mine Site, FL [13, p. 42]
Concentration
Contaminant
Volatile organia
Benzene
Chlorobenzene
1,1-dichloroe thane
Trans-1 ,2-dichloropropane
Ethyl benzene
Methyiene chloride
Toluene
Trichlorofluorometriane
Meta-xylene
Ortrto-xylene
Extractable organks
3-0,1-dimethylethyl) phenol
Pesticides
2,4-D
2,4,5-TP
Inorganic
Iron (mg/L)
Influent
6&L)
11
1
39
1
5
503
10
71
3
2
32
4
1
11
Effluent
(W/L)
ND*
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
<0.03
•ND = Not detected at method detection limit of 1 ng/L for volatile
organic: and 10 ng/L for extractable organic and pesticides
42 feet tall, and contained a 24-foot bed of 3.5-inch diameter
polyethylene packing. The average design water flow was 150
gallons per minute (gpm) with a hydraulic loading rate of 12
gpm/ft2 and a volumetric air-to-water ratio of approximately
200:1. The air-stripping tower was oversized for use at future
treatment sites. Effluent water from the air stripper was pol-
ished in a carbon adsorption unit Table 2 summarizes the
performance data for the complete system; it is unclear how
much removal was accomplished by the air stripper and how
much by the activated carbon. Influent concentrations of
total organics varied from approximately 25 parts per billion
(ppb)to700ppb[13, p. 41].
Air stripping was used at well 12A in the city of Tacoma,
Washington. Well 12A had a capacity of 3,500 gpm and was
contaminated with chlorinated hydrocarbons, including 1,1,2,2-
tetrachloroethane; trans-1,2-dichloroethene (DCE); TCE; and
perchloroethylene. The total VOC concentration was approxi-
mately 100 ppb. Five towers were installed and began operation
on July 15,1983. Each tower was 12 feet in diameter and was
packed with 1-inch polypropylene saddles to a depth of 20
feet The water flow rate was 700 gpm for each tower, and the
volumetric air-to-water ratio was 310:1. The towers consis-
tently removed 94 to 98 percent of the influent 1,1,2,2-
tetrachloroethane with an overall average of 95.5 percent re-
moval. For the other contaminants, removal efficiencies in excess
of 98 percent were achieved [16, p. 112].
Another remedial action site was Wurtsmith Air Force Base
in Oscoda, Michigan. The contamination at this site was the
result of a leaking underground storage tank near a mainte-
-------
TobteJ
Air-Stripper Performance Summary
AtWurtsmlthAFB
[17, p. 121]
G/l
(vol)
10
10
10
18
18
18
25
25'
25
Water Flow
(L/mln)
1,135
1,700
2,270
1,135
1,700
2,270
1,135
1,700
2,270
Single Tower
(% Removed)
95
94
86
98
97
90
98
98
98
Series Operation
(% Removed)
99.8
99.8
96.0
99.9
99.9
99.7
99.9
99.9
99.9
Influent TCE concentration: 50-8,000 jig/L Water temperature: 283°K
nance facility. Two packed-tower air strippers were installed to
remove TCE. Each tower was 5 feet in diameter and 30 feet tall,
with 18 feet of 16mm pall ring packing. The performance
summary for the towers, presented in Table 3, is based on
evaluations conducted in May and August 1982 and January
1983. Excessive biological growth decreased performance and
required repeated removal and cleaning of the packing. Op-
eration of the towers in series, with a volumetric air-to-water
ratio of 25:1 and a water flow of 600 gpm (2,270 U/min),
removed 99.9 percent of the contaminant [17, p. 119].
A 2,500 gpm air stripper was used to treat contaminated
groundwater during the initial remedial action at the Verona
Well field site in Battle Creek, Michigan. This well field is the
major source of public potable water for the city of Battle Creek.
The air stripper was a 10-foot diameter tower packed to a
height of 40 feet with 3.5 inch pall rings. The air stripper was
operated at 2,000 gpm with a 20:1 volumetric air-to-water
ratio. Initial problems with iron oxide precipitating on the
packed rings were solved by recirculating sodium hypochlorite
through the stripper about four times per year [8, p. 8-9]. The
total VOC concentration of 131 ppb was reduced by approxi-
mately 82.9 percent [15, p. 56]. The air stripper offgas was
treated via vapor phase granular activated carbon beds. The
offgas was heated prior to entering the carbon beds to reduce
its humidity to 40 percent
An air stripper is currently operating at the Hyde Park
Superfund site in New York. Treatek, Inc. which operates the
unit, reports the system is treating about 80,000 gallons per
day (gpd) of landfill leachate. The contaminants are in the
range of 4,000 ppm total organic carbon (TOQ. The air
stripper is reportedly able to remove about 90 percent of the
TOCs [18]. A report describing the performance of the air
stripper is expected to be published during 1991.
The primary VOCs at the Des Moines Superfund site were
TCE; 1,2-DCE; and vinyl chloride. The TCE initial concentration
was approximately 2,800 ppb and gradually declined to the
800 to 1,000 ppb range after 5 months. Initial groundwater
concentrations of 1,2-DCE were unreported while the concen-
tration of vinyl chloride ranged from 38 ppb down to 1 ppb.
The water flow rate to the air stripper ranged from 500 to 1,850
gpm and averaged approximately 1,300 gpm. No other design
data were provided. TCE removal efficiencies were generally
above 96 percent, while the removal efficiencies for 1,2-DCE
were in the 85 to 96 percent range. No detectable levels of vinyl
chloride were observed in the effluent water [12, p. B-l ].
VOCs were detected in the Eau Claire municipal well field in
Eau Claire, Wisconsin, as part of an EPA groundwater supply
survey in 1981. An air stripper was placed on-line in 1987 to
protect public health and welfare until completion of the reme-
dial investigation/feasibility study (RI/FS) and final remedy selec-
tion. Data reported on the Eau Claire site were for the period
beginning August 31,1987 and ending February 15,1989. Dur-
ing this period, the average removal efficiency was greater than
Table 4
Air-Stripper Performance at
Eau Claire Municipal Well Reid [12, p. C-1]
Contaminant
1 ,1 -Dichloroethene
1,1-Dichloroethane
1,1,1-Trichloroethane
Tridiloroethene
Influent
Concentration
(Ppb)
0.17-2.78
0.38-1.81
4.32-14.99
2.53-11.18
Rttnovol
Efficiency
(*)
88
93
99
98
88 percent for the four chlorinated organic compounds studied.
The average removal efficiencies are shown in Table 4. The air
stripper had a 12-foot diameter and was 60 feet tall, with a
packed bed of 26 feet Water feed rates were approximately 5 to
6 million gallons per day (mgd). No other design parameters
were reported [12, p. C-1].
In March 1990, an EPA study reviewed the performance
data from a number of Superfund sites, including the Brewster
Well Field, Hicksville MEK Spill, Rockaway Township, Western
Processing, and Cilson Road Sites [15].
Reported removal efficiencies at the Brewster Well Field site
in New York were 98.50 percent, 93.33 percent, and 95.59
percent for tetrachloroethene (PCE); TCE; and 1,2-DCE; respec-
tively. Initial concentrations of the three contaminants were
200 ppb (PCE), 30 ppb (TCE) and 38 ppb (1,2-DCE) [15, p. 55].
The 300 gpm air stripper had a tower diameter of 4.75 feet,
packing height of 17.75 feet, air-to-water ratio of 50:1, and
used 1 -inch saddles for packing material [15, p. 24].
A removal efficiency of 98.41 percent was reported for methyl
ethyl ketone (MEK) at the Hicksville MEK spill site in New York.
The reported influent MEK concentration was 15 ppm. The air
stripper had a 100 gpm flowrate, an air-to-water ratio of 120:1, a
tower diameter of 3.6 feet, a packing height of 15 feet, and used
2-inch jaeger Tripack packing material. Water entering the air
stripper was heated to approximately 180°to195°F by heat ex-
changers [15, p. 38].
Engineering Bulletin: Air Stripping of Aqueous Solutions
-------
Table 5
Air Stripper Performance at Rockaway
Township. NJ [IS, p. 53]
Contaminant Influent
Concentration
(ppt»
Trichloroethylene
Methyl-tert-butyl ether
1,1-Dichloroethylene
cis-1 ,2-Dichloroethylene
Chloroform
1,1,1 -Trichloroethane
1,1-Oichloroethane
Total VOC
28.3
3.2
4.0
6.4
1.3
20.0
2.0
65.2
Removal
Efficiency
(%)
99.99
99.99
99.99
99.99
99.99
99.99
99.99
99.99
Table 7
Air-Stripper Performance at the
Gilson Road Site, NH [15, p. 65]
Contaminant
Isopropyl alcohol
Acetone
Toluene
Oichloromethane
1,1,1 -Trichloroethane
Trichloroethylene
Chloroform
Total VOC
Influent
Concentration
(fob)
532
473
14,884
236
1.340
1,017
469
18,951
Average Removal
Efficiency
(%)
95.30
91.93
99.87
93.79
99.45
99.71
99.06
99.41
The Rockaway Township air stripper had a flowrate of
1,400 gpm, tower diameter of 9 feet, packing height of 25
feet, air-to-water ratio of 200:1, and used 3-inch Tellerettes
packing material. The performance data are shown in Table 5
[15, p. 18].
The Western Processing site had two air-stripping towers
treating different wells in parallel. The first tower had a 100
gpm (initial) and 200 gpm (maximum) flowrate, a tower diam-
eter of 40 feet, a packing height of 40.5 feet, an air-to-water
ratio of 160:1 (initial) and 100:1 (maximum), and used 2-inch
jaeger Tripack packing material. The second tower had a 45
Tabled
Air-Stripper Performance at
Western Processing, WA [15, p. 61]
Contaminant
Benzene
Carbon tetrachloride
Chloroform
1 ,2-Dichloroethane
1 ,1 -Dichloroethylene
1,1,1 -Trichloroethane
Trichloroethylene
Vinyl chloride
Oichloromethane
Tetrachloroethylene
Toluene
1 ,2-Dichlorobenzene
Hexachlorobutadiene
Hexachloroethane
Isobutanol
Methyl ethyl ketone
Influent
Concentration
(ppb)
73
5
781
22
89
1,440
8,220
159
8,170
378
551
11
250
250
10
1,480
Removal
Efficiency
<%)
93.15
—
99.36
77.27
94.38
99.65
99.94
99.37
99.63
98.68
99.09
54.55
96.00
96.00
0.00
70.27
gpm (initial) and 60 gpm (maximum) flowrate, a tower diam-
eter of 2 feet, packing height of 22.5 feet, air-to-water ratio of
83.1:1 (initial) and 62.3:1 (maximum), and used 2-inch Jaeger
Tripack packing material [15, p. 31]. The performance data are
presented in Table 6.
The Gilson Road Site used a single column high-tempera-
ture air stripper (HTAS) which had a 300 gpm flowrate (heated
influent), tower diameter of 4 feet, packing height of 16 feet, air-
to-water ratio of 51.4:1, and used 16 Koch-type trays at 1-foot
intervals [15, p. 42-45]. The performance data are provided in
Table 7. Due to the relatively high influent concentration and
the high (average) removal efficiency, this system required supple-
mental control of the volatiles in the offgas.
Another EPA study, completed in August 1987, analyzed
performance data from 177 air-stripping systems in the United
States. The study presented data on systems design, contami-
nant types, and loading rates, and reported removal efficiencies
for 52 sites. Table 8 summarizes data from 46 of those sites,
illustrating experiences with a wide range of contaminants [19].
Reported efficiencies should be interpreted with caution. Low
efficiencies reported in some instances may not reflect the true
potential of air stripping, but may instead reflect designs in-
tended to achieve only modest removals from low-level con-
taminant sources. It is also important to recognize that, be-
cause different system designs were used for these sites, the
results are not directly comparable from site to site.
Technology Status
Air stripping is a well-developed technology with wide
application. During 1988, air stripping of aqueous solutions
was a part of the selected remedy at 30 Superfund sites [1]. In
1989, air stripping was a part of the selected remedy at 38
Superfund Sites [2].
The factors determining the cost of an air stripper can be
categorized as those affecting design, emission controls, and
operation and maintenance (O&M). Design considerations such
as the size and number of towers, the materials of construction,
and the desired capacity influence the capital costs. Equipment
cost components associated with a typical packed-tower air strip-
-------
Tables
Summary of Reported Air-Stripper Removal Efficiencies from 46 Sites [19]
Contaminant
Aniline
Benzene
Bromodichloromethane
Bromoform
Chloroform
Chlorobenzene
Dibromochloromethane
Dichloroethylene
Diisopropyl ether
Ethyl benzene
Ethylene dichloride
Methytene chloride
Methyl ethyl ketone
2-Methylphenol
Methyl tertiary butytether
Perchloroethylene
Phenol
1 ,1 ,2,2-Tetrachloroethane
Trichloroethane
Trichloroethylene
1 ,2,3-Trichloropropane
Toluene
Xylene
Volatile organic compounds
Total Volatile Organic:
No. of
Data Points
1
3
1
1
1
0
1
7
2
1
7
1
1
1
2
17
1
1
8
34
1
2
4
3
46
Influent
Concentration
(W/D
Average
226
3,730
36
8
530
95
34
409
35
6,370
173
15
100
160
90
355
198
300
81
7,660
29,000
6,710
14,823
44,000
11,120
Range
NA»
200-10,000
NA
MA
1500
NA
NA
2-3,000
20-50
100-1,400
5-1,000
9-20
NA
NA
50-130
3-4,700
NA
NA
5-300
1-200,000
NA
30-23,000
17-53,000
57-130,000
12-205,000
Reported
Removal efficiency*
(*>)
Average
58
99.6
81
44
48
Nty
60
98.6
97.0
99.8
99.3
100
99
70
97.0
96 .5
74
95
95.4
98.3
99
98
98.4
98.8
97.5
Range
NA
99-100
NA
NA
NA
ND
NA
96-100
95-99
NA
79-100
NA
NA
NA
95-99
86-100
NA
NA
70-100
76-100
NA
96-100
96-100
98-99.5
58.1-100
•Note that the averages and ranges presented in this column represent more data points than are presented in the second column of this table because the
removal efficiencies were not available for all air strippers.
IMA » Not Applicable. Data available for only one stripper.
•ND- No Data. Insufficient data available.
Figure 2
Cost Estimates for Air Stripping without Air Emission
Controls as a Function of the Henry's Law Coefficient
».^_..^_
0.1 mgd
1mgd
10 mgd
0.006 0.01
per include tower shell, packing support, water distributor, mist
eliminator, packing, blower and motor, engineering, and con-
tractor overhead and profit The addition of an air treatment
system roughly doubles the cost of an air-stripping system [3][6,
p. 5-5). Onsite regeneration or incineration of carbon may
increase the cost associated with emission controls. The primary
O&M cost components are operating labor, repair and upkeep,
and energy requirements of blower motor and pumps [12].
Adams et at. made cost estimates based on flows from 0.1 to
10 mgd assuming a removal efficiency of 99 percent The
process was optimized for packed tower volume and energy
consumption. Figure 2 presents general cost curves for three
flow rates based on their work. Air emissions controls were not
included in the costs. Within the range of Henry's Law Coefficients
of 0.01 to 1.0, the cost ranged from JO.07/1,000 gallons to
$0.70/1,000 gallons. As the Henry's Law Coefficient approached
0.005, the costs rapidly rose to $7.00/1,000 gallons [20, p. 52].
Henrys Coefficient
(dimensionless)
Engineering Bulletin: Air Stripping of Aqueous Solutions
-------
According to Hydro Group, Inc., the cost of air stripping
may range from $0.04 to $0.17 per 1,000 gallons [21, p. 7].
The Des Moines Superfund site unit cost for groundwater treat-
ment is estimated to be about $0.45/1,000 gallons based on a
1,250 gpm treatment rate and an average O&M cost of
$200,000/year for 10 years at 10 percent interest The Eau
Claire site had a unit cost of roughly $0.14/1,000 gallons
assuming a 5-year operation period and an average treat-
ment rate of 7 million gpd [12, p. C-6].
Recent developments in this technology include high-
temperature air stripping (HTAS) and rotary air stripping. A
full-scale HTAS system was demonstrated at McClellan AFB to
treat groundwater contaminated with fuel and solvents from
spills and storage tank leaks. The combined recycle and makeup
was heated to 65°C, and a removal efficiency of greater than
99 percent was achieved [8, p. 9]. The rotary design, marketed
under the name HIGEE, was demonstrated at a U.S. Coast
Guard air station in East Bay Township, Michigan. At a gas-to-
liquid ratio of 30:1 and a rotor speed of 435 rpm, removal
efficiencies for all contaminants, except 1,2-OCE, exceeded 99
percent The removal efficiency for 1,2-DCE was not reported
[4, p. 19].
Raising influent liquid temperature increases mass-transfer
rates and the Henry's Law Constants. This results in improved
removal efficiencies for VOCs and the capability to remove
contaminants that are less volatile. Table 9 illustrates the
influence that changes in liquid temperature have on contami-
nant removal efficiencies. Note that steam stripping may be
the preferred treatment technology at a feed temperature
approaching 100°C, because the higher temperatures associ-
ated with steam stripping allow organics to be removed more
efficiently than in HTAS systems. However, steam stripping
uses more fuel and therefore will have higher operating costs.
Additionally, the capital costs for steam stripping may be higher
than for HTAS if higher-grade construction materials are needed
at the elevated temperatures used in steam stripping [8, p. 3].
Table 9
Influence of Feed Temperature on Removal of Water
Soluble Compounds from Groundwater [8, p. 15]
Compound
2 • Propanol
Acetone
Tetrahydrofuran
Percent Removed at Selected Temperature
IfC 3fC 73-C
10
35
SO
23
80
92
70
95
>99
Rotary air strippers use centrifugal force rather than gravity
to drive aqueous solutions through the specially designed pack-
ing. This packing, consisting of thin sheets of metal wound
together tightly, was developed for rotary air strippers because of
the strain of high centrifugal forces. The use of centrifugal force
reportedly results in high removal efficiencies due to formation of
a very thin liquid film on wetted surfaces. The rotary motion also
causes a high degree of turbulence in the gas phase. The
turbulence results in improved liquid distribution over conven-
tional gravity-driven air strippers. The biggest advantage of
rotary strippers is the high capacity for a relatively small device.
Disadvantages include the potential for mechanical failures and
additional energy requirements for the drive motor. Water
carryover into the air effluent stream may cause problems with
certain emission control devices used to treat the contaminated
air. Cost and performance data on rotary air strippers are very
limited [4, p. 16].
EPA Contact
Technology-specific questions regarding air stripping of
liquids may be directed to:
Dr. James Heidman
U.S. Environmental Protection Agency
Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Gndnnati, Ohio 45268
FTS 684-7632
(513) 569-7632
Acknowledgments
This bulletin was prepared for the U.S. Environmental Pro-
tection Agency, Office of Research and Development (ORD),
Risk Reduction Engineering Laboratory (RREL), Cincinnati, Ohio,
by Science Applications International Corporation (SAIQ under
contract No. 68-C8-0062. Mr. Eugene Harris served as the EPA
Technical Project Monitor. Mr. Gary Baker was SAICs Work
Assignment Manager. This bulletin was authored by Mr. Jim
Rawe of SAJC. The Author is especially grateful to Mr. Ron
Turner, Mr. Ken Dostal and Dr. James Heidman of EPA, RREL,
who have contributed significantly by serving as technical con-
sultants during the development of this document
The following other Agency and contractor personnel have
contributed their time and comments by participating in the
expert review meeting and/or peer reviewing the document
Mr. Ben Blaney
Dr. John Crittenden
Mr. Clyde Dial
Dr. James Gossett
Mr. George Wahl
Ms. Tish Zimmerman
EPA-RREL
Michigan Technological University
SAIC
Cornell University
SAIC
EPA-OERR
EnaiaeerinaBulletir^AJ^StTipping of Aou&ous Solutions,
-------
REFERENCES
1. ROD Annual Report, FY 1988. EPA/540/8-89/006, U.S.
Environmental Protection Agency, 1989.
2. ROD Annual Report, FY 1989. EPA/540/8-90/006, U.S.
Environmental Protection Agency, 1990.
3. Lenzo, F., and K. Sullivan. Ground Water Treatment
Techniques: An Overview of the State-of-the-Art in America.
Presented at the First US/USSR Conference on
Hydrogeology, Moscow, July 3-5,1989.
4. Singh, S.P., and R.M. Counce. Removal of Volatile Organic
Compounds From Croundwater: A Survey of the Technolo-
gies. Prepared for the U.S. Department of Energy, under
Contract DE-AC05-84OR21400,1989.
5. Handbook; Remedial Acton at Waste Disposal Sites (Re-
vised). EPA/625/6-85/006, U.S. Environmental Protection
Agency, Washington, D.C, pp.10-48 through 10-52,1985.
6. Mobile Treatment Technologies For Superfund Wastes.
EPA/540/2-86/003(f), U.S. Environmental Protection
Agency, Washington, D.C., pp. 5-3 through 5-6,1986.
7. Technology Screening Guide for Treatment of CERCLA Soils
and Sludges. EPA/540/2-88/004, U.S. Environmental
Protection Agency, 1988.
8. Blaney, B.L, and M. Branscome. Air Strippers and their
Emissions Control at Superfund Sites. EPA/600/D-88/153,
U.S. Environmental Protection Agency, Gncinnati, Ohio,
1988.
9. Umphres, M.D., and J.H. Van Wagner. An Evaluation of the
Secondary Effects of Air Stripping. EPA/600/S2-89/005, U.S.
Environmental Protection Agency, Cincinnati, Ohio, 1990.
10. Ashworth, R. A., G. B. Howe, M. E. Mullins and T. N.
Rogers. Air-Water Partitioning Coefficients of Organics in
Dilute Aqueous Solutions, journal of Hazardous Materials,
18:25-36,1988.
11. Nirmalakhandan, N. N. and R. E. Speece. QSAR Model for
Predicting Henry's Constants. Environmental Science and
Technology, 22:1349-1357,1988.
12. Young, C, et al. Innovative Operational Treatment
Technologies for Application to Superfund Site- Nine
Case Studies. EPA/540/2-90/006, U.S. Environmental
Protection Agency, Washington, D.C., 1990.
13. Mclntyre, G.T., et al. Design and Performance of a
Groundwater Treatment System for Toxic Organics
Removal, journal WPCF, 58(1):41-46,1986.
14. A Compendium of Technologies Used in the Treatment
of Hazardous Wastes. EPA/625/8-87/014, U.S.
Environmental Protection Agency, Cincinnati, Ohio,
1987.
15. Air/Superfund National Technical Guidance Study
Series: Comparisons of Air Stripper Simulations and
Field Performance Data. EPA/450/1-90/002, U.S.
Environmental Protection Agency, 1990.
16. Byers, W.D., and CM. Morton. Removing VOC from
Groundwater; Pilot, Scale-up, and Operating Experi-
ence. Environmental Progress, 4(2):112-118,1985.
17. Gross, R.L, and S.G. TerMaath. Packed Tower Aeration
Strips Trichloroethylene from Groundwater. Environ-
mental Progress, 4(2):119-124,1985.
18. Personal communication with vendor.
19. Air Stripping of Contaminated Water Sources - Air
Emissions and Controls. EPA/450/3-87/017, U.S.
Environmental Protection Agency, 1987.
20. Adams, j. Q. and R. M. Clark. Evaluating the Costs of
Packed-Tower Aeration and GAC for Controlling
Selected Organics. Journal AWWA, 1:49-57,1991.
21. Leruo, F.C. Air Stripping of VOCs from Groundwater.
Decontaminating Polluted Water. Presented at the
49th Annual Conference of the Indiana Water Pollution
Control Association, August 19-21,1985.
Engineering Bulletin: Air Stripping of Aqueous Solutions
-------
United States Center for Environmental Research BULK RATE
Environmental Protection Information POSTAGE & FEES PAID
Agency Gncinnati, OH 45268 EPA
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v>EPA
United States
Environmental Protection
Agency
Office of Emergency and
Remedial Response
Washington, DC 20460
Office of
Research and Development
Cincinnati, OH 45268
Superfund
EPA/540/2-91/006
May 1991
Engineering Bulletin
In Situ Soil Vapor Extraction
Treatment
Purpose
Section 121(b) of the Comprehensive Environmental Re-
sponse, Compensation, and Liability Act (CERCLA) mandates
the Environmental Protection Agency (EPA) to select remedies
that "utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the maxi-
mum extent practicable" and to prefer remedial actions in
which treatment "permanently and significantly reduces the
volume, toxicity, or mobility of hazardous substances, pollut-
ants, and contaminants as a principal element" The Engi-
neering Bulletins are a series of documents that summarize
the latest information available on selected treatment and site
remediation technologies and related issues. They provide
summaries of and references for the latest information to help
remedial project managers, on-scene coordinators, contrac-
tors, and other site cleanup managers understand the type of
data and site characteristics needed to evaluate a technology
for potential applicability to their Superfund or other hazard-
ous waste site. Those documents that describe individual
treatment technologies focus on remedial scoping needs.
Addenda will be issued periodically to update the original
bulletins.
Abstract
Soil vapor extraction (SVE) is designed to physically re-
move volatile compounds, generally from the vadose or un-
saturated zone. It is an in situ process employing vapor
extraction wells alone or in combination with air injection
wells. Vacuum blowers supply the motive force, inducing air
flow through the soil matrix. The air strips the volatile com-
pounds from the soil and carries them to the screened ex-
traction well.
Air emissions from the systems are typically controlled by
adsorption of the volatiles onto activated carbon, thermal
destruction (incineration or catalytic oxidation), or condensa-
tion by refrigeration [1, p. 26].*
SVE is a developed technology that has been used in
commercial operations for several years. It was the selected
remedy for the first Record of Decision (ROD) to be signed
under the Superfund Amendments and Reauthorization Act
of 1986 (the Verona Well Field Superfund Site in Battle Creek,
* [reference number, page number]
Michigan). SVE has been chosen as a component of the ROD
at over 30 Superfund sites [2] [3] [4] [5] [6].
Site-specific treatability studies are the only means of
documenting the applicability and performance of an SVE
system. The EPA Contact indicated at the end of this bulletin
can assist in the location of other contacts and sources of
information necessary for such treatability studies.
The final determination of the lowest cost alternative will
be more site-specific than process equipment dominated.
This bulletin provides information on the technology applica-
bility, the limitations of the technology, the technology de-
scription, the types of residuals produced, site requirements,
the latest performance data, the status of the technology, and
sources for further information.
Technology Applicability
In situ SVE has been demonstrated effective for removing
volatile organic compounds (VOCs) from the vadose zone.
The effective removal of a chemical at a particular site does
not, however, guarantee an acceptable removal level at all
sites. The technology is very site-specific. It must be applied
only after the site has been characterized. In general, the
process works best in well drained soils with low organic
carbon content. However, the technology has been shown to
work in finer, wetter soils (e.g., clays), but at much slower
removal rates [7, p. 5].
The extent to which VOCs are dispersed in the soil-
vertically and horizontally—is an important consideration in
deciding whether SVE is preferable to other methods. Soil
excavation and treatment may be more cost effective when
only a few hundred cubic yards of near-surface soils have
been contaminated. If volume is in excess of 500 cubic yards,
if the spill has penetrated more than 20 or 30 feet, or the
contamination has spread through an area of several hundred
square feet at a particular depth, then excavation costs begin
to exceed those associated with an SVE system [8] [9]
[10, p. 6].
The depth to groundwater is also important. Croundwa-
ter level in some cases may be lowered to increase the volume
of the unsaturated zone. The water infiltration rate can be
Printed on Recycled Paper
-------
Table 1
Effectiveness of SVE on General
Contaminant Groups For Soil
Contaminant Croups
I
1
Halogenated volatiles
Halogenated semivolatiles
Nonhalogenated volatiles
Nonhalogenated semivolatiles
PCBs
Pesticides
Oioxins/Furans
Organic cyanides
Organic corrosives
Volatile metals
Nonvolatile metals
Asbestos
Radioactive materials
Inorganic corrosives
Inorganic cyanides
Oxidizers
Reducers
Effectiveness
Soil
m
V
•
•
Q
Q
Q
Q
Q
Q
Q
Q
Q
Q
Q
Q
V
• Demonstrated Effectiveness: Successful treatability test at some
scale completed
V Potential Effectiveness: Expert opinion that technology will work
Q No Expected Effectiveness: Expert opinion that technology will not
work
controlled by placing an impermeable cap over the site. Soil
heterogeneities influence air movement as well as the loca-
tion of chemicals. The presence of heterogeneities may make
it more difficult to position extraction and inlet wells. There
generally will be significant differences in the air permeability
of the various soil strata which will affect the optimum design
of the SVE facility. The location of the contaminant on a
property and the type and extent of development in the
vicinity of the contamination may favor the installation of an
SVE system. For example, if the contamination exists beneath
a building or beneath an extensive utility trench network, SVE
should be considered.
SVE can be used alone or in combination with other
technologies to treat a site. SVE, in combination with
groundwater pumping and air stripping, is necessary when
contamination has reached an aquifer. When the contamina-
tion has not penetrated into the zone of saturation (i.e.,
below the water table), it is not necessary to install a ground-
water pumping system. A vacuum extraction well will cause
the water table to rise and will saturate the soil in the area of
the contamination. Pumping is then required to draw the wa-
ter table down and allow efficient vapor venting [11, p. 169].
SVE may be used at sites not requiring complete remedia-
tion. For example, a site may contain VOCs and nonvolatile
contaminants. A treatment requiring excavation might be
selected for the nonvolatile contaminants. If the site required
excavation in an enclosure to protect a nearby populace from
VOC emissions, it would be cost effective to extract the volatiles
from the soil before excavation. This would obviate the need
for the enclosure. In this case it would be necessary to vent
the soil for only a fraction of the time required for complete
remediation.
Performance data presented in this bulletin should not be
considered directly applicable to other Superfund sites. A
number of variables such as the specific mix and distribution
of contaminants affect system performance. A thorough
characterization of the site and a well-designed and conducted
treatability study are highly recommended.
The effectiveness of SVE on general contaminant groups
for soils is shown in Table 1. Examples of constituents within
contaminant groups are provided in the "Technology Screen-
ing Guide For Treatment of CERCLA Soils and Sludges" [12].
This table is based on the current available information or
professional judgment where no information was available.
The proven effectiveness of the technology for a particular site
or waste does not ensure that it will be effective at all sites or
that the treatment efficiencies achieved will be acceptable at
other sites. For the ratings used in this table, demonstrated
effectiveness means that, at some scale, treatability tests showed
that the technology was effective for that particular contami-
nant and matrix. The ratings of potential effectiveness, or no
expected effectiveness are both based upon expert judgment
Where potential effectiveness is indicated, the technology is
believed capable of successfully treating the contaminant group
in a particular matrix. When the technology is not applicable
or will probably not work for a particular combination of
contaminant group and matrix, a no-expected-effectiveness
rating is given. Another source of general observations and
average removal efficiencies for different treatability groups is
contained in the Superfund Land Disposal Restrictions (LDR)
Guide #6A, "Obtaining a Soil and Debris Treatability Variance
for Remedial Actions," (OSWER Directive 9347.3-06FS, July
1989) [13] and Superfund LDR Guide #6B, "Obtaining a Soil
and Debris Treatability Variance for Removal Actions," (OSWER
Directive 9347.3-07FS, December 1989) [14].
Limitations
Soils exhibiting low air permeability are more difficult to
treat with in situ SVE. Soils with a high organic carbon
content have a high sorption capacity for VOCs and are more
difficult to remediate successfully with SVE. Low soil tem-
perature lowers a contaminant's vapor pressure, making vola-
tilization more difficult [11 ].
Sites that contain a high degree of soil heterogeneity will
likely offer variable flow and desorption performance, which
will make remediation difficult However, proper design of
the vacuum extraction system may overcome the problems of
heterogeneity [7, p. 19] [15].
Engineering Bulletin: In Situ Soil Vapor Extraction Treatment
-------
It would be difficult to remove soil contaminants with
low vapor pressures and/or high water solubilities from a site.
The lower limit of vapor pressure for effective removal of a
compound is 1 mm Hg abs. Compounds with high water
solubilities, such as acetone, may be removed with relative
ease from arid soils. However, with normal soils (i.e., mois-
ture content ranging from 10 percent to 20 percent), the
likelihood of successful remediation drops significantly be-
cause the moisture in the soil acts as a sink for the soluble
acetone.
Technology Description
Figure 1 is a general schematic of the in situ SVE process.
After the contaminated area is defined, extraction wells (1)
are installed. Extraction well placement is critical. Locations
must be chosen to ensure adequate vapor flow through the
contaminated zone while minimizing vapor flow through
other zones [11, p. 170]. Wells are typically constructed of
PVC pipe that is screened through the zone of contamination
[11]. The screened pipe is placed in a permeable packing; the
unscreened portion is sealed in a cement/bentonite grout to
prevent a short-circuited air flow direct to the surface. Some
SVE systems are installed with air injection wells. These wells
may either passively take in atmospheric air or actively use
forced air injection [9]. The system must be designed so that
any air injected into the system does not result in the escape
of VOCs to the atmosphere. Proper design of the system can
also prevent offsite contamination from entering the area
being extracted.
The physical dimensions of a particular site may modify
SVE design. If the vadose zone depth is less than 10 feet and
the area of the site is quite large, a horizontal piping system or
trenches may be more economical than conventional wells.
An induced air flow draws contaminated vapors and
entrained water from the extraction wells through headers—
usually plastic piping—to a vapor-liquid separator (2). There,
entrained water is separated and contained for subsequent
treatment (4). The contaminant vapors are moved by a
vacuum blower (3) to vapor treatment (5).
Vapors produced by the process are typically treated by
carbon adsorption or thermal destruction. Other methods—
such as condensation, biological degradation, and ultraviolet
oxidation—have been applied, but only to a limited extent.
Process Residuals
The waste streams generated by in situ SVE are vapor and
liquid treatment residuals (e.g., spent granular activated car-
bon [CAC]), contaminated groundwater, and soil tailings from
drilling the wells. Contaminated groundwater may be treated
and discharged onsite [12, p. 86] or collected and treated off-
site. Highly contaminated soil tailings from drilling must be
collected and may be either cleaned onsite or sent to an
offsite, permitted facility for treatment by another technology
such as incineration.
Site Requirements
SVE systems vary in size and complexity depending on
the capacity of the system and the requirements for vapor
and liquid treatment They are typically transported by vehicles
ranging from trucks to specifically adapted flatbed semitrailers;
therefore, a proper staging area for these vehicles must be
incorporated in the plans.
Figure 1
Process Schematic of the In Situ Soil Vapor Extraction System
Cl«an Air
Air V«nt or
ln|«ctlon Wall
Wit»r Tibl*
Engineering Bulletin: In Situ Soil Vapor Extraction Treatment
-------
Adequate access roads must be provided to bring mobile
drilling rigs onsite for construction of wells and to deliver
equipment required for the process (e.g., vacuum blowers,
vapor-liquid separator, emission control devices, CAC canisters).
A small commercial-size SVE system would require about
1,000 square feet of ground area for the equipment This
area does not include space for the monitoring wells which
might cover 500 square feet. Space may be needed for a
forklift truck to exchange skid-mounted CAC canisters when
regeneration is required. Large systems with integrated vapor
and liquid treatment systems will need additional area based
on vendor-specific requirements.
Standard 440V, three-phase electrical service is needed.
For many SVE applications, water may be required at the site.
The quantity of water needed is vendor- and site-specific
Contaminated soils or other waste materials are hazard-
ous, and their handling requires that a site safety plan be
developed to provide for personnel protection and special
handling measures. Storage should be provided to hold the
process product streams until they have been tested to deter-
mine their acceptability for disposal or release. Depending
upon the site, a method to store soil tailings from drilling
operations may be necessary. Storage capacity will depend
on waste volume.
Onsite analytical equipment, including gas chromato-
graphs and organic vapor analyzers capable of determining
site-specific organic compounds for performance assessment,
make the operation more efficient and provide better infor-
mation for process control.
Performance Data
SVE, as an in situ process (no excavation is involved), may
require treatment of the soil to various cleanup levels man-
dated by federal and state site-specific criteria. The time
required to meet a target cleanup level (or performance ob-
jective) may be estimated by using data obtained from bench-
scale and pilot-scale tests in a time-predicting mathematical
model. Mathematical models can estimate cleanup time to
reach a target level, residual contaminant levels after a given
period of operation and can predict location of hot spots
through diagrams of contaminant distribution [16].
Table 2 shows the performance of typical SVE applica-
tions. It lists the site location and size, the contaminants and
quantity of contaminants removed, the duration of operation,
and the maximum soil contaminant concentrations before
treatment and after treatment The data presented for specific
contaminant removal effectiveness were obtained, for the
most part, from publications developed by the respective SVE
system vendors. The quality of this information has not been
determined.
Midwest Water Resources, Inc. (MWRI) installed its
VAPORTECH™ pumping unit at the Dayton, Ohio site of a
spill of uncombusted paint solvents caused by a fire in a paint
warehouse [19]. The major VOC compounds identified were
acetone, methyl isobutyl ketone (MIBK), methyl ethyl ketone
(MEK), benzene, ethylbenzene, toluene, naphtha, xylene, and
other volatile aliphatic and alkyl benzene compounds. The
site is underlain predominantly by valley-fill glacial outwash
within the Great Miami River Valley, reaching a thickness of
over 200 feet The outwash is composed chiefly of coarse,
dean sand and gravel, with numerous cobbles and small
boulders. There are two outwash units at the site separated
by a discontinuous till at depths of 65 to 75 feet. The upper
outwash forms an unconfined aquifer with saturation at a
depth of 45 to 50 feet below grade. The till below serves as
an aquitard between the upper unconfined aquifer and the
lower confined to semiconfined aquifer. Vacuum withdrawal
extended to the depth of groundwater at about 40 to 45 feet
During the first 73 days of operation, the system yielded
3,720 pounds of volatile* and after 56 weeks of operation,
had recovered over 8,000 pounds of VOCs from the site.
Closure levels for the site were developed for groundwater
VOC levels of ketones only. These soil action levels (acetone,
810 ng/l; MIBK, 260 u.g/1, and MEK, 450 ng/l) were set so that
waters recharging through contaminated soils would result in
Table 2.
Summary of Performance Data for In Situ Soil Vapor Extraction
Site
Industrial - CA [1 7]
Sheet Metal Plant - Ml [18]
Prison Const Site - Ml [19]
Sherwin-Williams Site -OH [19]
Upjohn- PR [20][21]
UST BelK/iew - FL [7]
Verona Wellfield - Ml [7][22]
Petroleum Terminal -
Owensboro, KY [19]
SITE Program - Croveland MA [7]
Size
-
5,000 cu yds
1 65,000 cu yds
425,000 cu yds
7,000,000 cu yds
-
35,000 cu yds
1 2,000 cu yds
6,000 cu yds
Contaminants
TCE
PCE*
TCA
Paint solvents
CCI4
BTEX
TCE, PCE, TCA
Gasoline, diesel
TCE
Quantity
removed
30kg
59kg
-
4,100kg
107,000kg
9,700 kg
12,700kg
—
590kg
Duration of
operation
440 days
35 days
90 days
6 mo
3yr
7 mo
Over 1 yr
6 mo
56 days
So/7 concentration* (mg/kg)
max. before after
treatment treatment
0.53
5600
3.7
38
2200
97
1380
>5000
96.1
0.06
0.70
0.01
0.04
<0.005
<0.006
Ongoing
1.0 (target)
4.19
•PCE « Perch toroethytene
Engineering Bulletin: In Situ Soil Vapor Extraction Treatment
-------
groundwater VOC concentrations at or below regulatory
standards. The site met all the closure criteria by June 1988.
A limited amount of performance data is available from
Superfund sites. The EPA Superfund Innovative Technology
Evaluation (SITE) Program's Croveland, Massachusetts, dem-
onstration of the Terra Vac Corporation SVE process produced
data that were subjected to quality assurance/quality control
tests. These data appear in Table 2 [7, p. 29] and Table 3 [7,
p. 31 ]. The site is contaminated by trichloroethylene (TCE), a
degreasing compound which was used by a machine shop
that is still in operation. The subsurface profile in the test area
consists of medium sand and gravel just below the surface,
underlain by finer and silty sands, a clay layer 3 to 7 feet in
depth, and—below the clay layer—coarser sands with gravel.
The clay layer or lens acts as a barrier against gross infiltration
of VOCs into subsequent subsoil strata. Most of the subsur-
face contamination lay above the clay lens, with the highest
concentrations adjacent to it. The SITE data represent the
highest percentage of contaminant reduction from one of the
four extraction wells installed for this demonstration test The
TCE concentration levels are weighted average soil concen-
trations obtained by averaging split spoon sample concentra-
tions every 2 feet over the entire 24-foot extraction well
depth. Table 3 shows the reduction of TCE in the soil strata
near the same extraction well. The Croveland Superfund Site
is in the process of being remediated using this technology
[21-
The Upjohn facility in Barceloneta, Puerto Rico, is the first
and, thus far, the only Superfund site to be remediated with
SVE. The contaminant removed from this site was a mixture
containing 65 percent carbon tetrachloride (CCIJ and 35
percent acetonitrile [20]. Nearly 18,000 gallons of CCI4 were
extracted during the remediation, including 8,000 gallons
that were extracted during a pilot operation conducted from
January 1983 to April 1984. The volume of soil treated at the
Upjohn site amounted to 7,000,000 cubic yards. The respon-
sible party originally argued that the site should be considered
clean when soil samples taken from four boreholes drilled in
the area of high pretest contamination show nondetectable
levels of CO,. EPA did not accept this criterion but instead
required a cleanup criteria of nondetectable levels of CQ4 in all
the exhaust stacks for 3 consecutive months [21]. This re-
quirement was met by the technology and the site was con-
sidered remediated by EPA.
Approximately 92,000 pounds of contaminants have been
recovered from the Tyson's Dump site (Region 3) between
November 1988 and July 1990. The site consists of two
unlined lagoons and surrounding areas formerly used to store
chemical wastes. The initial Remedial Investigation identified
no soil heterogeneities and indicated that the water table was
20 feet below the surface. The maximum concentration in
the soil (total VOCs) was approximately 4 percent. The
occurence of dense nonaqueous-phase liquids (DNAPLs) was
limited in area! extent. After over 18 months of operation, a
number of difficulties have been encountered. Heterogene-
ities in soil grain size, water content, permeability, physical
structure and compaction, and in contaminant concentrations
have been identified. Soil contaminant concentrations of up
to 20 percent and widespread distribution of DNAPLs have
been found. A tar-like substance, which has caused plugging,
has been found in most of the extraction wells. After 18
months of operation, wellhead concentrations of total VOCs
have decreased by greater than 90 percent [23, p. 28].
As of December 31,1990, approximately 45,000 pounds
of VOCs had been removed from the Thomas Solvent Raymond
Road Operable Unit at the Verona Well Field site (Region 5). A
pilot-scale system was tested in the fall of 1987 and a full-scale
operation began in March, 1988. The soil at the site consists
of poorly-graded, fine-to-medium-grained loamy soils under-
lain by approximately 100 feet of sandstone. Groundwater is
located 16 to 25 feet below the surface. Total VOC concen-
trations in the combined extraction well header have de-
creased from a high of 19,000 ug/1 in 1987 to approximately
1,500ug/1 in 1990 [22].
Table 3
Extraction Well 4: TCE Reduction In Soil Strata—EPA Site Demonstration (Grovetand, MA) [7, p. 31]
Depth (ft)
0-2
2-4
4-6
6-8
8-10
10-12
12-14
14-16
16-18
18-20
20-22
22-24
Description of strata
Med. sand w/gravd
Lt brown fine sand
Med. stiff It brown fine sand
Soft die. brown fine sand
Med. stiff brown sand
V. stff It brown med. sand
V. Stiff brown fine sand w/silt
M. stff gm-bm day w/silt
Soft wet day
Soft wet day
V. stiff bm med-coarse sand
V. stiff bm med-coarse w/gravel
Hydraulic
Conductivity (cm/s)
10*
10-4
10-1
10-'
10"
10"
10"
10«
10*
10*
10"
io-J
Soil TCE concentration (mg/kg)
Pre-treatmcnt Post~tieotinent
2.94
29.90
260.0
303.0
351.0
195.0
3.14
ND
ND
ND
ND
6.17
ND
ND
39.0
9.0
ND
ND
2.3
ND
ND
ND
ND
ND
ND - Nondetectable level
Engineering Bulletin: In Situ Soil Vapor Extraction Treatment
-------
An SVE pilot study has been completed at the Colorado
Avenue Subsite of the Hastings (Nebraska) Croundwater Con-
tamination site (Region 7). Trichloroethylene (TCE), 1,1,1-
trichloroethane (TCA), and tetrachloroethylene (PCE) occur in
two distinct unsaturated soil zones. The shallow zone, from
the surface to a depth of SO to 60 feet, consists of sandy and
clayey silt. TCE concentrations as high as 3,600 ug/1 were
reported by EPA in this soil zone. The deeper zone consists of
interbedded sands, silty sands, and gravelly sands extending
from about 50 feet to 120 feet During the first 630 hours of
the pilot study (completed October 11, 1989), removal of
approximately 1,488 pounds of VOCs from a deep zone
extraction well and approximately 127 pounds of VOCs from
a shallow zone extraction well were reported. The data
suggest that SVE is a viable remedial technology for both soil
zones [24].
As of November, 1989, the SVE system at the Fairchild
Semi-conductor Corporation's former San Jose site (Region 9)
has reportedly removed over 14,000 pounds of volatile con-
taminants. Total contaminant mass removal rates for the SVE
system fell below 10 pounds per day on October 5,1989 and
fell below 6 pounds per day in December, 1989. At that time,
a proposal to terminate operation of the SVE system was
submitted to the Regional Water Quality Control Board for
the San Francisco Bay Region [25, p.3].
Resource Conservation and Recovery Act (RCRA) LDRs
that require treatment of wastes to best demonstrated avail-
able technology (BOAT) levels prior to land disposal may
sometimes be determined to be applicable or relevant and
appropriate requirements for CERCLA response actions. SVE
can produce a treated waste that meets treatment levels set
by BDAT but may not reach these treatment levels in all cases.
The ability to meet required treatment levels is dependent
upon the specific waste constituents and the waste matrix. In
cases where SVE does not meet these levels, it still may, in
certain situations, be selected for use at the site if a treatability
variance establishing alternative treatment levels is obtained.
EPA has made the treatability variance process available in
order to ensure that LDRs do not unnecessarily restrict use of
alternative and innovative treatment technologies. Treatabil-
ity variances are justified for handling complex soil and debris
matrices. The following guides describe when and how to
seek a treatability variance for soil and debris: Superfund LDR
Guide #6A, "Obtaining a Soil and Debris Treatability Variance
for Remedial Actions" (OSWER Directive 9347.3-06FS, July
1989) [13], and Superfund LDR Guide #68, "Obtaining a Soil
and Debris Treatability Variance for Removal Actions" (OSWER
Directive 9347.3-07FS, December 1989) [14]. Another ap-
proach could be to use other treatment techniques in series
with SVE to obtain desired treatment levels.
Technology Status
During 1989, at least 17 RODs specified SVE as part of
the remedial action [5]. Since 1982, SVE has been selected as
the remedial action, either alone or in conjunction with other
treatment technologies, in more than 30 RODs for Superfund
sites [2] [3] [4] [5] [6]. Table 4 presents the location, primary
contaminants, and status for these sites [3] [4] [5]. The
technology also has been used to clean up numerous under-
ground gasoline storage tank spills.
A number of variations of the SVE system have been
investigated at Superfund sites. At the Tinkhams Garage Site
in New Hampshire (Region 1), a pilot study indicated that
SVE, when used in conjunction with ground water pumping
(dual extraction), was capable of treating soils to the 1 ppm
clean-up goal [26, 3-7] [27]. Soil dewatering studies have
been conducted to determine the feasability of lowering the
water table to permit the use of SVE at the Bendix, PA Site
(Region 3) [28]. Plans are underway to remediate a stockpile
of 700 cubic yards of excavated soil at the Sodeyco Site in Mt.
Holly, NC using SVE [29].
With the exception of the Barceloneta site, no Superfund
site has yet been cleaned up to the performance objective of
the technology. The performance objective is a site-specific
contaminant concentration, usually in soil. This objective may
be calculated with mathematical models with which EPA
evaluates delating petitions for wastes contaminated with
VOCs [30]. It also may be possible to use a TCLP test on the
treated soil with a corresponding drinking water standard
contaminant level on the leachate.
Most of the hardware components of SVE are available
off the shelf and represent no significant problems of avail-
ability. The configuration, layout, operation, and design of
the extraction and monitoring wells and process components
are site specific. Modifications may also be required as dic-
tated by actual operating conditions.
On-line availability of the full-scale systems described in
this bulletin is not documented. System components are
highly reliable and are capable of continuous operation for
the duration of the cleanup. The system can be shut down, if
necessary, so that component failure can be identified and
replacemnts made quickly for minimal downtime.
Based on available data, SVE treatment estimates are
typically JSO/ton for treatment of soil. Costs range from as
low as JlO/ton to as much as JISO/ton [7]. Capital costs for
SVE consist of extraction and monitoring well construction;
vacuum blowers (positive displacement or centrifugal); vapor
and liquid treatment systems piping, valves, and fittings (usu-
ally plastic); and instrumentation [31]. Operations and main-
tenance costs include labor, power, maintenance, and moni-
toring activities. Offgas and collected groundwater treatment
are the largest cost items in this list; the cost of a cleanup can
double if both are treated with activated carbon. Electric
power costs vary by location (i.e., local utility rates and site
conditions). They may be as low as 1 percent or as high as 2
percent of the total project cost.
Caution is recommended in using these costs out of
context, because the base year of the estimates vary. Costs
also are highly variable due to site variations as well as soil and
contaminant characteristics that impact the SVE process. As
contaminant concentrations are reduced, the cost effective-
ness of an WE system may decrease with time.
Engineering Bulletin: In Sttu Soil Vapor Extraction Treatment
-------
Table 4
Superfund Sites Specifying SVE as a Remedial Action
Site
GrovetandWeUsI &2
Kellogg-Deering Well Field
South Municipal Water
Supply Wen
' Tmkham Garage
Wells G fc H
FAA Technical Center
Upjohn Manufacturing Co.
Allied Signal Aerospace-
Bendix Flight System Div.
Henderson Road
Tyson's Dump
Stauffer Chemical
Slauffer Chemical
Sodyeco
Kysor Industrial
Long Prairie
MIDCO 1
Miami County Incinerator
Pristine
Seymour Recycling
Verona Well Field
Wausau Groundwater
Contamination
South Valley/
General Electric
Hastings Groundwater
Contamination
Sand Creek Industrial
Fairchild Semiconductor
Fairchild Semiconductor/
MTV-1
Fairchild Semiconductor/
MTV-2
Intel Corporation
Raytheon Corporation
Motorola 52nd Street
Phoenix-Goodyear Airport
Area (also UtchfieW
Airoort Area)
Location (Region)
GroveUnd, MA(1)
Norwalk, a(1)
Peterborough, NH(1)
Londonderry, NH(1)
Wobum, MA(1)
Atlantic County, NJ (2)
Barcetoneta, PR (2)
South Montrose, PA (3)
i Ififwr lufof'w'm Tnu/nchin
Upper ivienon luwnMiip,
PA (3)
Upper Merion Township,
PA (3)
Cold Creek, AL (4)
Lemoyne, AL (4)
Mt Holly, NC (4)
Cadillac, Ml (5)
Long Prairie, MN (S)
Gary, IN (5)
Troy, OH (5)
Cincinnati, OH (5)
C^_WW^»«v IfLl ff\
Seymour, IN (5)
Battle Creek, Ml (5)
Wausau, WI (5)
Albuquerque, NM (6)
Hastings, NE (7)
Commerce City, CO (8)
San |ose, CA (9)
Mountain View, CA (9)
Mountain View, CA (9)
Mountain View, CA (9)
Mountain View, CA (9)
Phoenix, AZ (9)
Goodyear, AZ (9)
Primary Contaminants
TCE
PCE, TCE, and BTX
PCE, TCE, Toluene
PCE, TCE
PCE, TCE
BTX, PAHs, Phenols
Cd4
TCE
PCE, TCE. Toluene, Benzene
PCE, TCE, Toluene, Benzene,
Trichloropropane
CCU,, pesticides
CC14 , pesticides
TCE, PAHs
PCE, TCEJoluene, Xylene
PCE, TCE, DCE, Vinyl chloride
BTX, TCE, Phenol, Dichloro-
methane, 2-Butanone,
Chlorobenzene
PCE; TCE; Toluene
Benzene; Chloroform; TCE;
1,2-DCA;1,2-DCE
TCE; Toluene; Chtorometnane;
ci$-1,2-DCE;1,1,1-DCA;
CnloroTorTn
PCE, TCA
PCE, TCE
Chlorinated solvents
CCL« .Chloroform
PCE, TCE, pesticides
PCE, TCA, DCE, DCA,
Vmyl chlorides, Phenols,
and Freon
PCE, TCA, DCE, DCA,
Vinyl chlorides. Phenols,
and Freon
PCE, TCA, DO, DCA,
Vinyl chlorides, Phenols,
and Freon
PCE, TCA, DCE, DCA,
Vinyl chlorides, Phenols,
and Freon
PCE, TCA, DCE, DCA,
Vmyl chlorides. Phenols,
and Freon
TCA, TCE, CCL4 , Ethyibenzene
TCE, DCE, MEK
Status
SITE demonstration complete [2][7]
Full-scale Remediation In design
Pre-design [3] [5] [6]
Pre-design completion expected in the fall
of 1991 [3][5J[6]
Pre-design pilot study completed [26] [27]
In design [3] [5]
In design [3] [5]
Project completed in 1 988 [20] [21 ]
Pre-design tests and dewatering [28]
study completed
Pre-design [3] [4]
In operation (since 1 1 /88) [23]
Pre-design [5] [6]
Pre-design [5] [6]
Design approved [29]
In design; pilot studies in progress [3] [S] [6]
CVF rf^iOnytk^n *Yn0rt«tf4 in tH* Call A! 1 OO1
jvfc ^ujiMJu^uui i cjujvv&cu it) uic rail vi 1 rv 1
PH«]
In Design [3] [5] [6]
Pre-design [3] [5] [6]
Pre-design [3] [6]
Pre-design investigation completed [32]
Operational since 3/81 [22]
Pre-design [3] [5] [6]
Pilot studies scheduled for [4] [6]
Summer of 1 991
Pilot studies completed for [24]
Colorado Ave. & Far-Marco
subsites
Pilot study completed [33]
Operational since 1988, [25]
Currently conducting
resaturation studies
Pre-design [3] [5]
Pre-design [3] [S]
Pre-design [3] [5]
Pre-design [3] [5]
Pre-design [3] [4] [6]
North Unit - In design [34]
South Unit - pilot study completed
Engineering Bulletin: In Situ Soil Vapor Extraction Treatment
-------
EPA Contact
Technology-specific questions regarding SVE may be di-
rected to:
Michael Cruenfeld
U.S. Environmental Protection Agency
Releases Control Branch
Risk Reduction Engineering Laboratory
2890 Woodbridge Ave.
Building 10 (MS-104)
Edison, N| 08837
(FTS) 340-6924 or (908) 321-6924
Acknowledgements
This bulletin was prepared for the U.S. Environmental
Protection Agency, Office of Research and Development (ORD),
Risk Reduction Engineering Laboratory (RREL), Cincinnati, Ohio,
by Science Applications International Corporation (SAIC), and
Foster Wheeler Enviresponse Inc. (FWEI) under contract No.
68-C8-0062. Mr. Eugene Harris served as the EPA Technical
Project Monitor. Gary Baker was SAIC's Work Assignment
Manager. This bulletin was authored by Mr. Pete Michaels of
FWEI. The author is especially grateful to Mr. Bob Hillger and
Mr. Chi-Yuan Fan of EPA, RREL, who have contributed signifi-
cantly by serving as technical consultants during the devel-
opment of this document.
The following other Agency and contractor personnel
have contributed their time and comments by participating in
the expert review meetings and/or peer reviewing the docu-
ment:
Dr. David Wilson
Dr. Neil Hutzler
Mr. Seymour Rosenthal
Mr. Jim Rawe
Mr. Clyde Dial
Mr. |oe Tillman
Vanderbilt University
Michigan Technological University
FWEI
SAIC
SAIC
SAIC
a
Engineering Bulletin: In Situ Soil Vapor Extraction Treatment
-------
REFERENCES
1. Cheremesinoff, Paul N. Solvent Vapor Recovery and
VOC Emission Control. Pollution Engineering, 1986.
2. Records of Decision System Database, Office of Emer-
gency and Remedial Response, U.S. Environmental
Protection Agency, 1989.
3. Innovative Treatment Technologies: Semi-Annual Status
Report. EPA/540/2-91 /001, January 1991.
4. ROD Annual Report, FY 1988. EPA/540/8-89/006, )uly
1989.
5. ROD Annual Report, FY 1989. EPA/540/8-90/006,
April! 990.
6. Personal Communications with Regional Project
Managers, April, 1991.
7. Applications Analysis Report — Terra Vac In Situ
Vacuum Extraction System. EPA/540/A5-89/003, U.S.
Environmental Protection Agency, 1989. (SITE Report).
8. CH2M Hill, Inc. Remedial Planning/Field Investigation
Team. Verona Well Field-Thomas Solvent Co. Operable
Unit Feasibility Study. U.S. Environmental Protection
Agency, Chicago, Illinois, 1985.
9. Payne, F.C., et al. In Situ Removal of Purgeable Organic
Compounds from Vadose Zone Soils. Presented at
Purdue Industrial Waste Conference, May 14,1986.
10. Hutzler, Neil)., Blaine E. Murphy, and John S. Cierke.
State of Technology Review — Soil Vapor Extraction
Systems. U.S. Environmental Protection Agency,
Cincinnati, Ohio, 1988.
11. Johnson, P.C., et al. A Practical Approach to the Design,
Operation, and Monitoring of In Situ Soil Venting
Systems. Croundwater Monitoring Review, Spring,
1990.
12. Technology Screening Guide for Treatment of CERCLA
Soils and Sludges. EPA/540/2-88/004, U.S. Environmen-
tal Protection Agency, 1988. pp. 86-89.
13. Superfund LDR Guide #6A: Obtaining a Soil and Debris
Treatability Variance for Remedial Actions. OSWER
Directive 9347.3-06FS, U.S. Environmental Protection
Agency, 1989.
14. Superfund LDR Guide #6B: Obtaining a Soil and Debris
Treatability Variance for Removal Actions. OSWER
Directive 9347.3-07FS, U.S. Environmental Protection
Agency, 1989.
15. Michaels, Peter A., and Mary K. Stinson. Terra Vac In
Situ Vacuum Extraction Process SITE Demonstration. In:
Proceedings of the Fourteenth Annual Research Sympo-
sium. EPA/600/9-88/021, U.S. Environmental Protec-
tion Agency, 1988.
16. Mutch, Robert D., Jr., Ann N. Clarke, and David J.
Wilson. In Situ Vapor Stripping Research Project: A
Progress Report — Soil Vapor Extraction Workshop.
USEPA Risk Reduction Engineering Laboratory, Releases
Control Branch, Edison, New Jersey, 1989.
17. Ellgas, Robert A., and N. Dean Marachi. Vacuum
Extraction of Trichloroethylene and Fate Assessment in
Soils and Groundwater: Case Study in California, joint
Proceedings of Canadian Society of Civil Engineers -
ASCE National Conferences on Environmental Engineer-
ing, 1988.
18. Groundwater Technology Inc., Correspondence from
Dr. Richard Brown.
19. Midwest Water Resource, Inc.; Correspondence from
Dr. Frederick C. Payne.
20. Geotec Remedial Investigation Report and Feasibility
Study for Upjohn Manufacturing Co. Barceloneta,
Puerto Rico, 1984.
21. Geotec Evaluation of Closure Criteria for Vacuum
Extraction at Tank Farm. Upjohn Manufacturing
Company, Barceloneta, Puerto Rico, 1984.
22. CH2M Hill, Inc. Performance Evaluation Report Thomas
Solvent Raymond Road Operable Unit. Verona Well
Field Site, Battle Creek, Ml, April 1991.
23. Terra Vac Corporation. An Evaluation of the Tyson's Site
On-Site Vacuum Extraction Remedy Montgomery
County, Pennsylvania, August 1990.
24. IT Corporation. Final Report-Soil Vapor Extraction Pilot
Study, Colorado Avenue Subsite, Hastings Ground-
Water Contamination Site, Hastings, Nebraska, August,
1990.
25. Canonic Environmental. Supplement to Proposal to
Terminate In-Situ Soil Aeration System Operation at
Fairchild Semiconductor Corporation's Former San Jose
Site, December 1989.
26. Malcom Pirnie, Tinkhams Garage Site, Pre-Design Study,
Londonderry, New Hampshire - Final Report, July 1988.
27. Terra Vac Corp., Tinkhams Garage Site Vacuum Extrac-
tion Pilot Test, Londonderry, New Hampshire, July 20,
1988.
28. Environmental Resources Management, Inc. Dewater-
ing Study For The TCE Tank Area - Allied Signal Aero-
space, South Montrose, PA, December 1990.
29. Letter Correspondence from Sandoz Chemicals Corpo-
ration to the State of North Carolina Department of
Environmental Health, and Natural Resources, RE:
Remediation Activities in CERCLA C Area (Sodeyco)
Superfund Site, March 28, 1991.
30. Federal Register, Volume 50, No. 229, Wednesday,
November 27, 1985, pp. 48886-48910.
31. Assessing UST Corrective Action Technologies: Site
Assessment and Selection of Unsaturated Zone Treat-
ment Technologies. EPA/600/2-90/011, U.S. Environ-
mental Protection Agency, 1990.
32. Hydro Geo Chem, Inc. Completion Report, Pre-Design
Investigation for a Vapor Extraction at the Seymour Site,
Seymour, Indiana, February 1990.
Engineering Bulletin: In Situ Soil Vapor Extraction Treatment
-------
33. Croundwater Technology, Inc. Report of Findings - 34. Hydro Ceo Chem, Inc. Results and Interpretation of the
Vacuum Extraction Pilot Treatability at the Sand Creek Phoenix Goodyear Airport SVE Pilot Study, Goodyear,
Superfund Site (OU-1), Commerce City, Colorado, Arizona, May 1989.
March 1990.
70 Engineering Bulletin: In Situ Soil Vapor Extraction Treatment
£U.S. GOVERNMENT PRINTING OFFICE: I9»! - 64IMWOAMIHM
-------
United States Center for Environmental Research BULK RATE
Environmental Protection Information POSTAGE & FEES PAID
Agency Cincinnati, OH 45268 EPA
PERMIT No. C-35
Official Business
Penalty for Private Use $300
EPA/540/2-91/006
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&EPA
"-ti ^V3K^^f:^f '"v "• '•'^••'••^'^st'^v^^-.- .-< -r-.«v«w^""
United States
Environmental Protection
Agency
Office of Emergency and
Remedial Response
Washington, DC 20460
Office of ' *' '•"<•-•.•> •'• •" *••'
Research and Development
Cincinnati, OH 45268
Superfund
EPA/540/2-91/005
May 1991
Engineering Bulletin
In Situ Steam Extraction
Treatment
Purpose
Section 121 (b) of the Comprehensive Environmental Re-
sponse, Compensation, and Liability Act (CERCbA) mandates
the Environmental Protection Agency (EPA) to select remedies
that "utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the maxi-
mum extent practicable" and to prefer remedial actions in
which treatment "permanently and significantly reduces the
volume, toxicity, or mobility of hazardous substances, pollut-
ants and contaminants as a principal element" The Engi-
neering Bulletins are a series of documents that summarize
the latest information available on selected treatment and site
remediation technologies and related issues. They provide
summaries of and references for the latest information to help
remedial project managers, on-scene coordinators, contrac-
tors, and other site cleanup managers understand the type of
data and site characteristics needed to evaluate a technology
for potential applicability to their Superfund or other hazard-
ous waste site. Those documents that describe individual
treatment technologies focus on remedial investigation scoping
needs. Addenda will be issued periodically to update the
original bulletins.
Abstract
In situ steam extraction removes volatile and semivolatile
hazardous contaminants from soil and groundwater without
excavation of the hazardous waste. Waste constituents are
removed in situ by the technology and are not actually treated.
The use of steam enhances the stripping of volatile contami-
nants from soil and can be used to displace contaminated
groundwater under some conditions. The resultant con-
densed liquid contaminants can be recycled or treated prior
to disposal. The steam extraction process is applicable to
organic wastes but has not been used for removing insoluble
inorganics and metals. Steam is injected into the ground to
raise the soil temperature and drive off volatile contaminants.
Alternatively, steam can be injected to form a displacement
front by steam condensation to displace groundwater. The
contaminated liquid and steam condensate are then collected
for further treatment.
In situ steam extraction is a developing technology that
has had limited use in the United States. In situ steam
extraction is currently being considered as a component of
the remedy for only one Superfund site, the San Fernando
Valley (Area 1), California site [1]* [2]. However, a limited
number of commercial-scale in situ steam extraction systems
are in operation. Two types of systems are discussed in this
document the mobile system and the stationary system.
The mobile system consists of a unit that volatilizes contami-
nants in small areas in a sequential manner by injecting steam
and hot air through rotating cutter blades that pass through
the contaminated medium. The stationary system uses steam
injection as a means to volatilize and displace contaminants
from the undisturbed subsurface. Each system has specific
applications; however, the lowest cost alternative will be de-
termined by site-specific considerations. This bulletin provides
information on the technology applicability, limitations, a
description of the technology, types of residuals produced,
site requirements, the latest performance data, the status of
the technology, and sources for further information.
Technology Applicability
In situ steam extraction has been shown to be effective in
treating soil and groundwater containing such contaminants
as volatile organic compounds (VOCs) including halogenated
solvents and petroleum wastes. The technology has been
shown to be effective for extracting soluble inorganics (i.e.,
acids, bases, salts, heavy metals) on a laboratory scale [3].
The presence of semivolatile organic compounds (SVOCs)
does not interfere with extraction of the VOCs [4, p. 12]. This
process has been shown to be applicable for the removal of
VOCs including chlorinated organic solvents [4, p. 9] [5, p. i],
gasoline [6, p. 1265], and diesel [7, p. 506]. It has been
shown to be particularly effective on alkanes and alkane-
based alcohols such as octanol and butanol [8].
Steam extraction applies to less volatile compounds than
ambient vacuum extraction systems. By increasing the tem-
perature from initial conditions to the steam temperature, the
vapor pressures of most contaminants will increase, causing
them to become more volatile. Semivolatile components can
volatilize at significant rates only if the temperature is increased
[3, p. 3]. Steam extraction also may be used to remove low
boiling point VOCs more efficiently.
* [reference number, page number]
Printed on Recycled Paper
-------
Table 1
RCRA Codes for Wastes Applicable to Treatment
by In Situ Steam Extraction
Spent Halogenated Solvents used in Degreasing F001
Spent Halogenated Solvents F002
Spent Non-Halogenated Solvents F003
Spent Non-Halogenated Solvents F004
Spent Non-Halogenated Solvents FOOS
Table 2
Effectiveness of In Situ Steam Extraction
on General Contaminant Groups for
Soil and Groundwater
Contaminant Croups
a
1
.a
0
—
5!
|
Halogenated volatiles
Halogenated semivolatiles
Nonhalogenated volatiles
Nonhalogenated semivolatiles
PCBs
Pesticides
Dioxins/Furans
Organic cyanides
Organic corrosives
Volatile metals
Nonvolatile metals
Asbestos
Radioactive materials
Inorganic corrosives
Inorganic cyanides
Oxidizers
Reducers
effectiveness
Mobile
System
Soil
•
T
•
V
Q
Q
Q
Q
Q
Q
Q
Q
Q
Q
a
a
a
Groundwater
T
V
T
T
Q
Q
a
a
a
Q
a
a
a
a
Q
Q
Q
Stationary
System
Soil/
Groundwater
•
V
•
V
V
V
V
T
T
T
T
a
T
T
T
T
T
• Demonstrated Effectiveness: Successful treatability test at some scale
completed
T Potential Effectiveness: Expert opinion that technology will work
Q No Expected Effectiveness: Expat opinion that technology will not
work
Table 1 lists specific Resource Conservation and Recovery
Act (RCRA) wastes that are applicable to treatment by this
technology. The effectiveness of the two steam extraction
systems (mobile and stationary) on general contaminant
groups for soil and groundwater is shown in Table 2. Ex-
amples of constituents within contaminant groups are provided
in Reference 9, " Technology Screening Guide for Treatment
of CERCLA Soils and Sludges." Table 2 is based on the current
available information or professional judgment where no in-
formation was available. The proven effectiveness of the
technology for a particular site or waste does not ensure that
it will be effective at all sites or that the treatment efficiencies
achieved will be acceptable at all sites. For the ratings used
for this table, demonstrated effectiveness means that, based
on treatability studies at some scale, the technology was
effective for that particular contaminant and matrix. The
ratings of potential effectiveness or no expected effective-
ness are based upon expert judgment. Where potential
effectiveness is indicated, the technology is believed capable
of successfully treating the contaminant group in a particular
matrix. When the technology is not applicable or will prob-
ably not work for a particular combination of contaminant
group and matrix, a no-expected-effectiveness rating is given.
The table shows that the stationary system shows potential
effectiveness for inorganic and reactive contaminants. This is
only true if the compounds are soluble.
Limitations
Soil with high silt and clay content may become mal-
leable and unstable when wet, potentially causing problems
with support and mobility of the mobile steam extraction
system. Remediation of low permeability soil (high clay
content) requires longer treatment times [4, p. 8]. The soil
must be penetrable by the augers and free of underground
piping, wiring, tanks, and drums. Materials of this type must
be relocated before treatment can commence. Surface and
subsurface obstacles greater than 12 inches in diameter (e.g.,
rocks, concrete, wooden piles, trash, and metal) must be
removed to avoid damage to the equipment. Substantial
amounts of subsurface obstacles may preclude the use of a
mobile system. A climate temperature range of 20-100°F is
desirable for best operation of the mobile system [4, p. 18].
Mobile steam extraction systems can treat large con-
taminated areas but are limited by the depth of treatment
One system that has been evaluated can treat to a depth of
30 feet.
To be effective, the stationary steam extraction system
requires a site with predominately medium- to high-perme-
ability soil. Sites with homogeneous physical soil conditions
are more amenable to the system. If impermeable lenses of
contaminated soil exist, the stationary system may not reme-
diate these areas to desired cleanup levels [5, p. 19]. How-
ever, a combination of steam injection followed by vacuum
extraction (drying) may be effective on sites with heteroge-
neous soil conditions [10]. Steam extraction may be effective
for remediation of contaminated groundwater near the source
of contamination [5, p. 14 ] [10].
There may be residual soil contamination after applica-
tion of in situ steam extraction. Study of a mobile system
showed the average removal efficiency for volatile contami-
nants was 85%; 15% of the volatile compound contamina-
tion remained in the soil [4, p. 4]. If other organic or
inorganic contamination exists, the cleaned soil may need
subsequent treatment by some other technique (i.e., stabili-
zation).
In situ steam extraction may not remove SVOCs and in-
organics effectively. The operational costs of steam extrac-
tion are greater than ambient vacuum extraction, but may
be offset by higher recovery and/or reduction in time re-
quired to remediate the site due to more efficient removal of
contaminants.
Engineering Bulletin: In Situ Steam Extraction Treatment
-------
Figure 1
Schematic of the Mobile Steam Extraction System
Kelly Bars
Shroud
Mixing •
Blades
A
\
.
rf
\1
'™^
i
\
f
--*.
\ "V
• ^v
jm? Jk
^i
r
Steam
Generator
Water to
Cooling Tower
Blower
f~\ Y\
i
s Train
r
Condensed
, Organics
Collection
*• , Tank
/
Recycle Air
Compressors
Activated
Carbon
i
Return
Air
1 1
Sper
Cartx
V X/' v
\, Cutter Bits \
Cutter Blades
In situ steam extraction requires boilers to generate steam
and a sophisticated process to capture and treat extracted
steam and contaminants. Because the mobile system is me-
chanically complex its equipment may fail and shut down
frequently; however, mechanical problems may be corrected
fairly quickly. Equipment failure and shutdown are less fre-
quent for the stationary system.
The increase in soil temperature may adversely affect
other soil properties such as microbial populations, although
some microbial populations can withstand soil temperatures
upto140°F.
Technology Description
Figure 1 is a general schematic of a mobile steam extrac-
tion system [4, p. 48]. A process tower supports and controls
a pair of cutter blades which bore vertically through the soil.
The cutter blades are rotated synchronously in opposite direc-
tions during the treatment process to break up the soil and
ensure through-flow of gases. Steam (at 400°F) and
compressed air (at 275°F) are piped to nozzles located on the
cutter blades. Heat from the injected steam and hot air
volatilizes the organics. A steel shroud covers the area of soil
undergoing treatment. Suction produced by the blower
keeps the area underneath the shroud at a vacuum to pull
gases from the soil and to protect against leakage to the
outside environment. The offgases are pulled by the blower
from the shroud to the treatment train, where water and
organics are removed by condensation in coolers. The air-
stream is then treated by carbon adsorption, compressed,
and returned to the soil being treated. Water is removed
from the liquid stream with a gravity separator followed by
batch distillation and carbon adsorption and is then recycled
to a cooling tower. The condensed organics are collected
and held for removal and transportation.
Mobile systems treat small areas of contamination until
an entire site is remediated. The action of the cutter blades
enables the process to treat low-permeability zones (high clay
content) by breaking up the soil. Current systems treat blocks
of soil measuring 7'4" x 4' by up to 30' deep.
Figure 2 is a schematic of a stationary steam extraction
system [5, p. 9]. High-quality steam is delivered through in-
dividual valves and flow meters to the injection wells from the
manifold. Cases and liquids are removed from the soil through
the recovery wells. Gases flow through a condenser and into
a separation tank where water and condensed gases are
separated from the contaminant phase. Liquid organics are
pumped, from the separation tank through a meter and into a
holding tank. The water may require treatment by carbon
adsorption or another process to remove remaining contami-
nants. Noncondensible gases are passed through activated
carbon tanks where contaminants are adsorbed before the
cleaned air is vented to the atmosphere. A vacuum pump
maintains the subatmospheric pressure on the recovery well
and drives the flow of recovered gases. Contaminated liquids
are pumped out of the recovery well to a wastewater tank.
Engineering Bulletin: In Situ Steam Extraction Treatment
-------
Figure 2
Process Schematic of the Stationary Steam Extraction System
St6e
Gene
^•IM
Jlean Ga
\tmosph
1 1
im I
rator 1
sto
are
Valved 1
Manifold |
Carbon h uas
Adsorption |
1
Spent
Carbon
Injection 1
Wells |
\ '
Extraction 1
Well(s) |
Gas 1
Condenser 1
i •
Separator 1
Liquid
I \
Water Recovered
Liquid
Contaminants
Process Residuals
At the conclusion of both processes, the contaminants
are recovered as condensed organics in the produced water
and on the spent carbon. Residual contamination will also
remain in the soil. The recovered contaminants are tempo-
rarily stored on site and may require analysis to determine the
need for further treatment before recycling, reuse, or disposal.
Separated, cleaned water is used as cooling tower
makeup water in the mobile system. Also in this system,
cleaned gas is heated and returned as hot air to the soil.
Separated water from the stationary system must be treated
to remove residual contaminants before disposal or reuse.
The cleaned gas from this system is vented to the atmosphere.
Both systems produce contaminated granular activated carbon
from the gas cleaning. The carbon must be regenerated or
disposed. There may be minor fugitive emissions of VOCs
from the soil during treatment by the steam stripping systems
and from the gas-phase carbon beds [4, p. 2].
Site Requirements
Power and telephone lines or other overhead obstacles
must be removed or rerouted to avoid conflict with the 30-
foot treatment tower on the mobile steam extraction system.
Access roads must be available for transporting the mobile
system. Sufficient land area must be available around the
identified treatment zone to maneuver the unit and to place
support equipment and trailers. The area to be treated by the
mobile steam extraction system must be capable of support-
ing the treatment rig so that it does not sink or tip. The
ground must be flat and gradable to less than 1 % slope. A
minimum treatment area of approximately 0.5 acre (20,000
ft2) is necessary for economical use of the mobile system.
Rectangular shaped treatment areas are most efficient. The
mobile system requires a water supply of at least 8 to 10 gpm
at 30 psig. Power for the process can be provided by on-
board diesel generators [4, p. 18].
Boilers that generate steam for the stationary steam ex-
traction system use no. 2 fuel oil or other hydrocarbon fuels.
Water and electricity must be available at the site. The site
must have sufficient room for a drilling rig to install the
injection and extraction wells and for steam generation and
waste treatment equipment to be set up, as well as room for
support equipment and trailers.
Contaminated soils or waste materials are hazardous and
their handling requires that a site safety plan be developed to
provide for personnel protection and special handling mea-
sures. Storage should be provided to hold the process prod-
uct streams until they have been tested to determine their
acceptability for disposal, reuse, or release. Depending on the
site, a method to store waste that has been prepared for
treatment may be necessary. Storage capacity will depend on
waste volume.
Onsite analytical equipment capable of determining site-
specific organic compounds for performance assessment make
the operation more efficient and provide better information
for process control.
Performance Data
Toxic Treatments (USA) Inc. used a prototype of its mo-
bile system to remediate a site in Los Angeles, California. The
site soil had been contaminated by diesel and gasoline fuel
Engineering Bulletin: In Situ Steam Extraction Treatment
-------
Tabled
Total Petroleum Hydrocarbons Removed by
Toxic Treatments (USA) Inc. at Los Angeles, CA*
Table 4
Demonstration Test Results for Votatites
Removed by Toxic Treatments (USA) Inc. [4]
Calculated Value
Mean
Initial
(mg/kg)
2222
Final
(mg/kg)
191
Percent Removal
91
• This information is from vendor-published literature [7]; therefore,
quality assurance has not been evaluated.
from underground storage tanks. For this application, the
steam stripping was augmented with potassium permanganate
to promote oxidation of hydrocarbons in the highly contami-
nated zones [7, p. 506]. Table 3 summarizes the results of the
treatment by steam stripping. The level of petroleum hydro-
carbons was reduced overall by an average of 91%. The
mobile system was reported to have effectively reduced the
level of petroleum hydrocarbon compounds found in the soil
at a wide range of concentrations. However, the system's
ability to remove the higher molecular weight, less volatile
components of the diesel fuel was limited.
Under the Superfund Innovative Technology Evaluation
(SITE) program. Toxic Treatments demonstrated an average
VOC removal rate of 85 percent for a test area of 12 soil
blocks [4, p. 10] as shown in Table 4. The average VOC post-
treatment concentration was 71 ppm; the cleanup level for
the site was 100 ppm. The primary VOCs were trichloroethene,
tetrachloroethene, and chlorobenzene. The test achieved a
treatment rate of 3 cu. yds./hr. in soils having high clay con-
tent and containing some high-boiling-point VOCs. Toxic
Treatments obtained similar results in tests conducted
throughout the site; baseline testing demonstrated an aver-
age post-treatment concentration of 61 ppm. The mobile
technology also demonstrated the ability to diminish the level
of SVOCs by approximately 50%, as shown in Table 5, although
the fate of these SVOCs could not be determined [4, p. 45].
These tests were conducted on contamination in the unsatur-
ated zone. A follow-up test was conducted on six soil blocks
where treatment extended into the saturated zone. Pre-
treatment data from the vendor indicated significant VOC
contamination in this area. Post-treatment results showed
that the average level of VOC contamination in the unsaturated
zone was reduced to 53 ppm. Ketones (specifically acetone,
2-methyl-4-pentanone, and 2-butanone) were found to be
the primary contaminants in the post-treatment soil. Data
from the vendor indicated that similar reduction of VOCs
occurred in the saturated zone.
The stationary steam extraction system using steam in-
jection alone decreased soil contaminant concentrations by
90 percent in a recent pilot study [5]. High concentrations of
individual contaminants were found in a low permeability
zone by use of temperature logs. The residual high contami-
nant concentrations are thought to have been caused by: 1)
retention of highly contaminated steam condensate found
ahead of the condensation front in the dry, low-permeability
zones and 2) the decreased evaporation rate of the high-
boiling-point compounds due to the high water content in
the low permeability zones [5, p. 19]. This issue is currently
under study at the University of California, Berkeley [10].
Experimental testing has shown that a combination of steam
12-Block Test Area
Block
Number
A-25-e
A-26-e
A-27-e
A-28-e
A-29-e
A-30-e
A-31-e
A-32-e
A-33-e
A-34-*
A-35-€
A-36-e
Pre-
Treatment
(W/9)
54
28
642
444
850
421
788*
479
1133
431
283
153
Post-
Treatment
(W/9)
14
12
29
34
82
145
61
64
104
196
60
56
Percent
Removal
73
56
96
92
90
65
92
87
91
54
79
64
' Only analyses from two of the three sample cores taken were available.
Table 5
Demonstration Test Results for Semrvolatiles
Removed by Toxic Treatments (USA) Inc. [4]
12-Block Test Area
Block
Number
A-25-e
A-26-e
A-27-e
A-28-e
A-29-e
A-30-e
A-31-e
A-32-e
A-33-e
A-34-e
A-35-e
A-36-e
Pre-
Treatment
fcg/g)
595
1117
1403
1040
1310
1073
781
994
896
698
577
336
Post-
Treatment
(vy/g)
82
172
439
576
726
818
610
49
763
163
192
314
Percent
Removal
86
85
69
45
45
24
22
95
15
77
67
7
Engineering Bulletin: In Situ Steam Extraction Treatment
-------
injection and vacuum extraction can effectively remove vola-
tile contaminants from a heterogeneous soil type [10]. Steam
injection followed by vacuum extraction produces an effec-
tive drying mechanism. The process achieves greater con-
taminant removals by enhancing the vapor flow from low- to
high-permeability regions.
Performance data may be forthcoming from full-scale
stationary system steam extraction projects being conducted
by Solvent Service, Inc. and Hydro-Fluent, Inc. Data from
laboratory-scale studies are also available [6] [3].
RCRA Land Disposal Restrictions (LDRs) that require treat-
ment of wastes to best demonstrated available technology
(BOAT) levels prior to land disposal may sometimes be deter-
mined to be applicable or relevant and appropriate require-
ments for CERCLA response actions. The in situ steam extrac-
tion technology produces liquid contaminants which may be
recyclable or may require treatment to meet treatment levels
set by BDAT. A common approach to treating liquid waste
may be to use other treatment techniques in series with in situ
steam extraction.
Technology Status
In situ extraction is being considered as a component of
the selected remedy for the San Fernando Valley (Area 1) site
in Burbank, California. The Area 1 site consists of an aquifer
contaminated with VOCs, including TCE and PCE [1, p.145].
Toxic Treatments' mobile steam extraction technology
(Detoxifier™) was used in 1986 to remediate 4,700 cu. yds.
of soil contaminated with diesel fuel at the Pacific Commerce
Center site in Los Angeles, California [7, p. 506].
In 1987, Toxic Treatments' mobile steam extraction sys-
tem was selected as the remedial action to clean up approxi-
mately 8,700 cu. yds. of soil contaminated with VOCs and
SVOCs at the GATX Annex Terminal site in San Pedro, California
[11, p. 1-1 ]. Treatability testing of the technology at the site
has been underway to validate its performance prior to full
site remediation. This system also has been evaluated under
the SITE program at the site in San Pedro, California. Toxic
Treatments expects to have a second generation Detoxrfier™
available soon, which will be capable of operating on grades
up to 5 percent.
For the mobile technology, the most significant factor
influencing cost is the time of treatment or treatment rate.
Treatment rate is influenced primarily by the soil type (soils
with higher clay content require longer treatment times), the
waste type, and the on-line efficiency. Cost estimates for this
technology are strongly dependent on the treatment rate and
range. A SITE demo indicated costs of $111-317/cu. yd. (for
10 and 3 cu. yd. treatment rates, respectively). These costs
are based on a 70% on-line efficiency [4, p. 28].
Solvent Service, Inc. is using and testing its first full-scale
stationary Steam Injection Vapor Extraction (SIVE) system at
its San Jose, California, facility for remediation to a depth of
20 feet of up to 41,000 cu. yds. of soil contaminated with
numerous organic solvents [5, p. 3] [10]. Solvent Service
hopes to make the SIVE system available for other applications
in the future. The system consists of injection and extraction
wells and a gas and liquid treatment process. Equipment for
steam generation and extraction and contaminated gas/liquid
treatment are trailer mounted.
Hydro-Fluent, Inc. is designing and constructing its first
full-scale stationary steam extraction system to be used in
Huntington Beach, California for recovery of 135,000 gallons
of diesel fuel in soil to a depth of 40 feet at the Rainbow
Disposal, Nichols Avenue site [12]. Bench and pilot-scale
studies have been conducted.
For the stationary steam extraction system, the most
significant factor influencing cost is the number of wells re-
quired per unit area, which is related to the depth of con-
tamination and soil permeability. Shallow contamination
requires lower operating pressures to prevent soil fracturing,
and wells are placed closer together. Deeper contamination
allows higher operating pressures and greater well spacing;
therefore, fewer wells and lower capital cost Cost estimates
for this technology range from about J50-300/cu. yd., de-
pending on site characteristics [10].
EPA Contact
Technology-specific questions regarding in situ steam
extraction may be directed to:
Michael Cruenfeld
U.S. Environmental Protection Agency
Releases Control Branch
Risk Reduction Engineering Laboratory
2890 Woodbridge Avenue
Building 10(MS-104)
Edison, NJ 08837
FTS 340-6625
(908)321-6625
Acknowledgments
This bulletin was prepared for the U.S. Environmental
Protection Agency, Office of Research and Development (ORD),
Risk Reduction Engineering Laboratory (RREL), Gncinnati, Ohio,
by Science Applications International Corporation (SAIQ un-
der contract No. 68-C8-0062. Mr. Eugene Harris served as
the EPA Technical Project Monitor. Mr. Gary Baker was SAIC's
Work Assignment Manager. This bulletin was authored by
Mr. Kyle Cook of SAIC. The project team included Mr. Jim
Rawe and Mr. joe Tillman of SAIC. The author is especially
grateful to Mr. Bob Hillger and Dr. John Brugger of EPA, RREL,
who have contributed significantly by serving as technical
consultants during the development of this document
The following other Agency and contractor personnel
have contributed their time and comments by participating in
the expert review meetings and/or peer reviewing the docu-
ment:
Mr. Clyde Dial
Mr. Vic Engleman
Mr. Trevor Jackson
Mr. Lyie Johnson
Dr. Kent Udell
SAIC
SAIC
SAIC
Western Research Institute
Udell Technologies
Engineering Bulletin: In Situ Steam Extraction Treatment
-------
REFERENCES
1. ROD Annual Report, FY1989. EPA/540/8-90/006, U.S.
Environmental Protection Agency, 1990.
2. Personal Communications with the Regional Project
Manager, April, 1991.
3. Udell, K.S., and LD. Stewart. Combined Steam Injection
and Vacuum Extraction for Aquifer Cleanup. Presented
at Conference of the International Association of
Hydrogeologists, Calgary, Alberta, Canada, 1990.
4. Applications Analysis Report—Toxic Treatments' In Situ
Steam/Hot-Air Stripping Technology, San Diego, CA.
Report to be published, U.S. Environmental Protection
Agency, 1990. (SITE Report).
5. Udell, Kent S., and L D. Stewart Field Study of In Situ
Steam Injection and Vacuum Extraction for Recovery of
Volatile Organic Solvents. University of California
Berkeley-SEEHRL Report No. 89-2, June 1989.
6. Udell, K. S., ]. R. Hunt, and N. Sitar. Nonaqueous Phase
Liquid Transport and Cleanup 2. Experimental Studies.
Water Resources Research, 24 (8): 1259-1269,1988.
7. La Mori, Phillip N. and M. Ridosh. In Situ Treatment
Process for Removal of Volatile Hydrocarbons from Soils:
Results of Prototype Test. EPA/600/9-87/018F, U.S.
Environmental Protection Agency, 1987.
8. Lord, A.E., Jr., R.M. Koemer, D.E. Hullings, and J.E.
Brugger. Laboratory Studies of Vacuum-Assisted Steam
Stripping of Organic Contaminants from Soil. Presented
at the 15th Annual Research Symposium: Remedial
Action, Treatment, and Disposal of Hazardous Waste.
EPA/600/9-90/006, U.S. Environmental Protection
Agency, 1990.
9. Technology Screening Guide for Treatment of CERCLA
Soils and Sludges. EPA/540/2-88/004, U.S. Environmen-
tal Protection Agency, 1988.
10. Udell, Kent S. Personal Communication. July 23, 1990.
11. Harding Lawson Associates, Remedial Design, Annex
Terminal Site, San Pedro, California. Prepared for GATX
Terminals Corporation, 1987.
12. Toxic Cleanup Going Underground. The Orange
County Register, June 25, 1990, pp. A1 and A14.
Engineering Bulletin: In Situ Steam Extraction Treatment
-------
United States Center for Environmental Research BULK RATE
Environmental Protection Information POSTAGE & FEES PAID
Agency Cincinnati, OH 45268 EPA
PERMIT No. C-35
Official Business
Penalty for Private Use $300
EPA/540/2-91/005
-------
United States
Environmental Protection
Agency
Office of
Solid Waste and
Emergency Response
EPA/542/F-92/010
March 1992
c/EPA
A Citizen's Guide To
Air Sparging
Technology Innovation Office
.Technology Fact Sheet
CONTENTS
Page
What Is Air Sparging? 1
How Does H Work? 1
Why Consider Air
Sparging? 2
Will Air Sparging Work
At Every Site? 3
Where Is Air Sparging
Being Used? 3
For More Information 3
What Is Air Sparging?
Air sparging is an innovative
treatment technology that injects
air into the saturated zone (that
part of the subsurface that is
soaked with ground water) to
remove hazardous contaminants.
The air is injected below the
contaminated area, forming
bubbles that rise and carry
trapped and dissolved contam-
inants into the unsaturated zone
(that part of the subsurface
located above the ground water).
Through a subsequent treatment
technology, soil vapor extraction,
the contaminants can be
removed and treated as
necessary. (See, at right, a brief
discussion on "What Is Soil
Vapor Extraction?") Since air
sparging effectively moves the
contaminants upward into the
unsaturated zone, this technology
is typically used in conjunction
with soil vapor extraction.
What it Soil Vapor
Extraction?
Soil vapor extraction Is an
effective treatment
technology that can be used
to tract volatile organic
compounds (VOCs) In the
unsaturated zone. This
technology uses a vacuum to
draw air through
underground wells to
vaporize the VOCs found in
the soil. When soil vapor
extraction Is used alone, it
has limited effectiveness In
treating contaminants that
exist in the saturated zone.
X • s
How Does It Work?
Figure 1, on the following page,
provides a schematic diagram of
the air sparging process. The
process begins by installing air
injection wells into the ground
water below the contaminants.
The number of wells installed at
a site is determined by the size of
Air Sparging Profile
Extends the effectiveness of soil vapor extraction to Include contaminants that exist In ground water.
• Allows hazardous wastes to be treated on site.
• Provides an oxygen source which may stimulate bioremedlatlon of some contaminants.
Produced by the
Supezfund Prognni
Printed on Recycled Paper
-------
' Figure 1
Cross-Section Of An Air Sparging/Vapor Extraction System
Air Inject
Wall
Monitoring , '
Soli Gas Well 1
Monitor V ^ f /
p^i n
o Oo
o°oo0o°o
o° oc
y
3
)
^""^ /""N
00^
t
— —
Air
Compressor
on /
/ Vacuum Pump
J VOC Gases /
r ,f
^ ^v^3i> .:? ^:>5^^^>;^^^fi»a»-^ ill
f TTTTTTTTTI
Treatment
System
j|||-^~"
rtem
/^ y Unsaturated
7 ) w 2one
V / Water f
^o^S^o°o
nXOjDO O
^5/00 0 0 Sat"rated
•^r Op, O O e
the contaminated area and by various geological
and engineering considerations.
One or more air compressors are used to force air
down the injection well and out through a
screened opening, causing bubbles to form. The
bubbles move upward and outward. The bubbles
dislodge trapped contaminants, vaporize dissolved
contaminants, and carry them up to the
unsaturated zone.
As the volatile organic compound (VOC) vapors
reach the unsaturated zone, they are pulled into
vapor extraction wells that are screened in this
zone. The air sparging treatment process is
designed and operated in conjunction with the soil
vapor extraction system to ensure VOCs are
properly removed to the surface for treatment.
The performance of air sparging is monitored in
two ways. The first measures the contaminants
that are emitted by the vapor extraction system to
ensure the VOCs are properly captured and
treated. The second method involves installing
monitoring wells and surface monitors within and
around the contaminated area to determine if
additional collection and treatment processes are
needed. These two monitoring systems are
operated simultaneously.
Air sparging provides an oxygen source which
may stimulate bioremediation of some
contaminants. Bioremediation is an innovative
treatment technology that uses microorganisms,
such as bacteria, to break down organic
contaminants into harmless substances.
Why Consider Air Sparging?
There are several advantages to using air sparging
as a treatment method. Air sparging:
• Extends the effectiveness of soil vapor
extraction to include volatile contaminants
that exist in the saturated zone
• Allows hazardous wastes to be treated on-
site
• Can potentially provide a quick and
effective means of ground water clean-up
for VOCs.
-------
Will Air Sparging Work At Every Site?
All waste types and site conditions are not similar.
Each site must be individually investigated and
tested. Engineering and scientific judgement must
be used to determine if a technology is
appropriate for a site.
Air sparging is only useful at sites that contain
soils and other characteristics that can be
effectively treated by soil vapor extraction. In
addition, for air sparging to be successful, soils in
the saturated zones must allow the injected air to
readily escape into the ground water. Coarse
grained soils such as sand and gravel particles
allow greater movement than fine grained soils,
such as silt and clay. Air sparging, therefore, will
work fastest at sites where there are coarse
grained soils. The most common contaminants
treated by this technology are VOCs such as:
trichloroethane, trichloroethylene, benzene,
toluene, ethylbenzene, and xylene.
Where Is Air Sparging Being Used?
Air sparging was first used as a remediation
technology in Germany in 1985 to enhance the
clean-up of ground water contaminated with
chlorinated solvents. Currently, air sparging is
widely practiced at hazardous waste sites
throughout Europe. In the United States air
sparging has been used on a limited basis at
Superfund sites. It has been used most often to
treat underground gasoline tank spills.
What Is An Innovative
Treatment Technology?
Tmatmenf technologies are processes
applied to the treatment of hazardous
waste or contaminated materials to
permanently alter their condition
through chemical, biological, or
physical means. Technologies that
have been tested, selected or used lor
treatment of hazardous waste or
contaminated materials but lack well-
documented cost and performance .
date under a variety of operating
conditions are called Innovativ*
treatment technologies.
For More Information
EPA prepared this fact sheet to provide basic information on air sparging. Additional technical reports and
articles are listed below. The first document can be obtained by telephone or written request to:
Center for Environmental Research Information
26 West Martin Luther King Drive
Cincinnati, OH 45268
(513)569-7562
The others may be available through your local library. There may be a charge for the EPA document.
• The Superfund Innovative Technology Evaluation Program: Technology Profiles, EPA/540/5-91/008.
Groundwater Monitoring Review. "Application of In Situ Air Sparging as an Innovative Soils and
Groundwater Remediation Technology," Spring 1992. Article by Michael C. Marley.
• The Hazardous Waste Consultant. "Air Sparging Improves Effectiveness of Soil Vapor Extraction
Systems," March/April 1991.
NOTICE: This taa sheet is intended solely as general guidance and information. It is not intended, nor can it be relied upon, to create any rights enforceable by any
party in negation with the United Stales. The Agency also reserves the right to change this guidance at any time without public notice.
•U.S. Government Printing Office: 1992— 648-OOV60010
-------
Section 8
-------
CARBON ADSORPTION
STUDENT PERFORMANCE OBJECTIVES
At the conclusion of this unit, students will be able to:
1. List three raw materials used in the activated carbon
manufacturing process
2. Describe the activated carbon manufacturing process
3. List three factors that influence the use of carbon adsorption
as a treatment
4. List three design considerations assessed prior to using
carbon adsorption in an aqueous waste treatment process
5. Describe the differences between upflow and downflow
carbon adsorption systems
6. Describe the activated carbon regeneration process
7. Describe alternative disposal options that can be used when
regeneration is not feasible.
Economics should be calculated for each project.
NOTE: Unless otherwise stated, the conditions for
performance are using all references and materials
provided in the course, and the standards of
performance are without error.
7/95
-------
NOTES
CARBON
ADSORPTION
[
ACTIVATED CARBON APPLICATIONS
•/( Contaminant removal from different media
- Gas
- Liquids
• Remediation
• Municipal and industrial applications
S-2
CARBON ADSORPTION
Po'ycyclic aromatic hydrocarbons
Aromatic ring/cyclic hydrocarbons
Chlorinated organic compounds
- Volatiles
- Extractables
S-3
7/95
Carbon Adsorption
-------
NOTES
CARBON ADSORPTION
Chemical Characteristics
Nonpolar organics
Molecular weight >50 g/mol
(4-20 carbon atoms)
8-4
CARBON ADSORPTION (cont.)
Chemical Characteristics
Aromatics better than
(double or triple bonds inhibit)
Adsorptive capacity at least 50 mg/g
S-5
CARBON ADSORPTION
Physical Phenomena
Van der Waals forces 99%
Chemisorption 0.99%
Ionic bonding 0.01%
Carbon Adsorption
7/95
-------
NOTES
ACTIVATED CARBON
Raw Materials
• Bituminous coal
• Coconut shells
• Lignite
• Pulp mill residue
• Wood
8-7
ACTIVATED CARBON
Production
Step 1 - Dehydration
- Thermal and chemical
- Structural water
Step 2 - Degradation and evolution
Step 3 - Exothermal decomposition and
by-product formation
s-s
ACTIVATED CARBON (cont.)
Production
Step 4 - Carbonization
- Limited oxygen
- Crystallization (formation of pore
structures)
Step 5 - Activation
- Thermal and steam
- Macropores
S-9
7/95
Carbon Adsorption
-------
/VOTES
ACTIVATED CARBON
Pore Sizes
• 1 Angstrom = 10* cm
/"
• 60 to 80% of the pores <40 angstrom)
• Macropores >5000 angstroms
• Mesopores 40-5000 angstroms
• Micropores <40 angstroms
Bombay & Sutcltlfe Corp. 190S
8-10
ACTIVATED CARBON
Physical Characteristics
• Bulk Density = 26-40 Ibs/ft3
• Pore volume = 0.70 to 0.90 cm3/g
(70 to 90% of particle)
• Effective sizes
- Granular activated carbon
(GAG) >0.55 mm
- Powdered activated carbon
(PAC) <0.55 mm
3-11
ACTIVATED CARBON
Surface Area
500-1400 m2/g
150 acres/lb
S-12
Carbon Adsorption
7/95
-------
NOTES
ACTIVATED CARBON
Applications
Aqueous phase
Vapor phase
ACTIVATED CARBON
Aqueous System Design
Influent pretreatment 6^ 4
Temperature
pH 6-2
Contact time
Parallel or series arrangement
ACTIVATED CARBON (cont.)
Aqueous System Design
8-13
S-14
-200*
Upflow systems (pressure)
- Expanded bed (continuous backwash)
- Pulsed bed (no backwash)
Downflow systems (pressure or gravity)
- Backwash required
- Most common mobile design
Flow rate varies with application
IS
7/95
Carbon Adsorption
-------
NOTES
ACTIVATED CARBON
Vapor Phase System Design
• Humidity <50%
• Operating temperature <250°F
• Flow rates variable i^op
• Pretreatment recommended
3-18
ACTIVATED CARBON SETUP
Pretreat (oil/water separator)
Prewet aqueous waste for acclimation and
air removal
Set flow rate below design
Monitor effluent for breakthrough-
Develop backwash schedule
S-17
ACTIVATED CARBON
Waste Generated
Backwash water
- Collect and analyze
- Determine treatment
- Recycle to system
Spent carbon
- Regenerate
- Determine disposal and handling
options
^
8-18
Carbon Adsorption
7/95
-------
NOTES
ACTIVATED CARBON
Carbon Regeneration
Desorb organics
- Thermal
- Desorbed organics usually destroyed
by combustion
Reactivate carbon
- Thermal and steam
- Reactivation restores approximately
85 to 90% capacity
3-18
ACTIVATED CARBON
Disposal Options
• Incineration
• Landfill
• Fuels blending
S-20
ACTIVATED ADSORPTION
Recent Applications
Adsorb organics from soil before
stabilization
Expanded bed bioreactors
Lagoons (wastewater)
S-21
7/95
Carbon Adsorption
-------
NOTES
ACTIVATED CARBON
Costs
Cost of carbon per pound
- $1.05 to $1.70 for virgin carbon
- $0.95 to $1.40 for regenerated carbon
Total costs per 1000 gallons treated
- $0.30 to $0.85 (influent in ppb)
- $0.60 to $3.00 (influent in ppm)
Btumboy A SutcSHt Corp. »885
8-22
Carbon Adsorption
7/95
-------
REFERENCES
Barnebey & Sutcliffe Corp. 1995. Personal communication (telephone call to Barnebey & Sutcliffe
Corp. Carbon Sales Division, Columbus, OH, from A. Schmidt, Halliburton NUS Corporation,
Cincinnati, OH, on March 27, 1995, regarding costs of activated carbon).
U.S. EPA. 1991. Engineering Bulletin: Granular Activated Carbon Treatment. EPA/540/2-
91/005. U.S. Environmental Protection Agency, Office of Research and Development, Risk
Reduction Engineering Laboratory, Cincinnati, OH.
7/95 9 Carbon Adsorption
-------
vvEPA
United States
Environmental Protection
Agency
Office of Emergency and
Remedial Response
Washington, DC 20460
Office of
Research and Development
Cincinnati. OH 45268
Superfund
EPA/540/2-91/024
October 1991
Engineering Bulletin
Granular Activated
Carbon Treatment
Purpose
Section 121(b) of the Comprehensive Environmental Re-
sponse, Compensation, and Liability Act (CERCLA) mandates
the Environmental Protection Agency (EPA) to select remedies
that "utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the maximum
extent practicable" and to prefer remedial actions in which
treatment "permanently and significantly reduces the volume,
toxicity, or mobility of hazardous substances, pollutants, and
contaminants as a principal element." The Engineering Bulletins
are a series of documents that summarize the latest information
available on selected treatment and site remediation technolo-
gies and related issues. They provide summaries of and refer-
'ences for the latest information to help remedial project man-
agers, on-scene coordinators, contractors, and other site cleanup
managers understand the type of data and site characteristics
needed to evaluate a technology for potential applicability to
their Superfund or other hazardous waste site. Those documents
that describe individual treatment technologies focus on reme-
dial investigation scoping needs. Addenda will be issued peri-
odically to update the original bulletins.
Abstract
Granular activated carbon (CAC) treatment is a physico-
chemical process that removes a wide variety of contaminants
by adsorbing them from liquid and gas streams [1, p. 6-3]. This
treatment is most commonly used to separate organic con-
taminants from water or air; however, it can be used to remove
a limited number of inorganic contaminants [2, p. 5-17]. In
most cases, the contaminants are collected in concentrated
form on the CAC, and further treatment is required.
The contaminant (adsorbate) adsorbs to the surfaces of
the microporous carbon granules until the CAC becomes ex-
hausted. The CAC may then be either reactivated, regenerated,
or discarded. The reactivation process destroys most contami-
nants. In some cases, spent CAC can be regenerated, typically
using steam to desorb and collect concentrated contaminants
tfor further treatment. If CAC is to be discarded, it may have to
"be handled as a hazardous waste.
' [reference number, page number]
Site-specific treatability studies are generally necessary to
document the applicability and potential performance of a
CAC system. This bulletin provides information on the tech-
nology applicability, technology limitations, a technology de-
scription, the types of residuals produced, site requirements,
latest performance data, status of the technology, and sources
for further information.
Technology Applicability
Adsorption by activated carbon has a long history of use as
a treatment for municipal, industrial, and hazardous waste
streams. The concepts, theory, and engineering aspects of the
technology are well developed [3]. It is a proven technology
with documented performance data. GAC is a relatively non-
specific adsorbent and is effective for removing many organic
and some inorganic contaminants from liquid and gaseous
streams [4].
The effectiveness of CAC as an adsorbent for general con-
taminant groups is shown in Table 1. Examples of constituents
within contaminant groups are provided in "Technology
Screening Guide for Treatment of CERCLA Soils and Sludges"
[5]. This table is based on current available information or
professional judgment when no information was available. The
proven effectiveness of the technology for a particular site or
waste does not ensure that it will be effective at all sites or that
the treatment efficiency achieved will be acceptable at other
sites. For the ratings used for this table, demonstrated effec-
tiveness means that, at some scale, treatability was tested to
show that, for that particular contaminant and matrix, the
technology was effective. The ratings of potential effectiveness
and no expected effectiveness are based upon expert judge-
ment. Where potential effectiveness is indicated, the technology
is believed capable of successfully treating the contaminant
group in a particular matrix. When the technology is not
applicable or will probably not work for a particular combina-
tion of contaminant group and matrix, a no-expected-effective-
ness rating is given.
The effectiveness of CAC is related to the chemical com-
position and molecular structure of the contaminant. Or-
-------
Table 1
Effectiveness of Granular Activated Carbon on
General Contaminant Groups
Table 2
Organic Compounds Amenable to
Adsorption by GAC [1 ]
Contaminant Croups
1
0
Inorganic
1
Halogenated volatiles
Halogenated semivolatiles
Nonhalogenated volatiles3
Nonhalogenated semivolatiles
PCBs
Pesticides
Dioxins/Furans
Organic cyanides '
Organic corrosives •
Volatile metals*
Nonvolatile metals *
Asbestos
Radioactive materials '
Inorganic corrosives
Inorganic cyanides b
Oxidizers6
Reducers
Liquid /Cos
T
3
Q
a
• Demonstrated Effectiveness: Successful treatability test at some scale
completed
T Potential Effectiveness: Expert opinion that technology will work.
J No Expected Effectiveness: Expert opinion that technology will not work
* Technology is effective for some contaminants in the group; it may not
be effective for others.
b Applications to these contaminants involve both adsorption and chemical
reaction.
ganic wastes that can be treated by GAC include com-
pounds with high molecular weights and boiling points and
low solubility and polarity [6]. Organic compounds treat-
able by CAC are listed in Table 2. GAC has also been used to
remove low concentrations of certain types of inorganics
and metals; however, it is not widely used for this application
[1, p. 6-13].
Almost all organic compounds can be adsorbed onto
GAC to some degree (2, p. 5-17]. The process is frequently
used when the chemical composition of the stream is not fully
analyzed [1, p. 6-3]. Because of its wide-scale use, GAC has
probably been inappropriately selected when an alternative
technology may have been more effective [7]. GAC can be
used in conjunction with other treatment technologies. For
example, GAC can be used to remove contaminants from the
offgas from air stripper and soil vapor extraction operations
[7] [8, p. 73] [9].
Class
Example
Aromatic solvents
Polynuclear aromatics
I Chlorinated aromatics
Phenolics
Aromatic amines and
high molecular weight
aliphatic amines
Surfactants
Soluble organic dyes
1 Fuels
Chlorinated solvents
Aliphatic and aromatic acids
Pesticides/herbicides
Benzene, toluene, xylene
Naphthalene, biphenyl
Chlorobenzene, PCBs, endrin,
toxaphene, DOT
Phenol, cresol, resorcinol,
nitrophenols, chlorophenols,
alkyl phenols
Aniline, toluene diamine
Alkyl benzene sulfonates
Methylene blue, textile dyes
Gasoline, kerosene, oil
Carbon tetrachloride,
perchloroethylene
Tar acids, benzole acids
2,4-D, atrazine, simazine,
aldicarb, alachlor, carbofuran
Limitations
Compounds that have low molecular weight and high
polarity are not recommended for GAC treatment Streams
with high suspended solids (> SO mg/L) and oil and grease (>
10 mg/L) may cause fouling of the carbon and require frequent
backwashing. In such cases, pretreatment prior to GAC, is
generally required. High levels of organic matter (e.g., 1,000
mg/L) may result in rapid exhaustion of the carbon. Even lower
levels of background organic matter (e.g., 10-100 mg/L) such
as fulvic and humic acids may cause interferences in the adsorp-
tion of specifically targeted organic contaminants which are
present in lower concentrations. In such cases, GAC may be
most effectively employed as a polishing step in conjunction
with other treatments.
The amount of carbon required, regeneration/reactivation
frequency, and the potential need to handle the discarded GAC
as a hazardous waste are among the important economic con-
siderations. Compounds not well adsorbed often require large
quantities of GAC, and this will increase the costs. In some
cases the spent GAC may be a hazardous waste, which can
significantly add to the cost of treatment.
Technology Description
Carbon is an excellent adsorbent because of its large surface
area, which can range from 500-2000 m2/g, and because its
diverse surfaces are highly attractive to many different types of,
contaminants [3]. To maximize the amount of surface available
Engineering Bulletin: Granular Activated Carbon Treatment
-------
Figure 1. Schematic Diagram of Fixed-Bed GAC System
(CONTAMINATED
LIQUID)
INFLUENT
CARBON BED
(3)
EFFLUENT
(TREATED WATER)
(2)
SPENT CARBON
for adsorption, an activation process which increases the sur-
face-to-volume ratio of the carbon is used to produce an exten-
sive network of internal pores. In this process, carbonaceous
materials are converted to mixtures of gas, tars, and ash. The tar
is then burned off and the gases are allowed to escape to produce
a series of internal micropores [1, p. 6-6]. Additional processing
of the GAC may be used to render it more suitable for certain
applications (e.g. impregnation for mercury or sulfur removal).
The process of adsorption takes place in three steps [3].
First the contaminant migrates to the external surface of the
CAC granules. It then diffuses into the GAC pore structure.
Finally, a physical or chemical bond forms between the con-
taminant and the internal carbon surface.
The two most common reactor configurations for GAC
adsorption systems are the fixed bed and the pulsed or moving
bed [3]. The fixed-bed configuration is the most widely used
for adsorption from liquids, particularly for low to moderate
concentrations of contaminants. GAC treatment of contami-
nated gas streams is done almost exclusively in fixed-bed reac-
tors. The following technical discussion applies to both gas and
liquid streams.
Figure 1 is a schematic diagram of a typical single-stage,
fixed-bed GAC system for use on a liquid stream. The contami-
nant stream enters the top of the column (1). As the waste
stream flows through the column, the contaminants are ad-
sorbed. The treated stream (effluent) exits out the bottom (2).
Spent carbon is reactivated, regenerated, or replaced once the
effluent no longer meets the treatment objective (3). Although
Figure 1 depicts a downward flow, the flow direction can be
upward, depending on design considerations.
Suspended solids in a liquid stream or paniculate matter in
a gaseous stream accumulate in the column, causing an in-
crease in pressure drop. When the pressure drop becomes too
high, the accumulated solids must be removed, for example by
backwashing. The solids removal process necessitates adsorber
downtime, and may result in carbon loss and disruption of the
mass transfer zone. Pretreatment for removal of solids from
streams to be treated by GAC is, therefore, an important design
consideration.
As a GAC system continues to operate, the mass-transfer
zone moves down the column. Figure 2 shows the adsorption
pattern and the corresponding effluent breakthrough curve [3].
The breakthrough curve is a plot of the ratio of effluent concen-
tration (C,) to influent concentration (CJ as a function of water
volume or air volume treated per unit time. When a predeter-
mined concentration appears in the effluent (CB), breakthrough
has occurred. At this point, the effluent quality no longer meets
treatment objectives. When the carbon becomes so saturated
with the contaminants that they can no longer be adsorbed,
the carbon is said to be spent (Ce=C0). Alternative design
arrangements may allow individual adsorbers in multi-adsorber
systems to be operated beyond the breakpoint as far as com-
plete exhaustion. This condition of operation is defined as the
operating limit (Ce=CL) of the adsorber.
The major design variables for liquid phase applications of
GAC are empty bed contact time (EBCT), CAC usage rate, and
system configuration. Particle size and hydraulic loading are
often chosen to minimize pressure drop and reduce or elimi-
nate backwashing. System configuration and EBCT have an
impact on GAC usage rate. When the bed life is longer than 6
months and the treatment objective is stringent (Ce/C0 < 0.05),
Engineering Bulletin: Granular Activated Carbon Treatment
-------
Figure 2
Breakthrough Characteristics of Fixed-Bed GAC Adsorper [3]
C(z,t)
0 CQ
Saturated
Zone
(S)
Adsorption
Zone
(A)
Co
_L
Co
Co
^r~ ^r~ i
ce=o ce 0.3), blending of
effluents from partially saturated adsorbers can be used to
reduce CAC usage rate. When stringent treatment objectives
are required (Cg/C,, < 0.05) and CAC bed life is short (less than
6 months) multiple beds in series may be used to decrease GAC
usage rate.
For gas-phase applications, the mass transfer zone is usu-
ally very short if the relative humidity is low enough to prevent
water from filling the GAC pores. The adsorption zone (Figure
2) for gas-phase applications is small relative to bed depth, and
the GAC is nearly saturated at the breakpoint. Accordingly,
EBCT and system configuration have little impact on GAC
usage rate and a single bed or single beds operated in parallel
are commonly used.
GAC can be reactivated either onsite or offsite. The choice is
usually dictated by costs which are dependent on the site and on
the proximity of offsite facilities that reactivate carbon. Generally
onsite reactivation is not economical unless more than 2,000
pounds per day of GAC are required to be reactivated. Even so,
an offsite reactivation service may be more cost effective [10].
The basic evaluation technique for initial assessment of the
feasibility of GAC treatment is the adsorption isotherm test
This test determines if a compound is amenable to GAC adsorp-
tion and can be used to estimate minimum GAC usage rates.
More detailed testing such as small-scale column tests and pilot
tests should be conducted if the isotherms indicate GAC can
produce an effluent of acceptable quality at a reasonable carbon
usage rate [10].
Process Residuals
The main process residual produced from a GAC system is
the spent carbon containing the hazardous contaminants. When
the carbon is regenerated, the desorbed contaminants must be
treated or reclaimed. Reactivation of carbon is typically accom-
plished by thermal processes. Elevated temperatures are em-
ployed in the furnace and afterburners to destroy the accumu-
lated contaminants. If the carbon cannot be economically
reactivated, the carbon must be discarded and may have to be
treated and disposed of as a hazardous waste. In some cases,
the influent to GAC treatment must be pretreated to prevent
excessive head loss. Residues from pretreatment (e.g. filtered
suspended solids) must be treated or disposed. Solids collected
from backwashing may need to be treated and disposed of as a
hazardous waste.
Site Requirements
GAC equipment generally has small space requirements
and sometimes can be incorporated in mobile units. The
rapidity of startup and shutdown also makes GAC amenable to
mobile treatment Carbon beds or columns can be skid-mounted
and transported by truck or rail [2, p. 5-19].
As previously stated, spent carbon from the treatment of
streams containing hazardous substances is generally considered
hazardous, and its transportation and handling requires that a
site safety plan be developed to provide for personnel protection
and special handling measures. Storage may have to be provided
to hold the GAC-treated liquid until its acceptability for release
has been determined. If additional treatment is required, ad-
equate space must be provided for these systems.
4
Engineering Bulletin: Granular Activated Carbon Treatment
-------
Performance Data
Performance data on full-scale CAC systems have been
reported by several sources including equipment vendors.
Data on CAC systems at several Superfund sites and other
cleanup sites are discussed in this section. The data presented
for specific contaminant removal effectiveness were obtained
from publications developed by the respective CAC system
vendors. The quality of this information has not been deter-
mined; however, it does give an indication of the efficiency of
CAC.
A CAC system was employed for leachate treatment at the
Love Canal Superfund site in Niagara Falls, New York. The
results of this operation are listed in Tables 3 and 4 [11].
Table 5 summarizes a number of experiences by Calgon
Corporation in treating contaminated groundwater at many
other non-Superfund sites. Table 5 identifies the sources of
contamination along with operating parameters and results
[12]. While these sites were not regulated under CERCLA, the
type and concentration of contaminants are typical of those
encountered at a Superfund site.
The Verona Well Field Superfund site in Battle Creek, Michi-
gan used CAC as a pretreatment for the air stripper. This
arrangement reduced the influent concentrations which allowed
the air stripper to comply with the National Pollution Discharge
Elimination System (NPDES) permit. The system had two paral-
lel trains: a single unit and two units in series. Approximately
one-third of the total flow was directed to the first train while
the remaining flow went to the other train. Performance data
for removal of total volatile organic compounds (7VOC) on
selected operating days are given in Table 6 [13].
A remediation action at the U.S. Coast Guard Air Station in
Traverse City, Michigan, resulted in CAC being used to treat
contaminated groundwater. The groundwater was pumped
from the extraction well system to the CAC system. The treated
water was then discharged to the municipal sewer system.
Concentrations of toluene in the monitoring wells were reduced
from 10,329 parts per billion (ppb) to less than 10 ppb in
approximately 100 days [14].
Technology Status
CAC is a well-proven technology. It has been used in the
treatment of contaminated groundwater at a number of Super-
fund sites. Carbon adsorption has also been used as a polishing
step following other treatment units at many sites. In 1988, the
number of sites where activated carbon was listed in the Record
of Decision was 28; in 1989, that number was 38.
Costs associated with CAC are dependent on waste stream
flow rates, type of contaminant, concentrations, and site and
timing requirements. Costs are lower with lower concentration
levels of a contaminant of a given type. Costs are also lower at
higher flow rates. At liquid flow rates of 100-million gallons per
day (mgd), costs range from $0.10-1.50/1,000 gallons treated.
At flow rates of 0.1 mgd, costs increase to $1.20 - 6.30/1,000
gallons treated [12].
Table 3
Love Canal Leachate Treatment System0 (March 1979) [11]
Priority Pollutant
Compounds Identified
Hexachlorobutadiene
1 ,2,4-trichlorobenzene
Hexachlorobenzene
a-BHC
7-BHC
P-BHC
Heptachlor
Phenol
2,4-dichlorophenol
Methylene chloride
1,1-dichloroethylene
Chloroform
Carbon tetrachloride
Trichloroethylene
Dibromochloromethane
1 ,1 ,2,2-tetrachloroethylene
Chlorobenzene
Carbon System
Influent
109
23
32
184
392
548
573
4,700°
10
180
28
540
92
240
21
270
1,200
Carbon System
Effluent
<20
<20
<20
<0.01
0.12
<0.01
<0.01
<5b
<5
<10
<10
<1 0
<1 0 ;
<10
<1 0
<1 0
<1 0
• Samples were analyzed by Recra Research, Inc., according to EPA
protocol dated April 1977 (sampling and analysis procedures of
screening for industrial effluents for priority pollutants).
" The data represent phenol analysis conducted by Calgon in June 1979,
as earlier results were suspect.
Table 4
Love Canal Leachate Treatment System0 (June 1979) [11]
Priority Pollutant
Compounds Identified
2,4,6-trichlorophenol
2,4-dichlorophenol
Phenol
1 ,2,3-trichlorobenzene
Hexachlorobenzene
2-chloronaphthalene
1 ,2-dichlorobenzene
1,3 & 1,4-dichlorobenzene
Hexachlorobutadiene
Anthracene and phenanthrene
Benzene
Carbon tetrachloride
Chlorobenzene
1,2-dichloroethane
1,1,1-trichloroethane
1,1-dichloroethane
1,1,2-trichloroethane
1 , 1 ,2,2-tetrachloroethane
Chloroform
1 , 1 -dichloroethylene
1 ,2-trans-dichloroethylene
1 ,2-dichloropropane
Ethylbenzene
Methylene chloride
Methyl chloride
Chlorodibromomethane
Tetrachloroethylene
Toluene
Trichloroethylene
Raw
Leachate
M-S/'
85
5,100
2,400
870
110
510
1,300
960
1,500
29
28,000
61,000
50,000
52
23
66
780
80,000
44,000
16
3,200
130
590
140
370
29
44,000
25,000
5,000
Carbon System
effluent
M/l
<10
N.D.
<10
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
N.D.
<10
<10
12
N.D.
N.D.
N.D.
<10
<10
<10
N.D.
<10
N.D.
<10
46
N.D.
N.D.
12
<10
N.D.
' Samples were analyzed by Carborundum Corporation according to EPA
protocol dated April 1977 (sampling and analysis procedures for screening
of industrial effluents for priority pollutants).
N.D. = nondetectable.
Engineering Bulletin: Granular Activated Carbon Treatment
-------
Table 5
Performance Data at Selected Sites [12]
' Source of
- Contaminants
Truck spill
Methylene chloride
1,1,1-trichloroethane
Rail car spills
Phenol
Orthochlorophenol
Vinylidine chloride
Ethyl acrylate
Chloroform
Chemical spills
Chloroform
Carbon tetrachloride
Trichloroethylene
Tetrachloroethylene
Dichloroethyl ether
Dichloroisopropyl ether
Benzene
DBCP
1,1,1-trichloroethane
Trichlorotrifloroethane
Cis-1 ,2-dichloroethylene
Onsite storage tanks
Cis-1 ,2-dichloroethylene
Tetrachloroethylene
Methylene chloride
Chloroform
Trichloroethylene
Isopropyl alcohol
Acetone
1,1,1 -trichloroethane
1 ,2-dichloroethylene
Xylene
Landfill site
TOC
Chloroform
Carbon tetrachloride
Gasoline spills, tank leakage
Benzene
Toluene
Xylene
Methyl t-butyl ether
Di-isopropyl ether
Trichloloethylene
Chemical by-products
Di-isopropyl methyl phosphonate
Dichloropentadiene
Manufacturing residues
DDT
TOC
1 ,3-dichloropropene
Chemical landfill
1,1,1-trichloroethane
1,1-dichloroethylene
Typical Influent
Cone.
(mg/l)
21
25
63
100
2-4
200
0.020
3.4
1 30-1 35
2-3
70
1.1
0.8
0.4
2.5
0.42
5.977
.005
0.5
7.0
1.5
0.30-0.50
3-8
0.2
0.1
12
0.5
8.0
20
1.4
1.0
9-11 1
5-7}
6-10 >
0.030-0.035
0.020-0.040
0.050-0.060
1.25
0.45
0.004
9.0
0.01
0.060-0.080
0.005-0.015
Typical Effluent Carbon Usage
Cone. Rate
(\ig/l) (Ib./IOOOgal.)
<1.0 3.9
<1.0 3.9
<1.0 5.8
<1.0 5.8
<10.0 2.1
<1.0 13.3
<1.0 7.7
<1.0 11.6
<1.0 11.6
<1.0 11.6
<1.0 11.6
<1.0 0.45
<1.0 0.45
<1.0 1.9
<1.0 0.7-3.0
<10 1.5
<10 1.5
<1.0 0.25
<1.0 0.8
<1.0 0.8
<100 4.0
<100 1.19
<1.0 1.54
<10.0 1.54
<10.0 1.54
<5.0 1.0
<1.0 1.0
<1.0 1.0
<5000 1.15
<1.0 1.15
<1. 1.15
<1.01
<1 00 Total <1.01
<1.01
<5.0 0.62
<1.0 0.10-0.62
<1.0 0.62
<50 0.7
<10 0.7
<0.5 1.1
1.1
<1.0 1.1
<1.0 <0.45
0.005 <0.45
Total Contact
Time
(min.)
534
534
201
201
60
52
160
262
262
262
262
16
16
112
21
53
53
121
64
64
526
26
36
36
36
52
52
52
41
41
41
214
214
214
12
12
12
30
30
31
31
31
30
30
Engineering Bulletin: Granular Activated Carbon Treatment
-------
Table 6
TVOC Removal with GAC at
Verona Well Superfund Site [13]
REFERENCES
Operating
Day
1
9
16
27
35
42
49
57
69
92
106
238
Influent
feed
Concentration
(PP°)
18,812
12,850
9,290
6,361
7,850
7,643
7,577
5,591
1 0,065
6,000
3,689
4,671
Effluent
Train (1)
Concentration
(ppb)
NA
11
41
260
484
412
405
452
377
444
13
246
Train (2)
Concentration
(pot)
25 i
7
17
426
575
551
524
558
475
509 :
702
263
NA = not available
EPA Contact
Technology-specific questions regarding GAC treatment
may be directed to:
Dr. James Heidman
U.S. Environmental Protection Agency
Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Cincinnati, Ohio 45268
FTS 684-7632 or (513) 569-7632
Acknowlegements
This bulletin was prepared for the U.S. Environmental Pro-
tection Agency, Office of Research and Development (ORD),
Risk Reduction Engineering Laboratory (RREL), Cincinnati, Ohio,
by Science Applications International Corporation (SAIC) under
contract No. 68-C8-0062. Mr. Eugene Harris served as the EPA
Technical Project Monitor. Mr. Gary Baker was SAIC's Work
Assignment Manager. This bulletin was authored by Ms. Mar-
garet M. Groeber of SAIC. The author is especially grateful to
Mr. Ken Dostal and Dr. James Heidman of EPA, RREL, who have
contributed significantly by serving as a technical consultant
during the development of this document.
The following other Agency and contractor personnel have
contributed their time and comments by participating in the
expert review meetings and/or peer reviewing the document:
Dr. John C. Crittenden
Mr. Clyde Dial
Mr. James Rawe
Dr. Walter J. Weber, Jr.
Ms. Tish Zimmerman
Michigan Technological University
SAIC
SAIC
University of Michigan
EPA-OERR
1. Voice, T.C. Activated-Carbon Adsorption. In: Standard
Handbook of Hazardous Waste Treatment and Disposal,
H.M. Freeman, ed. McGraw-Hill, New York, New York,
1989.
2. Mobile Treatment Technologies for Superfund Wastes.
EPA/540/2-86/003 (f), U.S. Environmental Protection
Agency, Washington, D.C., 1986.
3. Weber Jr., W.J. Evolution of a Technology. Journal of the
Environmental Engineering Division, American Society of
Civil Engineers, 110(5): 899-917, 1984.
4. Sontheimer, H., et.al. Activated Carbon for Water
Treatment. DVGW-Forschungsstelle, Karlsruhe, Germany.
Distributed in the US by AWWA Research Foundation,
Denver, CO. 1988.
5. Technology Screening Guide for Treatment of CERCLA
Soils and Sludges. EPA/540/2-88/1004, U.S. Environmen-
tal Protection Agency, Washington, D.C., 1988.
6. A Compendium of Technologies Used in the Treatment
of Hazardous Wastes. EPA/625/8-87/014, U.S. Environ-
mental Protection Agency, Cincinnati, Ohio, 1987.
7. Lenzo, F., and K. Sullivan. Ground Water Treatment
Techniques - An Overview of the State-of-the-art in
America. Paper presented at First US/USSR Conference
on Hydrology. Moscow, U.S.S.R. July 3-5, 1989.
8. Crittenden, J.C. et. al. Using GAC to Remove VOC's From
Air Stripper Off-Gas. Journal AWWA, 80(5):73-84, May
1988.
9. Stenzel, M.H. and Utpal Sen Gupta. Treatment of
Contaminated Groundwaters with Granular Activated
Carbon and Air Stripping. Journal of the Air Pollution
Control Association, 35(12): 1304-1309, 1985.
10. Stenzel, M.H. and J.G. Rabosky. Granular Activated
Carbon - Attacks Groundwater Contaminants. Marketing
Brochure for Calgon Carbon Corporation, Pittsburgh,
Pennsylvania.
11. McDougail, W.J. et. al., Containment and Treatment of
the Love Canal Landfill Leachate, Journal WPCF, 52(12):
2914-2923,1980.
12. O'Brien, R.P. There is an Answer to Groundwater
Contamination. Water/Engineering & Management,
May 1983.
13. CH2M Hill. Thomas Solvent-Raymond Road Groundwater
Extraction Well Treatment System Monitoring Report.
June 1988.
14. Sammons, J.H. and J.M. Armstrong. Use of Low Flow
Interdiction Wells to Control Hydrocarbon Plumes in
Groundwater. In: Proceedings of the Natural Conference
on Hazardous Wastes and Hazardous Materials Control
Research Institute. Silver Spring, Maryland, 1986.
15. Adams, J.Q. and R.M. Clark. Evaluating the Costs of
Packed Tower Aeration and GAC for Controlling Selected
Organics. Journal AWWA, 83(1 ):49-57, January 1991.
Engineering Bulletin: Granular Activated Carbon Treatment
-------
United States Center for Environmental Research BULK RATE
Environmental Protection Information POSTAGE & FEES PAID
Agency Cincinnati, OH 45268 EPA
PERMIT No. C-35
Official Business
Penalty for Private Use $300
-------
Section 9
-------
AQUEOUS BIOLOGICAL TREATMENT
STUDENT PERFORMANCE OBJECTIVES
At the conclusion of this unit, students will be able to:
1. Define biodegradation
2. Define bioremediation
3. List three types of liquid applications where aqueous
biological treatment (ABT) may be used
4. List two advantages of ABT systems
5. List two disadvantages of ABT systems
6. State four different types of microorganisms that actively
biodegrade wastes
7. Define aerobic and anaerobic respiration
NOTE: Unless otherwise stated, the conditions for
performance are using all references and materials
provided in the course, and the standards of
performance are without error.
7/95
-------
STUDENT PERFORMANCE OBJECTIVES (cont.)
8. Describe one important factor about each of the following
terms as it relates to ABT systems and operations:
a. Waste composition
b. Water solubility
c. Biodegradability
d. Modes of respiration
e. Adenosine triphosphate production
f. Temperature
g. Nutrients
h. pH
i. Microbial population dynamics
9. Describe five commonly used ABT processes
10. Describe the significance of the following tests commonly
used in water treatment plants:
a. Biochemical oxygen demand (BOD)
b. Chemical oxygen demand (COD)
c. Total organic carbon (TOC)
11. Describe the relationship of BOD, COD, and TOC tests to
ABT.
NOTE: Unless otherwise stated, the conditions for
performance are using all references and materials
provided in the course, and the standards of
performance are without error.
Aqueous Biological Treatment 7/95
-------
NOTES
AQUEOUS
BIOLOGICAL
TREATMENT
S-1
DEFINITIONS
Biodegradation - all processes where
microorganisms break down compounds
Bioremediation - biodegradation
processes in the soil cy\ QC****^
D
S-2
APPLICATIONS
• Leachate
• Dredging/excavation
• Runoff/overflow
• Dewatering
• Groundwater
S-3
7/95
Aqueous Biological Treatment
-------
NOTES
ADVANTAGES OF
BIODEGRADATION
Destructive treatment
Usually lower cost
Onsite treatment
Natural organisms OAL
S-4
DISADVANTAGES OF
BIODEGRADATION
May require pretreatment or additional
treatment
Sludge generation/solids treatment and
handling
Complex evaluation
Long term
s-s
MICROORGANISMS
Bacteria
Viruses
Fungi
Protozoans
Algae
3-8
Aqueous Biological Treatment
7/95
-------
\r
\
NOTES
COMMON AQUEOyS
TREATMENT SYSTEMS
• Aerob
- Trickli
ters
d ge
rated laa,o£*re/oxidation ponds
- Rotaiiafl bielogibal contactors
REMOVAL PROCESSES
Physical, Chemical, and Biological
Volatilization
Air tourc* for mixing and for oxygen
S-7
s-e
FACTORS THAT AFFECT
BIODEGRADATION
Waste composition
Water solubility CL
Biodegradability
Modes of respiration
Adenosine triphosphate (ATP) production
3-9
7/95
Aqueous Biological Treatment
-------
NOTES
FACTORS THAT AFFECT
BIODEGRADATION (cont.)
• Temperature
• Nutrients
• pH &*-
• Microbial population dynamics
8-10
WASTE COMPOSITION
• Aerobic
- Gaseous compounds
- Aliphatic hydrocarbons
- Sulfides and cyanides
• Anaerobic organic waste mixtures
- Nonhalogenated hydrocarbons
- HighpH
S-11
SOLUBILITY
• Bioavailability
• Lipophilic/hydrophilic
O((L&iikCi (jsoAy^. W/i«fi
• Polarity ^pM
S-12
Aqueous Biological Treatment
7/95
-------
BIODEGRADABILITY
Bioavailability
Bioaccumulation/bioconcentration
Toxicity of compound
Measurement of biochemical oxygen
demand (BOD)
8-13
MODES OF RESPIRATION
Anaerobic (fermentation) uses nitrogen
_ .. microorganisms
CxHy — > CO2 + CH4 + Biomass
nutrients
S-14
MODES OF RESPIRATION
Aerobic
CxHy + 02 m^!^"> CO2 + H2O + Biomass
nutrients
S-1S
NOTES
7/95
Aqueous Biological Treatment
-------
NOTES
ATP PRODUCTION
Anaerobic (less efficient process)
C6H12Oe+ 12NO; —»6CO,+ 6H2O + 12NOJ
Aerobic
C9H1206 + 6O2—>• + 6CO2 + 6H2O
S-18
TEMPERATURE
Organisms have higher metabolic rate at
slightly elevated temperature
Too high causes cell death
Aerobic (68-95°F)
Anaerobic (86-158°F)
S-17
NUTRIENTS
• Essential nutrients: C, H, N, O, P, S
• Nitrogen and phosphorus are usually
deficient in systems -
Added to enhance microbes
S-18
Aqueous Biological Treatment
7/95
-------
NOTES
pH
Maintained so organisms can survive
Optimal pH is between 6 and 8
Anaerobes prefer basic conditions
(PH £9)
8-19
MICROBIAL POPULATION
DYNAMICS
Chemical concentration
Under stable
Lag time
Time
S-20
COMMON AQUEOUS TREATMENT
SYSTEMS
• Aerobic
- Trickling filters
- Activated sludge
- Aerated lagoons/oxidation ponds
- Rotating biological contactors
• Anaerobic
- Digestors/bioreactors
S-21
7/95
Aqueous Biological Treatment
-------
NOTES
TRICKLING FILTERS
Aerobic
Attached growth
System components
- Equalization basin/settling tank
- Filter medium
- Clarifier
- Recirculation line
• Residual biomass
S-22
ACTIVATED SLUDGE
Aerobic
Suspended growth
System components
- Equalization tank/settling tank
- Aeration basin
- Clarifier
Residual biomass
- Recycled or treated
3-23
AERATED LAGOON
Aerobic
Suspended growth
Oxidation ponds/ditches and algal ponds
, ,. Wk~ hW^'"'1'
Indigenous or exogenous
Aeration is greatest expense
Residual biomass
S-24
Aqueous Biological Treatment
7/95
-------
NOTES
ROTATING BIOLOGICAL CONTACTORS
Aerobic
• Attached growth
• System components
- Disks
- Clarifier
• Biomass
S-2S
DIGESTORS/BIOREACTORS
Anaerobic
• Suspended growth
• System components
- Equalization tank/settling tank
- Digestor unit
- Gas recovery unit
- Clarifier
• Biomass
S-28
ABT SUMMARY
• Microbial population
• Aeration
- Respiration
- Mixing
• Nutrients, pH, and temperature
• Chemical characteristics dl tytftfa
\]
• Residual biomass iG^sW?
4-
i\V\(i,UA
S-27
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Aqueous Biological Treatment
-------
REFERENCES
Hammer, M. 1986. Water and Wastewater Technology. John Wiley and Sons, New York.
Major, D., and J. Fitchko. 1990. Emerging On-Site and In-Situ Hazardous Waste Treatment
Technologies. Pudvan Publishing Co., Inc., Northbrook, IL.
Nalco Chemical Company. 1988. The Nalco Water Handbook. Second Edition. Frank N.
Kemmer, Ed. McGraw-Hill, Inc., New York.
Raven, P., and G.B. Johnson. 1989. Biology. Second Edition. Times Mirror/Mosby College
Publishing, St. Louis, MO.
U.S. EPA. 1986. Control of Organic Substances in Water and Wastewater. EPA-600/8-83-011.
U.S. Environmental Protection Agency, Office of Research and Development, Washington, DC.
U.S. EPA. 1992a. A Citizen's Guide to Using Indigenous and Exogenous Microorganisms in
Bioremediation. EPA/542/F-92/009. U.S. Environmental Protection Agency, Office of Solid Waste
and Emergency Response, Washington, DC.
U.S. EPA. 1992b. Engineering Bulletin: Rotating Biological Contactors. U.S. Environmental
Protection Agency, Office of Emergency and Remedial Response, Washington, DC.
U.S. EPA. 1993. Guide to Conducting Treatability Studies Under CERCLA: Biodegradation
Remedy Selection. EPA/540/R-93/519a. U.S. Environmental Protection Agency, Office of Solid
Waste and Emergency Response, Washington, DC.
Aqueous Biological Treatment 10 7/95
-------
United States
Environmental Protection
Agency
Off ice of
Solid Waste and
Emergency Response
EPA/542/F-92/009
March 1992
f/EPA
A Citizen's Guide to Using
Indigenous And Exogenous
Microorganisms In Bioremediation
Technology Innovation Office
.Technology Fact Sheet
CONTENTS
Page
What I*
Bioremediation? 1
What Ar* Indigenous
And Exogenous
Microorganisms? 1
How Am Indigenous
Microorganisms Used? 2
How Ar* Exogenous
Microorganisms Used? 2
Which Sites Are
Appropriate For
Indigenous And/Or
Exogenous
Microorganisms?
For More Information
What Is Bioremediation?
Bioremediation uses naturally occurring
microorganisms (yeast, fungi and/or
bacteria) to degrade — break down —
hazardous substances into less toxic or
nontoxic substances. Microorganisms,
just like humans, eat and digest organic
substances for nutrients and energy.
Certain microorganisms can digest
organic substances that are hazardous to
humans. The organic contaminants
degrade into harmless products
consisting mainly of carbon dioxide and
water. Some examples of organic
contaminants include fuels, such as oil
spills, and solvents.
Microorganisms must thrive in order for
bioremediation to take place. In
addition to the food source provided by
the organic contaminants, some
microorganisms require additional
nutrients. To help the microorganisms
survive, several bioremediation
technologies have been developed. The
specific bioremediation technology used
is determined by the type of micro-
organisms present, as well as the site
conditions. The types of micro-
organisms present are an important
consideration because different
microorganisms degrade different types
of compounds and survive under
different conditions.
What Are Indigenous
And Exogenous
Microorganisms?
Indigenous microorganisms are those
microorganisms which are native to the
site. To stimulate the growth of these
indigenous microorganisms, the soil
conditions, such as temperature, pH,
and oxygen and nutrient content, may
need to be adjusted.
If the microorganisms needed to
degrade the contaminant are not present
in the soil, microorganisms from other
locations, whose effectiveness has been
tested in laboratories, are added to the
contaminated soil. These are called
exogenous microorganisms. The soil
conditions sometimes need to be
adjusted to ensure that the exogenous
microorganisms will thrive.
indigenous and Exogenous Microorganisms Profile
Indigenous microorganisms are already present at the site to degrade the organic contaminants Into
nonhazardous substances.
Exogenous microorganisms are not native to the site. These microorganisms can be cultured, In a lab or
on site, to degrade contaminants.
Pnxtocedbydi*
^ Printed on Recycled Paper
-------
What Other Industries Use
Microorganisms?
In addition to degrading hazardous substances,
microorganisms have a long history of uss by a
variety of Industries. For example, the medical
Industry uses a fungus to produce the antbiotle
penicillin, which Is used to destroy harmful
bacteria. The beer industry uses yeast during ;
the fermentation process to make alcoholic
beverages. - :..." ' '":•••'•' :•". •'*,:.•"•
•• • ' • ' ' •'' _>
How Are Indigenous Microorganisms
Used?
Figure 1, below, illustrates the use of both indigenous and
exogenous microorganisms. In most sites undergoing
bioremediation, indigenous microorganisms are used. The
process begins by sampling the contaminated soil. These
samples are taken to a laboratory and studied. In the
laboratory, the types of microorganisms present in the
contaminated soil and their optimal living conditions are
determined. If the indigenous microorganisms are able to
successfully degrade the contaminant, exogenous micro-
organisms are not needed.
If the soil conditions are right, the indigenous micro-
organisms will use the contaminants in the soil as a food
source and convert them to nonhazardous substances. The
main end products of this conversion reaction are carbon
dioxide and water (CO2+ H,O). In order to see if the
bioremediation reaction is indeed occurring, the level of end
products (CO2+ HjO) is monitored for an increase in levels
and the contaminants are checked for a decrease in levels.
If the reaction is not occurring, the soil conditions may need
adjusting.
Once the degradation of the contaminants is completed,
most of the indigenous microorganisms will die because
they have used all of their food source. The dead micro-
organisms pose no contamination risk because they have
already degraded the contaminants into nontoxic substances.
How Are Exogenous Microorganisms
Used?
As with indigenous bioremediation, the first step in this
process is soil sampling. The samples are taken to a
laboratory and studied. Here, the types of microorganisms
are identified. If microorganisms capable of degrading the
contaminants are not present, then exogenous micro-
organisms may be considered for introduction into the soil
Figure 1
Use of Indigenous and Exogenous Microorganisms
WgOr fr
Extract Soil ff
/tiY
Examine Samples
POC inOMOQOttt
Microorganism* And
Emrtronmantal
Condition*
tamlnant (e.g. oil)
Useful Indigenous
MIcntMM^anlafna
Pm«nt In Th* Soil
Useful Organisms
Obtain And Culture
Uaatul Microorganism*
JL
Add Uaaful Exogenous
Microorganisms to Soil
BIOREHEDIATION OCCURS IN THE SOU. I
tUcroorgantemaEatOtt
Digest Oil
and Convert M To CO, « HfO
-------
However, the toxicity of the soil needs to be determined to
ensure that the exogenous organisms will survive. Although
they are not naturally present at the contaminated site, these
exogenous microorganisms are naturally occurring at other
locations.
The exogenous microorganisms are taken from other
locations and 'cultured' in the laboratory. This means the
microorganisms are placed in optimal living conditions (for
example, perfect temperatures and an abundant source of
nutrients) so that they can multiply. When they have
multiplied to great numbers, these microorganisms can be
taken to the site and added to the contaminated soil.
If the soil conditions are right, the indigenous micro-
organisms will use the contaminants in the soil as a food
source and convert them to nonhazardous substances. The
main end products of this conversion reaction are carbon
dioxide and water (C02+ HjO). In order to see if the
bioremediation reaction is indeed occurring, the level of end
products (CO2+ HjO) is monitored for an increase in levels
and the contaminants are checked for a decrease in levels.
If the reaction is not occurring, the soil conditions may need
adjusting.
Once the degradation of the contaminants is completed,
most of the exogenous microorganisms will die because
they have used all of their food source. The dead micro-
organisms pose no contamination risk because they have
already degraded the contaminants into nontoxic substances.
Exogenous microorganisms will not permanently affect the
soil's composition.
^""^" *~^~™^~"""^""™*"""™"™"""™"™™^"^"™**v.
What Is An Innovative Treatment
Technology?
Tnatmant technologies are processes applied
to the treatment of hazardous wast* or
contaminated materials to permanently alter
their condition through chemical, biological, or
physical means. Technologies that have been
tested, selected or used for treatment of
hazardous waste or contaminated materials but
lack well-documented cost and performance
data under a variety of operating conditions are
called Innovative treatment technologies.
Are Genetically Engineered
Microorganisms Being Used?
The genetic engineering of microorganisms for
bioremediation Is still In the research and
development stages and has not yet been used
commercially In the United States. As the
knowledge end usee of genetic engineering '..
Increase, It may be ejrlmpoftsnt way to enhance
bioremediation technology. Uses of genetically
engineered microorganisms-.for bioremediation
•re regulated by the Toxic Substances Control
Act
x^
Which Sites Are Appropriate For
Indigenous And/Or Exogenous
Microorganisms?
Indigenous bioremediation, exogenous bioremediation, or a
combination of the two can be useful depending upon site
conditions. Relying on indigenous microorganisms is
appropriate if useful strains are present and concentrated in
the area of contamination. If indigenous organisms are
already surviving in the original soil conditions, the process
of optimizing the soil's conditions for these microorganisms
is not as complicated as it is for exogenous microorganisms.
Using indigenous microorganisms also tends to be less
expensive than culturing and introducing exogenous micro-
organisms into the soil. For all of these reasons, most
bioremediation technologies make use of indigenous micro-
organisms whenever possible. However, exogenous micro-
organisms are needed when useful microorganisms are not
already present
A thorough scientific assessment of the contaminated soil
and the soil conditions must be performed to determine
whether indigenous or exogenous microorganisms would
make the bioremediation more effective.
-------
For More Information
EPA prepared this tact sheet to provide basic Information on Indigenous and exogenous microorganisms.
Additional technical reports arc listed below. The document with a "PS" designation to available by contact-
Rig the National Technical Information Service (NT1S) at 1-600-336-4700. Mall orders can be sent to:
National Technical information Service
Springfield, VA 22161
Other documents may be obtained by contacting:
Center for Environmental Research Information
i 26 West Martin Luther King Drive
Cincinnati, OH 45268
(513)569-7562
There may be a charge for these documents.
• Btoremedlatton of Contaminated Surface Son, PB90-164047.
• Engineering Bulletin-Slurry Btodegradatton, EPA/540/2-90/016.
• Understanding Btoremedlatlon: A Guide Book for Citizens, EPA 540/2-91/002.
NOTICE: This t»a ah»«t a iniw^ed io/»fy 13 ganenl guidtncf tnd Inlorrntliafi. ttisnotlntanifd. nor can it b»niifd upon, to cnuetny rights anlonottilt by try
ptrty in Ittgution with the Urmd Sams. Th« Agency tto r»s«r^ fa right U etog» ^ gtrt*& tt fry tim» without pubfc nooc».
A •US.QovwniKntPiMngOffleK 1902—64MeMOOOQ
-------
United States
Environmental Protection
Agency
Office of Emergency and
Remedial Response
Washington, DC 20460
Office o»
Research and Development
Cincinnati, OH 45268
Superfund
EPA/540/S-92/D07
October! 992
Engineering Bulletin
&EPA Rotating Biological Contactors
Purpose
Section 121(b) of the Comprehensive Environmental Re-
sponse, Compensation, and Liability Act (CERCLA) mandates the
Environmental Protection Agency (EPA) to select remedies that
"utilize permanent solutions and alternative treatment technolo-
gies or resource recovery technologies to the maximum extent
practicable" and to prefer remedial actions in which treatment
"permanently and significantly reduces the volume, toxichy, or
mobility of hazardous substances, pollutants, and contaminants
as a principal element" The Engineering Bulletins are a series of
documents that summarize the latest information available on
selected treatment and site remediation technologies and related
issues. They provide summaries of and references for the latest
information to help remedial project managers, on-scene coor-
dinators, contractors, and other site cleanup managers under-
stand the type of data and site characteristics needed to evalu-
ate a technology for potential applicability to their Superfund or
other hazardous waste she. Those documents that describe in-
dividual treatment technologies focus on remedial investigation
scoping needs. Addenda will be issued periodically to update
the original bulletins.
Abstract
Rotating biological contactors (RBCs) employ aerobic fixed-
film treatment to degrade either organic and/or nitro-
genous (ammonia-nitrogen) constituents present in aqueous
waste streams. Treatment is achieved as the waste passes by the
media, enabling fixed-film systems to acclimate biomass capable
of degrading organic waste [1, p. 91]*. Fixed-film RBC reactors
provide a surface to which soil organisms can adhere; many in-
digenous soil organisms are effective degraders of hazardous
wastes.
An RBC consists of a series of corrugated plastic discs
mounted on a horizontal shaft As the discs rotate through the
aqueous waste stream, a microbial slime layer forms on the sur-
face of the discs. The microorganisms in this slime layer degrade
the waste's organic and nitrogenous constituents. Approximately
40 percent of the RBC's surface area is immersed in the waste
stream as the RBC rotates through the liquid. The remainder of
the surface area is exposed to the atmosphere, which provides
oxygen to the attached microorganisms and facilitates oxidation
of the organic and nitrogenous contaminants [2, p. 6]. In gen-
eral, the large microbial population growing on the discs pro-
vides a high degree of waste treatment in a relatively short time.
Although RBC systems are capable of performing organic re-
moval and nitrification concurrently, they may be designed to
primany provide either organic removal or nitrification singly [3,
P. 1-2].
RBCs were first developed in Europe in the 1950s [1, p. 6].
Commercial applications in the United States did not occur un-
til the late 1960s. Since then, RBCs have been used in the United
States to treat municipal and industrial wastewaters. Because bio-
logical treatment converts organics to innocuous products such
as COy investigators have begun to evaluate whether biologi-
cal treatment systems like RBCs can effectively treat liquid waste
streams from Superfund sites. Treatabifity studies have been per-
formed at at feast three Superfund sites to evaluate the effective-
ness of this technology at removing organic and nitrogenous
constituents from hazardous waste leachate. A full-scale RBC
treatment system is presently operating in at least one Super-
fund she in the United States.
Technology Applicability
Research demonstrates that RBCs can potentially treat aque-
ous organic waste streams from some Superfund sites. During
the treatabilrty studies for the Stringfeilow, New Lyme, and Mover
Superfund sites, RBC systems efficiently removed the major or-
ganic and nitrogenous constituents in the teachates. Because
waste stream composition varies from site to site, treatabilrty test-
ing to determine the degree of contaminant removal is an es-
sential element of the remedial action plan. Although recent
Superfund applications have been limited to the treatment of
landfill teachates, this technology may be applied to groundwa-
ter treatment [4].
In general, biological systems can degrade only the soluble
fraction of the organic contamination. Thus the applicability of
RBC treatment is ultimately dependent upon the solubility of the
contaminant RBCs are generally applicable to influents contain-
ing organic concentrations of up to 1 percent organics, or be-
tween 40 and 10,000 mg/l of SBOD. (Note: Soluble biochemi-
cal oxygen demand, or SBOD, measures the soluble fraction of
the biodegradable organic content in terms of oxygen demand.)
RBCs can be designed to reduce influent biochemical oxygen de-
mand (BOD) concentrations below 5 mg/l SBOD and ammo-
•[reference number, page number]
-------
Tablel
Effectiveness of RBCs on General Contaminant
Groups for Liquid Waste Streams
Contaminant Croups
Effectiveness
Halogenated volatile*
Halogenated semivolatiles
Nonhalogenated volatites
Nonhalogenated semivolatiles
PCBs
Pesticides
Dioxins/Furans
Organic cyanides
Organic corrosives
T
O
T
V
Volatile metals
Nonvolatile metals
Asbestos
Radioactive materials
Inorganic corrosives
Inorganic cyanides
O
O
O
a
o
V
Oxidizers
Reducers
O
O
• Demonstrated Effectiveness: Successful treatabiflty test at some scale com-
pleted.
T Potential Effectiveness: Expert opinion that technology will work.
Q No Expected Effectiveness: Expert opinion that technology will not work.
nia-nitrogen (NH,-N) levels below 1.0 mg/l [5, p. 2] [6, p. 60].
' RBCs are effective for treating solvents, halogenated organics,
acetone, alcohols, phenols, phthalates, cyanides, ammonia, and
petroleum products [7, p. 6] [8, p. 69]. RBCs have fully nitrified
leachates containing ammonia-nitrogen concentrations up to
700 mg/l [6, p. 61].
The effectiveness of RBC treatment systems on general con-
taminant groups is shown in Table 1. Examples of constituents
within contaminant groups are provided in "Technology Screen-
ing Guide for Treatment of CERCLA Soils and Sludges" [9]. Table
1 is based on the current available information or professional
judgment where no information was available. The proven ef-
fectiveness of the technology for a particular site or waste does
not ensure that it will be effective at all sites or that the treat-
ment efficiencies achieved will be acceptable at other sites. For
the ratings used for the table, demonstrated effectiveness means
that, at some scale, treatabiiity was tested to show the technol-
ogy was effective for that particular contaminant group. The rat-
ings of potential effectiveness or no expected effectiveness are
based upon expert judgment Where potential effectiveness is
indicated, the technology is believed capable of successfully treat-
ing the contaminant group in a particular medium. When the
technology Is not applicable or will probably not work for a par-
ticular combination of contaminant group and medium, a no
expected effectiveness rating is given.
Limitations
Although RBCs have proven effective in treating waste
streams containing ammonia-nitrogen and organics, they are not
effective at removing most inorganics or non-biodegradable or-
ganics. Wastes containing high concentrations of heavy metals
and certain pesticides, herbicides, or highly chlorinated organ-
ics can resist RBC treatment by inhibiting microbial activity. Waste
streams containing toxic concentrations of these compounds
may require pretreatment to remove these materials prior to RBC
treatment [10, p. 3].
RBCs are susceptible to excessive biomass growth, particu-
larly when organic loadings are elevated. If the biomass fails to
slough off and a blanket of biomass forms which is thicker than
90 to 125 mils, the resulting weight may damage the shaft and
discs. When necessary, excess biofilm may be reduced by either
adjusting the operational characteristics of the RBC unit (e.g., the
rotational speed or direction) or by employing air or water to
shear off the excess biomass [11, p. 2].
In general, care must be taken to ensure that organic prl-
lutants do not volatilize into the atmosphere. To control their
release, gaseous emissions may require offgas treatment [12, p.
31].
All biological systems, including RBCs, are sensitive to tem-
perature changes and experience drops in biological activity at
temperatures lower than 55°F. Covers should be employed to
protect the units from colder climates and extraordinary weather
conditions. Covers should also be used to protect the plastic discs
from degradation by ultraviolet light to inhibit algal growth, and
to control the release of volatiles [13]. In general, organic deg-
radation is optimum at a pH between 6 and 8.5. Nitrification
requires the pH be greater than 6 [6, p. 61].
Additionally, nutrient and oxygen deficiencies can reduce
microbial activity, causing significant decreases in biodegrada-
tion rates [14, p. 39], Extremes in pH can limit the diversity of
the microbial population and may suppress specific microbes
capable of degrading the contaminants of interest Fortunately,
these variables can be controlled by modifying the system de-
sign.
Technology Description
A typical RBC unit consists of 12-foot-diameter plastic discs
mounted along a 25-foot horizontal shaft The total disc surface
area is normally 100,000 square feet for a standard unit and
150,000 square feet for a high density unit Figure 1 is a dia-
gram of a typical RBC system.
As the RBC slowly rotates through the groundwater or
leachate at 1.5 rpm, a microbial slime forms on the discs. These
microorganisms degrade the organic and nitrogenous contami-
nants present in the waste stream. During rotation, approxi-
mately 40 percent of the discs' surface area is in contact with the
aqueous waste while the remaining surface area is exposed to
the atmosphere. The rotation of the media through the atmo-
sphere causes the oxygenation of the attached organisms. When
Engineering Bulletin: Rotating Biological Contactors
-------
Offgas
Treatment
t
Figure 1
Typical RBC Plant Schematic (12)
Offgas
Treatment
t
Offgas
Treatment
Primary
Treatment
Secondary
Clarifier
*
Solids
Disposal
operated properly, the shearing motion of the discs through the
aqueous waste causes excess biomass to shear off at a steady rate.
Suspended biological solids are carried through the successive
stages before entering the secondary clarifier [2, p. 13.101 ].
Primary treatment (e.g., clarifiers or screens), to remove ma-
terials that could settle in the RBC tank or plug the discs, is often
essential for good operation. Influents containing high concen-
trations of floatabtes (e.g., grease, etc) will require treatment us-
ing either a primary clarifier or an alternate removal system [11,
p. 2].
The RBC treatment process may involve a variety of steps,
as indicated by the block diagram in Figure 2. Typically, aque-
ous waste is transferred from a storage or equalization tank (1)
to a mixing tank (2) where chemicals may be added for metals
precipitation, nutrient adjustment, and pH control. The waste
stream then enters a clarifier (3) where the solids are separated
from the liquid. The effluent from the clarifier enters the RBC
(4) where the organics and/or ammonia are converted to innocu-
ous products. The treated waste is then pumped into a second
clarifier (5) for removal of the biological solids. After secondary
clarification the effluent enters a storage tank (6) where, depend-
ing upon the contamination remaining in the effluent, the waste
may be stored pending additional treatment or discharged to a
sewer system or surface stream. Throughout this treatment pro-
cess the offgases from the various stages should be collected for
treatment (7). The actual treatment train will, of course, depend
upon the nature of the waste and will be selected after the
treatability study is conducted.
Staging, which employs a number of RBCs in series, en-
hances the biochemical kinetics and establishes selective biologi-
cal cultures acclimated to successively decreasing organic load-
Figure 2
Block Diagram of the RBC Treatment Process
A Offgases
Offgas
Treatment
(7)
Aqueous
Waste
Treated
Effluents
Sludge Removal
Engineering Bulletin: Rotating Biological Contactors
-------
ings. As the yvaste stream passes from stage to stage, progres-
sively increasing levels of treatment occur [2, p. 13.105].
In addition to maximizing the system's efficiency, staging
can improve the system's ability to handle shock loads by ab-
sorbing the impact of a shock load in the initial stages, thereby
enabling subsequent stages to operate until the affected stages
recover [15, p. 10.200].
Factors effecting the removal efficiency of RBC systems in-
clude the type and concentration of organics present, hydraulic
residence time, rotational speed, media surface area exposed and
submerged, and pre- and post-treatment activities. Design pa-
rameters for RBC treatment systems indude the organic and hy-
draulic load rates, design of the disc train(s), rotational velocity,
tank volume, media area submerged and exposed, retention
time, primary treatment and secondary darifier capacity, and
sludge production [8, p. 69].
Process Residuals
During primary clarification, debris, grit, grease, metals, and
suspended solids (SS) are separated from the raw influent The
solids and sludges resulting from primary clarification may con-
tain metallic and organic contaminants and may require addi-
tional treatment Primary clarification residuals must be disposed
of in an appropriate manner (e.g., land disposal, incineration,
solidification, etc).
Following RBC treatment the effluent undergoes second-
ary clarification to separate the suspended biomass solids from
the treated effluent Refractory organics may contaminate both
the clarified effluent and residuals. Additional treatment of the
solids, sludges, and clarified effluent may be required. Clarified
secondary effluents which meet the treatment standards are gen-
erally discharged to a surface stream, while residual solids and
sludges must be disposed of in an appropriate manner, as out-
lined above for primary clarification residuals [2, p. 13.120].
Volatile organic compound (VOQ-bearing gases are often
liberated as a byproduct of RBC treatment Care must be taken
to ensure that offgases do not contaminate the work space or
the atmosphere. Various techniques may be employed to con-
trol these emissions, including collecting the gases for treatment
[13].
Site Requirements
RBCs vary in size depending upon the surface area needed
to treat the hazardous waste stream. A single full size unit with
a walkway for access on either side of the unit takes up approxi-
mately 550 square feet [16]. The total area required for an RBC
system is site-specific and depends on the number, size, and con-
figuration of RBC units installed.
Contaminated groundwater, leachates, or waste materials
are often hazardous. Handling and treatment of these materials
requires that a site safety plan be developed to provide for per-
sonnel protection and special handling measures. Storage should
be provided to hold the process product streams until they have
been tested to determine their acceptability for disposal, reuse,
or release. Depending on the site, a method to store waste that
has been prepared for treatment may be necessary. Storage ca-
pacity will depend on waste volume.
Onsite analytical equipment capable of determining site-
specific organic compounds for performance assessment make
the operation more efficient and provide better information for
process control.
Performance Data
Limited information is available on the effectiveness of RBCs
in treating waste from Superfund sites. Most of the data came
from studies done on leachate from the New Lyme, Ohio;
StringfeUow, California; and Moyer, Pennsylvania Superfund sites.
The results of these studies are summarized below.
In order to compensate for the lack of Superfund perfor-
mance data, non-Superfund applications are also discussed. The
majority of the performance data for non-Superfund applications
were obtained from industrial RBC operations. Theoretically this
information has a high degree of application to Superfund
leachate and groundwater treatment
The quality of the information present in this section has not
been determined. The data are included as a general guidance,
and may not be directly transferable to a specific Superfund site.
Good characterization and treatability studies are essential in
further refining and screening of RBC technology.
New Lyme Treatability Study
The EPA performed a remedy selection study on the leachate
from the New Lyme Superfund site located in New Lyme Town-
ship, Ashtabula County, Ohio, to help determine the applicabil-
ity of an RBC to treat hazardous waste from a Superfund site
Samples of leachate collected from various seeps surrounding the
landfill showed that the leachate was highly concentrated. Re-
sults indicated that the leachate contained up to 2,000 mg/l dis-
solved organic carbon (DOC), 2,700 mg/1 SBOD, and 5,200 mg/
I soluble chemical oxygen demand (SCOD) [17, p. 12]. (Note:
SCOD measures the soluble fraction of the organics amenable
to chemical oxidation, as well as certain inorganics such as sul-
fides, sulfites, ferrous iron, chlorides, and nitrites.)
Leachate from the New Lyme site was transported from New
Lyme to a demonstration-scale RBC located at the EPA's Testing
and Evaluation Facility in Gncinnati, Ohio. After an adequate
biomass was developed on the RBC discs using a primary efflu-
ent supplied by Mill Creek Treatment Facility (a local industrial
wastewater treatment facility), the units were gradually accli-
mated to an influent consisting of 100 percent leachate. Results
indicated that within 20 hours the RBC removed 97 percent of
the gross organics, as represented by DOC, from the leachate
(see Figure 3 and Table 2) [18, p. 7], Priority pollutants were
either converted and/or stripped from the leachate during treat-
ment After normal clarification, the effluent from the RBC was
Engineering Bulletin: Rotating Biological Contactors
-------
efigtote for disposal into the sewer system leading to the Mai
Creek fadfty.
Stringfellow Treatability Study
A remedy selection study using an RBC was conducted on
leachate from the Stringfellow Superfund site located in Glen
Avon, California. After the leachate from this site received lime
treatment to remove metal contamination, the leachate was
transported to the EPA's Testing and Evaluation Facility in Cin-
cinnati for testing similar to the New Lyme study. The objective
of this study was to determine whether the leachate from
Stringfellow could be treated economically with an RBC system.
The leachate from this site was generated at a daily rate of
2,500 gallons. Compared to the New Lyme leachate, it con-
tained moderate concentrations of gross organic* with DOC
values of 300 mg/I, SBOD values of 420 mg/l, and SCOD val-
ues of 800 mg/l [4, p. 44].
Results indicated that greater than 99 percent of SBOD was
removed, 65 percent of DOC was removed, and 54 percent
SCOD was removed within four days using the RBC laboratory-
scale treatment system [4, p. 44]. Table 3 presents pertinent
information on the treatment of 100 percent leachate. Since
the DOC and SCOD conversion rates were low, a significant frac-
tion of the refractory organic remained following treatment Ac-
tivated carbon was used to reduce the DOC to limits acceptable
to the Mill Creek Treatment Facility.
figure 3
Disappearance of DOC wtth Time (17, p. 14)
Experiments*
Table 2
Removal of PoOutants from New Lyme Leachate (17, p. 17)
Experiments
SBOD
BODT
DOC
TOC
SCOD
NO,-N
SS
VSS
Volatile PP
Benzene
Toluene
Additional Volatile*
Cis 1,2-Dichloroethene
Xytenes
Acetone
Methyl Ethyl Ketone
Total Organic Halides
Total Toxic Organic*
Influent
(mg/l)
2700
3000
2000
2100
5200
1400
240
0.28
4.9
0.94
2.8
140
470
<0.250
Effluent
(mg/l)
4
6.6
17
19
33
60
6600
2600
<0.002
<0.002
ND
ND
ND
ND
1.2
<0.010
BODT =
NO.-N
VSS.
Total Biochemical Oxygen Demand
= Nitrogen as Nitrate
Volatile Suspended Soilds
• The influent for Experiment 5 consisted of 100 percent leachate and the
bkxnass on the RBCs was acdimated. Nutrient addition was aho employed
(at a rate of 160/5/2 for C/N/P).
Moyer Treatability Study
During a recent remedy selection study, three treatability-
scale RBCs were used to degrade a low-BOD (26 mg/I), high
ammonia (154 mg/I) leachate from the Moyer Landfill Superfund
site in Lower Providence Township near Philadelphia, Pennsyl-
vania [19, p. 971 ]. The leachate has low organic strength (e.g.,
26 mg/l BOD, 358 mg/I COD, and 68 mg/l TOC) which is typi-
cal of an older landfill and it also contains mainly non-biodegrad-
able organic compounds [19, p. 972]. (Note: Total organic car-
bon, or TOC, is a measure of all organic carbon expressed as
carbon.) The abundance of ammonia found in the leachate
prompted investigators to attempt ammonia oxidation with an
RBC system. Relatively low substrate loading rates were em-
ployed during the study (02, 0.4, and 0.6 gpd/square foot of
disc surface area per stage). Ammonia oxidation was essentially
complete (98 percent) and a maximum of 80 percent of the BOD
and 38 percent of the COD in the leachate was oxidized [19, p.
980]. Runs performed using lower loading rates experienced the
largest removals. A limited denitrification study was also per-
formed using an anoxic RBC to treat an RBC effluent generated
during the aerobic segment of the treatability investigation. This
study demonstrated the feasibility of using denitrification to treat
Engineering Bulletin: Rotating Biological Contactors
-------
the nitrate produced by aerobic ammonia oxidation [19, p. 980].
Non-Superfund Applications
The Homestake Mine in Lead, South Dakota has operated
an RBC wastewater treatment plant since 1984. Forty-eight RBCs
treat up to 5.5 million gallons per day (MCD) (21,000 m3) of
discharge water per day. The system was designed to degrade
thkxyanate, free cyanide, and metal-complexed cyanides, to re-
duce heavy metal concentrations, and to remove ammonia,
which is a byproduct of cyanide degradation [20, p. 2]. Eight
parallel treatment trains, utilizing five RBCs in series, were em-
ployed to degrade and nitrify the metallurgical process waters
(see Table 4 for a characterization of the influent). The first two
RBCs in each train were used to degrade the cyanides and re-
move heavy toxic metals and paniculate solids through biologi-
cal adsorption. The last three RBCs employed nitrification to
convert the ammonia to nitrate. Table 5 provides an average
performance breakdown for the system. During its operation,
overall performance improved significantly, as demonstrated by
an 86 percent increase in the systems ability to reduce total ef-
fluent cyanide concentrations (e.g., from 0.45 to 0.06
mg/l). Concurrently, the cost per kg to treat cyanide dropped
from $11.79 to $3.10, white the cost per m3 to treat effluent
decreased by 50 percent [21, p. 9]. In general, the system has
responded well to any upsets or disturbances. Diesel fuels, lu-
bricants, degreasers, biocides, dispersants, and flocculants have
been periodically found in the influent wastewater but normally
only create minor upsets in the performance of the plant Dur-
ing the life of the system, the number of upsets and the biomass's
ability to recuperate have both improved [21, p. 6].
A significant difference between the Homestake system and
the other RBC systems described within the report is that instead
of removing the metals contaminating the wastewater in the
pretreatment stage, metal reduction is accomplished through
bioadsorption during the treatment phase. Bioadsorption of
metals by biological cells is not unlike the use of activated car-
bon, however the number and complexity of binding sites on
the cell wall are enormous in comparison [20, p. 2].
In a study by Israel's Institute of Technology, a laboratory-
scale RBC was used to treat an oil refinery wastewater. The waste-
water had been pretreated using oil-water separation and dis-
solved air flotation. As summarized in Table 6, 91 percent of
the hydrocarbon and 97 percent of the phenol were removed,
as well as 96 percent of the ammonia-nitrogen [22, p. 4]. By
gradually increasing the concentration of phenols present in the
influent (e.g., over a 5 day period) from 5 mg/l to 30 mg/l, the
system demonstrated that it was capable of quickly adapting to
influent changes and higher phenolic loads [22, p. 6]. During
this period, the RBC was able to maintain effluent COD concen-
trations at levels comparable to previous loadings. The system's
resiliency was further demonstrated by its ability to recover from
a major disturbance (e.g., such that effluent COD removal was
interrupted) within 4 days [22, p. 7].
Technology Status
RBCs have been used commercially in the United States since
Tabled
Treatment of 100% Stringfellow Leachate (4. p. 44)
RBC
Leachate Effluent
(mg/l) (mg/l)
SBOD
BOD
DOC
TOC
SCOD
COD
SS
VSS
NHj-N
NOj-N
420 <3.0
440
300 110
310
800 360
840
43
31
3.4
44
Use APC plus
Effluent
(mg/l)
0.9
22
20
22
79
95
23
14
6.3
34
APC * Activated Powered Carbon
COD > Chemical Oxygen Demand
Table 4
Homestake Mine Wastewater Matrix *
Thiocyanate
Total Cyanide
WAD Cyanide
Copper
Ammonia-N
Phosphorus-P
Alkalinity
PH
Hardness
Temperature'C
Decant
Water
(mg/l)
110-350
5.5-65.0
3.10-38.75
0.5-3.1
5-10
0.10-0.20
50-200
7-9
400-500
1 .0-27.2
Mine
Water
(mg/l)
1-33
0.30-2.50
0.50-1.10
0.10-2.65
5.00-19.00
0.10-0.15
150-250
7-9
650-1400
24-33
Influent
Blend
(mg/l)
35-110
0.50-11.50
0.50-7.15
0.15-2.95
6-12
0.10-0.15
125-225
7.5-8.5
500-850
5-25
WAD - Weak Acid Dissociable
•Adapted from reference [20, p. 8]
Table 5
Influent, Effluent and Permit Concentrations at the
Homestake Mines (20, p. 8)
Thiocyanate
Total Cyanides
WAD Cyanide
Total Copper
Total Suspended Soilds
Ammonia-Nitrogen
Influent
(mg/l)
62.0
4.1
2.3
0.56
-
5.60*
Effluent
(mg/l)
<0.5
0.06
<0.02
0.07
6.0
<0.50
Permit
(mg/l)
.
1.00
0.10
0.13
10.0
1.0-3.9
•Ammonia peaks at 25 mg/l within the plant as a cyanide
degradation byproduct
Engineering Bulletin: Rotating Biological Contactors
-------
Table 6
Refinery Wastewater Quality Before and After
RBC Treatment (22, p. 4)
Constituent
COD
BOD
Phenols
Total
Soluble
Total
Soluble
Influent
(mg/l)
715
685
140
128
7.5
Effluent
(mg/l)
197
186
8
6
0.22
Suspended Solids
NH3-N
Total
Volatile
32
29
12.8
7
6
0.48
During the Stringfellow treatability study researchers determined
that by augmenting the existing carbon treatment system with
RBCs, reductions in carbon costs would pay for the RBC plant
within 3.3 years [4, p. 44]. The RBC plant model used to for-
mulate this estimate was a scaled-up version of the pilot unit used
during the treatability study.
EPA Contact
Technology-specific questions regarding rotating biological
contactors may be directed to:
Edward j. Opatken
U.S. EPA Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Cincinnati, Ohio 45268
Telephone: (513) 569-7855
the late 1960s to treat municipal and industrial wastes. In the
past decade, studies have been performed to evaluate the effec-
tiveness of RBCs in treating leachate from hazardous waste sites.
Treatability studies have been performed on leachate from
the Stringfellow, New Lyme, and Moyer Superfund sites. Results
of these studies indicate that RBCs are effective in removing or-
ganic and nitrogenous constituents from hazardous waste
leachate. Additional research is needed to define the effective-
ness of an RBC in treating leachates and contaminated ground-
water and to determine the degree of organic stripping that
occurs during the treatment process. RBCs are being used to
treat leachate from the New Lyme Superfund site.
RBCs require a minimal amount of equipment, manpower,
and space to operate. Staging of RBCs will vary from site to site
depending on the waste stream. The cost to install a single RBC
unit with a protective cover and a surface area of 100,000 to
150,000 square feet ranges from $80,000 to $85,000 [16] [23].
Acknowledgments
This bulletin was prepared for the U.S. Environmental Pro-
tection Agency, Office of Research and Development (ORD), Risk
Reduction Engineering Laboratory (RREL), Cincinnati, Ohio, by
Science Applications International Corporation (SAIQ under
contract No. 68-C8-0062. Mr. Eugene Ham's served as the EPA
Technical Project Monitor. Mr. Gary Baker was SAIC's Work
Assignment Manager. This bulletin was written by Ms. Denise
Scott and Ms. Evelyn Meagher-Hartzell of SAIC.
The following other Agency and contractor personnel have
contributed their time and comments by participating in the
expert review meetings and/or peer reviewing the document
Dr. Robert L. Irvine University of Notre Dame
Mr. Richard A. Sullivan Foth & Van Dyke
Ms. Mary Boyer SAIC
Mr. Cecil Cross SAIC
Engineering Bulletin: Rotating Biological Contactors
•U.S. Government Printing Office: 1992— 648-080/60066
-------
REFERENCES
1. Cheremisinoff, P.L Biological Treatment of Hazardous
Wastes, Sludges, and Wastewater. Pollution Engineering,
May 1990.
2. Envirex, Inc Rex Biological Contactors: For Proven, Cost-
Effective Options in Secondary Treatment Bulletin 315-
13A-51/90-3M.
Design Information on Rotating Biological Contactors,
EPA/600/2-84/106, U.S. Environmental Protection
Agency, June 1984.
Opatken, E.J., H.K. Howard, and J.J. Bond. Stringfellow
Leachate Treatment with RBC Environmental Progress,
Volume 7, No. 1, February 1988.
Walker Process Corporation. EnviroDisc™ Rotating
Biological Contactor. Bulletin 11-S-88.
Opatken, E.J., and J.J. Bond. RBC Nitrification of High
Ammonia Leachates. Environmental Progress, Volume
10, No. 4, February 1991.
Guide to Treatment Technologies for Hazardous
Wastes at Superfund Sites. EPA/540/2-89/052, U.S.
Environmental Protection Agency, March 1989.
Data Requirements for Selecting Remedial Action
Technology. EPA/600/2-87/001, U.S. Environmental
Protection Agency, January 1987.
Technology Screening Guide for Treatment of
CERCLA Soils and Sludges. EPA/540/2-88/004, U.S.
Environmental Protection Agency, 1988.
10. O'Shaughnessy et al. Treatment of Oil Shale Retort
Wastewater Using Rotating Biological Contactors.
Presented at the Water Pollution Control Federation,
55th Annual Conference, St Louis, Missouri, October
1982.
11. Rotating Biological Contactors: U.S. Overview. EPA/
600/D-87/023, U.S. Environmental Protection
Agency, January 1987.
3.
4.
5.
6.
7.
8.
9.
12. Nunno, T.J., and J.A. Hyman. Assessment of Interna-
tional Technologies for Superfund Applications. EPA/
540/2-88/003, U.S. Environmental Protection
Agency, September 1988.
13. Telephone conversation. Steve Oh, U.S. Army Corps
of Engineers, September 4, 1991.
14. Corrective Action: Technologies and Applications. EPA/
625/4-89/020, U.S. Environmental Protection Agency,
September 1984.
15. Lyco, Inc., Rotating Biological Surface (RBS) Waste-
water Equipment: RBS Design Manual. March 1986.
16. Telephone conversation. Gerald Omstein, Lyco
Corporation, September 4, 1991.
17. Opatken, E.J., H.K. Howard, and J.J. Bond. Biologi-
cal Treatment of Leachate from a Superfund Site.
Environmental Progress, Volume 8, No. 1, February
1989.
18. Opatken, E.J.. H.K. Howard, and J.J. Bond. Biological
Treatment of Hazardous Aqueous Wastes. EPA/600/
D-87/184, June 1987.
19. Spengel, D.B., and DA Dzombak. Treatment of Landfill
Leachate with Rotating Biological Contractors: Bench-
Scale Experiments. Research Journal WPCF,VoL 63, No.
7, November/December 1991.
20. WhrtJock, J.L The Advantages of Biodegradation of
Cyanides. Journal of the Minerals, Metals and Materials
Society, December 1989.
21. Whitlock, J.L Biological Detoxification of Precious Metal
Processing Wastewaters. Homestake Mining Co., Lead,
SD.
22. Galil, N., and M. Rebhun. A Comparative Study of RBC
and Activated Sludge in Biotreatment of Wastewater from
an Integrated Oil Refinery. Israel Institute of Technology,
Haifa, Israel.
23. Telephone conversation. Jeff Kazmarek, Envirex Inc,
September 4,1991.
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/540/S-92/007
-------
Section 10
-------
CHEMICAL REACTIONS
AND SEPARATION
STUDENT PERFORMANCE OBJECTIVES
At the conclusion of this unit, students will be able to:
1. List at least two waste characteristics that affect chemical
treatment
2. Describe the following types of inorganic treatment
technologies:
a. Neutralization
b. Precipitation
c. Oxidation and reduction
d. Cyanide destruction
3. Describe the following aqueous contamination separation
techniques:
a. Filtration
b. Reverse osmosis
c. Ion exchange
4. Describe the ultraviolet oxidation process to remove organic
contaminants from aqueous waste.
NOTE: Unless otherwise stated, the conditions for
performance are using all references and materials
provided in the course, and the standards of
performance are without error.
7/95
-------
CHEMICAL
REACTIONS AND
SEPARATION
S-1
CHEMICAL TREATMENTS
Inorganic reactions
- Neutralization
- Precipitation
- Oxidation/reduction
- Cyanide destruction
S-2
CHEMICAL TREATMENTS (cont.)
Separati9n technologies
- Filtratipn
- Microfiltration
- Reverse osmosis
- Ion exchange
S-3
NOTES
7/95
Chemical Reactions and Separation
-------
NOTES
JS$L
INORGANIC REACTIONS
• Aqueous solutions
• Neutralize or make solubles insoluble
• Heat of reaction may be involved
• Solids separated out for disposal
• Effluent may require further treatment
• Less hazardous products result
8-4
WASTE CHARACTERISTICS
AFFECTING TREATABILITY
• Physical form
• Concentration
• Solids content
• Organic contaminants
- Ferrous metals
S-5
NEUTRALIZATION
Concentration and exothermic reactions
Solids and sludges
Corrosion-resistant equipment
Creating water: H+, OH~
Chemical Reactions and Separation
7/95
-------
NOTES
CHEMICAL PRECIPITATION
• Solubility
• Metal hydroxide sludge
• Optimum pH
• Effluent treatment
S-7
s
CHELATION
r- RCH-0
\
M
L- RCH-0
0-CHR -n
\
0-CHR -"
S-8
Chemical
precipitants
Liquid . W/
-•Ux. , ^v^v
I
Precipitator
tank
U.S. EPA 1991
Chemical
(locculants/
settling aids
Flocculation Flocculating
well / paddles
\ n u~\ -
: ,,, \ I I / I
\ t-*J PfflllUlll
-fc. "* k/r*1 ^
U ~U J Baffle
c= =ar^
' ^ Sludge
Flocculator-
clarifier
s-e
UKZ^Sl
7/P5
Chemical Reactions and Separation
-------
NOTES
CHEMICAL TREATMENT USING
REDUCTION / OXIDATION
• Reducer and oxidizer
• Soluble metals nontoxic
• Cr(VI), Pb, and Hg
• Metal hydroxide sludges
• Effluent treatment
s-io
Sample Chemical Reduction
Reducing agent
feed
Effluent
Chroma reduction tank
Chrome precipitation
Hydroxide
sludge
S-11
CYANIDE DESTRUCTION BY
ALKALINE CHLORINATION
• pH sensitive
• Nonselective
- Chlorinated organics
• Metal hydroxide sludges
• Effluent treatment
- Elevated pH
- Chlorinated organics
S-12
Chemical Reactions and Separation
7/95
-------
ALKALINE CHLORINATION
CHEMICAL PROCESS
1) CI2 + NaCN—> CNCI + NaCI
cyanogen sodiurr
chloride chloride
2
chlorine cyanide cyanogen sodium
2) CNCI + 2NaOH —t NaCNO + H2O + NaCI
cyanogen caustic sodium water sodium
chloride soda cyanate chloride
S-13
ALKALINE CHLORINATION
CHEMICAL PROCESS (cont.)
2NaCNO + 3CI2 + 4H2O + 6NaOH
2NaHCO, + N, + 6NaCI + 6H,O
S-14
NOTES
7/95 5 Chemical Reactions and Separation
-------
Sample Chemical Oxidation -
Alkaline Chlorination (Destruction of Cyanide)
Caustic
feed
Cyanide
liquid
feed
Heat
k.
^r^
4
Carbon
column
Effluen
k
1
^ ./•
so,
4 — reaction
Unused chlorine
capture/reaction
Covered, jacketed reactors (Increased destruction
1st Stage 2nd Stage efficiency)
S-15
NOTES
Chemical Reactions and Separation
7/95
-------
NOTES
SEPARATION TECHNIQUES
• Solids settling or flotation and skimming
• Filtration
- Sand
- Plate and frame
- Pressure
- Vacuum
S-18
SEPARATION TECHNIQUES (cont.)
Centrifuge
Hydroclones
S-17
FILTRATION TERMS
• Slurry feed
• Precoat
• Cake
• Filtrate
• Recirculation vs. single pass
S-18
7/95
Chemical Reactions and Separation
-------
NOTES
MICROFILTRATION
• Particles 0.1 microns or larger
• Particles must be insoluble
• Pretreatment normally required
• Waste concentrated in filter cake
• Filtrate may require further treatment
8-19
DUPONT/OBERLIN FILTER
• Precipitation of feed
• "Prefix" filter aid addition
• Tyvek® filter
• Cake formed under pressure
• Cake drying, removal, and collection
• Tyvek® filter cleaning
S-20
DUPONT/OBERLIN MICROFILTRATION TREATMENT SYSTEM
US. EPA 1001
S-21
Chemical Reactions and Separation
7/95
-------
Osmosis
S-22
Reverse Osmosis
Pressure
S-23
NOTES
7/95
Chemical Reactions and Separation
-------
SIMPLIFIED REVERSE OSMOSIS UNIT
Contaminated
water
Treated
water
Back
pressure
device
Concentrated
wastewater
S-24
REVERSE OSMOSIS UNIT
Contaminated
water
Treated
water
Concentrated
wastewater
S-25
NOTES
Chemical Reactions and Separation
10
7/95
-------
REVERSE OSMOSIS SYSTEM
[Storage
tank
NaOH
31
i —
7w-':
Clarifier p
Reverse
osmosis
unit
S-26
NOTES
7/95
11
Chemical Reactions and Separation
-------
NOTES
REVERSE OSMOSIS
Advantages
• Selective ion removal
• Large volumes treated
• Volume of waste for final disposal is low
• Ion recovery is possible
8-27
REVERSE OSMOSIS
Disadvantages
Nondestructive waste disposal required
Membrane damage
S-28
REVERSE OSMOSIS
FLOW RATE
(gpm)
25
50
100
Cost
CAP. COST
($)
69,000
126,000
235,000
O & M COST
( $/yr )
30,000
41 ,000
76,000
S-29
Chemical Reactions and Separation
12
7/95
-------
NOTES
ION EXCHANGE
• Removes low concentrations of soluble
metals
• Recovers concentrated metal streams for
recycling
S-30
ION EXCHANGE (cont.)
Removes cations (+) and anions (-)
Types of materials
- Naturally occurring (zeolites)'
- Synthetic
S-31
ION EXCHANGE LIMITATIONS
pH
Suspended solids
Other organics
S-32
7/95
13
Chemical Reactions and Separation
-------
Ion Exchange
Acid
regenerant
Waste containing.
Compound MX
Removal
M+*H9R
Regeneration
MR+2H+—>H2R+M++
Cation
exchanger
Caustic
regenerant
Anion
exchanger
Removal
X-+R(OH)2—»RX+20H-
Regeneration
RX+2OH —> R(OH)2+X'
Deionized effluent
>• Spent regenerant
S-33
NOTES
Chemical Reactions and Separation
7/95
-------
REFERENCES
Superfund University Training Institute. 1990. Hazardous Waste Treatment Technologies Course.
Presented by U.S. Environmental Protection Agency, Office of Research and Development, Risk
Reduction Engineering Laboratory, Cincinnati, OH, and The University of Cincinnati, Cincinnati,
OH, April 24-26, 1990.
U.S. EPA. 1985. Technology Transfer Handbook: Remedial Action at Waste Disposal Sites
(Revised). EPA/625/6-85/006. U.S. Environmental Protection Agency, Office of Research and
Development, Hazardous Waste Engineering Research Laboratory, Cincinnati, OH.
U.S. EPA. 1991. E.I. DuPont De Nemours & Company/Oberlin Filter Company Microfiltration
Technology: Applications Analysis Report. EPA/540/A5-90-007. U.S. Environmental Protection
Agency, Office of Research and Development, Risk Reduction Engineering Laboratory, Cincinnati,
OH.
U.S. EPA. 1994. Superfund Innovative Technology Evaluation: Demonstration Bulletin, Forager
Sponge Technology. EPA/540/MR-94/522. U.S. Environmental Protection Agency, Center for
Environmental Research Information, Cincinnati, OH.
U.S. EPA. 1994. Superfund Innovative Technology Evaluation: Demonstration Bulletin, SFC
Olefiltration System. EPA/540/MR-94/525. U.S. Environmental Protection Agency, Center for
Environmental Research Information, Cincinnati, OH.
U.S. EPA. 1994. Superfund Innovative Technology Evaluation: Emerging Technology Bulletin,
Alternating Current Electrocoagulation. EPA/540/F-92/011. U.S. Environmental Protection
Agency, Center for Environmental Research Information, Cincinnati, OH.
U.S. EPA. 1994. Superfund Innovative Technology Evaluation: Emerging Technology Bulletin,
Volatile Organic Compound Removal from Air Streams by Membranes Separation. EPA/540/F-
94/503. U.S. Environmental Protection Agency, Center for Environmental Research Information,
Cincinnati, OH.
U.S. EPA. 1994. Superfund Innovative Technology Evaluation: Emerging Technology Summary,
Acid Extraction Treatment System for Treatment of Metal Contaminated Soils. EPA/540/SR-94/513.
U.S. Environmental Protection Agency, Center for Environmental Research, Cincinnati, OH.
U.S. EPA. 1994. Superfund Innovative Technology Evaluation: Emerging Technology Summary,
Cross-Flow Pervaporation for Removal of VOCs from Contaminated Wastewater. EPA/540/SR-
94/512. U.S. Environmental Protection Agency, Center for Environmental Research Information,
Cincinnati, OH.
U.S. EPA. 1994. Superfund Innovative Technology Evaluation: Emerging Technology Summary,
Electro-Pure Alternating Current Electrocoagulation. EPA/540/S-93/504. U.S. Environmental
Protection Agency, Center for Environmental Research Information, Cincinnati, OH.
7/95 15 Chemical Reactions and Separation
-------
U.S. EPA. 1994. Superfund Innovative Technology Evaluation: SITE Technology Capsule, Filter
Flow Technology, Inc., Colloid Polishing Filter Method. EPA/540/R-94/501a. Center for
Environmental Research Information, Cincinnati, OH.
U.S. EPA. 1994. Superfund Innovative Technology Evaluation Program: Technology Profiles,
Seventh Edition. EPA/540/R-94/526. U.S. Environmental Protection Agency, Office of Research
and Development, Risk Reduction Engineering Laboratory, Cincinnati, OH.
Chemical Reactions and Separation 16 7/95
-------
Section 11
-------
BIOREMEDIATION FOR
SOILS AND SLUDGES
STUDENT PERFORMANCE OBJECTIVES
At the conclusion of this unit, students will be able to:
1. List five considerations for using bioremediation in soils
2. List three composting treatment systems
3. Describe a land farming treatment system
4. Describe the two stages of the Navajo Vats bioremediation
process
5. Describe a typical slurry system used for bioremediation of
soils
6. List two components found in a typical bioventing system
7. Describe four steps in the flow path through a traditional in-
situ bioremediation system.
NOTE: Unless otherwise stated, the conditions for
performance are using all references and materials
provided in the course, and the standards of
performance are without error.
7/95
-------
/VOTES
BIOREMEDIATION FOR
SOILS AND SLUDGES
8-1
SITE CONSIDERATIONS
• Soil properties
• Physical conditions
• Microbe types
• Nutrients
• Contaminants
SOIL PROPERTIES
Size
Types
Tilth
Moisture
\t
8-2
S-3
7/P5
Bioremediation for Soils and Sludges
-------
NOTES
PHYSICAL CONDITIONS
• Temperature
• PH fr-0
• Salinity < 2
• Redox potential-
S-4
MICROBES
Bacteria
Fungi
Indigenous
Aerobic/anaerobic
s-s
NUTRIENTS
• Fertilizers
• Carbon sources
• Animal manure
s-s
Bioremediation for Soils and Sludges
7/95
-------
NOTES
CONTAMINANTS
Heavy metals
Corrosives
Oxidizers/reducers
Concentrations
EX-SITU SYSTEMS
omposting
Land farming
Two-stage systems
Slurry systems
S-7
s-e
COMPOSTING/LAND FARMING
Composting
- Open windrow
- Static windrow (sfry
- In-vessel
Land farming
S-9
7/95
Bioremediation for Soils and Sludges
-------
NOTES
SLURRY BIODEGRADATION
• Similar to aqueous
• Most organics
• Inorganic cyanides
S-10
SLURRY BIODEGRADATION SYSTEM
Contaminated
soil
Water
Mixer
Bioreactor
— k j
Centrifuge
Clean
soil
S-11
BIOVENTING
r""^
(• In situ/
• Unsaturated zone (\Ja4os
• Soil vapor extraction
S-12
PtuJ2M
Bioremediation for Soils and Sludges
7/95
-------
NOTES
CONSIDERATIONS
Homogeneous soils
Soil gas readings
Soil permeability (ite*<£
Other conditions
3-13
BIOVENTING SYSTEM
S-14
TRADITIONAL IN-SITU SYSTEM
• Unsaturated/saturated zones
• Pumping/soil flushing
• Petroleum and solvents
• Wood-treating wastes
• Chlorinated compounds
S-1S
7/95
Bioremediation for Soils and Sludges
-------
NOTES
TRADITIONAL IN-SITU SYSTEM
s-ie
BIOREMEDIATION FOR SOILS
• Considerations
• Composting/land farming
• Two-stage systems
• Slurry systems
• Bioventing
• Traditional in-situ systems
8-17
Bioremediation for Soils and Sludges
7/95
-------
REFERENCES
U.S. EPA. 1988. Technology Screening Guide for Treatment of CERCLA Soils and Sludges.
EPA/540/2-88/004. U.S. Environmental Protection Agency, Office of Solid Waste and Emergency
Response, Office of Emergency and Remedial Response, Washington, DC.
U.S. EPA. 1990. Slurry Biodegradation. EPA/540/2-90/016. U.S. Environmental Protection
Agency, Office of Emergency and Remedial Response, Office of Research and Development,
Cincinnati, OH.
U.S. EPA. 1991. Guide for Conducting Treatability Studies Under CERCLA: Aerobic
Biodegradation Remedy Screening. Quick Reference Fact Sheet. EPA/540/2-9l/013b. U.S.
Environmental Protection Agency, Office of Emergency and Remedial Response, Washington, DC.
U.S. EPA. 1993a. Bioremediation Using the Land Treatment Concept. EPA/600/R-93/164. U.S.
Environmental Protection Agency, Office of Solid Waste and Emergency Response, Office of
Research and Development, Washington, DC.
U.S. EPA. 19935. Considerations in Deciding to Treat Contaminated Unsaturated Soils In Situ.
EPA/540/S-94/500. U.S. Environmental Protection Agency, Office of Solid Waste and Emergency
Response, Office of Research and Development, Washington, DC.
U.S. EPA. 1993c. Guide for Conducting Treatability Studies Under CERCLA Biodegradation
Remedy Selection. Interim Guidance. EPA/540/R-93/519a. U.S. Environmental Protection
Agency, Office of Solid Waste and Emergency Response, Washington, DC.
U.S. EPA. 1993d. Guide for Conducting Treatability Studies Under CERCLA: Biodegradation
Remedy Selection. Quick Reference Fact Sheet. EPA/540/R-93/519b. U.S. Environmental
Protection Agency, Office of Solid Waste and Emergency Response, Office of Emergency and
Remedial Response, Washington, DC.
U.S. EPA. 1993e. In Situ Bioremediation of Contaminated Unsaturated Subsurface Soils.
EPA/540/S-93/501. U.S. Environmental Protection Agency, Office of Emergency and Remedial
Response, Office of Research and Development, Cincinnati, OH.
U.S. EPA. 1994. In Situ Biodegradation Treatment. EPA/540/S-94/502. U.S. Environmental
Protection Agency, Office of Emergency and Remedial Response, Office of Research and
Development, Cincinnati, OH.
7/95 7 Bioremediation for Soils and Sludges
-------
vvEPA
United States
Environmental Protection
Agency
Office of Emergency and
Remedial Response
Washington, DC 20460
Office of
Research and Development
Cincinnati, OH 45268
Superfund
EPA/540/2-90/016
September 1990
Engineering Bulletin
Slurry Biodegradation
Purpose
Section 121(b) of the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA) mandates
the Environmental Protection Agency (EPA) to select remedies
that "utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the maximum
extent practicable" and to prefer remedial actions in which
treatment "permanently and significantly reduces the volume,
toxicity, or mobility of hazardous substances, pollutants and
contaminants as a principal element." The Engineering Bulletins
are a series of documents that summarize the latest information
available on selected treatment and site remediation
technologies and related issues. They provide summaries of
and references for the latest information to help remedial
project managers, on-scene coordinators, contractors, and
other site cleanup managers understand the type of data and
site characteristics needed to evaluate a technology for potential
applicability to their Superfund or other hazardous waste site.
Those documents that describe individual treatment
technologies focus on remedial investigation scoping needs.
Addenda will be issued periodically to update the original
bulletins.
Abstract
In a slurry biodegradation system, an aqueous slurry is
created by combining soil or sludge with water. This slurry is
then biodegraded aerobically using a self-contained reactor or
in a lined lagoon. Thus, slurry biodegradation can be compared
to an activated sludge process or an aerated lagoon, depending
on the case.
Slurry biodegradation is one of the biodegradation methods
for treating high concentrations (up to 250,00 mg/kg) of
soluble organic contaminants in soils and sludges. There are
two main objectives for using this technology: to destroy the
organic contaminant and, equally important, to reduce the
volume of contaminated material. Slurry biodegradation is not
effective in treating inorganics, including heavy metals. This
technology is in developmental stages but appears to be a
promising technology for cost-effective treatment of hazardous
waste.
Slurry biodegradation can be the sole treatment technology
in a complete cleanup system, or it can be used in conjunction
with other biological, chemical, and physical treatment. This
technology was selected as a component of the remedy for
polychlorinated biphenyl (PCB)-contaminated oils at the General
Motors Superfund site at Massena, New York, [11, p. 2]*but has
not been a preferred alternative in any record of decision [6, p.
6]. It may be demonstrated in the Superfund Innovative
Technology Evaluation (SITE) program. Commercial-scale
units are in operation. Vendors should be contacted to determine
the availability of a unit for a particular site. This bulletin
provides information on the technology applicability, the types
of residuals produced, the latest performance data, site
requirements, the status of the technology, and sources for
further information.
Technology Applicability
Biodegradation is a process that is considered to have
enormous potential to reduce hazardous contaminants in a
cost-effective manner. Biodegradation is not a feasible treatment
method for all sites. Each vendor's process may be capable of
treating only some contaminants. Treatability tests to determine
the biodegradability of the contaminants and the solids/liquid
separation that occurs at the end of the process are very
important.
Slurry biodegradation has been shown to be effective in
treating highly contaminated soils and sludges that have
contaminant concentrations ranging from 2,500 mg/kg to
250,000 mg/kg. It has the potential to treat a wide range of
organic contaminants such as pesticides, fuels, creosote, penta-
chlorophenol (PCP), PCBs, and some halogenated volatile
organics. It is expected to treat coal tars, refinery wastes,
hydrocarbons, wood-preserving wastes, and organic and
chlorinated organic sludges. The presence of heavy metals and
chlorides may inhibit the microbial metabolism and require
pretreatment. Listed Resource Conservation and Recovery Act
(RCRA) wastes it has treated are shown in Table 1 [10, p. 106].
•[Reference number, page number]
"T^ Printed on Recycled Pacer
-------
Table 1
RCRA-Listed Hazardous Wastes
Wood Treating Wastes
Dissolved Air Floatation (OAF) Float
Slop Oil Emulsion Solids
K001
K048
K049
American Petroleum Institute (API) Separator
Sludge K051
The effectiveness of this slurry biodegradation on general
contaminant groups for various matrices is shown in Table
2 [12, p. 13]. Examples of constituents within contaminant
groups are provided in Reference 12, "Technology Screening
Guide for Treatment of CERCLA Soils and Sludges." This table
is based on current available information or professional
judgment when no information was available. The proven
effectiveness of the technology for a particular site or waste
does not ensure that it will be effective at all sites or that the
treatment efficiency achieved will be acceptable at other sites.
For the ratings used for this table, demonstrated biodegradability
means that, at some scale, treatability was tested to show that,
for that particular contaminant and matrix, the technology was
effective. The ratings of potential biodegradability and' no
expected biodegradability are based upon expert judgment.
Where potential biodegradability is indicated, the technology
is believed capable of successfully treating the contaminant
group. When the technology is not applicable or will probably
not work for a particular contaminant group, a no-expected-
biodegradability rating is given. Another source of general
observations and average removal efficiencies for different
treatability groups is contained in the Superfund LOR Guide
#6A, "Obtaining a Soil and Debris Treatability Variance for
Remedial Actions," (OSWER Directive 9347.3-06FS [10], and
Superfund LDR Guide #6B, "Obtaining a Soil and Debris
Treatability Variance for Removal Actions," (OSWER Directive
9347.3-07FS [9].
Limitations
The various characteristics limiting the process feasibility,
the possible reasons for these, and actions to minimize impacts
of these limitations are listed in Table 3 [11, p. 2]. Some of these
actions could be a part of the pretreatment process. The
variation of these characteristics in a particular hardware design,
operation, and/or configuration for a specific site will largely
determine the viability of the technology and cost-effectiveness
of the process as a whole.
Table 2
Degradability Using Slurry Biodegradation
Treatment on General Contaminant Groups for
Soils. Sediments, and Sludges
Contaminant Croups
1
1
"*
£
1
Halogenated volatile*
Halogenated semivolatiles
Nonhalogenated volatile*
Nonhalogenated semivolatiles
PCBs
Pesticides
Oioxins/Furans
Organic cyanides
Organic corrosives
Volatile metals
Nonvolatile metals
Asbestos
Radioactive materials
Inorganic corrosives
Inorganic cyanides
Oxidizers
Reducers
Biodegradability
All Matrices
T
•
T
•
T
•
3
V
a
D
3
3
3
3
T
3
3
• Demonstrated Effectiveness: Successful treatability test at some scale completed
T Potential Effectiveness: Expert opinion that technology will work
2 No Expected Effectiveness: Expert opinion that technology will not work
Technology Description
Figure 1 is a schematic of a slurry biodegradation process.
Waste preparation (1) includes excavation and/or moving
the waste material to the process where it is normally screened
to remove debris and large objects. Particle size reduction,
•.v ater addition, and pH and temperature adjustment are other
important waste preparation steps that may be required to
achieve the optimum inlet feed characteristics for maximum
contaminant reduction. The desired inlet feed characteristics
[6, p. 14] are:
Organics: .025-25%
Solids: 10-40%
Water: 60-90%
Solids particle size:
by weight
by weight
by weight
Less than 1 /4"
Temperature: 15-35'C
pH: 4.5-8.8
Engineering Bulletin: Slurry Biodegradation Treatment
-------
After appropriate pretreatment, the wastes are suspended
in a slurry form and mixed in a tank (2) to maximize the mass
transfer rates and contact between contaminants and
microorganisms capable of degrading those contaminants.
Aerobic treatment in batch mode has been the most common
' mode of operation. This process can be performed in contained
reactors (3) or in lined lagoons [7, p. 9). In the latter case,
synthetic liners have to be placed in existing unlined lagoons,
complicating the operation and maintenance of the system. In
this case, excavation of a new lagoon or above-ground tank
reactors should be considered. Aeration is provided by floating
or submerged aerators or by compressors and spargers. Mixing
is provided by aeration alone or by aeration and mechanical
mixing. Nutrients and neutralizing agents are supplied to
relieve any chemical limitations to microbial activity. Other
materials, such as surfactants, dispersants, and compounds
supporting growth and inducing degradation of contaminant
compounds, can be used to improve the materials' handling
characteristics or increase substrate availability for
degradation [8, p. 5]. Microorganisms may be added initially to
seed the bioreactor or added continuously to maintain the
correct concentration of biomass. The residence time in the
bioreactor varies with the soil or sludge matrix; physical/
chemical nature of the contaminant, including concentration;
and the biodegradability of the contaminants. Once
biodegradation of the contaminants is completed, the treated
slurry is sent to a separation/dewatering system (4). A clarifier
for gravity separation, or any standard dewatering equipment,
can be used to separate the solid phase and the aqueous phase
of the slurry.
Site Requirements
Slurry biodegradation tank reactors are generally
transported by trailer. Therefore, adequate access roads are
required to get the unit to the site. Commercial units require a
setup area of 0.5-1 acre per million gallons of reactor volume.
Standard 440V three-phase electrical service is required.
Compressed air must be available. Water needs at the site can
be high if the waste matrix must be made into slurry form.
Contaminated soils or other waste materials are hazardous and
their handling requires that a site safety plan be developed to
provide for personnel protection and special handling measures.
Climate can influence site requirements by necessitating
covers over tanks to protect against heavy rainfall or cold for
long residence times.
Large quantities of wastewater that results from dewatering
the slurried soil or that is released from a sludge may need to be
stored prior to discharge to allow time for analytical tests to
verify that the standard for the site has been met. A place to
discharge this wastewater must be available.
Onsite analytical equipment for conducting dissolved
oxygen, ammonia, phosphorus, pH, and microbial activity are
needed for process control. High-performance liquid
chromatographic and/or gas chromatographic equipment is
desirable for monitoring organic biodegradation.
Process Residuals
There are three main waste streams generated in the slurry
biodegradation system: the treated solids (sludge or soil), the
process water, and possible air emissions. The solids are
dewatered and may be further treated if they still contain
organic contaminants. If the solids are contaminated with
inorganics and/or heavy metals, they can be stabilized before
disposal. The process water can be treated in an onsite
treatment system prior to discharge, or some of it (as high as 90
percent by weight of solids) is usually recycled to the front end
of the system for slurrying. Air emissions are possible during
operation of the system (e.g., benzene, toluene, xylene [BTX]
compounds); hence, depending on the waste characteristics,
air pollution control, such as activated carbon, may be necessary
[4, p. 29].
Performance Data
Performance results on slurry biodegradation systems are
provided based on the information supplied by various vendors.
The quality assurance for these results has not been evaluated.
In most of the performances, the cleanup criteria were based on
the requirements of the client; therefore, the data do not
necessarily reflect the maximum degree of treatment possible.
Remediation Technologies, Inc.'s (ReTeC) full-scale slurry
biodegradation system (using a lined lagoon) was used to treat
wood preserving sludges (K0001) at a site in Sweetwater,
Tennessee, and met the closure criteria for treatment of these
sludges. The system achieved greater than 99 percent removal
efficiency and over 99 percent reduction in volume attained for
PCP and polynuclear aromatic hydrocarbons (PAHs) (Table 4
and Table 5).
Engineering Bulletin: Slurry Biodegradation Treatment
-------
Figure 1
Slurry Biodegradotion Process
Wa
Prepar
(1
2L. 1 Soil ^
>_|
Water
^
Nutrients/
Additives
Mixing Tank
(2)
Slurry _^
Oxygen
Bio Reactors
(3)
Slurry ^
Dewatering
(4)
^ta
^
Treated
Emissions
_^ Water
Solids
Oversized
Rejects
Table 3
Characteristics Limiting the Slurry Biodegradation Process
CHARACTERISTICS LIMITINC
THE PROCESS FEASIBILITY
Variable waste composition
Nonuniform particle size
Water solubility
Biodegradability
Temperature outside 15-35°C
range
Nutrient deficiency
Oxygen deficiency
Insufficient Mixing
pH outside 4.5 - 8.8 range
Microbial population
Water and air emissions
discharges
Presence of elevated, dissolved
levels of:
• Heavy metals
• Highly chlorinated organics
• Some pesticides, herbicides
• Inorganic salts
REASONS FOR POTENTIAL IMPACT
Inconsistent biodegradation caused by
variation in biological activity
Minimize the contact with microorganisms
Contaminants with low solubility are
harder to biodegrade
Low rate of destruction inhibits process
Less microbial activity outside this range
Lack of adequate nutrients for biological
activity
Lack of oxygen is rate limiting
Inadequate microbes/solids/organics
contact
Inhibition of biological activity
Insufficient population results in low
biodegradation rates
Potential environmental and/or health
impacts
Can be highly toxic to microorganisms
ACTIONS TO MINIMIZE IMPACTS
Dilution of waste stream. Increase mixing
Physical separation
Addition of surfactants or other emulsifiers
Addition of microbial culture capable of
degrading particularly difficult compounds or
longer residence time
Temperature monitoring and adjustments
Nutrient monitoring; adjustment of the
carbon/nitrogen/phosphorus ratio
Oxygen monitoring and adjustments
Optimize mixing characteristics
Sludge pH monitoring. Addition of acidic or
alkaline compounds
Culture test, addition of culture strains
Post-treatment processes (e.g., air scrubbing,
carbon filtration)
Pretreatment processes to reduce the
concentration of toxic compounds in the
constituents in the reactor to nontoxic range
Engineering Bulletin: Slurry Biodegradation Treatment
-------
Table 4
Results Showing Reduction in Concentration for Wood Preserving Wastes
Initital Concentration
Compounds
Phenol
Pentachlorophenol
Naphthalene
Phenanthrene & Anthracene
Fluoranthene
Carbazole
•May be due to combined effect
Solids
(mg/kg)
14.6
687
3,670
30,700
5,470
1,490
Slurry
(mg/kg)
1.4
64
343
2,870
511
139
of Volatilization and Biodegradation.
Final Concentration
Solids
(mg/kg)
0.7
12.3
23
200
67
4.9
Slurry
(mg/kg)
<0.1
0.8
1.6
13.7
4.6
0.3
Percent Removal
Solids
(mg/kg)
95.2*
98.2
99.3*
99.3
98.8
99.7
Slurry
(mg/kg)
92.8
92.8
99.5*
99.5
99.1
99.8
[Source: ReTec, 50,000 gal. reactor]
Table 5
Results Showing Reduction in Volume For Wood Preserving Wastes
Compounds
Phenol
Pentachlorophenol
Naphthalene
Phenanthrene & Anthracene
Fluoranthene
Carbazole
Before Treatment
(Total pounds)
368
141,650
1 79,830
2,018,060
190,440
114,260
•May be due to combined effect of Volatilization and Biodegradation.
After Treatment
(Total pounds)
41.4
193.0
36.6
303.1
341.7
93.7
[Source: ReTec, 50,000 gal. reactor]
Percent Volume
Reduction
88.8*
99.9
99.9*
99.9
99.8
99.9
Data for one of these pilot-scale field demonstrations,
which treated 72,000 gallons of oil refinery sludges, are shown
in Figure 2 [8, p. 24], In this study, the degradation of PAHs was
relatively rapid and varied depending on the nature of the
waste and loading rate. The losses of carcinogenic PAHs
(principally the 5- and 6-ring PAHs) ranged from 30 to 80
percent over 2 months while virtually all of the noncarcinogenic
PAHs were degraded. The total PAH reduction ranged from 70
to 95 percent with a reactor residence time of 60 days.
ECOVA's full-scale, mobile slurry biodegradation unit was
used to treat more than 750 cubic yards of soil contaminated
with 2,4-Dichlorophenoxy acetic acid (2,4-D) and 4-chloro-2-
methyl-phenoxyacetic acid (MCPA) and other pesticides such
as alachlor, trifluralin, and carbofuran. To reduce 2,4-D and
MCPA levels from 800 ppm in soil and 400 ppm in slurry to less
than 20 ppm for both in 13 days, 26,000-gallon bioreactors
capable of handling approximately 60 cubic yards of soil were
used. The residuals of the process were further treated through
land application [3, p. 4]. Field application of the slurry bio-
degradation system designed by ECOVA to treat PCP-
contaminated wastes has resulted in a 99-percent decrease in
PCP concentrations (both in solid and aqueous phase) over a
period of 24 days [3, p. 5].
Performance data for Environmental Remediation, Inc.
(ERI) is available for the treatment of American Petroleum
Institute (API) separator sludge and wood-processing wastes.
Two lagoons containing an olefin sludge from an API separator
were treated. In one lagoon, containing, 4,000 cubic yards of
sludge, a degradation time of 21 days was required to achieve
68 percent volume reduction and 62 percent mass oil and
grease reduction at an operating temperature of 18'C. In the
second lagoon, containing 2,590 cubic yards of sludge, a
treatment time of 61 days was required to achieve 61 percent
sludge reduction and 87.3 percent mass oil and grease reduction
at an operating temperature of 14'C [1, p. 367).
At another site, the total wood-preserving constituents
were reduced to less than 50 ppm. Each batch process was
Engineering Bulletin: Slurry Biodegradation Treatment
-------
Figure 2
Pilot Scale Results on Oil Refinery Sludges
1500 _,
1000 -
I
2
o
500 -
[J Non Care. PAH
• Care. PAH
(Source: ReTeC]
Days:
% Solids:
Sample:
0 60
5%
Lagoon
0 60
10%
Sludge
Pit
Sludge
carried out with a residence time of 28 days in 24-foot-
diameter, 20-foot-height tank reactors handling 40 cubic yards
per batch [6]. The mean concentrations of K001 constituents
before treatment and the corresponding concentrations after
treatment, for both settled solids and supernatant, are provided
in Table 6 [2, p. 11 J. The supernatant was discharged to a local,
publicly owned wastewater treatment works.
RCRA Land Disposal Restrictions (LORs) that require
treatment of wastes to best demonstrated available technology
(BOAT) levels prior to land disposal may sometimes be
determined to be applicable or relevant and appropriate
requirements (ARARs) for CERCLA response actions. Slurry
biodegradation can produce a treated waste that meets
treatment levels set by BOAT, but may not reach these treatment
levels in all cases. The ability to meet required treatment levels
is dependent upon the specific waste constituents and the
waste matrix. In cases where slurry biodegradaton does not
meet these levels, it still may, in certain situations, be selected
for use at the site if a treatability variance establishing alternative
treatment levels is obtained. EPA has made the treatability
variance process available in order to ensure that LORs do not
unnecessarily restrict the use of alternative and innovative
treatment technologies. Treatability variances may be
justified for handling complex soil and debris matrices. The
following guides describe when and how to seek a treatability
variance for soil and debris: Superfund LOR Guide #6A,
"Obtaining a Soil and Debris Treatability Variance for Remedial
Actions," (OSWER Directive 9347.3-06FS) [10] and Superfund
LDR Guide #6B, "Obtaining a Soil and Debris Treatability
Variance for Removal Actions" (OSWER Directive 9347.3-07FS)
[9]. Another approach could be to use other treatment
techniques in series with slurry biodegradation to obtain desired
treatment levels.
Technology Status
Biotrol, Inc. has a pilot-scale slurry bioreactor that consists
of a feed storage tank, a reactor tank, and a dewatering system
for the treated slurry. It was designed to treat the fine-particle
slurry from its soil-washing system. Biotrol's process was
included in the SITE program demonstration of its soil-washing
system at the MacGillis and Gibbs wood-preserving site in New
Brighton, Minnesota, during September and October of 1989.
Performance data from the SITE demonstration are not currently
available; the Demonstration and Applications Analysis Report
is scheduled to be published in latel 990.
Engineering Bulletin: Slurry Biodegradation Treatment
-------
Table 6
Results of Wood Preserving Waste Treatment
Wood Preserving Waste
Constituents
2-Chlorophenol
Phenol
2,4-Dimethylphenol
2,4,6-Trichlorophenol
p-Chloro-m-cresol
Tetrachlorophenol
2,4-Dinitrophenol
Pentachlorophenol
Naphthalene
Acenaphthylene
Phenanthrene + Anthracene
Fluoranthene
Chrysene -f Benz(a)anthracene
Benzo(b)fluoranthene
Benzo(a)pyrene
lndeno(1,2,3-cd)pyrene +
Dibenz(a, h)anthracene
Carbazole
Before treatment
In Soil
(mg/kg)
1.89
3.91
7.73
6.99
118.62
11.07
4.77
420.59
1078.55
998.80
6832.07
1543.06
519.32
519.32
82.96
84.88
135.40
After Treatment
In Settled Soil
(mg/kg)
<0.01
<0.01
<0.01
<0.01
<0.01
<0.02
<0.03
3.1
<0.01
1.4
3.8
4.9
1.4
<0.03
0.1
0.5
<0.05
In Supernatant
(mg/L)
<0.01
<0.01
<0.01
<0.01
<0.01
<0.02
<0.03
<0.01
0.04
1.60
3.00
16.00
8.20
4.50
2.50
1.70
1.70
[Source: Environmental Solutions, Inc.]
ECOVA Corporation has a full-scale mobile slurry
biodegradation system. This system was demonstrated in the
field on soils contaminated with pesticides and PCP. ECOVA
has developed an innovative treatment approach that utilizes
contaminated ground water on site as the make up water to
prepare the slurry for the bioreactor.
ERI has developed a full-scale slurry biodegradation system.
ERI's slurry biodegradation system was used to reduce sludge
volumes and oil and grease content in two wastewater treatment
lagoons at a major refinery outside of Houston, Texas, and to
treat 3,000 cubic yards of wood-preserving waste (creosote-
K001) over a total cleanup time of 18 months.
Environmental Solutions, Inc. reportedly has a full-scale
slurry biodegradation system, with a treatment capacity of up
to 100,000 cubic yards, that has been used to treat petroleum
and hydrocarbon sludges.
Croundwater Technology, Inc. reportedly has a full-scale
slurry biodegradation system, which employs flotation, reactor,
and clarifier/sedimentation tanks in series, that has been used
to treat soils contaminated with heavy oils, PAHs, and light
organics.
ReTeC's full-scale slurry biodegradation system was used
in two major projects: Valdosta, Georgia, and Sweetwater,
Tennessee. Both projects involved closure of RCRA-regulated
surface impoundments containing soils and sludges
contaminated with creosote constituents and PCP. Each project
used in-ground, lined slurry-phase bioreactor cells operating at
100 cubic yards per week. Residues were chemically stabilized
andfurthertreated by tillage. Forfinal closure, the impoundment
areas and slurry-phase cells were capped with clay and a heavy-
duty asphalt paving [5]. ReTeC has also performed several pilot-
scale field demonstrations with their system on oil refinery
sludges (RCRA K048-51).
One vendor estimates the cost of full-scale operation to be
$80 to $150 per cubic yard of soil or sludge, depending on the
initial concentration and treatment volume. The cost to use
slurry biodegradation will vary depending upon the need for
additional pre- and post-treatment and the addition of air
emission control equipment.
EPA Contact
Technology-specific questions
degradation may be directed to:
regarding slurry bio-
Dr. Ronald Lewis
U.S. EPA Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Cincinnati, Ohio 45268
Telephone: FTS 684-7856 or (51 3) 569-7856.
Engineering Bulletin: Slurry Biodegradation Treatment
.S. GOVERNMENT PRINTING OrFICE: till •
-------
REFERENCES
1. Christiansen,)., T. Koenig, and C. Lucas. Topic 3:
Liquid/Solids Contact Case Study. In: Proceedings
from the Superfund Conference, Environmental
Remediation, Inc., Washington, D.C., 1989. pp. 365-
374.
2. Christiansen, |., B. Irwin, E. Titcomb, and S. Morris.
Protocol Development For The Biological Remediation
of A Wood-Treating Site. In: Proceedings from the 1 st
International Conference on Physicochemical and
Biological Detoxification and Biological Detoxification
of Hazardous Wastes, Atlantic City, New Jersey, 1989.
3. ECOVA Corporation. Company Project Description,
(no date).
4. Kabrick, R., D. Sherman, M. Coover, and R. Loehr.
September 1989, Biological Treatment of Petroleum
Refinery Sludges. Presented at the Third International
Conference on New Frontiers for Hazardous Waste
Management, Remediation Technologies, Inc.,
Pittsburgh, Pennsylvania, 1989.
5. ReTeC Corporation. Closure of Creosote and
Pentachlorophenol Impoundments. Company
Literature, (no date).
6. Richards, D. |. Remedy Selection at Superfund Sites on
Analysis of Bioremediation, 1989 AAAS/EPA
Environmental Science and Engineering Fellow, 1989.
7. Stroo, H. F., Remediation Technologies Inc. Biological
Treatment of Petroleum Sludges in Liquid/Solid
Contact Reactors. Environmental and Waste
Management World 3 (9): 9-12, 1989.
8. Stroo, H.F., |. Smith, M. Torpy, M. Coover, and R.
Kabrick. Bioremediation of Hydrocarbon-
Contaminated/Solids Using Liquid/Solids Contact
Reactors, Company Report, Remediation Technologies,
Inc., (no date), 27 pp.
9. Superfund LDR Guide #6B: Obtaining ; Soil and Debris
Treatability Variance for Removal Actions. OSWER
Directive 9347.3-07FS, U.S. Environmental Protection
Agency, 1989.
10. Superfund LDR Guide #6A: Obtaining a Soil and
Debris Treatability Variance for Remedial Actions.
OSWER Directive 9347.3-06FS, U.S. Environmental
Protection Agency, 1989.
11. Innovative Technology: Slurry-Phase Biodegradation.
OSWER Directive 9200.5-2S2FS, U.S. Environmental
Protection Agency, 1989.
12. Technology Screening Guide for Treatment of CERCLA
Soils and Sludges. EPA/540/2-88/004, U.S.
Environmental Protection Agency, 1988.
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati, OH 45268
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use $300
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United States
Environmental Prelection
Agency
O!'ica of Research 3--c
Development
Washington. DC 2--6C
E?i 500-R-92
A'jcust 1992
Bioremediation Using the
Land Treatment Concept
\
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EPA/600/R-93/164
Environmental Regulations
and Technology
Bioremediation Using the
Land Treatment Concept
Daniel F. Pope and John E. Matthews
August 1993
This report was developed by the
Robert S. Kerr Environmental Research Laboratory
U.S. EPA, ORD
Ada, Oklahoma 74820
Printed on Recycled Paper
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DISCLAIMER
The information in this document has been funded in part by the United States Environmental Protection Agency under
Contract No. 68-C8-005S to Oynamac Corporation. It has been subjected to the Agency's peer and administrative review, and
it has been approved for publication as an EPA document Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.
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FOREWORD
EPA is charged by Congress to protect the nation's land, air and water systems. Under a mandate of national environmental
laws focused on air and water quality, solid waste management and the control of toxic substances, pesticides, noise and
radiation, the Agency strives to formulate and implement actions which lead to a compatible balance between human activities
and the ability of natural systems to support and nurture life.
The Robert S. Kerr Environmental Research Laboratory is the Agency's center of expertise for investigation of the soil and
subsurface environment. Personnel at the Laboratory are responsible for management of research programs to: (a)
determine the fate, transport and transformation rates of pollutants in the soil, the unsaturated and saturated zones of the
subsurface environment; (b) define the processes to be used in characterizing the soil and subsurface environment as a
receptor of pollutants; (c) develop techniques for predicting the effect of pollutants on ground water, soil, and indigenous
organisms; and (d) define and demonstrate the applicability and limitations of using natural processes, indigenous to the soil
and subsurface environment, for the protection of this resource.
Bioremediation processes using the land treatment concept, whereby contaminated soil is treated in place or excavated and
treated in prepared-bed treatment units, are common soil remediation technologies proposed for hazardous waste sites.
However, RSKERL and other research and demonstration studies have identified complex biological, chemical and physical
interactions within contaminated subsurface media which may impose limitations on the overall effectiveness of bioremediation
processes utilizing the land treatment concept This report was developed to summarize and discuss basic considerations
necessary to implement and manage these types of bioremediation systems to improve their efficiency and effectiveness in
reclaiming contaminated soils.
Clinton W. Hall
Director
Robert S. Kerr Environmental Research Laboratory
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CONTENTS
INTRODUCTION 1
Definition of Land Treatment 1
Microorganisms and Bioremediation 1
LAND TREATMENT TECHNOLOGY 3
In-Situand Ex-Situ Land Treatment 3
Lift Application and Tilling 3
Nutrients, Carbon Sources, and Other Additives 4
Bioaugmentation 5
Soil Moisture Control 5
Types and Concentrations of Contaminants Remediable by Land Treatment 6
Petroleum Derived Contaminants 6
Wood Preserving Contaminants : 7
Levels of Contamination Susceptible to Land Treatment 7
BIBLIOGRAPHY 8
Land Treatment Concept References 8
Soil Properties References 8
Monitoring References 8
Petroleum Contaminant References 9
Wood Preserving Contaminant References 9
APPENDIX A-
SOIL PROPERTIES 10
Soil Horizons 10
Depth 10
Texture 10
Bulk Density 10
Porosity, Hydraulic Conductivity, and Permeability 10
Soil Moisture and Water Holding Capacity 11
Tilth 12
Sorptive and Exchange Capacity 12
Organic Matter 12
pH 12
Nutrients 12
Salinity 13
Redox Potential 13
Color 13
Biological Activity 13
Metaisin Soils 13
APPENDIX B-
MONITORING 14
Waste Transformation 14
Parent Compound Loss 14
Breakdown Products 14
Toxicity Reduction 14
Microorganisms 15
Soil Moisture 15
Nutrients 15
SAMPLING STRATEGIES 15
Measuring Transformation Rates 16
Volatilization. Leachate and Runoff 17
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INTRODUCTION
land treatment concept serves as the basis for design and
operation of soil bioremediation technologies at a large
number of waste sites requiring cleanup.
This document is designed to be used by those who are
involved with the use of land treatment technologies for the
remediation of contaminated solid phase materials. In
addition to a discussion of the basic processes which drive
land treatment applications, the parameters involved in these
processes are examined with respect to the efficiency as
well as the failure of such systems. Design and operation
criteria are suggested in areas ranging from pH control to
tilling practices and moisture and nutrient requirements.
Contaminants commonly related to the wood preserving and
petroleum industries are addressed with respect to their
applicability to land treatment in terms of treatability, loading
rates, and cleanup levels. A bibliography containing
references for further information is provided along with
appendices covering soil properties important in land
treatment and a discussion of monitoring procedures.
Bioremediation of contaminated soils using the land
treatment concept is currently under consideration for
implementation at a large number of Superfund, UST, and
RCRA sites. The ultimate success of these remediations will
depend on systematic design and operation of each specific
land treatment unit. This document is designed to be used
by those who have responsibility for design and day-to-day
operation of a land treatment facility, or who are responsible
for overseeing design and operation of the facility. The
document provides a short discussion of fundamental
processes involved in land treatment, design and operation
of the land treatment unit (LTD), and a bibliography
containing references for further study. Also included are
appendices covering soil properties important in land
treatment and a short discussion of monitoring procedures.
Definition of Land Treatment
Land treatment involves use of natural biological, chemical
and physical processes in the soil to transform organic
contaminants of concern. Biological activity apparently
accounts for most of the transformation of organic
contaminants in soil, although physical and chemical
mechanisms may provide significant loss pathways for some
compounds under some conditions. Degradation by
ultraviolet light may serve as a loss pathway for certain
hydrophobia compounds at the soil surface. Volatilization of
low molecular weight compounds also takes place at the soil
surface and provides a significant loss pathway for such
compounds. Certain chemical reactions such as hydrolysis
can play an important role in transformation of some
compounds. Humification, the addition of compounds to the
humic materials in soil, can be important routes of
transformation for some polycyclic aromatic compounds.
The relative importance of these processes varies widely for
different compounds under different circumstances. The
Microorganisms and Bioremediation
Bioremediation is carried out by microorganisms. Both
bacteria and fungi have been shown to be important in
bioremediation processes. Most research in bioremediation
has centered on bacteria, but some investigators have found
that fungi can play an important role in bioremediation
processes, especially with halogenated compounds (e.g.,
pentachlorophenol, a wood preservative). It is important to
realize, however, that in almost all cases bioremediation
relies on communities of microorganism species, rather than
one or a few species.
Bioremediation consists of utilizing techniques for enhancing
development of large populations of microorganisms that
can transform the pollutants of interest, and bringing these
microorganisms into intimate contact with the pollutants. In
order to do this efficiently, necessary provisions for microbial
growth and reproduction must be maintained.
Life processes for all known living creatures are carried out
in water. Some organisms, such as human beings, can
maintain an internal water environment while moving about
in a relatively dry outer environment. Many microorganisms,
however, cannot maintain an appropriate inner environment
without being in a relatively wet outer environment. Most
microorganisms that are active in bioremediation must live in
water. This water may be in tank reactors or an aquifer, or it
may be a thin film of water on a soil particle or oil droplet.
Microorganisms are sensitive to the osmotic potential of the
solution in which they function. The osmotic potential affects
the ability of the microorganism to maintain itself with a
desirable amount of water internally. If the environment is
too dry, or if the water in the microorganism's environment
contains excessive concentrations of solutes, the
microorganism cannot maintain the proper amount of water
internally. This factor can be a problem for bioremediation
schemes where, for example, process waters or
contaminated soils have high levels of dissolved salts.
Sudden changes in osmotic potential can inhibit microbial
activity, often resulting in lysis (disintegration of cell walls).
Microorganisms can adapt to environmental changes within
limits if such changes are not induced rapidly.
Specific microorganisms are active within a relatively narrow
range of temperatures. Most bacteria that carry out
bioremediation processes are mesophiles ("middle lovers")
and are most active from about 18 to 30 degrees centigrade.
Significantly higher or lower temperatures will limit their
activity. Within this range, activity will usually be greater at
the higher temperatures. Activity decreases as the
temperature moves further outside these limits. At lower
temperatures, activity does not usually stop completely until
the freezing point is reached.
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Most microorganisms active in bioremediation
processes are aerobic, that is, they require free
(uncombined) oxygen. Some treatment processes
make use of anaerobic microorganisms that do not
require free oxygen; however, these processes are not
yet widely used in environmental cleanups.
Microorganisms living in aqueous reactors, aquifers, or
in the subsoil may be supplied with oxygen by pumping
air or oxygen-supplying compounds (e.g., hydrogen
peroxide) into the environmental system.
Microorganisms growing in surface soil are usually
supplied with oxygen by tilling the soil to facilitate air
entry. In many remediation situations the essential
problem is the balance between water and oxygen: the
more water, the less oxygen, and vice versa. In the soil
environment, the oxygen supply and the water supply to
microorganisms are essentially inversely related, since
the pore space in soil is occupied by either air or water.
Microorganisms are active within a relatively broad pH
range. The pH is a measure of the acidity or basicity of
the environment. However, many microorganisms are
inhibited below pH 5 or above pH 9. Although many
microorganisms can adapt to pH levels within that
range, it is thought that fungal species tend to be the
more active members of the microorganism community
below pH 6, and bacteria tend to dominate above pH 7.
The pH range within which bioremediation processes
are considered to operate most efficiently is 6 to 8. The
optimum pH range for a particular situation, however, is
influenced by a complex relationship between the
microorganisms, pollutant chemistry and external
environment, and thus is site-specific. The pH can be
adjusted to the desired range by the addition of acidic
or basic substances (i.e., sulphur or lime).
Microorganisms are sensitive to the presence of a wide
variety of compounds and elements. High
concentrations of heavy metals, certain highly
halogenated organics, some pesticides and other
exogenous materials can inhibit bioremediation. Effects
of these inhibitors vary with concentration,
environmental factors, rapidity of contact with the
inhibitors, and time of contact such that it is difficult to
set any definite concentration limits above which
bioremediation is precluded. Laboratory treatability
studies often can be used to provide data necessary for
management decisions regarding the impact of a given
inhibitor at field scale.
Metals often are present in soils contaminated with
organic wastes. These metals will not be treated
(transformed or degraded) in the same sense as the
organic materials. However, valence states may be
changed and chemical bonds may be broken so as to
change the toxicity or mobility of the metals. Addition of
manures and other complex organic materials often
used in land treatment may reduce the mobility of many
metals by increasing the ion exchange capacity or
adsorption capacity of the soil.
Microorganisms must have carbon sources and mineral nutrients
(nitrogen and phosphorus, for example) in order to live and
reproduce. In many cases, the pollutants themselves will supply
the carbon source and some nutrients; however, mineral nutrients
and a supplemental carbon source may be supplied if needed.
Mineral nutrients are usually supplied as soluble salts (fertilizers).
If necessary, carbon may be supplied as animal manures (which
will also supply many mineral nutrients), molasses, glucose, wood
chips, com cobs or a variety of other carbon containing materials.
There must be a balance between the various mineral nutrients
and the carbon source or the microorganisms will not be able to
make optimum use of the carbon source. For most bioremedi-
ation situations, it is supposed that biodegradation is optimal at
carbon/nitrogen ratios in the range of 10-30 to 1, and nitrogen/
phosphorus ratios of about 10 to 1 by weight Research and field
experience indicates that these ratios may vary widely depending
on the type of carbonaceous materials present
There are 15 or more other mineral nutrients that must be
available in appropriate amounts. With the exception of some
process waters and ground waters, these minor nutrients are
usually present in the environment in sufficient amounts. The
amounts of foods and nutrients to be added should be based on
results from laboratory and site treatability studies.
The availability of nutrients to microorganisms is strongly
influenced by pH since soil pH generally is maintained or adjusted
to the 5-8 pH range in a land treatment scenario. Limited
availability of nutrients caused by pH is rarely a problem.
Since microorganisms are responsible for transformation of
pollutants during bioremediation, it would seem reasonable to
assume that the greater the number of microorganisms present,
the faster the transformation would occur. However, results of
population counts and analyses for parent compound
disappearance or transformation are often not closely correlated.
Instead, the rate of transformation is more closely correlated to
the rate at which oxygen and electron acceptor can be
transported to the system.
Several techniques have been devised to determine the
microorganism population. One commonly used method is
standard plate counting. Samples of soil, water, or other matrices
in which microorganisms are growing are applied to Petri plates
containing a nutrient media. The plates are incubated for several
days to allow microorganisms to grow, after which the number of
microorganism colonies growing on the plates are counted. These
counts can then be related to the numbers of microorganisms
present in the original matrix; however, the relationship between
population counts and pollutant transformation rates is not well
defined. Often, there are many types of microorganisms in the
bioremediation environment that will be counted in plate counts,
but only a few of these types may actually be involved in
transformation of the contaminants of concern. The nutrient
media may be spiked with waste compounds of interest;
microorganisms that grow on such media are considered to be
tolerant to the spiked compounds. The use of spiked media
yields an indication of population levels of tolerant micro-
organisms in the soil tested. Note that this procedure does not
give an indication of the microorganisms present that can degrade
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the spiked compound, only those that can survive and grow
in the presence of the spiked levels of the compounds.
There are several physical constraints on the use of
microorganisms in remediation of soil contaminants. These
are generally related to the problem of getting contaminants
and microorganisms in close contact under environmental
conditions conducive to microbial activity. Generally, a
contaminant must be able to move through the waste/soil
matrix and pass through the microorganism's cell membrane
in order for transformation to occur. In some cases
contaminants can be transformed by extracellular enzymes
(cooxidation or cometabolism) without entering into the
microorganisms.
Waste compounds that have low solubilities in water (for
example, 4, 5, and 6 ring polycyclic aromatic hydrocarbons
[PAHs]) move slowly from soil adsorption sites or free phase
droplets into the soil water and from there into the
microorganism. Wastes in solid matrices (soil) will have less
solvent (water) in which to be dissolved, will be more likely to
have highly variable concentrations throughout the matrix,
will be harder to mix thoroughly for even distribution
throughout the matrix, and often will have a relatively high
tendency to be adsorbed onto matrix solids.
All of these factors tend to limit accessibility of contaminant
compounds to the microorganisms; therefore it is often
easier to achieve biodegradation of a given contaminant in
water than in soil. Also, soil treatment processes where soil
is suspended in water and constantly mixed (soil slurry
bioremediation) will usually have faster biotransformation
rates than simple solid phase soil bioremediation processes.
LAND TREATMENT
TECHNOLOGY
In-Situ and Ex-Situ Land Treatment
Land treatment techniques for bioremediation purposes most
often are used for treatment of contaminated soil, but certain
petroleum waste sludges have long been applied to soil for
treatment. Ideally, the contaminated soil can be treated in
place (in-situ). Often, however, the soil must be excavated
and moved to a location better suited to control of the land
treatment process (ex-situ).
In-situ land treatment is limited by the depth of soil that can
be effectively treated. In most soils, effective oxygen
diffusion sufficient for desirable rates of bioremediation
extends to a range of only a few inches to about 12 inches
into the soil. Usually when it is desired to treat soil in-situ to
depths greater than 12 inches, the surface layer of soil is first
treated to the desired contaminant levels, and then removed,
or tilled so that lower layers are moved to the surface for
treatment. Most tractor mounted tilling devices can till only
to a depth of about 12 inches. Large tractors with
specialized equipment that can till to depths of 3 feet or
more have been used for in-situ land treatment. Large
augers are now available that can move soil from 50-100
feet depths to the surface, but the practicality of this
technique for in-situ land treatment has not been
demonstrated.
Ex-situ treatment generally involves applications of lifts of
contaminated soil to a prepared bed reactor. This reactor is
usually lined with clay and/or plastic liners, provided with
irrigation, drainage and soil water monitoring systems, and
surrounded with a berm. The lifts of contaminated soil are
usually placed on a bed of relatively porous non-
contaminated soil.
Whether practiced in-situ or ex-situ, effective land treatment
is generally limited to the top 6 to 24 inches of soil, with 12
inches or less being the preferred working depth. At depths
below 12 inches, the oxygen supply is generally inadequate
for useful rates of bioremediation using standard land
treatment practices. Tilling is used to mix the soil and
increase the oxygen levels, but is usually limited to 12 inches
or less unless specialized equipment is available.
The land treatment process may be severely limited in
clayey soils, especially in areas of high rainfall. This
limitation is primarily related to oxygen transfer limitations
and substrate availability to the microorganisms. Clayey
soils should be applied in shallower lifts than sandy soils,
preferably no more than 9 inches in depth. Tilth
("workability" of the soil) can often be improved by adding
organic matter or other bulking agents to the soil. If high
sodium content causes the soil to have poor tilth, gypsum
(calcium sulfate) can be added.
The soil should be screened before application to remove
any debris greater than one inch in diameter, especially if
significant amounts of debris or rocks are present. Any large
debris that may adsorb the waste compounds (i.e., wood),
should be removed if possible and treated separately. Small
rocks and other relatively nonadsorptive wastes can be
treated if they do not interfere with tillage operations.
Lift Application and Tilling
After application to the land treatment unit, each lift should
be tilled at intervals to enhance oxygen infiltration and
contaminant mixing with the microorganisms. The soil
should be near the lower end of the recommended soil
moisture percentage range before tilling. Tilling very wet
or saturated soil tends to destroy the soil structure, reduce
oxygen and water intake, and cause reduced microbial
activity. Tilling should not begin until at least 24 hours
after irrigation or a significant rainfall event. Tilling more
than is necessary for enhanced oxygen infiltration and
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contaminant mixing may be counter-productive since it
tends to destroy the soil structure and compact soil below
the tilling zone. Tillers tend to mix soil only along the
tractor's line of travel, so tillage should be carried out in
varying directions, i.e., lengthwise of the LTD, crosswise,
and on the diagonal.
A tractor mounted rotary tiller is recommended. Occasion-
ally a subsoil plow or chisel plow should be used to break up
any hardpan or zone of compaction created by passage of
equipment across the LTD. If the tiller does not operate
deeply enough to mix soil from the last lift into the top few
inches of soil from the preceding lift, a turning plow may be
used to achieve desired mixing of the two lifts. Use of the
turning plow should be followed immediately by tilling to
complete the mixing action.
Each subsequent lift, usually 6-12 inches in depth, should be
tilled into the top two or three inches of the previous lift. This
will mix populations of well acclimated microorganisms from
the treated lift into the newly applied lift, and help reduce the
length of time for high populations of active degraders to be
built up in the new lift.
Timing of application of succeeding lifts should be based on
reduction to defined levels of particular compounds or
categories of compounds in the preceding lift. For instance,
the goal might be to reduce total petroleum hydrocarbons
(TPH) to less than a regulatory or risk calculated limit in the
current lift before application of a new lift.
Once desired target levels of compounds of interest are
established, data obtained from the LTD monitoring activities
can be statistically analyzed to determine if and when
desired levels are reached and the LTD is ready for
application of another lift
Nutrients, Carbon Sources, and Other
Additives
Microorganisms in land treatment units require carbon
sources and nutrients. Fertilizers can be used to supply the
nutrients, while wood chips, sawdust or straw can supply
carbon. Various animal manures are often used to supply
both carbon sources and nutrients. High organic levels in
manures, wood chips and the other organic amendments
increase sorptive properties of soil, thereby decreasing
mobility of organic contaminants.
Organic amendments will also increase the water holding
capacity of soil, which can be desirable in sandy soils, but
can cause difficulty when land treatment is conducted in
areas of high rainfall and poor drainage. In an excessively
wet soil the oxygen supply is reduced, which may essentially
stop or severely limit transformation of waste constituents.
Drainage must be carefully designed and managed in these
situations.
Animal manures can provide desirable organic supplements.
Manure should be applied to each lift at the rate of about
3% - 4% by weight of soil. The manure should be analyzed
for nitrogen and phosphorus to determine if any additional
amounts of these nutrients need be applied. The manure
should be in small particles and should be thoroughly tilled
into the soil lift. Initial contaminant levels should be
measured after incorporation of organic supplements to
avoid incorporating dilution effects into calculation of waste
transformation.
Manures are often mixed with sawdust or straw since
these materials are used as bedding in stock facilities.
This is acceptable and even desirable since they act as
bulking agents in soil. However, the high percentage of
cellulosic material will usually exert a high nitrogen
demand, thereby reducing the amount of nitrogen available
to microorganisms for transforming contaminants of
concern. If necessary, available nitrogen can be increased
with addition of appropriate inorganic fertilizers, including
fertilizer grade ammonium nitrate (for nitrogen), triple
superphosphate (for phosphorus), or diammonium
phosphate (for both nitrogen and phosphorus). Nitrogen
fertilizers can cause soil pH to be lowered due to formation
and leaching of the nitrate ion coupled with soil cations.
Agricultural fertilizer is usually supplied in prilled or pelleted
form (the fertilizer compounds formed into pellets with a clay
binder) suitable for easy application over large areas.
Technical grade, unformulated fertilizer compounds (for
instance, ammonium chloride crystals) are difficult to spread
evenly over the land surface. The pelleted fertilizers may be
applied with a hand-operated or tractor-operated cyclone
spreader. Completely water-soluble fertilizers can be
applied through irrigation systems, allowing application rates
to be closely controlled, applications to be made as often as
irrigation water is applied, and immediate availability to the
microorganisms. Equipment is available to meter
concentrated nutrient solutions into the irrigation system on a
demand basis.
Nutrient requirements for biodegradation in the field have not
been thoroughly studied, and detailed information is not
available to indicate the optimal levels of particular
nutrients. The amount of nitrogen and phosphorus needed
may be estimated by having representative soil samples
analyzed by the state agriculture department or university
laboratory, or by a private agricultural soil testing
laboratory. General fertilizer recommendations for
vegetable gardens should be followed. The analytical
laboratory should be made aware that the soil contains
hazardous materials.
Sometimes inorganic micronutrients, microbial carbon
sources, or complex growth factors may be needed to
enhance microbial activity. Animal manures generally will
supply these factors. Proprietary mixtures of these
ingredients are sometimes offered for sale to enhance
microbial activity. Proof of the efficacy/cost effectiveness of
these mixtures is lacking in most cases.
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Bioaugmentation
Microorganism cultures are often proposed for addition to
bioremediation units. Two factors limit use of these added
microbial cultures in LTUs: (1) nonindigenous
microorganisms rarely compete well enough with indigenous
populations to develop and sustain useful population levels,
and (2) most soils with long-term exposure to biodegradable
wastes have indigenous microorganisms that are effective
degraders if the LTU is managed properly. If the use of
proprietary additives is proposed, results of well-designed
treatability studies with appropriate controls should be
provided by the vendor to support such use.
Certain soil factors may interfere with microbiological activity
in the LTU soil. High salt levels, indicated by high electrical
conductivity (EC) readings, may reduce or stop useful
microbiological activity. If levels are too high, it may be
necessary to leach the soil with water to remove excess
salts before biodegradation can occur. High levels of
sodium may be detrimental to soil structure. Sodium levels
may be reduced by applying calcium supplements (usually
gypsum, CaSOj and leaching. Leaching of contaminants
may also occur at the same time.
Soil Moisture Control
Historically, it has been recommended that soil moisture be
maintained in the range of 40% - 70% of field capacity;
however, recent experience indicates that 70% - 80% of field
capacity may be optimum. A soil is at field capacity when
soil micropores are filled with water and soil macropores are
filled with air. This condition allows soil microorganisms to
get air and water, both of which are necessary for aerobic
biodegradation to occur. Maintaining soil at somewhat less
than 100% of field capacity allows more rapid movement of
air into the soil, thus facilitating aerobic metabolism without
seriously reducing the supply of water to microorganisms. If
soils are allowed to dry excessively, microbial activity can be
inhibited or stopped; if the wilting point is reached, cells may
lyse or rupture.
Field capacity of a soil may be determined by saturating a
soil sample with water and allowing it to drain freely for 24
hours. The soil is weighed, oven-dried at 105° C to constant
weight, then weighed again. The difference between the
weight of drained soil and the oven-dried soil gives the
weight of water in that amount of soil at field capacity. The
weight of water divided by the dry weight of the soil gives the
percentage of water in the soil at field capacity. A sandy soil
might hold as little as 5% of its dry weight in water at field
capacity as compared to 30% for a clay soil.
Continuous maintenance of soil moisture at adequate levels
is of utmost importance. Either too little or too much soil
moisture is deleterious to microbial activity. Monitoring soil
moisture and scheduling irrigation is important, requires
constant attention, and is perhaps one of the most neglected
areas of LTU operations.
Moisture enhancement can be accomplished by using
traveling gun or similar irrigation systems that can be
removed to allow easy application of lifts. Hand-moved
sprinkler irrigation systems are more often used, although
they are usually more expensive. Sprinkler systems can be
designed with quick detach couplings to facilitate movement
when placing lifts of contaminated soil. Permanently
installed sprinkler systems with buried laterals and mains
may be used, but the sprinkler uprights must be avoided
when placing soil lifts and during other LTU operations. The
uprights may need to be lengthened if many lifts are placed
during the operating life of the LTU.
If a permanently installed, buried line system is used, the
uprights should be connected to the buried lateral lines with
a short piece of plastic pipe. Some of the uprights will be hit
by field equipment during operations, and the plastic pipe will
break before the lateral line or other parts of the piping
system. The plastic pipe can be easily repaired, while a bent
or broken lateral line or upright can be difficult to repair.
The operating pressure for most sprinklers ranges from 30 to
50 Ib/in2. Sprinklers may have two nozzles, one to apply
water at a distance from the sprinkler (range nozzle) and one
to cover the area near the sprinkler (spreader nozzle).
Sprinklers may be static or rotating, with a hammer or other
device to cause the sprinkler to rotate. Since one sprinkler
will not apply water uniformly over an area, sprinkler patterns
should be overlapped to provide more uniform coverage.
The usual overlap is around 50%; that is, the area covered
by one sprinkler reaches to the next sprinkler. Highly
uniform coverage is difficult to achieve in the field, especially
in areas where winds of more than 5 mph are common.
Small LTUs can be covered with sprinklers set only on the
sides of the LTU. Sprinklers can cover full, half or quarter
circles so that sprinklers on the sides or in the corners of the
LTU will cover only the LTU and not the berm or areas
outside the LTU.
The irrigation system should be sized to allow application of
at least one inch of water in 10-12 hours. The rate of water
application should never be more than the soil can absorb
with little or no runoff since LTUs consist of bare soil and
excessive runoff can rapidly cause significant erosion.
Generally, coarser (sandy or loamy) soils can take up water
at a faster rate than finer textured clay or clay loam soils.
Usually, application rates of more than 0.5 inches of water
per hour are not recommended; clayey soils with slopes
greater than 0.2% - 0.3% will require lower rates of water
application. A water meter to measure the volume of water
applied is helpful in controlling application.
Surface drainage of the LTU can be critical in high rainfall
areas. If soil is saturated more than an hour or two, aerobic
microbial action is reduced. The LTU surface should be
sloped no more than 0.5% -1.0%, as greater slopes will
allow large amounts of soil to be washed into the drainage
system during heavy rains. Even a slope of 0.5% -1.0% will
allow soil to be eroded; therefore the drainage system
should be designed to allow collection and return of eroded
soil to the treatment unit.
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Underdrainage is generally provided by a sand layer or a
geotextile/drainage net layer under the LIU. The system
should be designed so that excess water in soil pores over
field capacity will be quickly drained away so microbial
activity will not be inhibited. The lifts of contaminated soil
are usually placed on a bed of sand or other porous soil,
which results in a "perched" water table. In this event the
contaminated soil lift will take up water from irrigation or rain
until the soil nears saturation, at which point excess water
will be discharged into the treatment unit drainage system.
The interface between the lift and the coarse layer
underneath should be composed of well graded materials so
that the transition from the (usually) relatively fine soil texture
of the lift to the coarse texture of the drainage layer is
gradual rather than sudden. Grading of the materials
reduces the tendency for the soil lift to become saturated
before drainage occurs, which inhibits aerobic biological
activity. The change in texture at the interface can be made
more gradual by tilling the lift into the top few inches of the
drainage layer.
Some storage capacity should be provided so that runoff and
leachate water can be recycled onto the LTD. A one-inch
rain might give a combined runoff and leachate of 10,000 to
27,000 gallons per acre if the LTD is being maintained at the
proper (relatively high) moisture content. Therefore, it may
not be practical to provide storage capacity for large rainfall/
runoff events.
In many cases leachate/runoff water cannot be discharged
without treatment. Biological reactors are commonly used to
treat this water prior to discharge. Alternatively, effluent from
the biological treatment unit may be applied to the LTU
through the irrigation system. Nutrients and microorganisms
from the biological treatment system may enhance the
microbial activity within the LTU.
Types and Concentrations of
Contaminants Remediable by Land
Treatment
The types of contaminants most commonly treated in land
treatment units are petroleum compounds and organic wood
preservatives. Historically, petroleum refineries have used
land treatment to dispose of waste sludges. Although waste
petroleum sludges currently are not often applied to soil for
treatment, the technology has been applied to remediation of
soil contaminated with many types of petroleum products,
including fuel, lubricating oil and used petroleum products.
Land treatment has historically been used to remediate
contaminated process waters from wood preserving
operations. This technology currently is not used for this
purpose, but is currently used to remediate soil
contaminated with wood preserving wastes.
Other applications for land treatment technology include
remediation of soil contaminated with coal tar wastes,
pesticides and explosives. Since coal tar wastes are similar
to creosote wastes (wood preserving creosote is made from
coal tar), such wastes are considered amenable to land
treatment. Land treatment appears to be potentially useful
for certain pesticides, but the evidence for applicability of this
technology to explosives contaminated soil is inconclusive.
Petroleum Derived Contaminants
Crude oil is refined into petroleum products including the
following general groups: gasolines, middle distillates (diesel
fuel, kerosene, jet fuel, lighter petroleum oils), heavier fuel
oils and lubricating oils, and asphalts and tars. Certain
individual compounds may also be produced from crude oil,
including benzene, toluene, hexane, and many others.
Gasoline, a mixture of C4 to C12 hydrocarbons, includes
paraffins (CNH2N>2), olefins (alkenes), naphthenes (5 and 6
carbon cycloparaffms and their alkyl derivatives, sometimes
including polycyclic members), and aromatics (12% to 20%
by weight of gasoline). Jet fuel includes avgas (for propeller-
driven aircraft — similar to gasoline), Jet A & A1 fuel
(commercial aircraft fuel, with a heavy kerosene base), JP4
(Air Force jet fuel, naphtha based), and JP5 (Army jet fuel-
kerosene base). Diesel and kerosene are similar in
composition, being largely composed of chains of 9-17
carbons in length. Heating oil and bunker C are heavy fuel
oils. Lubricating oils contain long chain hydrocarbons (20+ C
chain length). Tars and asphalts are mixtures of long chain,
high molecular weight hydrocarbons including bitumens,
waxes, resins and pitch.
Specific compounds found in petroleum products and
refinery wastes include: aliphatics, olefins, naphthenes, and
asphaltenes; single ring aromatics benzene, toluene, ethyl
benzene and o.m.p-xylene; multiple ring aromatics
(polycyclic aromatic hydrocarbons—PAHs), phenols and
cresols; bitumens, waxes, resins and pitch; and metals
including lead, chromium and cadmium. Caustics (alkali
metal hydroxides) may also be found.
Refinery waste sources include production wastes (refinery
effluents, slop oil-emulsion solids, leaded tank bottoms, heat
exchanger bundle cleaning sludge); incidental wastes
(runoff, equipment washdown, spills, ballast tank water); and
treatment wastes (API separator sludge, float from air
flotation units, sludge from biotreatment).
Since the majority of gasoline components have significant
volatility, land treatment is not usually considered for
treatment of gasoline contaminated soil due to the high
losses of volatiles expected with routine land treatment
operations. Diesel and kerosene type fuels have a
significant portion of volatile components, but "weathered"
wastes that have lost most of the volatile components
usually are suitable candidates for land treatment. Most of
the heavier petroleum products (fuel oils, lubricating oils,
waste sludges and oils) are susceptible to land treatment.
However, the long chain hydrocarbons (20+ carbons) and 5-
6 ring PAHs that may be found in these materials
-------
biodegrade slowly If at all. Petroleum products that consist
mostly of long chain hydrocarbons and other high molecular
weight compounds (asphalts, tars) are not suitable
candidates for land treatment because of the resistance of
such compounds to biodegradation and the physical difficulty
of mixing these products with the soil.
Wood Preserving Contaminants
The major portion of the wood preserving industry in the
United States treats wood under pressure in cylinders with
one of four types of preservatives:
1) pentachlorophenol (penta, PCP) in petroleum, or other
solvents;
2) creosote;
3) water solutions of copper, chromium, and arsenic
(CCA); ammoniacal solutions of copper and arsenic
(ACA); ammoniacal solutions of copper, zinc and
arsenic (ACZA); and
4) fire retardants, which include various combinations of
phosphates, berates or boric acid, and zinc compounds.
A relatively minor portion of the wood treating industry
uses nonpressure treatment of wood with similar
preservatives applied in a variety of ways.
Technical grade pentachlorophenol used for treating wood
contains 85% to 90% pentachlorophenol, remaining
materials being 2,3,4,6-tetrachlorophenol (4% to 8%),
"higher chlorophenols" (2% to 6%), and dioxins and furans
(0.1%). the principal chlorodibenzodioxin and
chlorodibenzofuran contaminants are those containing six to
eight chlorines. Pentachlorophenol is mixed with a carrier
(usually a fuel oil similar to kerosene or diesel fuel) at 4% -
5% pentachlorophenol by weight in the carrier, in order to
produce the solution used for treating wood.
The other major organic wood preservative used in the
United States is coal tar creosote. Creosote is used either
full strength or diluted with petroleum oil or coal tar. Wood
preserving creosote contains approximately 85% polynuclear
aromatic hydrocarbons (PAHs), 10% phenolic compounds,
and 5% nitrogen, sulfur or oxygen containing heterocycles.
The carrier oils for pentachlorophenol and creosote are
similar in biodegradability to the petroleum diesel fuel and
kerosene products. Pentachlorophenol and the associated
phenolics in pentachlorophenol and creosote treating
solutions are biodegradable, though levels of
pentachlorophenol in soil of about 1000 mg/kg are difficult to
bioremediate. Higher pentachlorophenol levels are usually
lowered by mixing with less contaminated soil before land
treatment. The compounds of most interest in creosote are
the PAHs, which vary in susceptibility to bioremediation
according to the number of rings. The two-ring PAHs are
readily biodegradable, the three-ring PAHs are more difficult,
and biodegradation becomes increasingly more difficult for
the four- and five-ring PAHs.
The inorganic wood preservatives will be discussed briefly
since they are not usually remediated by biological means.
Their main impact on bioremediation comes from the
possible toxicity of the inorganic preservatives to
microorganisms, and the necessity for providing means
other than land treatment for remediation of inorganic
contaminated soil. Generally, if soil is contaminated with
organic and inorganic wood preservatives, it is first
bioremediated to treat the organic contaminants, and then
solidified/stabilized to treat the inorganics. There has been
little research on concentrations of the inorganic wood
preservatives that would be problematic in soil
bioremediation.
Levels of Contamination Susceptible to Land
Treatment
The levels of petroleum product contamination amenable to
land treatment vary by waste type and site conditions. In
many cases, soils with higher levels of contaminants than
are recommended for land treatment can be mixed with less
contaminated soil to bring contamination levels down to
recommended starting levels for treatment. Levels of
petroleum product contamination as high as 25% by weight
of soil have been reported as treatable, although experience
indicates that levels 5% to 8% by weight or less are more
readily treated. Long chain hydrocarbons (20 or more
carbons in the chain) are more resistant to biological
treatment, so petroleum products containing excessively
high percentages of these compounds (bunker C, asphalt,
tars, etc.) are not good candidates for land treatment under
most commonly established cleanup standards for soil.
Soil contaminated with 15,000 to 20,000 mg/kg dry weight
creosote wastes have been treated in soil systems, although
more usual starting levels are in the 5,000 to 10,000 mg/kg
range. Pentachlorophenol wastes are rarely treated at more
than 1000 mg/kg starting levels since pentachlorophenol is
quite toxic to microorganisms at the higher levels.
The final levels attainable also vary by waste and site
conditions. Generally, once total contaminant levels are
below 50-200 mg/kg PAH, remediation by land treatment is
slow, and further treatment by conventional land treatment
techniques may be ineffective. For instance, land treatment
of creosote wastes is generally considered successful if total
carcinogenic polynuclear aromatic hydrocarbons are
reduced to below 50-100 mg/kg, and specific components
are reduced to their "land ban" levels (for instance, pyrene to
7 mg/kg). Laboratory treatability studies may be used to
assess the "best case" potential for final contaminant levels,
with the assumption that actual final levels in the field would
rarely be lower than those found in the laboratory study.
-------
BIBLIOGRAPHY
Land Treatment Concept References
Bulman, T.L, S. Lesage, P.J.A. Fowlie, and M.D. Webber.
November 1985. The Persistence of Polynuclear Aromatic
Hydrocarbons in Soil. PACE Report No. 85-2. Petroleum
Association for Conservation of the Canadian Environment.
1202-275 Slater Street. Ottawa, Ontario.
Loehr, R. 1989. Treatability Potential for EPA Listed
Hazardous Chemicals in Soil. U. S. Environmental
Protection Agency, Robert S. Kerr Environmental Research
Laboratory, Ada, OK, EPA/600/2-89/011.
Loehr, R.C., and J.F. Malina, Jr., Ed. 1986. Land
Treatment: A Hazardous Waste Management Alternative.
Water Resources Symposium Number Thirteen. Center for
Research In Water Resources, Bureau of Engineering
Research, College of Engineering, The University of Texas
at Austin. Austin, Texas.
Lynch, J., and B.R. Genes. 1989. Land Treatment of
Hydrocarbon Contaminated Soils. In: Petroleum
Contaminated Soils, Vol. 1: Remediation Techniques,
Environmental Fate, and Risk Assessment, P. T. Kostecki
and E. J. Calabrese, Eds., Lewis Publishers, Chelsea, Ml, p.
163.
Park, K.S., R.C. Sims, R.R. Dupont, W.J. Doucette, and J.E.
Matthews. 1990. Fate of PAH Compounds in Two Soil
Types: Influence of Volatilization, Abiotic Loss and
Biological Activity. Environ. Toxicol. Chem., 9:187.
Rochkind, M.L, J.W. Blackburn, and G.S. Sayler. 1986.
Microbial Decomposition of Chlorinated Aromatic
Compounds. EPA/600/2-86/090, Hazardous Waste
Engineering Research Laboratory, U. S. Environmental
Protection Agency, Cincinnati, OH.
Ross, D., T.P. Marziarz, and A.L Bourquin. 1988.
Bioremediation of Hazardous Waste Sites in the USA: Case
Histories. In: Superfund '88, Proc. 9th National Conf.,
Hazardous Materials Control Research Institute, Silver
Spring. MD, p. 395.
Sims, J.L., R.C. Sims, and J.E. Matthews. Bioremediation of
Contaminated Surface Soils. August 1989. U.S.
Environmental Protection Agency, Robert S. Kerr
Environmental Research Laboratory, Ada, OK, EPA-600/9-
89/073.
Sims, R.C., D. L. Sorensen, J.L. Sims, J. E. McLean, R.
Mahmood, and R. R. Dupont. 1984. Review of In-Place
Treatment Technologies for Contaminated Surface Soils-
Volume 2: Background Information for In-situ Treatment.
U.S. Environmental Protection Agency, Risk Reduction
Research Laboratory, Cincinnati, OH, EPA-540/2-84-003b.
Sims, R.C., W.J. Doucette, J.E. McLean, W.J. Grenney, and
R.R. Dupont. 1988. Treatment Potential for 56 EPA Listed
Hazardous Chemicals in Soil. U.S. Environmental Protection
Agency, Robert S. Kerr Environmental Research Laboratory,
Ada, OK, EPA/600/6-86/001, April.
St. John, W.D., and D.J. Sikes, 1988. Complex Industrial
Waste Sites. In: Environmental Biotechnology-
Reducing Risks from Environmental Chemicals through
Biotechnology, G.S. Omenn, Ed., Plenum Press, New
York, NY, p. 163.
U.S. EPA. 1989. Guide for Conducting Treatability Studies
under CERCLA. U.S. Environmental Protection Agency,
Office of Solid and Emergency Response and Office of
Research and Development, Washington, DC, Contract No.
68-03-3413. November.
U.S. EPA. 1990. Handbook on In Situ Treatment of
Hazardous Waste-Contaminated Soils. U.S. Environmental
Protection Agency, Risk Reduction Research Laboratory,
Cincinnati, OH. EPA/540/2-90-002, January.
U.S. EPA. 1986. Permit Guidance Manual on Hazardous
Waste Land Treatment Demonstrations. EPA-530/SW-86-
032, Office of Solid Waste and Emergency Response, U.S.
Environmental Protection Agency, Washington, DC.
U.S. EPA. 1991. On-Site Treatment of Creosote and
Pentachlorophenol Sludges and Contaminated Soil. EPA/
600/2-91/019. Extramural Activities and Assistance
Division, Robert S. Kerr Environmental Research Laboratory,
Ada, OK. May.
Soil Properties References
Dragun, J. The Soil Chemistry of Hazardous Materials.
Hazardous Materials Control Institute, Silver Spring, MD.
Foth, H.D. 1990. Fundamentals of Soil Science, Eighth
Edition. John Wiley & Sons, New York, NY.
McLean, Joan C., and Bert E. Bledsoe. Behavior of Metals
in Soils. Ground Water Issue. EPA/540/S-92/018. October
1992. Superfund Technology Support Center For Ground
Water, Robert S. Kerr Environmental Research Laboratory,
Ada, OK.
Paul, E.A., and F.F. Clark. 1989. Soil Microbiology and
Biochemistry. Chapter 2—Soil as a Habitat for Organisms
and Their Reactions. Academic Press, San Diego, CA.
Monitoring References
Blackwood, Larry G. Assurance Levels of Standard Sample
Size Formulas: Implications for Data Quality Planning.
Environmental Science and Technology. Vol. 25, No. 8,
1991.
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Eklund, Bart. Practical Guidance for Flux Chamber
Measurements of Fugitive Volatile Organic Emission Rates.
J. Air Waste Management Association, 42:1583-1591.
December 1992.
Englund, E.J., Weber, D.D., and N. Leviant. EPA/600/J-92/
166. NTISPB92-180314. 1992. The Effects of Sampling
Design Parameters on Block Selection. USEPA
Environmental Monitoring Systems Laboratory. Las Vegas,
NV.
Hawley-Fedder, Ruth and Brian D. Andresen. Sampling and
Extraction Techniques for Organic Analysis of Soil Samples.
UCRL-ID-106599. February 12,1991. Lawrence Uvermore
National Laboratory.
Gilbert, R.O. Statistical Methods for Environmental Pollution
Monitoring. 1987. Van Nostrand Reinhold. ISBN 0-442-
23050-8.
Gilbert, R.O., and J.C. Simpson. An Approach for Testing
Attainment of Soil Background Standards at Superfund
Sites. (American Statistical Association 1990, Joint
Statistical Meetings, Anaheim, CA. August 6-9,1990.)
Pacific Northwest Laboratory, Richland, WA 99352.
Keith, Lawrence H., Ed. Principles of Environmental
Sampling. 1988. American Chemical Society. Washington,
DC.
T.E. Lewis, A.B. Crockett, R.L. Siegrist, and K. Zarrabi. Soil
Sampling and Analysis for Volatile Organic Compounds.
Ground-Water Issue. EPA/540/4-91/001. February 1991.
USEPA Environmental Monitoring Systems Laboratory. Las
Vegas, NV.
U.S. EPA. A Guide: Methods for Evaluating the Attainment
of Cleanup Standards for Soils and Solid Media. Quick
Reference Fact Sheet. Publication: 9355.4-04FS. July
1991. Office of Emergency and Remedial Response,
Hazardous Site Control Division OS-220W.
U.S. EPA. Permit Guidance Manual on Unsaturated Zone
Monitoring for Hazardous Waste Land Treatment Units.
EPA/530-SW-86-040. October. USEPA Environmental
Monitoring Systems Laboratory, Las Vegas, NV 89114.
U.S. EPA. 1991. Handbook of Suggested Practices for the
Design and Installation of Ground-Water Monitoring Wells.
EPA/600/4-89/034. March. USEPA Environmental
Monitoring Systems Laboratory, Las Vegas, NV. 89193-
3478.
Petroleum Contaminant References
Drews, A.W., Ed. Manual on Hydrocarbon Analysis: 4th
Edition. ASTM Manual Series: MNL 3. ASTM, 1916 Race
Street, Philadelphia, PA. 19103.
Hoffman, H.L Petroleum—Petroleum Products. Kirk-
Othmer Encyclopedia of Chemical Technology. 3rd Ed. Vol
17. Gulf Publishing Company.
Miller, Michael W. and Dennis M. Stainken. An Analytical
Manual for Petroleum and Gasoline Products for New
Jersey's Environmental Program, in: Petroleum
Contaminated Soils. Volume 3. Paul T. Kostecki and
Edward J. Calabrese. Technical Editor Charles E. Bell.
Lewis Publishers. 1990.
Wood Preserving Contaminant
References
USDA. 1980. The Biologic and Economic Assessment of
Pentachiorophenol, Inorganic Arsenicals, Creosote. USDA,
Number 1658-11. Washington, DC.
A Technology Overview of Existing and Emerging
Environmental Solutions for Wood Treating Chemicals.
December 1990. National Environmental Technology
Applications Corporation. University of Pittsburgh Applied
Research Center.
Becker, G. 1977. Experience and Experiments with
Creosote for Crossties. Proc. Am. Wood-Pres. Assoc.
73:16-25.
Bevenue, A. and H. Beckman. 1967. Pentachiorophenol:
A Discussion of Its Properties and Its Occurrence as a
Residue in Human and Animal Tissues. Residue Rev.
19:83.
Buser, H.R. 1975. Polychlorinated Dibenzo-p-dioxins,
Separation and Identification of Isomers by Gas
Chromatograpny-Mass Spectrometry. J. Chromatog.
114:95-108.
Buser, H.R. 1976. High Resolution Gas Chromatography of
Polychlorinated Dibenzo-p-dioxins and Dibenzofurans. Anal.
Chem. 48:1553.
Crosby, D.G. 1981. Environmental Chemistry of
Pentachiorophenol. Pure Appl. Chem. 53:1052-1080.
DaRos, B., R. Merrill, H.K. Willard, and C.D. Wolbach.
Emissions and Residue Values from Waste Disposal During
Wood Preserving. Project Summary. EPA-600/S2-82-062.
August 1982.
USEPA. 1978. Report of the Ad Hoc Study Group on
Pentachiorophenol Contaminants. Environmental Health
Advisory Committee. Science Advisory Board, Washington,
DC.
Hoffman, R.E., and S.E. Hrudley. Evaluation of the
Reclamation of Decommissioned Wood Preserving Plant
Sites in Alberta. Waste and Chemicals Division and
H.E.L.P. Project, Alberta Environment.
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JR8 Associates, Inc. Wood Preserving: Preliminary Report
of Plants and Processes. 1981. National Institute for
Occupational Safety and Health.
Lorenz, LR. and LR. Gjovik. 1972. Analyzing Creosote by
Gas Chromatography. Relationship to Creosote
Specifications. Proc., Amer. Wood Pres. Assoc. 68:32-42.
Micklewright, James T. Wood Preservation Statistics, 1988.
A Report to the Wood-Preserving Industry in the United
States. 1990 Proceedings of the American Wood
Preservers' Association.
Nicholas, Darrel D., Ed. Wood Deterioration and Its
Prevention by Preservative Treatments. Volume II:
Preservatives and Preservative Systems. Syracuse
University Press. 1973.
Thompson, Warren S., and Peter Koch. Preservative
Treatment of Hardwoods: A Review. USDA Forest Service.
General Technical Report SO-35. 1981.
almost pure organic matter is called the "0" horizon. As soils
mature, clay particles are moved downward along with
water. The clay tends to accumulate in lower soil layers.
The zone of clay accumulation is called the B horizon. The
C horizons comprise the relatively undifferentiated material,
often distinguished from the parent rock only by the lack of
consolidation.
Depth
Soil depth to bedrock or ground water affects the volume of
soil that may be contaminated, potential directions of
contaminant movement, and the difficulty of access to the
contaminated volumes of soil. Land treatment uses the
concept of a "treatment zone," meaning a zone in which
migrating contaminants are adsorbed and degraded. The
depth and activity of this zone affects the potential for
migration of contaminants to ground water.
Texture
APPENDIX A
SOIL PROPERTIES
Soils are composed of organic matter, inorganic solids
(sand, silt, clay, and larger fragments), air, and water.
Organic matter may range from less than one percent in
many soils, especially those in hot or cold desert climates, to
50% or more in the peat soils found in peat bogs. Soils are
generally classified according to their sand, silt and clay
content; the ratios of these components may vary in almost
any proportion. Air and water occupy the pore spaces
among the sand, silt and clay particles. Pore space
occupies about 20% - 60% of most uncompacted soils.
Soil parameters important in land treatment include: soil
horizons, depth, texture (grain size distribution—sand, silt,
clay proportions), bulk density, porosity (effective, total),
hydraulic conductivity, permeability, tilth, cation and anion
exchange capacity, organic matter content, pH, water
content and water holding capacity, nutrient content, salinity,
redox potential, color, and biological activity.
Soil Horizons
Soil horizons are the various layers present in most soil
columns. Physical and chemical differences between soils
in the layers affect movement of contaminants through the
soil profile. Organic matter from dead plants and animals
accumulates in the upper, "A" horizons. A top layer of
Soil texture (as defined by the proportions of sand, silt, clay)
influences porosity, hydraulic conductivity, permeability, tilth,
cation exchange capacity (CEC), and sorption capacity for
contaminants. Finer textured soils have greater surface
areas per unit volume. The differences between the
chemical and physical properties of the various sands and
silts is largely due to the different particle sizes. Clays are
not only much smaller than sands and silts but also are quite
different in chemical composition. Clay particles have
negatively charged surfaces that attract and hold cations
(Ca~, Na*, NH4*, H*, etc.) or other materials with a positively
charged portion, giving rise to a cation exchange capacity.
The edges of the clay particles may also have a positive
charge, giving rise to an anion exchange capacity. Clay
particles are flat, platelike structures, with a very high surface
area. Clay particles have interior layers that can separate
enough to allow water and many ions to enter and be held.
"Shrink-swell" clays allow much water to enter these interior
areas, causing the clay particles to change greatly in volume
as the moisture content changes.
Bulk Density
The soil bulk density is the mass of dry soil per unit bulk
volume. The bulk volume is determined before drying the
soil to obtain the mass. Bulk density is used in most soil
transport and fate models.
Porosity, Hydraulic Conductivity, and
Permeability
Porosity, hydraulic conductivity, and permeability are three
parameters that are closely related and commonly confused.
The terms describe the soil characteristics and rate of water
movement through the soil.
10
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Porosity is the ratio of the volume of void spaces in a soil to
the total volume of the soil. The void spaces may be
occupied by air, water, or other fluids, such as contaminants.
The effective porosity represents the interconnection
between the void spaces and is defined as the volume of
void spaces through which water or other fluids can travel,
divided by the total volume of the soil.
Primary porosity is a characteristic of the original soil or rock
matrix; secondary porosity is caused by weathering or
fracturing processes occurring after the soil or rock was
emplaced. Secondary porosity can greatly enhance the
effective porosity of the soil or rock.
Typically, more rounded particles such as gravel, sand, and
silt have lower porosities than soils rich in the platy clay
minerals. Soils containing a mixture of grain sizes will also
exhibit lower porosities. The smaller particles tend to fill in
void spaces between the larger ones.
Porosity can be an important controlling influence on
hydraulic conductivity, which is a proportionality constant
describing the rate at which water can move through the soil.
Hydraulic conductivity is a function of the properties of both
the porous medium and the fluid passing through it.
Typically, the hydraulic conductivity has higher values for
gravel and sand and lower values for clay. Thus, even
though clay-rich soils usually have higher porosities than
sandy or gravelly soils, they usually have lower hydraulic
conductivities, because the pores in clay-rich soil are much
smaller.
The hydraulic conductivity can vary over 13 orders of
magnitude, depending on the type of material and whether
the measurement was made in the field or in the laboratory.
The methods of measurement differ significantly, and
interpretations placed on the values may be dependent on
the type of measurement. In practical terms, this implies that
an order-of-magnitude knowledge of hydraulic conductivity
may be all that is attainable, and that decimal places beyond
the second probably have little significance.
Pore spaces may be classified according to size as
micropores and macropores. Porosity of sandy soils largely
consists of macropores, while porosity of clay soils is largely
micropores. The ratio of micropores to macropores
influences the movement of soil gases and water in the soil
and is of particular importance for bioremediation, since the
ratios and interactions of soil gas and water greatly influence
microbial activity.
Permeability describes the conductive properties of a porous
medium independently of the fluid flowing through it. It
includes the influence of media properties that affect flow,
including the grain size.distribution and roundness, and the
nature of their arrangement. Permeability is widely used in
situations where multiphase flow systems (vapor, water, and
nonaqueous phase liquids) are present.
These conductive properties determine the feasibility of
adding or removing materials such as water, air, and
nutrients to the soil. Soil hydraulic conductivities of about
1.0 X 10-1 to 1.0 X 10* cm/sec are favorable for adding or
removing materials. Soils with conductivities above this
range may require careful management to prevent excessive
drainage or contaminant mobility for some remediation
technologies: in soils with conductivities below this range it
may be difficult to add or remove materials for remediation.
The hydraulic conductivity of saturated soils is a function of
the grain size and sorting of the particulate materials, and
therefore, is somewhat stable over time. Hydraulic
conductivity in unsaturated soil is not only influenced by
grain size and sorting but also is strongly influenced by water
content of the soil. At low soil water content, soil water
moves largely in response to adhesive and cohesive forces
in the soil, which are measured as matric potential. Soluble
contaminants in unsaturated soil move in the thin films of
water surrounding the soil particles. The thicker the film of
water (e.g., the wetter the soil), the larger the conduit for
contaminant movement, and more of the contaminant that
can move in a given period of time.
Movement of contaminants in the vadose zone is usually in
the soil gas, pore water or as nonaqueous phase liquids
(NAPLs). Soil gases may move into the atmosphere, ground
water, soil pore water, be adsorbed on soil particles or
undergo chemical/biological transformation. Dissolved
contaminants in soil water undergo similar changes. NAPLs
move in response to gravity and changes in soil
permeability.
Soil Moisture and Water Holding Capacity
Soil moisture holding capacity is determined by the
proportion of clay and organic matter in the soil. Clays and
organic matter tend to hold larger amounts of water relative
to their volume than do the coarser grained silts and sands.
When a soil is saturated with water, then allowed to drain
freely for 24 hours, the soil is said to be at field capacity.
Essentially this means that the soil micropores are filled with
water, and the macropores are filled with air.
The ratio of air and water in the soil strongly influences many
important processes in the soil. Aerobic microbial activity is
usually optimum when soil moisture is about 70% - 80% of
field capacity; the higher end of the range is more desirable
for coarser soils. Relatively dry soils tend to adsorb many
contaminants more strongly than wetter soils, since water
competes with the contaminants for adsorption sites. When
the soil is not saturated, water and water-soluble compounds
may move in any direction in the soil in response to matric
potential, whereas water in saturated soils moves largely in
response to gravity. Water and water-soluble compounds
move faster through wetter soils than drier soils. Very dry
soils, especially soils with high organic matter content, may
be very difficult to wet since dry organic matter tends to be
hydrophobic. NAPLs may move through moderately wet
soils faster than either dry or very wet soils, since dry soils
tend to adsorb much of the NAPL and the pores full of water
in wet soils inhibit NAPL movement.
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Tilth
Tilth refers to ability of the soil to undergo manipulation
(plowing, tilling) and retain a desirable loose, friable structure
that promotes ready movement of water and air. Structure
refers to the tendency of soil to agglomerate into units called
peds, granules or aggregates. In surface soils, this
agglomeration is influenced by the microbial secretion of
polymeric materials that cement soil materials together into
small particles. High levels of sodium in the soil (measured
as exchangeable sodium percentage (ESP) or sodium
absorption ratio (SAR)) may disperse the soil particles
causing a loss of structure. Sodium absorption ratios higher
than 15 may indicate a problem, as do ESP values greater
than 10% of the cation exchange capacity (CEC) in fine
textured soils and greater than 20% of the CEC in coarse
textured soils.
Sorptive and Exchange Capacity
Clay materials in soils generally have a high adsorptive
capacity for many organic and inorganic materials. Coarse,
sandy soils may allow rapid movement of relatively small
amounts of contaminants into lower soil layers and aquifers,
while soils high in clay may significantly retard movement of
many contaminants. Inorganics and some organics may be
influenced by the CEC, which denotes the capacity of the
clay particle for adsorption of positively charged materials on
the negatively charged surfaces of the clay. Mobility of
metals in the soil may be greatly affected by the CEC. Clays
may have an anion exchange capacity due to the positive
charge on the edges of some clay particles. The anion
exchange capacity is usually less than the cation exchange
capacity. Clays also will adsorb uncharged molecules due to
Van der Waals interactions of the uncharged materials with
clay particles.
Organic Matter
Soil organic matter is generally composed of 25% - 35%
polysaccharides and protein-like compounds which are
readily decomposed by microorganisms and therefore have
a short halflife in soils. About 65% - 75% of the soil organic
matter is composed of humic materials, which are complex
mixtures of high molecular weight organics and are resistant
to degradation. These percentages do not include those
organic compounds that may be present as contaminants;
i.e., oil and grease, volatile organics, etc. Soils high in
organic matter will adsorb significant quantities of organic
contaminants, since organic compounds have a strong
tendency to adsorb onto soil organic matter, thereby slowing
movement. Soil organic matter usually has a relatively high
CEC and may have a significant anion exchange capacity,
although anion exchange capacity is usually much less than
the CEC. Increased soil organic levels are generally
favorable to microbial activity, due to increased CEC, tilth,
water holding capacity, and available carbon. Soil organic
matter levels tend to be lower in warm, moist climates, since
these conditions allow rapid microbial oxidation of the
organic matter. Soil organic matter may be increased by
addition of straw, hay, sawdust or wood chips, manures, and
many other organic materials. Addition of easily transformed
organic materials may cause shortages of nutrients
(particularly nitrogen and phosphorus) due to the increased
microbial population feeding on the added organic matter.
PH
The pH of the soil affects microbial activity, availability of
nutrients, plant growth, immobilization of metals, rates of
abiotic transformation of organic waste constituents, and soil
structure. A pH range of 6-8 is considered optimum for
bioremediation in most cases. Most metals tend to be less
mobile in high pH soils (arsenic is an exception), but acidic
organics such as pentachlorophenol are more mobile. Soils
with high sodium levels and high pH (most often found in dry
climates) tend to deflocculate and crust, limiting oxygen
diffusion and water uptake. Soil pH may be lowered by
addition of ferrous or aluminum sulfate, elemental sulfur or
sulfuric acid; soil pH may be raised by addition of agricultural
lime.
Nutrients
Nutrient content relates to the concentration of nutrients
available for use by microorganisms. Nitrogen and
phosphorus often limit microbial activity in soils. An organic
carbon:nitrogen:phosphorus ratio of 100-300:10:1 is
recommended to stimulate microbial activity, with the lower
C:N ratios recommended when most of the carbon is in a
readily degradable form. The percent base saturation, a
general indicator of soil fertility, is defined as the total of the
four principal exchangeable bases (calcium, magnesium,
sodium, potassium) divided by the total exchange capacity of
the soil. A base saturation of about 80% is desirable, with
calcium comprising about 60% - 70% of the CEC and
potassium about 5% -10% of the CEC.
Most soils have low levels of nitrogen, although soils with
high levels of organic matter may have significant amounts
of nitrogen as part of the organic matter; this nitrogen is
usually released slowly as the organic matter decomposes.
Inorganic nitrogen in the soil is usually quite water soluble
and therefore readily lost to leaching, which may cause
ground water pollution problems. Since microorganisms
benefit from a steady supply of nitrogen, it is advantageous
to supply nitrogen either in small amounts frequently or in a
form (e.g., as organic fertilizers or "slow-release" inorganic
fertilizers) that supplies nitrogen to the microorganisms
slowly.
Many soils contain significant quantities of phosphorus, but
the phosphorus may be strongly bound in the soil, and little
may be readily available to the microorganisms. Usually
bound phosphorus is in equilibrium with phosphorus
dissolved in the soil water; the equilibrium is heavily
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weighted toward the bound form. For this reason,
phosphorous fertilizers are often applied to raise the amount
of phosphorus in the soil water.
Salinity
The electrical conductivity (EC) of a soil reflects the soluble
salt content (salinity). An EC of 2 or less indicates that
salinity is not a problem in most instances. An EC of 2-4
may inhibit activity of very salt-sensitive microorganisms,
while an EC of 4-8 may restrict activity of many
microorganisms. An EC greater than 8 will restrict activity of
most microorganisms.
Redox Potential
The redox potential of the soil (oxidation-reduction potential,
reported as Eh) is controlled by the concentration of 02 in the
gas and liquid phases. The O. concentration is a function of
the rate of gas exchange with the atmosphere and the rate
of respiration in the soil. Respiration in the soil may deplete
Oj, lowering the redox potential and creating anaerobic
(reducing) conditions. These conditions are unfavorable to
aerobic biotransformation, but may promote anaerobic
processes such as reductive dehalogenation. Many reduced
forms of polyvalent metal cations are more soluble (and
mobile) than their oxidized forms. Well aerated soils have
an Eh of about 0.8 to 0.4 volts; moderately reduced soils are
about 0.4 to 0.1 V; reduced soils are about 0.1 to -0.1 V; and
highly reduced soils are about -0.1 to -0.3 V. Redox
potentials are difficult to measure and are not widely used in
the field.
Color
The color of soils is largely due to chemical changes and
organic matter content. Dark colors in soil are caused by
highly decayed organic matter. Reds and yellows are
caused by oxidized and hydrated iron in soil minerals.
Uniform reds, yellows, and browns indicate that a soil is well
drained. Mottled grays or blues may indicate poor drainage.
The location of any mottled layers may indicate the level of
the seasonal high water table.
Biological Activity
Biological activity in the soil is affected by all of the soil
characteristics discussed in this Appendix. Biological activity
apparently accounts for most of the transformation of organic
contaminants in soil.
Both bacteria and fungi have been shown to be important in
bioremediation processes. Most research in bioremediation
has centered on bacteria, but some investigators have found
that fungi can play an important role in bioremediation
processes, especially with halogenated compounds (e.g.,
pentachlorophenol). In most cases bioremediation relies on
communities of microorganism species, rather than one or a
few species. Bioremediation consists of utilizing techniques
for enhancing development of large populations of
microorganisms that can transform pollutants of interest, and
bringing these microorganisms into intimate contact with the
pollutants. In order to do this efficiently, necessary conditions
for the growth and activity of the microorganisms must be
maintained.
Microbial activity in the soil can be estimated by using plate
counts, most probable number (MPN) counts, direct
microscopic counts, respiration measurements, ATP activity
measurements, and others. Unfortunately, the relationship
of these measurements to practical use of bioremediation
techniques is unclear, at best Generally use of these
measurements is limited to determining if soil conditions or
waste characteristics are suitable for microbial activity, and
whether particular management techniques have enhanced
microbial activity.
By culturing soil microorganisms on special media, counts of
"specific degraders" can be determined. For instance, if
PAHs are added to a media with no other carbon sources
present, any microorganisms that grow can be assumed to
have the capability of using PAHs as a sole source of
carbon. Again, the relationship of these counts to actual
biodegradation in the field is unclear.
If biodegradable contaminants have been present in the soil
for more than a few months or years, and microorganisms
are able to grow and reproduce in the contaminated soil,
microorganisms that can transform the wastes are likely to
be present Treatability studies can be used to determine
techniques that might be appropriate to optimize their
transforming activity, as well as determine if the
microorganisms are capable of transforming the wastes
to acceptable levels of acceptable end products in an
acceptable time frame.
Bioaugmentation commonly takes two forms.
Microorganisms may be isolated from the site in question,
cultured in quantity and added to the site soil, or
microorganisms isolated from other sites may be cultured
and added to the site soil. It is very difficult to show that
added microorganisms survive and grow in the soil, and
even more difficult to show that the added microorganisms
have any significant affect on transformation.
Metals in Soils
The mean concentrations of metals commonly found in
uncontaminated soils are shown in Table A-2. The actual
"background" concentrations at a given site may vary widely
from these numbers. High concentrations of certain metals
(particularly the "heavy" metals lead, mercury, cadmium,
chromium and others) are known to inhibit microorganism
activity in laboratory studies, but the particular levels of
metals that would be of significance in field bioremediation
are not known with certainty. The influence of metals
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concentration on bioremediation appears to be site,
contaminant, and microorganism dependent. In cases
where high concentrations of metals appear to be of
concern, testability studies should be conducted to
determine the influence of metals concentrations on
bioremediation.
TABLE A-2. MEAN CONCENTRATION (MG/KG) OF METALS IN THE EARTH'S CRUST AND SOILS a
Al Fe
Mn
Bo Cu Cr Cd Zn As So
Ba
HI
Ag Pt> Hg
Soils 72000 26000 550 0.92 25 54 0.35 60
Crust 82000 41000 350 2.6 50 100 0.11 75
7.2 0.39 580
1.5 0.05 500
19 0.05 19 0.09
80 0.07 14 0.05
a McLean and Bledsoe, 1992
APPENDIX B
MONITORING
The land treatment unit should be monitored to determine
the fate of the contaminants in the unit. Generally, success
in land treatment has been determined by measuring the
disappearance of the waste components. Since waste
components may "disappear from analytical view without
actually being remediated, a mass balance approach should
be taken, monitoring each soil phase (soil solids, gas, water
and nonaqueous phase liquid) to determine how much of
each waste component is in each phase. By this method, it
can be determined whether remediation is actually taking
place or whether the waste components are merely being
moved to different phases. In addition, the toxicity of the
various phases may be monitored to ensure that the
transformation of waste components does not produce more
toxic components, thereby creating a worse problem.
Waste Transformation
Parent Compound Loss
In most cases contaminant monitoring at soil bioremediation
sites is confined to analysis for parent compound loss. This
loss may be due to degradation, fixation, or any other
process that transforms the parent compound or removes it
from the detection ability of the extraction and analytical
method. The power of the extracting solution to remove the
contaminant from the soil matrix is of considerable
importance, since alternating temperature or moisture cycles
can cause waste components to bind so strongly to the soil
that removal is difficult. Parent compound loss is usually
followed even if other monitoring schemes are also used.
Breakdown Products
At some sites analysis for breakdown products may be
conducted, especially if such products are known to have
significant toxicity. Often, the specific breakdown products
are not known; it can be costly to determine the identity of
these products. Usually, breakdown products must be
identified using radiolabeled compounds and gas
chromatography/mass spectrometry (GC/MS) analysis.
Toxicity Reduction
Measures of toxicity may be required to determine if toxicity
of contaminants is actually reduced or if toxic contaminants
are merely transformed to other toxic materials. One assay
commonly used is the Microtox microbial bioassay. Cultures
of phosphorescent (light-emitting) marine bacteria are
exposed to soil extracts, and the decline in light output over
time is measured. The Microtox assay measures general
metabolic inhibition. The major advantages of the assay are
that it is quick, easy, repeatable, inexpensive, and there is a
large amount of published literature about its uses and
results. Its major disadvantage (as for most acute
bioassays) is that results of the assay have no direct
relationship to toxicity of the contaminants of concern to
humans.
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The Ames test, a measure of the mutagenic potential of a
sample, has been used widely in research, though
somewhat less in field applications. There is a high
correlation between mutagenicity (as measured in the Ames
test) and carcinogenicity. The Ames test takes several days
to complete and is more expensive than the Microtox assay.
Bioassays using many other species have been used for
assessing toxicity of environmental samples. Most of these
tests are time consuming and expensive.
Microorganisms
Microbial activity in the soil can be estimated with several
methods, including plate counts, most probable number
(MPN) counts, direct microscopic counts, respiration
measurements, ATP activity measurements, and others.
Unfortunately, the relationship of these measurements to
practical use of bioremediation techniques is not clear.
Generally, use of these measurements is limited to
determining if soil conditions or waste characteristics are
suitable for microbial activity, and whether particular
management techniques have enhanced microbial activity.
Oxygen and carbon dioxide levels can be useful as a
general index of microbial activity. Monitoring oxygen or
carbon dioxide alone can be deceiving since many soil
components can take up or release oxygen or carbon
dioxide by abiotic processes. Monitoring both yields a more
reliable indication of microbial respiration. Soil gas
concentrations of C02 and 02 often fluctuate daily due to
microbial activity; therefore, it is desirable to measure CO2
and O2 at the same time of day for each sampling event.
Since the respiration estimated may not result only from
transformation of the compounds of interest, respiration
cannot be used as a direct measure of transformation of
these compounds.
Soil microorganisms can be cultured on specific media to
determine counts of "specific degraders." If PAHs are added
to a media with no other carbon sources present, any
microorganisms that grow in the media can be assumed to
have the capability of using PAHs as a sole source of
carbon. Again, the relationship of these counts to actual
biodegradation in the field is unclear.
Soil Moisture
Monitoring methods for soil moisture range from "eyeballing"
the soil, to the use of neutron probes. Since soil moisture
appears to be one of the most important determinants of
microbial activity, accurate and reproducible methods of
determining soil moisture are of considerable interest.
Gravimetric methods are very accurate, but somewhat time
consuming, and rarely used in the field. Gypsum block
monitors are often used in research, but are not suited to
LTUs since the blocks require individual calibration, are
permanently installed and would be disturbed by tilling.
Neutron probes are accurate but expensive. The moisture
probes sold in garden supply stores, while inexpensive, are
usually very inaccurate. The moisture monitoring devices
most likely to be useful are those based on the porous cup
tensiometer or soil capacitance. The capacitance based
types are somewhat new, but the porous cup tensiometer
types have been widely used in agriculture, are relatively
simple in concept and use, and are inexpensive.
Nutrients
Soil nutrients are usually determined by a number of
standard tests used in agricultural laboratories. Many land
grant universities have laboratories that analyze soil samples
for farmers, and there are also commercial laboratories
available. In most cases for LTUs, nutrient levels are based
on the ratio of soil carbon to other nutrients. Generally,
carbon to nitrogen to phosphorus (C:N:P) ratios of 100-
300:10:1 in the soil have been used, although some
investigators have found that C:N ratios of 100-120:10 may
be more appropriate where most of the carbon is in a readily
degradable form. Little research has been conducted on the
specific concentrations of nutrients that would be optimal for
LTUs; however, nutrient concentrations for optimal microbial
activity may be similar to that for optimal growth of crop
plants. There is a large variety of material available
concerning nutrient levels versus growth and yield of crop
plants.
SAMPLING STRATEGIES
Sampling program goals must be delineated in order to
decide how m.-.ny samples are needed for a monitoring
program. These goals may be formulated as a statement
that "It is necessary to know the average concentration of
this constituent in the LTU soil to W- 5 ppm." If the variability
of the concentration of this contaminant in the soil is known
(or can be estimated), then statistical formulas can be used
to calculate the number of samples likely to be necessary to
estimate the concentration of that compound to the required
precision. Other goals may also be of interest. For
example, it might be necessary to know the highest
concentration likely to be found, rather than the average. It
also might be desirable to know that the concentration of a
given contaminant does not exceed some given level. The
accuracy needed for monitoring to determine operation and
maintenance practices is usually somewhat less than the
accuracy needed for regulatory monitoring to decide if target
final levels have been achieved. In general, the LTU
monitoring program design is based on the identified data
needs:
1) What are the desired confidence limits for the data? (Is
it sufficient to know the concentration of the contaminant
is some value W-10 ppm, or must the concentration be
known to W- 5 ppm?)
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2) Is knowledge of the average concentration sufficient, or
must it be known if the concentration is less than some
value? (Is it sufficient to know that the average
concentration over the LTD is less than some given
value, or is there a need to be confident that there is no
location in the LTU where the maximum value exceeds
some given value?)
For monitoring purposes LTUs larger than about one acre
should be divided into sections approximately equal in size.
In most cases, sections should be no larger than one acre.
If it is known that certain locations in the LTU have
characteristic high or low concentrations ("hot spots" or "cold
spots"), these locations should be segregated into separate
sections when deciding on the size and coverage of the
sampling sections. This procedure, sometimes known as
"stratified random sampling," yields smaller confidence limits
for the concentrations in the sections. Random locations for
sampling should be determined in each section for each
sampling event.
Locations for collecting samples may be determined by
laying out a grid on the section and either choosing sample
locations from the grid points randomly or in some regular
pattern. If variability within the section is low or unknown, a
regular sampling pattern is probably the best choice. In this
case, the first sampling location would be chosen randomly.
All of the following sampling locations would be chosen
according to a pattern starting from the first randomly chosen
location. If variability within the section is known to be high,
and the approximate locations of high and low spots are
known, the section can be subdivided into similar areas and
each area sampled randomly. There are a number of
methods for choosing sample locations under different
scenarios of contaminant distribution; the references in the
Bibliography section of this document cover the more
commonly used methods.
Concentrations of contaminants in most LTUs are so
variable that many more samples must be taken to achieve
reasonable confidence limits for deciding if regulatory limits
have been achieved. Obviously, the more samples one
analyzes from a given section, the more one knows about
the range of concentrations of the compounds of interest in
that section. However, since analytical costs are usually a
major portion of project costs, the number of samples one
can afford to analyze is limited. Formulas are available to
determine how many samples are necessary to give any
required degree of precision in estimating the mean
concentration or variability of concentration in the plot. Since
the statistical basis for calculating the number of samples to
be taken is moderately complex and beyond the scope of
this brief review, references are provided in the Bibliography.
Compositing of samples eliminates high and low values,
tending to compress all data toward the mean value for the
LTU soil. Compositing decreases apparent variability of the
data by a factor of the square root of (N-1), where N is equal
to the number of subsamples composited to form the sample
for analysis. If the data are used to determine compliance
with maximum contaminant levels, data from composited
samples may indicate compliance has been achieved when
such may not be the case for significant portions of the LTU.
It is commonly supposed that compositing of samples, by
reducing the apparent variability of the data, allows more
accurate statistical analysis. However, data from sample
analyses are used to estimate concentrations and variability
of contaminants in the LTU; no manipulation of samples or
data can actually change the concentrations and variability
of the soil contaminants in the LTU. Since sample
compositing eliminates high and low values from the data,
data from composited samples should be used only to
estimate the mean concentrations of LTU contaminants and
not the range or variability of contaminant concentrations in
the LTU. If it is desirable to know the range and variability of
contaminant concentrations in the LTU, discrete soil samples
should be taken and analyzed.
The amount of sample to be taken (the sample support) is
largely determined by the requirements of the analytical
procedure and any sample archiving required. The larger
the sample, the more likely it is to be representative of the
mean values in the whole section. Usually only a few grams
are needed for analysis, so an aliquot must be taken for
analysis from samples larger than this amount. This usually
involves a mixing procedure in the field or lab, which may
result in the loss of volatile contaminants. Sometimes
subsamples are taken from a number of locations within the
section and composited to make one or more samples for
analysis. The object is to increase the sample support,
making the sample more representative of the section while
minimizing analytical costs. The caveats on compositing
mentioned above also apply here.
The sampling schedule should be based on timing of lift
applications. A lift should be sampled immediately before
application of a new lift. The latest lift applied should be
sampled immediately after application and tilling. Sampling
should be continued on the latest lift at specified intervals
after application until target levels of contaminants are
reached and sustained; then another lift can be applied.
Measuring Transformation Rates
Contaminant transformation rates may be determined to
estimate the time required for treating a number of lifts of
contaminated soil. At least five time-sequence points are
needed to calculate transformation rates for compounds that
degrade in a nonlinear fashion. This category includes most
compounds of regulatory interest. Sampling time points
should be evenly distributed throughout the time frame for
which rate estimates are desired, although it may be
desirable to have more replicate points for the beginning and
ending time points if starting and ending concentrations are
of particular interest. If the number of samples that can be
taken or analyzed is limited, and the time endpoint of the
experiment is not known at the beginning, time spacing
between samples can be increased as the experiment
proceeds. This is common in situations where it is desirable
to reach a given final concentration of a waste component
16
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Rates should not be extrapolated beyond the time frame of
the data from which the rates were calculated. For instance,
in many treatability studies, data from laboratory experiments
that last six months are used to calculate estimated results
for months seven, eight, nine etc. Also, estimation of the
time required for achieving certain contaminant
concentrations is often extrapolated from experimental data
taken from experiments that never reached the levels
desired. Both procedures often result in estimates that are
not verifiable in the field.
Runoff water from the LTU should be sampled after each
major rainfall event if the runoff water is disposed. If the
runoff water is recycled onto the LTU, it can be sampled as
noted for recycled leachate.
Volatilization, Leachate and Runoff
When monitoring the transformation of waste compounds of
interest in the LTU soil, it is important to try to achieve as
complete a mass balance as possible. Routes of loss other
than transformation must also be monitored. Leaching,
volatilization and runoff are usually the most important
alternate routes of loss to be considered in the LTU.
Methods and equipment for monitoring these routes of loss
are discussed below. The location and frequency of
sampling for these routes of loss are subject to the same
considerations as soil sampling as discussed above.
Volatilization is usually measured by collecting volatiles
released from the soil surface. A canopy is placed over a
defined area of contaminated soil and vapors collecting
under the canopy are swept into an adsorbent for later
extraction and analysis. In some cases the vapors may be
measured directly with various kinds of detectors such as
photoionization detectors (PID). Unless the canopy covers
the entire LTU surface without interruption in time or space,
the measurement must be considered as an approximation
of the overall rate of vapor loss. Volatilization is often much
greater immediately after application of a new lift of
contaminated soil or after tilling.
Leaching from in-situ LTUs can be monitored with
lysimeters. Porous cup and pan lysimeters are commonly
used. Porous cup lysimeters have the advantage that they
can be used to take samples of the soil pore water even
when the soil is relatively dry. On the other hand, pan
lysimeters collect only water that is actively moving down
through the soil. Leachate monitoring for ex-srtu LTUs is
relatively straightforward since most ex-situ units have liners
and leachate collection systems to collect leachate that may
be generated. The collected leachate can be sampled
periodically if it is treated separately or disposed. If the
leachate is recycled as irrigation water for the LTU, it should
be sampled at the end of the treatment cycle for each lift to
establish the mass balance for that lift of contaminated soil.
In most cases, installation of monitoring wells downgradient
of the LTU will be required in addition to lysimeters. Usually
at least one monitoring well is placed upgradient of the LTU
to determine if any contaminant detected in a downgradient
well is coming from the LTU or another source of
contamination.
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December 1993
Engineering
Forum Issue
Considerations in Deciding to Treat
Contaminated Unsaturated Soils In Situ
Index
1.0 Introduction
2.0 Critical Factors in Technology Selection
2.1 Technology Characteristics
2.2 Generic Critical Factors for Feasibility
Screening of In Situ Treatment
3.0 Technology-Specific Factors
3.1 Delivery and Recovery Systems
3.2 In Situ Solidification/Stabilization
3.3 Soil Vapor Extraction
3.4 In Situ Bioremediation
3.5 Bioventing
3.6 In Situ Vitrification
3.7 In Situ Radiofrequency Heating
3.8 Soil Rushing
3.9 Steam/Hot Air Injection and Extraction
4.0 Acknowledgments
5.0 References
1.0 Introduction
This Issue Paper was developed for the EPA national
Engineering Forum. This group of EPA professionals,
representing EPA's Regional Offices, is committed to identi-
fying and resolving the engineering issues related to the
remediation of Superfund and RCRA sites. The Forum
operates under the auspices of and advises EPA's Techni-
cal Support Project.
The purpose of this Issue Paper is to assist the user in
deciding if in situ treatment of contaminated soil is a poten-
tially feasible remedial alternative and to assist in the pro-
cess of reviewing and screening in situ technologies. The
definition of an in situ technology is a technology applied to
treat the hazardous constituents of a waste or contaminated
environmental medium where they are located. Central to
the definition of in situ technology is the cbncept that the
contaminated material is not excavated. The technology
must be capable of reducing the risk posed by these con-
taminants to an acceptable level (U.S. EPA, 1990, EPA/
540/2-90/002, p. 1).
Many biological, chemical, and physical mechanisms are
available to treat contaminants in soils. These mechanisms
can be either applied to excavated soil or used in situ. The
costs, logistical concerns, and regulatory requirements
associated with excavation, ex situ treatment, and disposal
can make in situ treatment an attractive alternative. In situ
treatment entails the iise of chemical or biological agents or
physical manipulations to degrade, remove, or immobilize
contaminants without requiring bulk soil removal. Contain-
ment technologies, such as capping, liners, and grout walls,
are not considered in this Issue Paper.
This Issue Paper is intended to assist in the identification
of applicable alternatives early in the technology screening
process. The Issue Paper discusses and lists important
Superfund Technical Support Center
for Engineering and Treatment
Risk Reduction Engineering
Laboratory
Engineering Forum
Technology Innovation Office
Office of Solid Waste and Emergency
Response, U.S. EPA, Washington, DC
Walter W. Kovalick, Jr., Ph.D.
Director
-------
considerations for in situ technologies. More detailed infor-
mation is available on each technology from a variety of
reference sources. These references should be consulted
for all of the technologies that are likely to be useful at a
specific site. In addition to the in situ technologies dis-
cussed in this Issue Paper, technology screening also would
consider potentially useful ex situ technologies. Final tech-
nology selection typically will be based on site-specific
evaluation and treatability testing (U.S. EPA, 1992, EPA/
540/R-92/071a).
Applying the treatment agents to the largely undisturbed
in situ geology gives in situ treatment unique advantages
and challenges. The obvious advantage is that no bulk
excavation is required for in situ treatment. Preventing
excavation eliminates the cost and environmental conse-
quences of moving the contaminated material. The condi-
tions of the subsurface will never be as controlled as in an
ex situ reactor, however. As a result, in situ treatment
requires more extensive site characterization both before
and after treatment, is harder to simulate in the laboratory,
and must be designed and operated to minimize the spread
of contamination.
The principal feature of in situ treatment is controlled
delivery and recovery of energy, fluids, or other treatment
agents to the subsurface. The treatment agent usually is
water, air, or steam but may be energy input by conduction
or radiation. For both physical- and energy-based in situ
treatment agents, controlled application is a key to success.
Systems must be available to apply treatment agents and to
control the spread of contaminants and treatment agents
beyond the treatment zone.
Several in situ technologies also rely on the ability to
recover the treatment agent and contained contaminants
from the subsurface. For example, recovery of flushing fluid
containing contaminants is an integral part of soil flushing,
and the collection and treatment of steam and condensate
' are essential to steam/hot air injection and extraction treat-
ment.
Assessing the feasibility of in situ treatment and selecting
appropriate in situ technologies requires an understanding of
the characteristics of the contaminants, the site, and the
technologies, and of how these factors and conditions
interact to allow effective delivery, control, and recovery of
treatment agents and/or the contaminants.
This Issue Paper discusses established and innovative in
situ treatment technologies that are available or should be
available for full-scale application by 1996. Emerging tech-
nologies that are still being tested in the laboratory and are
not available for full-scale implementation are not discussed.
Examples of emerging technologies include: in situ oxida-
tion or reduction, electrokinetics, hot brine injection, polymer
injection, and soil freezing.
2.0 Critical Factors in Technology
Selection
This section describes critical factors to consider in the
selection of in situ treatment methods and during evaluation
of in situ technologies. Factors to be discussed include the
general technology capabilities and generic critical factors
that influence the general suitability of in situ treatment
when compared to ex situ treatment. Section 3.0 provides
more detailed technology descriptions and the technology-
specific critical factors.
The process for screening and selecting technologies is
described in Guidance for Conducting Remedial Investiga-
tions and Feasibility Studies under CERCLA - Interim Final
(U.S. EPA, 1988, EPA/540/G-89/004). The guidance docu-
ment describes preliminary screening of technologies based
on effectiveness, implementability, and cost The effective-
ness evaluation considers the protection of human health
and the environment and reductions in mobility, toxicity, and
volume of contaminant achieved by an alternative. The
implementability evaluation considers the technical and
administrative feasibility of constructing, operating, and
maintaining a remedial action alternative. The cost evalua-
tion considers the relative cost of alternatives.
This Issue Paper will assist the user in prescreening in
situ technologies for contaminated soil by determining whe-
ther the technologies are technically feasible for a particular
site. This paper is not meant to replace Feasibility Study
Guidance. Consideration and selection of remedial technol-
ogies is based on criteria that are defined by the National
Contingency Plan. This Issue Paper describes the potential
effectiveness of in situ technologies for treating the various
types of chemical groups, and reviews both the general and
the technology-specific factors to consider during preliminary
evaluations of the effectiveness, implementability, and cost
of in situ approaches to treatment Although this Issue
Paper describes only in situ treatment, the user should keep
in mind that selection of in situ technology candidates will
not necessarily eliminate consideration of the ex situ op-
tions. At many sites, both in situ and ex situ technologies
may be competing candidates late in the technology selec-
tion process.
Selecting a technology often requires several iterations
with increasingly well-defined data to refine the selection.
As the project progresses, technology-specific and site-
specific information becomes available. This information
must be used to better define which technologies are suit-
able for waste materials and conditions at the site. As the
decision maker obtains more information about site condi-
tions, waste characteristics, and treatability study results,
this Issue Paper can be used to help further refine selection
of candidate technologies. However, as the list of candi-
dates is narrowed, additional published sources and expert
opinion should be sought to obtain more detailed information
about the candidate technologies.
Treatment of Soils In Situ
-------
2.7 Technology Characteristics
The applicability of the technology to the contaminants
present, the technology maturity, and the ability of the
technology to operate in the unsaturated and/or saturated
zones should be considered in technology selection. The
applicability of the technology to general types of contami-
nants is summarized in Table 2-1. The characteristics of
the technologies are summarized in Table 2-2. Preliminary
selection of technology candidates can be based on the
capabilities of in situ technologies to treat chemical groups
present at the site.
The chemical contaminant groups considered are divided
into three general groups: organics, inorganics, and reac-
tives. The types of organics considered are halogenated
and nonhalogenated volatile organic compounds (VOCs),
halogenated and nonhalogenated semivolatile organic com-
pounds (SVOCs), polychlorinated biphenyls (PCBs),
pesticides, dioxins and furans, organic cyanides, and organ-
ic corrosives. Inorganics are subdivided into volatile metals
(and metalloids), nonvolatile metals, asbestos, radioactive
materials, inorganic corrosives, and inorganic cyanides.
Reactive species may be either oxidizers or reducers. The
types of materials in these subgroups are outlined below.
More detailed lists of constituents within each contaminant
group are given in Technology Screening Guide for Treat-
ment of CERCLA Soils and Sludges (U.S. EPA, 1988,
EPA/540/2-88/004, pp. 10-12).
VOCs are carbon compounds with boiling points lower
than 200°C as analyzed by EPA SW-846 method 8240.
SVOCs are carbon compounds, other than those covered in
the more specific subdivisions, analyzed by EPA SW-846
method 8270. PCBs are any of several compounds pro-
duced by replacing hydrogen atoms in a biphenyl group with
chlorine. Pesticides are compounds other than PCBs ana-
lyzed by EPA SW-846 methods 8080 or 8150. Dioxins and
furans are environmentally persistent, toxic, heterocyclic
hydrocarbons. Organic cyanides are carbon compounds
with a CN group attached. Organic corrosives are carbon
compounds that in aqueous solution have a pH less than or
equal to 2 or greater than or equal to 12.5, or that exhibit a
strong tendency to dissolve materials.
Volatile metals are metals or metalloids where the stable
species in an oxidizing atmosphere (metal or oxide) has a
boiling point less than 630°C. Nonvolatile metals are metals
where the stable species in an oxidizing atmosphere (metal
or oxide) has a boiling point equal to or greater than 630°C.
Asbestos is any of several minerals that readily separate
into long, flexible fibers. Radioactive materials are isotopes
that decay by particle or energy release from the nucleus.
Inorganic cyanides are compounds with a CN group at-
tached. Inorganic corrosives are compounds that in aque-
ous solution have a pM less than or equal to 2 or greater
than or equal to 12.5, or that exhibit a strong tendency to
dissolve materials.
Substances with a strong affinity to acquire electrons are
called oxidizers, whereas substances with a strong tendency
to donate electrons are called reducers.
Treatment often requires a sequence of operations to
deal with a combination of wastes. When evaluating wastes
containing contaminants from more than one chemical
constituent group, each waste group initially should be
considered separately to develop a list of potentially appli-
cable treatment technologies for each chemical group pres-
ent in the soil. The technology lists can be compared to
determine if some candidate technologies are able to treat
all of the groups present.
If one technology is unable to treat all of the groups,
development of a treatment train may be required. For
example at a site with a combination of VOCs and metal
contaminants, soil vapor extraction (SVE) can be used to
remove the VOCs followed by in situ solidification/stabiliza-
tion to reduce the mobility of the metals. The selected
treatment train also must be reviewed for potential interfer-
ences or adverse effects. For example, SVE may increase
the proportion of hexavalent chromium, increasing the
mobility and toxicity of the chromium.
One of the following three characteristics is indicated for
each in situ technology in Table 2-1:
1. Demonstrated Effectiveness - The technology has been
shown to treat some contaminants in the chemical group
to acceptable levels when applied to contaminated soil.
Treatment may involve removal, destruction, immobili-
zation, or toxicity reduction. The demonstration may
have been at the laboratory, pilot, or production scale.
2. Potential Effectiveness - Literature reports indicate there
is or is not a mechanistic basis for the technology to re-
move, destroy, immobilize, or otherwise treat some of the
chemicals in the group when used to treat soil.
3. Possible Adverse Effects - The contaminant is likely to
interfere with the treatment technology or to adversely
affect safety, health, or the environment. Adverse effects
may occur only when the contaminant concentration is
above a threshold level. In many cases, the adverse
effect may be alleviated by pretreatment to reduce the
concentration of the adverse contaminant.
Table 2-2 indicates the maturity of the technology and its
applicability for saturated and unsaturated media. The
maturity is indicated by the ranking shown below (U.S. EPA,
1992, EPA/542/R-92/011, p. 1). Technology maturity is an
important factor in the cost and timeliness of technology
implementation.
1. Established Technology - The technology has been used
on a commercial scale and has been established for use
in full-scale remediations (e.g., incineration, capping,
solidification/stabilization).
2. Innovative Technology - The technology is an alternative
treatment technology (i.e., "alternative11 to land disposal)
for which use at Superfund-type sites is inhibited by lack
of data on cost and performance.
To further assist in the review of technology candidates,
Table 2-2 indicates the media typically treated, typical treat-
ment agents or amendments, and delivery and recovery
methods. Figure 2-1 shows the approximate range of in situ
Treatment of Soils In Situ
-------
Table 2-1. Effectiveness of In Situ Treatment on General Contaminant Groups for Soil
Contaminant Groups
Organic
Inorganic
Reactive
Halogenated Volatlles
Halogenated Semlvolatlles
Nonhalogenated Volatlles
Nonhalogenated Semlvolatlles
PCBs
Pesticides
Dloxlns/Furans
Organic Cyanides
Organic Corrosives
Volatile Metals
Nonvolatile Metals
Asbestos
Radioactive Materials
Inorganic Cyanides
Inorganic Corrosives
Oxidlzers
Reducers
In Situ
Solidification/
Stabilization
(a) (b)
xo>
Y(2)
x<«
Y<2)
T
T
T
T
T
•0)
•
•
•
•
•
T
T
Soil
Vapor
Extraction
(b) (c)
•
T
•
•
Q
Q
G
Q
Q
Q
Q
Q
Q
Q
Q
Q
T
In Situ
Bloremediatlon
(d)
T
T
T
T
T
T
V
T
X
X<5)
X<5)
Q
X
X
X
X
X
Bioventing
(e)
Q
Y<4>
•
•
G
Q
Q
Q
X
X<5>
X<5>
Q
X
X
X
X
X
In Situ
Vitrification
(<»)(0
T
T
T
T
T
T
T
T
T
T
T
T
•
T
T
T
T
Radio-
Frequency
Heating
(0
T
T
•
•
T
T
Q
Q
Q
Q
Q
G
G
G
G
G
G
Soli
Flushing
(b) (g)
• '
T
T
•
T
T
T
T
T
T
•
Q
T
T
T
T
T
Steam Injection
Stationary
System
(b) (f) (h)
•
T
•
T
T
T
T
T
T
Y<6>
Y<6)
G
Y<6)
Y<6>
Y<6)
Y<6>
Y<6>
Mobile
System
(b) (0 (h)
•
Y
•
Y
Q
Q
G
G
Q
Q
Q
Q
G
Q
Q
G
Q
• Demonstrated Effectiveness: Successful treatability test at some scale completed.
T Potential Effectiveness: Mechanistic basis Indicating that technology will work.
Q No Expected Effectiveness: No mechanistic basis indicating that technology will work.
X Potential Adverse Effects.
(1) Vaporization and emission of volatile organic compounds may pose a hazard during mixing.
(2) Semivolalile organics are difficult to treat, but low concentrations of some compounds can be treated.
(3) Arsenic and mercury are difficult to immobilize with cement-based binder formulations.
(4) Possible to treat by cometabolism techniques.
(5) Metals can interfere with bioremediation or bioventing of organics; however, bioremediation methods for low
concentrations of metals are being developed.
(6) Potential effectiveness only for water-soluble compounds.
Adapted from the following sources:
(a) U.S. EPA. 1993. EPA/S30/R-93/012.
(b) Oonehey et al., 1992, pp. 104-105.
(c) U.S. EPA. 1991. EPA/540/2-91/006. p. 2.
(d) U.S. EPA, 1986. EPA/540/2-88/004, p. 13.
(e) U. S. Air Force, 1992. pp. 5-10.
(0 Houthoofd et al.. 1991. EPA/600/9-91/002, pp. 190-203.
(g) U.S. EPA. 1991. EPA/54072-91/021. p. 2.
(h) U.S. EPA. 1991, EPA/540/2-91/005, p. 2.
-------
Table 2-2. Summary of In Situ Technology Characteristics
Technology/Maturity
Solidification/
stabilization (a)(b)
(See Section 3.2)
Established
Soil vapor extraction (b)(c)
(See Section 3.3)
Innovative
In situ bioremediation (d)
(See Section 3.4)
Innovative
Bioventing (e)
(See Section 3.5)
Innovative
In situ vitrification (d)(f)
(See Section 3.6)
Innovative
Radiofrequency heating (f)
(See Section 3.7)
Innovative
Soil flushing (b)(g)
(See Section 3.8)
Innovative
Steam/hot air injection
stationary system (b)(f)(h)
(See Section 3.9)
Innovative
Steam/hot air injection
mobile (auger) system
(b)(f)(h) (See Section 3.9)
Innovative
Media Typically Treated
Saturated or unsaturated soil,
sediment or sludge
Approximate depth limits:
30 feet for auger system,
several feet for in-place mixing,
and not a major constraint for
grout injection
Unsaturated soil
Saturated or unsaturated soil,
sediment, or sludge
Unsaturated soil, sediment or
sludge
Saturated or unsaturated soil,
sediment or sludge
Approximate depth limit 20 feet with
possible extension to 30 feet
Unsaturated soil, sediment or
sludge
Unsaturated or saturated soil
Saturated or unsaturated soil
Saturated or unsaturated soil
Approximate depth limit
30 feet for auger system
Typical Agents or
Amendments
Cement fly ash, blast furnace
slag, lime, or bitumen
Air
Aqueous solution containing an
electron acceptor (typically oxy-
gen), nutrients, pH modifiers, or
additives
Air
Electrical energy by conduction
Electrical energy by radiation
Water, acidic solutions, basic
solutions, chelating agents, or
surfactants
Steam and/or hot air
Steam and/or hot air
Delivery Methods
(see Section 3.1)
Auger mixing, in-place
mixing, or injection
Passive air inlet or
injection wells
Surface infiltration,
tilling, or water injec-
tion wells
Passive air inlet or
injection wells
Electrodes
Radiofrequency
antennae system
Extraction fluid
injection wells
Steam injection wells
Auger mixing
Recovery Methods
(see Section 3.1)
None required
Air extraction wells (off-
gas treatment may be
required)
None required
Air extraction wells may
be used (off-gas
treatment may be
required)
Off-gas collection and
treatment
Off-gas collection and
treatment
Extraction fluid recovery
wells
Condensate recovery
wells and off-gas
collection and treatment
Off-gas collection and
treatment
Adapted from the following sources:
(a) U.S. EPA, 1993, EPA/530/R-93/012.
(b) Donehey et al., 1992, pp. 104,105.
(c) U.S. EPA, 1991, EPA/540/2-91/006, p. 2.
(d) U.S. EPA, 1988, EPA/540/2-88/004, p. 13.
(e) U.S. Air Force, 1992, pp. 5-10.
(f) Houthoofd et al., 1991, EPA/600/9-91/002, pp. 190-203.
(g) U.S. EPA, 1991, EPA/540/2-91/021, p. 2.
(h) U.S. EPA, 1991, EPA/540/2-91/005, p. 2.
Treatment of Soils In Situ
-------
remediation cpsts. The costs shown are based on limited
data reported in the literature. The sources rarely give full
characterization of elements included in the cost estimates.
The ranges should be viewed as preliminary indications of
approximate comparative costs of the various technologies.
Factors Increasing Cost
msituS/s
SVE (Off-Qas Not Treated)
SVE (Off-Gas Treated)
•
Btoremedlation
Btoventing
In Situ Vitrification
Steam/Hot Air Injection and Extraction
Difficult mixing
Small volume treated
Low air oonduetMty
Low air conductivity
Low hydraulic conductivity
Low ambient temperature
Low air conductivity
Low ambient temperature
High moisture
High moisture oonient
High treatment temper ati lie
Low hydraulic conductivity
Expensive solubility
enhancement additives
Low air conductivity
200 400
Treatment Cost (Won)
600
Figure 2-1. Estimated Cost Ranges of
In Situ Remediation Technologies
800
2.2 Generic Critical Factors for Feasibility
Screening of In Situ Treatment
Several critical factors apply to the evaluation of in situ
treatment at most sites. These generic critical factors have
broad application regardless of the specific technology. Rve
categories have been identified to assist in organizing
consideration of the potential feasibility of the in situ treat-
ment for a particular site. This evaluation relates to the
three screening criteria named in the National Contingency
Plan (NCR) instituted by the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA) of
1980 and described in the Guidance for Conducting Reme-
dial Investigations and Feasibility Studies under CERCLA -
Interim Final (U.S. EPA, 1988, EPA/540/G-89/004): effec-
tiveness, implementability, and cost. The five categories are
described in Table 2-3.
These generic factors give an overall framework for
evaluating the potential for using in situ technologies. Site
conditions that give a poor ranking in one or even several
factors do not necessarily indicate that in situ approaches
are unlikely to succeed. All of the generic and technology-
specific factors (see Section 3.0) of in situ and competing ex
situ technologies should be considered to indicate the gen-
eral trend of applicability of in situ treatment and to help
identify possible candidate treatment technologies.
The generic critical factors are geologic and in situ waste
material characteristics that are significant in controlling or
affecting the effectiveness or implementability of in situ
technologies. Although these factors generally are of inter-
est at all sites, some have more effect on the performance
of specific technologies. The user must not draw a conclu-
sion that in situ treatment is inappropriate based on one or
two unfavorable factors. The design features of a particular
technology may be able to eliminate or avoid some of the
limitations inherent with most in situ treatment technologies.
For example, in situ solidification/stabilization (S/S) technolo-
gies using mechanical mixing are less affected by the initial
Treatment of Soils In Situ
-------
Table 2-3. Generic Factors Influencing Selection of In Situ Treatment
Factor Influencing Selection of
In Situ Treatment
Hydrogeologic flow regime
(See Section 2.2.1)
Regulatory standards
(See Section 222}
Time available for remediation
(See Section 22.3)
Removal logistics
(See Section 2.2.4)
Waste conditions
(See Section 2.2.5)
Condition* Favoring Selection of
In Situ Treatment
High or moderate conductivity uniformly distributed in
formation
or
Low-conductivity regions surrounded by regions of high or
moderate horizontal conductivity (a)
Deep water table and/or competent aquitard below
contaminated volume
Wastes that are difficult to treat in accordance with Land
Disposal Restriction (LDR) requirements
Completion time not critical
Large volume of waste
Waste not accessible due to existing structures
Excavation difficult due to matrix characteristics or depth
Poor transportation infrastructure
Large volume of waste
Low contaminant concentrations
Basis
Treatment reagents must reach contaminated
matrix by advective or diffusional flow
Delivery and recovery of treatment agents must
be controlled
LDRs apply to excavated material, unless the
material is excavated and treated within a
Corrective Action Management Unit (CAMU)
In situ treatment requires more time to complete
than ex situ treatment
In situ treatment does not require excavation
It is not economical to excavate large volumes for
treatment of low concentrations
In situ treatment may reduce the need for capital-
intensive treatment equipment
(a) The tow-conductivity regions must be thin* with respect to diffusion path length, which can be feet or inches for gas-phase diffusion in dry soils and inches or less
for water-phase diffusion. (See Table 2-2 for information on type of treatment agent)
soil conductivity than are technologies that require delivery
of fluid flow (see Table 2-2). Moreover, technologies such
as steam injection, in situ vitrification, and radiofrequency
heating, although generally slower than conventional ex situ
methods, can proceed more quickly than in situ bioremed-
iation or soil vapor extraction.
2.2.1 Hydrogeologic Flow Regime
The hydrogeologic flow regime characterizes the gas and
liquid flow in the subsurface. Examination of flow regime
characteristics is directed at answering questions such as
the following:
• Will contaminant removal be achieved at an accept-
able rate?
• Will contaminant removal be complete and uniform?
• Will contaminants or treatment agents escape from the
treatment area?
The flow regime factor is controlled mainly by the amount
of available primary and secondary fluid flow routes, the
magnitude and homogeneity of hydraulic conductivity, fluid
levels and pressures, and the proximity to a discharge loca-
tion. Information needed to define the hydrogeologic flow
regime includes a complete understanding of the geologic
strata and how they were deposited, full characterization of
the fluids and deposits for fluid transmission properties, and
monitoring of soil moisture and water levels through at least
three seasons of one year.
Geologic, hydraulic, and fluid-behavior data are needed
to evaluate the flow regime. Geologic data include, in part,
primary and secondary effective conductivity, history of geo-
logic strata formation, and the stratigraphic and structural
characteristics of the deposit. Hydrologic data include both
surface water and groundwater flow, level, and pressure
characteristics. Surface water data, such as stream/lake
hydrographs and precipitation, infiltration, and recharge
measurements, are needed to understand the general water
balance of the system, whereas groundwater data, including
pressure graphs, well hydrographs, and hydraulic conductivi-
ty and dispersion measurements, are needed to calculate
water and mass flux through the system.
Understanding the spatial variation of conductivity also is
essential to evaluate candidate in situ treatment technolo-
gies. Preferred flow pathways develop in the subsurface
Treatment of Soils In Situ
-------
due either to inhomogeneities in the conductivity or to geo-
logic facies. Most soils have preferential flowpaths that are
responsible for much of the conductivity. The preferential
paths can arise from a number of causes such as root
intrusions, shrink/swell or wet/dry cycling, or uneven settling
(U.S. EPA, 1990, EPA/600/2-90/011, p. 39). These pre-
ferred pathways result in high hydraulic conductivity con-
trasts that can diminish the reliability and efficiency of in situ
treatment methods. Geologic deposits with little or no
vertical fracturing or with no highly developed bedding
planes and those containing hydraulic conductivity contrasts
of less than an order of magnitude will be conducive to in
situ methods. Implementation time will be less and removal
will be more complete when the system tends toward homo-
geneity.
A geology with uniformly distributed high conductivity is
most conducive to application of in situ treatment Hydraulic
conductivity of more than 10"3 cm/sec is most favorable to
technologies that require flow of water solutions (see Table
2-2). For technologies that require air or vapor flow (see
Table 2-2), an air conductivity of more than 10"4 cm/sec is
most favorable (U.S. EPA, 1990, EPA/600/2-90/011, pp. 40
and 54). In situ treatment still can be applied in geologies
with much lower conductivities. However, contaminant
transport in the lower conductivity regions will occur by
slower diffusion processes rather than by bulk material flow.
Feasibility depends on the type of treatment agent, the
contaminant transport mechanisms, and the details of the
distribution of the primary and secondary flowpaths.
Many in situ treatment technologies require injection of
treatment agents such as steam, chemicals, or nutrients.
Often the treatment agents must then be collected from the
subsurface for further processing. The subsurface geology
should be amenable to containment of the treatment agents
in the contaminated area. Containment will be maximized
when vertical and horizontal hydraulic gradients are low or if
the treatment zone is bounded geologically by deposits with
low hydraulic conductivity. Close proximity to groundwater
discharge areas such as streams, lakes, and seeps can
jeopardize containment of in situ treatment agents.
2.22 Regulatory Standards
The regulatory standards factor characterizes the overall
regulatory climate at the site based on federal, state, and
local regulations. Examination of regulatory standards is
directed at answering questions such as these:
• What contaminant cleanup levels are required?
• Are land-use restrictions consistent with the candidate
technologies?
• Will in situ treatment cause unacceptable alteration of
soil conditions?
• Is injection of treatment chemicals consistent with
Land Disposal Restrictions (LDRs) and other regula-
tions, as required?
If the site is a CERCLA site, 40 CFR 300.400(g) requires
that any remedial alternative must satisfy (or provide a
waiver of) all Applicable or Relevant and Appropriate Re-
quirements (ARARs). Applicable requirements include
federal and state environmental standards, cleanup stan-
dards, and control standards that specifically address a
hazardous substance, pollutant, contaminant, remedial
action, location, or other circumstance at a CERCLA site.
Relevant and appropriate requirements are standards that
are not "applicable" but that specifically address a problem
or situation sufficiently similar to those encountered at a
CERCLA site (i.e., their use is well suited to the particular
site).
If the site is not a CERCLA site, it will not need to satisfy
a formal list of ARARs; however, it is probable that certain
regulatory requirements must still be met in the cleanup. In
either case, these requirements will be specific to the site
where treatment will occur and may vary from site to site.
Cleanup levels are one of the most important of the
regulatory requirements that will determine whether in situ
treatment is potentially acceptable. Treatability studies will
help to determine if an in situ treatment method can meet
the required performance levels. For extraction technolo-
gies, the total residual contaminant levels must be deter-
mined to demonstrate remediation. For technologies that
reduce contaminant mobility, such as S/S or in situ vitrifica-
tion, the cleanup levels will be stated in terms of leaching
resistance. Leaching data such as results from the Toxicity
Characteristic Leaching Procedure (TCLP) or other leaching
tests will be needed to demonstrate that the method immo-
bilizes the contaminants. The ability to demonstrate that an
in situ treatment method meets the regulatory performance
requirements will determine the acceptability of that type of
treatment method. Thus, regulatory requirements should be
considered at the screening level to the extent that they are
known. Although the requirements may not have been
finalized at the time screening is conducted, the most cur-
rent list available should be used.
In situ treatment may require more extensive sampling
than ex situ treatment to demonstrate that required treat-
ment performance levels have been achieved. With in situ
treatment, the variation in natural conditions and the distri-
bution of the contaminant must be determined. This often
requires extensive sampling to build a statistical basis for
evaluating whether or not analytical results represent in situ
conditions. In contrast, in a typical ex situ treatment system,
waste material is excavated, prepared, and homogenized as
part of the treatment operation. These homogenized batch-
es can be represented with a smaller number of samples
than corresponding in situ materials.
In the past, regulatory requirements favored in situ
treatment in some cases because excavation of contami-
nated material would have caused it to be treated as a
RCRA waste subject to the treatment standards and Best
Demonstrated Available Technologies (BDATs) under the
LDRs. Recently, however, the EPA published a final rule
allowing the use of Corrective Action Management Units
(CAMUs) at RCRA sites (58 FR 8658, February 16, 1993),
which can eliminate this advantage for in situ treatment.
Although these regulations were developed for corrective |
actions at RCRA facilities, the regulations also may be
Treatment of Soils In Situ
-------
applied as ARARs to CERCLA sites, particularly where
CERCLA remediation involves management of RCRA haz-
ardous wastes. A CAMU is defined as:
'an area within a facility that is designated by the Re-
gional Administrator under part 264 subpart S, for the
purpose of implementing corrective action requirements
under section 264.101 and RCRA section 3008(h). A
CAMU shall only be used for the management of reme-
diation wastes pursuant to implementing such corrective
action requirements at the facility" (40 CFR 260.10).
CAMUs were designed to provide more flexibility in treat-
ment of waste generated during corrective actions. An
important provision of the new regulations is the specifica-
tion in 40 CFR 264.552(a)(1) and (2) that:
"(1) Placement of remediation wastes into or within a
CAMU does not constitute land disposal of hazard-
ous wastes; and
(2) Consolidation or placement of remediation wastes
into or within a CAMU does not constitute creation
of a unit subject to MTRs (minimum technology
requirements)."
As a result, an area or several areas at a RCRA facility (or
CERCLA site) can be designated as a CAMU and the
wastes can be removed from the ground, treated, and
replaced within the boundaries of that CAMU without being
required to comply with the LDR treatment standards.
EPA's goal in issuing these regulations is to encourage the
use of more effective treatment technologies at a specific
site. In situ treatment could still be the favored option at
sites where the Regional Administrator does not establish a
CAMU and where the ex situ treatment is subject to treat-
ment standards and BOAT under the LDRs.
Technologies that accomplish the treatment in situ may
reduce or eliminate point source air emissions or other
discharges. Many in situ treatment technologies, however,
do have aboveground components. For example, materials
are injected; groundwater is extracted, treated, and reinjec-
ted; or vapors are captured and treated. The aboveground
portion still may be subject to appropriate environmental
regulations. Technologies that require injection of fluids
may need to follow Underground Injection Control regula-
tions.
2.2.3 Time Available for Remediation
The available time factor characterizes the amount of
time allowed to set up, operate, and remove the treatment
technology. Determining the time available to complete
remediation is directed at answering questions such as:
• Can the cleanup be completed in a time frame con-
sistent with health, safety, and environmental protec-
tion?
• Can the cleanup be completed in a time frame con-
sistent with end-use requirements?
The time available for remediation is controlled first by
the need to protect human safety and health and the envi-
ronment Remediation must proceed quickly if a toxic
contaminant is present, the contaminant concentration is
high, or the contaminant is mobile and near a critical eco-
system. Time available may be controlled also by the value
or intended end use for the site. It is undesirable to hold a
high-value site out of productive use for a long period.
In situ remediation typically requires more treatment time
than the analogous ex situ treatment technology. In situ
bioremedietion, for example, typically requires about 4 to 6
years (U.S. EPA and U.S. Air Force, 1993, p. 60). Excava-
tion allows essentially immediate remediation of the site.
However, the excavated material often must be shipped and
stored before treatment. Rapid remediation is needed if the
contaminant presents an imminent danger due to hazard
level, mobility, or other factors. Rapid remediation of an
imminent hazard generally favors an ex situ remediation
approach.
The importance of the length of remediation time may be
lessened if the time constraint is driven by economic or end-
use requirements. Many in situ technologies can be applied
concurrently with other site operations. For example, well
and injection/extraction equipment for bioventing, soil vapor
extraction, or fixed-system steam injection do not occupy the
full surface area of a site. Depending on the technology
and the site use, it may be possible to continue routine site
operations during an in situ remediation. However, the need
for rapid remediation still generally increases the favorability
of ex situ treatment technologies.
2.2.4 Removal Logistics
The removal logistics factor characterizes the feasibility
of excavating, handling, and transporting the contaminated
soil. Examination of removal logistics is directed at answer-
ing questions such as:
• Is the material accessible for excavation?
• Can the contaminated soil or water be moved efficient-
ly by conventional bulk material-handling equipment
and techniques?
• Will on-site (and if needed off-site) infrastructure sup-
port transport of waste materials?
Removal logistics are determined by access to the
contaminated site for excavation, the ability to handle
excavated materials, space for placement of ex situ treat-
ment equipment, and the road and rail system on and
around the site.
Data needed to evaluate the removal logistics include a
map of the site showing the general arrangement of struc-
tures and infrastructure and an approximate assessment of
the subsurface conditions such as the location of contami-
nation and the location of major geologic and hydrogeologic
features such as surface water and aquifers.
Treatment of Soils In Situ
-------
Poor removal logistics favor in situ treatment. In situ
treatment generally is favored by conditions such as con*
tamination located under a building that is to remain after
remediation; presence of buried piping or utility lines in the
area; contamination located at great depth or under a rock
formation; poor road or rail access; nearby businesses,
schools, or heavy traffic areas; or site location in a remote
area distant from treatment facilities or sources of backfill.
Contamination located deeper than 5 feet or occupying a
volume of more than 1,000 m3 increases both the cost and
the complexity of excavation (U.S. EPA, 1990, EPA/600/2-
90/01 1, p. 60). Specialized delivery and recovery systems
may be necessary to overcome poor site logistics.
2.2.5 Waste Conditions
The waste conditions factor characterizes the chemical
and physical form of the waste with respect to the ability to
effectively treat or remove the contaminant. Examination of
waste conditions is directed at answering questions such as:
• Are the concentration and distribution of contaminants
consistent with effective in situ treatment?
• Does the waste distribution or condition allow effective
delivery of treatment agents to the contaminant?
The waste conditions factor is controlled by the in situ
conditions of the contaminant and matrix. The conditions
requiring characterization include the concentration and
distribution of the contaminant, the chemical form and spec-
iation of the contaminant and matrix, and physical properties
of the waste and matrix.
Data needed to characterize the waste conditions include
a survey of the location, concentration measurements, and a
description of the form of contaminant, matrix, and debris in
the remediation site. Some soil sampling data may be
available, but assessment of the waste condition at the
preliminary evaluation stage typically will be based largely
on historical records.
The understanding of waste conditions must be constant-
ly reevaluated as additional data are obtained. In addition
to estimating the areal extent and concentration of contami-
nation, the assessment must address the possibility of the
contaminant being contained in drums or tanks and the
potential presence of noncontaminant debris that could
make excavation difficult or obstruct the flow of in situ treat-
ment agents.
In general, contaminants that are either highly concen-
trated or spread over a relatively small area are best treated
by ex situ methods. In particular, contaminants contained in
drums or underground tanks are difficult to treat with in situ
methods. Dilute or widely distributed contaminants tend to
favor in situ treatment. When the contaminant is present at
low concentration, ex situ processing requires excavation,
handling, and, processing of a high proportion of matrix
materials relative to a small amount of contaminant.
3.0 Technology-Specific Factors
This section outlines the characteristics of in situ tech-
nologies and describes factors identified by current testing
programs as influencing the effectiveness, implementability,
and cost of specific in situ treatment technologies. Review-
ing these technology-specific critical factors will help guide
planning of site characterization activities and identification
of technology candidates. Where possible, specific values
are given to indicate what level of a factor is favorable for
application of in situ treatment.
The user must consider all of the generic factors (see
Table 2-3) and technology-specific factors during evaluation
of technology alternatives. The more important factors are
indicated in Tables 3-1 to 3-8 by an asterisk (*) to assist in
the evaluation. However, the evaluation must not focus on
only one factor or one technology. All of the factors should
be evaluated for all technologies that are potentially effective
for the contaminants present at the site. After full consid-
eration of all the factors, the decision maker can examine
the overall indications for favorable and unfavorable trends
to identify technologies with a high probability of being effec-
tive and implementable. The generic factors will help indi-
cate if in situ approaches are generally favored for the site
and contaminants in question. If an in situ technology
seems attractive, the technology-specific factors can help
guide selection of a group of candidates for more detailed
testing and evaluation.
The success or failure of an applied technology often
depends on site-specific conditions or design features.
Selection of technology candidates should be based on site-
specific knowledge and requirements, tempered by the
overall effect of all of the critical factors. Treatability testing
typically will be required to support final technology selection
prior to completion of the feasibility study (FS) or prepara-
tion of the Record of Decision (ROD) (U.S. EPA, 1992,
EPA/540/R-92/071a).
Action levels are provided where possible to give a
starting basis for considering technology alternatives. The
action levels give an approximate "yardstick* to use when
considering technology candidates. However, these single-
value indications cannot characterize or summarize all of the
complex situations that occur in practice. There is no sub-
stitute for experience, site-specific knowledge, and treatabili-
ty testing. The user must be aware of the limitations of
giving a single value to characterize complex interactions.
Site-specific conditions can cause the action levels to be
different at a particular site or with a particular combination
of contaminant and matrix. Design or operating features
may be applied to overcome technology limitations. For
example, at a site where in situ bioremediation is ideal
except for the condition of low soil temperature, a number of
methods are available to improve the soil energy balance.
Many of the technology-specific critical factors show thresh-
old effects. The factor may have an important effect at
some level but have no effect below the cutoff level. For
example, metals such as zinc are trace nutrients at low
levels but toxic to biological systems at higher levels.
10
Treatment of Soils In Situ
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3.7 Delivery and Recovery Systems
Efficient delivery and recovery methods control the
effectiveness, implementability, and cost of in situ treatment.
An array of delivery techniques are available to apply or
inject treatment fluids into the subsurface. The types of
delivery systems for in situ treatment can be classed gener-
ally as gravity driven, pressure driven, auger mixing, and
energy coupling. Recovery systems typically fall in the
gravity-driven or pressure-driven classification (U.S. EPA,
1990, EPA/600/2-89/066, p. 2).
With the exception of radiofrequency heating and in situ
vitrification, the in situ treatment methods discussed below
require delivery and control of liquid, slurry, gas, vapor, or a
combination in the soil. For some technologies (see Table
2-2), the fluids also must be recovered after passing through
the contaminated in situ volume. Fluid delivery may be
accomplished by conventional gravity infiltration through
surface or trench application or by pressure injection
through wells. Conventional recovery methods include
trenches or wells. The conventional methods rely on flow
patterns determined by the design and placement of the
drains or wells and the subsurface stratigraphy. As de-
scribed below, innovative techniques are available to modify
the subsurface conditions to improve flow rates or flow
control.
In situ treatment agents, summarized in Table 2-2, in-
clude fluids delivered to the contaminated volume. Possible
treatment fluids include hot gasses or vapors; water; or
water-containing nutrients, surfactants, anions, cations,
bacteria, S/S binder, or other treatment agents. For a
technology to be effective, implementable, and economically
competitive; the treatment agents must be delivered in a
well-controlled manner. Conventional gravity- and pressure-
driven methods are available to deliver and recover fluids.
Gravity-driven methods rely on infiltration and collection due
to hydraulic gradients. Typically delivery is by surface
distribution and collection is by trench or similar drains.
Pressure-driven methods rely on pressure gradients sup-
plied by a source pump, a blower or steam generator, or an
extraction pump or blower. A system of wells typically is
used for delivery and recovery. The conventional delivery
and recovery systems are highly dependent on the physico-
chemical environment in the subsurface.
Innovative approaches are being developed and tested to
improve the performance of delivery and recovery
technologies in low-conductivity or heterogeneous geologic
settings. The innovative delivery and recovery technologies
may be devised to increase the conductivity in the treatment
zone, decrease the conductivity below the treatment zone,
or improve the efficiency of contact between the treatment
agents and the material to be treated. Conductivity .modifi-
cation technologies include hydraulic fracturing, pneumatic
fracturing, radial well drilling, jet slurrying, and kerfing.
Technologies to improve the distribution or application
efficiency of treatment agents include colloidal gas bubble
(aphron) generation, ultrasonic methods, and cyclic pumping
or steaming (U.S. EPA, 1990, EPA/540/2-90/002, p. 96).
Auger-mixing technologies have been developed to
deliver treatment agents with less reliance on a favorable
existing geology. Auger mixing is applicable to delivery but
not to recovery of treatment agents. The main examples of
auger delivery are steam injection and addition and mixing
of solidification/stabilization binders with augers. One ven-
dor is testing auger mixing for addition of bioremediation
nutrients.
Technologies to apply energy rather than fluids also are
available for in situ treatment. Energy delivery systems
reduce dependence on in situ conductivity but are sensitive
to other in situ parameters. The key to energy delivery is
good coupling of the electric or electromagnetic field to the
soil being heated. The electric properties change as the
moisture content changes. The energy input processes
vaporize water so the electrical coupling properties of the
soil must change as treatment proceeds. The changing soil
properties increase the challenge in designing an efficient
energy application system.
Systems for pneumatic fracturing and hydraulic fracturing
to improve subsurface conductivity and a system to inject
oxygen microbubbles to remediate groundwater have been
accepted in the SITE Program. The demonstration of a
pneumatic fracturing system was completed at a site located
in South Plainfield, New Jersey (Mack and Aspan, 1993, p.
321). The Applications Analysis Report is in preparation
(U.S. EPA, 1992, EPA/540/R-92/077, p. 5).
For further information on delivery and recovery technol-
ogies, contact:
Michael Roulier (513) 569-7796
or
Wendy Davis-Hoover (513) 569-7206
U.S. Environmental Protection Agency
Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
3.2 In Situ Solidification/Stabilization
In situ solidification/stabilization refers to treatment
processes that mix or inject treatment agents into the
contaminated material in place to accomplish one or more of
the following objectives:
• Improve the physical characteristics of the waste by
producing a solid from liquid or semiliquid wastes
• Reduce the contaminant solubility
• Decrease the exposed surface area across which
mass transfer of contaminants may occur.
In situ S/S relies on the delivery and effective mixing of
binders with the contaminated soil. The critical factors
applicable for in situ solidification/stabilization with inorganic
binders such as cementitious materials (cements and pozzo-
lans), silicates, or lime are shown in Table 3-1.
Treatment of Soils In Situ
11
-------
Table 3-1. Solidification/Stabilization Critical Factors and Conditions for Cement-Based Treatment Systems'"1
Factor Influencing
Technology Selection
Presence of VOCsC)
Contaminant
depth (*)
Specific gravity,
viscosity, and
general mixing
properties (*)
SVOC content of
waste (')
Oil and grease content
of waste 0
Leachability data (')
Phenol content
Fine particle
Soluble inorganic salts
(e.g., chlorides) not tar-
geted by binder
formulation
Cyanide content of the
waste
Sulfate content of the
waste
Binder heat of
hydration
Conditions Favoring Selection
of In Situ Treatment
<50ppb(1)(2)
Varies with technology (1)
No action levels
specified (1)(3)
SVOCs<10,OOOppm(4)
No action levels
specified (1)
No action levels
specified (2)
<5% (5)
Limited amount of fine insoluble
paniculate (4)
No action levels
specified (1)
<3,000 mg/kg (4)
<1,500 ppm for Type I Portland
cement (6)
Various cement types can toler-
ate higher sulfate levels but no
action level specified (6)(3)
No action levels
specified (5)
Basis
• VOCs can vaporize during processing or curing;
therefore, low levels of VOCs are favorable
• Organic materials can interfere with bonding
• In-place mixing with conventional construction type
equipment is limited to near surface
• Auger systems demonstrated to 30 feet
• Grout injection depth typically is not a major limitation
• Good mixing is needed to ensure contact of the waste
and binder so a good S/S product is obtained
• Organic materials can interfere with bonding
• SVOCs can vaporize during processing or curing;
therefore, tow levels of volatile compounds are favorable
(due to heat evolution in some processes, the favorable
limit can be much lower for some contaminants and S/S
binder combinations)
• Oil and grease can coat the waste particles inhibiting
setting or reducing the strength of the final product
• Mobile and soluble materials are more difficult to treat
• Phenol concentration greater than 5% can reduce the
compressive strength of the final product
• Rne particulates can coat the waste particles and
weaken the bond between the waste solids and cement
• Low concentrations are more favorable
• Threshold effects commonly occur
• Above some concentration levels, soluble salts can
reduce the physical strength of the final product cause
large variations in setting time, or reduce the
dimensional stability of the cured matrix
• Cyanides interfere with bonding of waste materials
• Presence of sulfates can retard setting
• High sulfate levels in waste can cause treated waste to
spall during curing due to formation of expansive
hydrates
• Large amount of heat generated by binder hydration
reactions, particularly in large mass treatment, can
increase temperature and volatilize organic
contaminants
OatiNMds
• Analysis for VOCs
• Treatability tests measuring
volatile emissions
• Waste composition and spatial
distribution
• Waste-specific gravity
• Waste panicle morphology and
size distribution
• Waste viscosity
• Analysis for SVOCs and PAHs
• Treatability tests measuring
volatile emissions
• Analysis for oil and grease
• Leachability testing
• Phenol content in waste
• Particle-size analysis, particularly
size fraction under 200 mesh
• Treatability testing
• Analysis of inorganic content
•Analysis for cyanides
• Analysis for sulfate
• Total and time-dependent heat
output due to hydration of binder
• Treatability tests measuring
volatile emissions
(a) Also see Table 2-3 for generic factors.
(*) Indicates higher-priority factors.
(1) Conner, 1990, pp. 189,205, and 464-477.
(2) U.S. EPA, 1993, EPA/530/R-93/012, pp. 4-51 and A-8.
(3) U.S. EPA, 1990, EPA/540/2-90/002, pp. 14-16.
(4) U.S. EPA, 1988, EPA/540/2-88/004, p. 93.
(5) U.S. EPA, 1991, EPA 540/2-91/009, p. 3.
(6) Amiella and Blythe, 1990, p. 93.
12
Treatment of Soils In SHu
-------
The most common binders are Portland cement, pozzo-
lans (siliceous or aluminous materials that can react with
calcium hydroxide to form compounds with cementitious
properties), and cement/pozzolan mixtures. Inorganic binder
systems using sodium silicate, cement/silicate, or proprietary
binder systems also are in use. Solidification/stabilization
encompasses a wide variety of physical and chemical mech-
anisms to reduce contaminant mobility and/or impart other
desirable properties to the waste. S/S treatment using
inorganic binders ties up free water by hydration reactions.
Mobility of inorganic compounds can be reduced by forma-
tion of insoluble hydroxides, carbonates, or silicates; sub-
stitution of the metal into a mineral structure; sorption;
physical encapsulation; and other mechanisms.
S/S treatment of organic contaminants with cementitious
formulations is more complex than treatment of inorganic
contaminants. Wastes where organics are the primary
contaminant of concern generally are not suited to S/S
treatment because of the potential for volatilization of organ-
ics and reduced S/S product quality when organics are
present. This is particularly true with VOCs where the
mixing process and heat generated by cement hydration
reactions can increase organic vapor losses. However, S/S
can be applied to wastes that contain lower levels of organ-
ics (particularly when inorganics are present at high
concentrations) and/or the organics have a low vapor pres-
sure, high water solubility, or both. Furthermore, recent
studies have indicated that addition of silicates or modified
clays to the binder system may improve S/S performance
wtth organics (U.S. EPA, 1993, EPA/530/R-93/012, pp. 4-12
and 4-13).
The most significant challenge in applying S/S in situ for
contaminated soils is achieving complete and uniform mixing
of the binder with the contaminated matrix (U.S. EPA, 1990,
EPA/540/2-90/002, p. 12). Three basic approaches are
used for mixing the binder with the matrix:
• Vertical auger mixing
• In-place mixing
• Injection grouting.
In vertical auger mixing, a system of augers is used to
inject and mix binder into the soil. Auger-type mixing sys-
tems developed by Novaterra (formerly Toxic Treatments
USA); International Waste Technologies (IWT)/Geo-Con,
Inc.; and S.M.W. Seiko, Inc. have been accepted in the
Superfund Innovative Technology Evaluation (SITE) Demon-
stration Program. SITE demonstrations have been complet-
ed for the Novaterra (U.S. EPA, 1991, EPA/540/A5-90/008)
and IWT systems (U.S. EPA, 1990, EPA/540/A5-89/004).
The treatment depth is limited by the length of available
auger equipment. Current testing indicates a limit of about
30 feet. Based on the SITE Program test of in situ S/S
using the IWT/Gec-Con auger system, estimated treatment
costs were $111/ton and $194/ton for 4-auger and 1-auger
systems, respectively. The costs included equipment,
startup and fixed costs, labor, supplies, utilities, analytical,
facility modification, and demobilization (U.S. EPA, 1990,
EPA/540/A5-89/004, p. 26). Note that some of the auger
systems, particularly the Novaterra system, may inject
steam (or steam and hot air) instead of binders to perform
steam stripping of organics. These operations are discus-
sed in Section 3.9.
In-place mixing involves spreading and mixing of binder
reagents with waste by conventional earth-moving equip-
ment such as draglines, backhoes, or clamshell buckets.
The technology is applicable only to surface or shallow
deposits of contamination.
The reported cost of in-place mixing is SSS/yd3. The cost
includes labor, equipment, monitoring and testing, reagents,
and miscellaneous supplies. Not included are costs for
equipment mobilization and demobilization, engineering and
administration, and health and safety (Amiella and Blythe,
1990, p. 101).
For injection grouting, a binder containing dissolved or
suspended treatment agents is forced into the formation
under pressure and allowed to permeate the soil. Grout
injection can be applied to contaminated formations lying
well below the ground surface. The injected grout then
cures in place to give an in situ treated mass. Grout injec-
tion is widely used for soil stabilization. A grouting system
for very fluid wastes developed by Hazardous Waste Control
has been accepted for testing in the SITE Program (U.S.
EPA. 1992, EPA/540/R-92/077, p. 100).
For further information on in situ solidification/
stabilization technologies, contact:
Patricia Erickson (513) 569-7884
U.S. Environmental Protection Agency
Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
3.3 Soil Vapor Extraction
In situ soil vapor extraction (SVE) is the process of
removing VOCs from the unsaturated zone to the surface
for treatment. Blowers attached to extraction wells alone or
in combination with air injection wells induce airflow through
the soil matrix. The airflow strips the volatile compounds
from the soil and carries them to extraction wells. The
process is driven by partitioning of volatile materials from
condensed phases (sorbed on soil particles, dissolved in
pore water, or nonaqueous liquid phases) to the clean air
being introduced by the vacuum extraction process. Air
emissions from the systems typically are controlled ex situ
by adsorption of the volatiles onto activated carbon, thermal
destruction (i.e., incineration or catalytic oxidation), or con-
densation by refrigeration (U.S. EPA, 1991, EPA/540/2-
91/006, p. 3). Application of soil vapor extraction relies on
the ability to deliver, control the flow, and recover stripping
air. A decision logic for treatability testing based on contam-
inant vapor pressure and air permeability of the soil has
been described in the literature (U.S. EPA, 1992,
EPA/600/K-92/003, pp. 4-8 and 4-9).
The critical factors to consider during review of SVE
technology application are presented in Table 3-2. The SVE
Treatment of Soils In Situ
13
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Table 3-2. Soil Vapor Extraction Critical Factors and Conditions'4
Factor Influencing
Technology Selection
Contaminant vapor pres-
sure. PVH
Air conductivity of soil (•)
Soil moisture content (*)
Clay content of soil (*)
Humic content in soil (')
Soil sorption capacity (*)
Contaminant water
solubility (*)
Henry's law constant (*)
Dominant contaminant
phase
Soil temperature
Depth to groundwater
Conditions Favoring Selection
of In Situ Treatment
Pv >0.5 mmHg at 20°C
(Reference describes decision
logic) (1)
>10-* cm/sec (2)
(Decision logic described) (1)
<10 volume % (2)
No action levels specified (1)
No action levels specified (3)
Specific surface area
<0.1 mz/g (2)
<100 mg/L (2)
>0.001 dimensionless (4)
Contaminant present as a sep-
arate phase (vapor or liquid) and
not sorted to the soil (2)
>20°C(2)
Contaminant in the unsaturated
zone(2)(5)
Basis
• Contaminants of higher volatility are more easily
removed by air stripping
• High conductivity results in a large radius of
influence for extraction wells
• Soil moisture inhibits airflow and can reduce
vapor pressure of soluble organics
• Low day content is desirable
• Presence of day increases sorption and inhibits
volatilization
• Low humic content is desirable
• Presence of humic materials increases sorption
and inhibits volatilization
• Contaminants held by sorption mechanisms are
more difficult to remove
• Dissolved organics are more difficult to remove
by air stripping
• Compounds that partition to the vapor phase are
more easily removed by stripping
• Vapors are more easily removed by air stripping
• Higher soil temperatures are more favorable to
volatilization
• Technology only effective in the unsaturated
zone
• Need to avoid water intrusion into extraction
wells
Data Needs
• Contaminant vapor pressure at
expected soil temperature
• Hydrogeotogic flow regime
• Soil moisture content
• Soil composition
• Soil color
• Soil texture
• Soil composition
• Soil color
• Soil texture
• Soil-specific surface area
• Sot! absorption isotherms
• Contaminant solubility at expected
soi temperature
• Henry's law constant
• Contaminant composition and
physical form
• Soil temperature
• Depth to groundwater
• Seasonal variation of groundwater
conditions
(a) Also see Table 2-3 for generic factors.
0 Indicates higher-priority factors.
(1) U.S. EPA, 1992. EPA/600/K-92/003, pp. 4-8 and 4-9.
(2) U.S. EPA, 1990. EPA/600/2-90/011, p. 40.
(3) U.S. EPA, 1988. EPA/540/2-88/004, p. 89.
(4) U.S. EPA, 1992. EPA/540/R-92/077, p. 175.
(5) U.S. EPA, 1991. EPA/540/2-91/003, p. 52.
technology has been used in commercial operations for
several years. It has been chosen as a component of the
ROOs at more than 80 Superfund sites (U.S. EPA, 1992,
EPA 542/R/92-011, pp. 31-46).
Vertical wells are the most widely used SVE design
method. Vertical wells are best used at sites where the
contamination extends far below the land surface. Horizon-
tal wells or trenches may be more practical than vertical
wells where the depth to groundwater is less than 12 feet
Vertical wells generally are inappropriate for sites with a
shallow water table due to the potential upwelling of the
water table that may occur after application of a high vacu-
um (U.S. EPA, 1991, EPA/540/2-91/003, p. 52).
SVE systems have been accepted in the SITE Program
(U.S. EPA, 1992, EPA/540/R-92/077). SITE demonstrations
of soil vapor extraction systems were completed at a Super-
fund site in Burbank, California (U.S. EPA, 1991, EPA/540/-
A5-91/002) and a Superfund site in Groveland, Massachu-
setts (U.S. EPA, 1989, EPA/540/A5-89/003). A reference
handbook on soil vapor extraction (U.S. EPA, 1991, EPA/5-
40/2-91/003) and screening computer software for an ap-
proach to the design, operation, and monitoring of SVE
systems are available (U.S. EPA, 1993, EPA/600/R-93/028).
Based on available data, SVE treatment cost estimates
typically are $50/ton for treatment of soil. The reported
estimates of cost ranges are $15 to $60/yd3 (U.S. EPA,
1990, EPA/60072-90/011, p. 40) and $27 to $66/ton (U.S.
EPA, 1989, EPA/540/A5-89/003, p. 11). The cost ranges
14
Treatment of Soils In Situ
-------
include consideration of site preparation; equipment pur-
chase, installation, and operation; residual well cuttings
disposal; analysis; and demobilization. The high end of the
range includes off-gas treatment, whereas the lower cost
does not. Off-gas treatment can amount to more than 50%
of the total cost of an SVE system (U.S. EPA, 1990, 937.5-
06/FS, p. 3-141).
For further information on soil vapor extraction technolo-
gies, contact
Michael Gruenfeld (908) 321-6625
U.S. Environmental Protection Agency
Risk Reduction Engineering Laboratory
Building #10 (MS 104)
2890 Woodbridge Avenue
Edison, NJ 08837-3679
3.4 In Situ Bioremediation
In biological processes, microorganisms degrade organic
compounds either directly to obtain carbon and/or energy, or
fortuitously in a cometabolic process with no significant
benefit to the microorganism. The ultimate goal of in situ
bioremediation is to convert organic contaminants into
btomass and innocuous by-products of microbial metabolism
such as carbon dioxide, inorganic salts, and water. Suc-
cessful in situ bioremediation can occur only if microbial
populations are present that can be stimulated to degrade
the contaminants of concern. In situ bioremediation capital-
izes on natural biological processes to enhance in situ
degradation of organic contaminants. Although biodegrada-
tion of organic contaminants occurs naturally in situ, often a
critical factor, such as oxygen, is limiting, thus limiting the
amount of biodegradation that can occur.
To increase the amount of biodegradation that occurs, in
situ amendments often are necessary. These amendments
may include electron acceptors (such as oxygen), carbon
sources, moisture, nutrients, or heat. The critical factors to
consider during review of in situ bioremediation applications
are presented in Table 3-3.
Bacteria, actinomycetes, and fungi in the subsurface
make up the most significant group of organisms involved in
biodegradation. These communities are diverse and adap-
table, capable of taking advantage of xenobiotic compounds.
Microbial populations at older sites generally are acclimated
to the contaminants of concern. Consequently, lack of
biodegradation in situ rarely is due to lack of populations
able to degrade the compounds, but more likely is due to
environmental conditions that limit the extent and rate of
biodegradation. Typically the most important parameters
are electron acceptor availability, moisture levels, tempera-
ture, pH, and nutrients.
Another critical parameter affecting the extent of in situ
bioremediation is bioavailability of the contaminant(s) of
concern. Bioavailability is a general term to describe the
accessibility of contaminants to the degrading populations.
Bioavailability consists of (1) a physical aspect related to
phase distribution and mass transfer, and (2) a physiological
aspect related to the suitability of the contaminant as a sub-
strate (U.S. EPA, 1993, EPA/540/S-93/501, p. 4). Com-
pounds with greater aqueous solubilities and lower affinity to
sorb onto the soil generally are more bioavailable to soil
microorganisms and are more readily degraded. Bioavail-
ability also depends on the suitability of the compound as a
metabolic substrate or cosubstrate.
Aerobic (>0.2 mg/L oxygen) or anaerobic conditions may
predominate in the subsurface. Mineralization of many
organic compounds occurs aerobically; therefore, aerobic
bioremediation is the most developed and most feasible in
situ biotechnology. In situ bioremediation under aerobic
conditions involves delivering oxygen and nutrients to the
subsurface through an injection well or infiltration system.
The oxygen and nutrients enhance the activity of indigenous
aerobic microorganisms that degrade the contaminants of
concern. In general, aerobic processes can be suitable for
remediation of petroleum hydrocarbons, halogenated and
nonhalogenated aromatics, polyaromatic hydrocarbons,
halogenated and nonhalogenated phenols, biphenyls,
organophosphates, and some pesticides and herbicides.
Biodegradation rates are compound specific, so treatability
judgments should be based on literature data for the con-
taminants present or on treatability tests.
Although mineralization of many compounds occurs
aerobically, some halogenated hydrocarbons may be
transformed under anaerobic conditions. These halogenat-
ed hydrocarbons include unsaturated alkyl halides (e.g.,
PCE and TCE) and saturated alkyl halides (e.g., 1,1,1-
trichloroethane and trihalomethane). In addition, supplying
nitrate as an electron acceptor under anaerobic conditions
may allow biodegradation of some phenols, cresols, and
lower-molecular-weight polycyclic aromatic hydrocarbons
(PAHs).
Anaerobic bioremediation is at a much earlier stage of
development than aerobic bioremediation. Establishing and
maintaining anaerobic conditions in situ is more difficult than
establishing and maintaining aerobic conditions. Anaerobic
treatment systems can have undesirable secondary effects
such as formation of volatile forms of metals (such as meth-
ylated mercury or arsines), toxic "deadend" intermediates
such as vinyl chloride and hydrogen sulfide, or nuisance
odor compounds.
Addition of amendments to promote in situ biodegrada-
tion generally relies on the ability of aqueous solutions to
infiltrate into the contaminated area. Aqueous-supplied
amendments have met with limited success, as the electron
acceptor or nutrient often is metabolized before it reaches
the contaminated area. Consequently, there is a high level
of microbial activity near or in the infiltration wells, often
resulting in plugging and poor flow.
In extreme environments, moisture or heat addition may
significantly improve bioremediation processes. Surface
insulation, warm water infiltration, and buried heat tape have
been used to increase the soil temperature. Their use has
Treatment of Soils In Situ
15
-------
Table 3-3. Bloremediation Critical Factors and Conditions'"
Factor Influencing
Technology Selection
Spatial variation of
waste composition or
concentration (*)
Contaminant
biodegradability (*)
Oxygen content (*)
Available soil water (*)
Presence of elevated
levels of metals, highly
chlorinated organics, pes-
ticides and herbicides, or
inorganic salts (*)
In situ temperature
Soil nutrient content
Water solubility
PH
Redox potential
Organic carbon content
Conditions Favoring Selection of
In Situ Treatment
No action levels specified (1)
Ratio of biological oxygen demand
(BOO) to chemical oxygen demand
(COO) >0.1 (3)
Aerobic metabolism: dissolved 02
>0.2 mg/L (4)
Air-filled pore space of >10% (4)
Anaerobic metabolism: gas-phase
02 concentration <1% (4)
>25% and <85% of water-holding
capacity (4)
No action levels specified (1)
>10°C (3)
Optimum temperature typically
20°C to 40°C (5)
Carbon/nitrogen/phosphorus ratios
about 100:10:1 (4)
Carbon/sulfur ratio noted as
important but no action level
specified (1)
>1, 000 mg/L (2)
Between 5-9 pH units (5)
Aerobes and facultative anaer-
obes: >50 millivolts (mV) (4)
Anaerobes: <50 mV (4)
Total organic carbon (TOC) of
groundwater between 10 and
1000 mg/L (3)
Basis
• Homogeneous conditions are desirable
• Large variation in the contaminant concentration
causes variation in biological activity giving
inconsistent biodegradation
• Resistance to biological action inhfcits
decontamination
• Oxygen depletion slows aerobic biological activity
• Oxygen is toxic to anaerobic systems
• High moisture content reduces bacterial activity by
limiting the transport of oxygen
• Low moisture content inhibits bacterial activity
• Materials can be toxic to microorganisms
• Lower levels are desirable
• Threshold effects commonly occur
• Optimum temperature range increases growth rate
• More diverse microbial populations are present in
optimum range
• Lack of adequate nutrients slows biological activity
• Contaminants with low solubility generally are more
difficult to degrade
• Toxic contaminants with high solubility, however, may
be more effective in suppressing broactivity
• When pH is outside of range, biological activity is
inhibited
• Reflects oxygen availability in the soil
• Indicates the oxidation/reduction potential of the
matrix
• Low concentrations may cause organisms to favor
other food; high concentrations may be toxic to the
organisms
Data Needs
• Waste composition and spatial
distribution
• Waste composition
• Waste BOD and COD
• Presence of metals or salts
• Treatability testing
• Oxygen monitoring
• Percent water saturation of
pores
• Identification of specific com-
pound, oxidation state (metals),
and concentration
• Temperature history and/or
monitoring covering at least
three seasons
• Carbon/nitrogen/
phosphorus ratio
• Form of nitrogen (e.g., nitrate,
ammonia, organic nitrogen)
• Carbon/sulfur ratio
• Contaminant solubility in water
at treatment temperature
• Soil pH
• Soil redox potential
•TOC
(a) Also see Table 2-3 for generic factors.
(*) Indicates higher-priority factors.
(1) U.S. EPA, 1988, EPA/540/2-88/004, p. 114.
(2) U.S. EPA, 1990. EPA/600/2-90/011, p. 48.
(3) U.S. EPA, 1990, EPA/600/2-90/027, p. 85.
(4) U.S. EPA, 1993, EPA/540/S-93/501, p. 3.
(5) U.S. EPA, 1990, EPA/540/2-90/002, pp. 40 and 47.
Treatment of Soils In Situ
-------
resulted in increased microbial activity and contaminant
degradation (Leeson et al., 1993).
The reported costs for application of in situ bioremedia-
tion range from $14 to $98Aon (U.S. EPA and U.S. Air
Force, 1993, p. 60). The EPA Vendor Information System
For Innovative Treatment Technologies (VISITT), Version 2,
contains information from 11 vendors on in situ soil biorem-
ediation technologies. The costs indicated by the vendors
typically range from $8 to $250/yd3 (U.S. EPA, 1993, EPA/
542/R-93-001).
A variety of in situ bioremediation systems have been
accepted in the SITE Program. Technologies include the
use of naturally occurring microorganisms, addition of cul-
tured bacteria, and addition of white-rot fungi. Water and
nutrients generally are applied by well injection or infiltration.
However, one technology assembles a containment tank in
situ to form a controlled area for the bioremediation, and
one technology uses vertical augers to distribute organisms
and nutrients. All of the technologies stimulate aerobic
biodegradation, except one, which combines anaerobic and
aerobic microbial activity (U.S. EPA, 1992, EPA/540/R-
92/077. p. 208).
For further information on bioremediation technologies,
contact
Carl Potter (513) 569-7231
U.S. Environmental Protection Agency
Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
3.5 Bioventing
Bioventing is the process of aerating subsurface soils to
stimulate in situ biological activity and promote bioremedia-
tion. Although bioventing is related to SVE, their primary
objectives are different. SVE is designed and operated to
maximize the volatilization of low-molecular-weight com-
pounds, with some biodegradation occurring. In contrast,
bioventing is designed to maximize biodegradation of aerobi-
cally biodegradable compounds, regardless of their molecu-
lar weight, with some volatilization occurring. Although both
technologies involve venting of air through the subsurface,
the differences in objectives result in different design and
operation of the remedial systems. Bioventing uses lower
air flow.
Bioventing normally is applied to certain types of organ-
ics, particularly petroleum hydrocarbons. It generally is not
considered useful for treating compounds such as PCBs
and chlorinated hydrocarbons.
The critical factors to consider during review of biovent-
ing are presented in Table 3-4. The significant features of
this technology include optimizing airflow to reduce volatil-
ization while maintaining aerobic conditions for biodegra-
dation; monitoring local soil gas conditions to ensure aerobic
conditions, not just monitoring vent gas composition; adding
moisture and nutrients as required to increase biodegra-
dation rates at some sites; and manipulating the water table
(dewatering) as required to ensure air/contaminant contact.
The in situ respiration test is useful as a rapid screening test
of the applicability of bioventing (Hinchee and Ong, 1992, p.
1305).
Table 3-4. Bioventing Critical Factors and Conditions*"
Factor Influencing
Technology Selection
Spatial variation of
waste composition or
concentration (')
Initial soil gas
concentrations (*)
Soil permeability (*)
Presence of elevated
levels of metals, highly
chlorinated organics,
pesticides and herbi-
cides, or inorganic
salts n
pH
Conditions Favoring Selection of
In Situ Treatment
No action levels specified (1 )
Initial soil gas concentrations of 02
(<5%), C02 (>10%), and total petro-
leum hydrocarbons (-10,000 pom) (2)
Soil air permeabilities >0.1 darcy (2)
No action levels specified (1)
Between 5-9 pH units (3)
Basis
• Homogeneous conditions are desirable
• Large variation in the contaminant concentration causes varia-
tion in biological activity giving inconsistent biodegradation
• These concentrations suggest high microbial activity due to
hydrocarbon degradation and generally indicate that bioventing
is feasible
• Low soil permeabilities restrict airflow through the soil,
decreasing the amount of air that can be provided for microbial
activity
• Lower levels are desirable
• Threshold effects commonly occur
• Materials can be toxic to microorganisms
• When pH is outside of range, biological activity is inhibited
Data Needs
• Waste composition
and spatial
distribution
• Soil gas monitoring
• Soil air permeability
testing
• Waste composition
> Soil pH
(a) Also see Table 2-3 for generic factors.
(*) Indicates higher-priority factors.
(1) U.S. EPA, 1988, EPA/540/2-88/004, p. 114.
(2) Hinchee et al., 1992.
(3) U.S. EPA, 1990, EPA/540/2-90/002, pp. 40 and 47.
Treatment of Soils In Situ
17
-------
Understanding the distribution of contaminants is impor-
tant to any in situ remediation process. Much of the hydro-
carbon residue at a fuel-contaminated site is found in the
unsaturated zone soils, in the capillary fringe, and immedi-
ately below the water table. Seasonal water table fluctua-
tions typically spread residues in the area immediately
above and below the water table. Any successful bioreme-
diation effort must treat these areas. Bioventing provides
oxygen to unsaturated zone soils and can be extended
below the water table when integrated with a dewatering
system.
Currently, conventional enhanced bioreclamation pro-
cesses use water to carry oxygen or an alternative electron
acceptor to the contaminated zone. This is common wheth-
er the contamination is present in the groundwater or in the
unsaturated zone. In most cases where water is used as
the oxygen carrier, the oxygen solubility is the limiting factor
for biodegradation. If pure oxygen is used and 40 mg/L of
dissolved oxygen is achieved, approximately 80,000 Ib of
water must be delivered to the formation to degrade 1 Ib of
hydrocarbon. If 500 mg/L of hydrogen peroxide is success-
fully delivered, then approximately 13,000 Ib of water must
be used to degrade the same amount of hydrocarbon. As a
result, even if hydrogen peroxide can be successfully used,
substantial volumes of water must be pumped through the
contaminated formation to deliver sufficient oxygen.
The use of an air-based oxygen supply for enhancing
biodegradation relies on airflow through contaminated soils
at rates and configurations that will both ensure adequate
oxygenation for aerobic biodegradation and minimize or
eliminate the production of a hydrocarbon-contaminated off-
gas. The addition of nutrients and moisture may be desir-
able to increase biodegradation rates; however, field re-
search to date does not indicate the need for these addi-
tions (Dupont et al., 1991; Miller et al., 1991). A key feature
of bioventing is the use of narrowly screened soil gas moni-
toring points to sample gas in short vertical sections of the
soil. These points are required to monitor local oxygen
concentrations, because oxygen levels in the vent well are
not representative of local conditions.
Bioventing systems can be configured in either injection
or extraction mode, or a combination of the two to push or
pull air through the vadose zone. A system using only air
injection has the advantage of not creating a point source
emission. This technology relies on the ability to move air
through the contaminated soil. Low-permeability soils are
more difficult to treat with bioventing.
Bioventing was accepted in the SITE Program in June
1991. Treatability tests were performed at the Reilly Tar
site in St. Louis Park, Minnesota, and the site was found to
be suitable for a test of the effectiveness of bioventing in
treating PAHs. A single-vent system was installed and will
be operated for a 3-year test period (Alleman, 1993). The
U.S. EPA has completed one field study of bioventing and is
conducting several others (Sayles, 1993).
The reported range of costs for applying bioventing is
$60 to $90/ton (U.S. EPA and U.S. Air Force, 1993, p. 61).
tact:
For further information on bioventing technologies, con-
Gregory Sayles (513) 569-7607
U.S. Environmental Protection Agency
Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
3.6 In Situ Vitrification
In situ vitrification is a thermal treatment process that
converts contaminated soils to stable glass and crystalline
solids. It originally was developed to stabilize transuranic
contaminated wastes and is being extended to treatment of
other hazardous wastes. For in situ vitrification processes,
high voltage is applied via electrodes placed in the soil to
induce current flow. The current heats the soil to melt-
formation temperature. Heating destroys or vaporizes
organic contaminants. After heating stops, the melt cools to
form a stable solid material. Application of in situ vitrification
requires conduction of electricity through the media to be
treated.
One application of the technology is based on electric
melter technology, and the principle of operation is joule
heating, which occurs when an electrical current is passed
through a molten mass. Reid application requires insertion
of electrodes into contaminated soils to supply the current
flow. Because unmelted soil is not conductive, a starter
path of flaked graphite and frit is placed between the elec-
trodes to act as the initial flowpath for electricity. Resis-
tance heating in the starter path creates a melt to carry
more current. The melt grows outward and downward from
the starter path (U.S. EPA, 1990, EPA/540/2-90/002, p. 17).
The melt can grow to encompass a volume of 1000 tons.
The maximum treatment depth is about 20 feet with possible
extension to 30 feet as the technology develops. Large
areas are treated in overlapping blocks.
Critical factors to consider during review of in situ vitrifi-
cation technology application are presented in Table 3-5.
The electric current flow heats soil to temperatures as
high as 1370°C (U.S. EPA, 1991, EPA 540/2-91/009, p. 7).
If the silica content of the soil is high enough, contaminated
soil is converted into durable glass. The combustible
wastes are pyrolyzed and other contaminants are incorpo-
rated into the vitreous mass. Off-gases released during the
melting process are trapped in an off-gas hood.
The main requirement for the technology is the ability for
the soil melt to carry current during heating and then solidify
to a stable mass as it cools. Wet soils can be treated by in
situ vitrification, but highly permeable soils and the presence
of groundwater increase operating costs. If the soil moisture
is recharged by groundwater, the electrical input needed to
vaporize the water increases costs. Buried combustibles or
containers such as tanks and drums introduce the possibility
of explosion.
18
Treatment of Soils In Situ
-------
The reported typical treatment rate is 3 to 5 tons per
hour (U.S. EPA, 1991, EPA 540/2-91/009, p. 7). In situ
vitrification is reported to provide above average long-term
effectiveness and permanence, and reductions in toxicity,
mobility, and volume.
In situ vitrification has been tested on a large scale ten
times, including two demonstrations on transuranic-
contaminated (radioactive) sites: (1) at Geosafe's test site,
and (2) at the U.S. Department of Energy's (DOE's) Hanford
Nuclear Reservation. More than 130 tests at various scales
have been performed on a broad range of waste types in
soils and sludges. The technology has been selected as a
preferred remedy at several private, EPA Superfund, and
DOE sites but has not been implemented in full-scale appli-
cation. In situ vitrification has been selected for the SITE
Program (U.S. EPA, 1992, EPA/540/R-92/077, p. 97). Tests
are being performed at the Parsons/ETM site in Grand
Ledge, Michigan.
There have been no full-scale applications to serve as a
basis for cost estimation. A DOE life-cycle cost analysis
suggests the overall cost of in situ vitrification would be
approximately $790Aon (U.S. EPA and U.S. Air Force, 1993,
p. 63). A commercial vendor of the technology indicates an
estimated cost range of $300 to $400/ton (Hansen and
FitzPatrick, 1991).
For further information on in situ vitrification technologies,
contact:
Ten Richardson (513) 569-7949
U.S. Environmental Protection Agency
Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
Table 3-5. In Situ Vitrification Critical Factors and Conditions^
Factor influencing
Technology Selection
Soil composition (*)
Contaminant
depth 0
Organic liquid content of
contaminated material (*)
Presence of in situ
voids (•)
Conductive metal
content (*)
Presence of sealed
containers (')
Presence of combustible
solids
Presence of
groundwater
Surface slope
Location of
structures
Conditions Favoring Selection of
In Situ Treatment
>30% Si02
>1.4% Na204KjO
on dry weight basis (1)
>6ftand
<20ft(1)
<1 to 7% organic content depending on
the BTU content of the organic (1)
Individual void volume <150 ft3 (1)(2)
<5% to 15% of total melt weight and
continuous conductive path <90% of
distance between electrodes (1)(2)
None present (1)
<3,200 kg combustible solids per meter of
depth or average concentration <30% in
the soil to be treated (1)
Groundwater control required if contami-
nation is below the water table and soil
hydraulic conductivity is >10~4cm/sec (1)
20 ft from melt zone (1)
Basis
• Required to form melt and cool to stable
treated waste form
• Overburden assists in capture of volatile
metals
• Deep contamination requires surface excava-
tion to allow placement of electrodes
• Can generate excessive hot off-gas on
combustion
• Can generate excessive off-gas
• Can cause excessive subsidence
• Can create a conductive path resulting in
uneven current flow and uneven heating
• Containers can rupture during heating
resulting in a large pulse of off-gas generation
• Can generate excessive off-gas volumes on
combustion
• Water inflow increases energy required to
vaporize water
• Melt may flow under influence of gravity
• Items closer than 20 ft to the melt zone must
be protected from heat
Otta Needs
• Weight loss on ignition
• Soil mineral composition as
oxides (x-ray fluorescence)
• Contaminant composition and
distribution
• Contaminant composition
• Heat of combustion of organic
materials
• Subsurface geology
• Subsurface matrix conditions
• Contaminant composition and
distribution
• Contaminant composition and
distribution
• Contaminant distribution
• Location of water table
• Seasonal variation of
groundwater conditions
• Site surface slope
• Contaminant composition and
distribution
• Subsurface conditions
(a) Also see Table 2-3 for generic factors.
(*) Indicates higher-priority factors.
(1) Pacific Northwest Laboratory, 1993.
(2) U.S. EPA, 1991, EPA 540/2-91/009, p. 3.
Treatment of Soils In Situ
19
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3.7 In Situ Radiofrequency Heating
Radiofrequency heating is a technique for rapid and
uniform heating of large volumes of soil in situ. This tech-
nique heats the soil to the point where volatile and semi-
volatile contaminants are vaporized into the soil pore space.
Vented electrodes are then used to recover the gases
formed in the pores during the heating process. The ex-
tracted gases can be incinerated or subjected to other
treatment methods. Application of radiofrequency heating
relies on efficient electromagnetic coupling of the radiofre-
quency source and the media being heated.
Radiofrequency heating is accomplished by use of
electromagnetic energy in the radiofrequency band. The
heating process does not rely on the thermal conductivity of
the soil. The energy is introduced into the soil matrix by
electrodes inserted into drilled holes. The mechanism of
heat generation is similar to that of a microwave oven. A
modified radio transmitter serves as the power source, and
the industrial, scientific, and medical band provides the
frequency at which the modified transmitter operates. The
exact operational frequency is obtained from an evaluation
of the areal extent of the contamination and the dielectric
properties of the soil matrix.
The critical factors to consider during review of radiofre-
quency heating technology application are presented in
Table 3-6. Full implementation of a radiofrequency heating
system at a contaminated hazardous waste site requires
four major subsystems.
• A radiofrequency energy depositions array
• Radiofrequency power-generating, transmitting, moni-
toring, and control systems
• A gas and liquid condensate handling and treatment
system
• A vapor containment and collection system.
Radiofrequency heating originally was developed and
tested for recovery of heavy oil. Three treatabil'rty tests of
radiofrequency heating on contaminated soils have been
performed. The first test was conducted at Volk Air National
Guard Base, Camp Douglas, Wisconsin. The treated vol-
ume was 500 ft3 heated to a depth of 7 feet. The contami-
nants were in a fire training area where waste oils, fuels,
and other hydrocarbons had been placed and ignited to
simulate aircraft fires (U.S. Air Force, 1989, p. 1). The
second test, performed at Rocky Mountain Arsenal, heated
a 1600-ft3 volume to a depth of 13 feet to treat organo-
chlorine pesticides and organophosphorus compounds (U.S.
Table 3-6. Radiofrequency Heating Critical Factors and Conditions'*'
Factor Influencing Tech-
nology Selection
Moisture content (')
Contaminant boiling point (*)
Conductive metal content (*)
Soil dielectric
constant
Soil loss tangent
Conditions Favoring Selec-
tion of In Situ
Treatment
No action level
specified (1)
Boiling point below 300°C (2)
No action level specified (3)
No action level specified (1)
No action level specified (1)
Basis
• A low moisture content is desirable
• High moisture content increases cost due to energy
needed to vaporize water
• Radiofrequency (RF) energy absorption properties
(dielectric constant and loss tangent) change as soil
dries, complicating design and operation of the RF
energy supply system
• Approximate economic limit of radiofrequency heating
• Metals strongly absorb RF energy, creating uneven
heating
• Dielectric material is needed to couple with
radiofrequency fields for energy transfer
• Change of properties with changing moisture content
is more important than actual magnitude of the
dielectric constant
• Dielectric material is needed to couple with
radiofrequency fields for energy transfer
• Change of properties with changing moisture content
is more important than actual magnitude of the loss
tangent
Data Needs
Soil moisture content
Contaminant boiling point or
vapor pressure as a function of
temperature
Subsurface matrix composition
Dielectric constant as a
function of moisture content
Loss tangent as a function of
moisture content
(a) Also see Table 2-3 for generic factors.
(*} Indicates higher-priority factors.
(l)Srestyetal., 1986, p. 88.
(2) U.S. EPA, 1990, EPA/540/2-90/002, p. 83.
(3) Just and Stockwell, 1993, p. 248.
20
Treatm0nt of Soils In Situ
-------
Army, 1992, p. 2-1). A demonstration of a phased-atray
radiofrequency antenna system to heat vadose zone clay
deposits contaminated with chlorinated hydrocarbons was
completed at the DOE Savannah River Laboratory (Kase-
vich et al., 1993, p. 23). Two radiofrequency heating tech-
nologies have been accepted in the SITE Program. The
demonstrations are being conducted at Kelly Air Force
Base, Texas and are scheduled for completion in 1994 (U.S.
EPA, 1992, EPA/540/R-92/077, p. 109).
The vendor indicates that the approximate cost range for
application of radiofrequency heating is $30 to $100/ton of
soil treated, depending on the moisture content (5% to 20%)
and the treatment temperature (100°C to 250CC) (U.S. EPA,
1989, EPA/600/S2-89/008, p. 2)(Sresty et al., 1992, p. 363).
For further information on radiofrequency heating tech-
nologies, contact:
Janet Houthoofd (513) 569-7524
U.S. Environmental Protection Agency
Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
3.8 Soil Flushing
Soil flushing is a process whereby the zone of contami-
nation is flooded with an appropriate washing solution to re-
move the contaminant from the soil. Water or an aqueous
solution is injected into or sprayed onto the area of contami-
nation. The contaminants are mobilized by solubilization,
formation of emulsions, or a chemical reaction with the
flushing solutions. After passing through the contamination
zone, the contaminant-bearing fluid is collected by strategi-
cally placed wells and brought to the surface for disposal,
recircuiation, or on-site treatment and reinjection. Applica-
tion of soil washing relies on the ability to deliver, control the
flow, and recover the flushing fluid.
The critical factors to consider during review of soil
flushing technology application are shown in Table 3-7. Soil
flushing requires the identification of a flushing solution that
is available in sufficient quantity at a reasonable cost
Flushing solutions may be water; acidic aqueous solu-
tions (such as sulfuric, hydrochloric, nitric, phosphoric, or
carbonic acids); basic solutions (such as sodium hydroxide);
chelating or complexing agents; reducing agents; or surfac-
tants. Water will extract water-soluble or water-mobile
constituents. Acidic solutions can be used to remove metals
or basic organic materials. Basic solutions may be used for
some metals such as zinc, tin, or lead and some phenols.
Chelating, complexing, and reducing agents may be needed
to recover some metals. Surfactants can assist in emulsifi-
cation of hydrophobia organics (U.S. EPA, 1991, EPA/540/2-
91/021, p. 2).
Soil flushing to remove organic materials has been
demonstrated at both bench and pilot scale. Several sys-
tems are in operation and many systems are being de-
signed for remediation of Superfund sites. Studies have
been conducted to determine the appropriate solvents for
mobilizing various classes and types of chemical constitu-
ents. Most of the applications involve remediation of VOCs
(U.S. EPA, 1992, EPA/542/R-92/011, pp. 26-29).
The soil flushing technology may be easy or difficult to
apply, depending on the ability to flood the soil with the
flushing solution and to install collection wells or subsurface
drains to recover all the applied liquids. Provisions also
must be made for ultimate disposal of the elutriate. The
achievable level of treatment varies and depends on the
contact of the flushing solution with the contaminants, the
appropriateness of the solutions for the contaminants, and
the hydraulic conductivity of the soil. The technology is
more applicable to permeable soils.
Water can be used to flush water-soluble or water-mobile
organics and inorganics. Hydrophilic organics are readily
solubilized in water. Organics amenable to water flushing
can be identified according to their soil/water partition coeffi-
cients or estimated from their octanol/water partition coeffi-
cients. Organics considered generally amenable to soil
flushing with water or water and surfactants are those with
an octanol/water partition coefficient (K^) of less than about
1000. High-solubility organics (e.g., lower-molecular-weight
alcohols, phenols, and carboxylic acids) and other organics
with a coefficient less than 10 may already have been
flushed from the site by natural processes. Medium solubili-
ty organics (K^. = 10 to 1000) that can be effectively re-
moved from soils by water flushing include low- to medium-
molecular-weight ketones, aldehydes, and aromatics and
lower-molecular-weight halogenated hydrocarbons, such as
TCE and tetrachloroethylene (PCE) (U.S. EPA, 1990, EPA/-
600/2-90/011, p. 50).
Soil flushing for inorganic treatment is less well devel-
oped than soil flushing for organics. Some applications at
Superfund sites have been reported, however. One system
is operational at a landfill with mixed organics and metals,
and another is operational at a chromium-contaminated site
(U.S. EPA, 1992, EPA/542/R-92/011, pp. 27 and 29).
Several other inorganic treatment systems are in the de-
sign or predesign phases at Superfund sites. Inorganics
that can be flushed from soil with water are soluble salts
such as the carbonates of nickel, zinc, and copper. Ad-
justing the pH with dilute solutions of acids or bases will
enhance inorganic solubilization and removal.
Removal of inorganic contaminants by soil flushing
typically requires injection and recovery of a chemical leach-
ing solution. The leaching solution must be selected to
remove the contaminant while not harming the in situ envi-
ronment Selection of the leaching solution also may be
limited by Land Disposal Restrictions or Underground Injec-
tion Control regulations.
Estimated costs for application of soil flushing range from
$75 to $200/yd3, depending on the waste quantity. These
are rough estimates and are not based on field studies (U.S.
EPA and U.S. Air Force, 1993, p. 56).
Treatment of Soils In Situ
21
-------
Table 3-7. Soil Flushing Critical Factors and Conditions'"
Factor Influencing
Technology Selection
Equilibrium partitioning of
contaminant between soil
and extraction fluid (')
Complex waste mixture (*)
Soil-specific surface area (*)
Contaminant solubility in
water (•)
Octanol/water partitioning
coefficient (')
'Spatial variation in waste
composition (')
Hydraulic conductivity (•)
Clay content (*)
Cation exchange
capacity (*)
PH(')
Buffering capacity (*)
Rushing fluid
characteristics (*)
Soil total organic carbon
content
Contaminant vapor pressure
Fluid viscosity
Organic contaminant density
Conditions Favoring
Selection of In Situ
Treatment
No action levels specified (1)
No action levels specified (1)
<0.1 rtAg (2)
>1,OOOmg/L(2)
Between 10 and 1000 (2)
No action levels specified (1)
>10^ cm/sec
No action levels specified (3)
No action levels specified (3)
No action levels specified (3)
No action levels specified (3)
Fluid should have low toxic-
ity, low cost, and allow for
treatment and reuse (1)
Fluid should not plug or have
other adverse effects on the
soil(1)
<1 wt% (2)
<10 mmHg (2)
<2 centipoise (cP) (2)
>2g/cm3{2)
Basis
• Contaminant preference to partition to the extractant is
desirable
• High partitioning of contaminant into the extraction fluid
decreases fluid volumes
• Complex mixtures increase difficulty in formulation of a
suitable extraction fluid
• High surface area increases sorption on soil
• Soluble compounds can be removed by water flushing
• Very soluble compounds tend to be removed by natu-
ral processes
• More hydrophilic compounds are amenable to removal
by water-based flushing fluids
• Changes in waste composition may require
reformulation of extraction fluid
• Good conductivity allows efficient delivery of flushing
fluid
• Low day content is desirable
• Presence of clay increases sorption and inhibits
contaminant removal
• Low cation exchange capacity is desirable
• Cation exchange capacity increases sorption and
inhibits contaminant removal
• May affect treatment additives required, compatibility
with materials of construction, or flushing fluid
formulation
• Indicates matrix resistance to pH change
• Toxicity increases health risks and increases regulatory
compliance costs
• Expensive or nonreusable fluid increases costs
• If the fluid adheres to the soil or causes precipitate
formation, conductivity may drop, making continued
treatment difficult
• Soil flushing typically is more effective with lower soil
organic concentrations
• Volatile compounds tend to partition to the vapor phase
• Lower-viscosity fluids flow through the soil more easily
• Dense insoluble organic fluids can be displaced and
collected by soil flushing
Data Needs
• Equilibrium partitioning
coefficient
• Contaminant composition
• Specific surface area of soil
• Contaminant solubility
• Octanol/water partitioning
coefficient
• Statistical sampling of
contaminated volume
• Hydrogeotogfc flow regime
• Soil composition
• Soil color
• Soil texture
• Cation exchange capacity
•SoilpH
• Soil buffering capacity
• Ruid characterization
• Bench- and pilot-scale testing
• Total organic carbon content of
soil
• Contaminant vapor pressure at
operating temperature
• Ruid viscosity at operating
temperature
• Contaminant density at
operating temperature
(a) Also see Table 2-3 for generic factors.
(•) Indicates higher-priority factors.
(1) U.S. EPA, 1988, EPA/540/2-88/004, p. 79.
(2) U.S. EPA, 1990, EPA/600/2-90/011, p. 54.
(3) U.S. EPA, 1991, EPA/540/2-91/021, p. 3.
22
Treatment of Soils In Situ
-------
The Superfund site at Palmetto Wood, South Carolina,
cited costs of $3,710,000 (capital) and $300,000 (annual
operation and maintenance). These totals, on a unit basis,
equal $185/yd3 for capital costs and $15/yd3 per year for
operation and maintenance (U.S. EPA, 1990, EPA/600/2-
90/01 1, p. 53).
For further information on soil flushing technologies,
contact:
Michael Qruenfeld (908) 321-6625
U.S. Environmental Protection Agency
Risk Reduction Engineering Laboratory
Building #10 (MS 104)
2890 Woodbridge Avenue
Edison, NJ 08837-3679
3.9 Steam/Hot Air Infection
and Extraction
In situ steam injection/extraction removes volatile and
semivolatlle hazardous contaminants from soil and ground-
water without requiring excavation. Steam injection may be
supplemented by hot air injection. In a few experimental
studies, hot air or hot combustion off-gas has been injected
to strip organics from in situ soil without steam (Smith and
Hinchee, 1993, p. 156). Waste constituents are removed
from the soil by this technology but are not actually treated.
Steam enhances the stripping of volatile contaminants from
soil and can be used to displace contaminated groundwater
under some conditions.
Steam extraction is effective for compounds with lower
vapor pressures than those remediated with ambient-tem-
perature SVE systems. By increasing the temperature from
initial conditions to the steam temperature, the vapor pres-
sure of the contaminants increases, causing them to be
more volatile. Steam is injected to form a displacement
front by steam condensation to displace groundwater. The
contaminated liquid and steam condensate are then col-
lected for further treatment and/or recycling to the steam
generator.
Mobilized nonaqueous-phase liquid and groundwater also
may be collected for treatment and disposal. Application of
steam/hot air injection and extraction relies on the ability to
deliver, control the flow, and recover the heating fluid.
The critical factors to consider during review of steam/hot
air injection and extraction technology application are
presented in Table 3-8.
A limited number of commercial-scale in situ steam
injection/extraction systems currently are in operation in the
United States, but in situ steam injection/extraction is a
rapidly developing technology. In situ steam injection/
extraction is being considered as a component of the reme-
dy for only one Superfund site, i.e., the San Fernando
Valley in California (Area 1) (U.S. EPA, 1991, EPA/540/2-
91/005, p. 6).
There are two main types of steam/hot air injection/-
extraction systems: a mobile system and a stationary
system. The mobile system consists of a unit that volatilizes
contaminants in small areas in a sequential manner by
injecting steam and hot air through rotating cutter blades
that pass through the contaminated medium. The stationary
system uses wells to inject steam into the soil to volatilize
and displace contaminants from the undisturbed subsurface.
Examples of both types of steam injection technologies have
been accepted in the SITE Program (U.S. EPA, 1992,
EPA/540/R-92/077).
For the mobile technology, the most significant factor
influencing cost is the treatment rate. Treatment rate is
determined primarily by the soil type (soils with higher clay
content require longer treatment times), the waste type, and
the on-line efficiency. An evaluation of a SITE demonstra-
tion indicated costs of $67 to $317/yd3 for treatment rates of
10 to 3 yd3/tir, respectively. These costs are based on a
70% on-line efficiency and include consideration of site
preparation; equipment purchase, installation, and operation;
and demobilization (U.S. EPA, 1991, EPA/540/A5-90/008, p.
21). Cost estimates for the general application of steam/hot
air injection fall in the range of $50 to $300/yd3 (U.S. EPA,
1991, EPA/540/2-91/005, p. 6).
Table 3-8. Steam/Hot Air Injection and Extraction Critical Factors and Conditions*1'
Factor Influencing
Technology Selection
Soil conductivity (*)
Humic content in soil (*)
Contaminant vapor
pressure (')
Conditions Favoring
Selection of In Situ
Treatment
No action levels specified (1)
No action levels specified (1)
Boiling point below 250°C (2)
Basis
• Low soil conductivity inhibits vapor flow
• Low humic content is desirable
• . Presence of humic materials increases sorption
and inhibits volatilization
• More volatile contaminants are more easily
removed by air stripping
Data Needs
• Hydrogeologic flow regime
• Soil composition
• Soil color
• Soil texture
• Contaminant boiling point or
vapor pressure as a function
of temperature
(a) Also see Table 2-3 tor generic factors.
(*) Indicates higher-priority factors.
(1) U.S. EPA, 1988, EPA/540/2-88/004, p. 89.
.(2) U.S. EPA, 1990, EPA/600/2-89/066, p. 51.
Treatment of Soils In Situ
23
-------
For further information on steam/hot air injection tech-
nologies, contact:
Michael Gruenfeld (908) 321-6625
U.S. Environmental Protection Agency
Risk Reduction Engineering Laboratory
Building #10 (MS 104)
2890 Woodbridge Avenue
Edison, NJ 08837-3679
4.0 Acknowledgments
This Engineering Issue Paper was developed for the U.S.
EPA Engineering Forum by the U.S. EPA Risk Reduction
Engineering Laboratory (RREL) through Contract No. 68-CO-
0003 with the Battelle Memorial Institute. Battelle provided
primary authorship and layout of the document, while many
other people contributed in a significant way by providing
direction, guidance, assistance, information, or review.
The EPA Technical Project Manager was Janet
Houthoofd. The Engineering Forum lead contacts were
Robert Stamnes, Region 10, and Paul Leonard, Region 3.
The Battelle Work Assignment Manager was Susan
Brauning, and the principal author was Lawrence Smith.
Other contributors or reviewers were Thomasine Bayless,
Joan Colson, Patricia Erickson, Chi-Yuan (Evan) Fan,
Michael Gruenfeld, Carl Potter, Ten Richardson, Michael
Roulier, Gregory Sayles, Laurel Staley, and Robert Stenburg
- EPA RREL; Linda Fiedler - EPA Technology Innovation
Office; John Matthews - EPA Robert S. Kerr Environmental
Research Laboratory; and Bruce Alleman, Lynn Copley-
Graves, Robert Hinchee, Andrea Leeson, and Thomas
Naymik - Battelle.
Acknowledgments are due also to the primary Engineer-
ing Forum Superfund Contacts shown in the box below.
EPA Engineering
Region 1
Region 2
Region 3
Region 4
Region 5
Region 6
Region 7
Region 8
Region 9
Region 10
Headquarters
Forum Superfund
Lynne Jennings
Chet Janowski
Richard Ho
Paul Leonard
Jon Bomholm
Anthony Holoska
Deborah Griswold
Steve Kinser
Desiree Golub
Ken Erickson
Bob Stamnes
Richard Steimle
Contacts
(617) 573-9634
(617) 573-9623
(212) 264-9543
(215) 597-3163
(404) 347-7791
(312) 886-7503
(214) 655-6730
(913) 551-7728
(303)293-1838
(415)744-2324
(206)553-1512
(703) 308-8846
5.0 References
s
Alleman, Bruce, 1993. Personal Communication. (614)
424-5715. Battelle Memorial Institute. Columbus, Ohio.
Amiella, Elio F. and Leslie J. Blythe, 1990. 'Solidifying
Traps Hazardous Wastes." Chemical Engineering.
97(2):92-102. February.
Conner, Jessie R., 1990. Chemical Fixation and Solidifica-
tion of Hazardous Wastes. Van Nostrand Reinhold.
New York, New York.
Donehey, Angela J., Reva A. Hyde, R.B. Piper, M.W. Roy,
and S.S. Walker, 1992. "In Situ Physical and Chemical
Treatments." In Proceedings of the 1992 U.S. EPA/
A&WMA International Symposium on In Situ Treatment
of Contaminated Soil and Water. Air & Waste Manage-
ment Association. Pittsburgh, Pennsylvania, pp. 98-106.
Dupont, R. Ryan, William J. Ooucette, and Robert E. Hin-
chee, 1991. "Assessment of In Situ Bioremediation
Potential and the Application of Bioventlng at a Fuel-
Contaminated Site." In Robert E. Hinchee and Robert F.
Olfenbuttel (Eds.), In Situ Bioraclamation: Applications
and Investigations for Hydrocarbon and Contaminated
Site Remediation, pp. 262-282. Butterworth-Heinemann.
Stoneham, Massachusetts.
Hansen, J.E. and V.F. FitzPatrick, 1991. In Situ Vitrification
Applications, Geosafe Corporation. Richland, Washing-
ton.
Hinchee, Robert E. and Say Kee Ong, 1992. 'A Rapid In
Situ Respiration Test for Measuring Aerobic Biodegra-
dation Rates of Hydrocarbons in Soil." Journal of the Air
& Waste Management Association. 42(10):1305-1312.
October.
Houthoofd, Janet M., John H. McCready, and Michael H.
Roulier, 1991. "Soil Heating Technologies for In Situ
Treatment: A Review." In Proceedings of the 17th Annu-
al Hazardous Waste Research Symposium. EPA/600/9-
91/002. Office of Research and Development, Risk Re-
duction Engineering Laboratory. Cincinnati, Ohio, pp.
190-203.
Just, Sharon R. and Kenneth J. Stockwell, 1993. "Com-
parison of the Effectiveness of Emerging In Situ Tech-
nologies and Traditional Ex Situ Treatment of Solvent-
Contaminated Soils." In ACS Symposium Series 518 -
Emerging Technologies in Hazardous Waste Manage-
ment. III. American Chemical Society. Washington, DC.
pp. 238-277.
Kasevich, Raymond, Raymond Holmes, David Faust, and
Richard Beleski, 1993. "Radio Frequency Heat Enhanc-
es Contaminant Removal." Soils, pp. 18-23. March.
Leeson, Andrea, Robert E. Hinchee, Jeffrey A. Kittel, Grego-
ry Sayles, Catherine Vogel, and Ross Miller, 1993.
"Optimizing Bioventing in Shallow Vadose Zones in Cold
Climates," Hydrological Sciences Journal. 38(4): in
press.
Mack, James P. and Howard N. Aspan, 1993. "Using
Pneumatic Fracturing Extraction to Achieve Regulatory
Compliance and Enhance VOC Removal from Low-
Permeability Formations." Remediation. 3(3):309-326.
Treatment of Soils In SHu
-------
Miller, Ross N., Catherine C. Vogel and Robert E. Hinchee,
1991. *A Field-Scale Investigation of Petroleum Hydro-
carbon Biodegradation in the Vadose Zone Enhanced by
Soil Venting at Tyndall AFB, Florida.' In Robert E. Hin-
chee and Robert F. Olfenbuttel (Eds.), In Situ Bioreclam-
ation: Applications and Investigations for Hydrocarbon
and Contaminated Site Remediation, pp. 283-302. But-
terworth-Heinemann. Stoneham, Massachusetts.
Pacific Northwest Laboratory, 1993. ReOpt Remediation
Technology Database. PNL Richland, Washington.
Sayles, Gregory D. 1993. Personal Communication. (513)
569-7607. U.S. Environmental Protection Agency.
Cincinnati, OH.
Smith, Lawrence A. and Robert E. Hinchee, 1993. In Situ
Thermal Technologies for Site Remediation. Lewis
Publishers. Ann Arbor, Michigan.
Sresty, Guggilam C., Harsh Dev, Richard H. Snow, and
Jack E. Bridges, 1986. 'Recovery of Bitumen From Tar
Sand Deposits With the Radio Frequency Process.'
SPE Reservoir Engineering, pp. 85-94. Society of Petro-
leum Engineers. January.
Sresty, Guggilam C., Harsh Dev, and Janet Houthoofd,
1992. "In Situ Decontamination by Radio Frequency
Heating." In Proceedings of the 1992 U.S. EPA/A&WMA
International Symposium on In Situ Treatment of Con-
taminated Soil and Water. Air & Waste Management
Association. Pittsburgh, Pennsylvania, pp. 356-364.
U.S. Air Force, 1989. In Situ Soil Decontamination by Ra-
dio-Frequency Heating - Field Test. ESL-TR-88-62. Air
Force Engineering & Services Center. Tyndall Air Force
Base, Florida.
U.S. Air Force, 1992. Test Plan and Technical Protocol for
a Field Treatability Test for Bioventing, Rev. 2. U.S. Air
Force Center for Environmental Excellence. Brooks Air
Force Base, Texas.
U.S. Army, 1992. Final Rocky Mountain Arsenal In Situ
Radio Frequency Heating/Vapor Extraction Pilot Test
Report, Vol. I, 5300-01-12-AAFP. Rocky Mountain Arse-
nal. Commerce City, Colorado.
U.S. Environmental Protection Agency, 1988. Guidance for
Conducting Remedial Investigations and Feasibility Stud-
ies under CERCLA - Interim Final. EPA/540/G-89/004.
Office of Emergency and Remedial Response. Washing-
ton, DC.
U.S. Environmental Protection Agency, 1988. Technology
Screening Guide for Treatment of CERCLA Soils and
Sludges. EPA/540/2-88/004. Office of Emergency and
Remedial Response. Washington, DC.
U.S. Environmental Protection Agency, 1989. Project Sum-
mary - Radiofrequency Enhanced Decontamination of
Soils Contaminated with Halogenated Hydrocarbons.
EPA/600/S2-89/008. Office of Research and Develop-
ment, Risk Reduction Engineering Laboratory. Cincin-
nati, Ohio.
U.S. Environmental Protection Agency, 1989. Terra Vac In
Situ Vacuum Extraction System - Applications Analysis
Report. EPA/540/A5-89/003. Office of Research and
Development, Risk Reduction Engineering Laboratory.
Cincinnati, Ohio.
U.S. Environmental Protection Agency, 1990. Assessing
UST Corrective Action Technologies: Early Screening of
Clean-up Technologies for the Saturated Zone. EPA/-
600/2-90/027. Office of Research and Development,
Risk Reduction Engineering Laboratory. Cincinnati,
Ohio.
U.S. Environmental Protection Agency, 1990. Assessing
UST Corrective Action Technologies: Site Assessment
and Selection of Unsaturated Zone Treatment Technol-
ogies. EPA/600/2-90/011. Office of Research and De-
velopment, Risk Reduction Engineering Laboratory. Cin-
cinnati, Ohio.
U.S. Environmental Protection Agency, 1990. Cost of
Remedial Action (CORA) Model - Version 3.0. 937.5-
06/FS. Office of Solid Waste and Emergency Response.
Washington, DC.
U.S. Environmental Protection Agency, 1990. Handbook on
In Situ Treatment of Hazardous Waste-Contaminated
Soils. EPA/540/2-90/002. Office of Research and De-
velopment, Risk Reduction Engineering Laboratory.
Cincinnati, Ohio.
U.S. Environmental Protection Agency, 1990. International
Waste Technologies Geo-Con In Situ Stabilization/-
Solidification - Applications Analysis Report EPA/5-
40/A5-89/004. Office of Research and Development,
Risk Reduction Engineering Laboratory. Cincinnati,
Ohio.
U.S. Environmental Protection Agency, 1990. Technologies
of Delivery or Recovery for the Remediation of Hazard-
ous Waste Sites. EPA/600/2-89/066. Office of Research
and Development, Risk Reduction Engineering Labora-
tory. Cincinnati, Ohio. (NTIS: PB90-156 225/AS)
U.S. Environmental Protection Agency, 1991. AWD Tech-
nologies Integrated AquaDetoxWSVE Technology -
Applications Analysis Report EPA/540/A5-91/002.
Office of Research and Development, Risk Reduction
Engineering Laboratory. Cincinnati, Ohio.
U.S. Environmental Protection Agency, 1991. Engineering
Bulletin - In Situ Soil Flushing. EPA/540/2-91/021.
Office of Emergency and Remedial Response. Wash-
ington, DC. and Office of Research and Development,
Risk Reduction Engineering Laboratory. Cincinnati, Ohio.
U.S. Environmental Protection Agency, 1991. Engineering
Bulletin - In Situ Soil Vapor Extraction Treatment. EPA/-
540/2-91/006. Office of Emergency and Remedial Re-
sponse. Washington, DC. and Office of Research and
Development, Risk Reduction Engineering Laboratory.
Cincinnati, Ohio.
U.S. Environmental Protection Agency, 1991. Engineering
Bulletin - In Situ Steam Extraction Treatment. EPA/-
540/2-91/005. Office of Emergency and Remedial Re-
sponse. Washington, DC. and Office of Research and
Development, Risk Reduction Engineering Laboratory.
Cincinnati, Ohio.
U.S. Environmental Protection Agency, 1991. Soil Vapor
Extraction Technology: Reference Handbook. EPA/540/-
2-91/003. Office of Research and Development, Risk
Reduction Engineering Laboratory. Cincinnati, Ohio.
Treatment of Soils In Situ
25
-------
U.S. Environmental Protection Agency, 1991. Superfund
Engineering Issue - Treatment of Lead-Contaminated
Soils. EPA/540/2-91/009. Office of Solid Waste and
Emergency Response. Washington, DC. and Office of
Research and Development, Risk Reduction Engineering
Laboratory. Cincinnati, Ohio.
U.S. Environmental Protection Agency, 1991. Toxic Treat-
ments, In Situ Steam/Hot Air Stripping Technology -
Applications Analysis Report. EPA/540/A5-90/008.
Office of Research and Development, Risk Reduction
Engineering Laboratory. Cincinnati, Ohio.
U.S. Environmental Protection Agency, 1992. Guide for
Conducting Treatability Studies under CERCLA, Final.
EPA/540/R-092/071a. Office of Research and Develop-
ment, Risk Reduction Engineering Laboratory, and Office
of Emergency and Remedial Response, Office of Solid
Waste and Emergency Response. Washington, DC.
U.S. Environmental Protection Agency, 1992. Innovative
Treatment Technologies: Semi-Annual Status Report, 4th
ed. EPA/542/R-92/011. Office of Solid Waste and
Emergency Response, Technology Innovation Office.
Washington, DC.
U.S. Environmental Protection Agency, 1992. Seminar on
the Use of Treatability Guidelines in Site Remediation.
EPA/600/K-92/003. Office of Research and Develop-
ment. Washington, DC.
U.S. Environmental Protection Agency, 1992. The Super-
fund Innovative Technology Evaluation Program - Tech-
nology Profiles, 5th ed. EPA/540/R-92/077. Office of
Research and Development, Risk Reduction Engineering
Laboratory. Cincinnati, Ohio.
U.S. Environmental Protection Agency, 1993. Decision-
Support Software for Soil Vapor Extraction Technology
Application: Hyperventilate. EPA/600/R-93/028. Office
of Research and Development. Risk Reduction Engi-
neering Laboratory. Cincinnati, Ohio.
U.S. Environmental Protection Agency, 1993. Engineering
Issue - In Situ Bioremediation of Contaminated Unsatu-
rated Subsurface Soils. EPA/540/S-93/501. Office of
Research and Development. Robert S. Kerr Environ-
mental Research Laboratory. Ada, Oklahoma, and
Office of Solid Waste and Emergency Response. Wash-
ington, DC.
U.S. Environmental Protection Agency, 1993. Technical
Resources Document on Solidification/Stabilization and
Its Application to Waste Materials. EPA/530/R-93/012.
Risk Reduction Engineering Laboratory. Cincinnati, Ohio.
U.S. Environmental Protection Agency, 1993. VISITT Ven-
dor Information System For Innovative Treatment Tech-
nologies. VISITT User Manual, Version 2. EPA/542/R-
93-001. Office of Solid Waste and Emergency Re-
sponse. Washington, DC.
U.S. Environmental Protection Agency and U.S. Air Force,
1993. Remediation Technologies Matrix Reference
Guide. Draft report. U.S. Environmental Protection
Agency, Technology Innovation Office, Washington, DC.
and U.S. Air Force, Armstrong Laboratory Environics
Directorate. Tyndall Air Force Base, Florida.
Treatment of Soils Ir
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Purpose
Section 121(b) of the Comprehensive Environment
Response, Compensation, and Liability Act (CERCLA) man-
dates the Environmental Protection Agency (EPA) to select
remedies that "utilize permanent solutions and alternative
technologies or resource recovery technologies to the maxi-
mum extent practicable" and to prefer remedial actions in
which treatment "permanently and significantly reduces
the volume, toxicity, or mobility of hazardous substances,
pollutants and contaminants as a principal element." The
Engineering Bulletins comprise a series of documents that
summarize the latest information available on selected
treatment and site remediation technologies and related
issues. They provide summaries of and references for the
latest information to help remedial project managers, on-
scene coordinators, contractors, and other site cleanup
managers understand the type of data and site characteris-
tics needed to evaluate a technology for potential applica-
bility to their Superfund or other hazardous waste site.
Those documents that describe individual treatment tech-
nologies focus on remedial investigation scoping needs.
Addenda will be issued periodically to update the original
bulletins.
Abstract
In situ biodegradation may be used to treat low-to-
intermediate concentrations of organic contaminants in-
place without disturbing or displacing the contaminated
media. Although this technology has been used to degrade
a limited number of inorganics, specifically cyanide and
nitrate, in situ biodegradation is not generally employed to
degrade inorganics or to treat media contaminated with
heavy metals.
During in situ biodegradation, electron acceptors (e.g.,
oxygen and nitrate), nutrients, and other amendments may
be introduced into the soil and groundwater to encourage
the growth of an indigenous population capable of degrad-
ing the contaminants of concern. These supplements are
used to control or modify site-specific conditions that
impede microbial activity and, thus, the rate and extent of
contaminant degradation. Depending on site-specific
cleanup goals, in situ biodegradation can be used as the
sole treatment technology or in conjunction with other
biological, chemical, and physical technologies in a treat-
ment train. In the past, in situ biodegradation has often
been used to enhance traditional pump and treat technolo-
gies by reducing the time needed to achieve aquifer cleanup
standards.
One of the advantages of employing an in situ technol-
ogy is that media transport and excavation requirements
are minimized, resulting in both reduced potential for
volatile releases and minimized material handling costs.
Biological technologies that require the physical displace-
ment of media during treatment (e.g., "land treatment"
applications involving excavation for treatment in lined
beds or tilling of non-excavated soils) assume many of the
risks and costs associated with ex situ technologies and
cannot strictly be considered in situ applications.
As of Fall 1993, in situ biodegradation was being
considered or implemented as a component of the remedy
at 21 Superfund sites and 38 Resource Conservation and
Recovery Act (RCRA), Underground Storage Tank (UST),
Toxic Substances Control Act (TSCA), and Federal sites with
soil, sludge, sediment, or groundwater contamination
[1, p. 13]'[2][3]. This bulletin provides information on
the technology's applicability, the types of residuals pro-
duced, the latest performance data, the site requirements,
the status of the technology, and sources for further
information.
Technology Applicability
In situ biodegradation has been shown to be poten-
tially effective at degrading or transforming a large number
of organic compounds to environmentally-acceptable or
less mobile compounds [4, p. S4][5, p. 103][6][7][8][9].
Soluble organic contaminants are particularly amenable to
biodegradation; however, relatively insoluble contaminants
may be degraded if they are accessible to microbial degrad-
* [reference number, page number]
Printed on 'Recycled Paper
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ers. Classes of compounds considered amenable to biodeg-
radation include petroleum hydrocarbons (e.g., gasoline
and diesel fuel), nonchlorinated solvents (e.g., acetone,
ketones, and alcohols), wood-treating wastes (e.g., creo-
sote and pentachlorophenol), some chlorinated aromatic
compounds (e.g., chlorobenzenesand biphenyls with fewer
than five chlorines per molecule), and some chlorinated
aliphatic compounds (e.g., trichloroethene and
dichloroethene). As advances in anaerobic biodegradation
continue, many compounds traditionally considered resis-
tant to aerobic biodegradation may eventually be de-
graded, either wholly or partially, under anaerobic condi-
tions. Although not normally used to treat inorganics (e.g.,
acids, bases, salts, heavy metals, etc.), in situ biodegrada-
tion has been used to treat water contaminated with ni-
trate, phosphate, and other inorganic compounds.
Although in situ biodegradation may be used to
remediate a specific site, this does not ensure that it will be
effective at all sites or that the treatment efficiency achieved
will be acceptable at other sites. The complex contaminant
mixtures found at many Superfund sites frequently result in
chemical interactions or inhibitory effects that limit con-
taminant biodegradabillty. Elevated concentrations of pes-
ticides, highly chlorinated organics, and some inorganic
salts have been known to inhibit microbial activity and thus
system performance during in situ biodegradation.
Treatability studies should be performed to determine the
effectiveness of a given in situ biological technology at each
site. Experts based out of EPA's Risk Reduction Engineering
Laboratory (RREL) in Cincinnati, Ohio and the Robert S. Ken-
Environmental Research Laboratory (RSKERL) in Ada, Okla-
homa may be able to provide useful guidance during the
treatability study and design phases. Other sources of
general observations and average removal efficiencies for
different treatability groups are contained in the Superfund
Land Disposal Restrictions (LOR) Guide #6A, "Obtaining a
Soil and Debris Treatability Variance for Remedial Actions,"
(OSWER Directive 9347.3-06FS, September 1990) [10] and
Superfund LDR Guide #66, "Obtaining a Soil and Debris
Treatability Variance for Removal Actions," (OSWER Direc-
tive 9347.3-06BFS, September 1990) [11].
Limitations
Site- and contaminant-specific factors impacting con-
taminant availability, microbial activity, and chemical reac-
tion rates may limit the application of in situ biodegrada-
tion. Variations in media composition and contaminant
concentrations can lead to variations in biological activity
and, ultimately, inconsistent degradation rates. Soil char-
acteristics (e.g., non-uniform particle size, soil type, mois-
ture content, hydraulic conductivity, and permeability) and
the amount, location, and extent of contamination can also
have a profound impact on bioremediation. The following
text expands upon these factors.
The biological availability, or bioavailability, of a con-
taminant is a function of the contaminant's solubility in
water and its tendency to sorb on the surface of the soil.
Contaminants with low solubility are less likely to be distrib-
uted in an aqueous phase and may be more difficult to
degrade biologically. Conversely, highly soluble com-
pounds may leach from the soil before being degraded. In
general, however, poor bioavailability can be attributed to
contaminant sorption on the soil rather than a low or high
contaminant solubility. The tendency of organic molecules
to sorb on the soil is determined by the physical and
chemical characteristics of the contaminant and soil. In
general, the leaching potential of a chemical is proportional
to the magnitude of its adsorption (partitioning) coefficient
in the soil. Hydrophobic (i.e., "water fearing") contami-
nants, in particular, routinely partition from the soil water
and concentrate in the soil organic matter, thus limiting
bioavailability. Additionally, contaminant weathering may
lead to binding in soil pores, which can limit availability
even of soluble compounds. Important contaminant prop-
erties that affect sorption include: chemical structure,
contaminant acidity or basicity (pKa or pKb), water solubil-
ity, permanent charge, polarity, and molecule size. In some
situations surfactants (e.g., "surface acting agents") may
be used to increase the bioavailability of "bound" or in-
soluble contaminants. However, it may be difficult to iden-
tify a surfactant that is both nontoxic and not a preferred
substrate for microbial growth.
Soil solids, which are comprised of organic and inor-
ganic components, may contain highly reactive charged
surfaces that play an important role in immobilizing organic
constituents, and thus limiting their bioavailability. Certain
types of inorganic clays, possess especially high negative
charges, thus exhibiting a high cation exchange capacity.
Alternatively, clays may also contain positively charged
surfaces, causing these particles to exhibit a high anion
exchange capacity. Soil organic matter also has many
highly reactive charged surfaces which can limit
bioavailability [12].
Bioavailability is also a function of the biodegradability
of the target chemical, i.e., whether it acts as a substrate,
co-substrate, or is recalcitrant. When the target chemical
cannot serve as a metabolic substrate (source of carbon and
energy) for microorganisms, but is oxidized in the presence
of a substrate already present or added to the subsurface,
the process is referred to as co-oxidation and the target
chemical is defined as the co-substrate [12][13, p.4]. Co-
metabolism occurs when an enzyme produced by an organ-
ism to degrade a substrate that supports microbial growth
also degrades another non-growth substrate that is neither
essential for nor sufficient to support microbial growth. Co-
oxidation processes are important for the biodegradation
of high molecular weight polycyclic aromatic hydrocarbons
(PAHs), and some chlorinated solvents, including
trichloroethene (TCE). However, like surfactants,
cometabolites (e.g., acetate and phenol) may be more
readily mineralized by the indigenous microorganisms than
the target organics [13, p. 4].
Microbial activity can be reduced by nutrient, mois-
ture, and oxygen deficiencies, significantly decreasing bio-
degradation rates. Extreme soil temperatures, soil alkalin-
ity, or soil acidity can limit the diversity of the microbial
population and may suppress specific contaminant degrad-
%IJLSite.B!odegradcrtion Treatment]
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era. Spatial variation of soil conditions (e.g., moisture,.
oxygen availability, pH, and nutrient levels) may result in
inconsistent biodegradation due to variations in biological
activity. While these conditions may be controlled to favor
biodegradation, the success of in situ biodegradation de-
pends in a large part on whether required supplements can
be delivered to areas where they are needed. Low hydraulic
conductivity can hinder the movement of water, nutrients,
aqueous-phase electron acceptors (e.g., hydrogen perox-
ide and nitrate), and, to a lesser extent, free oxygen through
the contamination zone [14, p. 155]. Restrictive layers
(e.g., clay lenses), although more resistant to contamina-
tion, are also more difficult to remediate due to poor
permeability and low rates of diffusion [13, p. 4]. Low
percolation rates may cause amendments to be assimilated
by soils immediately surrounding application points, pre-
venting them from reaching areas that are more remote,
either vertically or horizontally. During the simultaneous
addition of electron acceptors and donors through injec-
tion wells, excessive microbial growth or high iron or
manganese concentrations may cause clogging in the well
screen or in the soil pores near the well screen [15]. Variable
hydraulic conductivities in different soil strata within a
contaminated area can also complicate the design of flow
control; minor heterogeneities in lithology can, in some
cases, impede the transfer of supplements to specific sub-
surface locations.
Microbial activity may also be influenced by contami-
nant concentrations. Each contaminant has a range of
concentrations at which the potential for biodegradation is
maximized. Below this range microbial activity may not
occur without the addition of co-substrate. Above this
range microbiat activity may be inhibited and, once toxic
concentrations are reached, eventually arrested. During
inhibition, contaminant degradation generally occurs at a
reduced rate. In contrast, at toxic concentrations, contami-
nant degradation does not occur. The concentrations at
which microbial growth is either supported, inhibited, or
arrested vary with the contaminant, medium, and micro-
bial species. Given long-term exposure, microbes have
been known to acclimate to very high contaminant concen-
trations and other conditions inhibiting microbial activity.
However, if prompt treatment is a primary goal, as is the
case during most remedial activities, toxic conditions may
need to be addressed by pH control, metals control (e.g.,
immobilization), sequential treatment or by introducing
microbial strains resistant to toxicants.
Numerous biological and non-biological mechanisms
(e.g., volatilization, sorption, chemical degradation, migra-
tion, and photodecomposition) occur during biological
treatment. Since some amendments may react with the
soil, site geochemistry can limit both the form and concen-
tration of any supplements added to the soil. Thus, care
must be employed when using amendments to "enhance"
biological degradation. For example, ozone and hydrogen
peroxide, which can be added to enhance dissolved oxygen
levels in soil or groundwater systems, may react violently
with other compounds present in the soil, reduce the
sorptive capacity of the soil being treated, produce gas
bubbles that block the pores in the soil matrix, or damage
the bacterial population in the soil [4, p. 43]. Nitrogen and
phosphorus (phosphate) must also be applied cautiously to
avoid excessive nitrate formation [4, p.47] and the precipi-
tation of calcium and iron phosphates, respectively. Exces-
sive nitrate levels in the groundwater can cause health
problems in humans, especially children. If calcium con-
centrations are high, the added phosphate can be tied up
by the calcium and, therefore, may not be available to the
microorganisms [16, p. 23]. Lime treatment for soil pH
adjustment is dependent on several soil factors including
soil texture, type of clay, organic matter content, and
aluminum concentrations [4, p. 45]. Since changes in soil
pH may also affect the dissolution or precipitation of mate-
rials within the soil and may increase the mobility of
hazardous materials, pH amendments (acid or base) should
be added cautiously and should be based on the soil's
ability to resist changes in pH, otherwise known as the soil's
"buffering capacity" [4, p. 46]. Since the buffering capacity
varies between soils, lime and acidification requirements
should be determined on a site-specific basis.
Finally, high concentrations of metals can have a det-
rimental effect on the biological treatment of organic
contaminants in the same medium. A number of metals can
be oxidized, reduced, methylated (i.e., mercury), de-
methylated, or otherwise transformed by various organ-
isms to produce new contaminants. The solubility, volatil-
ity, and sorption potential of the original soil contaminants
can be greatly changed in the process [17, p. 144], leading
to potential significant lexicological effects, as is the case
during the methylation of mercury. To avoid these compli-
cations, it is sometimes possible to pretreat or complex the
metals into a less toxic or teachable form.
Technology Description
During in situ biodegradation, site-specific characteris-
tics are modified to encourage the growth of a microbial
population capable of biologically degrading the contami-
nants of concern. Presently, two major types of in situ
systems are being employed to biodegrade organic com-
pounds present in soils, sludges, sediments, and groundwa-
ter: bioventing systems and "traditional" in situ biodegra-
dation systems, which usually employ infiltration galleries/
wells and recovery wells to deliver required amendments to
the subsurface. In general, bioventing has been used to
treat contaminants present in the unsaturated zone. Tradi-
tional in situ biodegradation, on the other hand, has mostly
been used to treat saturated soils and groundwater. The
occasional treatment of unsaturated soil using traditional in
situ biodegradation techniques has been generally limited
to fairly shallow regions over groundwater that is already
contaminated.
Traditional In Situ Biodegradation
Traditional in situ biodegradation is generally used in
conjunction with groundwater-pumping and soil-flushing
systems to circulate nutrients and oxygen through a con-
taminated aquifer and associated soil. The process usually
Engineering Bulletin: In Situ Biodegradation Treatment
-------
involves introducing aerated, nutrient-enriched water into
the contaminated zone through a series of injection wells or
infiltration trenches and recovering the water down-gradi-
ent. Depending upon local regulations and engineering
concerns, the recovered water can then be treated and, if
necessary, reintroduced to the soil onsite, discharged to the
surface, or discharged to a publicly-owned treatment works
(POTW). A permit may be required for the re-injection of
treated water. Note that a variety of techniques can be used
to introduce and distribute amendments in the subsurface.
For example, a lower horizontal well is being used at the
Savannah River Site near Aiken, North Carolina to deliver air
and methane to the subsurface. A vacuum has been applied
to an upper well (in the vadose zone) located at this site to
encourage the distribution of air and methane within the
upper saturated zone and lower vadose zone [18][19].
Figure 1 is a general schematic of a traditional in situ
biodegradation system [20, p. 113][16, p. 13]. The first
step in the treatment process involves pretreating the
infiltration water, as needed, to remove metals (1). Treated
or contaminated groundwater, drinking water, or alterna-
tive water sources (e.g., trucked water) may be used as the
water source. If groundwater is used, iron dissolved in the
groundwater may bind phosphates needed for biological
growth. Excess phosphate may be added to the infiltration
water at this point in the treatment process in order to
complex the iron [20, p. 111 ]. The presence of iron will also
cause a more rapid depletion of hydrogen peroxide, which
is sometimes used as an oxygen source. Surface active
agents may also be added at this point in the treatment
process to increase the bioavailability of contaminants,
especially hydrophobic or sorbed pollutants, while meth-
ane or other substances may be added to induce the co-
metabolic biodegradation of certain contaminants. In
continuous recycle systems, toxic metals originally located
in the contaminated medium may have to be removed from
the recycled infiltration water to prevent inhibition of
bacterial growth. The exact type of pretreatment will vary
with the water source, contamination problem, and treat-
ment system used.
Following infiltration water pretreatment, a biological
inoculum can be added to the infiltration water to enhance
the natural microbiai population (2). A site-specific inocu-
lum enriched from site samples may be used; commercially
available cultures reported to degrade the contaminants of
concern can also be used (e.g., during the remediation of
"effectively sterile soils"). Project managers are cautioned
against employing microbiai supplements without first as-
sessing the relative advantages associated with their use
and potential competition that may occur between the
indigenous and introduced organisms. The ability of mi-
crobes to survive in a foreign and possibly hostile (I.e.,
toxic) environment, as well as the ability to metabolize a
wide range of substrates should be evaluated. The health
effects of commercial inocula must also be carefully evalu-
ated, since many products on the market are not carefully
screened or processed for pathogens. It is essential that
independently-reviewed data be examined before employ-
ing a commercially-marketed microbiai supplement [21].
Nutrient addition can then be employed to provide
nitrogen and phosphorus, two elements essential to the
biological activity of both indigenous and introduced or-
ganisms (3). Optimum nutrient conditions are site-specific.
Trace elements may be added at this stage, but are normally
available in adequate supply in the soil or groundwater.
During contaminant oxidation, energy is released as
electrons are removed. Since oxygen acts as the terminal
electron acceptor during aerobic biodegradation, oxygen
concentrations in the subsurface may become depleted. To
avoid this complication, air, oxygen, and other oxygen
Figure 1.
Schematic Diagram of Traditional In Situ Biodegradation of Soil and Croundwater
iEnalne^rin^Bullenn^triSltuBlodeQtQdaHonJreatmei^
-------
sources (hydrogen peroxide and ozone) can be added to
the infiltration water (4). To prevent gas binding in the
subsurface, and a subsequent reduction in the effective soil
permeability, oxygen amendment/supplementation meth-
ods must be carefully selected. During anaerobic degrada-
tion, alternative electron acceptors (nitrate, carbonate, or
sulfate) may be added to the infiltration water in place of
oxygen. Alternatively, during the co-oxidation of a target
substrate, a co-substrate (methanol or acetate) may be
added to the infiltration water [22].
just before the water is added to the soil or groundwa-
ter, chemical additives may be used to adjust the pH
(neutral is recommended for most systems) and other
parameters that impact biodegradation (5). Care should be
taken when making adjustments to the pH, since contami-
nant mobility (especially of metals) can be increased by
changing the pH [4, p. AS]. Site managers are also cau-
tioned against employing chemical additives that are per-
sistent in the environment The potential toxicity of addi-
tives and any synergistic effects on contaminant toxicity
should also be evaluated.
During in situ bioremediation, amendment concentra-
tions and application frequencies can be adjusted to com-
pensate for physical/chemical depletion and high microbial
demand. If these modifications fail to compensate for
microbial demand, remediation may occur by a sequential
deepening and widening of the active treatment layer (e.g.,
as the contaminant is degraded in areas near the amend-
ment addition points, and microbial activity decreases due
to the reduced substrate, the amendments move farther,
increasing microbial activity in those areas). Additionally,
hydraulic fracturing may be employed to improve amend-
ment circulation within the subsurface.
The importance of using a well-designed hydraulic
delivery system and thoroughly evaluating the compatibil-
ity of chemical supplements was demonstrated at sites in
Park City, Kansas; Kelly AFB, Texas; and Eglin AFB, Florida.
Air entrainment and iron precipitation resulted in a contin-
ued loss of injection capacity during treatment at the Park
City site [23][24] and calcium phosphate and iron precipi-
tation resulted in the failure of the two field tests at Kelly
and Eglin AFBs, respectively [25].
Biovontlng
Bioventing uses relatively low-flow soil aeration tech-
niques to enhance the biodegradation of soils contami-
nated with organic contaminants. Although bioventing is
predominantly used to treat unsaturated soils, applications
involving the remediation of saturated soils and groundwa-
ter (e.g., using air sparging techniques) are becoming more
common [26][27]. Aeration systems similar to those em-
ployed during soil vapor extraction are used to supply
oxygen to the soil (Figure 2). Typically a vacuum extrac-
tion, air injection, or combination vacuum extraction and
air injection system is employed [28]. An air pump, one or
more air injection or vacuum extraction probes, and emis-
sions monitors at the ground surface are commonly used.
Although some systems utilize higher air flow rates, thereby
combining bioventing with soil vapor extraction, low air
pressures and low air flow rates are generally used to
maximize vapor retention times in the soil while minimizing
contaminant volatilization. An interesting modification to
traditional aeration techniques has been proposed at the
Picatinny Arsenal in New jersey. Here researchers and
project managers have proposed collecting TCE vapors at
the surface, amending them with degradable hydrocar-
bons (methane, propane, or natural gas) capable of stimu-
lating the cometabolic degradation of vapor-phase TCE,
and then re-injecting the amended vapors into the unsatur-
ated zone in an attempt to encourage the in situ
bioremediation of the TCE remaining in the subsurface
[29][30][31][32][27].
Off-gas treatment (e.g., through biofiltration or car-
bon adsorption) will be needed during most bioventing
applications to ensure compliance with emission standards
and to control fugitive emissions. Off-gas treatment sys-
tems similar to those employed during soil vapor extraction
may be used. These systems must be capable of effectively
collecting and treating a vapor stream consisting of the
original contaminants and/or any volatile degradation prod-
ucts generated during treatment. Although similar vapor
treatment systems may be employed during soil vapor
extraction and bioventing, less concentrated off-gases would
be expected from a bioventing system than from a soil
vapor extraction system employed at the same site. This
difference in concentration is attributed to enhanced bio-
logical degradation within the subsurface.
Nutrient addition may be employed during bioventing
to enhance~~bibdegradation. Nutrient addition can be
accomplished by surface application, incorporation by till-
ing into surface soil, and transport to deeper layers through
applied irrigation water. However, in some field applica-
tions to date, nutrient additions have been found to provide
no additional benefits [33]. Increasing the soil temperature
may also enhance bioremediation, although in general
high temperatures should be avoided since they can de-
crease microbial population and activity. Heated air, heated
water, and low-level radio-frequency heating are some of
the techniques which can be used to modify soil tempera-
ture. Soil core analyses can be performed periodically to
assess system performance as determined by contaminant
removal. A control plot located near the bioventing system,
but not biovented, may also be used to obtain additional
information to assess system performance.
Process Residuals
During in situ biodegradation, limited but potentially
significant process residuals may be generated. Although
the majority of wastes requiring disposal are generated as
part of pre- and post-treatment activities, process residuals
directly arising from in situ biological activities may also be
generated. These process residuals may include: 1) par-
tially degraded metabolic by-products, 2) residual con-
tamination, 3) wastes produced during groundwater pre-
and post-treatment activities, and 4) volatile contaminants
that are either directly released into the atmosphere or
Engineering Bulletin: In Situ Biodegradation Treatment
-------
collected within add-on emission control\treatment sys-
tems. The following text expands upon the specific types
of process residuals, their control, and their impact on
disposal requirements.
Ultimately biological technologies seek to mineralize
hazardous contaminants into relatively innocuous by-prod-
ucts, specifically carbon dioxide, water, and inorganic salts.
However, a number of site- and contaminant-specific fac-
tors may cause the partial degradation or "biotransforma-
tion" of a contaminant and the generation of an intermedi-
ate by-product. These metabolic by-products may be
located in either the saturated or unsaturated zones. The
identity, toxicity, and mobility of these partially degraded
compounds should be determined since intermediate deg-
radation products can be as toxic or more toxic than the
parent compound. Since metabolic by-products can accu-
mulate in the soil and groundwater, future remedial actions
may be necessary.
In addition to intermediate degradation by-products,
residual contamination may persist in the soil following
treatment. Microbes are capable of degrading only that
fraction of the contamination that is readily available for
microbial incorporation. As a result, biologically resistant
contaminants and contaminants that remain sorbed to the
soil and sediment during the remedial action cannot be
degraded. Depending on the nature of the contaminants
and media, the "bound* fraction may slowly desorb over
long periods of times (months to years), potentially re-
contaminating "treated" media near the residual contami-
nation [34][35]. Additionally, fluctuations in the water
table may result in the recontamination of previously
remediated soils if groundwater contamination, specifically
contamination associated with the presence of a light non-
aqueous phase layer (LNAPL), has not been effectively
addressed.
Above-ground activities taken to ensure that the reme-
dial action complies with regulatory requirements and
adequately guards against cross-contamination and un-
controlled releases may result in the generation of a signifi-
cant volume of waste requiring disposal. For example,
when groundwater is used to deliver amendments to the
subsurface, it may be necessary to pre-treat the water
before it can be re-introduced to the subsurface. Addition-
ally, in order to protect water quality outside of the treat-
ment zone from contaminant or amendment migration, a
down-gradient groundwater recovery and treatment sys-
tem designed to collect and treat amendment- and con-
taminant-laden groundwater may be needed. The residu-
als produced by these add-on treatment processes will
eventually require disposal.
Significant volatile emissions may also be produced
during in situ biodegradation (e.g., bioventing). Depend-
ing on their concentration, toxicity, and total volume, these
emissions, which may consist of the original contaminant or
any volatile degradation products produced during treat-
ment, may need to be controlled, collected, or treated.
Ultimately, the by-products of an emissions treatment/
control system will require disposal.
Site Requirements
In situ biodegradation normally requires the installa-
tion of wells or infiltration trenches; therefore, adequate
Figure 2. Bioventing
Low rate
air injection
Surface monitoring
to ensure
no emissions
Air extraction
Air extraction
Biodegradation
of contaminat
soils
Monitonng of soil
gas to assess vapor
biodegradation
Biodegradation of vapors
-------
access roads are required for heavy equipment such as well-
drilling rigs and backhoes. Soil-bearing capacity, traction,
and soil stickiness can limit vehicular traffic [17, p. 61].
In general, the area required to set up mixing equip-
ment is not significant However, space requirements
increase as the complexity of the various pre- and post-
treatment systems increases. During the installation of
infiltration galleries and wells, several hundred up to several
thousand square feet of clear surface area will be required.
Climate can also influence site requirements. If periods of
heavy rainfall or extremely cold conditions are expected, a
cover may be required.
Electrical requirements will depend on the type of
technology employed. Standard 220V, three-phase electri-
cal service may be used to supply power to pumps and
mixing equipment. Since water is used for a variety of
purposes during biological treatment, a readily available
water supply will be needed at most sites. Municipal water
or clean groundwater may be used. Contaminated ground-
water may be used if permitted by the appropriate regula-
tory agency. The quantity of water needed is site- and
process-specific Waste storage is not normally required for
in situ biodegradation.
Onsite analytical equipment for conducting pH and
nutrient analyses will help improve operation efficiency and
provide better information for process control. During
bioventing applications, air emissions monitors at the ground
surface are commonly used.
Regulatory Considerations and
Response Actions
Federal mandates can have a significant impact on the
application of in situ biodegradation. RCRA LDRs that
require treatment of wastes to best demonstrated available
technology (BOAT) levels prior to land disposal may some-
times be determined to be applicable or relevant and
appropriate requirements (ARARs) for CERCLA response
actions. The in situ biodegradation technology can pro-
duce a treated waste that meets treatment levels set by
BDAT, but may not reach these treatment levels in all cases.
The ability to meet required treatment levels is dependent
upon the specific waste constituents and the waste matrix.
In cases where in situ biodegradation does not meet these
levels, it still may, in certain situations, be selected for use
at the site if a treatability variance establishing alternative
treatment levels is obtained. Treatability variances are
justified for handling complex soil and debris matrices. The
following guides describe when and how to seek a treatability
variance for soil and debris: Superfund LDR Guide #6A,
"Obtaining a Soil and Debris Treatability Variance for Reme-
dial Actions" (OSWER Directive 9347.06FS, September 1990)
[10], and Superfund LDR Guide #6B, "Obtaining a Soil and
Debris Treatability Variance for Removal Actions" (OSWER
Directive 9347.06BFS, September 1990) [11]. Another
approach could be to use other treatment techniques with
in situ biodegradation to obtain desired treatment levels,
for example) carbon treatment of recovered groundwater
prior to re-infiltration into the subsurface.
When determining performance relative to ARARs and
BDATs, emphasis should be placed on assessing the risk
presented by a bioremediation technology. As part of this
effort, risk assessment schemes, major metabolic pathways
of selected hazardous pollutants, human health protocols
for metabolite and pathogenicity tests, and fate protocols
and issues for microorganisms and metabolites must be
assessed [36]. A detailed summary of the findings of the
June 17-18, 1993 EPA/Environment Canada Workshop in
Duluth, Minnesota addressing Bioremediation Risk Assess-
ment should be available in early 1994.
Performance Data
Performance data for Superfund sites are limited. The
first record of decision (ROD) selecting in situ biodegrada-
tion as a component of the remedy was in FY87. Since then,
in situ biodegradation of soil or groundwater contaminants
has either been considered or selected at 22 Superfund sites
and 30 RCRA, UST, TSCA, and Federal sites [1][2][3]. The
following two subsections address traditional in situ and
bioventing applications, respectively; a third subsection
has been included to briefly address information sources
and data concerns related to remedial efforts performed in
the private sector.
Traditional In Situ Bioremediation
Methane and phenol were employed during a series of
stimulus-response studies investigating the co-metabolic
degradation of TCE, cis-dichloroethene (c-DCE), trans-
dichloroethene (t-DCE), and vinyl chloride (VC) at the
Moffet Field site in California. Both sets of experiments
used indigenous bacteria and were performed under the
induced gradient conditions of injection and extraction.
During the first set of experiments, methane, oxygen, and
TCE (from 50 to 100 u.g/L), c-DCE, t-DCE, and VC were
added to the soil to stimulate methanotrophic degradation
of the injected chlorinated aliphatic compounds. Approxi-
mately 20 percent of the TCE added to the system was
degraded within the 2-meter hydraulically-controlled
biostimulated zone. Approximately SO percent of the c-
DCE, 90 percent of the t-DCE, and 95 percent of the VC
were also degraded. During the second set of tests, meth-
ane was replaced with phenol in order to stimulate growth
of an indigenous phenol-utilizing population. During 4
weeks of testing, the concentration of TCE injected into the
subsurface was raised from an initial concentration of 62
Hg/L to a final concentration of 1000 iig/L. A bromide
tracer was used to determine transformation extent. Up to
90 percent of the TCE in the 2-meter biostimulated zone
was degraded, demonstrating that even at relatively high
TCE concentrations significant removal efficiencies can be
achieved in situ through phenol and dissolved oxygen (DO)
addition. During the course of the project, transformation
yields (i.e., grams of TCE per grams of phenol) ranging from
0.0044 to 0.062 were obtained for varying concentrations
Engineering Bulletin: In Situ Biodegradation Treatment
-------
of phenol and TCE. Future studies at the site will determine
whether a compound more environmentally acceptable
than methane or phenol can be used to induce an indig-
enous population that effectively degrades TCE [37][7][8).
A 40- by 120-foot test zone in an aquifer that receives
leachate from an industrial landfill at the Du Pont Plant near
Victoria, Texas was used to demonstrate the in situ biotrans-
formation of tetrachloroethene (PCE), TCE, DCE,
chloroethane, and VC to ethane and ethylene using micro-
bial reductive dehalogenation under sulfate-reducing con-
ditions. Croundwater from this zone was alternately
amended with either benzoate or sulfate and circulated
through the aquifer. Initially PCE and TCE concentrations
were approximately 10 and 1 micro-mole (u,M), respec-
tively. After a year of treatment the halogenated com-
pounds were reduced to concentrations near or below 0.1
liM. PCE and TCE degraded to DCE rapidly following the
introduction of benzoate. A decrease in sulfate concentra-
tions led to increases in the vinyl chloride concentrations.
Therefore, sulfate concentrations were kept above 10 mg/
L until the OCE was further biodegraded. After approxi-
mately 6 months of treatment, most of the DCE,
chloroethane, and VC biodegraded to produce ethane and
ethylene [38].
A field-scale in situ bioremediation system, consisting
of down-gradient groundwater extraction wells and an up-
gradient infiltration system, was installed at a gasoline-
contaminated site owned by the San Diego Gas and Electric
Company. [Note: extracted groundwater was amended
with nutrients (nitrate and phosphate) prior to re-infiltra-
tion into the subsurface]. Due to the relatively low rate of
groundwater extraction (approximately 800 to 900 gallons
per day) and the low hydraulic gradient at the site (0.004),
it took nearly 2 years (until June/July 1991) for the added
nitrate to reach the down-gradient well and overtake the
xylene (BTX) plume. BTX concentrations, which ranged
from 25 to 50 mg/L for the preceding 2-year period,
dropped markedly as nitrate levels in the groundwater
increased. By late August 1991, benzene and toluene
concentrations had dropped below the detection limit
(0.01 mg/L), and total xylene concentrations had dropped
to 0.02 mg/L. The coincident occurrence of nitrate appear-
ance and BTX loss in the aquifer, as well as an eight-fold
increase in the percentage of denitrifiers present in the
groundwater (from 1 to 8 percent), points to a potential
stimulatory effect nitrate may have on BTX loss in situ [5].
An in situ bioremediation system consisting of four
injection and three recovery wells was employed to treat
gasoline contamination present in the saturated zone at a
former service station in Southern California. During treat-
ment, recovered groundwater was amended with hydro-
gen peroxide (from 500 to 1,000 mg/L) and nutrients and
re-injected into the aquifer. Prior to treatment, total fuel
hydrocarbons in the saturated clay soils ranged from below
detection limits to 32 mg/kg as BTX. Maximum groundwa-
ter concentrations were 2,700 ug/L for benzene; 6,600 \igl
L for toluene; 4,100 ug/L for xylene; and 45,000 ug/L for
TPH [4]. After 10 months, BTX and TPH levels in the
groundwater and saturated soils had dropped below the
detection limits. Roughly 1,350 kilograms of hydrogen
peroxide were introduced to the aquifer over 10 months,
roughly two times the estimated requirements based on the
estimated mass of hydrocarbon in the saturated zone (i.e.,
110 kg of fuel hydrocarbon and 2 to 3 kg of dissolved
hydrocarbons). After 34 months of treatment, soil hydro-
carbon concentrations ranged from below the detection
limit to 321 ppm as TPH; benzene was not detected in any
samples [39].
Following successful laboratory treatability testing,
General Electric performed a 10V2-week field study to
investigate the biodegradation of polychlorinated biphe-
nyls (PCBs) in the Hudson River sediment. Initial PCB
concentrations in the sediment ranged between 20 and 40
ppm. The study attempted to enhance the aerobic bacteria
native to the upper Hudson River. Six caissons were
installed at the Hudson River Research Station (HRRS) to
isolate sections of the river bottom for this field study.
Because of extensive, naturally occurring dechlorination,
approximately 80 percent of the total PCBs encountered in
the sediments were mono-, di-, and trichlorobiphenyls.
Biodegradation was stimulated using oxygen and nutrient
addition. Mixing was employed to enhance the dispersal of
oxygen and nutrients within the sediment. Between 38 and
55 percent of the PCBs present in the sediment were
removed by aerobic degradation during the study.
This corresponds to the percentage biologically available
PCBs [9].
Bioventing
In May 1992, the U.S. Air Force began a Bioventing
Initiative to examine bioventing as a remedial technique at
contaminated sites across the country. The Air Force's
decision to examine bioventing on such a large scale was
prompted by a successful demonstration of the technology
at Tyndall AFB, Florida, where bioventing coupled with
moisture addition removed one-third of the TPH and nearly
all of the BTEX in |P-4 contaminated soils during 7 months
of treatment. The Bioventing Initiative targets 138 sites
with diesel fuel, jet fuel, or fuel oil in soil. In selecting sites
for the initiative, the Air Force looked for characteristics
appropriate for bioventing, such as deep vadose soil, heavy
hydrocarbon contamination, and high air permeability.
The chosen sites represent a wide range of depths to
groundwater, hydrocarbon concentrations, and soil tex-
tures. Preliminary testing has been completed and 33
systems have been installed at Battle Creek Air National
Guard Base and the following AFBs: Beale, Eglin, Eielson,
F.E. Warren, Galena, Hanscom, Hill, K.I. Sawyer, McGuire,
Newark, Offutt, Pittsburgh, Robins, Vandenberg, and
Westover. According to the Air Force, initial results are very
promising with degradation rates measured as high as
5,000 mg/kg per year [40][41].
The EPA RREL, in collaboration with the U.S. Air Force,
initiated two 3-year pilot-scale bioventing field studies in
mid-1991 at )P-4 contaminated fuel sites located at Eielson
AFB near Fairbanks, Alaska and at Hill AFB near Salt Lake
City, Utah. Four soil plots are being used to evaluate
passive, active, and buried heat tape soil-warming methods
Engineering Bulletin: In Situ Biodegradation Treatment
-------
during the Eielson study. The fourth plot was vented with
injected air but not artificially heated. Roughly 1 acre of soil
is contaminated from a depth of 2 feet to the water table at
6 to 7 feet At the Hill site, a series of soil gas cluster wells
capable of obtaining samples up to 90 feet deep is being
used with a single air injection well and two groundwater
wells to remediate JP-4 contamination found at depths
ranging from 35 feet to perched water at approximately 95
feet. Inert gas tracer studies, regular soil gas measurements
at several locations and depths, and periodic in situ respirom-
etry tests to measure in situ oxygen uptake rates are being
performed. Final soil hydrocarbon analyses will be con-
ducted at both sites in mid-1994 and compared with the
initial soil data. In situ respirometry data from the Hill site
(Table 1) indicate that petroleum hydrocarbons are being
removed at a significant rate. Intermediate respirometry
data from the test and control plots at the Eielson site
indicate that higher biodegradation rates are being ob-
tained at higher soil temperatures.[42][43].
Table 2,
Croundwater Quality After Seven Months of
Biosparging at the U.S. Coast Guard Air Station in
Traverse City, Michigan
Well Benzene
Depth (ft) (u,g/L)
Control
16
17.5
20.5
22
Sparge Plot
15
18
19.5
21
9.9
228
70
57
1.9
<1
<1
<1
Xylenes
(U.9/L)
19
992
38
7.7
5.3
5.0
<1
<1
Total Fuel
Carbon Oig/L)
2,880
4,490
956
783
559
<6
<6
<6
Table 1.
Rates of Biodegradation, Averaged Over Depth, at
Three Wells at Hill AFB
Well
CW-1
CW-2
CW-3
Depths Rate (mg/kg/day)
(ft) September 1991 September 19921
20-90
60-90
10-90
0.97
0.59
0.56
0.30
0.36
0.32
1 Since bloventing is being performed on a sandy soil, with
little to no naturally occurring organic matter, • biodegradation
rate approaching zero would indicate that biodegradation had
finished.
In November 1991, a pilot-scale bioventing system
originally used to treat gasoline-contaminated vadose soils
at the U.S. Coast Guard Air Station in Traverse City, Michi-
gan was converted into a groundwater biosparging pro-
cess. Eight 2-inch diameter sparge wells were installed to
a depth of 10 feet below the water table. A control plot
located in the vicinity of the contaminated plume, but not
biosparged, was established to help assess the system's
performance. After 12 months of biosparging, one-third of
the oily phase residue below the water table, as well as
almost all the BTEX initially present within the groundwater
plume, was removed. (See Table 2 for groundwater quality
data after 7 months of biosparging.) The globular nature of
the oily residue limited the surface area in contact with the
introduced air, thus restricting the biodegradation and
vaporization of the oily-phase contaminants [44][45].
Non-$uportund Sites
In situ biodegradation has been applied at many sites
in the private sector. Those interested in accessing informa-
tion generated in the private sector may want to refer to the
following EPA Publications:
U.S. Environmental Protection Agency.
Bioremediation Case Studies: Abstracts.
EPA/600/R-92/044, March 1992.
U.S. Environmental Protection Agency.
Bioremediation Case Studies: An Analysis of
Vendor Supplied Data. EPA/600/9-92/043,
March 1992.
Most of the data contained in these resources were
directly supplied by the vendor and have not been techni-
cally reviewed by EPA. Since independently-reviewed data
are not always available from privately sponsored remedial
efforts, in part due to proprietary issues [46, p. 1 -1 ], readers
should use these data cautiously. Often the quality of the
data used to determine system effectiveness has not been
substantiated by the scientific community. Thus, many
vendor claims of effectiveness, specifically regarding intro-
duced organisms and surface-active agents, are not sup-
ported within the scientific literature. Furthermore, many
bioremediation firms have only limited experience working
with the complex wastes normally associated with Super-
fund sites. Typically these firms deal only with gasoline and
petroleum product leaks and spills. Additionally, many of
the systems currently on the market involve the use of in situ
biodegradation in combination with other above-ground
treatment technologies such as carbon adsorption, air
stripping, and biological reactors. In situ biodegradation is
believed to enhance the total removal efficiency of the
system. However, in many cases, it is unclear how much of
the degradation occurred as a result of biological or non-
biological mechanisms (volatilization, chemical destruc-
tion, etc.). How much biodegradation actually takes place
in the soil or groundwater, in contrast to ex situ biodegra-
dation, is not always clear.
Engineering Bulletin: In Situ Biodegradation Treatment
-------
Technology Status
In situ biodegradation either has been considered or
selected as the remedial technology at 21 Superfund sites,
as well as 38 RCRA, UST, TSCA, and Federal sites[1][2][3].
Table 3 lists the location, primary contaminants, treatment
employed, and status of these sites. Information has also
been included on three in situ biotechnology demonstra-
tions presently being performed under the U.S. EPA Super-
fund Innovative Technology Evaluation (SITE) Program and
seven sites selected for performance evaluations under the
U.S. EPA Bioremediation Field Initiative. The data obtained
during the SITE demonstrations and Bioremediation Field
Initiative performance evaluations will be used to develop
reliable cost and performance information on biotreatment
technologies and applications.
The majority of the information found in Table 3 was
obtained from the August 1993 version of "Bioremediation
in the Field" [1 ]. These sites have been sorted numerically
by Region and then alphabetically by site name. Sites
employing "in situ land treatment" were not included in
this list since these applications typically involve a signifi-
cant amount of material handling. Additionally, some of
the information was modified based on phone calls made to
the various site project managers. This resulted in the
removal of the American Creosote Works site in Florida and
four pesticides sites (Ke-> the loliet Weed Control District
site in the loliet, Montana; the Lake County Weed Control
site in Ronan, Montana; the Miles Airport site in Miles City,
Montana; and the Richey Airport site in Richey, Montana)
[47], which are no longer considering in situ treatment.
Quarterly updates of this information can be obtained from
subsequent versions of "Bioremediation in the Field".
Most of the hardware components of in situ biodegra-
dation systems are available off-the-shelf and present no
significant availability problems. Selected cultures, nutri-
ents, and chemical/biological additives are also readily
obtainable.
Bioremediation, particularly in situ applications, which
avoid excavation and emissions control costs, are generally
considered cost effective. This can be attributed in part to
low operation and maintenance requirements. During set
up and operation, material handling requirements are mini-
mal, resulting in lowered worker exposures and reduced
health impacts. Although in situ technologies are generally
slow and somewhat difficult to control, a large volume of
soil may be treated at one time.
It is difficult to generalize about treatment costs since
site-specific characteristics can significantly impact costs.
Typically, the greater the number of variables requiring
control during biological treatment, the more problematic
the implementation and the higher the cost. For example,
it is less problematic to implement a technology in which
only one parameter (e.g., oxygen availability) requires
modification than to implement a remedy that requires
modification of multiple factors (e.g., pH, oxygen levels,
nutrients, microbes, buffering agents, etc.). Initial concen-
trations and volumes, pre- and post-treatment require-
ments, and air emissions and control systems will impact
final treatment costs. The types of amendments employed
(e.g., hydrogen peroxide) can also impact capital cost and
costs associated with equipment and manpower required
during their application.
In general, however, in situ bioremediation is consid-
ered to be a relatively low-cost technology, with costs as
low as 10 percent of excavation or pump and treat costs [7,
p. 6-16]. The cost of soil venting using a field-scale system
has been reported to be approximately $50 per ton as
compared to incineration, which was estimated to be more
than ten times this amount. A cost estimate of about $15
per cubic yard for bioventing sandy soil at a |P-4 jet fuel
contaminated site has been reported by Vogel [48]. Exclu-
sive of site characterization, the biological remediation of
jP-4 contaminated soils at the Kelly Air Force Base site was
estimated to be $160 to $230 per gallon of residual fuel
removed from the aquifer [9]. At the French Limited site in
Texas, the cost of bioremediation is projected to be almost
three times less expensive than incineration. Because of the
large amount of material requiring treatment at this site, it
has been projected that cleanup goals will be achieved in
less time by using bioremediation rather than incineration.
EPA Contact
Technology-specific questions regarding in situ bio-
degradation may be directed to:
Steve Safferman, EPA-RREL
Cincinnati, Ohio
(513)569-7350
John Matthews, EPA-RSKERL
Ada, Oklahoma
(405) 436-8600
Acknowledgments
This bulletin was prepared for the U.S. Environmental
Protection Agency, Office of Research and Development
(ORD), Risk Reduction Engineering Laboratory (RREL), Cin-
cinnati, Ohio, by Science Applications International Corpo-
ration (SAIQ under Contract No. 68-C8-0062 and Contract
No. 68-CO-0048. Mr. Eugene Harris served as the EPA
Technical Project Monitor. Mr. Jim Rawe served as SAIC's
Work Assignment Manager. This bulletin was authored by
Mr. Rawe and Ms. Evelyn Meagher-Hartzell of SAIC.
The following other Agency and contractor personnel
have contributed their time and comments by participating
in the expert review meetings or independently reviewing
the document:
Mr. Hugh Russell
Ms. Tish Zimmerman
Mr. Al Venosa
Dr. Robert Irvine
Dr. Ralph Portier
Mr. Clyde Dial
EPA-RSKERL
EPA-OERR
EPA-RREL
University of Notre Dame
Louisiana State University
SAIC
; I0 engineering Bulletin:!? Situ Biodegradation Treatment
-------
Table 3. Superfund, RCRA, UST. TSCATand Federal Sites*
She Location
(Regions)
Primary Contaminants
Status/Cost
Treatment
Chariestown Navy Yard
Boston, MA (T) <•„;'>'•/
Sediments: wood preserving (PAHs).
"- •
General Electric -
Woods Pond
Pfttsfietd. MA(1)
FAA Technfcal Center -
.
Atlanta County, NJ (2)
General Electric -
Hudson River, NY (2)
talp¥Conjtn>ctk>h
-
Picatinny Arsenal
NJ(2)
Ptottsburgh'AFB-rlV;
Plamburgh, NYXZ)'"
ARC
Gainesville, VA (3)
LA. Clarke & Son
Fredericksburg,VA(3)
*f'.*j-«
Charleston
Charleston, SC:{4)
EglinAFB
Ft (4)
Savannari[River StaT
Aiken,NC(4) „
,,S - , -!^tf S • ,
Stallworth Timber
Beatrice, AL (4)
Allied Chemical
Ironton, OH ->sv-r-^
B&FTruddng „ -,^,
Company '^U^
•^ •*•• -. \ \s >, . •• ; ;";i-"'|?
'; , \1,.,. \ ,<>,,! ,!.i ^, v\ *).<''Is? its
Anaerobic treatment confined treatment
facility, nutrient addition.
petroleum QetfueVNAPLs). ,
Volume 33K cubic*
t cubic yards.
Desigrt- pilot scale TS completed
8/927 , -,-'.„ , - , .
Expected cost capital, J286K;
OSM.X200K ,
Nutrient addition (soil, water).
Groundwater n>injecuoru! ::-•.-- •
Sediments: PCBs, cadmium,
chromium, lead.
Volume: ISO cubic feet
Soa/grpuifidwaten petroleum.
•'-^SfrM*"* •#*••><- v? -. v'A1- C< ^ "' "" ''
Soil (vadose)/soil vapors: solvents
(TCE).
Groundwater: petroleum: ;'
- - ~ VA .- , < ... . N *' ~
*."•*.'? >
Soil: solvent (chlorobenzene).
Volume: 2,000 cubic yards.
Predesign: lab scale TS
completed.
Incurred cost S2.6M.
Completed: full scale 1 0/89
Start date 01/89.
Incurred cost O&M, J25K.
Design: lab scale studies
completed.
Design: p¥ot'jcaie.! - ' *.'"-• '?
Start date (est): 3/94,, r>,
Aerobic treatment Less than 1% of site
underwent bioremediation.
Aerobic treatment hydrogen peroxide, >
nutrient addition (water). .100% of site
Aerobic treatment bioventing.
Co-metabolic degradation (methane,
propane, or natural gas) [27].
t.iv*-&y<^:ri * *"v.~.
nfing:-;-'v^,:^
Completed: full scale 6/91.
Start date: 10/89.
Aerobic treatment, bioventing.
Exogenous organisms. 5% of the site
underwent bioremediation.
water: petroleum, PAHs, TCE, solvents,
metals (te_ad iron, manganese). '
Four separate processes are :""•*•
planned. Field and lab TS results'
are expected 2/94 and 11/94. , ,
Sediments/soa: wood preserving.
Volume: 119K cubic yards.
Design: pilot scale TS started
7/927
Expected cost J23M.
sparging. Ex situ land treatment.,. .,;;:-
*.™, %'-;' i ' -o<-*'> ^,^'V^'.'. ^'^^^ ;<, '"
...<^ ^;- '' \-J '"* "v'"'',';>
^V^V^W,-?^ '.H ^J^V'^\v>i.^.^ V. „ ^'^SSf^Zv^
In situ treatment creosote recovery.
25% of site will undergo bioremediation.
fueO/Mtvents (1^
TCErVQ trans-l^-DCE; PCE;and
dkhkvomethaneX lead. ;".'•'
Volume: 25 -cubic yardsl -'', ',
„ „ •+&*}&*, *•**•.««% *fvf A, •"-, -A, i*'t
Soil (vadose): petroleum (jet fueQ.
mhMtef/sedirnehtK
chlorinated sofvents (TCE and PCE). ,
"
Expected completion 12/93.
-, -, .
Completed field scale study.
Operational: pilot scale research *
study;,;, /'• ; -- - ~
10% of the site under bioremediation.
-s'~. ~f% y, *z,,-~'"~~,'&§&. •••• ^Xj^>:-.'<.-.''
Soil (sand, silQ/qroundwater wood
preserving (PCP).
SedimenB (coal and coke fines): PAHj,
BTS^niCa':'' ' '"''••'' ' --f&f 'f '•' ' \
Volume: 500K cubic yards. •,', '„ ,;,V -
->;i;^ v^-Wx^f-- j*.4-^-.; x^«*v^ v -^ fr.vj*fft f* v> '
Soil (saturated)/groundwater BTEX.
SoH (vadose and sauiratedrg)/ground-
waten petroleum (lube oil), , ;
Volume: 700 cubic yards. Y :,
,;-.^ ' ^ •«-
$<**Xw -.^> ^'-- -• '•.\ii'' * ^ ^ .
Groundwater solvents (TCE, DCE,
DCA.VQ.
'redesign.
Design: pilot scale TS study , :
completed.
Expected cost J26M
Pilot scale TS completed.
Operational: full scale.
Start Date: 4/91.
Incurred cost $341K.
Predesign: lab scale TS underway.
In situ aerobic treatment nutrient
addition. Ex situ treatment activated
sludge, continuous flow. Exogenous and
indigenous organisms. 100% of site will
undergo bioremediation.
Aerobic treatment ''50%^ of site WHI'^?J,
undergo bioremediation. • „ .' • -.
Aerobk treatment air sparging [49].
n situ treatment Ex situ treatment
sequencing batch reactor, continuous ,,
flow. Aerobic conditions. 75% of site -,
under bioremediation. -
Aerobic and anaerobic treatment
Engineering Bulletin: In Situ Biodegradation Treatment
11
-------
Table 3. Superfund, RCRA, UST, TSCA, and Federal Sites (continued)
Site Location
(Regions)
Primary Contaminants
Status/Cost
Treatment
Un-named site*
Buchanan, Ml (5)
Croundwaten BTEX, PCE, TCE. DCL
Galesburg/Kopper
Catesburg, IL (5)
HeritcheHs ; ' -,
Traverse Gty, Ml (5) „';
Kenworth Truck Company
Chillkothe, OH (5)
K.L Sawyer AFB
Marquette,Ml(5) ,,.;. „ - >,
Soil: phenols, chlorophenol, PNAs,
PCP.MHs.
Sott/groundwaten petroleum.
Mayville Fire Department
Mayville, Ml (5)
Soil (vadose)/groundwater
solvents (BTEX, acetone, TPH).
Soil (vadose sand): petroleum.
Groundwater. petroleum.
Pilot Meld study started 3/93.
Expected completion 3/94.
Predesign.
Start date (est): 12/92.
Operational: full scale.
Start date: 9/85;
Design: lab scale TS completed.
Full scale system being installed.
Field TS report expected 10/93.
Michigan Air National Guard
Battle Creek, Ml (5) , - ,^
'
Newark AFB
Newark, OH (S)
Onalaika Municipal Landfill
Lacrosse County, Wl (5) -V ,„;
Parke-Oavis
Holland, Ml (5)
I, silt): petroleum, ,-
heavy metals.;, - >;,/;- ,~^~~.: - '*<
,"-. •," s*' J- v-. -x £ "" .. ,'.-,?-.;•'&/*, -• \ >iv.£i£ J" - s sj£
Soil (vadose: silt, day): petroleum
(gasoline).
' 'olume: 60 cubk yards.
Sofl (vadose and saturated sand):
solvents (TCE), petroleum (totai
hydra-carbons), wood preserving
(naphthalene). -,;,; ;, -v;4- -
Volume: 5,000 cubfc-yard$.,C;
'> 'v
Operational: full scale since 5/90.
Completion date (est): 1/94.
Design: pilot scale TS started 7
9/92. , - ; - ,-'
Start date (est): 9/93 , -
Expected cost: capital, J 3,000;
O&M, $1,268.; - ,,;, •',.'_ ' ;;
Design: pilot scale TS started
8/92. Expected completion
8/94.
Expected cost capital, S35K;
O&M, S2K.
Design: lab scale TS completed
3/52;,".: --V --,... --- '••
Expected cost capital, $400K*
OSM, J20K., ,
'
St Louis- Park, MN (5)-
Sheboygan River and Harbor
Sheboygan,IL(S)
West K&L Avenue e Lahdfiin
Kalamazoo, MI(S)
Wright-Patterson AFB
Dayton, Ohio (S)
taw Chemical Company,
••laquemine, LA (6)
Soil/groundwaten petroleum,
solvents, arsenic, chloride, zinc
So^ (\£dose loam): wood «iserviner
' '
Sediments (sand, silt, day): PCBs.
Volume: 2,500 cubic yards.
Groundwater sorvents (acetone;";,1" T"
TCE; trans-1,2-DCE; 1^-DCA;
1,1-DCA; BTEX; VC; methyl isobutyl
ketone; MEIC';. ~,,^- ,-;,>,„ A
^^ ^ „ , *vw ' -fe. *. , -.* s •• -.f.
Soil (vadose: sand, silt clay):
petroleum (jet fuel).
Volume: 7.5K cubk yards.
Groundwater: sorvents (1,1-DCA;
1,2-DCA;1;1.1-TCA;1,\-DCE,
chloroetnane).
Volume: 90K cubic yards.
French Limited
Crosby, TX (6)
Kelly AFB
San Antonio, TX (6)
Sediments (sand, silt)/sludge/soil
(sand, silt, clay)/groundwater
PCBs, arsenic, rofeum (BAP, VOCs),
arsenic
Soil (vadose clay): petroleum (jet
fuel), solvents (PCE, TCE. VC. DCE).
Predesign.
DesWntpilot'scaleTSstartedl *
11/92., Expected completion
11/95,;,' -. -,- •,
Incurred cost: S25K.
Expected cost J70K.
Lab and pilot scale TS are being
conducted.
Design: pilot and lab scale TS
ongoing. ,
Predesign: pilot scale studies
planned.
Expected completion 3/94.
Design: pilot scale started 3/93.
Expected cose capital, JIM;
O&M, SSOK.
Incurred cost capital, S250K;
O&M, S10IC
Operational: full scale since 1/92.
Expected cost J90M.
Operational: full scale since 2/93.
Completion data (est): 9/94.
Aerobic treatment.
Nutrient addition. 100% of site
under bioremediation.
Aerobic treatment, biospargihg.
In situ aerobic treatment, hydrogen
peroxide, nutrient addition
[nitrogen, phosphorus). Ex situ
treatment, GAC bioreactor. 100% of
site will undergo bioremediation.
Aerobic treatment, bioventfnij.
Aerobic treatment, air sparging.
100% of site will undergo
bioremediation.
Aerobic treatment biovent
100% of site will undergo-; ^. ;<,; 'a,
bioremediation.,, * „, ^^'»u
Aerobic treatment, bioventing. 40%
of site under bioremediation.
Aerobic treatment, Woventirig. 20%
of site will undergo bioremediation.;
^, ~*£', >„>•»«>£;;«~^,,>, "S1(J
Aerobic treatment, bioventing., "
19
Bulletin; Jn Situ Biodegradation Treatment
-------
Table 3. Supertund, RCRA, UST, TSCA, and Federal Sites (continued)
Site location
(Regions)
Primary Contaminants
Status/Cost
Fakfieti Coal & Gas
OffuttAFB
LaPlatte, NE (7)
fi&ditfj*",, •..
ParkOty,tCS<7)
SoR (saturated: sand, silt,.
dayVgroundwater: coal tar (8TEX,
. Aw ,«, s,
Son (vadose: sand, silt): petroleum
(TRPH), arsenic, barium, lead, zinc
Volume: 700 cubic yards.
Design: pilot scale IS started
12/9i. Ixpected completion
12/93.-- „ - ), A< -v,
ExpectedcosfcJ1.6M. <•" „"
" * .VW.VMM , ,>«„«*. * „•**.$&£&. •• viX
Design: pilot scale TS started
8/927
Aerobic treatment injection and -~**v<
extraction wells, hydrogen peroxide,
nitrate addition. , \ -.<;•,>;>„ •-*
;»•• ,-,- ,J»*V-.«x."i.kiC5-,--f,!;-4»l(ib,
Aerobic treatment bioventing. 10% of
site under bioremediation.
Groondwater petroleum (lube oil),
benzene* '< x - •• ** *' ^ A * - ^
Burlington Northern Tie
Plant
Somers, MT(8)
Ceraklln*
daho Pole Company
Bozeman, MT(8)
Soil/groundwater wood preserving
Volume: 82K cubk yards.
Sol (vadose: sand, silt, loam, day):
pesticides (aldrin; diddrin; endhn;,,
chkxdane;toxaphene;b-BHC; ,
4,4'.DDE; 4.4'J)DT; 4,4'-ODD);, , .
*»rt*^{2/«^^^r ':£-^
Sediments/soils/groundwater PCP,
PAHs, dioxins/furans.
Design: pilot scale TS completed.
Incurredcost: J275K.
Expected cojfc J650K. ,
Installed: full scale.
Start date (est): 7/92.
Expected cost SUM.
Predesign. ' ...'-.
Croundwater. In situ treatment i Possible
bioventing for soils. Anaerobic and -;- •
aerobic conditions I23][24j;t^v-£&l
•• s ^^^ -' S ^r-^.S^?v««\««.-X*.t4<«^Cs.t
In situ treatment Ex situ land treatment
Aerobic conditions. 80% of site will
undergo bioremediation.
In situ treatment fx situ1 treatment I ^ 7:
Aerobic and anaerobic conditions.
^
Jbby Croundwater Site1
Ubby, MT (8)
SoS: petroleum OP-*}etfueO.
Soil (vadose and saturated)/
jroundwaten wood preserving (PAHs,
jyrene, PCP, dioxin, naphthalene,
Jhenanthrene, benzene, arsenic).
Volume 4SK cubk yards.
-
Cpmp4etio^date;(es^9/S^
, t^M - - % ^? V* J- vV>» J.>»-'f-*jfWf«/*--^-X>»^-<<
^>»: ^ .->viA^i *>^-»i^ rsi^teiasj^ *
In sftu treatment oxygen enhancement
nutrient addition. Ex situ treatment,
lixed film, slurry reactor. Aerobk
conditions.
Aerobic treatment,5
site under bioremediation
Operational: three pilot scale
efforts ongoing.
ncurred cost MM.
TS results available (est): 8/93
and 4/94.
n situ treatment (groundwater), ex situ
land treatment (soil), nutrient addition
(soil, water). Also, treatment of
groundwater in bioreactor. Aerobic
conditions. 75% of site under
bioremediation.
BeateAFB
Marysvilte, CA(9)
RutriemaddrUwt:COfnbinedbi
Soil (vadose sitty clay): petroleum
[gasoline, dieseQ, solvents (TCE), lead.
volume: 163K cubic yards.
Seven processes are planned.
4 are in design (pilot scale),
I are in predesign (full scale), and
| b presently operating
completion date 7/95).
•xpected cost capital S500K;
0&M.136K.
Corporation Yard
MontabeMo/CA (9)
W*i*«^W*-vii Mvf^w ^A-^yv V J.V, *-»
ormer Service Station
Los Angeles, CA (9)
Marine Corps Air/
iround Combat Center
wenty-Nine Palms,
CA(9)7
'&<¥*•' f.V-fHlf&r •'Wift* v-f,\f ••f'-jH* «* }•
Naval AFStation'Falloh*,
alien, NV (9) s.
Soil/groundwater: petroleum.
Volume: 3,000 cubic yards.
w« \»^^*^»^^i« j«*»rwij -^*mjf yt^f^^^f •• <
cobbles): wood preserving (PCP; -
'AHs, dkwins/furanj), arsenic". ,
roturne'libx ttO&yif^-"t:l'>'\
•. ^,'^X**»'X%v"'^y^i^'itt»*'>s>^»^ft\'»»'"'' 'v*sjvwy'-ywi»!'
Aerobic treatment bioventing, nutrient
addition. 10%ofslteunder!,-- <, ~',g'
bioremediation.-,- ;, '-''=•'' --,•:'-.
Expected completion 11/94., ,-
Expected cost capital, "J4^M; ,
O&M, 57.7M.-rT/ ~:;:,,- r,:
DesignrfuTl scateT'"""
Aerobic treatment hydrogen peroxide,
nutrient addition (water), closed loop
system. 65% of site underwent
bioremediation.
Aerobk treatrne^'nub^a^dWoru'
30% of site win undergo bioremediation.,
20year remedial effort),,: ,,,,A,TV, V,-.,-?
• '.' ,H.-r -»-"-^r*? 3tc .v;:'!-
V/,,.; L , .,•/;.; ^^K.'ail&sa.'xi.ii/.:"
Aerobic treatment, bioventing.
saturated"'- I -~~ :
slrO/groundwater: petroleum (jet fuel,
p-xyfene. naphthalene, 1 -methyl ,:
naphthalene, n-butylbenzene),
. A „ *« ^ , ~*
Naval Weapons Station
Seal Beach, CA (9)
Oakland Chinatown ''"'*
Oakland, CA (9) 4;, ;
iroundwater. petroleum.
Soil (saturated sand): groundwater
Mtroleum. " -- •; '
Jesign: pilot scale TS started;
S conducted or in progress:
laboratory scale.
Volume:! OK cubk yards.
Completed: full scale 8/90.
"itart date: 3/89.
addition (soil), oil/water separation.
' J '' -. "" ,,,,."<•'
Engineering Bulletin: In Situ Biodegradation Treatment
13
-------
Table 3. Superfund, RCRA, UST, TSCA, and Federal Sites (continued)
Site Location
(Regions)
Primary Contaminants
Status/Cost
Treatment
San Diego Gas and
Electric
San Diego, CA(?)
wiiiams APR 2
Phoenix, AZ (9)
East 15th Street Service
Station-." ;,<;,',„
Anchorage, AK (10)
''m''">" """""""
Soii (sand): petroleum (gasoline).
Volume: 1,200 cubic yards.
Soil (vadose): petroleum (|P-4 jet fuel).
Sotl: petroleum (TPH diesel).
Volume; 1,500 cubic yards.
Completed: full scale 4/93.
Start date: 10/89.
Pilot field testing started 5/92.
Test completed 6/93.
Operational: full scale since 6/92.
Incurred cost: J75K.
Expected cost J200K. /
Fairbanks, Alaska (10)
Soil (sand/silt): petroleum (JP-4 jet
fueQ.
Operational: pilot full scale.
Start date: 9/91.
Completion date (est): 9/94.
SoB (vadose and saturated ~ ~*' ''*""'"
sitt)/groundwaten petroleum, solvents
(TO). '^,/'-;j- t \Xi"J,X--l -S ' -'
••" '
3 separate processes are planned.
The first process is in pre-design;
a pilot scale TS should start 1/95.
The remaining two started pilot ,
scale TSs in 4/93. ' 4*
Aerobic treatment. 100% of site
underwent bioremediation [5];
In situ treatment bacterial
supplementation (non-indigenous micro
aerofilic bacteria).
Aerobic treatment, bioventing, 20% of-'.
site under bioremediation. .. ,>•',," *:
Aerobic treatment, bioventing, soil
warming [42]
.,„,,..: , < T" LV ' -- ^^"•Sffpw'^xw¥»"-
Aerobic treatment, bioventfnoj nutrient
addition. - ,, ,,„,.. --' '
TS-Treatability Study
1 Bioremediation Field Initiative
2 Superfund Innovative Technology Evaluation (SITE) Demonstration
REFERENCES
1. U.S. Environmental Protection Agency. Bioremediation
in the Field. EPA/540/N-93/002. August 1993.
2. U.S. Environmental Protection Agency. Superfund Inno-
vative Technology Evaluation Program: Technology Pro-
files, Sixth Edition. EPA/540/R-93/526, November
1993.
3. U.S. Environmental Protection Agency. Bioremediation
Field Initiative. EPA/540/F-93/S10, September 1993.
4. U.S. Environmental Protection Agency. Handbook on
InSitu Treatment of Hazardous Waste-Contaminated
Soils. EPA/540/2-90/002, Cincinnati, Ohio, January
1990.
5. Cersberg, R.M., W.j. Dawsey, and H. Ridgeway. Draft
Final Report: In-Situ Microbial Degradation of Gasoline.
EPRI Research Report Number RP 2795-2.
6. Norn's, R.D., K. Dowd, and C. Maudlin. The Use of Mul-
tiple Oxygen Sources and Nutrient Delivery Systems to
Effect In Situ Bioremediation of Saturated and Unsatur-
ated Soils. Presented in: Symposium on Bioremediation
of Hazardous Wastes: Research, Development, and
Field Evaluations. EPA/600/R-93/054, May 1993.
7. Hopkins, C.D., L Semprini, and P. McCarty. Field
Evaluation of Phenol for Cometabolism of Chlorinated
Solvents. In: Symposium on Bioremediation of Hazard-
ous Wastes: Research, Development, and Held Evalua-
tions. EPA/600/R-93/054, May 1993.
8. Hopkins C.D., L Semprini, and P.L McCarty. Evalua-
tion of Enhanced In Situ Aerobic Biodegradation of CIS-
and Trans-1-Trichloroethylene and OS- and Trans-1,2-
Dichloroethylene by Phenol-Utilizing Bacteria. In:
Bioremediation of Hazardous Wastes. EPA/600/r-92/
126, August 1992.
9. Abrarnowkz, et al. 1991 In Situ Hudson River Research
Study: A Field Study on Biodegradation of PCBs in
Hudson River Sediments - Final Report February 1992.
10. U.S. Environmental Protection Agency. Superfund LDR
Guide #6A: Obtaining a Soil and Debris Treatability Vari-
ance for Remedial Actions. OSWER Directive 9347.3-
06FS, September 1990.
11. U.S. Environmental Protection Agency. Superfund LDR
Guide #6B: Obtaining a Soil and Debris Treatability Vari-
ance for Removal Actions. OSWER Directive 9347.3-
06BFS, September 1990.
12. Sims,)., R. Sims, and J. Matthews. Bioremediation of
Contaminated Surface Soils. EPA/600/9-89/073, August
1989.
13. Sims, ]., R. Sims, R. Dupont, |. Matthews, and H. Russell.
Engineering Issue - In Situ Bioremediation of Contami-
nated Unsaturated Subsurface Soils. EPA/540/S-93/501,
May 1993.
14. Piotrowski, M.R. Bioremediation: Testing the Waters.
Civil Engineering, August 1989. pp. 51-S3.
In Situ Biodegradation Treatment
-------
15. U.S. Environmental Protection Agency! International
Evaluation of In-Situ Biorestoration of Contaminated Soil
and Croundwater. EPA/540/2-90/012, September
1990.
16. U.S. Environmental Protection Agency. Handbook: Re-
medial Actions at Waste Disposal Sites (Re-
vised). EPA/625/6-85/006, Cincinnati, Ohio, October
1985.
17. U.S. Environmental Protection Agency. Review of In-
Place Treatment Techniques for Contaminated Surface
Soils. Volume 2: Background Information for In Situ
Treatment EPA/540/2-84/003b, Cincinnati, Ohio, No-
vember 1984.
18. Hazen, T.C. Test Plan for In Situ Bioremediation Dem-
onstration of the Savannah River Integrated Demonstra-
tion Project DOE/OTD TTP No.: SR 0566-01 (U). U.S.
Department of Energy, WSRC-RD-91-23, Revision 3,
April 23,1992.
19. U.S. Department of Energy. Cleanup of VOCs in Non-
Arid Soils - The Savannah River Integrated Demonstra-
tion. WSRC-MS-91-290, Rev. 1, pg. 6.
20. U.S. Environmental Protection Agency. Technology
Screening Guide for Treatment of CERCLA Soils and
Sludges. EPA/540/2-88/004, September 1988.
21. U.S. Environmental Protection Agency. SITE Demon-
stration Bulletin - Augmented In Situ Subsurface
Bioremediation Process, BIO-REM, Inc, EPA/540/MR-
93/527, November 1993.
22. McCarty P. and |. Wilson. Natural Anaerobic Treatment
of a TCE Plume, St Joseph, Michigan, NPL Site. In:
Bioremediation of Hazardous Wastes. EPA/600/R-92/
126, August 1992.
23. Hutchins, S.R., and J.T. Wilson. Nitrate-Based
Bioremediation of Petroleum-Contaminated Aquifer at
Park City, Kansas: Site Characterization and Treatability
Study. In: Hydrocarbon Bioremediation. R.E. Hinchee,
B.C Alleman, R.E. Hoeppel, and R.N. Miller, ed. CRC
Press, Boca Raton, Florida, 1994.
24. Kennedy, L.G., and S.R. Hutchins. Applied Geologic,
Microbiological, and Engineering Constraints of In-Situ
BTEX Bioremediation. Remediation. Winter 1992/93.
25. New York State Department of Environmental Conserva-
tion. Final Report, Knispel Construction Company,
Horseheads, New York, October 1990.
26. Mariey, M.C., et al. The Application of the In Situ Air
Sparging as an Innovative Soils and Groundwater Reme-
diation Technology. Groundwater Monitoring Review,
pp. 137-144, Spring 1992.
27. Federal Remediation Technologies Roundtable. Synop-
ses of Federal Demonstrations of Innovative Site Reme-
diation Technologies. EPA/542/B-92/003, August 1992.
28. U.S. Environmental Protection Agency. Vendor Informa-
tion System for Innovative Treatment Technologies
(VISITT). EPA/540/2-91/001, June 1991.
29. U.S. Environmental Protection Agency. A Gtizen's
Guide to Bioventing. EPA/542/F-92/008, March 1992.
30. U.S. Environmental Protection Agency. Bioremediation
in the Field. EPA/540/2-91 /018, August 1991.
31. U.S. Environmental Protection Agency. Bioremediation
in the Field. EPA/540/N-91/001, March 1992
32. U.S. Environmental Protection Agency. The Superfund
Innovative Technology Evaluation Program: Technology
Profiles, Fifth Edition. EPA/540/R-92/077, December
1992.
33. Hinchee, R.E., D.C. Downey, R.R. DuPont, P.K.
Aggarwal, and R.N. Miller. Enhancing Biodegradation
of Petroleum Hydrocarbons through Soil Venting, jour-
nal of Hazardous Materials, Vol. 27,1991.
34. Nelson, C.H. A Natural Cleanup. Civil Engineering,
March 1993.
35. Wilson, J.T., and D.H. Kampbell. Retrospective Perfor-
mance Evaluation on In Situ Bioremediation: Site Char-
acterization. In: Symposium on Bioremediation of
Hazardous Wastes: Research, Development, and Field
Evaluations. EPA/600/R-93/054, May 1993.
36. Day, S., K. Malchowsky, T. Schultz. P. Sayre, and G.
Saylor. Draft Issue Paper Potential Risk, Environmental
and Ecological Effects Resulting From the Use of GEMS
for Bioremediation. U.S. Environmental Protection
Agency, Office of Pollution Prevention, April 1993.
37. Hopkins, G.D., L Semprini, and P.L McCarty. Held
Study of In Situ Trichloroethylene Degradation in
Groundwater by Phenol-Oxidizing Microorganisms. In:
Abstract Proceedings Nineteenth Annual RREL Hazard-
ous Waste Research Symposium. EPA/600/R-93/040,
April 1993.
38. Beeman, R., S. Shoemaker, j. Howell, E. Salazar, and j.
Buttram. A Reid Evaluation of In Situ Microbial Reduc-
tive Dehalogenation by the Biotransformation of Chlori-
nated Ethylenes. In: Bioremediation of Chlorinated
Polycydic Aromatic Hydrocarbon Compounds. R.E.
Hinchee, A. Leeson, L Sempini, and S.K. Ong, ed. CRC
Press, Boca Raton, Florida, 1994.
39. Norris, R.D., K. Dowd, C. Maudlin, and W.W. Irwin. The
Use of Multiple Oxygen Sources and Nutrient Delivery
Systems to Effect In Situ Bioremediation of Saturated
and Unsaturated Soils In: Hydrocarbon Bioremediation.
R.E. Hinchee, B.C. Alleman, R.E. Hoeppel, and R.N.
Miller, ed. CRC Press, Boca Raton, Florida, 1994.
40. U.S. Air Force Correspondence. Subject: Air Force's
Bioventing Initiative. July 1993.
41. U.S. Environmental Protection Agency. Bioremediation
in the Field. EPA/540/N-92/004, October 1992.
42. Sayles, G.D., R.E. Hinchee, C.M. Vogel, R.C. Brenner,
and R. N. Miller. An Evaluation of Concurrent
Bioventing of jet Fuel and Several Soil Warming Meth-
ods: A Field Study at Eielson Air Force Base, Alaska. In:
Symposium on Bioremediation of Hazardous Wastes:
Research, Development, and Field Evaluations. EPA/
600/R-93/0-54, May 1993.
43. Sayles, G.D., R.E. Hinchee, FLC. Brenner, and R. Elliot
Engineering Bulletin: In Situ Biodegradation Treatment
IS
•&U.S. GOVEKNMCNT PUNTING OFFICE: MM • SM467/MU4
-------
Documenting Bioventing of Jet Fuel to Great Depths: A
Field Study at Hill Air Force Base, Utah. In: Symposium
on Bioremediation of Hazardous Wastes: Research, De-
velopment, and Field Evaluations. EPA/600/R-93/0-54,
May 1993.
44. Kampbell, D.H., J.T. Wilson, and C.|. Griffin. Perfor-
mance of Bioventing at Traverse Gty, Michigan. In:
Bioremediation of Hazardous Wastes. EPA/600/r-92/
126, August 1992.
45. Kampbell, D.H., G.J Griffin, and FA Blaha. Comparison
of Bioventing and Air Sparging for In Situ
Bioremediation of Fuels. In: Symposium on
Bioremediation of Hazardous Wastes: Research,
Development, and Field Evaluations. EPA/600/R-
93/054, May 1993.
46. U.S. Environmental Protection Agency. Summary Re-
port on the EPA-lndustry Meeting on Environmental Ap-
plications of Biotechnology. February 1990.
47. Remediation Technologies, Inc. Results of Biotreatability
Testing of Pesticide- and Herbicide-Contaminated Soils
from Richey Airport in Richey, Montana. For Montana
Department of Health and Environmental Sciences. Oc-
tober 1993.
48. Vogel, C. Enhanced In Situ Biodegradation of Petroleum
Hydrocarbons Through Soil Venting. Tech data
RDV91-7, Air Force E&S Center, Tyndall AFB, Florida.
1991.
49. Barker, G.W., Y.|. Beausoleil, J.S. Huber, and S.N.
Neumann. Application of In Situ Air Sparging at a Hy-
drocarbon Contaminated Groundwater Site. In:
Speaker Abstracts: In Situ and On-Site Bioredamation -
The Second International Symposium. San Diego, Cali-
fornia, April 5-8,1993.
50. Minnesota Pollution Control Agency. Rally Tar
Bioventing Demonstration - Superfund Fact Sheet
January 1993.
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/540/S-94/502
-------
Section 12
-------
SOIL WASHING AND
SOLVENT EXTRACTION
STUDENT PERFORMANCE OBJECTIVES
At the conclusion of this unit, students will be able to:
1. Describe the in situ soil flushing process
2. Name three solvent types and the applicable contaminant
each removes
3. Describe the process residuals generated during soil flushing
and their disposition
4. Describe four limitations to the use of soil flushing
5. Describe the soil washing process
6. Define which size soil particles are suitable for soil washing
7. Describe the process residual generated during soil washing,
and their disposition
8. Describe four limitations to the use of soil washing
9. Describe the solvent extraction process
NOTE: Unless otherwise stated, the conditions for
performance are using all references and materials
provided in the course, and the standards of
performance are without error.
7/95
-------
STUDENT PERFORMANCE OBJECTIVES (cont.)
10. Describe the four process steps in the solvent extraction
operation
11. Describe the residuals generated during solvent extraction
and their disposition
12. Describe four limitations to the solvent extraction process.
NOTE: Unless otherwise stated, the conditions for
performance are using all references and materials
provided in the course, and the standards of
performance are without error.
Soil Washing and Solvent Extraction 7/95
-------
SOIL WASHING AND
SOLVENT EXTRACTION
8-1
SOIL WASHING TREATMENTS
SOIL TREATMENTS
• In-situ soil flushing
• Soil washing — ft hri**
• Solvent extraction
8-2
S-3
NOTES
7/95
Soil Washing and Solvent Extraction
-------
NOTES
v
IN-SITU SOIL FLUSHING
In-situ soil flushing is the extraction of
contaminants from the soil with water or
other suitable aqueous solutions
US. EPA 1091*
8-4
s-s
S-8
5o/7 Washing and Solvent Extraction
7/95
-------
NOTES
I
3-7
S-8
7/95
Soil Washing and Solvent Extraction
-------
NOTES
SOLVENT SELECTION
Water
- Soluble (hydrophilic) organics
- Octanol/water partition coefficient <10
Water with surfactant
- Low solubility (hydrophobic) organics
S-11
SOLVENT SELECTION (cont.)
Acids, chelating agents, or reducing
agents
- Metals
- Inorganic metal salts
S-12
Soil Washing and Solvent Extraction
7/95
-------
NOTES
DEMONSTRATED
EFFECTIVENESS
Volatile halogenated organics
(perchloroethylene, chloromethane)
Semivolatile nonhalogenated organics
(phenols, nitrobenzene)
Nonvolatile metals (arsenic, lead)
U.S. EPA 1891*
8-13
SOIL PARAMETERS
Permeability - affects treatment time and
efficiency of contaminant removal
- >1 x 10'3 cm/sec = effective soil
flushing
- <1 x 1Q-5 cm/sec = limited soil flushing
8-14
SOIL PARAMETERS (cont.)
Moisture content - affects flushing fluid
transfer requirements
Groundwater hydrology - critical in
controlling the recovery of injected fluids
and contaminants
S-15
7/95
Soil Washing and Solvent Extraction
-------
NOTES
PROCESS RESIDUALS
Groundwater treatment
Flushing additives:
- Reuse
- Degradability
3-18
SITE REQUIREMENTS
Underground Injection Control (DIG) permit
National Pollution Discharge Elimination
System (NPDES)
Slurry walls or sheet piling for containment
Berms, dikes, or caps for surface water
control
8-17
SOIL FLUSHING LIMITATIONS
•1-2 years as concentrations decrease
• Hydraulic control required
• High silt and clay content not applicable
• Surfactants or organic solvents removed
• Bacteria and/or iron fouling
• Additives may interfere with wastewater
treatment
S-18
S&il Washing and Solvent Extraction
7/95
-------
SOIL WASHING
Soil washing is a water-based process for
mechanically separating and scrubbing soils
ex situ to remove undesirable contaminants
S-19
SOIL WASHING TREATMENT
Onsite, ex-situ, water-based process r~
Contamination reduction by particle size
separation
Mechanical washing and separation
techniques
Combines mining and chemical plant
technologies
S-20
APPLICABILITY
Stand alone or treatment train
Effective for coarse sand and gravel
Demonstrated contaminant removal
- Halogenated volatile organics
(perchloroethylene, trichloroethylene)
- Nonhalogenated volatile organics
(phenols, nitrobenzene)
- Volatile and nonvolatile metals
(mercury-volatile, lead-nonvolatile)
S-21
NOTES
'-if
7/95
Soil Washing and Solvent Extraction
-------
NOTES
WASTE SOIL CHARACTERIZATION
PARAMETERS
Particle Size
Distribution
>2 mm
0.25-2 mm
0.063-0.25 mm
<0.063 mm
Comments
Oversize pretreatment requirements
Effective soil washing
Limited soil washing
Day and silt fraction, difficult soil washing
8-22
Stones
S@IL WASHER
Soil fines
Clean sand
8-23
Spent fluid
Raw feed FINES WASHER
-s:
Clean
soil
8-24
Soil Washing and Solvent Extraction
7/95
-------
NOTES
Spent fluid
Raw feed SOIL FLOW
Spent
fluid
Rawfeed LIQUID FLOW
Clean soil
S-2S
SOIL WASHING SYSTEM
/CONTAMINATED SOIL ^ I POLYMER |
Centrifuges r
_ _. ^ ^ | Froth flotation
cells
• TO DISPOSAL |
8-27
7/95
Soil Washing and Solvent Extraction
-------
NOTES
SOIL WASHING RESIDUALS
• Wastewater - treatment and recycle
• Vapors - collect and treat
• Oversize soils - return to site
• Fines - further treatment
8-28
SOIL WASHING LIMITATIONS
• High percentage of silt and clay particles
• Hydrophobic contaminants
• Complex contaminant mixtures
• Additives may interfere with wastewater
treatment
S-29
SOLVENT EXTRACTION
Solvent extraction uses an organic solvent
in combination with standard soil washing
techniques to remove and concentrate
organic contaminants for further treatment
S-30
Soil Washing and Solvent Extraction
10
7/95
-------
NOTES
SOLVENT EXTRACTION (cont.)
• Contaminants separated for volume
reduction
• One in a series of unit operations
• Organic chemical solvent
• Site-specific solvent selected
S-31
APPLICABILITY
Sediments, sludges, and soils
Semivolatile halogenated organics
(dichlorobenzene)
Volatile nonhalogenated organics (benzene)
Semivolatile nonhalogenated organics
(phenols)
Polychlorinated biphenyls (PCBs)
Pesticides
3-32
PRETREATMENT
• Physical
- Size reduction and classification
- Dewater or water addition
• Chemical
- pH adjustment
S-33
7/95
11
Soil Washing and Solvent Extraction
-------
NOTES
SOLVENT SELECTION
Standard solvents
Liquefied gas (LG)
Critical solution temperature (CST)
solvents
S-34
PROCESS STEPS
Extraction
Separation
Desorption
Solvent recovery
S-35
STANDARD SOLVENT
EXTRACTION PROCESS
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US. EPA 1994*
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5oi7 Washing and Solvent Extraction
12
7/95
-------
NOTES
PROCESS RESIDUALS
• Treated solids
- Dewatering
- Residual solvent removal
- Metal contaminant removal
• Organic solvents
- Organically bound metals
• Solvent/water mixture
• Air emissions
S-37
PROCESS LIMITATIONS
Organically bound metals
Detergent and emulsifiers
Extraction solvents on treated solids
High molecular weight organics
Hydrophilic substances
S-38
7/95
13
Soil Washing and Solvent Extraction
-------
REFERENCES
U.S. EPA. 1990. Engineering Bulletin: Soil Washing Treatment. EPA/540/2-90/017. U.S.
Environmental Protection Agency, Office of Emergency and Remedial Response, Washington, DC,
and Office of Research and Development, Cincinnati, OH.
U.S. EPA. 1991a. Engineering Bulletin: In Situ Soil Flushing. EPA/540/2-91/021. U.S.
Environmental Protection Agency, Office of Emergency and Remedial Response, Washington, DC,
and Office of Research and Development, Cincinnati, OH.
U.S. EPA. 1991b. Guide for Conducting Treatability Studies Under CERCLA: Soil Washing.
Quick Reference Fact Sheet. EPA/540/2-91/020B. U.S. Environmental Protection Agency, Office
of Solid Waste and Emergency Response, Office of Emergency and Remedial Response, Washington,
DC.
U.S. EPA. 1992a. Guide for Conducting Treatability Studies Under CERCLA Solvent Extraction.
Interim Guidance. EPA/540/R-92/016a. U.S. Environmental Protection Agency, Office of
Emergency and Remedial Response, Washington, DC.
U.S. EPA. 1992b. Guide for Conducting Treatability Studies Under CERCLA: Solvent Extraction.
Quick Reference Fact Sheet. EPA/540/R-92/016b. U.S. Environmental Protection Agency, Office
of Solid Waste and Emergency Response, Office of Emergency and Remedial Response, Washington,
DC.
U.S. EPA. 1993. Applications Analysis Report: Resources Conservation Company B.E.S.T.®
Solvent Extraction Technology. EPA/540/AR-92/079. U.S. Environmental Protection Agency,
Office of Research and Development, Washington, DC.
U.S. EPA. 1994a. Engineering Bulletin: Solvent Extraction. EPA/540/S-94/503. U.S.
Environmental Protection Agency, Office of Emergency and Remedial Response, Washington, DC,
and Office of Research and Development, Cincinnati, OH.
U.S. EPA. 1994b. Superfund Innovative Technology Evaluation: Technology Demonstration
Summary, EPA RREL's Mobile Volume Reduction Unit. EPA/540/SR-93/508. U.S. Environmental
Protection Agency, Risk Reduction Engineering Laboratory, Cincinnati, OH.
Soil Washing and Solvent Extraction 14 7/95
-------
v>EPA
United States
Environmental Protection
Agency
Office of Emergency and
Remedial Response
Washington. DC 20460
Office of
Research and Development
Cincinnati, OH 45268
Superfund
EPA/540/2-91/021
October 1991
Engineering Bulletin
In Situ Soil Flushing
Purpose
Section 121(b) of the Comprehensive Environmental Re-
sponse, Compensation, and Liability Act (CERCLA) mandates
the Environmental Protection Agency (EPA) to select remedies
that "utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the maxi-
mum extent practicable" and to prefer remedial actions in
which treatment "permanently and significantly reduces the
volume, toxicity, or mobility of hazardous substances, pollut-
ants, and contaminants as a principal element" The Engineer-
ing Bulletins are a series of documents that summarize the latest
information available on selected treatment and site remediation
technologies and related issues. They provide summaries of
and references for the latest information to help remedial project
managers, on-scene coordinators, contractors, and other site
cleanup managers understand the type of data and site char-
acteristics needed to evaluate a technology for potential appli-
cability to their Superfund or other hazardous waste site. Those
documents that describe individual treatment technologies fo-
cus on remedial investigation scoping needs. Addenda will be
issued periodically to update the original bulletins.
Abstract
In situ soil flushing is the extraction of contaminants from
the soil with water or other suitable aqueous solutions. Soil
flushing is accomplished by passing the extraction fluid through
in-place soils using an injection or infiltration process. Extraction
fluids must be recovered and, when possible, are recycled. The
method is potentially applicable to all types of soil contami-
nants. Soil flushing enables removal of contaminants from the
soil and is most effective in permeable soils. An effective
collection system is required to prevent migration of contami-
nants and potentially toxic extraction fluids to uncontaminated
areas of the aquifer. Soil flushing, in conjunction with in situ
bioremediation, may be a cost-effective means of soil remedia-
tion at certain sites [1, p. vi][2, p. 11].* Typically, soil flushing
is used in conjunction with other treatments that destroy con-
taminants or remove them from the extraction fluid and
groundwater.
Soil flushing is a developing technology that has had lim-
ited use in the United States. Typically, laboratory and field
treatability studies must be performed under site-specific condi-
tions before soil flushing is selected as the remedy of choice. To
* [reference number, page number]
date, the technology has been selected as part of the source
control remedy at 12 Superfund sites. This technology is
currently operational at only one Superfund site; a second is
scheduled to begin operation in 1991 [3][4]. EPA completed
construction of a mobile soil-flushing system, the In Situ
Contaminant/Treatment Unit, in 1988. This mobile soil-flush-
ing system is designed for use at spills and uncontrolled hazard-
ous waste sites [5].
This bulletin provides information on the technology appli-
cability, the technology limitations, a description of the tech-
nology, the types of residuals resulting from the use of the
technology, site requirements, the latest performance data, the
status of the technology, and sources of further information.
Technology Applicability
In situ soil flushing is generally used in conjunction with
other treatment technologies such as activated carbon, biodeg-
radation, or chemical precipitation to treat contaminated
groundwater resulting from soil flushing. In some cases, the
process can reduce contaminant concentrations in the soil to
acceptable levels, and thus serve as the only soil treatment
technology. In other cases, in situ biodegradation or other in
situ technologies can be used in conjunction with soil flushing
to achieve acceptable contaminant removal efficiencies. In
general, soil flushing is effective on coarse sand and gravel
contaminated with a wide range of organic, inorganic, and
reactive contaminants. Soils containing a large amount of clay
and silt may not respond well to soil flushing, especially if it is
applied as a stand-alone technology.
A number of chemical contaminants can be removed from
soils using soil flushing. Removal efficiencies depend on the
type of contaminant as well as the type of soil. Soluble (hydro-
philic) organic contaminants often are easily removed from soil
by flushing with water alone. Typically, organics with octanol/
water partition coefficients (K^) of less than 10 (log K^l) are
highly soluble. Examples of such compounds include lower
molecular weight alcohols, phenols, and carboxylic acids [6].
Low solubility (hydrophobic) organics may be removed by
selection of a compatible surfactant [7]. Examples of such
compounds include chlorinated pesticides, polychlorinated bi-
phenyls (PCBs), semivolatiles (chlorinated benzenes and poly-
nuclear aromatic hydrocarbons), petroleum products (gasoline,
-------
jet fuel, kerosene, oils and greases), chlorinated solvents
(trichloroethene), and aromatic solvents (benzene, toluene, xy-
lenes and ethylbenzene) [8]. However, removal of some of
these chemical classes has not yet been demonstrated.
Metals may require acids, chelating agents, or reducing
agents for successful soil flushing. In some cases, all three types
of chemicals may be used in sequence to improve the removal
efficiency of metals [9]. Many inorganic metal salts, such as
carbonates of nickel, zinc, and copper, can be flushed from the
soil with dilute acid solutions [6]. Some inorganic salts such as
sulfates and chlorides can be flushed with water alone.
In situ soil flushing has been considered for treating soils
contaminated with hazardous wastes, including pentachloro-
phenol and creosote from wood-preserving operations, organic
solvents, cyanides and heavy metals from electroplating resi-
dues, heavy metals from some paint sludges, organic chemical
production residues, pesticides and pesticide production resi-
dues, and petroleum/oil residues [10, p. 13][11, p. 8][7][12].
The effectiveness of soil flushing for general contaminant
groups [10, p. 13] is shown in Table 1. Examples of constitu-
ents within contaminant groups are provided in Reference 10,
'Technology Screening Guide For Treatment of CERCLA Soils
and Sludges." Table 1 is based on currently available informa-
tion or professional judgment where definitive information is
Table 1
Effectiveness of Soil Flushing on General
Contaminant Groups
Contaminant Croups
1
1.0 x 1O'3 cm/sec), but may have limited
application to less permeable soils (1.0 x 1O'5 cm/sec < K < 1.0 x
10"3 cm/sec). Since there can be significant lateral and vertical .
variability in soil permeability, it is important that field measure-
ments be made using the appropriate methods.
Prior to field implementation of soil flushing, a thorough
groundwater hydrologic study should be earned out. This
should include information on seasonal fluctuations in water
level, direction of groundwater flow, porosity, vertical and hori-
zontal hydraulic conductivities, transmissivity and infiltration
(data on rainfall, evaporation, and percolation).
Moisture content can affect the amount of flushing fluids
required. Dry soils will require more flushing fluid initially to
mobilize contaminants. Moisture content is also used to calcu-
late pore volume to determine the rate of treatment [15].
The concentration and distribution of organic contami-
Engineering Bulletin: In Sttu Soil Flushing
-------
Table 2
Characterization Parameters
Parameter
Purpose and Comment
Soil permeability
21.0 x 10'3 cm/sec
<1 .Ox TO'5 cm/sec
Soil structure
Soil porosity
Moisture content
Groundwater hydrology
Organic*
Concentration
Solubility
Partition
coefficient
Metals
Concentration
Solubility products
Reduction potential
Complex stability
constants
Total Organic Carbon
(TOQ
Clay content
Cation Exchange
Capacity (CEC)
pH, buffering
capacity
Affects treatment time and
efficiency of contaminant removal
Effective soil flushing
Limited soil flushing
Influences flow patterns
(channeling, blockage)
Determines moisture capacity of soil
at saturation (pore volume)
Affects flushing fluid transfer
requirements
Critical in controlling the recovery
of injected fluids and contaminants
Determine contaminants and
assess flushing fluids required,
flushing fluid compatibility,
changes in flushing fluid with
changes in contaminants.
Concentration and species of cons-
tituents will determine flushing fluid
compatibility, mobility of metals,
post treatment
Adsorption of contaminants on
soil increases with increasing TOC.
Important in marine wetland sites,
which typically have high TOC.
Adsorption of contaminants on soil
increases with increasing clay
content
May affect treatment of metallic
compounds.
May affect treatment additives
required, compatibility with
equipment materials of construc-
tion, wash fluid compatibility.
nants and metals are key chemical parameters. These param-
eters determine the type and quantity of flushing fluid required
as well as any post-treatment requirements. The solubility and
partition coefficients of organics in water or other solutions are
also important in the selection of the proper flushing fluids.
The species of metal compounds present will affect the solubil-
ity and teachability of heavy metals.
High humic content and high cation exchange capacity
tend to reduce the removal efficiency of soil flushing. Some
organic contaminants may adsorb to humic materials or clays
in soils and, therefore, are difficult to remove during soil flush-
ing. Similarly, the binding of certain metals with clays due to
cationic exchange makes them difficult to remove with soil
flushing. The buffering capacity of the soil will affect the
amount required of some additives, especially acids. Precipita-
tion reactions (resulting in clogging of soil pores) can occur due
to pH changes in the flushing fluid caused by the neutralizing
effect of soils with high buffering capacity. Soil pH can affect
the speciation of metal compounds resulting in changes in the
solubility of metal compounds in the flushing fluid.
Limitations
Generally, remediation times with this technology will be
lengthy (one to many years) due to the slowness of diffusion
processes in the liquid phase. This technology requires hydrau-
lic control to avoid movement of contaminants offsite. The
hydrogeology of some sites may make this difficult or impos-
sible to achieve.
Contaminants in soils containing a high percentage of silt-
and day-sized particles typically are strongly adsorbed and
difficult to remove. Also, soils with silt and clay tend to be less
permeable. In such cases, soil flushing generally should not be
considered as a stand-alone technology.
Hydrophobic contaminants generally require surfactants
or organic solvents for their removal from soil. Complex mix-
tures of contaminants in the soil (such as a mixture of metals,
nonvolatile organics, and semivolatile organics) make it difficult
to formulate a single suitable flushing fluid that will consistently
and reliably remove all the different types of contaminants from
the soil. Frequent changes in contaminant concentration and
composition in the vertical and horizontal soil profiles will com-
plicate the formulation of the flushing fluid. Sequential steps
with frequent changes in the flushing formula may be required
at such complex sites [10, p. 77].
Bacterial fouling of infiltration and recovery systems and
treatment units may be a problem particularly if high iron
concentrations are present in the groundwater or if biodegrad-
able reagents are being used.
While flushing additives such as surfactants and chelants
may enhance some contaminant removal efficiencies in the soil
flushing process, they also tend to interfere with the down-
stream wastewater treatment processes. The presence of these
additives in the washed soil and in the wastewater treatment
sludge may cause some difficulty in their disposal. Costs associ-
ated with additives, and the management of these additives as
part of the residuals/wastewater streams, must be carefully
weighed against the incremental improvements in soil-flushing
performance that they may provide.
Engineering Bulletin: In Situ Soil Flushing
-------
Technology Description
Figure 1 is a general schematic of the soil flushing process [18, p.
7]. The flushing fluid is applied (1) to the contaminated soil by
subsurface injection wells, shallow infiltration galleries, surface flood-
ing, or above-ground sprayers. The flushing fluid is typically water
and may contain additives to improve contaminant removal.
The flushing fluid percolates through the contaminated soil,
removing contaminants as it proceeds. Contaminants are mobi-
lized by solubilization into the flushing fluid, formation of emul-
sions, or through chemical reactions with the flushing fluid [19].
Contaminated flushing fluid or leachate mixes with ground-
water and is collected (2) for treatment. The flushing fluid
delivery and the groundwater extraction systems are designed
to ensure complete contaminant recovery [7]. Ditches open to
the surface, subsurface collection drains, or groundwater recov-
ery wells may be used to collect flushing fluids and mobilized
contaminants. Proper design of a fluid recovery system is very
important to the effective application of soil flushing.
Contaminated groundwater and flushing fluids are cap-
tured and pumped to the surface in a standard groundwater
extraction well (3). The rate of groundwater withdrawal is
determined by the flushing fluid delivery rate, the natural infil-
tration rate, and the groundwater hydrology. These will deter-
mine the extent to which the groundwater removal rate must
exceed the flushing fluid delivery rate to ensure recovery of all
reagents and mobilized contaminants. The system must be
designed so that hydraulic control is maintained.
The groundwater and flushing fluid are treated (4) using
the appropriate wastewater treatment methods. Extracted
groundwater is treated to reduce the heavy metal content,
organics, total suspended solids, and other parameters until
they meet regulatory requirements. Metals may be removed
by lime precipitation or by other technologies compatible with
the flushing reagents used. Organics are removed with acti-
vated carbon, air stripping, or other appropriate technologies.
Whenever possible, treated water should be recycled as makeup
water at the front end of the soil-flushing process.
Flushing additives (5) are added, as required, to the
treated groundwater, which is recycled for use as flushing
fluid. Water alone is used to remove hydrophilic organics and
soluble heavy-metal salts [9]. Surfactants may be added to
remove hydrophobic and slightly hydrophilic organic con-
taminants [12]. Chelating agents, such as ethylene-
diaminetetra-acetic acid (EDTA), can effectively remove cer-
tain metal compounds. Alkaline buffers such as tetrasodium
pyrophosphate can remove metals bound to the soil organic
fraction. Reducing agents such as hydroxylamine hydrochlo-
ride can reduce iron and manganese oxides that can bind
Figure 1
Schematic of Soil Flushing System
Spray Application
(1)
\ \ / /• \ \ / S
\ , / V i /
xn' *n'
fl J1_
Pum^
•}
Flushing
Additives
(5)
i3/
Groundwater
Treatment
(4)
(*/
^
pumf.
j
Groundwater '•
Extraction Well
(3) •:
Vadose
Zone
Leachate
Collection
(2)
i Groundwater
Zone
Low Permeability
Zone
Engineering Bulletin: In Situ Soil Flushing
-------
metals in soil. Insoluble heavy-metal compounds also can be
reduced or oxidized to more soluble compounds. Weak acid
solutions can improve the solubility of certain heavy metals
[9]. Treatability studies should be conducted to determine
compatability of the flushing reagents with the contaminants
and with the site soils.
Process Residuals
The primary waste stream generated is contaminated flush-
ing fluid, which is recovered along with groundwater. Recov-
ered flushing fluids may need treatment to meet appropriate
discharge standards prior to release to a local, publicly-owned
wastewater treatment works or receiving streams. To the maxi-
mum extent practical, this water should be recovered and
reused in the flushing process. The separation of surfactants
from recovered flushing fluid, for reuse in the process, is a major
factor in the cost of soil flushing. Treatment of the flushing fluid
results in process sludges and residual solids, such as spent
carbon and spent ion exchange resin, which must be appropri-
ately treated before disposal. Air emissions of volatile contami-
nants from recovered flushing fluids should be collected and
treated, as appropriate, to meet applicable regulatory standards.
Residual flushing additives in the soil may be a concern and
should be evaluated on a site-specific basis.
Site Requirements
Access roads are required for transport of vehicles to and
from the site. Stationary or mobile soil-flushing process systems
are located on site. The exact area required will depend on the
vendor system selected and the number of tanks or ponds
needed for washwater preparation and wastewater treatment.
Because contaminated flushing fluids are usually consid-
ered hazardous, their handling requires that a site safety plan be
developed to provide for personnel protection and special han-
dling measures during wastewater treatment operations. Fire
hazard and explosion considerations should be minimal, since
the soil-flushing fluid is predominantly water.
An Underground Injection Control (UIC) Permit may be
necessary if subsurface infiltration galleries or injection wells are
used. When groundwater is not recycled, a National Pollution
Discharge Elimination System (NPDES) or State Pollution Dis-
charge Elimination System (SPDES) permit may be required.
Federal, State, and local regulatory agencies should be con-
tacted to determine permitting requirements before imple-
menting this technology.
Slurry walls or other containment structures may be needed
along with hydraulic controls to ensure capture of contaminants
and flushing additives. Climatic conditions such as precipitation
cause surface runoff and water infiltration. Berms, dikes, or other
runoff control methods may be required. Impermeable mem-
branes may be necessary to limit infiltration of precipitation,
which could cause dilution of flushing solution and loss of hy-
draulic control. Cold weather freezing must also be considered
for shallow infiltration galleries and above-ground sprayers.
Performance Data
Some of the data presented for specific contaminant re-
moval effectiveness were obtained from publications devel-
oped by the respective soil-flushing-system vendors. The qual-
ity of this information has not been determined; however it
does give an indication of the effectiveness of in situ soil
flushing.
Tetrachloroethylene was discharged into the aquifer at the
site of a spill in Sindelfingen, Germany. The contaminated
aquifer is a high-permeability (k=5.10 x 10-4 m/sec) layer over-
laying a clay barrier. Soil flushing was accomplished by infiltrat-
ing water into the ground through ditches. The leaching liquid
and polluted groundwater were pumped out of eight wells and
treated with activated carbon. The treated water was recycled
through the infiltration ditches. Within 18 months, 17 metric
tons of chlorinated hydrocarbons were recovered [19, p. 565].
Two percolation basins were installed to flush contami-
nated soil at the United Chrome Products site near Corvallis,
Oregon. Approximately 1,100 tons of soil containing the
highest chromium concentrations were excavated and dis-
posed of offsite. The resulting pits from the excavations were
used as infiltration basins to flush the remaining contaminated
soil. The soil-flushing operation for the removal of hexavalent
chromium from an estimated 2.4 million gallons of contami-
nated groundwater began in August 1988. No information on
the site soils was provided, but preliminary estimates were that
a groundwater equilibrium concentration of 100 mg/Lchromium
would be reached in 1 to 2 years, but that final cleanup to 10
mg/L would take up to 25 years [20, p. H-1]. Since that time
over 8-million gallons of groundwater, containing over 25,000
pounds of chromium, have been removed from the 23 extrac-
tion wells in the shallow aquifer. Average monthly chromium
concentrations in the groundwater decreased from 1,923 mg/
L in August 1988 to 96 mg/L in March 1991 [4].
Waste-Tech Services, Inc. performed two tests of soil-
flushing techniques to remove creosote contamination at the
Laramie Tie Plant site in Wyoming. The first test involved slowly
flooding the soil surface with water to perform primary oil
recovery (POR). Soil flushing reduced the average concentra-
tion of total extractable organics (TEO) from an estimated
initial concentration of 93,000 mg/kg to 24,500 mg/kg, a 74
percent reduction. The second test involved sequential treat-
ment with alkaline agents, polymers, and surfactants. During
the 8-month treatment period, average TEO concentrations
were reduced to 4,000 mg/kg. This represents an 84 percent
reduction from the post-POR concentration (24,500 mg/kg)
and a 96 percent reduction from the estimated initial concen-
tration (93,000 mg/kg). The tests were performed in alluvial
sands and gravels. The low permeability of adjacent silts and
clays precluded soil flushing [22].
Laboratory tests were conducted on contaminated soils
from a fire-training area at Volk Air Force Base. Initial
concentrations of oil and grease in the soils were reported to be
10,000 and 6,000 mg/kg. A1.5-percent surfactant solution in
water was used to flush soil columns. The tests indicated that
75 to 94 percent of the initial hydrocarbon contamination
could be removed by flushing with 12-pore volumes of liquid.
Engineering Bulletin: In Situ Soil Flushing
-------
However, field tests were unsuccessful in removing the same
contaminants. Seven soil-flushing solutions, including the solu-
tion tested in the laboratory studies, were tested in field studies.
The flushing solutions were delivered to field test cells measur-
ing 1 foot deep and 1 to 2 feet square. Only three of the seven
tests achieved the target delivery of 14-pore volumes. Two of
the test cells plugged completely, permitting no further infiltra-
tion of flushing solutions. There was no statistically significant
removal of soil contaminants due to soil flushing. The plugging
of test cells may be related to the use of a surfactant solution.
By hydrolyzing in water, surfactants may block soil pores by
forming either floes or surfactant aggregates called micelles. In
addition, if the surfactant causes fine soil particles to become
suspended in the flushing fluid, narrow passages between soil
particles could be blocked. If enough of these narrow passages
are blocked along a continuous front, a "mat" is said to have
formed, and fluid flow is halted in that area [23] [7].
Resource Conservation Recovery Act (RCRA) Land Dis-
posal Restrictions (LDRs) that require treatment of wastes to
best demonstrated available technology (BOAT) levels prior to
land disposal may sometimes be determined to be applicable
or relevant and appropriate requirements (ARARs) for CERCLA
response actions. The soil-flushing technology can produce a
treated waste that meets treatment levels set by BOAT, but
may not reach these treatment levels in all cases. The ability
of the technology to meet required treatment levels is depen-
dent upon the specific waste constituents and the waste
matrix. In cases where soil flushing does not meet these
levels, it still may, in certain situations, be selected for use at
the site if a treatability variance establishing alternative treat-
ment levels is obtained. EPA has made the treatability vari-
ance process available in order to ensure that LDRs do not
unnecessarily restrict the use of alternative and innovative
treatment technologies. Treatability variances may be justi-
fied for handling complex soil and debris matrices. The
following guides describe when and how to seek a treatability
variance for soil and debris: Superfund LDR Guide #6A,
"Obtaining a Soil and Debris Treatability Variance for Reme-
dial Actions" (OSWER Directive 9347.3-06FS) [13], and Super-
fund LDR Guide #6B, "Obtaining a Soil and Debris Treatability
Variance for Removal Actions" (OSWER Directive 9347.3-07FS)
[14]. Another approach could be to use other treatment
techniques in conjunction with soil flushing to obtain desired
treatment levels.
Technology Status
In situ soil flushing is a developing technology that has had
limited application in the United States. In situ soil flushing
technology has been selected as one of the source control
remedies at the 12 Superfund sites listed in Table 3 [3].
EPA Contact
Technology-specific questions regarding soil flushing may
be directed to:
Michael Gruenfeld
U.S. EPA, Releases Control Branch
Risk Reduction Engineering Laboratory
2890 Woodbridge Avenue, Building 10
Edison, New Jersey 08837
Telephone FTS 340-6625 or (908) 321-6625.
Table 3
Superfund Sites Using In Situ Soil Flushing
Site
Byron Barrel & Drum
Goose Farm
Ljpari Landfill
Vineland Chemical
Harvey-Knott Drum
LA Clarke & Son
Ninth Avenue Dump
U.S. Aviex
South Calvacale Street
United Chrome Products
Cross Brothers Pail
Bog Creek Farm
Location (Region)
Cenesee County, NY (2)
Plumsted Township, N| (2)
Gloucester, N) (2)
Vineland, N| (2)
.DEm
Spotsytvania, VA (3)
Carry, IN (5)
Niles, Ml (5)
Houston, TX (6)
Corvallis, OR (10)
Pembroke, IL (5)
Howell Township, N| (2)
Primary Contaminants
VOCs (BTX, PCE, and TCE)
VOCs (Toluene, Ethylbenzene,
Oichloromethane, and TCE), SVOCs, and PAHs
VOCs (Benzene, Ethylbenzene, Dichlormethane,
and TCE), SVOCs, PAHs and Chlorinated ethers
(bis-2-chloroethylether)
Arsenic and VOCs (Dichloromethane)
Lead
Creosote, PAHs, and Benzene
VOCs (BTEX, TCE), PAHs, Phenols, Lead, PCBs,
and Total Metals
VOCs (Carbon Tetrachloride, OCA,
Ethylbenzene, PCE, TCE, Toluene, TCA, Freon,
Xytene, and Chloroform)
PAHs
Chromium
VOCs (Benzene, PCE, TCE, Toluene, and
Xytenes) and PCBs
VOCs, Organic*
Status
Pre-design: finalizing workplan
In design: 30% design phase
Operational, summer '91
Pre-design
In design: re-evaluating alternative
In design
In design: pilot failed
Pre-design: re-evaluating alternatives
In design
Operational since 8/88
In desgn: developing workplan
In design: treatment plant completed,
dump and treat not installed
Engineering Bulletin: In Situ Soil Flushing
-------
Acknowledgments
This bulletin was prepared for the U.S. Environmental Protec-
tion Agency, Office of Research and Development (ORD), Risk
Reduction Engineering Laboratory (RREL), Cincinnati, Ohio, by
Science Applications International Corporation (SAIC) under con-
tract No. 68-C8-0062. Mr. Eugene Harris served as the EPA
Technical Project Monitor. Mr. Gary Baker was SAIC's Work As-
signment Manager. This bulletin was authored by Mr. Jim Rawe of
SAIC. The author is especially grateful to Ms. Joyce Perdek of EPA,
RREL, who has contributed significantly by serving as a technical
reviewer during the development of this document.
The following other Agency and contractor personnel have
contributed their time and comments by participating in the
expert review meeting and/or peer reviewing the document:
Mr. Benjamin Blaney
Ms. Sally Clement
Mr. Clyde Dial
Ms. Linda Fiedler
Dr. David Wilson
EPA-RREL
Bruck, Hartman and Esposito
SAIC
EPA-TIO
Vanderbilt University
Ms. Tish Zimmerman EPA-OSWER
REFERENCES
1. Handbook: In Situ Treatment of Hazardous Waste-
Contaminated Soils. EPA/540/2-90/002, U.S. Environ-
mental Protection Agency, 1990.
2. A Compendium of Technologies Used in the Treatment
of Hazardous Wastes. EPA/625/8-87/014, U.S. Environ-
mental Protection Agency, 1987.
3. Innovative Treatment Technologies: Semi-Annual Status
Report. EPA/540/2-91/001, U.S. Environmental Protec-
tion Agency, 1991.
4. Personal communications of SAIC staff with RPMs, 1991.
5. In Situ Containment/Treatment System, Fact Sheet. U.S.
Environmental Protection Agency, 1988.
6. Sanning, D. E., et. al. Technologies for In Situ Treatment
of Hazardous Wastes. EPA/600/D-87/014, U.S. Environ-
mental Protection Agency, 1987.
7. Nash, |. and R.P. Traver. Field Evaluation of In Situ
Washing of Contaminated Soils With Water/Surfactants.
Overview-Soils Washing Technologies For: Comprehen-
sive Environmental Response, Compensation, and Liability
Act, Resource Conservation and Recovery Act, Leaking
Underground Storage Tanks, Site Remediation, U.S.
Environmental Protection Agency, 1989. pp. 383-392.
8. Wilson, D.)., et. al., Soil Washing and Flushing With
Surfactants. Tennessee Water Resources Research Center.
September, 1990.
9. Ellis, W.D., T.R. Fogg and A.N. Tafuri. Treatment of Soils
Contaminated With Heavy Metals. Overview-Soils
Washing Technologies For Comprehensive Environmen-
tal Response, Compensation, and Liability Act, Resource
Conservation and Recovery Act, Leaking Underground
Storage Tanks, Site Remediation, U.S. Environmental
Protection Agency, 1989. pp. 127-134.
10. Technology Screening Guide for Treatment of CERCLA
Soils and Sludges. EPA/540/2-88/004, U.S. Environmen-
tal Protection Agency, 1988.
11. Nunno, T.J., |.A. Hyman, and T. Pheiffer. Development of
Site Remediation Technologies in European Countries.
Presented at Workshop on the Extractive Treatment of
Excavated Soil. U.S. Environmental Protection Agency,
Edison, New jersey, 1988.
12. Ellis, W.D., J.R. Payne, and G.D. McNabb, Project
Summary: Treatment of Contaminated Soils with
Aqueous Surfactants. EPA/600/S2-85/129, U.S. Environ-
mental Protection Agency, 1985.
13. Superfund LDR Guide #6A: Obtaining a Soil and Debris
Treatability Variance for Remedial Actions. OSWER
Directive 9347.3-06FS, U.S. Environmental Protection
Agency, 1989.
14. Superfund LDR Guide #6B: Obtaining a Soil and Debris
Treatability Variance for Removal Actions. OSWER
Directive 9347.3-07FS, U.S. Environmental Protection
Agency, 1989.
15. Sims, R.C. Soil Remediation Techniques at Uncontrolled
Hazardous Waste Sites, A Critical Review. Air & Waste
Management Association, 1990.
16. Guide for Conducting Treatability Studies Under CERCLA,
Interim Final. EPA/540/2-89/058, U.S. Environmental
Protection Agency, 1989.
17. Connick, C.C. Mitigation of Heavy Metal Migration in
Soil. Overview-Soils Washing Technologies For: Compre-
hensive Environmental Response, Compensation, and
Liability Act, Resource Conservation and Recovery Act,
Leaking Underground Storage Tanks, Site Remediation,
U.S. Environmental Protection Agency, 1989. pp. 155-
165.
Engineering Bulletin: In Situ Soil Flushing
-------
18. Handbook: Remedial Action at Waste Disposal Sites
(Revised). EPA/625/6-85/006. U.S. Environmental
Protection Agency, 1985.
19. Stief, K. Remedial Action for Groundwater Protection
Case Studies Within the Federal Republic of Germany.
Presented at the 5th National Conference on Manage-
ment of Uncontrolled Hazardous Waste Sites.
Washington, DC., 1984.
20. Young, C, et. al. Innovative Operational Treatment
Technologies for Application to Superfund Site - Nine
Case Studies, Final Report. EPA 540/2-90/006, U.S.
Environmental Protection Agency, 1990.
21. United Chrome Groundwater Extraction and Treatment
Facility. Monthly Report - March 1991. U.S. Environ-
mental Protection Agency, Region 10, 1991.
22. Marketing Brochure, Waste-Tech Services, Inc., Waste
Minimization Division, 1990.
23. Sale, T. and M. Pitts. Chemically Enhanced In Situ Soil
Washing. Proceedings of the Conference on Petroleum
Hydrocarbons and Organic Chemicals in Ground Water:
Prevention, Detection and Restoration. National Water
Well Association, 1989.
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati, OH 45268
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use $300
-------
&EPA
United Statas
Environmental Protection
Agency
Office of Emergency and
Remedial Response
Washington. DC 20460:!
Of fee of
Research and Development
Cincinnati, OH 45268
Superfund
EPA/540/2-90/017
September 1990
Engineering Bulletin
Soil Washing Treatment
Purpose
Section 121(b) of the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA) mandates
the Environmental Protection Agency (EPA) to select remedies
that "utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the maximum
extent practicable' and to prefer remedial actions in which
treatment "permanently and significantly reduces the volume,
toxicity, or mobility of hazardous substances, pollutants, and
contaminants as a principal element* The Engineering Bulletins
are a series of documents that summarize the latest information
available on selected treatment and site remediation
technologies and related issues. They provide summaries of
and references for the latest information to help remedial
project managers, on-scene coordinators, contractors, and
other site cleanup managers understand the type of data and
site characteristics needed to evaluate a technology for potential
applicability to their Superfund or other hazardous waste site.
Those documents that describe individual treatment
technologies focus on remedial investigation scoping needs.
Addenda will be issued periodically to update the original
bulletins.
Abstract
Soil washing is a water-based process for mechanically
scrubbing soils ex-situ to remove undesirable contaminants.
The process removes contaminants from soils in one of two
ways: by dissolving or suspending them in the wash solution
(which is later treated by conventional wastewater treatment
methods) or by concentrating them into a smaller volume of
soil through simple particle size separation techniques (similar
to those used in sand and gravel operations). Soil washing
systems incorporating both removal techniques offer the greatest
promise for application to soils contaminated with a wide
variety of heavy metal and organic contaminants.
The concept of reducing soil contamination through the
use of particle size separation is based on the finding that most
organic and inorganic contaminants tend to bind, either
chemically or physically, to clay and silt soil particles. The silt
and clay, in turn, are attached to sand and gravel particles by
physical processes, primarily compaction and adhesion.
Washing processes that separate the fine (small) day and silt
particles from the coarser sand and gravel soil particles effectively
separate and concentrate the contaminants into a smaller
volume of soil that can be further treated or disposed. The
clean, larger fraction can be returned to the site for continued
use. This set of assumptions forms the basis for the volume-
reduction concept upon which most soil washing technology
applications, are being developed.
At the present time, soil washing is used extensively in
Europe and has had limited use in the United States. During
1986-1989, the technology was one of the selected source
control remedies at eight Superfund sites.
The final determination of the lowest cost alternative will
be more site-specific than process equipment dominated.
Vendors should be contacted to determine the availability of a
unit for a particular site. This bulletin provides information on
the technology applicability, the types of residuals resulting
from the use of the technology, the latest performance d2U,
site requirements, the status of the technology, and where to
go for further information.
Technology Applicability
Soil washing can be used either as a stand-alone technology
or in combination with other treatment technologies. In some
cases, the process can deliver the performance needed to
reduce contaminant concentrations to acceptable levels and,
thus, serve as a stand-alone technology. In other cases, soil
washing is most successful when combined with other
technologies. It can be cost-effective as a pre-processing step
in reducing the quantity of material to be processed by another
technology such as incineration; it also can be used effectively
to transform the soil feedstock into a more homogeneous
condition to augment operations in the subsequent treatment
system. In general, soil washing is effective on coarse sand and
gravel contaminated with a wide range of organic, inorganic,
and reactive contaminants. Soils containing a large amount of
clay and silt typically do not respond well to soil washing,
especially if it is applied as a stand-alone technology.
A wide variety of chemical contaminants can be removed
from soils through soil washing applications. Removal efficiencies
depend on the type of contaminant as well as the type of soil.
Volatile organic contaminants often are easily removed from
soil by washing; experience shows thatvolatiles can be removed
with 90-99 percent efficiency or more. Semivolatile organics
-------
may be removed to a lesser extent (40-90 percent) by selection
of the proper surfactant. MeUls and pesticides, which are more
insoluble in water, often require acids or cheating agents for
successful soil washing. The process can be applicable for the
treatment of soils contaminated with specific listed Resource
Conservation and Recovey Act (RCRA) wastes and other
hazardous wastes including wood-preserving chemicals
(pentachlorophenol, creosote), organic solvents, electroplating
residues (cyanides, heavy metals), paintsludges (heavy metals),
organic chemicals production residues, pesticides and pesticides
production residues, and petroleum/oil residues [1, p. 659][2,
p. 1S][4)[7 through 13]*.
The effectiveness of soil washing for general contaminant
groups and soil types is shown in Table 1 [1, p. 659][3, p.
13][15, p.1]. Examples of constituents within contaminant
groups are provided in Reference 3, Technology Screening
Guide For Treatment of CERQA Soils and Sludges.' This table
is based on currently available information or professional
judgment where definitive information is currently inadequate
or unavailable. The proven effectiveness of the technology for
a particular site or waste does not ensure that it will be effective
at all sites or that the treatment efficiency achieved will be
acceptable atothersites. For the ratings used in this table, good
to excellent applicability means the probability is high that soil
TabJol
Applicability of SoU Washing on General Contaminant
Groups for Various Soils
Contaminant Croups
w
1^
a
1
I
Keactht
m <
T
O 1
Halogenated volatile*
Halogenated semivolatiles
Nonhalogenated volatile!
Nonhalogenated semrvolatiles
PCBs
Pesticides (halogenated)
Dfexins/Furans
Organic cyanides
Organic corrosives
Volatile metals
Nonvolatile metals
Asbestos
Radioactive materials
Inorganic corrosives
Inorganic cyanides
OxidUen
Reducers
succettful
Mot Appfcabte: Expert opinion out tee
Matrix
Sandy/ tf (y/C/ay
Cfovitly Soils Soils
m
T
•
T
T
T
T
T
. T
•
a
T
T
T
T
T
robtbifity (hat to
vdMcarainchoa
hnotogy vriB not
T
T
T
T '
T
T
T
T
T
T
T
a
T
T
T
T
T
•Ing technology
work
washing will be effective for that particular contaminant and
matrix. Moderate to marginal applicability indicates situations
where care needs to be exercised in choosing the soil washing
technology. When not applicable is shown, the technology will,
probably not work for that particular combination of contaminant!
group and matrix. Other sources of general observations and
average removal efficiencies for different trealability groups are
the Superfund LDR Guide #6A, 'Obtaining a Soil and Debris
Treatability Variance for Remedial Actions' (OSWER Directive
9347.3-06FS), [16] and Superfund LDR Guide #6B, 'Obtaining
a Soil and Debris Treatability Variance for Removal Actions'
(OSWER Directive 9347.3-07FS) [17J.
Information on cleanup objectives as well as the physical
and chemical characteristics of the site soil and its contaminants
is necessary to determine the potential performance of this
technology and the requirements for waste preparation and
pretreatment. Treatability tests are also required at th e laboratory
screening, bench-scale and/or pilot-scale level(s) to determine
Table 2
Waste Soil Characterization Parameters
> [nr«nnc« numbar. 0*9* numb*]
Parameter
Kev Physical
Purpose and Comment
Partide size distribution:
>2mm
0.25-2 mm
0.061-0.25 mm
<0.063 mm
Oversize pretreatment requirements
Effective soi washing
Limited sol washing
Oay and silt fraction—difficult soil
washing
Other Physical
Type, phydcal form,
handling properties
Moisture content
Key Chemical
Organic
Concentration
Volatility
Partition
coefficient
Metals
Humlcadd
Other Chemical
pH, buffering
capacity
Affects pretreatment and transfer
requirement!
Affects pretreatment and transfer
requirements
Determine contaminants and assess
separation and washing efficiency,
hydrophobic interaction, washing
Bud compatibility, changes in
washing fluid with changes in
contaminants. May require
preblending for consistent feed. Use
the jar test protocol to determine
contaminant partitioning.
Concentration and species of
constituents (specific jar test) wiD
determine washing fluid compatibility,
mobility of metals, posttreatmenc.
Organic content wii affect adsorption
characteristics of contaminants on sod.
Important In marine/wetland sites.
May affect pretreatment
requirements, compatibility with
equipment materials of construction,
wash fluid compatibility.
Engineering Bulletin: Soil Washing Treatment
-------
figure 1
Soil Washing Applicable Particle Size Range
Sand
Average • Large
Gravel
Avenge t Large
Soil Washing
(Regime III)
Soil Wash with
Specific Washing Fluid
(Regime II)
Economic Wash
with Simple Particle
Size Separation
(Regime I)
0.001 0.002 0.006 0.01 0.02
0.063 0.1 0.2 0.6 1 2
Diameter of Particle in Millimeters
the feasibility of the specific soil washing process being
considered and to understand waste preparation and
pretreatrnent steps needed at a particular site. If bench-test
resultsarepremising,pilot-scaledemonstrations should normally
be conducted before final commitment to full-scale.
implementation. Treatability study procedures are explained
in the EPA's forthcoming document entitled "Superfund
Treatability Study Protocol: Bench-Scale Level of Soils Washing
for Contaminated Soils' [14].
Table 2 contains physical and chemical soil characterization
parameters that must be established before a treatability test is
conducted on a specific soil washing process. The parameters
are defined as either "key* or "other' and should be evaluated
on a site-specific basis. Key parameters represent soil
characteristics that have a direct impact on the soil washing
process. Other parameters should also be determined, but they
can be adjusted prior to the soil washing step based on specific
process requirements. The table contains comments relating to
the purpose of the specific parameter to be characterized and
its impact on the process [6, p. 90][14, p. 35].
Particle size distribution is the key physical parameter for
determining the feasibility of using a soil washing process.
Although particle size distribution should not become the sole
reason for choosing or eliminating soil washing as a candidate
technology for remediation, it can provide an initial means of
screening for the potential use of soil washing. Figure 1
presents a simplistic particle size distribution range of curves
that illustrate a general screening definition for soil washing
technology.
In its simplest application, soil washing is a particle size
separation process that can be used to segregate the fine
fractions from the coarse fractions. In Regime I of Figure 1,
where coarse soils are found, the matrix is very amenable to soil
washing using simple particle size separation.
Most contaminated soils will have a distribution that falls
within Regime II of Figure 1. The types of contaminants found
in the matrix will govern the composition of the washing fluid
and the overall efficiency of the soil washing process.
In Regime III of Figure 1, soils consisting largely of finer
sand, silt, and clay fractions, and those with high humic
content, tend to contain strongly adsorbed organics that
generally do not respond favorably to systems that work by only
dissolving or suspending contaminants in the wash solution.
However, they may respond to soil washing systems that also
incorporate apartidesizeseparation step whereby contaminants
can be concentrated into a smaller volume.
Limitations
Contaminants in soils containing a high percentage of silt-
and day-sized particles typically are strongly adsorbed and
difficult to remove. In such cases, soil washing generally should
not be considered as a stand-alone technology.
Hydrophobic contaminants generally require surfactants
or organic solvents for their removal from soil. Complex
mixtures of contaminants in the soil (such as a mixture of
metals, nonvolatile organics, and semivolatile organics) and
Engineering Bulletin: Soil Washing Treatment
-------
RguroZ
Aqueous Soil Washing Proems
Volatile
Contaminated
Soil
Makeup water
Extracting Agent(s)
(Surfactants, etc.)
Soil
Preparation
0)
Prepared
Soil
Soil Washing
Process
(2)
-Washing
-dinting
-Size Separation
Emission
Control
Treated
Air Emissions
Recycled water
Chemicals
Slowdown
Water
Wastewater
Treatment
(3)
Treated
Water
Sludges/
Contaminated Fines
Qean Soil
Oversized Rejects
frequent changes in the contaminant composition in the soil
matrix make it difficult to formulate a single suitable washing
fluid that will consistently and reliably remove all of thedifferent
types of contaminants from the soil particles. Sequential
washing steps may be needed. Frequent changes in the wash
formulation and/or the soil/wash fluid ratio may be required [3,
p. 761114, p. 7].
While washwater additives such as surfactants and chelants
may enhance some contaminant removal efficiencies in the soil
washing portion of the process, they also tend to interfere with
the downstream wastewatertreatmentsegments of the process-.
The presence of these additives in the washed soil and in the
wastewater treatment sludge may cause some difficulty in their
disposal (14, p. 7][15, p. 1 ]. Costs associated with handling the
additives and managing them as part of the residuals/wastewater
streams must be carefully weighed against the incremental
improvements in soil washing performance that they may
provide.
Technology Description
Figure 2 Is a general schematic of the soil washing process
[l,P.6S7][3,p.72][1S.p.1].
Soil preparation (1) includes the excavation and/or moving
of contaminated soil to the process where it is normally
screened to remove debris and large objects. Depending upon
the technology and whether the process is semibatch or
continuous, the soil may be made pumpable by the addition of
water.
A number of unit processes occur in the soil washing
process (2). Soil is mixed with washwater and possibly extraction
agents) to remove contaminants from soil and transfer them
to the extraction fluid. The soil and washwater are then
separated, and the soil is rinsed with clean water. Gean soil is
then removed from the process as product. Suspended soil
particles are recovered directly from the spent washwater, as
sludge, bygravity means, or they may be removed by fkxculation
with a selected polymer or chemical, and then separated by
gravity. These solids will most likely be a smaller quantity but
carry higher levels of contamination than the original soil and,
therefore, should be targeted for either further treatment or
secure disposal. Residual solids from recycle water cleanup may
require post-treatment to ensure safe disposal or release. Water
used in the soil washing process is treated by conventional^
wastewater treatment processes to enable it to be recycled fo m
further use.
Engineering Bulletin: Soil Washing Treatment
-------
Wastewater treatment (3) processes the blowdown or
discharge water to meet regulatory requirements for heavy
metal content, organics, total suspended solids, and other
parameters. Whenever possible, treated water should be
recycled to the soil washing process. Residual solids, such as
spent ion exchange resin and carbon, and sludges from biologi-
cal treatment may require post-treatment to ensure safedisposal
or release.
Vapor treatment may be needed to control air emissions
from excavation, feed preparation, and extraction; these
emissions are collected and treated, normally by carbon
adsorption or incineration, before being released to the
atmosphere.
Process Residuals
There are four main waste streams generated during soil
washing: contaminated solids from the soil washing unit,
wastewater, wastewater treatment sludges and residuals, and
air emissions.
Contaminated clay fines and sludges resulting from the
process may require further treatment using acceptable
treatment technologies (such as incineration, low temperature
desorption, solidification and stabilization, biological treatment,
and chemical treatment) in order to permit disposal in an
environmentally safe manner [16]. Blowdown water may need
treatment to meet appropriate discharge standards prior to
release to a local, publicly owned wastewater treatment works
or receiving stream. To the maximum extent practical, this
water should be recovered and reused in the washing process.
The wastewater treatment process sludges and residual solids,
such as spent carbon and spent ion exchange resin, must be
appropriately treated before disposal. Any air emissions from
the waste preparation area or the washing unit should be
collected and treated, as appropriate to meet applicable
regulatory standards.
Site Requirements
Access roads are required for transport of vehicles to and
from the site. Typically, mobile soil washing process systems
are located onsite and may occupy up to 4 acres for a 20 ton/
hour unit; the exact area will depend on the vendor system
selected, the amount of soil storage space, and/or the number
of tanks or ponds needed for washwater preparation and
wastewater treatment.
Typical utilities required are water, electricity, steam, and
compressed air. An estimate of the net (consumed) quantity of
local water required for soil washing, assuming water cleanup
and recirculation, is 130,000-800,000 gallons per 1,000 cubic
yards (2PSOO,OOp IDS.) of soil (approximately 0.05-0.3 gallons
per pound).
Because contaminated soils are usually considered
hazardous, their handling requires that a site safety plan be
developed to provide for personnel protection and special
handling measures during soil washing operations.
Moisture content of soil must be controlled for consistent
handling and treatment; this can be accomplished, in part, by
covering excavation, storage, and treatment areas.
Fire hazard and explosion considerations should be minimal,
since the soil washing fluid is predominantly water. Generally,
soil washing does not require storing explosive, highly reactive
materials.
Climatic conditions such as annual orseasonal precipitation
cause surface runoff and water infiltration. B«rms, dikes, or
other runoff control methods may be required. Cold weather
freezing must also be considered for aqueous systems and soil
excavation operations.
Proximity to a residential neighborhood will affect plant
noise requirements and emissions permitted in order to minimize
their impact on the population and meet existing rules and
regulations.
If all or part of the processed soil is to be redeposited at the
site, storage area* must be provided until analytical data are
obtained that verifies that treatment standards have been
achieved. Onsite analytical capability could expedite the
storage/final disposition process. However, soil washing might
be applied to many different contaminant groups. Therefore,
the analytes that would have to be determined are site specific,'
and the analytical equipment that must be available will vary
from site to site.
Performance Data
The performances of soil washing processes currently
shown to be effective in specific applications are listed in Table
3 [1][2][4][7 through 13]. Also fisted are the range of particle
size treated, contaminants successfully extracted, byproduct
wastes generated, extraction agents used, major extraction
equipment for each system, and general process comments.
The data presented for specific contaminant removal
effectiveness were obtained from publications developed by
the respective soil washing system vendors. The quality of this
information has not been determined.
*
RCRA Land Disposal Restrictions (LORs) that require
treatmentof wastes to best demonstrated available technology
(BOAT) levels prior to land disposal may sometimes be
determined to be applicable or relevant and appropriate
requirements (ARARs) for CERCLA response actions. The soil
washing technology can produce a treated waste that meets
treatment levels set by BOAT, butmaynotreach these treatment
levels in all cases. The ability to meet required treatment levels
is dependent upon the specific waste constituents and the
waste matrix. In cases where soil washing does not meet these
levels, it still may, in certain situations, be selected for use at the
site if a treatability variance establishing alternative treatment
levels is obtained. EPA has made the treatability variance
process available in order to ensure that LORs do not
unnecessarily restrict the use of alternative and innovative
treatment technologies. Treatability variances may be justified
for handling complex soil and debris matrices. The following
guidesdescribewhen and how to seeka treatability variance for
soil and debris: Superfund LDR Guide #6A, "Obtaining a Soil
Engineering Bulletin: Soil Washing Treatment
-------
and Debris Treatability Variance for Remedial Actions' (OSWER
Directive 9347.3-06FS) [16], and Superfund LDR Guide #68,
"Obtaining a Soil and Debris Treatability Variance for Removal
Actions' (OSWER Directive 9347.3-07FS) [17]. Another
approach could be to use other treatment techniques in series
with soil washing to obtain desired treatment levels.
Technology Status
During 1986-1989, soil washing technology was selected
as one of the source control remedies at eight Superfund sites:
Vineland Chemical, New jersey; Koppers Oroville Plant,
California; Cape Fear Wood Preserving, North Carolina; Ewan
Property, New Jersey; Tinkam Garage, New Hampshire; United
Scrap, Ohio; Koppers/Texarkana, Texas; and South Cavalcade,
Texas [18].
A large number of vendors provide a soil washing
technology. Table 3 shows the current jutuj of the technology
for 14 vendors. The front portion of the table indicates the scale
of equipment available from the vendor and gives some
indication of the vendor's experience by showing the year it
began operation.
Processes evaluated or used for site cleanups by the EPA are
identified separately by asterisks in the Proprietary Vendor
Process/EPA column in Table 3.
The following soil washing processes that are under
development have not been evaluated by the EPA or included
in Table 3. Environmental Croup, Inc of Webster, Texas, has
a process that reportedly removes metals and oil from soil.
Process efficiency is stated as greater than 99 percent for lead
removal from soils cleaned in Concord, California; greater than
99 percent for copper, lead, and zinc at a site in Racine,
Wisconsin; and 94 percent for PCB removal on a Morrison-
Knudsen Company project. The process does not appear to
separate soil into different size fractions. Detailed information
on the process is not available. Consolidated Sludge Company
of Cleveland, Ohio, has a soil washing system planned that
incorporates their Mega-sludge Press at the end of the process
for dewatering solids. The system has not yet been built.
Vendor-su pplied treatment costs of the processes reviewed
ranged from {20 to J205 per ton of feed soil. The upper end
of the cost range includes costs for soil residue disposal.
EPA Contact
Technology-specific questions regarding soil washing may
be directed to:
Michael Gruenfeld
U.S. EPA, Releases Control Branch
Risk Reduction Engineering Laboratory
Woodbridge Avenue, Building 10
Edison, New jersey 08837
Telephone FTS 340-6625 or (201) 321-6625.
Engineering Bulletin: Son Washing Treatment
-------
Table 3. Summary of Performance Data and Technology Status • Part I
[Proprietary Vendor
froccu/EM
HlghtX Stoic
of Operation
Ytar Operation
8*90/1
Hangt of Partlcl*
Size Treated
Contaminants
Extracted from Sol
Extraction Aotnt(i)
| U.S. Processes
(1) SOILCUIANING COMPANY
OF AMERICA [SID 3. p. 2]
(2Y BIOTROLSOILTREATMENT
SYSTEM (BSTS)
[4, P. 6111 2]
(3) EPA'S MOBILE COUNTER.
CURRENT EXTRACTOR
[9][S,p.S]
(4)* EPA'S FIRST GENERATION
PILOT DRUM SCREEN
WASHER [10, p. 8]
(5)' MTA REMEDIAL
RESOURCES
[11 HI 5, p. 2]
Full scale
IStons/hr
Pilot scale
SOO Ibs/hr
Pilot scale
4.1 tons/hr
Pilot scale
Bench scale
1988
Fall. 1987
Modified with
drum washer
and shakedown-
1982
Full Scale-1986
1988
N/A
Bulk so!
Above day size and
below 0.5 in. Some
cleaning of fine par-
tides In bio-reactor
2-25 mm in drum
washer
<2 mm in four-itage
extractor
Oversize (>2 mm)
removed prior to
treatment
Oversize removed
prior to treatment
Oil and grease
Organics • pentachloro>
phenol, creosote,
naphthalene, pyrene,
fluorene, etc.
Soluble organics
(phenol, etc.)
Heavy metals
(Pb, etc.)
Petroleum
hydrocarbons
Organics (oil)
Heavy metals (Inorganics]
removed using counter-
current decantation
with leaching
Hot water with
surfactant
Proprietary
conditioning
chemicals
Various solvents,
additives, surfactants,
redox acids and bases
delating agent
(EDTA)
Biodegradable
surfactant
(aqueous slurry)
Surfactants and
alkaline chemicals
added upstream of
froth flotation cells.
Acid for leaching.
Non-U.S. Processes i|
(«) ECOTECHNIEK8V
P. P- 17]
(7) BOOEMSANERINC
NEDERLANO
BV(BSN)
(2, p. 17]
(8) HARBAUER
P.P.20K7.P.S]
(9) HWZ
BOOEMSANERINC 8V
Rp.17]
(10) HEIIMAN
MIUEUTECHNIEK BV
[2.P.17][7,p.6]
(11) HE1DEMII FROTH
FLOTATION
C7.P.S]
Commercial
lOOton/hrmax
Commercial
20 ton/hr
Commercial
1S-20 tons/hr
Commercial
20*22 tons/hr
Pilot scale
1 0-1 S tons/hr
Full scale
1982
1982
Lab -1985
Commercial -1986
With fines
removal. 1987
1984
1985
N/A
Sandy soil
>100 mm removed
No more than 20%
<63pm
Sludge <30 pm not
deaned
1 S (im • Smm Pre-
treatment: coarse
screens, electromagnet
blade washer
<10 mm and >63 pm
<10 mm and no more
than 30% <63 \tm
<4 mm and no more
than 20% <50 \an
Crude oil
Oa from sandy soil
Mostly organics
Limited heavy metals
removal experience
Cyanide, Chlorinated
HC, some heavy
metals, PNA
Cyanide, heavy metals,
mineral oil (water
immiscible hydro-
carbons)
Cyanide, heavy metals,
chlorinated HCs. ofl,
toluene, benzene.
pesticides, etc.
None. Water-sand
slurry heated to 90*C
max. with steam.
None. Uses high
pressure water jet
for soils washing.
Hydraulically
produced oscillation/
vibration
Surfactants
Acid/base
Sodium Hydroxide
to adjust pH
Surfactants
Proprietary extraction
agents. Hydrogen
Peroxide (H,0,)
added to react
with extracted CN
to form CO, and NH,
Proprietary Surfact-
ants and other pro*
prietary chemicals
•Process evaluated or used for site deanup by the EPX N/A » Not available.
Engineering Bulletin: Soil Washing Treatment
-------
Tabte 3. Summary of Performance Data and Technology Status - Part I (continued)
Proprietary Vendor
Pneat/lPA
Highest Scale
of Operation
Year Operation
Began
Range of Particle
SUt Treated
Contaminants
Extracted From Sot
Extraction Agtnt(t)
Non U.S. Processes (continued)
(12) EWHALSEN-
BREITENBURG
Dekomat System [2, p. 20]
(13) TBSG
INDUSTRIEVEITIETUNCEN
O« Crep 1 System [7, p. 7]
(14) KLOCKNER
UMWELTECHNIK
jet-Modified BSN [2, p. 20]
Pilot scale
8*1 0 cu. m/hr
Pilot scale
Pilot scale
N/A
1986
N/A
<80 mm
Clays treated offsite
Sand <50 mm
Particles <1 00 jim
treated offsite
No more than 20%
<63 tun
Oil from sandy soil
Hydrocarbon and o3
Aliphatics and aromatic*
with densities < water,
volatile organio, some
other hydrocarbons
Proprietary
Proprietary combina-
tion of surfactants,
solvents, and aromatic
hydrocarbons
None. Soil blasted
with a water jet (at
5,075 psi)
Table 3. Summary of Performance Data and Technology Status - Part II
\ Proprietary Vendor
Pncess/lPA
Byproduct Wastes
Generated
Extraction
Equipment
efficiency el
Contaminant Removal
Additional
Process Comments
JU.S. Processes •
(1) SOIL CLEANING
OF AMERICA
(2)* 8IOTROLSOIL
TREATMENT SYSTEM
(BSTS)
(3) EPA'i MOBILE
COUNTCR-CURRENT
EXTRACTOR
(4)' EPA'sHRST
GENERATION PILOT
DRUM SCREEN
WASHER (POSW)
(5)' MTA REMEDIAL.
RESOURCES (MTARRQ
Froth Flotation
Wet oil
Oa and grease
Sludge from bio-
ogical treatment
Cay fraction
Recovered organic*
(extractor skimmings)
Spent
carbon (oversize)
Sludge'
Flocculated fines
FloccuUtion froth
Screw conveyors
Agitated
conditioning tank
Froth flotation
Slurry bioreactor
Drum screen
Water knife
Soil scrubber
4-Stage
Counter-current
chemical extractor
Drum screen
washer
Reagent blend
tank
Flotation cells
Counter-current
decantation
Contain- Removal Residual
leant Efficiency 9i ppm
OS and 5043 220-600
grease
For the case presented:
90-95% for Pentachlorophenol;
to residuals <1 1 5 ppm.
85-95% for most other organic*;
to residuals <1 ppm.
Co/warn- Removal Rtiiduai
inant Efficiency % ppm
Phenol 90 from in. soil >
80 from or. soil 96
AS,0, 50-30 0.5-1.3
toT Sift /to*
Contain- fraction Removal dual
inant mm Effc.% ppm
Oa and 0.25-2 99 <5
grease <0-25 90 2400
Contom- Removal Reiidual
inant Efficiency * ppm
Volatile
organic* 98-99+ < 50
SemivoUtile
organic* 98-99+ < 250
Most fuel
products 98-99+ < 2200
Three screw conveyors operated
In series, hot water with surfactant
injected Into each stage. Final soil
rinse on a fourth screw conveyor.
Dewatered days and organic] to be
treated offsite by Incineration,
solidification, etc. Washed soil was
appro*. 78% of feed. Therefore,
significant volume reduction was
achieved.
Cay fraction treated elsewhere.
Process removal efficiency
increases if extracting medium is
heated. Install wet classifiers
beneath the POSW to remove
waste water from treated soil.
Auger classifiers are required to
to discharge particles effectively.
Flotation cells linked by underflow
weir gates. Induced air blown
down a center shaft In each cell.
Continuous flow operation. Froth
contains 5-1 0 wt% of feed soil.
•Process evaluated or used for site cleanup by the EPA. N/A » Not available.
8
Engineering Bulletin: Soil Washing Treatment
-------
Table 3. Summary of Performance Data and Technology Status • Part II (continued)
Proprietary Vendor
ProttO/IM
Byproduct Waita
Generated
Extraction
Equipment
IdldtncYof
Contaminant Removal
Additional
Process CommenO
Non-U.S. Processes * |
(6) ECOTECHNIEK 8V
(7) 8OOEMSANERING
NEDERLAND 8V (BSN)
(8) HARBAUER
OF AMERICA
(9) HWZ
BOOEMSANERINC BV
(10) HEIIMAN
MIUEUTECHNIEK BV
(11) HE1DEMII FROTH
FLOTATION
(12) EWHALSEN-
BRETTIN8URG
Dekomat System
(13) TBSC
INOUSTRIEVEJnET.
UNCEN
Oi Crep 1 System
(14) KLOCXNER
UMWELTECHNIK
High Pressure Water
Jet-Modified BSN
Wet oil
Oa/organics
recovered from
wastewater fines
Carbon which may
contain contami-
nant!
Fines
Sludge containing
Iron cyanide
Large particles —
carbon, wood, grass
Flocculated fines
sludge
O3 (if any) and sat
Contaminated float
Recovered oil
Flocculated fines
(sludge)
03 phase contain-
ing OH Crep 1
Oa/organfcs
wastewater fines
Sludge
[acketed, agitated
tank
Water jet
Conditioning tank
Low frequency
vibration unit
Scrubber
(for caustic
addition)
Upflow classifier
Mix tank
followed by soils
fraction equip-
ment — hydro-
clones, sieves,
tat plate separators
Conditioning tank
Froth flotation
tanks
High-ihear
stirred tank
Screw mixer
followed by a
rotating separation
drum for oil
recovery
Water jet -
circular nozzie
arrangement
About 90%
20,000 ppm residual oil
Selected results:
Co/worn- Removal Reiiauol
inant Efficiency W ppm
Aromatics >£1 >45
PNAs 95 15
Crude oil 97 2300
Contain' Removal Residual
inant Efficiency % ppm
Orginic-Q NO
Tot. organic* 96 159-201
ToL phenol 86-94 7-22.5
PAH 86-90 91. -4-97.5
PCS 8448 0.5-1.3
Contom- Removal Residual
inant Efficiency 96 ppm
CN 9S 5-15
PNAs 98 15-20
Chlorin-HC 98 <1
Heavy metals 75 75-125
Co/warn- Removal Residual
inant Efficiency % ppm
Cyanide 93-99 <15
Heavy metal
cations approx. 70 <200
Contain- Removal Residual
inant Efficiency % ppm
Cyanide >9S ' 5
Heavy metals >90 avg >1 50
Chlorin-HC >99 OJ
Oil >99 20
About 95% oii removed
>95% Removal of hydrocarbons
has been achieved. Result! are
influenced by other contaminant]
present.
Selected results:
Contain- Removal Residual
inant Efficiency % ppm
HC 96.3 82.05
Chlorin-HC >?S. <0.01
Aromatics 99.8 <0.02
PAHS 95.4 15.48
Phenol >99.8 <0.01
Effectiveness of process depen-
dent on soil particle size and type
of oil to be separated.
No com menu
Vibrating screw conveyor used.
Cleaned soil separated from
extractant liquor in stages; coarse
soil by sedimentation, medium
fraction in hydrodone, fines
(1 5-20 jim) by vacuum filter press.
When the fines fraction (<63 pm) is
greater than 20%, the process is not
economical. HWZ has had some
problems in extracting PNAs and
oily material.
Process works best on sandy soils
with a minimum of humus-like
compounds. Because no sand or
charcoal filters ar« employed by
Heijmans, the system does not
remove contaminants such as
chlorinated hydrocarbons.
Process has broad application for
removing hazardous materials from
soil. Most experience has been on
a laboratory scale.
Cleaned soil from high shear
stirred tank is separated into
fractions using vibrating screens.
screw classifiers, hydroclones, and
sedimentation tanks.
03 Crep system was used success-
fully in Hamburg, FRC (in 1 986)
to remove PCBs, PAHs, and other
hydrocarbons.
No comments
•Process evaluated or used for site cleanup by the EPA. N/A • Not available.
Engineering Bulletin: Soil Washing Treatment
-------
REFERENCES
1. Assink,J.W. Extractive M«thod$ for Soil
Decontamination; a General Survey and Review of
Operational Treatment Installations. In: Proceedings
from the First International TNO Conference on
Contaminated Soil, Ultrecht, Netherlands, 1985.
2. Raghavan, It, D.H. Dietz, and L Coles. Cleaning
Excavated Soil Using Extraction Agents: A SUte-of-the-
Art Review. EPA 600/2-89/034, U.S. Environmental
Protection Agency, 1988.
3. Technology Screening Guide for Treatment of CERCLA
Soils and Sludges. EPA 540/2-88/004, U.S.
Environmental Protection Agency, 1988.
4. M.K. Stinson, et al. Workshop on the Extractive
Treatment of Excavated Soil. U.S. Environmental
Protection Agency, Edison, New jersey, 1988.
5. Smarkel, K.L Technology Demonstration Report - Soil
Washing of Low Volatility Petroleum Hydrocarbons.
California Department of Health Services, 1988.
6. Guide for Conducting Treatability Studies Under
CERCLA, Interim Final. EPA/540/2-89/058, U.S.
Environmental Protection Agency, 1989.
7. Nunno, T.J., J.A. Hyman, and T. Pheiffer. Development
of Site Remediation Technologies in European
Countries. Presented at Workshop on the Extractive
Treatment of Excavated Soil. U.S. Environmental
Protection Agency, Edison, New Jersey, 1988.
8. Nunno, T.)., and |X Hyman. Assessment of
International Technologies for Superfund Applications.
EPA/540/2-88/003, U.S. Environmental Protection
Agency, 1988.
9. Scholz, R., and J. Milanowski. Mobile System for
Extracting Spilled Hazardous Materials from Excavated
Soils, Project Summary. EPA/600/52-83/100, U.S.
Environmental Protection Agency, 1983.
10. Nash,]. Field Application of Pilot Scale Soils Washing
System. Presented at Workshop on the Extracting
Treatment of Excavated Soil. U.S. Environmental
Protection Agency, Edison, New Jersey, 1988.
11. Trost, P J., and RJ. Rkkard. On-site Soil Washing—A
Low Cost Alternative. Presented at ADPA. Los Angeles,
California, 1987.
12. Pflug, A.D. Abstract of Treatment Technologies, Biotrol,
Inc. Chaska, Minnesota, (no date).
13. Biotrol Technical Bulletin, No. 87-1 A, Presented at
Workshop on the Extraction Treatment of Excavated
Soil, UJ. Environmental Protection Agency, Edison,
New Jersey, 1988.
14. Superfund Treatability Study Protocol: Bench-Scale
Level of Soils Washing for Contaminated Soils, Interim
Report. U.S. Environmental Protection Agency, 1989.
15. Innovative Technology: Soil Washing. OSWER Directive
9200.5-250FS, U.S. Environmental Protection Agency,
1989.
16. Superfund LDR Guide #6A: Obtaining a Soil and Debris
Treatability Variance for Remedial Actions. OSWER
Directive 9347.3-06FS, U.S. Environmental Protection
Agency, 1989.
17. Superfund LDR Guide #68: Obtaining a Soil and Debris
Treatability Variance for Removal Actions. OSWER
Directive 9347.3-07FS, U.S. Environmental Protection
Agency, 1989.
18. ROD Annual Report, FY1989. EPA/540/8.90/006, U.S.
Environmental Protection Agency, 1990.
OTHER REFERENCES
Overview Soils Washing Technologies For
Comprehensive Environmental Response,
Compensation, and liability Act, Resource Conservation
and Recovery Act, Leaking Underground Storage Tanks,
Site Remediation, U.S. Environmental Protection
Agency, 1989.
W
Engineering Bulletin: Soil Washing Treatment
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Engineering Bulletin: Soil Wasting Treatment 1 I
-------
United States Center for Environmental Research BULK RATE
Environmental Protection Information POSTAGE & FEES PAID
Agency Cincinnati, OH 45268 EPA
PERMfT No. C-3S
Official Business
Penalty for Private Use $300
-------
&EPA
United States
Environmental Protection
Agency
Office of
Solid Waste and
Emergency Response
EPA/540/2-91/020B
September 1991
Guide for Conducting Treatability
Studies under CERCLA:
Soil Washing
Office of Emergency and Remedial Response
Hazardous Site Control Division OS-220
QUICK REFERENCE FACT SHEET
Section 121 (b) of CERCLA mandates that EPA should select remedies that "utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the maximum extent practicable" and that EPA should prefer remedial actions in
which treatment that "permanently reduces the volume, toxicity, or mobility of hazardous substances, pollutants, and contaminants is
a principal element" Treatability studies provide data to support treatment technology selection and remedy implementation and
should be performed as soon as it is evident that insufficient information is available to ensure the quality of the decision. Conducting
treatability studies early in the remedial investigation/feasibility study (RI/FS) process should reduce uncertainties associated with
selecting the remedy, and provide a sounder basis for the ROD. Regional planning should factor in the time and resources required for
these studies.
This fact sheet provides a summary of information to facilitate the planning and execution of soil washing remedy selection
treatability studies in support of the RI/FS and the remedial design/remedial action (RD/RA) processes. This fact sheet follows the
organization of the "Guide for Conducting Treatability Studies Under CERCLA: Soil Washing," Interim Guidance, EPA/540/OOO/OOOA
September 1991. Detailed information on designing and implementing remedy selection treatability studies for soil washing is
provided in the guidance document
INTRODUCTION
There are three levels or tiers of treatability studies: rem-
edy screening, remedy selection, and remedy design. The
"Guide for Conducting Treatability Studies Under CERCLA Soil
Washing Remedy Selection" discusses .the remedy screening
and remedy selection levels.
Remedy screening studies are designed to provide a quick
and relatively inexpensive indication of whether soil washing is
a potentially viable remedial technology. Soil washing remedy
screening studies should not be the only level of testing per-
formed before final remedy selection. Remedy selection and
remedy design studies will also be required to determine if soil
washing is a viable treatment alternative for a site. The remedy
selection evaluation should provide an indication that reduc-
tions in contaminant concentrations or in the volume of con-
taminated soil will meet site-specific cleanup goals. It will also
produce the design information required for the next level of
testing. Remedy design studies may be needed to optimize
process design.
TECHNOLOGY DESCRIPTION AND
PRELIMINARY SCREENING
Technology Description
Soil washing is a physical/chemical separation technology
in which excavated soil is pretreated to remove large objects
and soil clods and then washed with fluids to remove contami-
nants. To be effective, soil washing must either transfer the
contaminants to the wash fluids or concentrate the contami-
nants in a fraction of the original soil volume, using size separa-
tion techniques. In either case, soil washing must be used in
conjunction with other treatment technologies. Either the
washing fluid or the fraction of soil containing most of the
contaminant, or both, must be treated.
At the present time, soil washing is used extensively in
Europe and has had limited use in the United States. During
1986-1989, the technology was one of the selected source
control remedies at eight Superfund sites.
riS Printed on Recycled Paper
-------
The determination of the need for and the appropriate
level of treatability studies required is dependent on the litera-
ture information available on the technology, expert technical
judgment, and site-specific factors. Several reports and elec-
tronic data bases exist that should be consulted to assist in
planning and conducting treatability studies as well as help
prescreen soil washing for use at a specific site. Site-specific
technical assistance is provided to Regional Project Managers
(RPMs) and On-Scene Coordinators (OSCs) by the Technical
Support Project (TSP).
Prescreening Characteristics
Prescreening activities for the soil washing treatability test-
ing include interpreting any available site-related field measure-
ment data. The purpose of prescreening is to gain enough
information to eliminate from further treatability testing those
treatment technologies which have little chance of achieving
the cleanup goals.
The three most important soil parameters to be evaluated
during prescreening and remedy screening tests are the grain
size distribution, clay content, and cation exchange capacity.
Soil washing performance is closely tied to these three factors.
Soils with relatively large percentages of sand and gravel (coarse
material >2 mm in particle size) respond better to soil washing
than soils with small percentages of sand and gravel. Larger
percentages of clay and silt (fine particles smaller than 0.25
mm) reduce soil washing contaminant removal efficiency. In
general, soil washing is most appropriate for soils that contain
at least 50 percent sand/gravel, i.e., coastal sandy soils and soils
with glacial deposits. Soils rich in clay and silt tend to be poor
candidates for soil washing. Cation exchange capacity mea-
sures the tendency of the soil to exchange weakly held cations
in the soil for cations in the wash solution, which will be more
strongly bound to the soil. Soils with relatively low CEC values
(less than 50 to 100 meq/kg) respond better to soil washing
than soils with higher CEC values. Early characterization of
these parameters and their variability throughout the site pro-
vides valuable information for the initial screening of soil wash-
ing as an alternative treatment technology.
Chemical and physical properties of the contaminant should
also be investigated. Solubility in water (or other washing
fluids) is one of the most important physical characteristics.
Reactivity with wash fluids may, in some cases, be another
important characteristic to consider. Other contaminant char-
acteristics such as volatility and density may be important for
the design of remedy screening studies and related residuals
treatment systems. Speciation is important in metal-contami-
nated sites. Specific metal compounds should be quantified
rather than total metal concentration for each metal present at
the site.
There is no steadfast rule that specifies when to proceed
with remedy screening and when to eliminate soil washing as a
treatment technology based on a preliminary screening analy-
sis. A literature search indicating that soil washing may not
work at a given site should not automatically eliminate soil
washing from consideration. On the other hand, previous
studies indicating that pure chemicals will be effectively treated
using soil washing must be viewed with caution. Chemical
interactions in complex mixtures frequently found at Superfund
sites or interactions between soil and contaminants can limit
the effectiveness of soil washing. An analysis of the existing
literature, coupled with the site characterization, will provide
the information required to make an "educated decision."
However, when in doubt, a remedy screening study is recom-
mended.
Technology Limitations
Many factors affect the feasibility of soil washing. These
factors should be addressed prior to the selection of soil wash-
ing, and prior to the investment of time and funds in further
testing. A detailed discussion of these factors is beyond the
scope of this document
THE USE OF TREATABILITY STUDIES IN
REMEDY SELECTION
Treatability studies should be performed in a systematic
fashion to ensure that the data generated can support the
remedy evaluation and implementation process. A well-designed
treatability study can significantly reduce the overall uncer-
tainty associated with the decision but cannot guarantee that
the chosen alternative will be completely successful. Care must
be exercised to ensure that the treatability study is representa-
tive of the treatment as it will be employed (e.g., the sample is
representative of the contaminated soil to be treated) to mini-
mize the uncertainty in the decision. The method presented
below provides a resource-effective means for evaluating one or
more technologies.
There are three levels or tiers of treatability studies: remedy
screening remedy selection and remedy design. Some or all of
the levels may be needed on a case-by-case basis. The need for,
and the level of, treatability testing required are management
decisions in which the time and cost necessary to perform the
testing are balanced against the risks inherent in the decision
(e.g., selection of an inappropriate treatment alternative). Fig-
ure 1 shows the relationship of three levels of treatability study
to each other and to the RI/FS process.
Remedy Screening
Remedy screening is the first level of testing. It is used to
establish the ability of a technology to treat a waste. These
studies are generally low cost (e.g., 110,000 to $50,000) and
usually require hours to days to complete. The lowest level of
quality control is required for remedy screening studies. They
yield data enabling a qualitative assessment of a technology's
potential to meet performance goals. Remedy screening tests
can identify operating standards for investigation during rem-
edy selection or remedy design testing. They generate little, if
any, design or cost data, and should never be used as the sole
basis for selection of a remedy.
-------
Remedial Investigation/
Feasibility Study (RI/FS)
Identification
of Alternatives
Record of
Decision
(ROD)
Remedy
Selection
Remedial Design/
Remedial Action -
(RD/RA)
Scoping
- the -
RI/FS
Literature
Screening
and
Treatability
Study Scoping
Site
Characterization
and Technology
Screening
REMEDY
SCREENING
to Determine
Technology Feasibility
Evaluation
of Alternatives
REMEDY SELECTION
to Develop Performance
and Cost Data
Implementation
of Remedy
REMEDY DESIGN
to Develop Scale-Up, Design,
and Detailed Cost Data
Figure 1. The Role of Ttreotablllty Studies in the RI/FS and RD/RA Process.
Remedy screening soil washing treatability studies are fre-
quently skipped. Often, there is enough information about the
physical and chemical characteristics of the soil and contami-
nant to allow an expert to evaluate the potential success of soil
washing at a site. When performed, remedy screening tests are
jar tests. However, remedy selection tests are normally the first
level of treatability study executed.
Remedy Selection
Remedy selection testing is the second level of testing.
Remedy selection tests identify the technology's performance
for a site. These studies have a moderate cost (e.g., $20,000 to
5100,000) and require several weeks to complete. Remedy
selection tests yield data that verify that the technology can
meet expected cleanup goals, provide information in support
of the detailed analysts of alternatives (i.e., seven of the nine
evaluation criteria), and give indications of optimal operating
conditions.
The remedy selection tier of soil washing testing generally
consists of laboratory tests which provide sufficient experimen-
tal controls such that a semi-quantitative mass balance can be
achieved. Toxicity testing of the cleaned soil is typically em-
ployed in the remedy selection tier of treatability testing. The
key question to be answered during remedy selection testing is
how much of the soil will this process treat by either particle size
separation or solubilization to meet the cleanup goal. The
exact removal efficiency needed to meet the specified goal for
the remedy selection test is site-specific. In some cases, pilot-
scale testing may be appropriate to support the remedy evalua-
tion of innovative technologies. Typically, a remedy design
study would follow a successful remedy selection study.
Remedy Design
Remedy design testing is the third level of testing. It
provides quantitative performance, cost, and design informa-
tion for remediating an operable unit. This testing also pro-
duces remaining data required to optimize performance. These
studies are of moderate to high cost (e.g., $100,000 to
$500,000) and require several months to complete. For com-
plex sites (e.g., sites with different types or concentrations of
contaminants in different areas or with different soil types in
different areas), longer testing periods may be required, and
costs will be higher. Remedy design tests yield data that verify
performance to a higher degree than the remedy selection and
provide detailed design information. They are performed dur-
ing the remedy implementation phase of a site cleanup.
Remedy design tests usually consist of bringing a mobile
treatment unit onto the site, or constructing a small-scale unit
for nonmobile technologies. Permit exclusions may be avail-
able for offsite treatability studies under certain conditions. The
goal of this tier t>f testing is to confirm the cleanup levels and
treatment times specified in the Work Plan. This is best achieved
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by operating a field unit under conditions similar to those
expected in the full-scale remediation project
Data obtained from the remedy design tests are used to:
• Design the full-scale unit
• Confirm the feasibility of soil washing based on target
cleanup goals
• Refine cleanup time estimates
• Refine cost predictions.
Given the lack of full-scale experience with innovative
technologies, remedy design testing will generally be necessary
in support of remedy implementation.
REMEDY SELECTION TREATABILITY
STUDY WORK PLAN
Carefully planned treatability studies are necessary to en-
sure that the data generated are useful for evaluating the
validity or performance of a technology. The Work Plan, which
is prepared by the contractor when the Work Assignment is in
place, sets forth the contractor's proposed technical approach
for completing the tasks outlined in the Work Assignment It
also assigns responsibilities and establishes the project schedule
and costs. The Work Plan must be approved by the RPM before
initiating subsequent tasks. A suggested organization of the
Work Plan is provided in the "Guide for Conducting Treatability
Studies Under CERCLA Soil Washing."
Test Goals
Setting goals for the treatability study is critical to the
ultimate usefulness of the data generated. Goals must be
defined before the treatability study is performed. Each tier of
treatability study needs performance goals appropriate to that
tier.
Remedy screening tests are not always performed for soil
washing processes. If remedy screening tests are performed, an
example of the goal for those tests would be to show that the
wash fluid will solubilize or remove a sufficient percentage (e.g.,
50 percent) of the contaminants to warrant further treatability
studies. Another goal might be to show that contaminant
concentrations can be reduced in the >2 mm soil fraction by at
least 50 percent, as compared to the original soil concentra-
tions, using particle size separation techniques. These goals are
only examples. The remedy screening treatability study goals
must be determined on a site-specific basis.
Achieving the goals during this tier should merely indicate
that soil washing has at least a limited chance of success and
that further studies will be useful. Frequently, such information
is available based on the type of soil and contaminant present
at the site. Based on such information, experts in soil washing
technology can often assess the potential applicability of soil
washing without performing remedy screening.
The main objectives of the remedy selection tier of testing
are to:
• Measure the percentage of the contaminant that can
be removed from the soil through solubilization or
from the >2 mm soil fraction by particle size separa-
tion.
• Produce the design information required for the next
level of testing, should the remedy selection evalua-
tion indicate remedy design studies are warranted.
• The actual goal for removal efficiency must be based
on site- and process-specific characteristics. The speci-
fied removal efficiency must meet site cleanup goals,
which are based on a site risk assessment or on the
applicable or relevant and appropriate requirements
(ARARs).
Experimental Design
A jar test is the type of remedy screening test that can be
rapidly performed in an onsite laboratory to evaluate the poten-
tial performance of soil washing as an alternative technology.
Such studies should be designated to maximize the chances of
success at the remedy screening level. The object of this guid-
ance document is not to specify a particular remedy screening
method but rather to highlight those critical parameters which
should be evaluated during the laboratory test.
Contaminant characteristics to examine during remedy
screening include solubility, miscibility, and dispersibility. Prop-
erties of organic contaminants are generally easier to evaluate
than those of inorganic contaminants. Inorganics, such as
heavy metals, can exist in many compounds (e.g., oxides,
hydroxides, nitrates, phosphates, chlorides, sulfates, and other
more complex mineralized forms), which can greatly alter their
solubilities. Metal analyses typically provide only total metal
concentrations. More detailed analyses to determine chemical
speciation may be warranted.
The liquid used in the jar test is typically water, or water
with additives which might enhance the effectiveness of the soil
washing process. To save time and money, chemical analyses
should not be performed on the samples until there is visual
evidence that physical separation has taken place in the jar
tests, jar tests can yield three separate fractions from the
original soil sample. These include a floating layer, a wastewa-
ter with dispersed solids, and a solid fraction. Chemical analysis
can be performed on each fraction.
When performing the jar test, observe if any floating mate-
rials can be skimmed off the top. Observe whether an immis-
cible, oily layer forms, either at the top or the bottom, indicat-
ing release of an insoluble organic material. Observe and time
the solids settling rate and depth. Sand and gravel settle first,
followed by the silt and clay. The rate and the relative volume
of the settling material will provide some indication of the
particle size distribution in the waste matrix and the potential
for soil washing as a treatment alternative. Further evidence
can be gained by analyzing the settled and filtered wash water
-------
for selected indicator contaminants of concern. If simple wash-
ing releases a large percentage of these contaminants into the
wash water, then soil washing can be viewed favorably and
more detailed laboratory and bench tests must be conducted.
Variations on the jar tests can include the addition of
surfactants, chelants, or other dispersant agents to the water;
sequential washing; heated water washing versus cold water;
acidic or basic wash water; and tests that include both a wash
and a rinse step. The rinse water and fine soil fraction (<2 mm
particle size) should be separated from the coarse soil fraction
(>2 mm particle size) using a #10 sieve. No attempt should be
made during jar tests to separate the soil into discrete size
fractions; this is done at the bench-scale tier of testing. Nor-
mally, only the coarse soil fraction should be analyzed for
contamination. In general, at least a 50 percent reduction in
total contaminant concentration in the >2 mm soil fraction is
considered adequate to proceed to the remedy selection tier.
The separation of approximately 50 percent of the total soil
volume as clean soil also indicates remedy selection studies may
be warranted.
To reduce analytical costs during the remedy screening
tier, a condensed list of known contaminants must be selected
as indicators of performance. The selection of indicator analytes
to track during jar testing should be based on the following
guidelines:
• Select one or two contaminants present in the soil
that are most toxic or most prevalent.
• Select indicator compounds to represent other chemi-
cal groups if they are present in the soil (i.e., volatile
and semivolatile organics, chlorinated and
nonchlorinated species, etc.)
• If polychlorinated biphenyls (PCBs) and dioxins are
known to be present, select PCBs as indicators in the
jar tests and analyze for them in the washed soil. It is
usually not cost-effective to analyze for dioxins and
other highly insoluble chemicals in the wash water
generated from jar tests. Check for them later in the
wash water from remedy selection tests.
Remedy selection tests require that electricity, water, and
additional equipment are available. The tests are run under
more controlled conditions than the jar tests. The response of
the soil sample to variable washing conditions is fully charac-
terized. More precision is used in weighing, mixing, and
particle size separation. There is an associated increase in QA/
QC costs. Treated soil particles are separated during the sieve
operations to determine contaminant partitioning with par-
ticle size. Chemical analyses are performed on the sieved soil
particles as well as on the spent wash waters. The impact of
process variables on washing effectiveness is quantified. This
series of tests is considerably more costly than jar tests, so only
samples showing promise in the remedy screening phase (jar
test) should be carried forward into the remedy selection tier.
If sufficient data are available in the prescreening step, the
remedy screening step may be skipped. Soil samples showing
promise in the prescreening step are carried forward to the
remedy selection tier.
A series of tests should be designed that will provide
information on washing and rinsing conditions best suited to
the soil matrix under study. The RREL data base should be
searched for information from previous studies. To establish
percent of contaminant removal, particle size separation, and
distribution of contaminants in the washed soil, the following
should first be studied: 1) wash time, 2) wash water-to-soil
ratio, and 3) rinse water-to-wash water ratio. Following those
studies, the effect of wash water additives on performance
should be evaluated.
Several factors must be considered in the design of soil
washing treatability studies. A remedy selection test design
should be geared to the type of system expected to be used in
the field. Soil-to-wash water ratios should be planned using the
results from the jar tests, if jar tests were performed. In general,
a ratio of 1 part of soil to 3 parts of wash water will be sufficient
to perform remedy selection tests. The soil and wash water
should be mixed on a shaker table for a minimum of 10
minutes and a maximum of 30 minutes. The soil-to-wash
water ratio and mix times presented here are rules of thumb to
be used if no other information is available.
Another factor to consider is the variability of the grain
size distribution. Cilsen Wet Sieve devices are recommended
for remedy selection studies. Ro-Tap or similar sieve systems
may also be used. Such devices will enhance the complete-
ness and reproducibility of grain size separation. However,
they are messy, expensive, and very noisy when in operation.
An alternate choice is to complete a series of four to six
replicate runs under exactly the same set of conditions to
obtain information on the variability of the grain size separa-
tion technique. Variability in the separation technique can be
evaluated by comparing sieve screen weights across runs and
soil contaminant data for the same fractions from each run.
By identifying the range of variability associated with re-
peated runs at the same conditions, estimates can be made of
the variability that is likely to be associated with other test
runs under slightly different conditions.
Normally, only the wash water and the soil particles cap-
tured by the sieve screen need to be analyzed for contaminants.
Experience has shown that little additional contaminant re-
moval is likely to be found in the rinse water. Rinsing is
important and must be included in the procedure since it
improves the efficiency of the grain size separation/sieving
process. Rinsing separates the fine from the coarse material.
This can result in a cleaner coarse fraction and more contami-
nant concentrated in the fine fraction. Contaminant concen-
tration in the rinse water may be determined periodically (e.g.,
10 percent of the samples) to evaluate the performance of the
wash solution. However, very little contamination is typically
dissolved in the rinse solution. Therefore, analyses of the rinse
solution may have limited value in verifying wash solution
performance.
Initially, only the coarse soil fraction and the wash water
should be analyzed for indicator contaminants. If the removal
of the indicator contaminants confirms that the technology has
the potential to meet cleanup standards at the site, additional
analyses should be performed. All three soil fractions and all
wash and rinse waters must be analyzed for all contaminants to
-------
perform a complete mass balance. The holding time of soil
fractions in the lab before extraction and analysis can be an
important consideration for some contaminants.
The decision on whether to perform remedy selection
testing on hot spots or composite soil samples is difficult and
must be made on a site-by-site basis. Hot spot areas should be
factored into the test plan if they represent a significant portion
of the waste site. However, it is more practical to test the
specific waste matrix that will be fed to the full-scale system
over the bulk of its operating life. If the character of the soil
changes radically (e.g., from clay to sand) over the depth of
contamination, then tests should be designed to separately
study system performance on each soil type.
Additives such as oil and grease dispersants and chelating
agents can aid in removing contaminants from some soils.
However, they can also cause processing problems downstream
from the washing step. Therefore, use of such additives should
be approached with caution. Use of one or a combination of
those additives is a site-by-site determination. Some soils do
not respond well to additives. Surfactants and chelating agents
may form suspensions and foams with soil particles during
washing. This can clog the sieves and lead to inefficient particle
size separation during screening. The result can be the recovery
of soil fractions with higher contamination than those cleaned
by water alone. Such results can make the data impossible to
understand. Additives can also complicate the rinse water
process that might follow the soil washing. Recent studies have
shown that counter-current washing-rinsing systems, incorpo-
rating the use of hot water for the initial wash step, offer the
best performance in terms of particle size separation, contami-
nant removal, and wastewater management (treatment, re-
cycling and discharge).
SAMPUNG AND ANALYSIS PLAN
The Sampling and Analysis Plan (SAP) consists of two
parts—the Field Sampling Plan (FSP) and the Quality Assurance
Project Plan (QAPjP). A SAP is required for all field activities
conducted during the RI/FS. The purpose of the SAP is to
ensure that samples obtained for characterization and testing
are representative and that the quality of the analytical data
generated is known. The SAP addresses field sampling, waste
characterization, and sampling and analysis of the treated wastes
and residuals from the testing apparatus or treatment unit. The
SAP is usually prepared after Work Plan approval.
Field Sampling Plan
The FSP component of the SAP describes the sampling
objectives; the type, location, and number of samples to be
collected; the sample numbering system; the necessary equip-
ment and procedures for collecting the samples; the sample
chain-of-custody procedures; and the required packaging, la-
beling, and shipping procedures.
Field samples are taken to provide baseline contaminant
concentrations and material for the treatability studies. The
sampling objectives must be consistent with the treatability test
objectives. Because the primary objective of remedy screening
studies is to provide a first-cut evaluation of the extent to which
specific chemicals are removed from the soil or concentrated in
a fraction of the soil by soil washing, the primary sampling
objectives should include, in general:
• Acquisition of samples representative of conditions
typical of the entire site or defined areas within the
site. Because this is a first-cut evaluation, elaborate
statistically designed field sampling plans may not be
required. Professional judgment regarding the sam-
pling locations should be exercised to select sampling
sites that are typical of the area (pit, lagoon, etc.) or
appear above the average concentration of contami-
nants in the area being considered for the treatability
test. This may be difficult because reliable site charac-
terization data may not be available early in the reme-
dial investigation.
• Acquisition of sufficient sample volumes necessary for
testing, analysis, and quality assurance and quality
control.
The sampling plan for remedy selection will be similar.
However, because a mass balance is required for this evalua-
tion, a statistically designed field sampling plan will be required.
Quality Assurance Project Plan
The Quality Assurance Project Plan should be consistent
with the overall objectives of the treatability study. At the
remedy screening level the QAPjP should not be overly detailed.
The purpose of the remedy selection treatability study is to
determine whether soil washing can meet cleanup goals and
provide information to support the detailed analysis of alterna-
tives (i.e., seven of the nine evaluation criteria). An example of
a criterion for this determination is removal of approximately
90 percent of contaminants. The exact removal efficiency
specified as the goal for the remedy selection test is site-specific.
The suggested QC approach will consist of:
• Triplicate samples of both reactor and controls
• The analysis of surrogate spike compounds in each
sample
• The extraction and analysis of a method blank with
each set of samples
• The analysis of a matrix spike in approximately 10
percent of the samples.
-------
The analysis of triplicate samples provides for the overall
precision measurements that are necessary to determine whether
the difference is significant at the chosen confidence level. The
analysis of the surrogate spike will determine if the analytical
method performance is consistent (relatively accurate). The
method blank will show 'rf laboratory contamination has had an
impact on the analytical results.
Selection of appropriate surrogate compounds will de-
pend on the target compounds identified in the soil and the
analytical methods selected for the analysis.
TREATABILITY DATA INTERPRETATION
The information and results gathered from the remedy
screening are used to determine if soil washing is a viable
treatment option and to determine if additional remedy selec-
tion and remedy design studies are warranted. A reduction of
approximately SO percent of the soil contaminants during the
test indicates additional treatability studies are warranted. Con-
taminant concentrations can also be determined for wash wa-
ter and fine soil fractions. These additional analyses add to the
cost of the treatability test and may not be needed. Before and
after concentrations can normally be based on duplicate samples
at each period. The mean values are compared to assess the
success of the study, tf the remedy screening indicates that soil
washing is a potential cleanup option then remedy selection
studies should be performed.
In remedy selection treatability studies, soil contaminant
concentrations before soil washing and contaminant concen-
l trations in the coarse fraction after soil washing are typically
measured in triplicate. A reduction of approximately 90 percent
in the mean concentration indicates soil washing is potentially
useful in site remediation. A number of other factors must be
evaluated before deciding to proceed to remedy design studies.
The final concentration of contaminants in the recovered
(clean) soil fraction, in the fine soil fraction and wastewater
treatment sludge, and in the wash water are important to
evaluating the feasibility of soil washlhg. The selection of
technologies to treat the fine soil and wash water wastestreams
depends upon the types and concentrations of contaminants
present. The amount of volume reduction achieved is also
important to the selection of soil washing as a potential reme-
diation technology.
TECHNICAL ASSISTANCE
Literature information and consultation with experts are
critical factors in determining the need for and ensuring the
usefulness of treatability studies. A reference list of sources on
treatability studies is provided in the "Guide for Conducting
Treatability Studies Under CERCLA" (EPA/540/2-89/058).
It is recommended that a Technical Advisory Committee
(TAQ be used. This committee includes experts on the tech-
nology who provide technical support from the scoping phase
of the treatability study through data evaluation. Members of
the TAC may include representatives from EPA (Region and/or
ORD), other Federal Agencies, States, and consulting firms.
OSWER/ORD operate the Technical Support Project (TSP)
which provides assistance in the planning, performance, and/or
review of treatability studies. For further information on treat-
ability study support or the TSP, please contact:
Ground water Fate and Transport Technical
Support Center
Robert S. Kerr Environmental Research Laboratory
(RSKERL), Ada, OK
Contact: Don Draper
FTS 743-2200 or (405) 332-8800
Engineering Technical Support Center
Risk Reduction Engineering Laboratory (RREL),
Cincinnati, OH
Contact: Ben Blaney
FTS 684-7406 or (513) 569-7406
FOR FURTHER INFORMATION
In addition to the contacts identified above, the appropri-
ate Regional Coordinator for each Region located in the Haz-
ardous Site Control Division/Office of Emergency and Remedial
Response or the CERCLA Enforcement Division/Office of Waste
Programs Enforcement should be contacted for additional in-
formation or assistance.
ACKNOWLEDGEMENTS
The fact sheet and the corresponding guidance document
were prepared for the U.S. Environmental Protection Agency,
Office of Research and Development (ORD), Risk Reduction
Engineering Laboratory (RREL), Cincinnati, Ohio, by Science
Applications International Corporation (SAIC) under Contract
No. 68-C8-0061. Mr. Mike Borst and Ms. Malvina Wilkens
served as the EPA Technical Project Monitors. Mr. Jim Rawe
and Dr. Thomas Fogg served as SAIC's Work Assignment
Managers. The project team included Kathleen Hurley, Curtis
Schmidt, Cynthia Eghbalnia, and Yueh Chuang of SAIC; Pat
Esposito of Bruck, Hartman & Esposito, Inc.; lames Nash of
Chapman, Inc. Mr. Clyde Dial served as SAIC's Senior Reviewer.
Many other Agency and independent reviewers have con-
tributed their time and comments by participating in the expert
review meetings and/or peer reviewing the guidance document.
-------
United States Center for Environmental Research BULK RATE
Environmental Protection Information POSTAGE & FEES PAID
Agency Cincinnati, OH 45268 EPA PERMIT NO. G-3S
Official Business
Penalty for Private Use $300
EPA/540/2-91/020B
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United States
Environmental Protection
Agency
EPA/540/SR-93/508
March 1994
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
Technology Demonstration
Summary
EPA RREL's Mobile Volume
Reduction Unit
A Superfund Innovative Technology
Evaluation (SITE) demonstration of the
mobile Volume Reduction Unit (VRU)
was conducted in November 1992 at
the Escambia Wood Treating Company
Superfund Site in Pensacola, FL The
VRU is a soil washing technology that
may be used to rid soils of organic
contaminants. The VRU is designed to
remove contaminants by suspending
them in a wash solution and by reduc-
ing the volume of contaminated mate-
rial through particle size separation.
For the SITE demonstration, the VRU
was used to treat soil contaminated
with wood-treating agents, pentachlo-
rophenol (POP) and creosote-fraction
polynuclear aromatic hydrocarbons
(PAHs). Demonstration test results indi-
cate that the VRU soil washing system
successfully separated the contami-
nated soil into two unique streams:
washed soil and fines slurry. The
washed soil was safely returned to the
site following treatment. The fines
slurry, which carried the majority of
the pollutants from the feed soil, un-
derwent additional treatment to sepa-
rate the fines from the water.
An economic analysis was conducted
to estimate costs for a commercial
treatment system using the VRU tech-
nology. This analysis was based on
the pilot-scale results from the SITE
demonstration. The economic analysis
was developed for a commercial unit
projected to be capable of treating ap-
proximately 10 tons per hour (tph) of
contaminated soil. The cost to
remediate 20,000 tons of contaminated
soil using this commercial unit is esti-
mated to be $130 per ton if the system
is online 90% of the time. Treatment
costs appear to be competitive with
other available technologies.
This Summary was developed by EPA's
Risk Reduction Engineering Laboratory,
Cincinnati, OH, to announce key findings
of the SITE program demonstration that is
fully documented in two separate reports.
(see ordering information on back).
Introduction
In response to the Superfund Amend-
ments and Reauthorization Act of 1986,
EPA's Office of Research and Develop-
ment and Office of Solid Waste and Emer-
gency Response have established the
SITE Program to accelerate the develop-
ment, demonstration, and use of new or
innovative technologies as alternatives to
current treatment systems for hazardous
wastes.
-------
The major objective of the SITE Pro-
gram is to develop reliable performance
and cost information for innovative tech-
nologies. One such technology is EPA's
mobile VRU, which was demonstrated over
a 2-wk period beginning November 5,
1992, and ending November 13, 1992.
The demonstration was conducted at the
Escambia Wood Treating Company
Superfund Site in Pensacola, FL.
The VRU is a soil washing technology
designed to rid soils of organic contami-
nants through particle size separation and
solubilization. The concept of reducing soil
contamination through the use of particle
size separation is based on the finding
that most organic and inorganic contami-
nants tend to bind to fine clay and silt
particles primarily by physical processes.
Critical and noncritical project objectives
were established to evaluate the effec-
tiveness of the process. Critical param-
eters provided data to support project ob-
jectives. Noncritical measurements
provided additional information on the
technology's applicability to other
Superfund sites and allowed observation
and documentation of any process perfor-
mance anomalies. The following were the
critical project objectives:
• Determine the system's ability to re-
move 90% of the PCP and creosote-
fraction PAH contaminants from the
feed soil.
• Determine the system's ability to re-
turn 80% of the solids in feed soil as
washed soil.
• Perform mass balances on the fol-
lowing:
- Total material: This is the ratio of
the total mass of all output streams
from the soil washing segment of
the VRU to the total mass of all
corresponding input streams.
- Total dry solids: This is the ratio of
the total mass of dry solids in all
output streams from the soil wash-
ing segment of the VRU to the total
mass of dry solids in all correspond-
ing input streams.
- PCP: This is the ratio of the total
mass of PCP in all output streams
from the soil washing segment of
the VRU to the total mass of PCP
in corresponding input streams.
- PAHs: This is the ratio of the total
mass of PAHs in all output streams
from the soil washing segment of
the VRU to the total mass of PAHs
in all corresponding input streams.
• Verify VRU operating conditions: This
includes measuring the pH of the
wash water, the ratio of surfactant to
wash water, and the temperature.
The noncritical project objectives of this
demonstration were to determine the
technology's general applicability and to
document process performance. The non-
critical project objectives were as follows:
• Determine removal efficiencies of the
unit operations in the water purifica-
tion system.
• Develop operating costs.
Process and Facility
Description
The demonstration of the VRU was per-
formed at the Escambia Wood Treating
Company Superfund Site located in
Pensacola, FL. The 26-acre facility, now
closed, used PCP and creosote to treat
wood products from 1943 to 1982. A typi-
cal VRU setup is shown in Figure 1. For
this demonstration, the VRU was com-
posed of two segments: soil washing and
water treatment. The soil washing seg-
ment produces fines slurry and washed
soil streams. The water treatment seg-
ment treats the fines slurry by separating
the fines and removing pollutants from the
wash water through a series of steps in-
cluding sedimentation, flocculation, filtra-
tion, and carbon adsorption.
In this setup, the soil is fed to the
miniwasher at a controlled rate of approxi-
mately 100 Ib/h by the screw conveyor.
Filtered wash water is added to the soil in
the miniwasher and also sprayed onto an
internal slotted trommel screen [with a 10-
mesh (2-mm) slot opening] in the
miniwasher. Two vibrascreens continu-
ously segregate soil into various size frac-
tions. For the demonstration, 10-mesh (2-
mm) and 100-mesh (0.15-mm) screens
were used.
Miniwasher overflow (the stream exiting
the top of the washer), which contains the
coarse soil fraction, falls onto the first 10-
mesh (2-mm) vibrascreen. Solids that over-
flow the first vibrascreen [less than
1/4 in, greater than 10 mesh (0.15 mm)]
flow by gravity down to a recovery drum.
The underflow (the stream exiting the bot-
tom) is pumped at a controlled rate to the
second 100-mesh (0.15-mm) vibrascreen,
where it is joined by the miniwasher
underflow.
The overflow from the second
vibrascreen [less than 10 mesh (2 mm),
greater than 100 mesh (0.15 mm)] is grav-
ity fed to the recovery drum containing the
overflow from the first vibrascreen. The
second vibrascreen underflow (a fine?
slurry) drains into a tank with a mixer.
Slurry from the 100-mesh (0.15-mm)
screen (fines slurry) tank, which contains
particles less than 100 mesh (0.15 mm) in
size, is pumped to the Corrugated Plate
Interceptor (CPI). Materials lighter than
water (floatables such as oil) flow over an
internal weir, collect in a compartment
within the CPI, and drain by gravity to a
drum for disposal. Solids settled in the
CPI [particles less than 100 mesh (0.15
mm)] are discharged by the bottom auger
to a recovery drum.
An aqueous slurry, which contains fines
less than about 400 mesh (0.038 mm),
overflows the CPI and gravity feeds into a
tank with a mixer. The slurry is then
pumped to a static mixer located upstream
of the floe clarifier's mix tank. Flocculating
chemicals, such as liquid alum and aque-
ous polyelectrolyte solutions, are metered
into the static mixer tank to neutralize the
electrostatic charges on colloidal particles
(clay/humus) and promote coagulation.
The slurry is then discharged into the floe
chamber, which has a variable- speed agi-
tator to stimulate floe growth. The floe
slurry overflows into the clarifier (another
CPI). Bottom solids are augured to a drum
for disposal.
Clarified water is polished with the ob-
jective of reducing suspended solids and
organics to low levels that permit recy-
cling of spent wash water. Water is
pumped from the floe settler overflow tank
at a controlled rate through cartridge-type
polishing filters operating in parallel to re-
move soil fines greater than 4 x 10"4 in.
Water leaving the cartridge filter flows
through activated carbon drums for re-
moval of hydrocarbons. The carbon drums
may be operated either in series or paral-
lel. Hydrocarbon breakthrough is moni-
tored by sampling; drums are replaced
when breakthrough is detected.
Feed Soil Characteristics
PAH- and PCP-contaminated soil from
the former Escambia Wood Treating Com-
pany site was excavated and then treated
by the VRU. Contaminant levels in the
excavated soil from the Escambia Wood
Treating Company site ranged from the
low parts per million (ppm) to percent lev-
els. For the SITE demonstration, the ex-
cavated soil was homogenized and manu-
ally processed through a 1/4-in. screen
before it was fed to the VRU. Contami-
nant concentrations in the feed soil after
homogenization and screening are pre-
sented in Table 1. j
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Table 1. Contaminant Concentrations in the
Feed Soil (pom, dry weight oasis)
Average Range
PAHs
PCP
920
130
480 to 1,500
43 to 200
Sampling and Monitoring
During the demonstration, the VRU op-
erated at a feed rate of approximately 100
Ib/h with wash water-to-feed (W/F) ratio of
6 to 1. The physical condition of the wash
water was modified during the demonstra-
tion with combinations of surfactant, caus-
tic, and temperature as follows:
• Condition 1: no surfactant, no pH ad-
justment, no temperature adjustment
• Condition 2: surfactant addition, no
pH adjustment, no temperature ad-
justment
• Condition 3: surfactant addition, pH
adjustment, temperature adjustment
The VRU operated under Conditions 1
and 2 three consecutive times; each run
was 4 hr in duration. On the 7th day of
testing, the generator that supplied the
power to the test site failed, and conse-
quently, testing was terminated and the
data were not used. In order to remain on
schedule and collect an equivalent amount
of data for the third set of conditions, two
6-hr runs were conducted under Condi-
tion 3. Sample collection and flow mea-
surements began when each run reached
steady state. The unit ran for approxi-
mately 1 hr before reaching steady state
conditions. The sampling locations, which
are designated S1, S2, etc., are described
in Table 2.
Results and Discussion
PCP removal efficiency was calculated
for Conditions 1, 2, and 3. Under Condi-
tion 1, the average PCP removal efficiency
was 81%, which is below the project ob-
jective of achieving at least 90%. Under
Condition 2, which employed surfactant
addition only, the average removal effi-
ciency was 93%. This performance ex-
ceeds the project objective and reflects
the surfactant's ability to pull hydrophobic
PCP into the wash water. Under Condi-
tion 3, which employed surfactant addition
and pH and temperature adjustment, 97%
of the PCP was removed. These data
illustrate that the PCP removal efficiency
Water Heater
Makeup Water Tank
Slowdown Tank
Carbon Drums
Emissions Control
.Screw Conveyor
Trommel Screen
Mini-Washer
Screen Soil Fractions
Electric Generator Floc-Clarifier
Filter Package
Figure 1. Typical VRU operational setup.
-------
Table 2. Sampling Locations for VRU Demonstration Test
Process Stream
(Sample Location)
Matrix
Feed Soil (S1)
Feed Water (S2)
Surfactant (S3)
Caustic (S4)
Washed Soil (S5)
Fines Slurry (S6)
Water Roatables (S7)
CPI Fines (S8)
Flocculant Fines (S9)
Clarified Water (S10)
Post-Filtration Water (S11)
Post-Carbon Adsorption Water (S12)
Solid
Liquid
Liquid
Liquid
Solid
Slurry
Liquid
Slurry
Slurry
Liquid
Liquid
Liquid
is clearly enhanced by surfactant addition
and pH and temperature adjustment.
. PAH removal efficiency was calculated
for Conditions 1, 2, and 3. Under Condi-
tion 1, the average PAH removal efficiency
was 76%, which is again below the project
objective of achieving at least 90%. Under
Condition 2, the average removal efficiency
was 86%. This performance is also below
the project objective; however, the large
rise in removal efficiency reflects the
surfactant's ability to transfer PAHs into
the wash water. The average PAH re-
moval efficiency for Condition 3 increased
to 96%. These data illustrate that the PAH
removal efficiency is clearly enhanced by
surfactant addition and pH and tempera-
ture adjustment.
As soil travels through the VRU, the
sand and gravel fraction of the soil are
separated from the contaminated fines
(i.e., fines particles). The relatively non-
hazardous sand and gravel fraction exits
the system as washed soil. By comparing
the mass of dry solids in the feed soil with
the mass of dry solids in the washed soil,
solids recoveries of 96%, 95%, and 81%
were calculated for soils treated under
Conditions 1, 2, and 3. These recoveries
exceed the project objective that at least
80% of the solids present in the feed soil
would be returned to the site as washed
soil.
Washed soil recovery was also deter-
mined on a normalized basis, which com-
pares the mass of dry solids in washed
soil to the combined mass of dry solids in
washed soil and fines slurry. Normalized
data minimize the effect that potential bi-
ases in the total solids balance could have
on this evaluation. Average, washed soil
recoveries on a normalized basis of 90%,
88%, and 86% were determined for Con-
ditions 1, 2, and 3, respectively. These
recoveries exceed the project objectives
that at least 80% of the solids present in
the feed soil would be returned to the site
as washed soil.
Mass balances are obtained by com-
paring the mass entering a system to the
mass exiting the system. The mass bal-
ance closures calculated for the VRU dem-
onstration are summarized in Table 3.
For the total material balance, the re-
covery is the percentage of the material
entering the system as feed soil and wash
water that was recovered from the system
as washed soil and fines slurry. The project
objective for the total material balances
was that closures would be between 90%
and 110%. A review of balance closures
reveals that acceptable performance cri-
teria were met for Conditions 1 (104%)
and 3 (98%) but not Condition 2 (113%).
During Condition 2, it was noted that the
mass flow rate measurement of the fines
slurry may have been affected by sam-
pling procedures employed during the
demonstration. This resulted in inflated
mass flow rates. The procedure was modi-
fied and the percent closures dropped to
the acceptable range. Dry solids recover-
ies during the VRU demonstration were
107%, 109% and 94% for Conditions 1, 2,
and 3, respectively, which meet project
objectives of recoveries between 85% and
115%.
Under Condition 1, the average mass
balance closures for PCP and PAHs were
101% and 87%, respectively. The aver'
age PCP and PAH recoveries for Condi-
tions 2 and 3 were below 80% and there-
fore did not meet the project objectives.
Because low PCP and PAH closures were
experienced when surfactant was added
to the wash water, it seems probable that
the surfactant interfered with the PCP and
PAH analyses.
The VRU's effectiveness is based on its
ability to separate soil fines [less than 100
mesh (0.15 mm)] from the coarser gravel
and sand fraction of the soil [greater than
100 mesh (0.15 mm)]. Significant con-
taminant concentration reductions can be
realized by the VRU, provided the major-
ity of the contaminants present in the feed
soil concentrate in the fines. Table 4 indi-
cates the percentage of fines and coarse
sand and gravel fraction from the feed soil
recovered in the washed soil and fines
slurry. The data indicate the majority of
the small particles were partitioned to the
fines slurry.
Pollutants were removed from the fines
slurry stream by a water treatment se-
quence that included settling, flocculation,
filtration, and carbon adsorption. Follow-
ing treatment in the CPI, where the fines
were separated by gravity, the overflow
was pumped to a flocculation/clarification
system for additional fines partitioning. CPI
and floe tank underflow streams were col-
lected and were to be analyzed for PCP
and PAHs; however, problems with the
analysis produced data of limited useful-
ness. Clarified water from floe tank over-
flow was pumped through cartridge pol-
ishing filters operated in parallel to remove
soil fines greater than 4 x 10"4. Water
exiting these filters then passed through
activated carbon drums for hydrocarbon
removal. The clarified water was analyzed
for total organic carbon (TOC) and total
residue (TR), which is the sum of total
suspended solids (TSS) and total dissolved
solids (TDS). Table 5 lists the TOC levels
of the clarified water, water from the filters
and activated carbon, and feed water.
Table 6 lists the TR levels from the clari-
Table 3. Average Mass Balance Closures (%)
Total Material Dry Solids
PCP
PAHs
Condition 1
Condition 2
Condition 3
104
113
98
107
109
94
94
19
13
88
28
14
-------
Table 4. Distribution of Fines and Coarse Gravel and Sand (%, dry weight basis)
Condition
Washed Soil
Fines Slurry
Closure
1
31
75
106
Fines
2
41
83
124
Coarse Sand and
3
54
110
164
1
104
1
105
2
102
2
104
Gravel
3
82
2
84
fied water, water from the filters and acti-
vated carbon, and feed water.
TOC reduction was affected significantly
when surfactant was introduced into the
system during Conditions 2 and 3. The
efficiency was affected because surfac-
tant was adsorbed on the carbon along
with the contaminants. Instead of having
the carbon available to adsorb the con-
taminants, many of the adsorption sites
were occupied by the surfactant.
Unadsorbed contaminants exited the car-
bon drum, which caused an increase in
TOC. TOC efficiency could be improved
by removing the surfactant before it en-
ters the carbon canisters or by using an-
other organic removal technology. The TR
reduction from the filter unit was minimal,
indicating that a finer-sized filter is needed.
An economic analysis has been devel-
oped to estimate costs (not including prof-
its), for a commercial treatment system.
The analysis is based on the results of
Table 5. TOC Levels in Water Streams (ppm)
the SITE demonstration, which used the
pilot- scale EPA VRU, operating at ap-
proximately 100 Ib/h.
It is projected that the commercial unit
will operate at 10-tph. The cost to
remediate 20,000 tons of contaminated
soil using a 10-tph VRU is estimated at
$130 per ton if the system is online 90%
of the time. Treatment costs increase as
the percent online factor decreases. Pro-
jected unit costs for a smaller site (10,000
tons of contaminated soil) are $163 per
ton; projected unit costs for a larger site
(200,000 tons) are $101 per ton.
Conclusions and
Recommendations
The VRU soil washing system success-
fully separated the contaminated soil into
two unique streams: washed soil and fines
slurry. The washed soil was safely re-
turned to the site following treatment. The
fines slurry, which carried the majority of
Feed Water Clarified Water Post-Filtration Post-Carbon
Water Adsorption Water
Condition 1
Condition 2
Condition 3
<1.0 11.5
<1.5 1,045
<1.02 825
11
1,075
697.5
<1.0
283
305
Table 6. TR Levels in Water Streams (ppm)
Feed Water Clarified Water Post-Filtration Post-Carbon
Water Adsorption Water
Condition 1
Condition 2
Condition 3
70
73
62
260
2,200
6,075
247.5
2,025
5,075
115
557.5
2,550
the pollutants from the feed soil, under-
went additional treatment to separate the
fines from the water.
The demonstration was divided into
three phases (Conditions 1, 2, and 3) that
evaluated the performance of the VRU
under varying wash water conditions. Un-
der Condition 1, using only ambient tem-
perature wash water with no additives,
average PCP and PAH removal efficien-
cies were 80% and 75%, respectively.
Under Condition 2, with the addition of
surfactant to ambient temperature wash
water, average PCP and PAH removal
efficiencies improved to 92% and 85%,
respectively. Under Condition 3, with the
addition of surfactant and caustic (for pH
adjustment) to the wash water at an el-
evated temperature, average PCP and
PAH removal efficiencies of 98% and 96%,
respectively, were achieved, exceeding the
project objective of 90% removal.
The results show the positive impact
that surfactant, pH adjustment, and in-
creased temperature have on PCP and
PAH removal efficiency. However, from
these data it is not possible to determine
whether pH adjustment, temperature, or
both these factors caused the increased
removal efficiency in Condition 3.
The ability of the VRU to produce
washed soil that meets the target cleanup
levels of 30 ppm PCP, 50 ppm carcino-
genic creosote, and 100 ppm total creo-
sote was also evaluated. The average
washed soil contaminant concentrations
for Condition 1 were 29 ppm PCP, 17
ppm carcinogenic creosote, and 240 ppm
total creosote. Under Condition 2, washed
soil contaminant concentrations improved
to 12 ppm PCP, 10 ppm carcinogenic
creosote, and 130 ppm total creosote.
Under Condition 3, washed soil contami-
nant concentrations further improved to 3
ppm PCP, 2.8 ppm carcinogenic creo-
sote, and 38 ppm total creosote.
Another primary objective of this SITE
demonstration was to determine whether
the VRU could recover 80% of the con-
taminated feed soil as clean washed soil.
Washed soils recoveries of 96%, 95%,
and 81% were calculated for Conditions
1, 2, and 3, respectively.
Washed soil recovery was also deter-
mined on a normalized basis that com-
pared the mass of dry solids in washed
soil to the combined mass of dry solids in
washed soil and fines slurry. Average
washed soil recoveries on a normalized
basis of 89%, 88%, and 86% were deter-
mined for Conditions 1, 2, and 3. This
indicates steady performance of the VRU
in treating a uniform feed soil. The system
consistently segregated the feed solids
-------
into washed soil and fines slurry, appear-
ing to be unaffected by fluctuations in
feed rate, W/F ratio, wash water addi-
tives, or other operating parameters.
Mass balances were calculated for total
materials, total dry solids, total POP, and
total PAHs for each condition. Closure
rates between 90% and 110% were
achieved for Conditions 1 and 3 for total
mass. Sampling procedures contributed
to a less than acceptable total materials
closure rate of 113% for Condition 2. Clo-
sure rates between 85% and 115% were
achieved for Conditions 1, 2, and 3 for
total dry solids. Mass balances for PCP
and PAHs achieved closure rates of be-
tween 85% and 175% for Condition 1
only. Mass balances for Conditions 2 and
3 were considered invalid and attributed
to surfactant addition that adversely af-
fected the analyses.
The VRU is designed to return feed soil
that is greater than 100 mesh (0.15 mm)
in size as washed soil. The data from the
demonstration indicate this soil is an ideal
candidate for treatment by the VRU. Ex-
cellent results for partitioning the greater
than 100- mesh (0.15-mm) particles
(coarse sand and gravel) to the washed
soil were achieved. Only 1% to 2% of
these particles was detected in the fines
slurry. A majority of less than 100-mesh
(0.15-mm) particles (fines) were isolated
in the fines slurry stream; however, the
partitioning was not as complete.
PCP and PAH solid fraction data con-
firm that material from the CPI and floe/
clarifier was highly contaminated. A more
complete partitioning of the less than 100-
mesh (0.15-mm) particles to the fines slurry
may lead to decreased contaminant lev-
els in washed soil and to increased re-
moval efficiency. An additional series of
unit operations, such as a trommel washer
and dispersing agent (e.g., sodium
hexametaphosphate) employed after the
vibrascreens, may help reduce the level
of fines in washed soil. The VRU was
designed with the ability to recycle water
treatment subsystem effluent to the
miniwasher; however, water quality crite-
ria for recycling have not been defined.
Although the developer claimed that the
effluent after water treatment would be of
sufficient quality to permit recycling into
the water tank for reuse as wash water,
this claim was not evaluated during the
demonstration. Prior to the demonstration,
the developer chose to operate the VRU
without recycling. The developer indicated
that the CPI/floc tank did not settle out as
much as expected, allowing more solids
and TOC to pass through the filters and
carbon. Based on the data presented in
Tables 5 and 6, the treated water pro-
duced during Condition 1 is considered
potentially suitable for recycling. The
treated water produced during Conditions
2 and 3 contained significantly higher lev-
els of TOC and TR and would likely re-
quire further treatment before it could be
recycled. If the treated water cannot be
reused as wash water, then it must be
disposed of. Disposal options may include
discharge to a local publicly-owned treat-
ment works (POTW). Discharge to a
POTW will typically be regulated accord-
ing to the industrial wastewater pretreat-
ment standards of the POTW. These stan-
dards are specified by EPA for certain
industries. Depending on the site, the
treated wash water may fall into one spe-
cific industrial category. If it does not, the
pretreatment standards for the wash wa-
ter will be determined by the POTW and
will depend on site-specific parameters
such as flow rate of the wash water, con-
taminants present, design of the POTW,
and receiving stream water quality stan-
dards. The developer indicated that solids
did not settle out in the CPI and floe/
clarifier as much as expected, allowing
more solids and organics to pass through
the filters and carbon. Excessive solids
may adversely affect the process by plug-
ging water lines. The commercial-scale
VRU proposed by EPA appears to be
suited to the remediation of soils and other
solid wastes contaminated with organic
compounds. Treatment costs appear to
be competitive with other available tech-
nologies. The cost to remediate 20,000
tons of contaminated soil using a 10-tph
VRU is estimated at $130 per ton if the
system is on-line 90% of the time. Treat-
ment costs increase as the percent on-
line factor decreases. Projected unit costs
for a smaller site (10,000 tons of contami-
nated soil) are $163 per ton; projected
unit costs for a larger site (200,000 tons)
are $101 per ton.
fcU-S. GOVUNMENT PUNTING OfTKXi MM
-------
The EPA Project Manager, Ten Richardson, is with the Risk Reduction
Engineering Laboratory, Cincinnati, OH 45268 (see below)
The complete report, entitled "Technology Evaluation Report: SITE Program
Demonstration EPA RREL Mobile Reduction Unit"
(Order No. PB94-136264; Cost: $27.00, subject to change) will be available
only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
Telephone: 703-487-4650
A related report, entitled "Applications Analysis Report EPA RREL Mobile
Volume Reduction Unit" (EPA/540/AR-93/508) is available as long as
supplies last from:
ORD Publications
26 W. Martin Luther King Drive
Cincinnati, OH 45268
Telephone: (513) 569-7562
The EPA Project Manager can be contacted at:
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/540/SR-93/5
®M 1B 1334
-------
Washinoton, DC 20460
EsB'a:SK%*w>K;r'" *»,,ff>'»«»v .PT^A™ ^ss-1 mm "-•*m'yi
ngmeenng Bulletin
^^'*'*' "°>* 'J*^' "c *'' ' '" - *'** '" * .'
«•*>*•*• ••~^ •,M,-^w~v.ia
Extraction
Purpose
Section 121(b) of the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA) man-
dates the Environmental Protection Agency (EPA) to select
remedies that "utilize permanent solutions and alternative
treatment technologies or resource recovery technologies
to the maximum extent practicable" and to prefer remedial
actions in which treatment "permanently and significantly
reduces the volume, toxicity, or mobility of hazardous
substances, pollutants, and contaminants as a principal
element." The Engineering Bulletins are a series of docu-
ments that summarize the latest information available on
selected treatment and site remediation technologies and
related issues. They provide summaries of and references
for the latest information to help remedial project manag-
ers, on-scene coordinators, contractors, and other site
cleanup managers understand the type of data and site
characteristics needed to evaluate a technology for poten-
tial applicability to their Superfund or other hazardous
waste site. Those documents that describe individual
treatment technologies focus on remedial investigation
scoping needs. This bulletin replaces the one on solvent
extraction issued in September 1990.
Abstract
Solvent extraction does not destroy hazardous con-
taminants, but is a means of separating those contaminants
from soils, sludges, and sediments, thereby reducing the
volume of the hazardous material that must be treated.
Generally it is used as one in a series of unit operations and
can reduce the overall cost for managing a particular site.
It is applicable to organic contaminants and is generally not
used for treating inorganic compounds and metals [1,
p.64].* The technology generally uses an organic chemical
as a solvent [2, p.30], and differs from soil washing, which
generally uses water or water with wash improving addi-
tives. Commercial-scale units are in operation. There is no
clear solvent extraction technology leader because of the
solvent employed, type of equipment used, or mode of
operation. The final determination of the lowest cost/best
performance alternative will be more site specific than
process dominated. Vendors should be contacted to
determine the availability of a unit for a particular site.
This bulletin provides information on the technology
applicability, the types of residuals produced, the latest
performance data, site requirements, the status of the
technology, and sources for further information.
Technology Applicability
Solvent extraction has been shown to be effective in
treating sediments, sludges, and soils containing prima-
rily organic contaminants such as polychlorinated biphe-
nyls (PCBs), volatile organic compounds (VOCs), haloge-
nated solvents, and petroleum wastes. The technology is
generally not used for extracting inorganics (i.e., acids,
bases, salts, heavy metals). Inorganics usually do not
have a detrimental effect on the extraction of the organic
components, and sometimes metals that pass through
the process experience a beneficial effect by changing to
a less toxic or teachable form. The process has been
shown to be applicable for the separation of the organic
contaminants in paint wastes, synthetic rubber process
wastes, coal tar wastes, drilling muds, wood treating
wastes, separation sludges, pesticide/insecticide wastes,
and petroleum refinery oily wastes [3].
Table 1 lists the codes for the specific Resources
Conservation and Recovery Act (RCRA) wastes that have
been treated by the technology [3][4, p. 11]. The effec-
tiveness of solvent extraction on general contaminant
groups for various matrices is shown inTable2 [5, p.l][l,
p. 10]. Examples of constituents within contaminant
groups are provided in Reference 1 "Technology Screen-
ing Guide for Treatment of CERCLA Soils and Sludges."
This table is based on the current available information or
professional judgment where no information was avail-
able. The proven effectiveness of the technology for a
particular site or waste does not ensure that it will be
effective at all sites or that the treatment efficiencies
achieved will be acceptable at other sites. For the ratings
used for this table, demonstrated effectiveness means
that at some scale treatability was tested to show the
technology was effective for that particular contaminant
[reference number, page number]
Printed on Recycled Paper
-------
Table 1
RCRA Codes for Wastes Treated
by Solvent Extraction
Wood Treating Wastes K001
Water Treatment Sludges K044
Dissolved Air Flotation (OAF) Float K048
Slop Oil Emulsion Solids K049
Heat Exchanger Bundles Cleaning Sludge KOSO
American Petroleum Institute (API)
Separator Sludge K051
Tank Bottoms (leaded) K052
Ammonia Still Sludge K060
Pharmaceutical Sludge K084
Decanter Tar Sludge K089
Distillation Residues K101
Table 2
Effectiveness of Solvent Extraction on
General Contaminant Groups for
Soil, Sludges, and Sediments
and matrix. The ratings of potential effectiveness or no
expected effectiveness are both based upon expert judg-
ment. Where potential effectiveness is indicated, the tech-
nology is believed capable of successfully treating the
contaminated group in a particular matrix. When the
technology is not applicable or will probably not work for a
particular combination of contaminant group and matrix, a
no expected effectiveness rating is given.
Limitations
Organically bound metals can co-extract with the tar-
get organic pollutants and become a constituent of the
concentrated organic waste stream. This is an unfavorable
occurrence because the presence of metals can restrict both
disposal and recycle options.
The presence of detergents and emulsifiers can unfa-
vorably influence extraction performance and material
throughput. Water soluble detergents found in some raw
wastes (particularly municipal) will dissolve and retain or-
ganic pollutants in competition with the extraction solvent.
This can impede a system's ability to achieve low concentra-
tion treatment levels. Detergents and emulsifiers can pro-
mote the evolution of foam, which hinders separation and
settling characteristics and generally decreases materials
throughput. Although methods exist to combat these
problems, they will add to the process cost.
When treated solids leave the extraction subsystem,
traces of extraction solvent are present [6, p.125]. The
typical extraction solvents used in currently available sys-
tems either volatilize quickly from the treated solids or
biodegrade easily. Ambient air monitoring can be em-
ployed to determine if the volatilizing solvents present a
problem.
The types of organic pollutants that can be extracted
successfully depend, in part, on the nature of the extraction
solvent. Treatability tests should be conducted to deter-
mine which solvent or combination of solvents is best suited
Contaminant Croups
6
•g
1
*
j|
1
Halogenated volatiles
Halogenated semivolatiles
Nonhalogenated volatiles
Nonhalogenated semivolatiles
PCBs
Pesticides
Dioxins/Furans
Organic cyanides
Organic corrosives
Volatile metals
Nonvolatile metals
Asbestos
Radioactive materials
Inorganic corrosives
Inorganic cyanides
Oxidizers
Reducers
Effectiveness
Soil Sludge Sediments
T
V
V
V
Q
Q
Q
Q
Q
0
Q
a
V
T
T
T
a
Q
a
Q
a
Q
Q
a
T
•
V
•
•
V
T
V
T
a
a
a
a
a
a
a
a
• Demonstrated Effectiveness: Successful treatability test at
some scale completed
T Potential Effectiveness: Expert opinion that technology will work
O No Expected Effectiveness: Expert opinion that technology will not
work
to the site-specific matrix and contaminants. In general,
solvent extraction is least effective on very high molecular
weight organics and very hydrophilic (having an affinity for
water) substances.
Some commercially available extraction systems use
solvents that are flammable, toxic, or both [7, p.2].
However, there are standard procedures used by chemical
companies, service stations, etc. that can be used to greatly
reduce the potential for accidents. The National Fire
Protection Association (NFPA) Solvent Extraction Plants
Standard (No. 36) has specific guidelines for the use of
flammable solvents [8, p. 4-60].
Technology Description
Some type of pretreatment is necessary. This may
involve physical processing and, if needed, chemical condi-
tioning after the contaminated medium has been removed
from its original location. Soils and sediments can be
removed by excavation or dredging. Liquids and pumpable
sludges can be removed and transported using diaphragm
or positive displacement pumps.
Engineering Bulletin: Solvent Extraction
-------
Any combination of material classifiers, shredders, and
crushers can be used to reduce the size of particles being
fed into a solvent extraction process. Size reduction of
particles increases the exposed surface area, thereby in-
creasing extraction efficiency. Caution must be applied to
ensure that an overabundance of fines does not lead to
problems with phase separation between the solvent and
treated solids. The optimum particle size varies with the
type of extraction equipment used.
Moisture content may affect the performance of a
solvent extraction process depending on the specific sys-
tem design. If the system is designed to treat pumpable
sludges or slurries, it may be necessary to add water to
solids or sediments to form a pumpable slurry. Other
systems may require reduction of the moisture content in
order to treat contaminated media effectively.
Chemical conditioning may be necessary for some
wastes or solvent extraction systems. For example, pH
adjustment may be necessary for some systems to ensure
solvent stability or to protect process equipment from
corrosion.
Depending on the nature of the solvent used, solvent
extraction processes may be divided into three general
types. These include processes using the following types of
solvents: standard, liquefied gas (LC), and critical solution
temperature (CST) solvents. Standard solvent processes
use alkanes, alcohols, ketones, or similar liquid solvents at
or near ambient temperature and pressure. These types of
solvents are used to treat contaminated solids in much the
same way as they are commonly used by analytical labora-
tories to extract organic contaminants from environmental
samples. LC processes use propane, butane, carbon diox-
ide, or other gases which have been pressurized at or near
ambient temperature. Systems incorporating CST solvents
utilize the unique solubility properties of those solvents.
Contaminants are extracted at one temperature where the
solvent and water are miscible and then the concentrated
contaminants are separated from the decanted liquid frac-
tion at another temperature where the solvent has minimal
solubility in water. Triethylamine is an example of a CST
solvent. Triethylamine is miscible in water at temperatures
less than 18°C and only slightly miscible above this tem-
perature.
A general schematic diagram of a standard solvent
extraction process is given in Figure 1 [9, p.5]. These
systems are operated in either batch or continuous mode
and consist of four basic process steps: (1) extraction, (2)
separation, (3) desorption, and (4) solvent recovery.
In the first step, solids are loaded into an extraction
vessel and the vessel is purged with an inert gas. Solvent is
then added and mixed with the solids. Designs of vessels
used for the extraction stage vary from countercurrent,
continuous-flow systems to batch mixers. The ratio of
solvent-to-solids also varies, but normally remains within a
range from 2:1 to 5:1. Solvent selection may also be a
Figure 1
General Schematic of a Standard Solvent Extraction Process
Contaminated Media
(pretreatment may
be necessary)
Solvent Make-up
Solvent
with Organic
Contaminants
Clean
Solvent
Concentrated
Contaminants
Decontaminated
Solids plus
Residual Solvent
Desorption
(Raffinate
Stripping)
(3)
Clean
Solvent
Decontaminated
- Solids
Engineering Bulletin: Solvent Extraction
-------
consideration. Ideally, a hydrophilic (having an affinity for
water) solvent or mixture of hydrophilic/hydrophobic (lack-
ing an affinity for water) solvents is mixed with the solids.
This hydrophilic solvent or solvent mixture will dewater the
solids and solubilize organic materials. Subsequent extrac-
tions may use only hydrophobic solvents. The contact time
and type of solvent used are contaminant-specific and are
usually selected during treatability studies.
Depending on the type of contaminated medium be-
ing treated, three phases may exist in the extractor: solid,
liquid, and vapor. Separation of solids from liquids can be
achieved by allowing solids to settle and pumping the
contaminant-containing solvent to the solvent recovery
system. If gravity separation is not sufficient, filtration or
centrifugation may be necessary. Residual solids will nor-
mally go through additional solvent washes within the
same vessel (for batch systems) or in duplicate reaction
vessels until cleanup goals are achieved. The settled solids
retain some solvent which must be removed. This is often
accomplished by thermal desorption.
Solvent recovery occurs in the final process step. Con-
taminant-laden solvent, along with the solvent vapors re-
moved during the desorption or raffinate stripping stage,
are transferred to a distillation system. To facilitate separa-
tion through volatilization and condensation, low boiling
point solvents are used for extraction. Condensed solvents
are normally recycled to the extractor; this conserves sol-
vent and reduces costs. Water may be evaporated or
discharged from the system, and still bottoms, which con-
tain high boiling point contaminants, are recovered for
future treatment.
In Figure 2, a general schematic diagram of an LC
extraction process is shown [9, p.7]. The same basic steps
associated with standard solvent processes are used with LC
systems; however, operating conditions are different. In-
creased pressure and temperature are required in order for
the solvent to take on LC characteristics.
Pumps or screw augers move the contaminated feed
through the process. In the extractor, the slurry is vigor-
ously mixed with the hydrophobic solvent. The extraction
step can involve multiple stages, with feed and solvent
moving in countercurrent directions.
The solvent/solids slurry is pumped to a decanting tank
where phase separation occurs. Solids settle to the bottom
of the decanter and are pumped to a desorber. Here, a
reduction in pressure vaporizes the solvent, which is re-
cycled, and the decontaminated slurry is discharged.
Contaminated solvent is removed from the top of the
decanter and is directed to a solvent recovery unit. A
reduction of pressure results in separating organic contami-
nants from the solvent. The organic contaminants remain
in the liquid phase and the solvent is vaporized and re-
moved. The solvent is then compressed and recycled to the
extractor. Concentrated contaminants are removed for
future treatment.
CST processes use extraction solvents for which solubil-
ity characteristics can be manipulated by changing the
temperature of the fluid. Such solvents include those
binary (liquid-liquid) systems that exhibit an upper CST
(sometimes referred to as upper consolute temperature), a
Figure 2
General Schematic of an LG Solvent Extraction Process
Clean Solvent
Contaminated Media
(pretreatment may -4
be necessary)
Extraction
(1)
Separation
(2)
Contaminated
Solvent
Decontaminated
Media plus
Residual Solvent
Desorption
(3)
: Compressor/Pump
Decontaminated
Media
Solvent
Recovery
(4)
Clean
Solvent
Concentrated
Contaminants
Clean Solvent
Solvent Make-up
Engineering Bulletin: Solvent Extraction
-------
Figure 3
General Schematic of a CST Solvent Extraction Process
Contaminated
Media (pre- m
treatment may
be necessary)
Extraction _„ ,
(D
(
Xvent
Jj
\
Separation
(2)
Decontaminated
Solids plus
Residual Solvent '
1
Desorptkxi
(3)
1 ^ Decent
Refrigeration ^ Stifnis
SOK
Conta
Solve
Wate
^
Solve
Vapc
aminate
/ent
minated
nt plus
art-*-
Here
l
nt
IT
Deca
(4
Dontam
Solvent
nated
Decanter
(4)
\
Water _
*\fc
)*
Water
nter
)
1
Conde
(4
riser
Solvent plus
StriDDino ***** Watl
(4) ^
I ^ Concentrated
" Contaminants
solvent plus
Stripping Residual Water
(4) *•
^ Treated
Water
Solvent plus
Residual Water
Solvent Make-up
lower CST (sometimes referred to as lower consolute tem-
perature), or both. For such systems, mutual solubilities of
the two liquids increase while approaching the CST. At or
beyond the CST, the two liquids are completely miscible in
each other. Figure 3 is a general schematic of a typical
lower CST solvent extraction process. Again, the same four
basic process steps are used; however, the solvent recovery
step consists of numerous unit operations [9, p.8].
Process Residuals
Three main product streams are produced from solvent
extraction processes. These include treated solids, concen-
trated contaminants (usually the oil fraction), and sepa-
rated water. Each of these streams should be analyzed to
determine its suitability for recycle, reuse, or further treat-
ment before disposal. Treatment options include: incin-
eration, dehalogenation, pyrolysis, etc.
Depending on the system used, the treated solids may
need to be dewatered, forming a dry solid and a separate
water stream. The volume of product water depends on the
inherent dewatering capability of the individual process, as
well as the process-specific requirements for feed slurrying.
Some residual solvent may remain in the soil matrix. This
can be mitigated by solvent selection, and if necessary, an
additional separation stage. Depending on the types and
concentrations of metal or other inorganic contaminants
present, post-treatment of the treated solids by some other
technique (e.g., solidification/stabilization) may be neces-
sary. Since the organic component has been separated,
additional solids treatment should be simplified.
The organic solvents used for extraction of contami-
nants normally will have a limited effect on mobilizing and
removing inorganic contaminants such as metals. In most
cases, inorganic constituents will be concentrated and
remain with the treated solids. If these remain below
cleanup levels, no further treatment may be required.
Alternatively, if high levels of teachable inorganic contami-
nants are present in the product solids, further treatment
such as solidification/stabilization, soil washing, or disposal
in a secured landfill may be required. The exception here
is organically bound metals. Such metals can be extracted
and recovered with the concentrated contaminant (oil)
fraction. High concentrations of specific metals, such as
lead, arsenic, and mercury, within the oil fraction can
restrict disposal and recycle options.
Concentrated contaminants normally include organic
contaminants, oils and grease (O&G), naturally occurring
organic substances found in the feed solids, and some
extraction fluid. Concentration factors may reduce the
Engineering Bulletin: Solvent Extraction
-------
overall volume of contaminated material to 1 /10,000 of the
original waste volume depending on the volume of the total
extractable fraction. The highly-concentrated waste stream
which results is either destroyed or collected for reuse.
Incineration has been used for destruction of this fraction.
Dechlorination of contaminants such as PCBs remains un-
tried, but is a possible treatment. Resource recovery may
also be a possibility for waste streams which contain useful
organic compounds.
Use of hydrophilic solvents with moisture-containing
solids produces a solvent/water mixture and clean solids.
The solvent and water mixture are separated from the solids
by physical means such as decanting. Some fine solids may
be carried into the liquid stream. The solvent is normally
separated from the water by distillation [10]. The water
produced via distillation will contain water-soluble con-
taminants from the feed solids, as well as trace amounts of
residual solvent and fines which passed through the sepa-
ration stage. If the feed solids were contaminated with
emulsifying agents, some organic contaminants may also
remain with the water fraction. Furthermore, the volume of
the water fraction can vary significantly from one site to
another, and with the use of dewatering as a pretreatment.
Hence, treatment of this fraction is dependent upon the
concentration of contaminants present in the water and the
flowrate and volume of residual water. In some cases, direct
discharge to a publicly owned treatment works (POTW) or
stream may be acceptable; alternatively, onsite aqueous
treatment systems may be used to treat this fraction prior to
discharge.
Solvent extraction units are designed to operate with-
out air emissions. Nevertheless, during a recent SITE
Demonstration Test, solvent concentrations were detected
in 2 of 23 samples taken from the offgas vent system [11].
Corrective measures were taken to remedy this. In addi-
tion, emissions of dust and fugitive contaminants could
occur during excavation and materials handling opera-
tions.
Site Requirements
Solvent extraction units are transported by trailers.
Therefore, adequate access roads are required to get the
units to the site. Typical commercial-scale units of 25 to
125 tons per day (tpd) require a setup area of 1,500 to
10,000 square feet [12]. NFPA recommends an exclusion
zone of 50 feet around solvent extraction systems operating
with flammable solvents [8, p. 4-61].
Standard 440V three-phase electrical service is needed.
Depending on the type of system used, between 50 and
10,000 gallons per day (gpd) of water must be available at
the site [12]. The quantity of water needed is vendor and
site specific.
Contaminated soils or other waste materials are haz-
ardous and their handling requires that a site safety plan be
developed to provide for personnel protection and special
handling measures. Storage should be provided to hold the
process product streams until they have been tested to
determine their acceptability for disposal or release. De-
pending upon the site, a method to store waste that has
been prepared for treatment may be necessary. Storage
capacity requirements will depend on waste volume.
Onsite analytical equipment for conducting O&G
analyses and a gas chromatograph capable of determining
site-specific organic compounds for performance assess-
ment will shorten analytical turnaround time and provide
better information for process control.
Performance Data
Full-scale and pilot-scale performance data are cur-
rently available from only a few vendors: CF Systems,
Resources Conservation Company (RCC), Terra-Kleen Cor-
poration, and Dehydro-Tech Corporation. Lab-scale per-
formance data are also available from these and other
vendors. Data from Superfund Innovative Technology
Evaluation (SITE) demonstrations are peer-reviewed and
have been acquired in independently verified tests with
stringent quality standards. Likewise, performance data
Table 3
Contaminant Concentrations in Typical Solids
Treated by CF Systems' Process at Port Arthur,
Texas Refinery
Compound
Benzene
Ethylbenzene
Toluene
Xylenes
Naphthalene
Phenanthrene
2-Methylphenol
Anthracene
Benzo(a)anthracene
Pyrene
Chrysene
Benzo(a)pyrene
Phenol
4-Methylphenol
Bis(2-E.H.)phthalate
Di-n-butyl phthalate
mg/kg (ppm)
BDL
BDL
BDL
1.5
2.2
3.4
BDL
BDL
BDL
1.6
BDL
BDL
BDL
BDL
BDL
BDL
BOAT
14
14
14
22
42
34
6.2
28
28
36
15
12
3.6
6.2
7.3
3.6
BOL below detection limits.
Engineering Bulletin: Solvent Extraction
-------
from remedial actions at Superfund sites or EPA sponsored
treatability tests are assumed to be valid. The quality of
other data has not been determined.
The CF Systems' 25-tpd commercial unit treated refin-
ery sludge at Port Arthur, Texas, and operated with an on-
line availability of greater than 90 percent. Extraction
efficiencies for BTX and polynuclear aromatic hydrocarbon
(PAH) compounds were greater than 99 percent. As dem-
onstrated by Table 3, the typical level of organics in the
treated solids met or exceeded the EPA Best Demonstrated
Available Technology (BOAT) standards required for these
listed refinery wastes [13].
Pilot-scale activities include the United Creosoting Su-
perfund Site treatability study and the SITE demonstration
at New Bedford Harbor, Massachusetts. During the spring
of 1989, CF Systems conducted a pilot-scale treatability
study for EPA Region VI and the Texas Water Commission at
the United Creosoting Superfund Site in Conroe, Texas. The
treatability study's objective was to evaluate the effective-
ness of the CF Systems process for treating soils contami-
nated with pentachlorophenol (PCP), dioxins, and creo-
sote-derived organic contaminants, such as PAHs. Treat-
ment data from the field demonstration (Table 4) show that
the total PAH concentration in the soil was reduced by more
than 95 percent. Untreated soil had total PAH concentra-
tions ranging from 2,879 to 2,124 mg/kg [13].
The SITE demonstration was conducted during the fall
Table 4
CP Systems' Performance Data at United Creosote
Superfund Site
Table 5
Extraction of New Bedford Harbor Sediments
Using CF Systems' Process
Compound
PAHs
Acenaphthene
Acenaphthylene
Anthracene
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(g,h,i)perylene
Benzo(k)fluoranthene
Chrysene
Dibenzo(a, h)anthracene
Fluoranthene
Fluorene
lndeno(1 ,2,3-cd)pyrene
Naphthalene
Phenanthrene
Pyrene
Total PAH concentration
feed
Soil
(mg/kg)
360
15
330
100
48
51
20
50
110
ND
360
380
19
140
590
360
2879
Treated
Soil
(mg/kg)
3.4
3.0
8.9
7.9
12
9.7
12
17
9.1
4.3
11
3.8
11
1.5
13
11
122.6
Reduction
(percent)
99
80
97
92
75
81
40
66
92
NA
97
99
58
99
98
97
96
Testt
1
2
3
Initial PCB
Concentration
(ppm)
350
288
2,575
Final KB
Concentration
(Pfm)
8
47
200
Reduction
(Percent)
98
84
92
Number of
Passes
Through
Extractor
9
1
6
Table 6
B.E.S.T.* Process Data from the General Refining
Superfund Site
Metals
As
Ba
Cr
Pb
Se
Initial
Concentration
(mg/kg)
<0.6
239
6.2
3,200
<4.0
Product
Solids Metal
(ppm)
<0.5
410
21
23,000
<5.0
rap
Levels
(ppm)
<0.0
<0.03
<0.05
5.2
0.008
Notes: mg/kg on a dry weight basis. ND indicates not
detected. NA indicates not applicable.
of 1988 to obtain specific operating and cost information
for making technology evaluations for use at other Super-
fund sites. Under the SITE Program, CF Systems demon-
strated an overall PCB reduction of more than 90 percent
(see Table 5) for harbor sediments with inlet concentrations
up to 2,575 ppm [14, p.6]. An extraction solvent blend of
propane and butane was used in this demonstration.
The ability of the RCC full-scale B.E.S.T.® process to
separate oil feedstock into product fractions was evaluated
by the EPA at the General Refining Superfund Site near
Savannah, Georgia, in February 1987. The test was con-
ducted with the assistance of EPA's Region X Environmental
Services Division in cooperation with EPA's Region IV Emer-
gency Response and Control Branch [15, p.l]. The site was
operated as a waste oil reclamation and re-refining facility
from the early 1950s until 1975. As a result of those
activities, four acidic oily sludge ponds with high levels of
heavy metals (Pb= 200 to 10,000 ppm, Cu= 83 to 190 ppm)
and detectable levels of PCBs (2.9 to 5 ppm) were pro-
duced. The average composition of the sludge from the
four lagoons was 10 percent oil, 20 percent solids, and 70
percent water by weight [15, p.l 3]. The transportable 70-
tpd B.E.S.T.® unit processed approximately 3,700 tons of
sludge at the General Refining Site. The treated solids from
this unit were backfilled to the site, product oil was recycled
as a fuel oil blend, and the recovered water was pH adjusted
Engineering Bulletin: Solvent Extraction
-------
Table 7
Summary of Results from the SITE Demonstraton of the RCC B.E.S.T.® Process
(Averages from Three Runs)
Transect 28 Sediment
Parameter
Concentration in Untreated Sediment, mg/kg
Concentration in Treated Solids, mg/kg
Removal from Sediment, percent
Concentration in Oil Product, mg/kg
Concentration in Water Product, mg/L
NA Not applicable.
i _, . . .
PCBs'
12.1
0.04
99.7
NA1
<0.003
PAHs
550
22
96.0
NA'
<0.01
Triethylamine
NA
45.1
NA
NA'
1.0
Transect 6 Sediment
PCBs
425
1.8
99.6
2,030
<0.001
PAHs
70,900
510
99.3
390,000
<0.01
Triethylamine
NA
103
NA
7332
2.2
not sufficient oil present for oil polishing (using the solvent evaporator to remove virtually all of the triethylamine for the oil). Excess
triethylamine was therefore left in the oil.
' This oil product was sampled following oil polishing.
and transported to a local industrial wastewater treatment
facility. Test results (Table 6) showed that the heavy metals
were mostly concentrated in the solids product fraction.
Toxicity Characteristic Leaching Procedure (TCLP) test re-
sults showed heavy metals to be in stable forms that resisted
leaching, illustrating a potential beneficial side effect when
metals are treated by the process [4, p.13].
During the summer of 1992 a SITE demonstration was
conducted to test the ability of the B.E.S.T.® system to
remove PAHs and PCBs from contaminated sediments ob-
tained from the Grand Calumet River. The pilot-scale
B.E.S.T.® system was primarily contained on two skids and
had an average daily capacity of 90 pounds of contami-
nated sediments. As Table 7 demonstrates, more than 96
percent of the PAHs and greater than 99 percent of the PCBs
initially present in the sediments collected from Transect 6
and Transect 28 of the Grand Calumet River were removed
[16].
Terra-Kleen Corporation has compiled remedial results
for its solvent extraction system at three sites; Treband
Superfund site, in Tulsa, Oklahoma; Sand Springs Substa-
tion site; Sand Springs, Oklahoma; and Pinette's Salvage
Yard Superfund site, Washburn, Maine. PCBs were the
primary contaminant at each of these sites. Table 8 summa-
rizes the performance at the Treband site. Preliminary
results from the Pinette's Salvage Yard site are given in
Table 9 [17].
The Carver-Greenfield (C-G) Process*, developed by
Dehydro-Tech Corporation, was evaluated during a SITE
demonstration at an EPA research facility in Edison, New
jersey. During the August 1991 test, about 640 pounds of
drilling mud contaminated with indigenous oil and el-
evated levels of heavy metals were shipped to EPA in
Edison, New Jersey from the PAB Oil Site in Abbeville,
Louisiana. The pilot-scale unit was trailer-mounted and
capable of treating about 100 Ibs/hr of contaminated
drilling mud. The process removed about 90 percent of the
indigenous oil (as measured by solids/oil/water analysis).
The indigenous total petroleum hydrocarbon (TPH) remov-
als were essentially 100 percent for both runs [18, p. 1].
E. S. Fox Limited has determined performance data for
the Extraksol* Process developed by Sanivan Group of
Montreal, Quebec, Canada. Performance data on contami-
nated soils and refinery wastes for the 1 ton per hour (tph)
mobile unit are shown in Table 10 [19]. The process uses
a proprietary solvent that reportedly achieved removal
efficiencies up to 99 percent (depending on the number of
extraction cycles and the type of soil) on solids with con-
taminants such as PCBs, O&G, PAHs, and PCP.
RCRA Land Disposal Restrictions (LDRs) that require
treatment of wastes to BDAT levels prior to land disposal
may sometimes be determined to be applicable or relevant
and appropriate requirements (ARARs) for CERCLA response
actions. The solvent extraction technology can produce a
treated waste that meets treatment levels set by BDAT, but
may not reach these treatment levels in all cases. The ability
to meet required treatment levels is dependent upon the
specific waste constituents and the waste matrix. In cases
where solvent extraction does not meet these levels, it still
may, in certain situations, be selected for use at the site if a
treatability variance establishing alternative treatment lev-
els is obtained. EPA has made the treatability variance
process available in order to ensure that LDRs do not
unnecessarily restrict the use of alternative and innovative
treatment technologies. Treatability variances may be
justified for handling complex soil and debris matrices. The
following guides describe when and how to seek a treatability
variance for soil and debris: Superfund LDR Guide #6A,
"Obtaining a Soil and Debris Treatability Variance for Reme-
dial Actions" (OSWER Directive 9347.3-06FS, September
1990) [20], and Superfund LDR Guide #6B, "Obtaining a
8
Engineering Bulletin: Solvent Extraction
-------
Table 8
Terra-Kteen Soil Restoration Unit PCB Removal at
Treband Superfund Site1
Table 10
Summary of 1-tph Extrasol®
Process Performance Data
Initial
Level
(ppm)
740
810
2,500
Final
Level
(ppm)
77
3
93
Site
Coal
(ppm)
<100
<100
<100
Reduction
(percent)
89.6
99.6
96.3
1 Soil type: sand and concrete dust.
Table 9
Terra-Kleen Soil Restoration Unit PCB Removal at
Pinette's Salvage Yard NPL Site1
Initial
Level
(ppm)
41.8
76.9
381
Final
Level
(ppm)
2.7
4.31
3.59
Site
Coal
(ppm)
<5.0
<5.0
<5.0
Reduction
(percent)
93.5
94.4
99.1
1 Full scale data. Soil type: glacial till (gravel, sand, silt, and grey
marine clay).
Soil and Debris Treatability Variance for Removal Actions"
(OSWER Directive 9347.3-06BFS, September 1990) [21].
Another approach would be to use other treatment tech-
niques in series with solvent extraction to obtain desired
treatment levels.
Technology Status
As of October 1992, solvent extraction has been cho-
sen as the selected remedy at eight Superfund sites. Two of
these, General Refining, Georgia and Treband Warehouse,
Oklahoma were emergency responses that have been com-
pleted. The other sites include Norwood PCBs, Massachu-
setts; O'Conner, Maine; Pinette's Salvage Yard, Maine;
Ewan Property, New Jersey; Carolina Transformer, North
Carolina; United Creosoting, Texas [22, p. 51].
Solvent extraction systems are at various stages of
development. The following is a brief discussion of several
systems that have been identified.
CF Systems uses liquefied hydrocarbon gases such as
propane and butane as solvents for separating organic
contaminants from soils, sludges, and sediments. To date,
the CF Systems process has been used in the field at three
Superfund sites; nine petrochemical facilities and remedia-
tion sites; and a centralized treatment, storage, and dis-
Contaminant Matrix
O&C
O&G
O&C
PAH
PAH
PCB
PCB
PCP
PCP
Clayey Soil
Oily Sludge
Fuller's Earth
Clayey Soil
Oily Sludge
Clayey Soil
Clayey Soil
Porous Gravel
Activated
Carbon
In
(ppm)
1,800
72,000
31 3,000
332
240
150
54
81.4
744
Out Reduction
(ppm) (percent)
182
2,000
3,700
55
10
14
4.4
<0.21
83
89.9
97.2
98.8
83.4
95.8
90.7
91.8
99.7
88.8
Note: Treated concentrations are based on criteria to be met
and not process efficiency
posal (TSD) facility. The CF Systems solvent extraction
technology is available in several commercial sizes and the
Mobile Demonstration Unit is available for onsite treatability
studies. CF Systems has supplied three commercial-scale
extraction units for the treatment of a variety of wastes [23,
p.3-12]. A 60-tpd treatment system was designed to
extract organic liquids from a broad range of hazardous
waste feeds at EN SCO's El Dorado, Arkansas, incinerator
facility. A commercial-scale extraction unit is installed at a
facility in Baltimore, Maryland, to remove organic contami-
nants from a 20 gallons- per-minute (gpm) wastewater
stream. A PCU-200 extraction unit was installed and
successfully operated at the Star Enterprise (Texaco) refin-
ery in Port Arthur, Texas. This unit was designed to treat
listed refinery wastes to meet or exceed the EPA's BOAT
standards. A 220 tpd extraction unit is currently being
designed for use at the United Creosoting Superfund site in
Conroe, Texas.
RCC's B.E.S.T.® system uses aliphatic amines (typically
triethylamine) as the solvent to separate and recover con-
taminants in either batch or continuous operation [4, p.2].
It can extract contaminants from soils, sludges, and sedi-
ments. In batch mode of operation, a pumpable waste is
not required. RCC has a transportable B.E.S.T.® pilot-scale
unit available to treat soils and sludges. This pilot-scale
equipment was used at a Culf Coast refinery treating
various refinery waste streams and treated PCB-contami-
nated soils at an industrial site in Ohio during November of
1989. A full-scale unit with a nominal capacity of 70 tpd
was used to clean 3,700 tons of PCB-contaminated petro-
leum sludge at the General Refining Superfund Site in
Savannah, Georgia, in 1987 [16].
Terra-Kleen Corporation's Soil Restoration Unit was
developed for remedial actions involving soil, debris, and
sediments contaminated with organic compounds. The
Engineering Bulletin: Solvent Extraction
-------
Soil Restoration Unit is a mobile system which uses various
combinations of up to 14 patented solvents, depending
upon target contaminants present. These solvents are non-
toxic and not listed hazardous wastes [17].
Dehydro-Tech Corporation's C-C Process is designed
for the cleanup of Superfund sites with sludges, soils, or
other water-bearing wastes containing hazardous com-
pounds, including PCBs, polycyclic aromatics, and dioxins.
A transportable pilot-scale system capable of treating 30 to
50 Ibs/hr of solids is available. Over 80 commercial C-C
Process facilities have been licensed in the past 30 years to
solve industrial waste disposal problems. More than half of
these plants were designed to dry and remove oil from
slaughterhouse waste (rendering plants) [12].
NuKEM Development Company/ENSR developed a
technique to remove PCBs from soils and mud several years
ago. Their solvent extraction method involves acidic con-
ditions, commercially available reagents to prepare the soil
matrix for exposure to the solvent, and ambient tempera-
tures and pressures [24]. NuKEM Development Company/
ENSR is not currently marketing this technology for the
treatment of contaminated soils and sludges. Another
application being reviewed is the treatment of refinery
sludges (K wastes and F wastes). The Solvent Extraction
Process (SXP) system developed for treating these wastes
has six steps; acidification, dispersion, extraction, raffinate
solvent recovery, stabilization/filtration, and distillation. A
pilot-scale SXP system has performed tests on over 20
different sludges. According to the vendor, preliminary
cost estimates for treating 5,000 tons per year of a feed with
10 percent solids and 10 percent oil appear to be less than
S300 per ton [25].
The Extraksol* process was developed in 1984 by
Sanivan Croup, Montreal, Quebec, Canada [26, p.35]. It is
applicable to treatment of contaminated soils, sludges, and
sediments [26, p.45]. The 1-tph unit is suitable for small
projects with a maximum of 300 tons of material to be
treated. A transportable commercial scale unit, capable of
processing up to 8 tph, was constructed by E.S. Fox Ltd. At
present, the assembled unit is available for inspection at the
fabricator's facility in Welland, Ontario, Canada. [19].
The Low Energy Extraction Process (LEEP), developed
by ART International, Inc., is a patented solvent extraction
process that can be used on-site for decontaminating soils,
sludges and sediments. LEEP uses common organic sol-
vents to extract and concentrate organic pollutants such as
PCB, PAH, PCP, creosotes, and tar derived chemicals [27,
p.250]. Bench-scale studies were conducted on PCB con-
taminated soils and sediments, base neutral contaminated
soils and oil refinery sludges. ART has designed and con-
structed a LEEP Pilot Plant with a nominal solids throughput
of 200 Ibs/hr [12]. The pilot plant has been operational
since March 1992. Recently, a 13 tph (dry basis) commer-
cial facility capable of treating soil contaminated with up to
5 percent tar was completed for a former manufactured gas
plant site.
Phanix Milje, Denmark has developed the Soil Regen-
eration Plant, a 10 tph transportable solvent extraction
process. This process consists of a combined liquid extrac-
tion and steam stripping process operating in a closed loop.
A series of screw conveyors is used to transfer the contami-
nated soil through the process. Contaminants are removed
from soil in a countercurrent extraction process. A drainage
screw separates the soil from the extraction liquid. The
extraction liquid is distilled to remove contaminants and is
then recycled. The soil is steam heated to remove residual
contaminants before exiting the process [28].
Cost estimates for solvent extraction range from $50 to
$900 per ton [12]. The most significant factors influencing
costs are the waste volume, the number of extraction
stages, and operating parameters such as labor, mainte-
nance, setup, decontamination, demobilization, and lost
time resulting from equipment operating delays. Extrac-
tion efficiency can be influenced by process parameters
such as solvent used, solvent/waste ratio, throughput rate,
extractor residence time, and number of extraction stages.
Thus, variation of these parameters, in particular hardware
design and/or configuration, will influence the treatment
unit cost component but should not be a significant con-
tributor to the overall site costs.
EPA Contact
Technology-specific questions regarding solvent ex-
traction may be directed to:
Mark Meckes
U.S. EPA, Risk Reduction Engineering Laboratory
26 W. Martin Luther King Drive
Cincinnati, OH 45268
(513)569-7348
Acknowledgments
This updated bulletin was prepared for the U.S. EPA,
Office of Research and Development (ORD), Risk Reduction
Engineering Laboratory (RREL), Cincinnati, Ohio, by Sci-
ence Applications International Corporation (SAIC) under
EPA Contract No. 68-CO-0048. Mr. Eugene Harris served as
the EPA Technical Project Monitor. Mr. |im Rawe (SAIC) was
the Work Assignment Manager. He and Mr. George Wahl
(SAIC) co-authored the revised bulletin. The authors are
especially grateful to Mr. Mark Meckes of EPA-RREL, who
contributed significantly by serving as a technical consult-
ant during the development of this document. The authors
also want to acknowledge the contributions of those who
participated in the develoment of the original bulletin.
The following other Agency and contractor personnel
have contributed their time and comments by peer review-
ing the document:
Dr. Ben Blaney
Mr. John Moses
Dr. Ronald Dennis
EPA-RREL
CF Technologies, Inc.
Lafayette College
10
Engineering Bulletin: Solvent Extraction
-------
REFERENCES
1. Technology Screening Guide for Treatment of CERCLA
Soils and Sludges. EPA/540/2-88/004, U.S. Environ-
mental Protection Agency, 1988.
2. Raghavan, R., D.H. Dietz, and E. Coles. Cleaning Exca-
vated Soil Using Extraction Agents: A State-of-the-Art
Review. EPA 600/2-89/034, U.S. Environmental Protec-
tion Agency, Releases Control Branch, Edison, N|, 1988.
3. CF Systems Corporation, Marketing Brochures (no
dates).
4. Austin, Douglas A. The B.E.S.T.® Process - An Innova-
tive and Demonstrated Process for Treating Hazardous
Sludges and Contaminated Soils. Presented at 81st An-
nual Meeting of APCA, Preprint 88-6B.7, Dallas, Texas,
1988.
5. Innovative Technology: B.E.S.T.* Solvent Extraction Pro-
cess. OSWER Directive 9200.5-253FS, U.S. Environmen-
tal Protection Agency, 1989.
6. Reilly, T.R., S. Sundaresan, and J.H. Highland. Cleanup
of PCB Contaminated Soils and Sludges By A Solvent
Extraction Process: A Case Study. Studies in Environ-
mental Science, 29:125-139, 1986.
7. Weimer, L.D. The B.E.S.T.* Solvent Extraction Process
Applications with Hazardous Sludges, Soils and Sedi-
ments. Presented at the Third International Conference,
New Frontiers for Hazardous Waste Management, Pitts-
burgh, Pennsylvania, 1989.
8. Fire Protection Handbook. Fourteenth Ed. National Fire
Protection Association, 1976.
9. Guide for Conducting Treatability Studies under
CERCLA Solvent Extraction. EPA/540/R-92/016a, U.S.
Environmental Protection Agency, 1992.
10. Blank, Z. and W. Steiner. Low Energy Extraction Pro-
cess-LEEP: A New Technology to Decontaminate Soils,
Sediments, and Sludges. Presented at Haztech Interna-
tional 90, Houston Waste Conference, Houston, Texas,
May 1990.
11. Technology Evaluation Report - Resources Conservation
Company, Inc. B.E.S.T.® Solvent Extraction Technol-
ogy. EPA/540/R-92/079a U.S.Environmental Protection
Agency, 1993.
12. Vendor Information System for Innovative Treatment
Technologies (VISITT) Database, Version 1.0. U.S. Envi-
ronmental Protection Agency.
13. Site Remediation of Contaminated Soil and Sediments:
The CF Systems Solvent Extraction Technology. CF Sys-
tems, Marketing Brochure (no date).
14. Technology Evaluation Report - CF Systems Organics
Extraction System, New Bedford, MA, Volume I. EPA/
540/5-90/002, U.S. Environmental Protection Agency,
1990.
15. Evaluation of the B.E.S.T.* Solvent Extraction Sludge
Treatment Technology Twenty-Four Hour Test. EPA/
600/2-88/051, U.S. Environmental Protection Agency,
1988.
16. Applications Analysis Report - Resources Conservation
Company, Inc. B.E.S.T.® Solvent Extraction Technology.
EPA/540/AR-92/079, U.S. Environmental Protection
Agency, 1993.
17. Cash, A.B. Full Scale Solvent Extraction Remedial Re-
sults. Presented at American Chemical Society, I&EC
Division Special Symposium; Emerging Technologies for
Hazardous Waste Management, Atlanta, CA, September
21-23,1992.
18. Applications Analysis Report - The Carver-Greenfield
Process®; Dehydro-Tech Corporation. EPA/540/AR-92/
002, U.S. Environmental Protection Agency, 1992.
19. Non-Thermal Extraction of Hazardous Wastes from Soil
Matrices. ES Fox Limited, Marketing Brochure (no
date).
20. Superfund LDR Guide #6A: (2nd Edition) Obtaining a
Soil and Debris Treatability Variance for Remedial Ac-
tions. Superfund Publication 9347.3-06FS, U.S. Environ-
mental Protection Agency, 1990.
21. Superfund LDR Guide #6B: Obtaining a Soil and Debris
Treatability Variance for Removal Actions. Superfund
Publication 9347.3-06BFS, U.S. Environmental Protec-
tion Agency, 1990.
22. Innovative Treatment Technologies: Semi-Annual Status
Report (Fourth Edition). EPA542-R-92-011, U.S. Envi-
ronmental Protection Agency, 1992.
23. Applications Analysis Report - CF Systems Organics Ex-
traction System, New Bedford, MA. EPA/540/A5-90/
002, U.S. Environmental Protection Agency, 1990.
24. Massey, M.J., and S. Darian, ENSR Process for the Ex-
tractive Decontamination of Soils and Sludges. Present-
ed at the PCB Forum, International Conference for the
Remediation of PCB Contamination, Houston, Texas,
1989.
25. Chelemer, M.). ENSR's SXP System for Treating Refinery
K-Wastes: An Update. ENSR Consulting and Engineer-
ing, Marketing Brochure (no date).
26. Paquin,)., and D. Mourato. Soil Decontamination with
Extraksol. Sanivan Group, Montreal, Canada (no date),
pp. 35-47.
27. The Superfund Innovative Technology Evaluation Pro-
gram: Technology Profiles Fifth Edition. EPA/540/R-92/
077, U.S. Environmental Protection Agency, 1992.
28. Phanix Milje Cleans Contaminated Soil On-Site: In Mo-
bile Extraction Plant. Phenix Milje Marketing Informa-
tion (no date).
Engineering Bulletin: Solvent Extraction
-------
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/540/S-94/503
-------
&EPA
United States
Environmental Protection
Agency
Office of
Solid Waste and
Emergency Response
EPA/540/R-92/016b
August 1992
Guide for Conducting Treatability
Studies under CERCLA:
Solvent Extraction
Office of Emergency and Remedial Response
Hazardous Site Control Division OS-220
QUICK REFERENCE FACT SHEET
Section 121 (b) of CERCLA mandates EPA to select remedies that "utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the maximum extent practicable" and to prefer remedial actions in which
treatment that "permanently and significantly reduces the volume, toxicity, or mobility of hazardous substances, pollutants,
and contaminants is a principal element." Treatability studies provide data to support remedy selection and implementation.
They should be performed as soon as it becomes evident that the available information is insufficient to ensure the quality
of the decision. Conducting treatability studies early in the remedial investigation/feasibility study (RI/FS) process should
reduce uncertainties associated with selecting the remedy and should provide a sound basis for the Record of Decision
(ROD). Regional planning should factor in the time and resources required for these studies.
This fact sheet provides a summary of information to facilitate the planning and execution of solvent extraction remedy
screening and remedy selection treatability studies in support of the RI/FS and the remedial design/remedial action (RD/
RA) processes. Detailed information on designing and implementing remedy screening and remedy selection treatability
studies for solvent extraction is provided in the "Guide for Conducting Treatability Studies Under CERCLA: Solvent
Extraction," Interim Guidance. EPA/540/R-92/0163, August 1992.
INTRODUCTION
There are three levels or tiers of treatability studies:
remedy screening, remedy selection, and remedy design.
The "Guide for Conducting Treatability Studies Under
CERCLA: Solvent Extraction," Interim Guidance, discusses
all three levels of treatability studies. The solvent extraction
treatability guidance is one of a series of technology-
specific documents.
Remedy screening studies provide a quickand relatively
inexpensive indication of whether solvent extraction is a
potentially viable remedial technology. Remedy selection
studies provide data that permit evaluation of solvent
extraction's ability to meet expected site cleanup goals and
provide information in support of the detailed analysis of
the alternative (i.e., seven of the nine evaluation criteria
specified in EPA's RI/FS Interim Final Guidance Document,
EPA/540/G-89/004,1988. Remedy selection tests generally
have moderate costs and may require weeks to months to
complete. Remedy design testing provides quantitative
nerformance, cost, and design information for remediating
le operable unit. Remedy design studies are of moderate
to high costs and may require months to complete.
TECHNOLOGY DESCRIPTION AND PRELIMINARY
SCREENING
Technology Description
Solvent extraction is a separation technology which
uses a fluid to remove hazardous contaminants from
excavated soils, sludges, and sediments and/or
contaminated groundwater and surface water. The solvent
is chosen such that the contaminants have a higher affinity
forthe solvent than for the contaminated material. Solvent
extraction does not destroy contaminants, it concentrates
them so that they can be recycled or destroyed more cost
effectively. When contaminants are not recycled, solvent
extraction must be combined with other technologies in a
treatment train to destroy the separated, concentrated
contaminants. Solvent extraction has limited application
as a treatment technology for inorganic contaminants.
Nevertheless, solvent extraction may affect inorganic
contaminants even when the process is designed to treat
organic contaminants. The discussions in this document
are primarily related to organic contaminants.
Solvent extraction processes can be divided into
three general types based upon the type of solvent used:
-------
standard solvents, near-critical fluids/liquefied gases, and
critical solution temperature (CST) solvents. Standard
solvent processes use alkanes, alcohols, or similar liquid
solvents typically at ambient pressure. Near-critical fluid/
liquefied gas processes use butane, isobutane, propane,
carbon dioxide (CO2), or similar gases which have been
liquefied under pressure at ambient temperature. Systems
involving CST solvents use the unique solubility properties
of those compounds to extract contaminants at one
temperature where the solvent and water are miscible and
then separate the concentrated contaminants from the
water fraction at another temperature. Solvent is then
removed from the contaminants by evaporation.
Rgure 1 is a general schematic of the solvent extraction
process.
Feed preparation (1) includes moving the material to
the process where it is normally screened to remove debris
and large objects. Depending upon the process vendor
and whether the process is semi-batch or continuous, the
waste may need to be made pumpable by the addition of
solvent or water. In the extractor (2), the feed and solvent
are mixed, resulting in the dissolution of organic contaminant
into the solvent. The extracted organics are removed from
the extractor with the solvent and go to the separator (3),
where the pressure or temperature is changed, causing
the organic contaminants to separate from the solvent.
The solvent is recycled (4) to the extractor, and the
concentrated contaminants (5) are removed from the
separator.
Solvent extraction has been used as a full-scale remedy
at two CERCLA sites: (1) the Treban PCS site in Tulsa, OK t
and (2) the General Refining site in Garden City, GA."
However, the technology shows promise for treating
variety of organic contaminants commonly found &,
CERCLA sites. During fiscal year 1989, solvent extraction
was selected in combination with other technologies for
remediation of five Superfund sites having soils and
sediments contaminated with poly-chlorinated biphenyls
(PCBs), polynucleararomatic hydrocarbons (PAHs).
pentachlorophenol (PCP), and other organic compounds.
These sites are Norwood PCBs, MA; O'Conner, ME;
Pinette's Salvage Yard, ME; Ewan Property, NJ; and
United Creosoting, TX.
Prescreening Characteristics
The determination of the need for and the appropriate tier
of treatability study required is dependent on the literature
information available on the technology, expert technical
judgement and site-specific factors. The first two elements
- the literature search and expert consultation - are critical
factors of the prescreening phase in determining whether
adequate data are available or whether a treatability study is
needed.
Information on the technology applicability, the latest
performance data, the status of the technology, and sources
for further information are provided in one of a series of
engineering bulletins being prepared by U.S. EPA's Risk
Reduction Engineering Laboratory (RREL) in Cincinnati,
Ohio. |
Solvent Make-up
Contaminated Media
(pretreatment may"
be necessary)
i
Extraction
(1)
i
Solvent
Sepc
(opt
(
iration Contaminants
innah »--
2)
Clean
Solvent
Solvent
Recovery
(Distillation)
W
^ Concentrated
Contaminants
Decontaminated
Solids plus
Residual Solvent
Deso
(Raff
Strip
(2
rption
nate
aing)
I)
Clean
Solvent
Decontaminated
I — +~ Solids
Rgure 1. Generic Solvent Extraction Process
-------
A literature search should be performed to determine the
physical and chemical properties of the contaminants of
interest The most important prescreening parameters are
toe contaminant profile and concentration of contaminants.
Jbntaminant characteristics such as vapor pressure, solu-
bility, Henry's Law constant, partition coefficient, boiling
point, specific gravity, and viscosity may be important for the
design of remedy evaluation studies and related residuals
treatment systems. Tests for total organic carbon (TOG) and
total recoverable petroleum hydrocarbons give an estimate
of equilibrium partitioning arid contaminant transport be-
tween soil and water and may be useful in comparing results
to other sites with different contaminants. Particle size distri-
bution and moisture are useful for evaluating materials han-
dling and pretreatment processes. A discussion of other, less
important parameters such as pH, temperature, chemical
oxygen demand (COD), and contaminant toxicity is con-
tained in the solvent extraction guide.
If contamination exists in different soil strata or in
different media, a characterization profile should be
developed for each soil type or media. Available chemical
and physical data (including contaminant concentration
averages and ranges) and the volumes of the contaminated
soil requiring treatment should be identified. For "hot
spots", separate characterizations should be done so they
can be properly addressed in the treatability tests. Solvent
extraction may be applicable to some parts of a site, but not
to other parts.
The quantity of large rocks, debris, and other oversize
screenable material that must be removed is an important
Measurement. While this is not a laboratory" measurement
It is important to determine which treatment method is most
suitable for preparing the bulk soil or sediment for entry into
the solvent extraction process, i.e., screening to remove
large rocks, stumps, debris, and washing or crushing of
oversize materials, etc. The quantity of and degree of
contamination of water is important for design of ultimate
treatment systems. The water could be the media to be
treated or could be associated with a soil/sludge media.
Technology Limitations
Solvent extraction limitations may be defined as
characteristics that hinder cost-effective treatment of the
contaminated media with specific processes. The limitation
may be due to the contaminant (incompatibility with the
selected solvents or complex mix of contaminants), the
process, or the media. Several extraction stages may be
required in some cases to meet the site cleanup goals.
Difficulties may be encountered in recycling spent solvents.
Hydrophobic and hydrophilic contaminants may be difficult
to extract with the same solvent. The contaminated media
might require substantial pretreatment.
Complex mixtures of contaminants in the waste media,
such as a mixture of metals, non-volatile organics. semi-
volatile organics, etc. may make the design or selection of
a suitable solvent extraction system that will remove all the
Different types of contaminants difficult. Organically bound
metals can co-extract with the target organic pollutants and
restrict disposal and recycle options. The presence of
emulsifiers 'and detergents can adversely affect the
extraction performance by competing with the extraction
solvent for retention of the organic pollutants. High moisture
can interfere with the efficiency of some solvents, limiting
the application of certain solvent extraction processes.
Advantages and disadvantages exist among the various
types of solvent extraction processes. The primary
differences include the following: ability to handle fines or
high clay content, ability to handle a wide variety of organic
contaminants, the ease of phase separation after extraction,
and the energy requirements.
THE USE OF TREATABIUTY STUDIES IN REMEDY
EVALUATION
Treatability studies should be performed in a systematic
fashion to ensure that the data generated can support the
remedy evaluation process. The results of these studies
must be combined with other data to fully evaluate the
technology.
There are three levels or tiers of treatability studies:
remedy screening, remedy selection, and remedy design.
Some or all of the levels may be needed on a case-by-case
basis. The need for and the level of treatability testing are
management-based decisions in which the time and cost
of testing are balanced against the risks inherent in the
decision (e.g., selection of an inappropriate treatment
alternative). These decisions are based on the quantity
and quality of data available and on other decision factors
(e.g., state and community acceptance of the remedy, new
site data).
Technologies may be evaluated first at the remedy
screening level and progress through the remedy selection
to the remedy design level. A technology may enter,
however, at whatever level is appropriate based on
experience with the technology, contaminants of concern,
and site-specific factors. Figure 2 shows the relationship
of three levels of treatability study to each other and to the
RI/FS process.
Remedy Screening
Remedy screening, the first tier of testing, is used to
determine the ability of a technology to treat a contaminated
soil using simple laboratory tests. Approximately 5 kg of
sample are extracted for several hours in a rotary shaker
or other device using a hydrophilic solvent such as acetone
or methanol. The residual solids are then extracted in a
hydrophobic solvent such as hexane or kerosene. The
mean contaminant concentration in the solids or water
fraction is determined from duplicate samples before and
after extraction. These studies are generally low cost (e.g.,
< $30,000) and usually require one or more days to
complete. Remedy screening tests are generic and can be
performed at any laboratory with the proper equipment and
qualified personnel. This tier is occasionally skipped for
evaluation of solvent extraction.
-------
Remedy Selection
Remedy selection, the second tier of testing, is used to
evaluate the technology's performance on a contaminant-
specific basis for an operable unit. A total of 5 kilograms or
more of sample are extracted, typically using vendor-
specific solvents and equipment. The test design is based
on remedy screening tests or information from the
prescreening search. Normally, triplicate samples are taken
from both the solvent and the extracted medium (soil,
water, etc.) These studies generally have moderate costs
(e.g., $20,000 to $120,000) and may require several months
or more to plan, obtain samples, and execute. They yield
data that verify the technology's ability to meet expected
cleanup goals and provide information in support of the
detailed analysis of alternatives in the CERCLA Feasibility
Study (FS).
The remedy selection tier of solvent extraction testing
consists of bench-scale tests and/or pilot tests. Typically,
these tests will be vendor-specific. Sufficient experimental
controls are needed such that a quantitative mass balance
can be achieved. The key question to be answered during
remedy selection testing is whether the treated media will
meet the cleanup goals for this site. The exact removal
efficiency or acceptable residual contaminant level specified
as the goal for the remedy selection test is site-specific.
Typically, a remedy design study would follow a successful
remedy selection study, after the ROD.
Remedy Design
Remedy design testing is the third tier of testing. In this
tier, pilot tests provide quantitative performance data to
confirm the feasibility of solvent extraction based on target
cleanup goals. These tests also produce information to
refine cleanup time estimates and cost predictions and to
design a full-scale system. This testing also produces the
remaining data required to optimize performance. Specific
information includes the identification of pretreatment
requirements and material handling concerns and
determining the number of extraction sequences required.
These studies are of moderate to high cost (e.g., $100,000
to $500,000) and require several months to complete the
testing. As with the other tiers, planning, analysis, and
report writing will add to the duration of the study. For
Remedial Investigation/
Feasibility Study (RI/FS)
Identification
of Alternatives
Scoping
- the -
RI/FS
Literature
Screening
and
Treatability
Study Scoping
Site
Characterization
and Technology
Screening
REMEDY
SCREENING
to Determine
Technology Feasibility
Record of
Decision
(ROD)
Remedy
Selection
Remedial Design/
Remedial Action •
(RD/RA)
Evaluation
of Alternatives
REMEDY SELECTION
to Develop Performance
and Cost Data
Implementation
of Remedy
REMEDY DESIGN
to Develop Scale-Up, Design,
and Detailed Cost Data
Figure 2. The Role of Treatability Studies in the RI/FS and RD/RA Process
-------
complex sites (e.g.. sites with different types-or
"concentrations of contaminants in different media such as
soil, sludges, and water), longer testing periods may be
required, and costs will be higher. Remedy design tests
yield data that verify performance to a higher degree than
remedy selection and provide detailed design information.
They are performed during the remedy implementation
phase of the site cleanup, after the ROD and evaluation of
alternatives.
TREATABIUTY STUDY WORK PLAN
Carefully planned treatability studies are necessary to
ensure that the data generated are useful for evaluating
the validity or performance of the technology. The Work
Plan sets forth the contractor's proposed technical approach
to the tasks outlined in the RPM's Work Assignment. It also
assigns responsibilities, establishes the project schedule,
and estimates costs. The Work Plan must be approved by
the RPM before work begins. A suggested organization of
the solvent extraction treatability study Work Plan is provided
in the "Guide for Conducting Treatability Studies Under
CERCLA: Solvent Extraction".
Test Objectives and Goals
The overall solvent extraction treatability study
objectives must meet the specific needs of the RI/FS.
There are nine evaluation criteria specified in the EPA's Rl/
PS Interim Final Guidance Document. Treatability studies
can provide data from which seven of these criteria may be
evaluated.
Treatability study goals are the specific cleanup
standards or removal rates designed to meet the test
objectives. Setting goals for the treatability study is critical
to the ultimate usefulness of its results. These goals must
be well defined before the study is performed. Each tier or
phase of the treatability study program requires appropriate
performance goals. For example, remedy screening tests
could answer the question, "Will solvent extraction reduce
contaminants to the cleanup level, if known, or by a
sufficient percentage (e.g., 50 to 70 percent)? The remedy
selection tests measure whether the process could reduce
contamination to below the anticipated performance criteria
to be specified in the ROD. In the absence of specific
cleanup goals, an arbitrary reduction (e.g., 90 to 99 percent)
may be chosen to indicate potential usefulness.
Laboratory-scale tests are used for remedy screening.
Remedy screening goals should simply require that the
contaminant of interest shows a reduction in concentration
in the soil of approximately 50 to 70 percent. The goal is
to show solvent extraction has the potential to work at the
site. Occasionally, sufficient information exists about soil
conditions and contaminant solubility in various solvents
so that remedy screening tests will not be necessary.
Bench-scale tests for remedy selection can determine
if ultimate cleanup levels can be met. When solvent
extraction'is-the primary nreatment technology/the^
suggested cleanup goals are typically set by the ARARs.
Pilot-scale testing occasionally is used during remedy
selection. Pilot-scale tests usually involve the operation of
a mobile treatment unit onsite for a period of 1 to 2 months.
For more complex sites (e.g., sites with different types of
contaminants in separate areas), longer overall testing
periods may be required. The goal of pilot-scale testing is
to confirm that the cleanup levels and treatment times
estimated for site remediation are achievable.
Experimental Design
Careful planning of experimental design and procedures
are required to produce adequate treatability study data.
The experimental design must identify the critical
parameters and determine the number of replicate tests
necessary. System design, test procedures, and test
equipment will vary among vendors. The information
presented in this section provides an overview of the test
equipment and procedures as these relate to each type of
test.
Screening tests can be rapidly performed in onsite or
offsite laboratories using standard laboratory glassware or
specially designed laboratory-scale extractors to evaluate
the potential performance of solvent extraction as an
alternative technology. Typically, one or more hydrophobia
and one or more hydrophilic solvents are tested. At this
level of testing the experimental design should not be
vendor-specific. Contaminant characteristics to examine
during remedy screening include solubility in various
solvents. Vapor pressure and Henry's Law constants are
useful for evaluating solvent recovery methods. Observe
whether an emulsion forms, either at the top or the bottom.
Observe and time the solids settling rate and depth. The
rate and the relative volume of the settling material will
provide some indication of the potential for solids separation.
Removal efficiency can be estimated by analyzing the
separated solids for selected indicator contaminants of
concern. It is usually not cost-effective to analyze for all
contaminants at this level of testing. Check for other
contaminants later in the solids or water fraction from
remedy selection tests.
A remedy selection test design should be geared to the
type of system expected to be used in the field (I.e.,
standard solvents, near-critical fluids/liquefied gases, or
CST solvents). Solvent-to-solids ratios should be planned
using the results from the laboratory screening tests, if they
were performed. Remedy selection tests may use the
same equipment as the remedy screening tests or may
require that additional equipment be available, depending
upon the process being evaluated. The tests are run under
more controlled conditions than the remedy screening
tests. The removal efficiency is measured under variable
extraction conditions, which can include the addition of
several solvents or an entrainer, heated solvents, pH
adjustment, and use of supercritical or near-critical
conditions. More precision is used in weighing, mixing, and
phase separation. There is an associated increase in QA/
-------
QC costs. Wetsoils and sediments may require dewatering
before treatment. Chemical analyses are frequently
performed on the solvent fraction as well as on the cleaned
solids fraction. Concentration measurements should be
taken after each cycle or batch so that the cost of each
cycle versus the percentage removal can be calculated
and the impact of process variables on extraction efficiency
can be quantified. This series of tests is considerably more
costly than remedy screening tests, so only samples
showing promise in the remedy screening phases should
be carried forward into the remedy selection tier.
Bench-scale testing is usually sufficient for remedy
selection, but there are instances where additional pilot-
scale testing is warranted. If foaming problems occurred
during remedy screening or bench-scale testing, pilot-
scale testing should be used to solve any problems before
full-scale remediation. Pilot-scale testing may be necessary
in order to obtain community acceptance. A pilot-scale or
short-term run with full-scale equipment may be used for
large sites in order to better define cost estimates for the
complete remediation.
The decision on whether to perform remedy selection
testing on hot spots or composite samples is difficult and
must be made on a site-by-site basis. Hot spot areas
should be factored into the test plan if they represent a
significant portion of the waste site. However, It is more
practical to test the specific waste matrix that will be fed to
the f ull-scaJe system over the bulk of its operating life. If the
character of soils or sediments change radically (e.g., from
day to sand) over the depth of contamination, then tests
should be designed to separately study system performance
on each soil type.
SAMPLING AND ANALYSIS PLAN
The Sampling and Analysis Plan (SAP) consists of two
parts—the Reid Sampling Plan (FSP) and the Quality
Assurance Project Plan (QAPjP). The RI/FS requires a
SAP for all field activities. The SAP ensures that samples
obtained for characterization and testing are representative
and that the quality of the analytical data generated is
known and appropriate. The SAP addresses field sampling,
waste characterization, and sampling and analysis of the
treated wastes and residuals from the testing apparatus or
treatment unit. The SAP is usually prepared after Work
Plan approval.
Reid Sampling Plan
The FSP component of the SAP describes the sampling
objectives; the type, location, and number of samples to be
collected; the sample numbering system; the equipment
and procedures for collecting the samples; the sample
chain-of-custody procedures; and the required packaging,
labeling, and shipping procedures.
Quality Assurance Project Plan
The QAPjP should be consistent with the overall
objectives of the treatability study.
At the remedy screening level the QAPjP need not be
overly detailed. The intended purpose of remedy screening
tests is to determine if the contaminant concentration
decreases by approximately 50 to 70 percent. Accurate
calibration of the gas chromatograph with the target
compounds is required. Duplicate tests are normally
required at the remedy screening level to assure the
reproducibility of the data.
The purpose of the remedy selection treatability study
is to determine whether solvent extraction can meet cleanup
goals and provide information to support the detailed
analysis of alternatives (i.e., seven of the nine evaluation
criteria). A higher level of QA/QC is required because the
consequences of an incorrect decision are more serious at
this level. Concentrations of the target contaminants in the
soil should be verified by employing triplicate samples to
provide a measure of data reproductibility. Recovery of
contaminants from the sample is estimated by using matrix
spikes. The QAPjP should address the measurement of
critical variables, including the concentrations of target
compounds in the initial and treated soil.
The methods for analyzing the treatability study samples
are the same as those for chemical characterization of field
samples. Preference is given to methods in Test Methods
for Evaluating Solid Waste," SW-846,3rd. Ed., November
1986. Other standard methods may be used, as appropriate. '•>
Methods other than gas chromatography/mass
specstroscopy (GC/MS) techniques are recommended to
conserve costs when possible.
TREATABIUTY DATA INTERPRETATION
To property evaluate solvent extraction as a remediation
alternative, the data collected during remedy screening
and remedy selection phases must be compared to the test
goals and other criteria that were established before the
tests were conducted. In remedy screening treatability
studies the contaminant concentration in the solids or
water fraction before extraction is compared to the
contaminant concentration in the same fraction after
extraction. A removal of approximately 50 to 70 percent of
the contaminants during the test indicates additional
treatability studies are warranted. Before and after
concentrations can normally be based on duplicate samples
at each time period. The mean values are compared to
assess the success of the study. Contaminant
concentrations can also be determined for water and
solvent fractions. However, these additional analyses add
to the cost of the treatability test and may not be needed.
-------
Remeay screening tests can sometimes be skipped
when information about the contaminant solubilities in the
selected solvent is sufficient to decide whether remedy
selection studies will be useful. This information should be
solvent- and contaminant-specific and may or may not be
applicable to other sites.
In remedy selection, contaminant concentrations in
the contaminated matrix before and after solvent extraction
are typically measured in triplicate. Contaminant levels
after treatment which meet site cleanup standards indicate
solvent extraction has the potential to remediate the site. A
reduction in the mean concentration to cleanup levels, if
known, or by approximately 90 to 99 percent indicates
solvent extraction is potentially useful in site remediation.
A higher QA level is required with this tier of testing. A
number of other factors must be evaluated before deciding
to proceed with this technology to the evaluation of
alternatives.
The design parameters for the solvent extraction
process include material throughput and optimum solvent
usage in gallons per dry ton of solids or gallons of water. It
is important to estimate the volume and physical and
chemical characteristics of each fraction to design treatment
systems and estimate disposal costs. The ability to cost-
effectively recover used solvent is also important for cost
and performance estimates. Removal efficiency measured
as a function of the number of extraction stages can be
used to determine the stages required to reach cleanup
levels.
The final concentration of contaminants in the recovered
(clean) solids fraction, in the solvents, in solvent distillation
bottoms, and in water fractions are important to evaluating
the feasibility of solvent extraction. The selection of
technologies to treat the solvent or solvent still bottoms and
water fraction from soil/sludges depends upon the types
and concentrations of contaminants present. The amount
of volume reduction achieved in terms of contaminated
media is also important to the selection of solvent extraction
as a potential remediation technology.
TECHNICAL ASSISTANCE
Additional literature and consultation with experts are
critical factors in determining the need for and ensuring the
usefulness of treatability studies. A reference list of
sources on treatability studies is provided in the "Guide for
Conducting Treatability Studies Under CERCLA: Solvent
Extraction."
It is recommended that a Technical Advisory Committee
(TAG) be used. This committee includes experts on the
technology who provide technical support from the scoping
phase of the treatability study through data evaluation.
Members of the TAG may include representatives from
EPA (Region and/or ORD), other Federal Agencies, States,
and consulting firms.
OSWER/ORD operate the Technical Support Project
(TSP) which provides assistance in the planning,
performance, and/or review of treatability studies. For
further information on treatability study support or the TSP,
please contact:
Mr. Michael Gruenfeld
U.S. Environmental Protection Agency
Release Control Branch
Risk Reduction Engineering Laboratory
2890 Woodbridge Ave.
Building 10,2nd Floor
Edison, NJ 08837
(908)321-6625
FOR FURTHER INFORMATION
In addition to the contacts identified above, the
appropriate Regional Coordinator for each Region located
in the Hazardous Site Control Division/Office of Emergency
and Remedial Response or the CERCLA Enforcement
Division/Office of Waste Programs Enforcement should be
contacted for additional information or assistance.
ACKNOWLEDGEMENTS
This fact sheet and the corresponding guidance
document were prepared for the U.S. Environmental
Protection Agency, Office of Research and Development
(ORD), Risk Reduction Engineering Laboratory (RREL),
Cincinnati, Ohio by Science Applications International
Corporation (SAIC) under Contract No. 68-C8-0062. Mr.
Dave Smith served as the EPA Technical Project Monitor.
Mr. Jim Rawe was SAIC's Work Assignment Manager and
the primary author. Mr. George Wahl of SAIC assisted in
writing these documents. The authors are especially
grateful to Mr. MarkMeckes of EPA, RREL who contributed
significantly by serving as a technical consultant during the
development of this document.
Many other Agency and independent reviewers have
contributed their time and comments by participating in the
expert review meetings and/or peer reviewing the guidance
document.
•us.o«
I Pitting Ode
-------
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/540/R-92/016b
-------
Section 13
-------
THERMAL TREATMENTS
STUDENT PERFORMANCE OBJECTIVES
At the conclusion of this unit, students will be able to:
1. Identify three destructive and two nondestructive thermal
treatments
2. Describe four combustion factors that are needed for an
incinerator to properly operate
3. Define destruction removal efficiency as it pertains to
incineration
4. Describe the following incinerator designs:
a. Rotary kiln
b. Infrared
5. Describe wet-air oxidation and the type of waste this process
is most commonly used to treat
6. Describe low-temperature desorption with catalytic oxidation
7. Describe low-temperature desorption with condensation
collection
8. Describe the distillation process and its uses.
NOTE: Unless otherwise stated, the conditions for
performance are using all references and materials
provided in the course, and the standards of
performance are without error.
7/95
-------
THERMAL
TREATMENTS
THERMAL TREATMENTS
• Destructive
- Incinerators
- Wet air oxidation
- Low-temperature desorption
with oxidation
THERMAL TREATMENTS
• Nondestructive
- Low-temperature desorption
with condensation
- Distillation
8-1
S-2
3-3
NOTES
7/95
Thermal Treatments
-------
NOTES
INCINERATION
• Incinerator &-
• Materials heated to combustion
• Residual solids dropped
• Combustion products released
S-4
INCINERATION
Advantages
Established technology
Destructien ef organics
Volume reduction
• Best demonstrated available
technology (BOAT)
s-s
INCINERATION
disadvantages
• Products of incomplete combustion (PICs)
• Toxic transformation by-products
• Not-in-my-back-yard (NIMBY) syndrome
• Emission control U
• Additional residuals treatment
WVCMA
S-8
Thermal Treatments
7/95
-------
NOTES
WASTE CHARACTERISTICS
• British thermal units (BTUs)
• Moisture acts as energy sink
• Inorganics >5% alkali metals
are corrosive
• Halogens >8% dry weight
are corrosive
COMBUSTION FACTORS
•Time
• Temperature
• Turbulence
• Oxygen
S-7
3-8
PRINCIPLE ORGANIC
HAZARDOUS CONSTITUENTS
POHCs are substances that scientific
studies have shown to be toxic or have
carcinogenic, mutagenic, or teratogenic
effects on humans or other life forms
40 CFR 204.342
S-9
7/95
Thermal Treatments
-------
NOTES
PERFORMANCE STANDARDS
Destruction Removal Efficiency (DRE)
DRE =
Win
X100
where W
n
Mass feed rate of POHC in the waste-
stream feed
WQUt= Mass emission rate of the POHC in the
stack gas prior to release into the
atmosphere
RCRA 99.99% most wastes/Specific wastes 99.9999%
~
40 CfP 164.343
3-10
AIR POLLUTION CONTROL
• Wet or dry scrubbers
- Neutralize acid gases
• Bag houses
- Remove particulate matter
• Permit limits
S-11
INCINERATOR DESIGNS
• Rotary kiln
• Infrared
S-12
Thermal Treatments
7/95
-------
ROTARY KILN INCINERATOR
Primary
combustion
chamber
Secondary
combustion
chamber
Flue
gas
scrubber
Stack
Waste
storage
hopper
U.S. EPA 1985
Ash removal
mechanism
Liquid
holding
tank
Legend
1 Influent waste 4 Secondary
2 Primary burner 5 Scrubber-baf^gr
3 Ash 6 Flue gas
S-13
NOTES
7/95
Thermal Treatments
-------
NOTES
INFRARED INCINERATION
Continuous conveyor belt furnace
1 Electric power
1 100 tons per day
us. EPA
8-14
SYSTEM COMPONENTS
Feed hoppers
Primary chamber
Secondary combustion chamber
Scrubber system
US. EPA 1880
S-15
PEAK OIL COMPANY
Tampa, Florida
Oiljrerefinery
- Contaminated sludges, soil, and
groundwater
- Polychlorinated biphenyls (PCBs)
and lead
US. EPA 1988
S-16
Thermal Treatments
7/95
-------
NOTES
WET-AIR OXIDATION
• Treatment for wastewaters
• Treatment targets
- Organics
- Oxidizable inorganics (cyanide)
• Range: 500 to 50,000 mg/L organics
• Up to 2% metals permitted
• Temperatures: 175to325°C
us. EPA
WET-AIR OXIDATION
• Oxidation temperature
• Residence time
• Excess oxygen concentration
• Oxidation pressure
• Catalyst
US. EPA 199)6
WET-AIR OXIDATION
PROCESS (cont.)
• Batch or continuous
U.S. EPA T9916
8-17
S-18
High-pressure liquid feed pump
Oxygen source
Reactor
Heat exchanger
Vapor-liquid separator
s-ie
7/95
Thermal Treatments
-------
CONTINUOUS WET-AIR OXIDATION SYSTEM
Air or
oxygen
Wastewater
influent
Pressurized
air or
oxygen
Heat
exchanger^
Pressurized
wastewater
AA/V
Waste heat
recovery
Steam
AA/V
Heat
exchanger
Reactor
Gas-liquid
phase
separator
(Liquid effluent
To atmosphere
Vent
gas
O o
Air
pollution
control
system
To additional treatment and/or disposal
S-20
NOTES
Thermal Treatments
7/95
-------
LOW-TEMPERATURE
DESORPTION
Used primarily for organic contaminated
soils
Usually rotary kiln
Soil temperature from 600 to 1000°F
Indirect-fired
S-21
LOW-TEMPERATURE
DESORPTION (cont.)
Inert carrier gas (oxygen <5%)
Maximum of 4% organics in soil
Vapors destroyed by catalytic oxidizer
Cocurrent or countercurrent flow
S-22
NOTES
7/95 9 Thermal Treatments
-------
TYPICAL LOW-TEMPERATURE DESORPTION
SYSTEM WITH OXIDIZER
Exhaust
stack
External heating
S-23
NOTES
Thermal Treatments
10
7/95
-------
LOW-TEMPERATURE DESORPTION
WITH CONDENSER
• Nondestructive
• Condenses and collects volatiles and
semivolatiles
• Condensate requires disposal
• More acceptable to public
• Clean soil can be returned to site
S-24
TYPICAL LOW-TEMPERATURE DESORPTION
SYSTEM WITH CONDENSERS
S-25
NOTES
7/95
11
Thermal Treatments
-------
NOTES
X*
LOW-TEMPERATURE DESORPTION
Advantages
• Less expensive than incineration
• Able to process 120-180 tons/day
• Will process volatile organics,
semivolatiles, PCBs, and volatile metals
(Hg and Pb)
S-28
'
LOW-TEMPERATURE DESORPTION
Disadvantages
• Net a destruction technology
• Process only works if the soil contains <10% total
erganics
• Technology only applicable to soil within the pH
range ®f 5-11
• Additional costs are incurred for carbon
regeneration and/or carbon disposal
• Process should not be used on soils with high
moisture contents 8-27
DISTILLATION
Recovery process
Purification of contaminated organics
Separation of organics by boiling point
differences
Heat provided by steam or hot oil
Vacuum may be used
S-28
Thermal Treatments
12
7/95
-------
DISTILLATION EQUIPMENT
• Columns - packed or tray
• Thin-film evaporators
• External or internal heat source
• Vapor condenser
• Fixed or portable
NOTES
S-20
DISTILLATION PRODUCTS
• Product recycled
• Two or more products may result
• Residues may be hazardous waste
• Fuels blending alternative
• Cost effective
S-30
7/95
13
Thermal Treatments
-------
REFERENCES
Code of Federal Regulations. 1992. 40 CFR Parts 260-299.
U.S. EPA. 1985. Handbook: Remedial Action at Waste Disposal Sites (Revised). EPA/625/6-
85/006. U.S. Environmental Protection Agency, Office of Emergency and Remedial Response,
Office of Research and Development, Hazardous Waste Engineering Laboratory, Cincinnati, OH.
U.S. EPA. 1989. Superfund Innovative Technology Evaluation: Applications Analysis Report.
Shirco Infrared Incinerator System. U.S. Environmental Protection Agency, Office of Research and
Development, Risk Reduction Engineering Laboratory, Cincinnati, OH.
U.S. EPA. 1990. Engineering Bulletin: Mobile/Transportable Incineration Treatment. EPA/540/2-
90/014. U.S. Environmental Protection Agency, Office of Research and Development, Risk
Reduction Engineering Laboratory, Cincinnati, OH.
U.S. EPA. 1991a. Superfund Engineering Issue: Issues Affecting the Applicability and Success
of Remedial/Removal Incineration Projects. EPA/540/2-91/004. U.S. Environmental Protection
Agency, Office of Research and Development, Office of Solid Waste and Emergency Response,
Washington, DC.
U.S. EPA. 1991b. Treatment Technologies. Second Edition. ISBN: 0-86587-263-5. U.S.
Environmental Protection Agency, Office of Solid Waste. Published by Government Institutes, Inc.,
Rockville, MD.
U.S. EPA. 1992. A Citizen's Guide to Air Sparging: Technology Fact Sheet. EPA/542/F-92/010.
U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response, Technology
Innovation Office, Washington, DC.
U.S. EPA. 1994. Engineering Bulletin: Thermal Desorption Treatment. EPA/540/S-94/501. U.S.
Environmental Protection Agency, Office of Emergency and Remedial Response, Washington, DC,
and Office of Research and Development, Cincinnati, Ohio.
Thermal Treatments 14 7/95
-------
6EPA
Purpose
Section 121(b) of the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA) mandates;
the Environmental Protection Agency (EPA) to select remedies
that "utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the maximum
extent practicable" and to prefer remedial actions in which
treatment "permanently and significantly reduces the volume,
toxicity, or mobility of hazardous substances, pollutants, and
contaminants as a principal element" The Engineering Bulletins
are a series of documents that summarize the latest information
available on selected treatment and site remediation
technologies and related issues. They provide summaries of
and references for the latest information to help remedial
project managers, on-scene coordinators, contractors, and
other site cleanup managers understand the type of data and
site characteristics needed to evaluate a technology for potential
applicability to their Superfund or other hazardous waste site.
Those documents that describe individual treatment
technologies focus on remedial investigation scoping needs.
Addenda will be issued periodically to update the original
bulletins.
Abstract
Incineration treats organic contaminants in solids and
liquids by subjecting them to temperatures typically greater
than 1000'F in the presence of oxygen, which causes the
volatilization, combustion, and destruction of these compounds.
This bulletin describes mobile/transportable incineration systems
that can be moved to and subsequently removed from Superfund
and other hazardous waste sites. It does not address other
thermal processes that operate at lower temperatures or those
that operate at very high temperatures, such as a plasma arc.
It is applicable to a wide range of organic wastes and is generally
not used in treating inorganics and metals. Mobile/transportable
incinerators exhibit essentially the same environmental
performance as their stationary counterparts. To date, 49 of the
95 records of decision (RODs) designating thermal remedies at
Superfund sites have selected onsite incineration as an integral
part of a preferred treatment alternative. There are 22
commercial-scale units in operation [5]*. This bulletin provides
information on the technology applicability, the types of residuals
resulting from the use of the technology, the latest performance
data, site requirements, the status of the technology, and
where to go for further information.
Technology Applicability
Mobile/transportable incineration has been shown to be
effective in treating soils, sediments, sludges, and liquids
containing primarily organic contaminants such as halogenated
and nonhalogenated volatiles and semivola tiles, polychlorinated
biphenyls (PCBs), pesticides, dioxins/furans, organic cyanides,
and organic corrosives. The process is applicable for the
thermal treatment of a wide range of specific Resource
Conservation and Recovery Act (RCRA) wastes and other
hazardous waste matrices that include pesticides and herbicides,
spent halogenated and nonhalogenated solvents, chlorinated
phenol and chlorinated benzene manufacturing wastes, wood
preservation and wastewater sludge, organic chemicals
production residues, pesticides production residues, explosives
manufacturing wastes, petroleum refining wastes, coke industry
wastes, and organic chemicals residues [1] [2] [4] [6 through 11]
[13].
Information on the physical and chemical characteristics of
the waste matrix is necessary to assess the matrix's impact on
waste preparation, handling, and feeding; incinerator type,
performance, size, and cost; air pollution control (APQ type
and size; and residue handling. Key physical parameters
include waste matrix physical characteristics (type of matrix,
physical form, handling properties, and particle size), moisture
content, and heating value. Key chemical parameters include
the type and concentration of organic compounds including
PCBs and dioxins, inorganics (metals), halogens, sulfur, and
phosphorous.
The effectiveness of mobile/transportable incineration on
general contaminant groups for various matrices is shown in
Table 1 [7, p. 9]. Examples of constituents within contaminant
groups are provided in Reference 7, "Technology Screening
Guide for Treatment of CERCLA Soils and Sludges." This table
* [reference number, page number]
-------
Table 1
Effectiveness of Incineration on General Contaminant
Groups for Soil, Sediment, Sludge, and Uquid
Contaminant Croups
.a
c3
Inorganic
|
1
Halogenated volatile*
Halogenated semivolatiles
Nonhalogenated volatiles
Nonhalogenated semivolatiles
PCBs
Pesticides (halogenated)
Dioxins/Furans
Organic cyanides
Organic corrosives
Volatile metals
Nonvolatile metals
Asbestos
Radioactive materials
Inorganic corrosives
Inorganic cyanides
Oxidizers
Reducers
Soil/
Sediment Sludge Uquid
T
T
Q
Q
Q
Q
Q
T
T
T
Q
Q
Q
Q
Q
T
T
T
V
T
Q
Q
Q
Q
Q
T
T
T
• Demonstrated Effectiveness: Successful treatability test at some scale
completed
T Potential Effectiveness: Expert opinion that technology will work
Q No Expeaed Effectiveness: Expert opinion that technology will not work
is based on current available information or professional
judgment when no information was available. The proven
effectiveness of the technology for a particular site or waste
does not ensure that it will be effective at all sites or that the
treatment efficiency achieved will be acceptable at other sites.
For the ratings used for this table, demonstrated effectiveness
means that, at some scale, treatability was tested to show that
the technology was effective for a particular contaminant and
matrix. The ratings of potential effectiveness or no expected
effectiveness are based upon expert judgment Where potential
effectiveness is indicated, the technology is believed capable of
successfully treating the contaminant group in a particular
matrix. When the technology is not applicable or will probably
not work for a particular combination of contaminant group
and matrix, a no-expected-effectiveness rating is given. Other
sources of general observations and average removal efficiencies
for different treatability groups are the Superfund LDR Guide
#6A, "Obtaining a Soil and Debris Treatability Variance for
Remedial Actions," (OSWER Directive 9347.3-06FS [13], and
Superfund LDR Guide #68, "Obtaining a Soil and Debris
Treatability Variance for Removal Actions," (OSWER Directive
9347.3-07FS [14].
Limitations
Toxic metals such as arsenic, lead, mercury, cadmium, and
chromium are not destroyed by combustion. As a result, some
will be present in the ash while others are volatilized and
released into the flue gas [1, pp. 3-6].
Alkali metals, such as sodium and potassium, can cause
severe refractory attack and form a sticky, low-melting-point
submicron particulate, which causes AFC problems. A low feed
stream concentration of sodium and potassium may be achieved
through feed stock blending [1, pp. 3-11].
When PCBs and dioxins are present, higher temperatures
and longer residence times may be required to destroy them to
levels necessary to meet regulatory criteria [7, p. 34].
Moisture/water content of waste materials can create the
need to co-incinerate these materials with higher BTU streams,
or to use auxiliary fuels.
The heating value (BTU content) of the feed material
affects feed capacity and fuel usage of the incinerator. In
general, as the heating value of the feed increases, the feed
capacity and fuel usage of the incinerator will decrease. Solid
materials with high calorific values also may cause transient
behaviors that further limit feed capacity [9, p. 4].
The matrix characteristics of the waste affect the
pretreatment required and the capacity of the incinerator and
can cause APC problems. Organic liquid wastes can be pumped
to and then atomized in the incinerator combustion chamber.
Aqueous liquids may be suitable for incineration if they contain
a substantial amount of organic matter. However, because of
the large energy demand for evaporation when treating large
volumes of aqueous liquids, pretreatment to dewater the waste
may be cost effective [1, pp. 3-14]. Also, if the organic content
is low, other methods of treatment may be more economical.
For the infrared incinerator, only solid and solid-like materials
within a specific size and moisture content range can be
processed because of the unique conveyor belt feed system
within the unit
Sandy soil is relatively easy to feed and generally requires
no special handling procedures. Clay, which may be in large
clumps, may require size reduction. Rocky soils usually require
screening to remove oversize stones and boulders. The solids
can then be fed by gravity, screw feeder, or ram-type feeder into
the incinerator. Some types of solid waste may also require
crushing, grinding, and/or shredding prior to incineration [1,
pp. 3-17].
The f orm and structure of the waste feed can cause periodic
jams in the feed and ash handling systems. Wooden pallets,
metal drum closure rings, drum shards, plastics, trash, clothing,
and mud can cause blockages if poorly prepared. Muddy soils
can stick to waste processing equipment and plug the feed
system [9, p. 8].
Engineering Bulletin:
-------
The particle size distribution of the ash generated from the
waste can affect the amount of paniculate carry-over from the
combustion chamber to the rest of the system [9, p. 16].
Incineration of halogens, such as fluorine and chlorine,
generates acid gases that can affect the capacity, the water
removal and replacement rates that control total dissolved
solids in the process water system, and the particulate emissions
[9, p. 12]. The solutions used to neutralize these acid gases add
to the cost of operating this technology.
Organic phosphorous compounds form phosphorous pent-
oxide, which attacks refractory material, causes slagging prob-
lems and APC problems. Slagging can be controlled by feed
blending or operating at lower temperatures [1, pp. 3-10].
Technology Description
Figure 1 is a schematic of the mobile/transportable
incineration process.
Waste preparation (1) includes excavation and/or moving
the waste to the site. Depending on the requirements of the
incinerator type for soils and solids, various equipment is used
to obtain the necessary feed size. Blending is sometimes
required to achieve a uniform feed size and moisture content or
to dilute troublesome components [1, pp. 3-19].
The waste feed mechanism (2), which varies with the type
of the incinerator, introduces the waste into the combustion
system. The feed mechanism sets the requirements for waste
preparation and is a potential source of problems in the actual
operation of incinerators if not carefully designed [1, pp. 3-19].
Different incinerator designs (3) use different mechanisms
to obtain the temperature at which the furnace is operated, the
time during which the combustible material is subject to that
temperature, and the turbulence required to ensure that all the
combustible material is exposed to oxygen to ensure complete
combustion. Three common types of incineration systems for
treating contaminated soils are rotary kiln, circulating fluidized
bed, and infrared.
The rotary kiln is a slightly inclined cylinder that rotates on
its horizontal axis. Waste is fed into the high end of the rotary
kiln and passes through the combustion chamber by gravity. A
secondary combustion chamber (afterburner) further destroys
unbumed organics in the flue gases [7, p. 40].
Figure 1
Mobile/Transportable Incineration Process
Vapor
Control
Waste
Storage
Waste
Treated
Emissions
Stack
Emissions
Waste
Preparation
(D
Water
Solids
Engineering Bulletin: Mobile/Transportable Incineration Treatment
-------
Circulating fluidized bed incinerators use high air velocity
to circulate and suspend the fuel/waste particles in a combustor
loop. Flue gas is separated from heavier particles in a solids
separation cyclone. Circulating fluidized beds do not require
an afterburner [7, p. 35].
Infrared processing systems use electrical resistance heating
elements or indirect fuel-fired radiant U-tubes to generate
thermal radiation [1, pp. 4-5]. Waste is fed into the combustion
chamber by a conveyor belt and exposed to the radiant heat.
Exhaust gases pass through a secondary combustion chamber.
Offgases from the incinerator are treated by the APC
equipment to remove particulates and capture and neutralize
acids (4). Rotary kilns and infrared processing systems may
require both external particulate control and acid gas scrubbing
systems. Circulating fluidized beds do not require scrubbing
systems because limestone can be added directly into the
combustor loop but may require a system to remove particulates
[1, pp. 4-11 ] [2, p. 32]. APC equipment that can be used include
venturi scrubbers, wet electrostatic precipitators, baghouses,
and packed scrubbers.
Process Residuals
Three major waste streams are generated by this technology:
solids from the incinerator and APC system, water from the APC
system, and emissions from the incinerator.
Ash and treated soil/solids from the incinerator combustion
chamber may be contaminated with heavy metals. APC system
solids, such as fly ash, may contain high concentrations of
volatile metals. If these residues fail required leachate toxicity
tests, they can be treated by a process such as stabilization/
solidification and disposed of onsite or in an approved landfill
[7, p. 126].
Liquid waste from the APC system may contain caustic,
high chlorides, volatile metals, trace organics, metal particulates,
and inorganic particulates. Treatment may require neutralization,
chemical precipitation, reverse osmosis, settling, evaporation,
filtration, or carbon adsorption before discharge [7, p. 127].
The flue gases from the incinerator are treated by APC
systems such as electrostatic precipitators or venturi scrubbers
before discharge through a stack.
Site Requirements
The site should be accessible by truck or rail and a graded/
gravel area is required for setup of the system. Concrete pads
may be required for some equipment (e.g., rotary kiln). For a
typical 5 tons per hour commercial-scale unit, 2 to 5 acres are
required for the overall system site including ancillary support
[10, p. 25].
Standard 440V three-phase electrical service is needed. A
continuous water supply must be available at the site. Auxiliary
fuel for feed BTU improvement may be required.
Contaminated soils or other waste materials are hazardous
and their handling requires that a site safety plan be developed
to provide for personnel protection and special handling
measures.
Various ancillary equipment may be required, such as
liquid/sludge transfer and feed pumps, ash collection and solids
handling equipment, personnel and maintenance facilities,
and process-generated waste treatment equipment. In addition,
a feed-materials staging area, a decontamination trailer, an ash
handling area, water treatment facilities, and a parking area
may be required [10, p. 24].
Proximity to a residential neighborhood will affect plant
noise requirements and may result in more stringent emissions
limitations on the incineration system.
Storage area and/or tanks for fuel, wastewater, and blending
of waste feed materials may be needed.
No specific onsite analytical capabilities are necessary on a
routine basis; however, depending on the site characteristics or
a specific Federal, State, or local requirement, some analytical
capability may be required.
Performance Data
More than any other technology, incineration is subject to
a series of technology-specific regulations, including the
following Federal requirements: the Clean Air Act 40 CFR 52.21
for air emissions; Toxic Substances Control Act (TSCA) 40 CFR
761.40 for PCB treatment and disposal; National Environmental
Policy Act 40 CFR 6; RCRA 40 CFR 261/262/264/270 for
hazardous waste generation, treatment performance, storage,
and disposal standards; National Pollutant Discharge Elimination
System 33 U.S.C. 1251 for discharge to surface waters; and the
Noise Control Act P.L 92-574. RCRA incineration standards
have been proposed that address metal emissions and products
of incomplete combustion. In addition. State requirements
must be met if they are more stringent than the Federal
requirements [1, p. 6-1].
All incineration operations conducted at CERCLA sites on
hazardous waste must comply with substantive and defined
Federal and State applicable or relevant and appropriate
requirements (ARARs) at the site. A substantial body of trial
bum results and other quality assured data exists to verify that
incinerator operations remove and destroy organic contaminants
from a variety of waste matrices to the parts per billion or even
the parts pertrillion level, while meeting stringent stack emission
and water discharge requirements. The demonstrated treatment
systems that will be discussed in the technology status section,
therefore, can meet all the performance standards defined by
the applicable Federal and State regulations on waste treatment,
air emissions, discharge of process waters, and residue ash
disposal [1, p. A-1] [4, p. 4] [10, p. 9].
RCRA Land Disposal Restrictions (LDRs) that require
treatment of wastes to best demonstrated available technology
(BOAT) levels prior to land disposal may sometimes be
determined to be ARARs for CERCLA response actions. The solid
Engineering Bulletin: Mobile/Transportable Incineration Treatment
-------
residuals from the incinerator may not meet required treatment
levels in all cases. In cases where residues do not meet BOAT
levels, mobile incineration still may be selected, in certain
situations, for use at the site if a treatability variance establishing
alternative treatment levels is obtained. EPA has made the
treatability variance process available in order to ensure that
LDRs do not unnecessarily restrict the use of alternative and
innovative treatment technologies. Treatability variances may
be justified for handling complex soil and debris matrices. The
following guides describe when and how to seek a treatability
variance for soil and debris: Superfund LDR Guide #6A,
"Obtaining a Soil and Debris Treatability Variance for Remedial
Actions," (OSWER Directive 9347.3-06FS) [13] and Superfund
LDR Guide #66, "Obtaining a Soil and Debris Treatability
Variance for Removal Actions," (OSWER Directive 9347.3-
07FS) [14].
Technology Status
To date, 49 of the 95 RODs designating thermal remedies
at Superfund sites have selected onsite incineration as an
integral part of a preferred treatment alternative.
Table 2 lists the site experience of the various mobile/
transportable incinerator systems. It includes information on
the incinerator type/size, the site size, location, and contaminant
source or waste type treated [5] [3, p. 80] [8, p. 74].
The cost of incineration includes fixed and operational
costs. Fixed costs include site preparation, permitting, and
mobilization/demobilization. Operational costs such as labor,
utilities, and fuel are dependent on the type of waste treated
and the size of the site. Figure 2 gives an estimate of the total
cost for incinerator systems based on site size [12, pp. 1-3].
Superfund sites contaminated with only volatile organic
compounds can have even lower costs for thermal treatment
then the costs shown in Figure 2.
EPA Contact
Technology-specific questions regarding mobile/
transportable incineration may be directed to Donald A.
Oberacker, U.S. EPA Risk Reduction Engineering Laboratory, 26
West Martin Luther King Drive, Cincinnati, Ohio 45268,
telephone: FTS 684-7510 or (513) 569-7510.
Table 2.
Technology Status
Tieutineiil
System/
Vendor
Rotary Kiln
Ensco
Rotary Kiln
IT
Rotary Kiln
Vesta
Thermal
Capacity
(MMBTU/Hr)
35
100
56
8
12
Experience
Site, Location
Sydney Mines, Valrico, FL4
Lenz Oil NPL Site, Lemont, IL4
Naval Construction Battalion
Center (NCBQ, Gulfport, MS
Union Carbide, Seadrift, TX*
Smithiville, Canada*
Bridgeport Rental, Bridgeport, NJ*4
Comhusker Army Ammunition Plant
(CAAP), Grand Island, NE4
Louisiana Army Ammunition Plant
(LAAP), Shreveport, LA*4
Motco, Texas City, TX*4
Fairway Six Site, Aberdeen, NC
Fort A.P. Hill, Bowling Green, VA
Nyanza/Nyacol Site, Ashland, MA4
Southern Crop Services Site
Delray Beach, FL
American Crossarm & Conduit Site
Chehalis, WA4
Rocky Boy, Havre, MT*
Waste Volume
(tons)
10,000
26,000
22,000
N/A
7,000
100,000
45,000
100,000
80,000
50
200
1,000
1,500
900
1,800
Contaminant Source or
Waste Type
Waste oil
Hydrocarbon - sludge/solid/liquid
Dioxin/soil
Chemical manufacturing
PCB transformer leaks
Used oil recycling
Munitions plant redwater pits
Munitions plant redwater lagoon
Styrene tar disposal pits
Pesticide dump
Army base
Dye manufacturing
Crop dusting operation
Wood treatment
Wood treatment
NA - Not available * Contracted, others completed 4 Superfund Site
[Source: References 3, 5, 8]
Engineering Bulletin: Mobile/Transportable Incineration Treatment
-------
Table 2
Technology Status (Continued)
Treatment
System/
Vendor
Rotary Kiln
Weston
Rotary Kiln
AET
Rotary Kiln
Boliden
Rotary Kiln
Harmon
Rotary Kiln
Bell
Rotary Kiln
Kimmiru
Rotary Kiln
USEPA
Rotary Kiln
Vertac
Shirco Infrared
Hazteeh
Shirco Infrared
CDCEngr.
Shirco Infrared
OH Materials
Shirco Infrared
U.5. Waste
Crculating Bed
Combustor
Ogden
Thermal
Capacity
(MMBTU/Hr)
35
20
40
82
30
100
10
35
30
NA
30
12
10
10
Experience
Site, Location
Lauder Salvage, Beardstown, IL
Paxton Ave., Chicago, IL*
Valdez, AK
Oak Creek, Wl
Prentis Creosote & Forest Products
Prentis, MS
Bog Creek, Howell Township, NJ"
Bell Lumber&Pole,
New Brighton, MN4
Lasalle, IL*4
Denney Farm, MO
Vertac, Jacksonville, AR*4
Peak Oil, Tampa, FL4
Lasalle, IL4
Rubicon, Ceismar, LA*
Florida Steel, Indiantown, FL4
Twin City AAP, New Brighton, MN
Coosebay, Canada
Gas Station Site, Cocoa, FL
Private Site, San Bemadino, CA
Arco Swanson River Field
Kenai, AK*
Stockton, CA*
Waste Volume
(tons)
8,500
16,000
NA
50,000
9,200
22,500
21,000
69,000
6,250
6,500
7,000
30,000
52,000
18,000
2,000
4,000
1,000
5,400
80,000
16,000
Contaminant Source or
Waste Type
Metal scrap salvage
Waste lagoon
Crude oil spill
Dye manufacturing
Creosote/soil
Organics
Wood treatment
PCB capacitor manufacturing
Dioxin Soils
Chemical manufacturing
Used oil recycling, PCBs/Lead
Transformer reconditioning
Chemical manufacturing
Steel mill used oils
Munitions plant
PCBs
Petroleum tank leak
Hydrocarbons
Oil pipeline compressor oil
Underground tank oil leak
NA - Not available * Contracted, others completed "Superfund Site
[Source: References 3,5,8]
Engineering Bulletin: Mobile/Transportable Incineration Treatment
-------
Rgure2
Effect of Site Size on Incineration Costs
Very Small Small Medium Large
<5,000 5,000-15,000 15,000-30,000 >30,000
Source The Hazardous Waste Consultant [12, pp. 1-3]
Site Size-Tons
REFERENCES
1. High Temperature Thermal Treatment for CERCLA
Waste: Evaluation and Selection of On-site and Off-site
Systems. EPA/540/X-88/006, U.S. Environmental
Protection Agency Office of Solid Waste and
Emergency Response, December 1988.
2. Gupta, C., A. Sherman, and A. Gangadharan,
Hazardous Waste Incineration: The Process and the
Regulatory/Institutional Hurdles, Foster Wheeler
Enviresponse, Inc., Livingston, N]., (no date).
3. Cudahy, J., and A. Eicher. Thermal Remediation
Industry, Markets, Technology, Companies, Pollution
Engineering, 1989.
4. Stumbar, j., et al. EPA Mobile Incineration
Modifications, Testing and Operations, February 1986
to June 1989. EPA/600/2-90/042, U.S. Environmental
Protection Agency, 1990.
5. Gudahy, J., and W. Troxler. Thermal Remediation
Industry Update II, Focus Environmental, Inc. Knoxville,
TN, 1990.
6. Experience in Incineration Applicable to Superfund Site
Remediation. EPA/625/9-88/008, U.S. Environmental
Protection Agency Risk Reduction Engineering
Laboratory and Center for Environmental Research
Information, 1988.
7. Technology Screening Guide for Treatment of CERCLA
Soils and Sludges. EPA/540/2-88/004, U.S.
Environmental Protection Agency, 1988.
8. Johnson, N., and M. Cosmos. Thermal Treatment
Technologies for Haz Waste Remediation, Pollution
Engineering, 1989.
9. Stumbar, j., et al. Effect of Feed Characteristics on the
Performance of Environmental Protection Agency's
Mobile Incineration System. In Proceedings of the
Fifteenth Annual Research Symposium, Remedial
Action, Treatment and Disposal of Hazardous Wastes.
EPA/600/9-90/006,1990.
10. Shirco Infrared Incineration System, Applications
Analysis Report EPA/540/A5-89/010, U.S.
Environmental Protection Agency, 1989.
11. Mobile Treatment Technologies for Superfund Wastes.
EPA 540/2-86/003(f), U.S. Environmental Protection
Agency Office of Solid Waste and Emergency Response,
1986.
12. McCoy and Associates, Inc., The Hazardous Waste
Consultant, Volume 7, Issue 3,1989.
13. Superfund LDR Guide #6A: Obtaining a Soil and
Debris Treatability Variance for Remedial Actions.
OSWER Directive 9347.3-06FS, U.S. Environmental
Protection Agency, 1989.
14. Superfund LDR Guide #6B: Obtaining a Soil and Debris
Treatability Variance for Removal Actions. OSWER
Directive 9347.3-07FS, U.S. Environmental Protection
Agency, 1989.
Engineering Bulletin: Mobile/Transportable Incineration Treatment
-------
Additional Reference:
Oppelt, E.T. Incineration of Hazardous Waste-A Crtitical
Review. j. Air Poll. Cont. Assn. 37(5):5S8-586,1987.
United States Center for Environmental Research BULK RATE
Environmental Protection Information POSTAGE & FEES PAID
Agency Cincinnati, OH 45268 EPA
PERMIT No. C-35
Official Business
Penalty for Private Use $300
-------
United States
Environmental Protection
Agency
Off ice of
Solid Waste and
Emergency Response
EPA/542/F-92/006
March 1992
&EPA
A Citizen's Guide to
Thermal Desorption
Technology Innovation Office
/Technology Fact Sheet
Pag*
CONTENTS
What Is Thermal
Desorption?
How Does Thermal
Desorption Work?
Why Consider Thermal
Desorption? 3
Will It Work At Every
SKe? 3
Where Is Thermal
Desorption Being
Selected? 3
For More Information
What Is Thermal
Desorption?
Thermal desorption is an innovative
treatment technology that treats soils
contaminated with hazardous wastes by
heating the soil at relatively low
temperatures (200-1000°F) so that
contaminants with low boiling points
will vaporize (turn into gas) and,
consequently, separate from the soil.
(The other soil contaminants, if any, are
treated by other methods.) The
vaporized contaminants are collected
and treated, typically by an air
emissions treatment system.
Thermal desorption is a different
treatment process than incineration.
Thermal desorption uses heat to
physically separate the contaminants
from the soil, which then require further
treatment Incineration uses heat to
actually destroy the contaminants.
How Does Thermal
Desorption Work?
Thermal desorption makes use of either
in situ or ex situ processes. In situ - in
place — treats soils without excavating
them. Ex situ treats excavated soils.
There are three steps in thermal
desorption: 1) heating the soil to
vaporize the contaminants; 2) treating
the vaporized contaminants; and 3)
testing the treated soil. There are four
different methods for heating the soil to
vaporize the contaminants:
• In situ steam extraction
• Direct heating
Indirect heating
• Oxygen free heating
See Figure 1 on page 2 for an
illustration of in situ steam extraction.
Figure 2 on page 2 shows the processes
that require excavation: direct heating,
indirect heating, and oxygen free
heating.
Thermal Desorption Profile
Heats soil at relatively low temperatures to vaporize contaminants and remove them.
Is most effective at treating volatile organic compounds, semrvolatlle organic compounds and other
organic contaminants, such as porychtorlnated blphenyls (PCBs), and polysromatlc hydrocarbons
(PAHsj.
Offers a variety of heating methods for vaporizing the organic contaminants from the soil. These heating
methods Include transportable and In situ technologies.
Produced by the
Supcxfijnd Pngrun
Printed on Recycled Paper
-------
Figure 1
In Situ Steam Extraction
Further TiMDiwm
orDfcpoul
A variety of factors determine which heating method will be
used, including soil type and amount, contaminant type and
amount, and cost Each of the four heating methods are
briefly described below:
In situ (in place) steam extraction (Figure 1, above) - the
soil is kept in place, and hot steam is pumped through the
ground. The volatile contaminants vaporize and are
collected in a vacuum. A disadvantage to this heating
method is that a limited area of soil is treated at one time.
Contaminants are, therefore, removed at a slower rate.
Direct heating (Figure 2, below) - the soil is excavated and
put into a treatment vessel. The treatment vessel is heated
and the heat is transferred to the soil. As the contaminants
become heated they vaporize. The advantage of this heating
method is that it is simple and cost effective to set up.
Indirect heating (Figure 2, below) - the soil is excavated
and put into a treatment vessel. A burner is transported to
the site, which heats an air source. The heated air is
pumped into the treatment vessel by a blower. The air heats
the soil, which causes the contaminants to vaporize. This
heating method requires more fuel because some heat is lost
during transfer.
Figure 2
Three Ex Situ Thermal Desorptlon Methods
-------
Oxygen free (Figure 2, page 2) • the soil is placed in a
treatment vessel which has no oxygen and which is sealed
and filled with nitrogen to avoid any contact between the
soil and oxygen. The outside of the vessel is heated, and the
contaminants vaporize.
Once vaporized, the contaminants can be treated in the same
manner regardless of the heating method. The vaporized
contaminants are either 1) cooled and condensed into a
liquid, which is then placed in drums for treatment or
disposal; or 2) trapped in carbon filters which are then
treated or disposed of; or 3) burned in an afterburner. All
disposals must meet Federal, State, and local standards. The
selection of the vapor treatment system depends on the
concentration of the contaminants, cleanup standards, and
various economic and engineering considerations.
The performance of thermal desorption is typically
measured by comparing the contaminant levels in treated
soils with those of untreated soils. With the ex situ
processes, if the treated soil is nonhazardous, it is
redeposited on-site or taken elsewhere as backfill If,
however, the soil requires further treatment (for example,
there are additional contaminants that do not respond to this
process), it may be treated with another technology or
transported off-site for disposal.
Why Consider Thermal Desorption?
Thermal desorption can effectively reduce hazards to both
people and the environment Thermal desorption is most
successful in treating soils, sediments, and sludges that are
contaminated with volatile organic compounds, semivoladle
organic compounds, polychlorinated biphenyls (PCBs), and
some polyaromatic hydrocarbons (PAHs). The equipment
available is capable of treating up to 10 tons of
contaminated soil per hour. Finally, the low temperatures
require less fuel than other treatment methods.
Will It Work At Every Site?
Thermal desorption does not work well on all types of soil
If the soil is wet, water will vaporize along with the
contaminants. Because of the additional substance (water)
being vaporized, more fuel is required to vaporize all the
contaminants in the wet soil. Soils with high silt and clay
content are also more difficult to treat with thermal
desorption. When heated, silt and clay emit dust, which can
disrupt the air emission equipment used to treat the
vaporized contaminants. In addition, tightly packed soil
often does not permit the heat to make contact with all of
the contaminants. It is, therefore, difficult for them to
vaporize. Finally, thermal desorption has limited
effectiveness in treating contaminants such as heavy metals,
since they do not separate easily from the soil, and strong
acids, since they can corrode the treatment equipment
Where Is Thermal Desorption Being
Selected?
Thermal desorption has been selected as a treatment method
at numerous Superfund sites. For example, thermal
desorption was used at the Cannon Engineering Corporation
site in Plymouth, Massachusetts to treat soil contaminated
with volatile organic compounds and semivolatile organic
compounds. Thermal desorption effectively treated 11,330
tons of contaminated soil at the site. The process began in
May 1990 and was completed five months later in October
1990. With this technology, cleanup goals for the site were
met and exceeded. In addition, the property was restored so
that once again, it can be put to commercial or industrial
use. Table 1 on the following page lists some additional
Superfund sites where thermal desorption has been selected
or used, their locations, and the types of facilities requiring
treatment
What Is An Innovative
Treatment Technology?
Treatmenttechnologies are processes
applied to the treatment of hazardous
waste or contaminated materials to
permanently alter their condition
through chemical, biological, or
physical means. Technologies that
have been tested, selected or used for
treatment of hazardous waste or
contaminated materials but lack well-
documented cost and performance
data under a variety of operating
conditions are called Innovative
treatment technologies.
-------
Table 1
Superfund Sites Where Thermal Desorptlon Has Been Used or Selected
Site
Cannon Engineering
McKin
Ottati and Goss
RE-Sotve
American Thermostat
University of Minnesota
Martin Marietta
Caldwell Trucking
Claremont Polychemical
Fulton Terminals
Marathon Battery
Metaltec/Aerosystems
Reich Farms
Samey Farm
Waldick Aerospace Devices
Wamchem
Outboard Marine/
Waukegan Harbor
Location
Massachusetts
Maine
New Hampshire
Massachusetts
New York
Minnesota
Goto rack)
New Jersey
New York
New York
New York
New Jersey
New Jersey
New York
New Jersey
South Carolina
Illinois
Types of Facilities*
Chemical waste handling, storage, and incineration
Waste storage, transfer, disposal
Drum reconditioning
Chemical reclamation
Industrial manufacturing of thermostats
University wastes (PCBs)
Aerospace equipment manufacturer
Unpermitted septic waste
Chemical
Former waste tank farm
Former battery manufacturer
Metal manufacturing
Uncontrolled waste disposal
Industrial and municipal landfill
Manufacturing and electroplating of plane parts
Former dye manufacturing plant
Marine products manufacturing
'All waste types and site conditions are not similar. Each site must be individually investigated and tested. Engineer-
ing and scientific judgment must be used to determine if a technology is appropriate for a site.
For More Information
EPA prepared this fact sheet to provide basic Information on thermal desorptlon. Additional technical
reports listed betow may be obtained by calling (513) 569-7562 or writing to:
Center for Environmental Research Information
26 West Martin Luther King Drive
Cincinnati, OH 45268
There may be a charge for these documents,
U.S. Environmental Protection Agency, 1990. In Situ Steam/Hot Air Stripping, Toxic Treatment, Inc.,
EPA/54Q/M5-90/003.
• U.S. Environmental Protection Agency, 1990. Inventory of Treatablllty Study Vendors, Volume 1,
EPA/540/2-90/003a;
• U.S. Environmental Protection Agency, 1990. Second Forum on Innovative Treatment Technologies,
Domestic and International, Philadelphia, PA, May 15-17,1990, EPA/540/2-90/006 (Abstracts) or EPA/
540/2-90/010 (Technical Papers).
U.S. Environmental Protection Agency, 1991. Engineering Bulletin: Thermal Desorptlon Treatment,:
EPA/540/2-91/008; ' ' ' ".'.. ' ' •:.:'—";.-:-:":-:V,: V.'" '
NOTICE: This laa sheet is intended solely as general guidance and information. It is not intended, nor can It be relied upon. U create any rights enforceable by any
party in litigation with the United States. The Agency also resenes the right IB change this guidance at any time without pubic notice.
•US. Qowmmnt Printing OffcK 1902 — 848-06080000
-------
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Purpose
Section 121 (b) of the Comprehensive Environmental Re-
sponse, Compensation, and Liability Act (CERCLA) mandates
the Environmental Protection Agency (EPA) to select remedies
that "utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the maxi-
mum extent practicable" and to prefer remedial actions in
which treatment "permanently and significantly reduces the
volume, toxicity, or mobility of hazardous substances, pollut-
ants and contaminants as a principal element." The Engineer-
ing Bulletins are a series of documents that summarize the latest
information available on selected treatment and site remedia-
tion technologies and related issues. They provide summaries
of and references for the latest information to help remedial
project managers, on-scene coordinators, contractors, and
other site cleanup managers understand the type of data and
site characteristics needed to evaluate a technology for poten-
tial applicability to their Superfund or other hazardous waste
site. Those documents that describe individual treatment tech-
nologies focus on remedial investigation scoping needs. This
document is an update of the original bulletin published in May
1991 [!].•
Abstract
Thermal desorption is an ex situ means to physically
separate volatile and some semivolatile contaminants from soil,
sediments, sludges, and filter cakes by heating them at temper-
atures high enough to volatilize the organic contaminants. For
wastes containing up to 10 percent organics or less, thermal
desorption can be used in conjunction with offgas treatment
for site remediation. It also may find applications in conjunc-
tion with other technologies at a site.
Thermal desorption is applicable to organic wastes and
generally is not used for treating metals and other inorganics.
The technology thermally heats contaminated media, gener-
ally between 300 to 1,000°F, thus driving off the water, volatile
contaminants, and some semivolatile contaminants from the
contaminated solid stream and transferring them to a gas
stream. The organics in the contaminated gas stream are then
treated by being burned in an afterburner, condensed in a
single- or multi-stage condenser, or captured by carbon ad-
sorption beds.
The use of this well-established technology is a site-specific
determination. Thermal desorption technologies are the se-
lected remedies at 31 Superfund sites [2]. Geophysical investi-
gations and other engineering studies need to be performed to
identify the appropriate measure or combination of measures
to be implemented based on the site conditions and constitu-
ents of concern at the site. Site-specific treatability studies may
be necessary to establish the applicability and project the likely
performance of a thermal desorption system. The EPA contact
indicated at the end of this bulletin can assist in the identifica-
tion of other contacts and sources of information necessary for
such treatability studies.
This bulletin discusses various aspects of the thermal
desorption technology including applicability, limitations of its
use, residuals produced, performance data, site requirements,
status of the technology, and sources of further information.
Technology Applicability
Thermal desorption has been proven effective in treating
organic-contaminated soils, sediments, sludges, and various
filter cakes. Chemical contaminants for which bench-scale
through full-scale treatment data exist include primarily volatile
organic compounds (VOCs), semivolatile organic compounds
(SVOCs), polychlorinated biphenyls (PCBs), pentachloro-
phenols (PCPs), pesticides, and herbicides [1][3][4][5][6][7].
The technology is not effective in separating inorganics from
the contaminated medium.
Extremely volatile metals may be removed by higher
temperature thermal desorption systems. However, the tem-
perature of the medium produced by the process generally
does not oxidize the metals present in the contaminated
medium [8, p. 85]. The presence of chlorine in the waste can
affect the volatilization of some metals, such as lead. Generally,
as the chlorine content increases, so will the likelihood of metal
volatilization [9].
• [reference number, page number]
Printed on Recycled Paper
-------
The technology is also applicable for the separation
of organtcs from refinery wastes, coal tar wastes, wood-treating
wastes, creosote-contaminated soils, hydrocarbon-
contaminated soils, mixed (radioactive and hazardous) wastes,
synthetic rubber processing wastes, and paint wastes [4][10,
Table 1
RCRA Codes for Wastes Treated
by Thermal Desorption
Performance data presented in this bulletin should not be
considered directly applicable to other Superfund sites. A
number of variables, such as concentration and distribution of
contaminants, soil particle size, and moisture content, can all
affect system performance. A thorough characterization of the
site and well-designed and conducted treatability studies of all
potential treatment technologies are highly recommended.
Table 1 lists the codes for the specific Resource Conserva-
tion and Recovery Act (RCRA) wastes that have been treated by
this technology [4][10, p.7][11]. The indicated codes were
derived from vendor data where the objective was to determine
thermal desorption effectiveness for these specific industrial
wastes.
The effectiveness of thermal desorption on general con-
taminant groups for various matrices is shown in Table 2.
Examples of constituents within contaminant groups are pro-
vided in Technology Screening Guide For Treatment of CERCLA
Soils and Sludges" [8, p. 10]. This table has been updated and
is based on the current available information or professional
judgment where no information was available. The proven
effectiveness of the technology for a particular site or waste
does not ensure that it will be effective at all sites or that the
treatment efficiencies achieved will be acceptable at other sites.
For the ratings used for this table, demonstrated effectiveness
means that, at some scale, treatability was tested to show the
technology was effective for that particular contaminant and
medium. The ratings of potential effectiveness or no expected
effectiveness are both based upon expert judgment. Where
potential effectiveness is indicated, the technology is believed
capable of successfully treating the contaminant group in a
particular medium. When the technology is not applicable or
will likely not work for a particular combination of contaminant
group and medium, a no expected effectiveness rating is given.
Another source of general observations and average re-
moval efficiencies for different treatability groups is contained
in the Superfund Land Disposal Restrictions (LOR) Guide #6A,
"Obtaining a Soil and Debris Treatability Variance for Remedial
Actions," (OSWER Directive 9347.3-06FS, September 1990)
[12] and Superfund LDR Guide #6B, "Obtaining a Soil and
Debris Treatability Variance for Removal Actions," (OSWER
Directive 9347.3-06BFS. September 1990) [1 3].
A further source of information is the U.S. EPA's Risk
Reduction Engineering Laboratory Treatability Database (ac-
cessible via ATTIC).
Technology Limitations
Inorganic constituents or metals that are not particularly
volatile will unlikely be effectively removed by thermal desorp-
tion. If there is a need to remove a portion of them, a vendor
Wood Treating Wastes K001
Dissolved Air Flotation . K048
Stop Oil Emulsion Solids K049
Heat Exchanger Bundles Cleaning Sludge KOSO
American Petroleum Institute (API)
Separator Sludge K051
Tank Bottoms (leaded) K052
Table 2
Effectiveness of Thermal Desorption on General
Contaminant Groups for Soil, Sludge, Sediments,
and Filter Cakes
Cofltomtonf Croups
M
S
g
M
|
|
$
<
8
Hatogenated voUtltes
Hatogenated semivolatiles
Nonhalogenated volatile*
Nonhalogenated semtvolatUes
PCBs
Pesticides
Dtoxlns/Furans
Organic cyanides
Organic corrosives
Volatile metals
Nonvolatile meutj
Asbestos
Radioactive materials
Inorganic corrosives
Inorganic cyanides
Oxidizers
Reducers
Jtdf- FUttr
Je* Oudgt mtntt Cotes
Q
•
Q
Q
a
a
a
a
Q
T
•
T
T
T
T
T
T
0
T
a
a
a
Q
Q
a
Q
T
T
T
T
•
T
T
T
a
T
0
a
a
a
Q
a
a
Q
T
a
a
Q
Q
a
a
a
• Demonstrated Effectfveness: Successful treaubUlty test at some KJte
completed
T Potential Effectiveness: Expert opinion that technology wil wort
Q No Expected Effectiveness: Expert opinion trial technology wM not
work
process with a very high bed temperature is recommended due
to the fact that a higher bed temperature will generally result
in a greater volatilization of contaminants. If chlorine or
another chlorinated compound is present, some volatilization
of inorganic constituents in the waste may also occur [14, p.8].
The contaminated medium must contain at least 20 per-
cent solids to facilitate placement of the waste material into the
desorption equipment [3, p. 9]. Some systems specify a
minimum of 30 percent solids [15, p. 6].
Engineering Bulletin: Thermal Desorption Treatment
-------
As the medium is heated and passes through the kiln or
desorber, energy is consumed in heating moisture contained in
the contaminated soil. A very high moisture content may result
in low contaminant volatilization, a need to recycle the soil
through the desorber, or a need to dewater the material prior
to treatment to reduce the energy required to volatilize the
water.
Material handling of soils that are tightly aggregated or
largely clay can result in poor processing performance due to
caking. Rock fragments or particles greater than 1 to 2 inches
may have to be prepared by being crushed, screened, or
shredded in order to meet the minimum treatment size.
However, one advantage to soil preparation is that the con-
taminated medium is mixed and exhibits a more uniform
moisture and BTU content
If a high fraction of fine silt or clay exists in the matrix,
fugitive dusts will be generated [8, p. 83], and a greater dust
loading wiH be placed on the downstream air pollution control
equipment [IS, p. 6].
The treated medium will typically contain less than 1
percent moisture. Dust can easily form in the transfer of the
treated medium from the desorption unit, but can be mitigated
by water sprays. Normally, clean water from air pollution
control devices can be used for this purpose. Some type of
enclosure may be required to control fugitive dust if water
sprays are not effective.
Although volatile and semivolatile organics are the primary
target of the thermal desorption technology, the total organic
loading is limited by some systems to 10 percent or less [16, p.
11-30]. As in most systems that use a reactor or other equipment
to process wastes, a medium exhibiting a very high pH (greater
than 11) or very low pH (less than 5) may corrode the system
components [8, p. 85].
There is evidence with some system configurations that
polymers may foul or plug heat transfer surfaces [3, p. 9].
Laboratory/field tests of thermal desorption systems have docu-
mented the deposition of insoluble brown tars (presumably
phenolic tars) on internal system components [1 6, p. 76],
Caution should be taken regarding the disposition of the
treated material, since treatment processes may alter the
physical properties of the material. For example, this material
could be susceptible to such destabilizing forces as liquefaction,
where pore pressures are able to weaken the material on sloped
areas or places where materials must support a load (i.e., roads
for vehicles, subsurfaces of structures, etc.). To achieve or
increase the required stability of the treated material, it may
have to be mixed with other stabilizing materials or compacted
in multiple lifts. A thorough geotechnical evaluation of the
treated product would first be required [14, p.8].
There is also a possibility, that during the cleanup process
at a particular site dioxins and furans may form and be released
from the exhaust stack into the environment The possibility of
this occurring should be determined on a case-by-case basis.
Technology Description
Thermal desorption is a process that uses either indirect or
direct heat exchange to heat organic contaminants to a tem-
perature high enough to volatilize and separate them from a
contaminated solid medium. Air, combustion gas, or an inert
gas is used as the transfer medium for the vaporized compo-
nents. Thermal desorption systems are physical separation
processes that transfer contaminants from one phase to an-
other. They are not designed to provide high levels of organic
destruction, although the higher temperatures of some sys-
tems will result in localized oxidation or pyrolysis. Thermal
desorption is not incineration, since the destruction of organic
contaminants is not the desired result The bed temperatures
achieved and residence times used by thermal desorption
systems will volatilize selected contaminants, but usually not
oxidize or destroy them. System performance is usually mea-
sured by the comparison of untreated solid contaminant levels
with those of the processed solids. The contaminated medium
is typically heated to 300 to 1,000% based on the thermal
desorption system selected.
Figure 1 is a general schematic of the thermal desorption
process.
Material handling (1) requires excavation of the contam-
inated solids or delivery of filter cake to the system. Typically,
large objects (greater than 2 inches in diameter) are screened,
crushed, or shredded and, if still too large, rejected. The
material to be treated is then delivered by gravity to the
desorber inlet or conveyed by augers to a feed hopper [6, p. 1 ].
Desorption (2) of contaminants can be effected by use of
a rotary dryer, thermal screw, vapor extractor (fluidized bed),
or distillation chamber [IS].
As the waste is heated, the contaminants vaporize, and are
then transferred to the gas stream. An inert gas, such as
nitrogen, may be injected as a sweep stream to prevent
contaminant combustion and to aid in vaporizing and remov-
ing the contaminants [4][10, p. 1 ]. Other systems simply direct
the hot gas stream from the desorption unit [3, p. 5][5].
The actual bed temperature and residence time are pri-
mary factors affecting performance in the desorption stage.
These factors are controlled in the desorption unit by using a
series of increasing temperature zones [10, p. 1], multiple
passes of the medium through the desorber where the operat-
ing temperature is sequentially increased, separate compart-
ments where the heat transfer fluid temperature is higher, or
sequential processing into higher temperature zones [17][18].
Heat transfer fluids used include hot combustion gases, hot oil,
steam, and molten salts.
Offgas from desorption is typically processed (3) to re-
move particulates that were entrained into the gas stream
during the desorption step. Volatiles in the offgas may be
burned in an afterburner, collected on activated carbon, or
recovered in condensation equipment. The selection of the gas
treatment system will depend on the concentrations of the
Engineering Bulletin: Thermal Desorption Treatment
-------
:iean Oftgas
Excavation
Material
Handling
(1)
I
Paniculate
Removal/Gas
Treatment System
(3)
Spent Carbon
Concentrated
Contaminants
^-Water
Oversized Rejects
Rgunt 1
Schematic Diagram of Thermal Desorptlon
~
contaminants, air emission standards, and the economics of
the offgas treatment system(s) employed. Some methods
commonly used to remove the particulates from the gas stream
are cyclones, wet scrubbers, and baghouses. In a cyclone,
particulates are removed by centrifugal force. In a wet scrub-
ber, the contaminated gas stream passes upward through
water sprays, causing the particulates to be washed out at the
bottom of the scrubber. In a baghouse, particulates are caught
by bags and discharged out of the system.
Process Residuals
Operation of thermal desorption systems may create up to
six process residual streams: treated medium; oversized me-
dium and debris rejects; condensed contaminants and water;
spent aqueous and vapor phase activated carbon; paniculate
dust; and clean offgas. Treated medium, debris, and oversized
rejects may be suitable for return onsite.
The vaporized organic contaminants can be captured by
condensation or passing the offgas through a carbon adsorp-
tion bed or other treatment system. Organic compounds may
also be destroyed by using an offgas combustion chamber or
a catalytic oxidation unit [14, p.5].
When offgas is condensed, the resulting water stream may
contain significant contamination depending on the boiling
points and solubility of the contaminants and may require
further treatment (i.e., carbon adsorption). If the condensed
water is relatively clean, it may be used to suppress the dust
from the treated medium. If carbon adsorption is used to
remove contaminants from the offgas or condensed water,
spent carbon will be generated, and is either returned to the
supplier for reactivation/incineration or regenerated onsite [14,
P-5].
Offgas from a thermal desorption unit will contain partic-
ulates from the medium, vaporized organic contaminants, and
water vapor. Particulates are removed by conventional equip-
ment such as cyclones, wet scrubbers, and baghouses. Collect-
ed particulates may be recycled through the thermal desorp-
tion unit or blended with the treated medium, depending on
the concentration of organic contaminants present on the
particulates. Very small particles (<1 micron) can cause a visible
plume from the stack [14, p.5].
When offgas is destroyed by a combustion process, com-
pliance with incineration emission standards may be required.
Obtaining the necessary permits and demonstrating compli-
ance may be advantageous, however, since the incineration
process would not leave residuals requiring further treatment
IK p.5].
Site Requirements
Thermal desorption systems typically are transported on
specifically adapted flatbed semitrailers. Most systems consist
of three components (desorber, paniculate control, and gas
treatment). Space requirements onsite are typically less than
150 feet by 150 feet, exclusive of materials handling and
decontamination areas.
Standard 440V, three-phase electrical service is needed.
Water must be available at the site. The quantity of water
needed is vendor- and site-specific.
Treatment of contaminated soils or other waste materials
require that a site safety plan be developed to provide for
personnel protection and special handling measures. Storage
should be provided to hold the process product streams until
they have been tested to determine their acceptability for
disposal or release. Depending upon the site, a method to store
waste that has been prepared for treatment may also be
necessary. Storage capacity will depend on waste volume.
Onsite analytical equipment capable of determining the re-
Engineerlng Bulletin: Thermal Desorption Treatment
-------
sidual concentration of organic compounds in process residuals
makes the operation more efficient and provides better informa-
tion for process control.
Performance Data
Performance data in this bulletin are included as a general
guideline to the performance of the thermal desorption technol-
ogy and may not always be directly transferable to other
Superfund sites. Thorough site characterization and treatability
studies are essential in determining the potential effectiveness of
the technology at a particular site. Most of the data on thermal
desorption come from studies conducted for EPA's Risk Reduc-
tion Engineering Laboratory under the Superfund Innovative
Technology Evaluation (SITE) Program.
Seaview Thermal Systems (formerly T.D.I. Services, Inc.)
conducted a pilot-scale test of their HT-5 thermal desorption
system at the U.S. DOE's Y-12 plant at Oak Ridge, Tennessee.
The test was run to evaluate the capability of the unit to remove
and recover mercury from a soil matrix. Initial mercury concen-
trations in the soil were 1,140 mg/kg. The mercury was
removed to concentrations of 0.19 mg/kg with a detection limit
of 0.03 mg/kg. A full-scale cleanup (80 tons per day) using the
HT-S system, was conducted for Chevron U.S.A. at their El
Segundo Refinery. The primary contaminants and their initial
and final concentrations are indicated in Table 3 [20].
In September 1992, an EPA SITE demonstration was per-
formed at a confidential Arizona pesticide site using Canonic
Environmental'* Low Temperature Thermal Aeration (LTTA®)
system. The unit had a 35-ton-per-hour capacity. Approximate-
ly 1,180 tons of pesticide-contaminated soil were treated during
the demonstration over three 10-hour replicate runs. The
primary pesticides were di(chlorophenyl) trichloroethane
(DDT), di(chlorophenyl)dichloroethene (DDE), di(chlorophenyl)
dichloroethane (ODD), and toxaphene. Concentrations of
pesticides in contaminated soils ranged from 7,080 tig/kg to
1,540,000 ng/kg. The LTTA* system obtained pesticide re-
moval efficiencies ranging from 82.4 percent to greater than
99.9 percent. All pesticides, with the exception of DDE, were
removed to near or below method detection limits in the soil.
Table 4 presents a summary of four case studies involving full-
scale applications of the LTTA* process [21].
An EPA SITE demonstration was performed at the Anderson
Development Company (ADC) Superfund site in Adrian, Michi-
gan using Roy F. Weston's Low Temperature Thermal Treatment
(LT3®) system. The unit had a 2.1-ton-per-hour capacity.
Approximately 80 tons of contaminated sludge were treated
during the demonstration which consisted of six 6-hour repli-
cate tests. The lagoon sludge was primarily contaminated with
VOCs and SVOCs, including 4,4'-methylenebis(2-chloroaniline)
(MBOCA). Initial VOC concentrations ranged from 35 to
25,000 ng/kg. In the treated sludge, VOC concentrations were
below method detection limits (less than 30 ng/kg) for most
compounds. MBOCA concentrations in the untreated sludge
ranged from 43.6 to 960 mg/kg. The treated sludge ranged in
concentration from 3 to 9.6 mg/kg. The LT3® system also
decreased the concentration of all SVOCs present in the sludge,
with two exceptions: chrysene and phenol. The increase of
Tab!* 3
Full-Scale Cleanup Results of the H-T-5 System [20]
Contaminant
Toluene
Benzene
Ethylbenzene
Xylenes
Naphthalene
2-Methylnaphthalene
Acenaphthlene
Phenanthrene
Anthracene
Pyrene
Benzo(a)Anthracene
Chrysene
Styrene
feed Soil
Concentration
(mg/kg)
30
38
93
290
550
1400
57
320
320
38
36
45
13
Treated Soil
Contentratlon
(^g/kg)
<620
<620
<620
<620
<620
<330
<330
<330
<330
<330
<330
<330
<620
Kemovoi
Efficiency
(%)
<97.93
<98.36
<99.79
<99.78
<99.89
<99.98
<99.42
<99.90
<99.90
<99.13
<99.08
<99.27
<99.23
chrysene concentration was likely caused by a minor leak of heat
transfer fluid. Chemical transformations during heating likely
caused the phenol concentrations to increase. PCDDs and
PCDFs were formed in the system, but were removed from the
exhaust gas by the unit's vapor-phase carbon column with
removal efficiencies, varying with congener, from 20 to 100
percent. Paniculate concentrations in the stack gas ranged from
less than 8.5 x 10"4 to6.7x 10'3 grains per dry standard cubic
meter (gr/dscm) and paniculate emissions ranged from less
than 1.2 x 10"4 to 9.2 x 10"4 pounds per hour. Table 5 presents
a summary of three case studies involving pilot- and full-scale
applications of the LT3® system [22].
In May 1991, an EPA SITE demonstration was performed at
the Wide Beach Development site in Brand, New York using Soil
Tech's Anaerobic Thermal Processor (ATP) system. Approxi-
mately 104 tons of contaminated soil were treated during three
replicate test runs. The soil and sediment at the site were
primarily contaminated with PCBs, along with VOCs and SVOCs.
The average total PCB concentration was reduced from 28.2
mg/kg in the contaminated soil and sediment to 0.043 mg/kg
in the treated soil (a 99.8 percent removal efficiency). The test
indicated that an average concentration of 23.1 jig/dscm of
PCBs was discharged from the unit's stack to the atmosphere.
The high PCB concentrations in the emissions may have been
caused by low removal efficiencies in the unit's vapor phase
carbon system, high paniculate loadings (0.467 gr/dscm) in the
stack, or a combination of the two. Low levels of dioxins and
furans were present in the feed soil, but none were detected in
the treated soils, baghouse fines, or the cyclone's flue gas. The
2,3,7,8-TCDD toxicity equivalents (TEOJ of the stack gas ranged
from 0.0106 to 0.0953 ng/dscm [23].
In |une 1991, an EPA SITE demonstration test was per-
formed at the Waukegan Harbor Superfund site in Waukegan
Harbor, IL. The site was primarily contaminated with PCBs,
along with VOCs, SVOCs, and metals. Approximately 253 tons
Engineering Bulletin: Thermal Desorption Treatment
-------
Table 4
Full-Seal* Cleanup Results of the LTTA* System [21]
Site
South Kearney
McKin
Ottati and Goss
Cannon Bridgewater
Former Spencer
Kellogg Facility
Volume/Mass
Treated
16,000 tons
11,500 cubic yards
4,500 cubic yards
11,300 tons
6,500 tons
Primary
Contaminant(i)
Total VOCs
SVOCs
VOCJ
SVOCs
1. 1, 1 TCA
TCE
Tetrachloroethene
Toluene
Ethylbenzene
Total Xylenes
VOCs
Total VOCs
SVOCs
feed Soil
Concentration
(mg/kg)
308.2
0.7- 15
2.7 - 3,310
0.44-1.2
1 2-470
6.5 - 460
4.9-1200
>87 - 3,000
>50 - 440
>170->1100
5.30b
5.42
0.15-4.7
Treated Soil
Contentration
(mg/kg)
0.51
ND- 1.0
<0.05a
<0.33-0.51
<0.025
<0.025
<0.025
<0.025 -0.11
<0.025
<0.025 -0.14
<0.025
0.45
0.042 - <0.39
Average concentration
Maximum concentration
Table 5
Full-Scale Cleanup Results of the LT3* System [22]
Volume/Mass Primary
Site Treated Contaminant(i)
Confidential 1,000 cubic feet Benzene
Toluene
Xylene
Ethylbenzene
Napthalene
PAHs
Tinker AFB, OK 3,000 cubic yards Volatile*
Semivolatiles
Letterkenny Army Depot 7.5 tons Benzene
Trichloroethene
Tetrachloroethene
Xylene
Other VOCs
feed Soil
Concentration
1 ppm
24 ppm
110 ppm
20 ppm
4.9 ppm
0.890 - <6ppm
18ng/kg - 37,250 ug/kg
90 ug/kg - 53,000 yg/kg
590 ppm
2,680 ppm
1,420 ppm
27,200 ppm
39 ppm
Treated Soil
Contentration
5.2 ppb
5.2 ppb
<1 .0 ppb
4.8 ppb
<0.33 ppm
<330 - 590 ppb
0.1 (ig/L-2.3ng/L
6 ng/L - <500 jig/L
0.73 ppm
1 .8 ppm
1.4 ppm
0.55 ppm
BDL
BDL Below detection limits
Engineering Bulletin: Thermal Desorption Treatment
-------
of contaminated soil were treated during four runs using Soil
Tech's ATP thermal desorption system. The system used was a
combination thermal desorption and dechlorination process.
The average PCB concentration in the feed soil was 9,173 mg/
kg; the average final concentration was 2 mg/kg, which is a
99.98 percent removal efficiency. The concentration of PCBs
in the stack gas was 0.834 jig/dscm (a 99.999987 percent
removal efficiency). Tetrachlorinated dibenzofurans were the
only dioxins and furans detected in the stack gas at an average
concentration of 0.0787 ng/dscm. The total concentration of
SVOCs in the feed soil was 61.8 mg/kg. In the treated soils
SVOC concentrations totaled only 8.52 mg/kg; only two samples
were identified below the detection limit. In the contaminated
soil, VOC concentrations totaled 17 mg/kg; while in the treated
soil the total was only 0.03 mg/kg. Concentrations of metals
were approximately the same in both the contaminated and
treated soil. -This was because the unit does not operate at
temperatures high enough to significantly remove metals. The
pH of the soil rose from 8.59 in the contaminated soil to 11.35
in the treated soil. This was likely due to the addition of sodium
bicarbonate used to reduce PCB emissions [23].
In May 1992, an EPA SITE demonstration was performed
at the Re-Solve Superfund site in North Dartmouth, Massachu-
setts using the Chemical Waste Management X'TRAX™ sys-
tem. The unit had a capacity of 4.9 tons per hour. Approxi-
mately 215 tons of contaminated soil were treated over a
period of three duplicate 6-hour tests. The soil is primarily
contaminated with PCBs, along with some oil and grease and
metals. Initial PCB concentrations ranged from 181 to 515 mg/
kg. The PCB concentration in the treated soil was less than 1.0
mg/kg with an average concentration of 0.25 mg/kg (a 99.9
percent removal efficiency). PCDDs and PCDFs were not
formed during the demonstration. Concentrations of oil and
grease, total recoverable petroleum hydrocarbons, and tetra-
chloroethane were reduced to below detectable levels. Metal
concentrations were not reduced during the test. This was
expected because the unit does not operate at temperatures
high enough to significantly remove metals [24].
RCRA LDRs that require treatment of wastes to best dem-
onstrated available technology (BDAT) levels prior to land
disposal may sometimes be determined to be applicable or
relevant and appropriate requirements for CERCLA response
actions. Thermal desorption often can produce a treated waste
that meets treatment levels set by BOAT but may not reach
these treatment levels in all cases. The ability to meet required
treatment levels is dependent upon the specific waste constit-
uents, the waste matrix, and the thermal desorption system
operating parameters. In cases where thermal desorption does
not meet these levels, it still may, in certain situations, be
selected for use at the site if a treatability variance establishing
alternative treatment levels is obtained. Treatability variances
are justified for handling complex soil and debris matrices. The
following guides describe when and how to seek a treatability
variance for soil and debris: Superfund LDR Guide #6A,
"Obtaining a Soil and Debris Treatability Variance for Remedial
Actions' (OSWER Directive 9347.3-06FS, September 1990)
[12], and Superfund LDR Guide #6B, "Obtaining a Soil and
Debris Treatability Variance for Removal Actions' (OSWER
Directive 9347.3-06BFS, September 1990) [13].
Technology Status
Several firms have experience in implementing this tech-
nology. Therefore, there should not be significant problems of
availability. The engineering and configuration of the systems
are similarly refined, so that once a system is designed full-scale,
little or no prototyping or redesign is generally required.
An EPA SITE demonstration took place at the end of 1993
at the Niagara Mohawk Power Corporation site in Utica, New
York. The facility is a former gas manufacturing plant Approxi-
mately 800 tons of contaminated soils were treated during the
demonstration. The soil is primarily contaminated with
polyaromatic hydrocarbons (PAHs); benzene, toluene,
ethylbenzene, and xylenes (BTEXs); lead; arsenic; and cyanide.
An EPA Innovation Technology Evaluation Report will be de-
veloped to evaluate the performance of and the cost to
implement the system.
Thermal desorption technologies are the selected reme-
dies at 31 Superfund sites. Table 6 presents the status of
selected Superfund sites employing the thermal desorption
technology [2].
Several vendors have experience in the operation of this
technology and have documented processing costs per ton of
feed processed. The overall range varies from approximately
SI00 to $400 (1993 dollars) per ton processed. Caution is
recommended in using costs out of context because the base
year of the estimates varies. Costs also are highly variable due
to the quantity of waste to be processed, terms of the remedia-
tion contract, moisture content, organic constituency of the
contaminated medium, and cleanup standards to be achieved.
Similarly, cost estimates should include such items as prepara-
tion of Work Plans, permitting, excavation, processing, QA/QC
verification of treatment performance, and reporting of data.
EPA Contacts
Technology-specific questions regarding thermal desorp-
tion may be directed to:
Paul dePercin
U.S. Environmental Protection Agency
Risk Reduction Engineering Laboratory
26 W. Martin Luther King Drive
Cincinnati, Ohio 45268
(513)569-7797
lames Yezzi
U.S. Environmental Protection Agency
Risk Reduction Engineering Laboratory
Releases Control Branch
2890 Woodbridge Avenue
Building 10(MS-104)
Edison, N| 08837
Engineering Bulletin: Thermal Desorption treatment
-------
Table 6
Supertund Sites Specifying Thermal Desorptlon as the Remediation Technology [2]
Jrtr
Location (Region)
Primary Contaminants
Status
Cannons/Bridgewater
McKin
Ottati & Goss
Wide Beach Development
Metaltec/Aerosyitems
Caldwell Trucking
Bridgewater, MA (1)
McKin, ME(1)
New Hampshire (1)
Brandt, NY (2)
Franklin Borough, Nj (2)
Fairfield, N| (2)
Outboard Marine/Waukegan Harbor Waukegan Harbor, IL (5)
Reich Farms Dover Township, N) (2)
Re-Solve North Dartmouth, MA (1)
Waldick Aerospace Devices New jersey (2)
Wamchem Burton, SC (4)
Fulton Terminals Fulton, Nj (2)
Anderson Development Company Adrian, Ml (5)
VOCs (Benzene, TCE, Toluene,
Vinyl Chloride)
VOCs (TCE, BTX)
VOCs, (TCE, PCE, 1,2-DCE, Benzene)
PCBs
VOCs (TCE)
VOCs (TCE, PCE, TCA)
PCBs
VOCs (TCE, PCE, TCA), SVOCs
PCBs
VOCs (TCE, PCE), Metals (Cadimum,
Chromium)
VOCs, BTX
VOCs (Xylene, TCE, Benzene, DCE)
VOCs, SVOCs
Site remediated 10/90
Site remediated 2/87
Site remediated 9/89
Site remediated 6/92
Design completed
Design completed
Site remediated 6/92
Pre-design
Pilot study completed 5/92
Design completed
In design
In design .
Site remediated 12/92
Note: The two Stauffer Chemical sites in Table 10 of the original Engineering Bulletin are not included in this table because EPA's
FY 1990 ROD Annual Report indicates that thermal desorption will no longer be implemented.
(908)321-6703
Acknowledgments
This updated bulletin was prepared for the U.S. Environ-
mental Protection Agency, Office of Research and Develop-
ment (ORD), Risk Reduction Engineering Laboratory (RREL),
Cincinnati, Ohio, by Science Applications International Corpo-
ration (SAIQ under Contract No. 68-CO-00-48. Mr. Eugene
Harris served as the EPA Technical Project Monitor. Mr. Jim
Rawe (SAIQ was the Work Assignment Manager. He and Mr.
Eric Savior (SAIQ co-authored the revised bulletin. The authors
are especially grateful to Mr. Paul dePercin of EPA-RREL, who
contributed significantly by serving as a technical consultant
during the development of this document. The authors also
want to acknowledge the contributions of those who partici-
pated in the development of and are listed in the original
bulletin.
The following other contractor personnel have contrib-
uted their time and comments by participating in the expert
review of the document
Mr. William Troxler
Dr. Steve Lanier
Focus Environmental, Inc.
Energy and Environmental
Research Corp.
8
Engineering Bulletin: Thermal Desorption Treatment
-------
REFERENCES
1. Thermal Desorption Treatment Engineering Bulletin.
U.S. Environmental Protection Agency, EPA/540/2-91/
008, May 1991.
2. Innovative Treatment Technologies. Semi-Annual Status
Report (Fourth Edition), U.S. Environmental Protection
Agency, EPA/542/R-92/011, October 1992.
3. Abrishamian, Ramin. Thermal Treatment of Refinery
Sludges and Contaminated Soils. Presented at American
Petroleum Institute, Orlando, Florida, 1990.
4. Swanstrom, C, and C. Palmer. XTRAX™ Transportable
Thermal Separator for Organic Contaminated Solids.
Presented at Second Forum on Innovative Hazardous
Waste Treatment Technologies: Domestic and Interna-
tional, Philadelphia, Pennsylvania, 1990.
5. Canonic Environmental Services Corp. Low Temperature
Thermal Aeration (LTTA*) Marketing Brochures, circa
1990.
6. VISITT Database, U.S. Environmental Protection Agency,
1993.
7. Nielson, R., and M. Cosmos. Low Temperature Thermal
Treatment (LT3*) of Volatile Organic Compounds from
Soil: A Technology Demonstrated. Presented at the
American Institute of Chemical Engineers Meeting, Den-
ver, Colorado, 1988.
8. Technology Screening Guide for Treatment of CERCLA
Soils and Sludges. U.S. Environmental Protection
Agency, EPA/540/2-88/004, 1988.
9. Considerations for Evaluating the Impact of Metals Parti-
tioning During the Incineration of Contaminated Soils
from Superfund Sites. Superfund Engineering Issue. U.S.
Environmental Protection Agency, EPA/540/S-92/014,
September 1992.
10. T.D.I. Services. Marketing Brochures, circa 1990.
11. Cudahy, ]., and W. Troxler. 1990. Thermal Remediation
Industry Update - II. Presented at Air and Waste Man-
agement Association Symposium on Treatment of Con-
taminated Soils, Cincinnati, Ohio, 1990.
12. Superfund LDR Guide #6A: (2nd Edition) Obtaining a
Soil and Debris Treatability Variance for Remedial Ac-
tions. Superfund Publications 9347.3-06FS, U.S. Envi-
ronmental Protection Agency, 1990.
13. Superfund LDR Guide #6B: Obtaining a Soil and Debris
Treatability Variance for Removal Actions. Superfund
Publications 9347.3-06BFS, U.S. Environmental Protec-
tion Agency, 1990.
14. Guide for Conducting Treatability Studies under
CERCLA: Thermal Desorption Remedy Selection, In-
terim Guidance. U.S. Environmental Protection Agency,
EPA/540/R-92/074A, September 1992.
15. Recycling Sciences International, Inc., DAVES Marketing
Brochures, circa 1990.
16. The Superfund Innovative Technology Evaluation Pro-
gram- Progress and Accomplishments Fiscal Year 1989,
A Third Report to Congress. U.S. Environmental Pro-
tection Agency, EPA/540/5-90/001, 1990.
17. Superfund Treatability Clearinghouse Abstracts. U.S.
Environmental Protection Agency, EPA/540/2-89/001,
1989.
18. Soil Tech, Inc. AOSTRA - Taciuk Processor Marketing
Brochure, circa 1990.
19. Ritcey, R., and F. Schwartz. Anaerobic Pyrolysis of
Waste Solids and Sludges - The AOSTRA Taciuk Process
System. Presented at Environmental Hazards Confer-
ence and Exposition, Seattle, Washington, 1990.
20. Seaview Thermal Systems. Marketing Brochures, circa
1993.
21. Low Temperature Thermal Treatment Aeration (LTTA®)
Technology. Canonic Environmental Services Corpora-
tion. Applications Analysis Report, U.S. Environmental
Protection Agency (Draft-March 1993).
22. Roy F. Weston, Inc. Low Temperature Thermal Treat-
ment (LT3*) System. Applications Analysis Report
Anderson Development Company Site. U.S. Environ-
mental Protection Agency, EPA/540/AR-92/019, Decem-
ber 1992.
23. Soil Tech ATP Systems, Inc. Anaerobic Thermal Proces-
sor. Applications Analysis Report Wide Beach Develop-
ment Site and Outboard Marine Corporation Site. U.S.
Environmental Protection Agency (Preliminary Draft-
February 1993).
24. XTRAX™ Model 200 Thermal Desorption System.
Chemical Waste Management, Inc. Demonstration Bul-
letin, U.S. Environmental Protection Agency, EPA/540/
MR-93/502, February 1993.
Engineering Bulletin: Thermal Desorption Treatment
•frll-S. GOVLBNMENT PUNTING OFFICE: !**< - S30-»f7/iOI»S
-------
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/540/S-94/501
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Section 14
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IMMOBILIZATION
STUDENT PERFORMANCE OBJECTIVES
At the conclusion of this unit, students will be able to:
1. List two advantages of using immobilization
2. Describe the differences between solidification, stabilization,
and vitrification
3. Describe the following processes:
a. Cement-based stabilization
b. Pozzolan-based stabilization
c. Organic-based immobilization
4. Describe the vitrification process
5. Describe four tests used for classification of untreated wastes
6. Describe two methods of leach-testing stabilized waste
7. List the most common types of equipment used to remove
and mix wastes.
NOTE: Unless otherwise stated, the conditions for
performance are using all references and materials
provided in the course, and the standards of
performance are without error.
7/95
-------
IMMOBILIZATION
S-1
IMMOBILIZATION
Renders contaminants less soluble,
decreases mobility, and/or reduces
toxicity
Minimizes leaching from a solid matrix
Will be either chemical or thermal
S-2
IMMOBILIZATION
Advantages
• Improves waste handling
• Decreases exposed surface area of
contaminant
• Results in limited solubility or toxicity
• Uses readily available materials
• Has large number of suppliers
S-3
NOTES
7/95
Immobilization
-------
NOTES
IMMOBILIZATION
Disadvantages
Not a destructive technology
Increases waste volume
Unproven for long-term leachability
Ineffective treatment for organics
S-4
STABILIZATION OF
ORGANIC CONTAMINANTS
Contaminants may volatilize
Organics interfere with silicates and cement
S-5
STABILIZATION OF
ORGANIC CONTAMINANTS (cont.)
Organics must be compatible with polymers
and bitumen
Organics reduce effectiveness of
encapsulation
S-fl
Immobilization
7/95
-------
SOLIDIFICATION/STABILIZATION (S/S)
Binding Agents
• Inorganic - cement, lime, kiln dust,
flyash, silicates, clay,
and zeolites
• Organic - asphalt, polypropylene, and
polyethylene,.
S-7
LIMITATIONS WITH BINDING
AGENTS
May contain metal or organic
contaminants
- Cement and flyash can contain trace
metals such as Hg and Cd
- Asphalt can contain napthalenes and
other polycyclic organics
Composition may vary by source
S-8
SOLIDIFICATION
Physically holds liquid waste within
pores by capillary action or tension
Converts liquid or sludge to solid
Involves physical, rather than chemical,
reaction
S-8
NOTES
7/95
Immobilization
-------
NOTES
SOLIDIFICATION (cont.)
Materials used:
• Hydro- and organophilic clays -
Fuller's Earth and Bentonite
• Silicates - flyash and vermiculite
• Organic - saw dust and ground corn
cob
S-10
STABILIZATION
• Exothermic reaction occurs
• Calcium oxide or equivalent compound
must be present
• More solid, stable matrix produced
• Forms hydroxide precipitate
S-11
STABILIZATION (cont.)
Chemical bonding of waste and free
liquid with one of the following:
- Portland cement
- Pozzolanic materials (silicates with
lime) d&vu"
- Cement kiln dust
S-12
Immobilization
7/95
-------
NOTES
STABILIZATION PROCESSES
• Cement-based
• Pozzolan-based
• Organic-based
S-13
CEMENT-BASED S/S PROCESS
Waste is mixed with Portland cement or
cement kiln dust
Waste is incorporated into matrix
Waste is chemically bound, thereby
minimizing leaching
Secondary containment is needed for disposal
S-14
CEMENT-BASED S/S PROCESS
• Only effective for organics in low
concentrations (<2%)
• Incompatible wastes weaken matrix
• Examples: sodium salts of arsenate, borate,
phosphate, iodate, and sulfide
S-1S
7/95
Immobilization
-------
NOTES
PORTLAND CEMENT
Preparation: limestone, clays, and silicates
are fired in a rotary kiln at 3000°F
Cement kiln dust: a by-product of Portland
cement manufacturing
S-10
PORTLAND CEMENT (cont.)
Composition:
Calcium oxide
Silicon dioxide
Aluminum oxide
Iron oxide
Magnesium oxide
59-66%
14-22%
5-11%
2-3%
1 -2%
S-17
CEMENT-BASED STABILIZATION
Raw Materials
• Cement-based binding
- Portland cement
- Cement kiln
- Natural and artificial pozzolans
- Cement and flyash
S-18
Immobilization
7/95
-------
NOTES
CEMENT-BASED STABILIZATION
Raw Materials (cont.)
• Lime/limestone/quicklime
- Lime kiln dust
- Lime and flyash
S-18
POZZOLANIC STABILIZATION
Siliceous and aluminosilicate materials
Examples:
- Flyash
- Pumice
- Lime kiln dust
- Blast furnace slag
S-20
POZZOLANIC STABILIZATION
(cont.)
• Not cementitious alone
• Requires lime or cement to react
S-21
7/95
Immobilization
-------
NOTES
ARTIFICIAL POZZOLANS
Lime/Flyash Mixtures
Flyash supplies silica
Lime supplies Ca(OH)2
Results in properties chemically similar
to cement
S-22
IMMOBILIZATION WITH
ORGANIC BINDERS
• Primary use in radioactive or mixed wastes
• Limited use for hazardous wastes
• Organics in waste may react with binders
• Waste must be dry before mixing
• Encapsulation (micro and macro)
S-23
COMMON ORGANIC BINDERS
Asphalt/bitumen
Urea formaldehyde
Polyethylene
Polypropylene
S-24
Immobilization
7/95
-------
NOTES
VITRIFICATION
Definition
A thermal treatment process for destruction
and/or immobilization of contaminants within
a soil matrix
S-25
VITRIFICATION
Design Specifications
• Maximum and minimum area treated
• Fluxing material added
• Full-scale operation
- In-situ vitrification processes 4-6
tons/hour
- 0.3 to 0.5 kwh/lb of soil
- Dual phase system requires 1.9 Mw/phase
S-26
VITRIFICATION
Advantages
Waste fixed in a solid obsidian-like
monolith
Contaminant mobility limited
Process performed in situ or ex situ
S-27
7/95
Immobilization
-------
NOTES
VITRIFICATION
Disadvantages
Not a destruction technology for inorganics
Long-term leaching unknown
Only one vendor (GEOSAFE)
High energy consumption
8-28
IN-SITU VITRIFICATION
Application and Evaluation
• Inorganics, organics, and radioactive
wastes
• Soil matrix
• Costs: $250-350 per ton-
S-29
TESTING METHODS FOR
UNTREATED WASTES
• Particle size and distribution
• Moisture content - ASTM D2216-80
• Bulk density - ASTM D2937-83
S-30
Immobilization
10
7/95
-------
TESTING METHODS FOR
UNTREATED WASTES
Strength - unconfined
strength
Permeability - falling head or constant
head test
S-31
LEACH TEST METHODS
(Toxicity Characteristic Leaching
Procedure)
(Multiple Extraction Procedure)
S-32
TOXICITY CHARACTERISTIC
LEACHING PROCEDURE
• TCLP is standard EPA RCRA test
• Samples crushed to pass 9.5-mm screen
• Tumbled with acetic acid for 18 hrs
• Solids filtered and extract analyzed
• Water sometimes substituted for acetic
acid
S-33
NOTES
7/95
11
Immobilization
-------
NOTES
MULTIPLE EXTRACTION
PROCEDURE
• Used for delisting
• Multiple extractions - usually nine; more
possible if last three do not
decrease leachate concentrations
• Results used to determine maximum leachate
concentrations
S-34
LEACH TEST CONCLUSIONS
• Not directly applicable to leaching in
field
• Test results used as indicators only
S-35
BASIC IMPLEMENTATION
FIELD OPERATIONS
• Pretreatment
• Removal
• Storage
• Mixing
• Replacement
-I r>
S-3«
Immobilization
12
7/95
-------
REFERENCES
U.S. EPA. 1989. Immobilization Technology Seminar: Speaker Slide Copies and Supporting
Information. U.S. Environmental Protection Agency, Risk Reduction Engineering Laboratory,
Center for Environmental Research Information, Cincinnati, OH.
U.S. EPA. 1989. Stabilization/Solidification of CERCLA and RCRA Wastes: Physical Tests,
Chemical Testing Procedures, Technology Screening, and Field Activities. U.S. Environmental
Protection Agency, Office of Research and Development, Washington, DC.
U.S. EPA. 1993. Engineering Bulletin: Solidification/Stabilization of Organics and Inorganics.
EPA/540/S-92/015. U.S. Environmental Protection Agency, Office of Emergency and Remedial
Response, Washington, DC, and Office of Research and Development, Cincinnati, OH.
U.S. EPA. 1994. Engineering Bulletin: In Situ Vitrification Treatment. EPA/540/S-94/504. U.S.
Environmental Protection Agency, Office of Emergency and Remedial Response, Washington, DC.
7/95 13 Immobilization
-------
oEPA
• ^^_ .. .
Office of '„' .; >
R«earx-x wx'-^ " ^—% ^ -• '•v»^ mm -mm '
Engineering Bulletin
Soliprccfflon/Stdbilization
of Organics and Inorganics
Purpose
Section 121 (b) of the Comprehensive Environmental Re-
sponse, Compensation, and Liability Act (CERCLA) mandates
the Environmental Protection Agency (EPA) to select remedies
that "utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the maxi-
mum extent practicable" and to prefer remedial actions in
which treatment "permanently and significantly reduces the
volume, toxicity, or mobility of hazardous substances, pollut-
ants, and contaminants as a principal element' The Engineer-
ing Bulletins are a series of documents that summarize the most
current information available on selected treatment and site
remediation technologies and related issues. They provide
summaries of and references for this information to help reme-
dial project managers, on-scene coordinators, contractors, and
other site cleanup managers understand the type of data and
site characteristics needed to evaluate a technology for poten-
tial applicability to their Superfund or other hazardous waste
site. Those documents that describe individual treatment tech-
nologies focus on remedial investigation scoping needs. Ad-
denda are issued periodically to update the original bulletins.
granular consistency resembling soil. During in situ operations,
S/S agents are injected into and mixed with the waste and soil
up to depths of 30 to 100 feet using augers.
Treatability studies are the only means of documenting the
applicability and performance of a particular S/S system. Deter-
mination of the best treatment alternative will be based on
multiple site-specific factors and the cost and efficacy of the
treatment technology. The EPA contact identified at the end of
this bulletin can assist in the location of other contacts and
sources of information necessary for such treatability studies.
It may be difficult to evaluate the long-term (>5 year)
performance of the technology. Therefore, long-term monitor-
ing may be needed to ensure that the technology continues to
function within its design criteria.
This bulletin provides information on technology applica-
bility, the limitations of the technology, the technology descrip-
tion, the types of residuals produced, site requirements, the
process performance data, the status of the technology, and
sources for further information.
Abstract
Solidification refers to techniques that encapsulate hazard-
ous waste into a solid material of high structural integrity.
Encapsulation involves either fine waste particles
(microencapsulation) or a large block or container of wastes
(macroencapsulation) [1, p. 2]*. Stabilization refers to tech-
niques that treat hazardous waste by converting it into a less
soluble, mobile, or toxic form. Solidification/Stabilization (S/S)
processes, as referred to in this document, utilize one or both of
these techniques.
S/S technologies can immobilize many heavy metals, cer-
tain radionuclides, and selected organic compounds while de-
creasing waste surface area and permeability for many types of
sludge, contaminated soils, and solid wastes. Common S/S
agents include: Type 1 Portland cement or cement kiln dust;
lime, quicklime, or limestone; fly ash; various mixtures of these
materials; and various organic binders (e.g., asphalt). The
mixing of the waste and the S/S agents can occur outside of the
ground (ex situ) in continuous feed or batch operations or in
the ground (in situ) in a continuous feed operation. The final
product can be a continuous solid mass of any size or of a
'[reference number, page number]
Technology Applicability
The U.S. EPA has established treatment standards under
the Resource Conservation and Recovery Act (RCRA), Land
Disposal Restrictions (LDRs) based on Best Demonstrated Avail-
able Technology (BOAT) rather than on risk-based or health-
based standards. There are three types of LDR treatment
standards based on the following: achieving a specified con-
centration level, using a specified technology prior to disposal,
and "no land disposal." Achieving a specified concentration
level is the most common type of treatment standard. When a
concentration level to be achieved is specified for a waste, any
technology that can meet the standard may be used unless that
technology is otherwise prohibited [2].
The Superfund policy on use of immobilization is as fol-
lows: "Immobilization is generally appropriate as a treatment
alternative only for material containing inorganics, semi-volatile
and/or non-volatile organics. Based on present information,
the Agency does not believe that immobilization is an appropri-
ate treatment alternative for volatile organic compounds (VOCs).
Selection of immobilization of semi-volatile compounds (SVOCs)
and non-volatile organics generally requires the performance of
Printed on Recycled Paper
-------
a site-specific treatability study or non-site-specific treatabflity
study data generated on waste which is very similar On terms of
type of contaminant, concentration, and waste matrix) to that
to be treated and that demonstrates, through Total Waste
Analysis (TWA), a significant reduction (e.g., a 90 to 99 percent
reduction) in the concentration of chemical constituents of
concern. The 90 to 99 percent reduction in contaminant
concentration is a general guidance and may be varied within a
reasonable range considering the effectiveness of the technol-
ogy and the cleanup goals for the site. Although this policy
represents EPA's strong belief that TWA should be used to
demonstrate effectiveness of immobilization for organics, other
teachability tests may also be appropriate in addition to TWA to
evaluate the protectiveness under a specific management sce-
nario. To measure the effectiveness on inorganics, the EPA's
Toxicity Characteristic Leaching Procedure (TCLP) should be
used in conjunction with other tests such as TCLP using distilled
water or American Nuclear Society (ANS) 16.1 [3, p. 2].
Factors considered most important in the selection of a
technology are design, implementation, and performance of
S/S processes and products, including the waste characteristics
(chemical and physical), processing requirements, S/S product
management objectives, regulatory requirements, and econom-
ics. These and other site-specific factors (e.g., location, condi-
tion, climate, hydrology, etc.) must be taken into account in
determining whether, how, where, and to what extant a par-
ticular S/S method should be used at a particular site [4, p.
7.92]. Pozzolanic S/S processes can be formulated to set under
water if necessary; however, this may require different propor-
tions of fixing and binding agents to achieve the desired immo-
bilization and is not generally recommended [5, p. 21]. Where
non-pumpable sludge or solid wastes are encountered, the site
must be able to support the heavy equipment required for
excavation or in situ injection and mixing. At some waste
disposal sites, this may require site engineering.
A wide range of performance tests may be performed in
conjunction with S/S treatability studies to evaluate short- and
long-term stability of the treated material. These include total
waste analysis for organics, teachability using various methods,
permeability, unconfined compressive strength (DCS), treated
waste and/or leachate toxicity endpoints, and freeze/thaw and
wet/dry weathering cycle tests performed according to specific
procedures [6, p. 4.2] [7, p. 4.1]. Treatability studies should be
conducted on replicate samples from a representative set of
waste batches that span the expected range of physical and
chemical properties to be encountered at the site [8, p. 1].
The most common fixing and binding agents for S/S are
cement, lime, natural pozzolans, and fly ash, and mixtures of
these [4, p. 7.86] [6, p. 2.1]. They have been demonstrated to
immobilize many heavy metals and to solidify a wide variety of
wastes including spent pickle liquor, contaminated soils, incin-
erator ash, wastewater treatment filter cake, and waste sludge
[7, p. 3.1] [9]. S/S is also effective in immobilizing many
radionuclides [10]. In general, S/S is considered an established
full-scale technology for nonvolatile heavy metals although the
long-term performance of S/S in Superfund applications has yet
to be demonstrated [2].
Traditional cement and pozzolanic materials have yet to be
shown to be consistently effective in full-scale applications treat-
ing wastes high in oil and grease, surfactants, or chelating
agents without some form of pretreatment [11] [12, p. 122].
Pretreatment methods include pH adjustment, steam or ther-
mal stripping, solvent extraction, chemical or photochemical
reaction, and biodegradation. The addition of sorbents such as
modified day or powdered activated carbon may improve ce-
ment-based or pozzolanic process performance [6, p. 2.3].
Regulations promulgated pursuant to the Toxic Substances
Control Act (TSCA) do not recognize S/S as an approved treat-
ment for wastes containing polychlorinated biphenyls (PCBs)
above SO ppm. It is EPA policy that soils containing greater
than 10 ppm in public/residential areas and 25 ppm in limited
access/occupational areas be removed forTSCA-approved treat-
ment/disposal. However, the policy also provides EPA regional
offices with the option of requiring more restrictive levels. For
example, Region 5 requires a cleanup level of 2 ppm. The
proper disposition of high volume sludges, soils, and sediments
is not specified in the TSCA regulations, but precedents set in
the development of various records of decision (RODs) indicate
that stabilization may be approved where PCBs are effectively
immobilized and/or destroyed to TSCA-equivalent levels. Some
degree of immobilization of PCBs and related polychlorinated
polycydic compounds appears to occur in cement or pozzolans
[15, p. 1573]. Some field observations suggest polychlorinated
polycydic organic substances such as PCBs undergo significant
levels of dechlorination under the alkaline conditions encoun-
tered in pozzolanic processes. Recent tests by the EPA, how-
ever, have not confirmed these results although significant
desorption and volatilization of the PCBs were documented
[13, p. 41] [14, p. 3].
Table 1 summarizes the effectiveness of S/S on general
contaminant groups for soils and sludges. Table 1 was pre-
pared based on current available information or on professional
judgment when no information was available. In interpreting
this table, the reader is cautioned that for some primary con-
stituents, a particular S/S technology performs adequately in
some concentration ranges but inadequately in others. For
example, copper, lead, and zinc are readily stabilized by
cementitious materials at low to moderate concentrations, but
interfere with those processes at higher concentrations [12, p.
43]. In general, S/S methods tend to be most effective for
immobilizing nonvolatile heavy metals.
The proven effectiveness of the technology for a particular
site or waste does not ensure that it will be effective at all sites or
that treatment efficiencies achieved will be acceptable at other
sites. For the ratings used in Table 1, demonstrated effective-
ness means that at some scale, treatability tests showed that the
technology was effective for that particular contaminant and
matrix. The ratings of "Potential Effectiveness* and "No Ex-
pected Effectiveness* are both based upon expert judgment
When potential effectiveness is indicated, the technology is
believed capable of successfully treating the contaminant group
in a particular matrix. When the technology is not applicable or
will probably not work for a particular combination of contami-
nant group and matrix, a no expected effectiveness rating is
given.
Engineering Bulletin: Solidification/Stabilization of Organics and Inorganics
-------
Tabtol
Eff«cflv«n«ss of S/S on General Contaminant
Groups for Soil and Sludgos
I
5
I
5
*
„
|
Contaminant Groups
Halogenated volatile
Nonhalogenated volatiles
Halogenated semivolatiles
Nonhalogenated semivolatiles
and nonvolatile!
PCBs
Pesticides
Dioxins/Furans
Organic cyanides
Organic corrosives
Volatile metals
Nonvolatile metals
Asbestos
Radioactive materials
Inorganic corrosives
Inorganic cyanides
Oxidizers
Reducers
Effectiveness
Soil/Sludge
Q
0
•
1
T
V
T
T
T
KEY: • Demonstrated Effectiveness: Successful treatability test
at some scale completed.
T Potential Effectiveness: Expert opinion that
technology will work.
O No Expected Effectiveness: Expert opinion that
technology will/does not work.
Another source of general observations and average re-
moval efficiencies for different treatability groups is contained
in the Superfund LOR Guide #6A, "Obtaining a Soil and Debris
Treatability Variance for Remedial Actions," (OSWER Directive
9347.3-06FS, September 1990) [16] and Superfund LDR Guide
#6B, "Obtaining a Soil and Debris Treatability Variance for
Removal Actions," (OSWER Directive 9347.3-06BFS, Septem-
ber 1990) [17]. Performance data presented in this bulletin
should not be considered directly applicable to other Superfund
sites. A number of variables such as the specific mix and
distribution of contaminants affect system performance. A
thorough characterization of the site and a well-designed and
conducted treatability study are highly recommended.
Other sources of information include the U.S. EPA's Risk
Reduction Engineering Laboratory Treatability Database (acces-
sible via ATTIC) and the U.S. EPA Center Hill Database (contact
Patricia Erickson).
Technology Limitations
Tables 2 and 3 summarize factors that may interfere with
stabilization and solidification processes respectively.
Physical mechanisms that can interfere with the S/S pro-
cess include incomplete mixing due to the presence of high
moisture or organic chemical content resulting in only partial
wetting or coating of the waste particles with the stabilizing
and binding agents and the aggregation of untreated waste
into lumps [6]. Wastes with a high day content may dump,
interfering with the uniform mixing with the S/S agents, or the
day surface may adsorb key reactants, interrupting the poly-
merization chemistry of the S/S agents. Wastes with a high
hydrophilic organic content may interfere with solidification by
disrupting the gel structure of the curing cement or pozzolanic
mixture [11, p. 18] [18]. The potential for undermixing is
greatest for dry or pasty wastes and least for freely flowing
slurries [11, p. 13]. All in situ systems must provide for the
introduction and mixing of the S/S agents with the waste in the
proper proportions in the surface or subsurface waste site envi-
ronment Quality control is inherently more difficult with in situ
products than with ex situ products [4, p. 7.95].
Chemical mechanisms that can interfere with S/S of ce-
ment-based systems indude chemical adsorption, complex-
ation, precipitation, and nucleation [1, p. 82]. Known inor-
ganic chemical interferants in cement-based S/S processes
indude copper, lead, and zinc, and the sodium salts of arsen-
ate, borate, phosphate, iodate, and sutfide [6, p. 2.13] [12, p.
11]. Sutfate interference can be mitigated by using a cement
material with a low tricalcium aluminate content (e.g., Type V
Portland cement) [6, p. 2.13]. Problematic organic interferants
indude oil and grease, phenols [8, p. 19], surfactants, dictating
agents [11, p. 22], and ethytene glycol [18]. For thermoplastic
micro- and macro-encapsulation, stabilization of a waste con-
taining strong oxidizing agents reactive toward rubber or as-
phalt must also be avoided [19, p. 10.114]. Pretreating the
wastes to chemically or biochemically react or to thermally or
chemically extract potential interferants should minimize these
problems, but the cost advantage of S/S may be lost, depend-
ing on the characteristics and volume of the waste and the type
and degree of pretreatment required. Organic polymer addi-
tives in various stages of development and field testing may
significantly improve the performance of the cementitious and
pozzolanic S/S agents with respect to immobilization of organic
substances, even without the addition of sorbents.
Volume increases associated with the addition of S/S agents
to the waste may prevent returning the waste to the landform
from which it was excavated where landfill volume is limited.
Where post-dosure earthmoving and landscaping are required,
the treated waste must be able to support the weight of heavy
equipment The EPA recommends a minimum compressive strength
of 50 to 200 psi [7, p. 4.13]; however, this should be a site-specific
determination.
Environmental conditions must be considered in determin-
ing whether and when to implement an S/S technology. Ex-
tremes of heat, cold, and precipitation can adversely affect S/S
applications. For example, the viscosity of one or more of the
Engineering Bulletin: Solidification/Stabilization of Organic* and Inorganics
-------
Table 2.
Summary of Factors that May Interfere with Stabilization Processes *
Characteristics Affecting Processing Feasibility
VOCs
Use of acidic sorbent with metal hydroxide wastes
Use of acidic sorbent with cyanide wastes
Use of acidic sorbent with waste containing ammonium compounds
Use of acidic sorbent with sulfide wastes
Use of alkaline sorbent (containing carbonates such as calcite
or dolomite) with acid waste
Use of siliceous sorbent (soil, fly ash) with hydrofluoric acid waste
Presence of anions in acidic solutions that form soluble
calcium salts (e.g., calcium chloride acetate, and bicarbonate)
Presence of halides
Potential Interference
Volatiles not effectively immobilized; driven off by heat of reaction.
Sludges and soils containing volatile organics can be treated using a
heated extruder evaporator or other means to evaporate free water and
VOCs prior to mixing with stabilizing agents.
Solubilizes metal.
Releases hydrogen cyanide.
Releases ammonia gas.
Releases hydrogen sulfide.
May create pyrophoric waste.
May produce soluble fluorosilicates.
Cation exchange reactions - leach calcium from S/S product
increases permeability of concrete, increases rate of exchange
reactions.
Easily leached from cement and lime.
Adapted from reference 2
Tables.
Summary of Factors that May Interfere with Solidification Processes *
Characteristics Affecting
Processing Feasibility
Organic compounds
Semivolatile organic* or poly-
aromatic hydrocarbons
(PAHs)
Oil and grease
Fine particle size
Halides
Soluble salts of manganese,
tin, zinc, copper, and lead
Cyanides
Sodium arsenate, berates,
phosphates, iodates, sulfides,
and carbohydrates
Sulfates
Potential Interference
Organics may interfere with bonding of waste materials with inorganic binders.
Organic* may interfere with bonding of waste materials.
Weaken bonds between waste particles and cement by coating the particles. Decrease in unconfined
compressive strength with increased concentrations of oil and grease.
Insoluble material passing through a No. 200 mesh sieve can delay setting and curing. Small particles
can also coat larger particles, weakening bonds between particles and cement or other reagents.
Particle size >1/4 inch in diameter not suitable.
May retard setting, easily leached for cement and pozzolan S/S. May dehydrate thermoplastic
solidification.
Reduced physical strength of final product caused by large variations in setting time and reduced
dimensional stability of the cured matrix, thereby increasing teachability potential.
Cyanides interfere with bonding of waste materials.
Retard setting and curing and weaken strength of final product
Retard setting and cause swelling and spading in cement S/S. With thermoplastic solidification may
dehydrate and rehydrate, causing splitting.
' Adapted from reference 2
Engineering Bulletin: SoilaTficaHon/Stabaizarion of Organics and Inorganics
-------
Tab* 3
Summary of Factors that May Interfere with SoUdfflcaUon Processes * (continued)
Characteristics Affecting
Processing Feasibility
Phenols
Presence of coal or lignite
Sodium borate, calcium
surfate, potassium
bichromate, and
carbohydrates
Nonpolar organic* (oil,
grease, aromatic
hydrocarbons, PCBs)
Polar organics (alcohols,
phenols, organic acids,
gtycols)
Solid organics (plastics, tars,
resins)
Oxidizers (sodium
hypochlorite, potassium
permanganate, nitric acid,
or potassium dichromate)
Metals (lead, chromium,
cadmium, arsenic, mercury)
Nitrates, cyanides
Soluble salts of magnesium,
tin, zinc, copper and lead
Environmental/waste
conditions that lower the
pH of matrix
Flocculants (e.g., ferric
chloride)
Soluble sutfates>0.01% in
soil or 1 50 mg/L in water
Soluble sulfates >0.5% in
soil or 2000 mg/L in water
Oil, grease, lead, copper,
zinc, and phenol
Aliphatic and aromatic
hydrocarbons
Chlorinated organics
Metal salts and complexes
Inorganic acids
Inorganic bases
Potential Interference
Marked decreases in compressive strength for high phenol levels.
Coals and lignites can cause problems with setting, curing, and strength of the end product
Interferes with pozzolanic reactions that depend on formation of calcium silicate and aluminate
hydrates.
May impede setting of cement, pozzolan, or organic-polymer S/S. May decrease long-term durability
and allow escape of volatile* during mixing. With thermoplastic S/S, organics may vaporize from heat
With cement or pozzolan S/S, high concentrations of phenol may retard setting and may decrease short-
term durability; all may decrease long-term durability. With thermoplastic S/S, organics may vaporize.
Alcohols may retard setting of pozzolans.
Ineffective with urea formaldehyde polymers; may retard setting of other polymers.
May cause matrix breakdown or fire with thermoplastic or organic polymer S/S.
May increase setting time of cements If concentration is high.
Increase setting time, decrease durability for cement-based S/S.
May cause swelling and cracking within inorganic matrix exposing more surface area to leaching.
Eventual matrix deterioration.
Interference with setting of cements and pozzolans.
Endangerment of cement products due to sulfur attack.
Serious effects on cement products from sulfur attacks.
Deleterious to strength and durability of cement, lime/fly ash, fly ash/cement binders.
Increase set time for cement
May increase set time and decrease durability of cement if concentration is high.
Increase set time and decrease durability for cement or clay/cement
Decrease durability for cement (Portland Type 1) or clay/cement.
Decrease durability for clay/cement; KOH and NaOH decrease durability for Portland cement Type III
and IV.
' Adapted from reference 2
Engineering Bulletin: Solidification/Stabilization of Organics and Inorganics
-------
materials in the mixture may increase rapidly with falling tem-
peratures or the cure rate may be slowed unacceptably [20, p.
27]. In cement-based S/S processes the engineering properties
of the concrete mass produced for the treatment of the waste
are highly dependent on the water/cement ratio and the de-
gree of hydration of the cement High water/cement ratios
yield large pore sizes and thus higher permeabilities [21, p.
177]. This factor may not be readily controlled in environmen-
tal applications of S/S and pretreatment (e.g., drying) of the
waste may be required.
Depending on the waste and binding agents involved, S/S
processes can produce hot gases, including vapors that are
potentially toxic, irritating, or noxious to workers or communi-
ties downwind from the processes [22, p. 4]. Laboratory tests
demonstrate that as much as 90 percent of VOCs are volatilized
during solidification and as much as 60 percent of the remain-
ing VOCs are lost in the next 30 days of curing [23, p. 6]. In
addition, if volatile substances with low flash points are in-
volved, the potential exists for fire and explosions where the
fuel-to-air ratio is favorable [22, p. 4]. Where volatization
problems are anticipated, many S/S systems now provide for
vapor collection and treatment Under dry and/or windy envi-
ronmental conditions, both ex situ and in situ S/S processes are
likely to generate fugitive dust with potentially harmful impacts
on occupational and public health, especially for downwind
communities.
Scaleup for S/S processes from bench-scale to full-scale
operation involves inherent uncertainties. Variables such as
ingredient flow-rate control, materials mass balance, mixing,
and materials handling and storage, along with the weather
compared to the more controlled environment of a laboratory,
all may affect the success of a field operation. These potential
engineering difficulties emphasize the need for a field demon-
stration prior to full-scale implementation [2].
Technology Description
Waste stabilization involves the addition of a binder to a
waste to immobilize waste contaminants effectively. Waste
solidification involves the addition of a binding agent to the
waste to form a solid material. Solidifying waste improves its
material handling characteristics and reduces permeability to
leaching agents such as water, brine, and inorganic and or-
ganic acids by reducing waste porosity and exposed surface
area. Solidification also increases the load-bearing capacity of
the treated waste, an advantage when heavy equipment is
involved. Because of their dilution effect, the addition of bind-
ers must be accounted for when determining reductions in
concentrations of hazardous constituents in S/S treated waste.
S/S processes are often divided into the following broad
categories: inorganic processes (cement and pozzolanic) and
organic processes (thermoplastic and thermosetting). Generic
S/S processes involve materials that are well known and readily
available. Commercial vendors have typically developed ge-
neric processes into proprietary processes by adding special
additives to provide better control of the S/S process or to
enhance specific chemical or physical properties of the treated
waste. Less frequently, S/S processes combine organic binders
with inorganic binders (e.g., diatomaceous earth and cement
with polystyrene, polyurethane with cement and polymer gels
with silicate and lime cement) [2].
The waste can be mixed in a batch or continuous system
with the binding agents after removal (ex situ) or in place (in-
situ). In ex situ applications, the resultant slurry can be 1)
poured into containers (e.g., 55-gallon drums) or molds for
curing and then off- or onsite disposal, 2) disposed in onsite
waste management cells or trenches, 3) injected into the sub-
surface environment or 4) re-used as construction material
with the appropriate regulatory approvals. In in situ applica-
tions, the S/S agents are injected into the subsurface environ-
ment in the proper proportions and mixed with the waste
using backhoes for surface mixing or augers for deep mixing
[5]. Liquid waste may be pretreated to separate solids from
liquids. Solid wastes may also require pretreatment in the form
of pH adjustment, steam or thermal stripping, solvent extrac-
tion, chemical reaction, or biodegradation to remove excessive
VOCs and SVOCs that may react with the S/S process. The type
and proportions of binding agents are adjusted to the specific
properties of the waste to achieve the desired physical and
chemical characteristics of the waste appropriate to the condi-
tions at the site based on bench-scale tests. Although ratios of
waste-to-binding agents are typically in the range of 10:1 to
2:1, ratios as low as 1:4 have been reported. However, projects
utilizing low waste-to-binder ratios have high costs and large
volume expansion.
Figures 1 and 2 depict generic elements of typical ex situ
and in situ S/S processes, respectively. Ex situ processing
involves: (1) excavation to remove the contaminated waste
from the subsurface; (2) classification to remove oversize de-
bris; (3) mixing; and (4) off-gas treatment In situ processing
has only two steps: (1) mixing; and (2) off-gas treatment
Both processes require a system for delivering water, waste,
and S/S agents in proper proportions and a mixing device (e.g.,
rotary drum paddle or auger). Ex situ processing requires a
system for delivering the treated waste to molds, surface
trenches, or subsurface injection. The need for off-gas treat-
ment using vapor collection and treatment modules is specific
to the S/S project
Process Residuals
Under normal operating conditions neither ex situ nor in
situ S/S technologies generate significant quantities of contami-
nated liquid or solid waste. Certain S/S projects require treat-
ment of the offgas. Prescreening collects debris and materials
too large for subsequent treatment
If the treated waste meets the specified cleanup levels, it
could be considered for reuse onsite as backfill or construction
material. In some instances, treated waste may have to be
disposed of in an approved landfill. Hazardous residuals from
some pretreatment technologies must be disposed of accord-
ing to appropriate procedures.
Engineering Bulletin: Solidification/Stabilization of Organic* and Inorganics
-------
Figure 1.
Generic Elements of a Typical Ex Sttu S/S Process
S/S Binding
Agent(s)
i
Mixing
(3)
t
-*
Off-Gas
Treatment
(optional)
(4)
-b. Stabilized/!
Water
Residuals
Media
Figure 2.
Generic Elements of a Typical In Sttu S/S Process
Water-
S/S Binding -
Agent(s)
Stabilized/Solidified
Media
Residuals
Site Requirements
The site must be prepared for the construction, operation,
maintenance, decontamination, and ultimate decommission-
ing of the equipment An area must be cleared for heavy
equipment access roads, automobile and truck parking lots,
material transfer stations, the S/S process equipment, set up
areas, decontamination areas, the electrical generator, equip-
ment sheds, storage tanks, sanitary and process wastewater
collection and treatment systems, workers' quarters, and ap-
proved disposal facilities (ft required). The size of the area
required for the process equipment depends on several factors,
including the type of S/S process involved, the required treat-
ment capacity of the system, and site characteristics, especially
soil topography and load-bearing capacity. A small mobile ex
situ unit could occupy a space as small as that taken up by two
standard flatbed trailers. An in situ system requires a larger area
to accommodate a drilling rig as well as a larger area for auger
decontamination.
Process, decontamination, transfer, and storage areas should
be constructed on impermeable pads with berms for spill reten-
tion and drains for the collection and treatment of stormwater
runoff. Stormwater storage and treatment capacity require-
ments will depend on the size of the bermed area and the local
climate. Standard 440V, three-phase electrical service is usually
needed. The quantity and quality of process water required for
pozzolanic S/S technologies are technology-specific.
S/S process quality control requires information on the
range of concentrations of contaminants and potential
interferants in waste batches awaiting treatment and on treated
product properties such as compressive strength, permeability,
teachability, and in some instances, contaminant toxicity.
Performance Data
Most of the data on S/S performance come from studies
conducted for EPA's Risk Reduction Engineering Laboratory
under the Superfund Innovative Technology Evaluation (SITE)
Program. Pilot scale demonstration studies available for review
during the preparation of this bulletin included: Soliditech, Inc.
at Morganville, New Jersey (petroleum hydrocarbons, PCBs,
other organic chemicals, and heavy metals); International Waste
Technologies (IWT) process using the Ceo-Con, Inc. deep-soil-
mixing equipment, at Hialeah, Florida (PCBs, VOCs); Chemfix
Technologies, Inc., at Clackamas, Oregon (PCBs, arsenic, heavy
metals); Im-Tech (formerly Hazcon) at Oouglassville, Pennsyl-
vania (oil and grease, heavy metals including lead, and low
levels of VOCs and PCBs); Silicate Technology Corporation
(STQ, at Sdma, California (arsenic, chromium, copper, penta-
chlorophenol and associated polychlorinated dibenzofurans and
dibenzo-p-dioxins). The performance of each technology was
evaluated in terms of ease of operation, processing capacity,
frequency of process outages, residuals management, cost, and
the characteristics of the treated product Such characteristics
Engineering Bulletin: Solidification/Stabilization of Organic* and Inorganics
-------
included weight, density, and volume changes; DCS and mois-
ture content of the treated product before and after freeze/
thaw and wet/dry weathering cycles; permeability (or
permissivity) to water; and teachability following curing and
after the weathering test cycles. Leachability was measured
using several different standard methods, including EPA's TCLP.
Table 4 summarizes the SUE performance data from these sites
[20] [24] [25] [26] [27] [28].
A full-scale S/S operation has been implemented at the
Northern Engraving Corporation (NEC) site in Sparta, Wiscon-
sin, a manufacturing facility which produces metal name plates
and dials for the automotive industry. The following informa-
tion on the site is taken from the remedial action report Four
areas at the site that have been identified as potential sources of
soil, groundwater, and surface water contamination are the
sludge lagoon, seepage pit, sludge dump site, and lagoon
drainage ditch. The sludge lagoon was contaminated primarily
with metal hydroxides consisting of nickel, copper, aluminum,
fluoride, iron, and cadmium. The drainage ditch which showed
elevated concentrations of copper, aluminum, fluoride, and
chromium, was used to convey effluent from the sludge lagoon
to a stormwater runoff ditch. The contaminated material in the
drainage ditch area and sludge dumpsite was then excavated
and transported into the sludge lagoon for stabilization with
the sludge present. The vendor, Ceo-Con, Inc., achieved stabi-
lization by the addition of hydrated lime to the sludge. Five
samples of the solidified sludge were collected for Extraction
Procedure (EP) toxicity leaching analyses. Their contaminant
concentrations (in mg/l) are as follows: Arsenic (<.01); Barium
(.35-1.04); Cadmium (<.005); Chromium (<.01); Lead(<2);
Mercury (<.001); Selenium (<.005); Silver (<.01); and Fluoride
(2.6 - 4.1). All extracts were not only below the EP toxicity
criteria but (with the exception of fluoride) met drinking water
standards as well.
Approximately three weeks later DCS tests on the solidified
waste were taken. Test results ranged from 2.4 to 10 psi, well
below the goal of 25 psi. One explanation for the low DCS
could be due to shear failure along the lenses of sandy material
and organic peat-like material present in the samples. It was
determined that it would not be practical to add additional
quantities of lime into the stabilized sludge matrix because of its
high solids content Therefore, the stabilized sludge matrix
capacity will be increased to support the clay cap by installing
an engineered subgrade for the cap system using a stabilization
fabric and aggregate prior to cap placement [29].
The Industrial Waste Control (IWQ Site in Fort Smith,
Arkansas, a closed and covered industrial landfill built in an
abandoned surface coal mine, has also implemented a full-scale
S/S system. Until 1978 painting wastes, solvents, industrial
process wastes, and metals were disposed at the site. The
primary contaminants of concern were methylene chloride,
ethylbenzene, toluene, xylene, trichloroethane, chromium, and
lead. Along with S/S of the onsite soils, other technologies used
were: excavation, slurry wall, french drains, and a landfill cover.
Soils were excavated in the contaminated region (Area Q and a
total of seven lifts were stabilized with flyash on mixing pads
previously formed. A day liner was then constructed in Area C
to serve as a leachate barrier. After the lifts passed the TCLP test
they were taken to Area C for in situ solidification. Portland
cement was added to solidify each lift and they obtained the
UCS goal of 125 psi. With the combination of the other tech-
nologies, the overall system appears to be functioning properly
[30].
Other Superfund sites where full scale S/S has been com-
pleted to date include Davie Landfill (82,158 yd3 of sludge
containing cyanide, sulfide, and lead treated with Type I Port-
land cement in 45 days) [31 ]; Pepper's Steel and Alloy (89,000
yd3 of soil containing lead, arsenic, and PCBs treated with
Portland cement and fly ash) [32]; and Sapp Battery and
Salvage (200,000 yd3 soil fines and washings containing lead
and mercury treated with Portland cement and fly ash in roughly
18 months) [33], all in Region 4; and Bio-Ecology, Inc. (about
20,000 yd3 of soils, sludge, and liquid waste containing heavy
metals, VOCs, and cyanide treated with cement kiln flue dust
alone or with lime) in Region 6 [34]. All sites required that the
waste meet the appropriate leaching test and UCS criteria. At
the Sapp Battery site, the waste also met a permeability crite-
rion of 1Q-4 cm/s [33]. Past remediation appraisals by the
responsible remedial project managers indicate the S/S tech-
nologies are performing as intended.
RCRA LDRs that require treatment of wastes based on
BOAT levels prior to land disposal may sometimes be deter-
mined to be Applicable or Relevant and Appropriate Require-
ments (ARARs) for CERCLA response actions. S/S can produce a
treated waste that meets treatment levels set by BOAT but may
not reach these treatment levels in all cases. The ability to meet
required treatment levels is dependent upon the specific waste
constituents and the waste matrix. In cases where S/S does not
meet these levels, it still may in certain situations be selected for
use at a site if a treatability variance establishing alternative
treatment levels is obtained. Treatability variances may be
justified for handling complex soil and debris matrices. The
following guides describe when and how to seek a treatability
variance for soil and debris: Superfund LOR Guide #6A, "Ob-
taining a Soil and Debris Treatability Variance for Remedial
Actions* (OSWER Directive 9347.3-06FS) [16], and Superfund
LDR Guide #68, "Obtaining a Soil and Debris Treatability Vari-
ance for Removal Actions" (OSWER Directive 9347.3-06BFS)
[17]. Another approach could be to use other treatment tech-
niques in conjunction with S/S to obtain desired treatment
levels.
Technology Status
In 1990,24 RODs identified S/S as the proposed remediation
technology [35]. To date only about a dozen Superfund sites
have proceeded through full-scale S/S implementation to the
operation and maintenance (O&M) phase, and many of those
were small pits, ponds, and lagoons. Some involved S/S for off-
site disposal in RCRA-permitted facilities. Table 5 summarizes
these sites where full scale S/S has been implemented under
CERCLA or RCRA [7, p. 3-4].
More than 75 percent of the vendors of S/S technologies
use cement-based or pozzolank mixtures [11, p. 2]. Organic
polymers have been added to various cement-based systems to
enhance performance with respect to one or more physical or
a
Engineering Bulletin: Soildificotion/Stobttlzation of Organics and Inorganics
-------
Table 4. Summary of SITE Performance Data
Site
Imperial Oil Co. /
Champion Chemical Co.
Morganville, N|
GE Electrical Servke Shop
Hialeah, FL
Portable Equipment
Salvage Co.
Clackamas, OR
Oouglasville
Douglasville, PA
Selma Pressure Treating
Wood Preserving Site
Selma, CA
Vendor Technology
Solidrtech: Urrichem reagent, water,
additives. Type II Portland cement
IWT-DMS/Geo-Con:
In situ injection of silicate additive
Chemfix: polysilkates and dry
calcium containing reagents
Imtech (Hazcon): Chtoranan™,
water and cement
Silkate Tech Corp.:
alumino-silicate compounds
Pretreatment
Bulk density: 1.14to 1.26 g/cm1
Permeability: Not determined
UCS: Not determined
Lead-TCLP Extract 0.46 mg/l
Bulk density:!. 55 g/ml
Permeability: 1.8x10 'cm/s
UCS:1.2to1.8Spsl
TCLP-Extractable (Pb, Cu, In):
12 to 880 mg/l
Hydraulic cond.(CSS-1 3):
2.4 xlO* to 2.7x10" cm/s
Bulk density: 2.0 to 2.6 g/cm1
Bulk density: 1.23 g/ml
Permeability: 0.57 cm/s
TCLP-Extractable Pb: 52.6 mg/l
Arsenic-TCLP: 1.06 to 3.33 ppm
Arsenic-Distilled Hfl TCLP: 0.73 to 1 .25 ppm
PCP-TWA: 1983 to 8317 ppm
Bulk density: 1 .42 to 1 .54 g/cm
Post Treatment
Bulk density: 1.43 to 1.68 g/cm1
Permeability: 8.9x10' to 4.5xW cm/s
UCS: 390 to 860 psi
Lead-TCLP extract: <0.05 to <0.20 mg/l
Bulk density: 1.88 g/ml
Permeability: 0.24x10 ' to 21x1 a' cm/s
UCS: 300 to 500 psi
TCLP-Extractable (Pb, Cu, Zn): 0.024 to 47 mg/l
Hydraulk cond. (CSS-14): 4.6x10' to 1.2x10* cm/s
Bulk density: 1 .6 to 2.0 g/cm1
USC (14, 21, 28 days): 1 31. 1 36, 143 psi
Immersion UCS (30, 60, 90 days): 1 77, 188, 204 psi
Bulk density (7, 28 days): 1 .95, 1 .99 g/ml
Permeability (7, 28 days): 1.6x10', 2.3x10* cm/s
TCLP-Extractable Pb (7, 28 days): 0.14. 0.05 mg/l
UCS (7,28 days): 1447,1 1 3 psi
Arsenic-TCLP: 0.086 to 0.875 ppm
Arsenic-Distilled H,0 TCLP: < 0.01 to 0.012 ppm
PCP-TWA: 14 to 158 ppm
Bulk density: 1 .57 to 1 .62 g/cm
Permeability: 0.8x1 07 to 1.7x1 a7 cm/s
UCS: 259 to 347 psi
I
o
I
UCS - Unconfined Compressive Strength
TCLP - Toxicity Characteristic Leaching Procedure
TWA-Total Waste Analysis
-------
Table 5. Summary of Full Scale S/S Sites
Site
Midwest, US Plating
Company
Unnamed
Marathon Steel,
Phoenix, A2
AtaikaReflnwy
Unnamed, Kentucky
NEReflnery "
Velsicol Chemical
Amoco WfoodWvec
Pepper Steel fc Alloy,
Miami, FL
Vkkery/Ohlp
Wood Treating,
Savannah, CA
Chem*efin«y,TX
API Sep. Sludge,
Puerto Rico
MetapJating, W|
Contaminant
Zn,Cc,GiN!
Cu, Cr, Ni
Pb/toBMOOppm
Pb, Cd
Vinyl chloride
EthyJene dichloride
Pestkides and organics (resins,
etc.) up to 45% organic
m/tdMt "' V''"'"
Oil saturated soil
Pb-IOOOppm
PCBs-200 ppm
As-1-200ppm
Waste**!' ••••••
Creosote wastes
Combined metals, sulfur, oil
sludge*,etc _ ';;U
API separator sludges
AWSOOppm
NI750 ppm
Cr-220ppm
€u~20QOppm
Physical Form
Sludge
Dry landfill
Sludges, variable
Slu<^-r?-vj,*m'
>J'<>! ^!S.
Soils
Sludges
Sludges
Binder
Portland cement, ;'.,
Portland cement
•••< 5-~' <;',-
Portland ccrmnt wxJ
proprfetnry tngcedtent
Portland cement and silicates
WWabd cement wrwr-t' -Iv'i
Portland cement and
proprietary ingredient
Portland cement and kiln dust,
proprietary Ingredient
Pouolank and proprietary
Ingredient
Kiln dust
Portland cement and
proprietary ingredient
Percentage Binder(s)
Added
20%
Varied 7-15%
(cement)
Varied 25*
Varied (cement 5-15%)
20%
50% cement
-4 % proprietary
Treatment (batch/
continuous In Situ)
8at «v£ «v
-------
chemical characteristics, but only mixed results have been
achieved. For example, tests of standardized wastes treated in
a standardized fashion using acrylonitrile, vinyl ester, polymer
cement, and water-based epoxy yielded mixed results. Vinyl
and plastic cement products achieved superior DCS and leach-
ability to cement-only and cement-fly ash S/S, while the acry-
lonitrile and epoxy polymers reduced DCS and increased leach-
able TOC, in several instances by two or three orders of
magnitude [36, p. 156].
The estimated cost of treating waste with S/S ranges from
$50 to 250 per ton (1992 dollars). Costs are highly variable
due to variations in site, soil, and contaminant characteristics
that affect the performance of the S/S processes evaluated.
Economies of scale likely to be achieved in full-scale operations
are not reflected in pilot-scale data.
EPA Contact
Technology-specific questions regarding S/S may be di-
rected to:
Cariton C. Wiles or Patricia M. Erickson
U.S. Environmental Protection Agency
Municipal Solid Waste and Residuals
Management Branch
Risk Reduction Engineering Laboratory
5955 Center Hill Road
Cincinnati, OH 45224
Telephone: (513) 569-7795 or (513) 569-7884
Acknowledgments
This bulletin was prepared for the US Environmental Pro-
tection Agency, Office of Research and Development (ORD),
Risk Reduction Engineering Laboratory (RREL), Cincinnati, Ohio,
by Science Applications International Corporation (SAIQ under
contract No. 68-C8-0062 (WA 2-22). Mr. Eugene Harris served
as the EPA Technical Project Manager. Mr. Gary Baker was
SAIC's Work Assignment Manager. This bulletin was written by
Mr. Larry Fink and Mr. George Wahl of SAIC. The authors are
especially grateful to Mr. Cariton Wiles and Mr. Edward Bates of
EPA, RREL and Mr. Edwin Barth of EPA, CERI, who have contrib-
uted significantly by serving as technical consultants during the
development of this document.
The following other EPA and contractor personnel have
contributed their time and comments by participating in the
expert review meetings or peer reviews of the document
Dr. Paul Bishop
Dr. Jeffrey Means
Ms. Mary Boyer
Mr. Cecil Cross . _.^
Ms. Margaret Groeber SAIC-Cncinnati
Mr. Eric Saylor SAIC-Gncinnati
University of Cincinnati
Battelle
SAIC-Raleigh
SAIC-Raleigh
Engineering Bulletin: Solidification/Stabilization of Organic* and Inorganics
U
-------
REFERENCES
1. Conner, j.R. Chemical Fixation and Solidification of
Hazardous Wastes, Van Nostrand Reinhold, New York,
1990.
2. Technical Resources Document on Solidification/Stabiliza-
tion and its Application to Waste Materials (Draft),
Contract No. 68-CO-0003, Office of Research and
Development, U.S. Environmental Protection Agency,
Cincinnati, Ohio, 1991.
3. Guidance on Key Terms. Office of Solid Waste and
Emergency Response. U.S. Environmental Protection
Agency. Directive No. 9200.5-220, Washington, D.C.,
1991.
4. Wiles, C.C. Solidification and Stabilization Technology. In:
Standard Handbook of Hazardous Waste Treatment and
Disposal, H.M. Freeman, Ed., McCraw Hill, New York,
1989.
5. jasperse, B.H. Soil Mixing, Hazmat World, November
1989.
6. Handbook for Stabilization/Solidification of Hazardous
Waste. EPA/540/2-86/001, U.S. Environmental Protection
Agency, Cincinnati, Ohio, June 1986.
7. Stabilization/Solidification of CERCLA and RCRA Wastes;
Physical Tests, Chemical Testing Procedures, Technology,
and Field Activities. EPA/625/6-89/022, U.S. Environmen-
tal Protection Agency, Gncinnati, Ohio, May 1990.
8. Wiles, C.C. and E. Barth. Solidification/Stabilization: Is It
Always Appropriate? Pre-Publication Draft, American
Society of Testing and Materials, Philadelphia, Pennsylva-
nia, December 1990.
9. Superfund Treatability Clearinghouse Abstracts. EPA/540/
2-89/001, U.S. Environmental Protection Agency,
Washington, D.C., August 1989.
10. Kasten, j.L, H.W. Codbee, T.M. Cilliam, and S.C.
Osbome, 1989. Round I Phase I Waste Immobilization
Technology Evaluation Subtask of the Low-Level Waste
Disposal Development and Demonstration Program,
Prepared by Oak Ridge National Laboratories, Martin
Marietta Energy Systems, Inc., Oak Ridge, Tennessee, for
Office of Defense and Transportation Management under
Contract DE-AC05-840R21400, May 1989.
11. |ACA Corporation. Critical Characteristics and Properties
of Hazardous Solidification/Stabilization. Prepared for
Water Engineering Research Laboratory, Office of
Research and Development, U.S. Environmental Protec-
tion Agency, Gncinnati, Ohio. Contract No. 68-03-3186,
1985.
12. Bricka, R.M., and LW. Jones. An Evaluation of Factors
Affecting the Solidification/Stabilization of Heavy Metal
Sludge, Waterways Experimental Station, U.S. Army
Corps of Engineers, vlcksburg, Mississippi, 1989.
13. Fate of Polychlorinated Biphenyts (PCBs) in Soil Following
Stabilization with Quicklime, EPA/600/2-91/052, U.S.
Environmental Protection Agency, Cincinnati, Ohio,
September 1991.
14. Convery, J. Status Report on the Interaction of PCB's and
Quicklime, Risk Reduction Engineering Laboratory, Office
of Research and Development, U.S. Environmental
Protection Agency, Gncinnati, Ohio, June 1991.
15. Stinson, MX EPA SITE Demonstration of the Interna-
tional Waste Technologies/Ceo-Con In Situ Stabilization/
Solidification Process. Air and Waste Management J.,
40(11): 1569-1576.
16. Superfund LDR Guide #6A (2nd edition), "Obtaining a
Soil and Debris Treatability Variance for Removal Ac-
tions', OSWER. Directive 9347.3-06FS, September 1990.
17. Superfund LDR Guide #6B, "Obtaining a Soil and Debris
Treatability Variance for Removal Actions', OSWER
Directive 9347.3-06BFS, September 1990.
18. Chasalani, D., F.K. Cartiedge, H.C. Eaton, M.E.
Tittiebaum, and M.B. Walsh. The Effects of Ethytene
Glycol on a Cement-Based Solidification Process. Hazard-
ous Waste and Hazardous Materials. 3(2): 167-173,
1986.
19. Handbook of Remedial Action at Waste Disposal Sites.
EPA/625/6-85/006, U.S. Environmental Protection
Agency, Gncinnati, Ohio, June 1985.
20. Technology Evaluation Report SITE Program Demonstra-
tion Test Soliditech, Inc Solidification/Stabilization
Process, Volume I. EPA/540/5-89/005a, U.S. Environ-
mental Protection Agency, Gncinnati, Ohio, February
1990.
21. Kirk-Othmer. Cement. Encyclopedia of Chemical
Technology, 3rd Ed., John Wiley and Sons, New York:
163-193,1981.
22. Soundararajan, R., and ).|. Gibbons, Hazards in the
Quicklime Stabilization of Hazardous Waste. Unpublished
paper delivered at the Gulf Coast Hazardous Substances
Research Symposium, February 1990.
23. Weitzman, L, LR. Harnd., and S. Cadmus. Volatile
Emissions From Stabilized Waste, Prepared By Acurex
Corporation Under Contract No. 68-02-3993 (32, 37) for
the Risk Reduction Engineering Laboratory, Office of
Research and Development, U.S. Environmental Protec-
tion Agency, Gncinnati, Ohio, May 1989.
72
Engineering Bulletin: SoUdfflcation/StabBlzaHon of Organic* and Inorganics
-------
24. Technology Evaluation Report SITE Program Demonstra-
tion Test International Waste Technologies In Situ
Stabilization/Solidification - Hiateh, Florida, Volume I.
EPA/540/5-89/004a, U.S. Environmental Protection
Agency, Cincinnati, Ohio, June 1989.
25. Technology Evaluation Report Chemfix Technologies,
Inc Solidification/Stabilization Process • Clackamas,
Oregon, Volume I. EPA/540/5-89/011 a, U.S. Environ-
mental Protection Agency, Cincinnati, Ohio, September
1990.
26. Technology Evaluation Report SITE Program Demonstra-
tion Test HAZCON Solidification, Douglassville, Pennsyl-
vania, Volume I. EPA/540/5-89/001 a, U.S. Environmen-
tal Protection Agency, Washington, D.C., February 1989.
27. Bates, E.R., P.V. Dean, and I. Klich, Chemical Stabilization
of Mixed Organic and Metal Compounds: EPA SITE
Program Demonstration of the Silicate Technology
Corporation Process, journal of the Air & Waste Manage-
ment Association. 42(5): 724-728,1992.
28. Applications Analysis Report Silicate Technology
Corporation. Solidification/Stabilization Technology for
Organic and Inorganic Contaminants in Soils, EPA/540/
AR-92/010, U.S. Environmental Protection Agency.
Washington, D.C., December 1992.
29. Eder Associates Consulting Engineers, P.C. Northern
Engraving Corporation Site Remedial Action Report
Sparta, Wisconsin, 1989.
30. Remedial Construction Report Industrial Waste Control
Site. Fort Smith, Arkansas. U.S. Environmental Protection
Agency, 1991.
31. lackson, R. RPM, Davie Landfill, Florida. Personal
Communication. Region 4, U.S. Environmental Protection
Agency, Atlanta, Georgia, August 1991.
32. Scott, D. RPM, Pepper's Steel and Alloy. Personal
Communication. Region 4, U.S. Environmental Protection
Agency, Atlanta, Georgia, October 1991.
33. Berry, M. RPM, Sapp Battery and Salvage, Florida.
Personal Communication. Region 4, U.S. Environmental
Protection Agency, Atlanta, Georgia, August 1991.
34. Pryor, C. RPM, Bio-Ecology Systems, Texas. Personal
Communication. Region 6, U.S. Environmental Protection
Agency, Dallas, Texas, August 1991.
35. Rod Annual Report FY1990. EPA/540/8-91/067, U.S.
Environmental Protection Agency, Washington D.C., July,
1991.
36. Kytes, J.H., K.C. Malinowski, j.S. Leithner, and T.F.
Stanczyk. The Effect of Volatile Organic Compounds on
the Ability of Solidification/Stabilization Technologies To
Attentuate Mobile Pollutants. In: Proceedings of the
National Conference on Hazardous Waste and Hazardous
Materials. Hazardous Materials Control Research Institute,
Silver Springs, MD, March 16-18, 1987.
Engineering Bulletin: Solidification/Stabilization of Organic* and Inorganics
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Environmental Protection^!"*-"^' Remedial Response
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Supartund-
EPA/540/S-94/504'
October 1994
Engineering Bulletin
In Situ Vitrification
• *"•• - • . -.-.'.
Treatment a
Purpose
Section 121(t>) of the Comprehensive Environmental Re-
sponse, Compensation, and Liability Act (CERCLA) mandates
the Environmental Protection Agency (EPA) to select remedies
that "utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the maxi-
mum extent practicable" and to prefer remedial actions in
which treatment "permanently and significantly reduces the
volume, toxicity, or mobility of hazardous substances, pollut-
ants and contaminants as a principal element." The Engineer-
ing Bulletins are a series of documents that summarize the latest
information available on selected treatment and site remedia-
tion technologies and related issues. They provide summaries
of and references for the latest information to help remedial
project managers, on-scene coordinators, contractors, and
other site cleanup managers understand the type of data and
site characteristics needed to evaluate a technology for poten-
tial applicability to their Supeiiund or other hazardous waste
site. Those documents that describe individual treatment
technologies focus on remedial investigation scoping needs.
Addenda will be issued periodically to update the original
bulletins.
Abstract
In situ vitrification (ISV) uses electrical power to heat and
melt soil, sludge, mine tailings, buried wastes, and sediments
contaminated with organic, inorganic, and metal-bearing haz-
ardous wastes. The molten material cools to form a hard,
monolithic, chemically inert, stable glass and crystalline prod-
uct that incorporates and immobilizes the thermally stable
inorganic compounds and heavy metals in the hazardous
•waste. The slag product material is glass-like with very low
leaching characteristics.
Organic wastes are initially vaporized or pyrolyzed by the
process. These contaminants migrate to the surface where the
majority are then burned within a hood covering the treatment
area; the remainder are treated in an ofigas treatment system.
ISV uses a square array of four electrodes that are inserted
into the surface of the ground. Electrical power is applied to the
electrodes which, through a starter path of graphite and glass
frit, establish an electric current in the soil. The electric current
generates heat and melts the starter path and the soil; typical
soil melt temperature is 2,900°F to 3,600°F. An electrode feed
system (EPS) drives the electrodes in the soil as the molten mass
continues to grow downward and outward until the melt zone
reaches the desired depth and width. The process is repeated
in square arrays until the desired volume of soil has been
vitrified. The process can typically treat up to 1,000 tons of
material in one melt setting.
ISV technology has been under development and testing
since 1980 [1, p. 1]*. ISV was developed originally for possible
application to soils contaminated with radioactive materials. In
this application, trans-uranium radionuclides are incorporated
in the vitrified mass. At this time there is only one vendor of
commercially available in situ vitrification systems. The
technology description, status, and performance data are
quoted from the published work of this vendor.
ISV is the proposed remediation technology at eight sites,
six of which are EPA Superfund sites [2] [3]. Full-scale units have
been constructed. Even so, the technology should be consid-
ered emerging in its full-scale application to Superfund sites.
EPS mechanisms have recently been developed for pilot- and
full-scale systems. This bulletin provides information on the
technology applicability, limitations, the types of residuals
produced, the latest performance data, site requirements, the
status of the technology, and sources for further information.
Site-specific treatability studies are the best means of
establishing the applicability and projecting the likely perfor-
mance of an ISV system. Determination of whether ISV is the
best treatment alternative will be based on multiple site-specific
factors, cost, and effectiveness. The EPA Contact indicated at
the end of this bulletin can assist in the location of other
contacts and sources of information necessary for such treat-
ability studies.
Technology Applicability
ISV has been reported to be effective in treating a large
variety of organic and inorganic wastes based on the results of
engineering- and pilot-scale tests. The technology also has
* [reference number, page number]
Printed on Recycled Paper
-------
proven effectiveness in treating radioactive wastes based on the
results of full-scale tests. Radioactive wastes and sludges,
contaminated soils and sediments, incinerator ashes, industrial
wastes and sludges, medical wastes, mine tailings, and
underground storage tank waste can all potentially be vitrified
[4, p. 4-1].
Organic contaminants at concentrations of 5 to 10 percent
by weight and inorganic contaminants at concentrations of 5
to 15 percent by weight are generally acceptable for ISV
treatment [5, p. 13]. The effectiveness of the ISV technology on
treating various contaminants in soil, sludge, and sediments is
given in Table 1. Examples of constituents within contaminant
groups are provided in the Technology Screening Guide for
Treatment of CERCLA Soils and Sludges' [6]. Table 1 is based
on current available information or professional judgment
where no information was available. The proven effectiveness
of the technology for a particular site or waste does not ensure
that it will be effective at all sites or that the treatment levels
achieved will be acceptable at other sites. For the ratings used
for this table, demonstrated effectiveness means that at some
scale, treatability tests have shown that the technology was
effective for that particular contaminant and matrix. The
ratings of potential effectiveness or no expected effectiveness
are both based upon expert opinion. Where potential effective-
ness is indicated, the technology is believed capaote ci Access-
fully treating the contaminant group in a particular matrix. The
technology is expected to work for all contaminant groups
listed.
ISV processing requires that sufficient glass-forming ma-
terials (e.g., silicon and aluminum oxides) be present within the
waste materials to form and support a high-temperature melt.
To form a melt, sufficient (typically 2 to 5 percent) monovalent
alkali cations (e.g., sodium and potassium) must be present to
provide the degree of electrical conductivity needed for the
process to operate efficiently. If the natural material does not
meet this requirement, fluxing materials such as sodium car-
bonate can be added to the base material. Typically, these
conditions are met by most soils, sediments, tailings, and
process sludges.
Differences in soil characteristics such as permeability and
density generally do not affect overall chemical composition of
the soil or the ability to use ISV. In many site locations, the soil
profile may be stratified and present nonuniform characteristics
that can affect the melt rate and dimensions of the vitrified
mass. Before applying the ISV technology, soil stratification
must be defined so that it may be factored into the remedial
design.
Table 1
Effectiveness of ISV on General Contaminant
Groups for Soil, Sludges, and Sediments
Contaminant Croups
_u
"c
0
Ot
O
c
O
1
V
u
O
«
Halogenated volatiles
Halogenated semivolatiles
Nonhalogenated volatiles
Nonhalogenated semivolatiles
Polychlorinated biphenyls (PCBs)
Pesticides (halogenated)
Dioxins/Furans
Organic cyanides
Organic corrosives
Volatile metals
Nonvolatile metals
Asbestos
Radioactive materials
Inorganic corrosives
Inorganic cyanides
Oxidizers
Reducers
Effectiveness
Soil Sludge Sediments
T
T
T
T
T
T
T
T
T
•
T
T
T
•
•
T
T
T
T
T
T
T
T
T
T
•
V
T
T
T
•
•
T
T
T
T
T
T
• Demonstrated Effectiveness: Successful treatability test at
some scale has been completed
T Potential Effectiveness: Expert opinion that technology will
work
D No Expected Effectiveness: Expert opinion that technology
will not work
Limitations
The ISV process can treat soils saturated with water;
however, additional power is used to dry the soil prior to
melting and may increase the cost of remediation by 10
percent. ISV is more economical to implement when the soil to
be vitrified has a low moisture content. Progression of a melt
into saturated soil enclosed in a container can result in a
gaseous steam release that can cause the molten glass to
spatter.
When treating a contaminated zone in an aquifer, it may
be necessary to lower the water table below the zone of
contamination in order to vitrify to the desired depth. Alterna-
tively, a hydraulic barrier (e.g., slurry wall) could be placed
upstream of the contamination to divert the aquifer flow
around the treatment zone. Treatment in a water-saturated
zone may result in movement of some of the contaminants
from the treatment zone to surrounding areas, thereby reduc-
ing the amount of contaminants being destroyed, immobi-
lized, or removed.
The maximum ISV depth obtainable is influenced by
several factors, including spacing between electees, amount
of power available, variations in soil composition and gradation
between different strata, depth to groundwater, soil perme-
ability within an aquifer, surface heat loss during ISV, and waste
and soil density. To date, treatment depths of only 19 feet have
been demonstrated [4, p. 7-6).
The presence of large inclusions in the area to be treated
can limit the use of the ISV process. Inclusions are highly
concentrated contaminant layers, void volumes, containers,
metal scrap, general refuse, demolition debris, rock, or other
heterogeneous materials within the treatment volume. Figure |
Engineering Bulletin: In Situ Vitrification Treatment
-------
1 gives limits for inclusions within the treatment volume [7, p.
17]. If massive void spaces exist, a large subsidence could result
in a very short time period. These problems, as well as those
caused by other large inclusions, may be detected by ground
penetrometry or other geologic investigations. Some inclu-
sions such as void volumes, containers, and solid combustible
refuse can potentially generate gases. However, the oversized
hooding is intended to control and mitigate any release. If large
volumes of offgases are generated during a short time period,
the offgas treatment system may overload. Vitrification of
flammable or explosive objects can result in spattering of the
molten glass. Underground storage tanks can be treated only
if they are filled with soil prior to the vitrification process.
Sampling and analysis of the glass matrix produced by ISV
is difficult and must be carefully planned prior to conducting a
treatability study or site remediation. Current EPA digestion
methods for metal analyses are not designed to dissolve the
glass matrix. The metal concentration measured by a standard
nitric/hydrochloric acid digestion (SW-846, Method 3050) will
likely be highly dependent on the particle size of the material
prior to digestion. The digestion specified will not dissolve glass
but will leach some metals from the exposed surfaces. Closure
of mass balance for the system, therefore, can often be incom-
plete. However, a recently developed digestion method using
hydrofluoric acid with microwave digestion has been known to
improve metal analysis for this type of matrix.
Technology Description
Several methods and configurations exist for the applica-
tion of ISV. At a site that has only a relatively shallow layer of
contamination, the contaminated layer may be excavated and
transported to a pit where the vitrification will take place. At
other sites wnere the contamination is much deeper, thermal
barriers could be placed along the site to be vitrified and
prevent the movement of heat and glass into adjacent areas.
This will force the heat energy downward and melt depths will
be increased.
This bulletin describes the more conventional approach to
using ISV; a checkerboard pattern of melts is used to encapsu-
late the waste and control the potential for lateral migration.
The holes in the checkerboard are then vitrified to complete the
remediation of the site.
Figure 2 shows a typical ISV equipment layout. ISV uses a
square array of electrodes up to 18 feet apart, which is inserted
to a depth of 1 to 5 feet and potentially can treat down to a
depth of 20 feet to remediate a contaminated area. A full-scale
system can remediate at a rate of 3 to 5 ton? per hour [4, p. 3-
6] until a maximum mass of 800 to 1,000 tons has been treated.
Since soil is not electrically conductive once the moisture has
been driven off, a conductive mixture of flaked graphite and
glass frit is placed between the electrodes to act as a starter
path, as shown in Figure 3. Power is supplied to the electrodes,
which establishes an electrical current in the starter path. The
resultant power heats the starter path and surrounding soil up
to 3,600°F, which is well above the melting temperature of
typical soils (2,000CF to 2,600°F). The graphite starter path
eventually is consumed by oxidation and the current is trans-
ferred to the soil which is electrically conductive in the molten
state. A typical downward growth rate is 1 to 2 inches per hour.
The thermal gradient surrounding the melt is typically 300°F to
480°F per inch. As the vitrified zone grows, it incorporates
metals and either vaporizes or pyrolizes organic contaminants.
The pyrolyzed products migrate to the surface of the vitrified
zone, where they may oxidize in the presence of oxygen. A.
hood placed over the processing area is used to collect combus-
Flgure 1
General Limits for Inclusion Within Volume to Be Treated
Figure 2
ISV Equipment System
Electrode*
Void
Volume*
(inflviOuaJ
<1SOcu-ft)
Rubbto
(10-20 wfli)
, Combustible
f. Sows
(5-10*1%)
Combustible
Packages
(indnnoual
OOcu-n)
Continuous Metal
(<90* ^stance
enctrooes)
Of*-Ga*Hood
Controlled Air Input
Condttonlnf
Ali
Utility or DtoMt.
Genersud
Po
G*» Cleanup
SyitMn
1
Glycol
- Cooling
Clean Emission*
Engineering Bulletin: In Situ Vitrification Treatment
-------
Figure 3
Stag** of ISV Processing
Graphite and Glass
Fm Stanar Path
Electrodes to
Desired Depth
Subsidence
Contaminated
Soil Region
\
Backfill Over
Completed
Monoiith
Natural Soil
7
Vitrified Monolith
tion gases, which are treated in an offgas treatment system.
As the melt grows downward and outward, power is
maintained at sufficient levels to overcome the heat losses to
the hood and surrounding soil. Generally, the melt grows
outward to form a melt width approximately 50 percent wider
than the electrode spacing. This growth varies as a function of
electrode spacing and melt depth. The molten zone is roughly
a square with slightly rounded comers, a shape that reflects the
higher power density around the electrodes. As the melt grows
in size, the electrical resistance of the melt decreases; thus, the
ratio between the voltage and the current must be adjusted
periodically to maintain operation at an acceptable power
level.
The EPS, now an integral part of all operations, enhances
the ability of ISV to treat soils containing high concentrations of
metal. In EFS operations, the electrodes are independently fed
to the molten soil as the melt proceeds downward instead of
being placed in the soil prior to the startup of the test The
system improves processing control at sites with high concen-
trations of metal. For example, upon encountering a full or
partial electrical short, the affected electrodes are simply raised
and held above the molten metal pool at the bottom of the
melt. During this time, the melt continues to grow downward.
The electrodes can then be reinserted into the melt to their
original depth and resume electrode feeding operations. These
advances nave been incorporated into the pilot- and the full-
scale ISV systems (8J.
The treatment area is covered by a newly designed octag-
onal-shaped offgas collection hood with a maximum distance
of 60 feet between the sides. The hood has three manual
viewing ports and provision for video monitoring or recording.
The hood is connected to an offgas treatment trailer and a
backup offgas treatment system. During the process, the
off gases are drawn by a 1,850 standard cubic feet per minute
(scfm) blower into the trailer. Flow of air through the hood is
controlled to maintain a vacuum of 0.5 to 2.0 inches H2O on the
system. The offgas temperatures are typically 210°F to 750°F
when they enter the treatment system. The gases are then
treated by quenching, scrubbing, mist-elimination, heating,
paniculate filtration, and activated carbon adsorption. The
backup offgas treatment system is used in the event of a power
outage and is powered by a diesel generator. The backup
system is designed to treat gases that may evolve from the melt
until power is restored to the process and electrodes [9J.
Process Residuals
The main process residual produced during operation of
the ISV technology is the vitrified soil itself. The vitrified
monolith is left in place after treatment due to its nonhazardous
nature. The volume of the ISV product formed generally is 20
to 45 percent less than the initial volume treated. Because of
the volume reduction during processing, it is covered with
clean backfill. It is possible, however, to excavate and remove
the vitrified soil in smaller pieces if onsite disposal is not
acceptable at a given site.
Typically, the residual product from soil applications has
a compressive strength approximately 5 to 20 times greater
and a tensile strength approximately 7 to 11 times greater than
unreinforced concrete [4, p. 5-3]. It is usually not affected by
either wet/dry or freeze/thaw cycling [10, p. 3]. Existing data
indicate that the vitrified mass is devoid of residual organic* and
passes EPA'sToxicity Characteristic Leaching Procedure (TCLP)
test criteria for priority pollutant metals. The ISV residual also
has been found to have acceptable biotoxicity relative to near-
surface life forms [11, p. 79]. The clean backfill can be used to
revegetate the site or other end uses.
After processing for a period of time, the scrubber water,
filters, and activated carbon may contain sufficient contami-
nants to warrant treatment or disposal. Typical treatment
includes passing the contaminated scrubber water through a
filter, settling chamber, and activated carbon, then either
reusing the water or discharging it into a sanitary sewer. The
activated carbon, filter, and the solids from the settling cham-
ber can then be placed in an ISV setting for vitrification. In this
way, the destruction/chemical incorporation of contaminants
Engineering Bulletin: In Situ Vitrification Treatment
-------
collected in the offgas treatment system is maximized. Only
residuals resulting from the last setting at a site must be treated
and disposed of by means other than ISV.
Site Requirements
The components of the ISV system are contained in three
transportable trailers: an offgas and process control trailer; a
support trailer; and an electrical trailer. The trailers are mounted
on wheels sufficient for transportation to and over a compacted
ground surface [12, p. 307].
The site must be prepared for the mobilization, operation,
maintenance, and demobilization of the equipment An area
must be cleared for heavy equipment access roads, automobile
and truck parking lots, ISV equipment, setup areas, electrical
generator, equipment sheds, and workers' quarters.
The field-scale ISV equipment system requires three-phase
electric power at either 12,500 or 13,800 volts, which is usually
taken from a utility distribution system [13, p. 2]. At startup the
technology requires high voltage (up to 4,000 volts) to over-
come the resistance of the soil, and a current of approximately
400 amps. The soil resistance decreases as the melt progresses,
so that by the end of the process, the voltage decreases to
approximately 400 volts and the current increases up to
approximately 4,000 amps [4, p. 3-6]. Alternatively, the power
may be generated onsite by means of a diesel generator.
Typical applications require 800 kilowatt hour/ton (kWh/ton)
to1,OOOkWh/ton.
Spent activated carbon, scrubber water, or other process
waste materials may be hazardous, and the handling of these
materials requires that a site safety plan be developed to
provide for personnel protection and special handling mea-
sures. Storage should be provided to hold these wastes until
they have been tested to determine their acceptability for
disposal, release, or recycling to subsequent ISV melts. Storage
capacity will depend on the waste volume generated.
Site activities such as clearing vegetation, removing over-
burden, and acquiring backfill material are often necessary.
These activities are generally advantageous from a financial
point of view. For example, the cost of removal of the
top portion of clean soil would generally be much less than
the cost for labor and energy to vitrify the same volume of soil
[4, p. 9-6].
Performance Data
Performance data presented in this bulletin should not be
considered directly applicable to other Superfund sites. A
number of variables such as the specific mix and distribution of
contaminants affect system performance. A thorough charac-
terization of the site and a well-designed and conducted
treatability study are highly recommended.
The performance data currently available are from the
process developer. ISV has been developed through four scales
of equipment; 1) bench (5 to 20 pounds); 2) engineering (50
to 2,000 pounds); 3) pilot (10 to 50 tons); and 4) full (500 to
1,000 tons). The values in parentheses are typical masses of
vitrified products resulting from a single setting at the various
scales. Several tests have been performed at each scale and on
a variety of contaminated media.
An engineering-scale test was performed on loamy-clay
soil containing 500 parts per million (ppm) of PCBs. Figure 4
gives the final concentrations of PCBs (in ppm) in and around
the vitrified block upon completion of the test [13, p. 4-3). This
figure indicates that migration of PCBs outiide the vitrified
block is not a significant concern. Data from offgas emissions
and soil container smears accounted for 0.05 percent by weight
of the initial PCB quantity, which corresponds to a greater than
99.9 percent destruction efficiency (DE) for the ISV process.
This DE does not include the removal efficiency of the offgas
treatment system. Activated carbon has a 99.9 percent effi-
ciency and can remove any of these offgas emissions effectively.
Overall, the destruction removal efficiency (DRE) range for the
combined ISV and offgas system is between 6 and 9 nines
which is greater than the 6 nines DRE required by 40 CFR
761.70 for PCB incinerators. Analysis of the offgas also indi-
cated the presence of small quantities of polychlonnated
Figure 4
Vitrified Block and Surrounding Soil Sample
Positions and PCB Concentrations
OKXX
Inot
Of
10
15
20
25
30
35
40 -
123
<0.004J
Suosdenoe
C«vty v
0.005
I 043 /
\--c-3e1
> n io/.
0.19/
India) PCB
Sol Position
0.08 O.OOfi
-------
dibenzo-p-dioxins (PCDDs) and polychkxinated dibenzofurans
(PCDFs). However, the levels reported (0.1 ug/L and 0.4 ^ig/
L, respectively) can be removed by the offgas treatment system.
An engineering-scale test on PCB-contaminated sediments
from New Bedford Harbor [4, p. 4-2] gave a similar DE (99.9999
percent) for the ISV process before additional treatment by the
offgas treatment system. During feasibility testing of PCB-
contaminated soil from a Spokane, Washington site, a DE
greater than 99.993 percent and a DRE greater than 99.99999
percent were obtained [14]. During engineering-scale testing
of vitrification of simulated wastes from the Hanford Engineer-
ing Development Laboratory, a DRE of greater than 99.99
percent was obtained for a variety of organic contaminants
[15].
An engineering-scale test was performed on Idaho Na-
tional Engineering Laboratory spiked soil at the Pacific North-
west Laboratory. The soil was spiked with eight heavy metals
(Ag, As, Ba, Cd, Cr, Hg, Pb, and Se) to 0.02 percent by weight
except for lead which was spiked at 0.2 percent by weight [16].
The test results for metals concentrations in the leach extract
and maximum concentration limits established by EPA are
given in Table 2.
Feasibility testing was conducted using the bench-scale
ISV equipment to treat a sample of soil from the old Jacksonville,
Arkansas water treatment plant [17]. This soil was contaminat-
ed with 2,3,7,8-tetrachlorodibenzo-p-dioxin and placed in a 5-
gallon can with a Pyrex-plate lid. Analytical results did not
detect any dioxin or furan in the vitrified material or in the
offgas. Based on analytical detection limits, the DE was greater
than 99.995 percent prior to entry into the offgas treatment
system.
Ten thousand kilograms of an industrial sludge heavily
Table 2
TCLP Extract Metal Concentrations
Idaho National Engineering Lab Soils
Metal
Arsenic
Barium
Cadmium
Chromium
Lead
Mercury
Selenium
Silver
Maximum
Allowable
Leachatc
Concentration
(mg/L)
5.0
100.0
1.0
5.0
5.0
0.2
1.0
5.0
Contaminated
Soil
Concentration
(mg/kg)
200
200
200
200
2000
200
200
200
Vitrified Product
Leachatc
Concentration
(mg/L)
<0.168
0.229
0.0098
0.01 78
0.636
<0.0001
0.098
<0.023
laden with zirconia and lime was vitrified successfully by the
pilot-scale ISV process. The sludge contained 55 to 70 percent
moisture by weight. The volume was observed to be reduced
significantly (more than one-third of original volume) after the
testing [ 18, p. 29]. Analysis of the offgas and the scrubber water
showed that the melt retained between 98 and 99 percent of
the fluorides, chlorides, and sulfates. Analysis indicated that the
destruction of organic carbon was good and that ISV was
effective in promoting nitrogen oxide (NO,) destruction. This
result minimizes the concern for environmental impact.
Soil from a fire training pit contaminated with fuel oils and
heavy metals was bench-scale tested at the Arnold Engineering
Development Center in Tennessee [19]. Results of initial testing
and analyses of the soil indicated that an electrically-conduct-
ing fluxing agent (such as sodium carbonate) with a lower
melting point was required as an addition to the soil for ISV
processing to work effectively. The onsite pilot-scale process
achieved a high destruction of organics (greater than 98
percent) and high retention of inorganics in the melt. Leach
testing using Extraction Procedure Toxicity (EP-Tox) and TCLP
tests showed that all metals of concern were below maximum
permissible limits. The tests indicate that the fluxing agent
should be distributed throughout the entire vitrification depth
for optimum operation.
Technology Status
The only vendor supplying commercial systems for in situ
vitrification of hazardous wastes is Ceosafe Corporation. Ceosafe
is under a sublicense from the process developer, Battelle
Memorial Institute. Four scales of units are in operation ranging
from bench-scale to full-scale.
To date, only bench-, engineering-, and pilot-scale test
results are available on in situ vitrification of hazardous wastes.
Full-scale tests have been completed only on radioactive wastes.
Table 3 indicates several sites where ISV has been selected as the
remedial action [2].
In April 1991, a fire involving the full-scale collection ISV
hooding occurred at the Ceosafe Hanford, Washington test
site. The vendor was testing a new, lighter hooding material.
The hooding caught fire during the test when a spattering of
the melt occurred. For a period of time after the incident,
Ceosafe suspended full-scale field operations. During this time,
Ceosafe completed analytical, modeling, and engineering-
scale testing to allow confident design; defined necessary
process revisions; finalized design and fabrication of a new
metal offgas collection hood; and performed additional opera-
tional acceptance testing to demonstrate the capabilities of the
equipment and operational procedures [20]. The new offgas
collection hood design is composed entirely of metal rather
than high-temperature fabric, which was previously used. The
new design is heavier than the fabric hood, but is capable of
being transported by the same equipment.
Cost estimates for this technology range from J300 to
S650 per ton of contaminated soil treated. The most significant
factor influencing cost is the depth of the soil to be treated. High
Engineering Bulletin: In Situ Vitrification Treatment
-------
T«bl« 3
Sctoctad Slt«t Specifying ISV as the R«m«dl«l Action
Site
Mau,Volume to be Treated Primary Contaminants
Status
Parsons Chemical
Ionia City Landfill
Rocky Mountain Arsenal
Wasatch Chemical
Soil: 2,000 cubic yards (yd})
Soil with debris: 5,000yd3
(15 feet deep)
Soil: 4,600 yd3 (10 feet deep)
Sludge: 5,800 yd3 (10 feet
deep)
Soil: 3,600 yd3 (5 feet
deep) sludge, solids
Transformer Service Facility/ Soil: 3,500 tons
TSCA Demonstration
Arnold AFB, Site 10
Crab Orchard
Wildlife Refuge
Soil with debris: 10,000 tons
Soil: 40,000 tons
Anderson Development Soil: 4,000 tons
Biocides (pesticides), dioxins,
metals (mercury)
Volatile organic compounds
(methylene chloride, TCA,
styrene, toluene), metals (lead)
Biocides (pesticides), metals
(arsenic, mercury)
Site preparation
Treatability testing
Remedial design
Semivolatile organic compounds Remedial design
(hexachlorobenzene, penta-
chlorophenol), biocides (pesti-
cides), dioxins
PCBs Site preparation
Mixed organics, heavy metals Site preparation
PCBs and lead Predesign
4,4'-methylene bis Predesign
(2-chloroaniline) (MBOCA)
moisture content requires that additional energy be used to dry
out the soil before the melting process can begin, thus increas-
ing the cost. Other factors that influence the cost of remedia-
tion by ISV are: the amount of site preparation required;
the specific properties of the contaminated soil (e.g., dry
density); the required depth of processing; and the unit price
of electricity.
EPA Contact
Technology-specific questions regarding ISV may be
directed to:
Ms. Ten Richardson
U.S. Environmental Protection Agency
Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Cincinnati, Ohio 45268
(513)569-7949
Acknowledgments
This bulletin was prepared for the U.S. Environmental
Protection Agency, Office of Research and Development (ORD),
Risk Reduction Engineering Laboratory (RREL), Cincinnati, Ohio,
by Science Applications International Corporation (SAIC) un-
der Contract No. 68-CO-0048. Mr. Eugene Harris served as the
EPA Technical Project Monitor. Mr. Jim Rawe was SAIC's Work
Assignment Manager. Dr. Trevor |ackson (SAIC) was the
primary author. The author is especially grateful to Ms. Teri
Richardson of EPA-RREL, who contributed significantly by serv-
ing as a technical consultant during the development of this
document
The following other Agency and contractor personnel
have contributed their time and comments by participating in
the expert review meetings or peer reviews of the document:
Mr. Edward Bates
Mr. Briant Charboneau
Mr. Kenton Oma
Mr. Eric Saylor
EPA-RREL
Wastren, Inc.
Eckenfelder, Inc.
SAIC
Engineering Bulletin: In Situ Vitrification Treatment
•ttV.S. COVERNMCNT PRINTING OFFICE; I
• J5M47/MMO
-------
REFERENCES
1. Geosafe Corporation. In Situ Vitrification for Permanent
Treatment of Hazardous Wastes. Presented at Advances
in Separations: A Focus on Electrotechnologies for Prod-
ucts and Waste, Battelle, Columbus, 1989.
2. Innovative Treatment Technologies, Semi-Annual Status
Report (Fourth Edition). EPA/542/R-92/011, U.S. Envi-
ronmental Protection Agency, October 1992.
3. Conversations with Hansen, |. of Ceosafe. April 19,
1993.
4. Vitrification Technologies for Treatment of Hazardous
and Radioactive Waste. EPA/625/R-92/002, U.S. Envi-
ronmental Protection Agency, May 1992.
S. Ceosafe Corporation. Application and Evaluation Con-
siderations for In Situ Vitrification Technology: A Treat-
ment Process for Destruction and/or Permanent
Immobilization of Hazardous Materials. April 1989.
6. Technology Screening Guide for Treatment of CERCLA
Soils and Sludges. EPA/540/2-88/004, U.S. Environmen-
tal Protection Agency, 1988. pp. 55-60.
7. FitzPatrick, V.F., and |.E. Hansen. In Situ Vitrification for
Remediation of Hazardous Wastes. Presented at 2nd
Annual HazMat Central Conference, Chicago, Illinois,
1989.
8. Farnsworth, R.K., K.H. Oma, and C.E. Bigelow. Initial
Tests on In Situ Vitrification Using Electrode Feeding
Techniques. Prepared for the U.S. Department of Ener-
gy, under Contract DE-AC06-76RLO 1830, 1990.
9. In Situ Vitrification Technology Update. Ceosafe Corpo-
ration. November 1992.
10. Hansen, J.L, C.L Timmerman, and S.C. Liikala. Status
of In Situ Vitrification Technology: A Treatment Process
for Destruction and/or Permanent Immobilization. In:
Proceedings of Annual HazMat Management Confer-
ence International, Atlantic City, New Jersey, 1990. pp.
317-330.
11. Greene, |.C, et al. Comparison of Toxicity Results Ob-
tained from Eluates Prepared from Non-Stabilized and
Stabilized Waste Site Soils. In: Proceedings of the 5th
National Conference on Hazardous Wastes and Hazard-
ous Materials, Las Vegas, Nevada, 1988. pp. 77-80.
12. FitzPatrick, V.F., C.L. Timmerman, and |.L. Buelt. In Situ
Vitrification - An Innovative Thermal Treatment Technol-
ogy. Proceedings: Second International Conference on
New Frontiers for Hazardous Waste Management. EPA/
600/9-87/018F, U.S. Environmental Protection Agency,
1987. pp. 305-322.
13. Timmerman, C.L. In Situ Vitrification Of PCB Contami-
nated Soils. EPRI CS-4839. Electric Power Research Insti-
tute, Palo Alto,,California, 1986.
14. Timmerman, C.L. Feasibility Testing of In Situ Vitrifica-
tion of PCB-Contaminated Soil from a Spokane, WA
Site. Prepared for Geosafe Corporation, Kirkland, Wash-
ington, under Contract 14506, 1989.
15. Koegler, S.S. Disposal of Hazardous Wastes by In Situ
Vitrification. Prepared for the U.S. Department of En-
ergy, under Contract DE-AC06-76RLO 1830, 1987.
16. Farnsworth, R.K., et al. Engineering-Scale Test No. 4: In
Situ Vitrification of Toxic Metals and Volatile Organics
Buried in INEL Soils. Prepared for the U.S. Department
of Energy, under Contract DE-AC06-76RLO 1830, 1991.
17. Mitchell, S.j. In Situ Vitrification of Dioxin Contaminat-
ed Soils. Prepared for American Fuel and Power Corpo-
ration, Panama City, Florida, under Contract
2311211874, 1987.
18. Buelt, J.L., and S.T. Freim. Demonstration of In Situ Vit-
rification for Volume Reduction of Zirconia/Lime Slud-
ges. Prepared for Teledyne Wah Chang, Albany,
Oregon, under Contract 2311205327, 1986.
19. Timmerman, C.L Feasibility Testing of In Situ Vitrifica-
tion of Arnold Engineering Development Center Con-
taminated Soils. Prepared for the U.S. Department of
Energy, under Subcontract DE-AC05-84OR21400, 1989.
20. Correspondence from Geosafe Corp. to Mr. Edward R.
Bates (RREL), September 17, 1991.
United States
Environmental Protection Agency
Center lor Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK FIATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/540/S-94/504
-------
Section 15
-------
ALTERNATIVE TREATMENTS
STUDENT PERFORMANCE OBJECTIVES
At the conclusion of this unit, students will be able to:
1. Describe four emerging technologies that can be used to treat
contaminated water
2. Describe four emerging technologies used in treatment of
contaminated soils
3. Describe four treatments for solid waste that are considered
to be in the emerging stage.
NOTE: Unless otherwise stated, the conditions for
performance are using all references and materials
provided in the course, and the standards of
performance are without error.
7/95
-------
TREATMENTS
ALTERNATIVE TREATMENT
• Contaminated water treatment
• Soil treatment
• Solid waste treatment
3-1
S-2
CONTAMINATED WATER
TREATMENT
Perox-Pure ultraviolet (UV) oxidation
system
Ultrox® UV oxidation system
Metal-enhanced reductive dehalogenation
High-energy electron irradiation
S-3
NOTES
7/95
Alternative Treatments
-------
NOTES
UV RADIATION/OXIDATION
• Initial attack of the target organics by UV
light
• Transformation of O3 and/or H2O2 to highly
reactive (OH) radicals
• Applicable to chlorinated or nonchlorinated
organics
3-4
PEROX-PURE UV OXIDATION SYSTEM
• Destroys organic contaminants in water
• Uses UV radiation and hydrogen peroxide
• Produces hydroxyl radicals
• Applied successfully at 80 sites
s-s
PEROX-PURE UV OXIDATION SYSTEM
H2o2 — S^y-|
^^^^^^i
S> ° o o :
UV Lamps^ ° ° q °
Influent ° ° _ ° °°
Xx oo o 0°
U.S. EPA 1904d
) 0 0 o =31
o C o o X
> °° o _ ?o Effluent
D >iJ O /-i ^
0 ° O
D ° o 0°! 3o
> o 0 o 0|o
o oo o °
s-e
Alternative Treatments
7/95
-------
NOTES
ULTROX® UV OXIDATION SYSTEM
• UV radiation, hydrogen peroxide, and
ozone
• Similar to Perox-Pure plus ozone
• Fully commercial - 30 systems installed
• Flow rates from 5 to 1050 gpm
8-7
ULTROX® UV OXIDATION SYSTEM
HA
03
=S)~I
/
UV Lamps
Influent
X^ "V
US. EPA 1094d
x"
c
^-.
o
0
0
O
o
o
o
0
O
D,
C
*
O
0
0
0
o
o
o
)
0
0
o
O
0
O
0
o
0
O
o
0
D
0
3
O
3
O
O
0
o
O
O
o<
o
o
0
0
0
3
O
o
)
O
o
O
0
O
C
0
O
o
0
0°
o
O
O
o
)
0
0
o
0
£
0°
o
o
Do
o
o
Effluent
3-6
ULTROX® TREATMENT COSTS
COMPONENTS
Ozone @ 0.06/Kwh
H2O? @ 0.75/lb
UV including power and annual lamp replacement
O & M cost
Capital amortization
Total treatment costs
Flow rate: 210 gpm
Influent cone.: 5500 pg/l TCE
Effluent cone.: 1 A/g/l TCE
U.S. EPA 1S04d
COST
0.119
0.118
0.133
0.440
0.290
$0.75/1 000 gal
S-9
7/95
Alternative Treatments
-------
NOTES
w
METAL ENHANCED
DEHALOGENATION
• In-situ groundwater treatment
• Permeable reactive metal (iron) wall
• Degradation of halogenated organics
• Two site demonstrations
• Future ex-situ reactor processes
8-10
IN-SITU PERMEABLE
TREATMENT WALL
Groundwater with
chlorinated
organic
Permeable —:
treatment wall filled
with reactive metal
Treated groundwater
S-11
FUNNEL AND GATE SYSTEM
Impermeable barrier
(sheet piling)
Treated
groundwater
Permeable treatment
sections with
reactive metal
S-12
Alternative Treatments
7/95
-------
NOTES
EX-SITU METAL-ENHANCED
ABIOTIC SYSTEM
Air Filter Access port , . <-- Vent
eliminator \Ftowmeter ^ p1
ill I -Tfc—1• Sealing flange
for top
I
Influent
Filter sand
us. EPA fees*
Reactive metal
medium
Collector line
=F~
Effluent
S-13
HIGH ENERGY ELECTRON
IRRADIATION
• Destroys chlorinated hydrocarbons
dissolved in water
• Directs electrons into thin stream of water
• Produces aqueous electrons, hydrogen
radicals, and hydroxyl radicals
U.S. EPA 1994d
S-14
HIGH ENERGY ELECTRON
IRRADIATION (cont.)
• Converts organics to carbon dioxide,
water, and salts
• Applicable to at least 50 organic
compounds
• Treats > 170,000 gallons per day
commercial facility
U.S. EPA 1994d
S-1S
7/95
Alternative Treatments
-------
NOTES
THE MOBILE ELECTRON BEAM
HAZARDOUS WASTE TREATMENT SYSTEM
Control Room
Pumping System Electron Accelerator Office/Lab
Alf duel
J
\
Alf duct
.this?
ling
U.S. EPA ISMtf
8-16
SOIL TREATMENT
BESCORP and COGNIS
Base catalyzed decomposition (BCD)
Radio frequency heating [v
Cyanide bioremediation process (Pintail
Systems Inc.)
8-17
BESCORP and COGNIS
• Soil washing combined with chemical
treatment
• BESCORP - volume reduction and metal
recovery
• COGNIS - acid extraction process
u.s. EPA
S-18
Alternative Treatments
7/95
-------
NOTES
BESCORP and COGNIS (cont.)
• Heavy metals recovery
• 12-15 tons per hour (soils)
• Twin Cities Army Ammunition Plant
us. EPA
S-18
TERRAMET® LEAD REMOVAL PROCESS
To chemical
leaching proceii
U.S. EPA 1S»4d
S-20
TERRAMET® LEAD REMOVAL PROCESS
Chemical Leaching Stage
Soil finet from
Separation Stage
Oewatered 1/4* over«lze from
Physical Separation Stage
Sand from
Separation Stage
T
Lime
Clean, dewatered,
neutralized toll
Lead concentrate
to recyder
U.S. EPA ia04d
S-21
7/95
Alternative Treatments
-------
NOTES
BCD PROCESS
Chemical dehalogenation technology for
soils
Thermal desorption unit removes
chlorinated organics
Condensed organics dechlorinated by
mixing with reagents
PCR dioxins, and furans removed in site
demonstration
8-32
BCD PROCESS (cont.)
Contaminated materials
or screened soils
Feed hopper
Oechlori nation
reagents
_^ To vapor
recovery system
S~\
BCD solids reactor medium
temperature thermal
desorption (MTTD)
To cooling
screw conveyor
us. EPA
8-23
BCD PROCESS (cont.)
| Vapor recovery system
| Oil Water Condensing
scrubbers scrubbers unit
thermal ^
desorption I
unit '
1
1
L
E= /_
1
To atmosphere
^o-I !
1 — 1
1— 1 1
Carbon
polisher I
1
To aqueous To oily
condensate storage condensate storage
U.S. EPA 1904d 8-24
Alternative Treatments
7/95
-------
BCD
From BCD
solids reactor!
| Water spray
Cooling j *„« _* 1
Cooling screw
conveyor
PROCESS (cont.)
Treated 1
water '
From vapor recovery system
Aqueous Oily
oondensate oondensate
storage storage
-i' 1 J=f
1 MX*"; BC
1 l/\ * llai
Ro%«r «^£n Cond'n"f TTC
^
OnsNe backtil f^Oeconlamlnated^
or j solids
ottsKa dleposal I container |
u
U.S. EPA 1904d
U
Oeohlorlnation
-, I reagents
o 1
Id
1or
H)
•^ Treated
Oil/HC
Recycled orfslte
S-25
RADIO FREQUENCY HEATING
Uses electromagnetic energy to heat soils
Enhances soil vapor extraction
Produces soil temperatures of up to 300°C
S-28
RADIO FREQUENCY IN-SITU
HEATING SYSTEM
Adjusted in the field
to match
Contaminated aluminum
RF shield
RF amplifier
and Stage 2
matcher
Vapor barrier and RF
shield on surface
US. EPA tee*/
Shielding electrode
rows
S-27
NOTES
7/95
Alternative Treatments
-------
NOTES
KAI ANTENNA SYSTEM
RF'touro*
Control
US. EPA 199*1
8-26
CYANIDE BIOREMEDIATION
• Microbial detoxification of cyanide
• Elevated concentration of natural soil
bacteria
• Applied in drip or spray irrigation
• Bacteria grown in spent ore infusion broth
3-28 ,
SPENT ORE BIOREMEDIATION
PROCESS
Cyanide-leached ore residue
Sump
Application bacteria
Leachate solution collection
US. EPA 19044
S-30
Alternative Treatments
10
7/95
-------
NOTES
SOLID WASTE TREATMENT
• Cyclone furnace
• Flame reactor f
• Plasma arc P^
CYCLONE FURNACE
CYCLONE FURNACE (cont.)
• Inert exits as vitrified slag
• Slag easily passes TCLP
• One site demonstration
• $465 to $529 per ton
3-31
Designed to melt high-ash fuels
Can process:
- Wastes with high heavy metals
- Organics in soil and sludge
- Low volatility radionuclides
S-32
S-33
7/95
11
Alternative Treatments
-------
NOTES
V
CYCLONE FURNACE
Combustion air
Inside furnace
Slag tap
Natural gas
Injectors
Natural gas
Soil injector
- Slag
quenching tank
U.S. EPA 1004d
S-34
FLAME REACTOR
• Metal-contaminated waste treatment
• Flash-smelting, hydrocarbon-fueled system
• Products
- Nonleachable, glasslike slag
- Heavy-metal-enriched oxide, recyclable
- Metal alloy (in some cases)
30,000 ton/yr existing commercial plant
8-3S
HRD FLAME REACTOR PROCESS FLOW
Efllutnt ilag
Oxkte product
U.S. EPA 1904d
S-36
Alternative Treatments
12
7/95
-------
PLASMA ARC
• Heavy-metal, organic, and mixed waste
• Plasma arc furnace creates molten bath
• Waste heated to 3200°F in centrifuge
• Off-gas treated
• Nonleachable slag discharged to mold
• Two tons waste processed in
demonstration
3-37
I//
PLASMA ARC CENTRIFUGAL TREATMENT
(PACT) FURNACE
U.S. EPA I994d
S-38
NOTES
7/95
13
Alternative Treatments
-------
REFERENCES
Chen, Chien T. No date. Iron Enhanced Abiotic Degradation of Chlorinated Hydrocarbons. U.S.
Environmental Protection Agency, Releases Control Branch, Edison, NJ.
Gilham, Robert W., and Stephanie F. O'Hannesin. 1994. Enhanced Degradation of Halogenated
Aliphatics. Waterloo Centre for Groundwater Research, University of Waterloo, Waterloo, Ontario.
Gilham, Robert W., and Stephanie F. O'Hannesin. 1994. Enhanced Degradation of Halogenated
Aliphatics by Zero-Valent Iron. Groundwater 32(6):958-967.
Gilham, Robert W., Stephanie F. O'Hannesin, and W. Scott Orth. 1993. Metal Enhanced
Degradation of Halogenated Aliphatics: Laboratory Tests and Field Trials. Paper Presented at the
1993 HazMat Conference, Chicago, Illinois, March 9-11,1993. Waterloo Centre for Groundwater
Research, University of Waterloo, Waterloo, Ontario.
Starr, Robert C., and John A. Cherry. 1994. In Situ Remediation of Contaminated Ground Water:
The Funnel-and-Gate System. Groundwater 32(3):465-476.
U.S. EPA. 1991. Engineering Bulletin: Chemical Oxidation Treatment. EPA/540/2-91/025. U.S.
Environmental Protection Agency, Center for Environmental Research Information, Cincinnati, OH.
U.S. EPA. 1992a. Engineering Bulletin: Pyrolysis Treatment. EPA/540/S-92/010. U.S.
Environmental Protection Agency, Center for Environmental Research Information, Cincinnati, OH.
U.S. EPA. 1992b. Engineering Bulletin: Supercritical Water Oxidation. EPA/540/S-92/006. U.S.
Environmental Protection Agency, Center for Environmental Research Information, Cincinnati, OH.
U.S. EPA. 1992c. Superfund Innovative Technology Evaluation: Babcock and Wilcox Cyclone
Furnace Vitrification Technology, Applications Analysis Report. EPA/540/AR-92/017. U.S.
Environmental Protection Agency, Center for Environmental Research Information, Cincinnati, OH.
U.S. EPA. 1992d. Superfund Innovative Technology Evaluation: Demonstration Bulletin, Cyclone
Furnace Soil Vitrification Technology. EPA/540/MR-92/011. U.S. Environmental Protection
Agency, Center for Environmental Research Information, Cincinnati, OH.
U.S. EPA. 1992e. Superfund Innovative Technology Evaluation: Emerging Technology Bulletin,
Electron Beam Treatment for Removal of Trichloroethylene and Tetrachloroethylene from Streams
and Sludge. EPA/540/F-92/009. U.S. Environmental Protection Agency, Center for Environmental
Research Information, Cincinnati, OH.
U.S. EPA. 1992f. Superfund Innovative Technology Evaluation: Emerging Technology Bulletin,
Laser Induced Photochemical Oxidative Destruction. EPA/540/F-92/004. U.S. Environmental
Protection Agency, Center for Environmental Research Information, Cincinnati, OH.
Alternative Treatments 14 7/95
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U.S. EPA. 1992g. Superfund Innovative Technology Evaluation: Emerging Technology Bulletin,
The Babcock and Wilcox Cyclone Furnace Soil Vitrification Technology. EPA/540/F-92/010. U.S.
Environmental Protection Agency, Center for Environmental Research Information, Cincinnati, OH.
• j ; - "' i
U.S. EPA. 1992h. Superfund Innovative Technology Evaluation: Emerging Tedmology^uriimary,
Babcock and Wilcox Cyclone Furnace Vitrification. EPA/540/SR-93/507. U.S. Environmental
Protection Agency, Center for Environmental Research Information, Cincinnati, OH.
' *i'.
U.S. EPA. 19921. Superfund Innovative Technology Evaluation: SITE Program Demonstration
Test, Technology Demonstration Summary, Technology Evaluation Report: Retech, Inc. Plasma
Centrifugal Furnace, Butte, MT. EPA/540/S5-91/007. U.S. Environmental Protection Agency,
Center for Environmental Research Information, Cincinnati, OH.
U.S. EPA. 1992j. Superfund Innovative Technology Evaluation: Technology Demonstration
Summary, Babcock and Wilcox Cyclone Furnace Vitrification. EPA/540/SR-92/017. U.S.
Environmental Protection Agency, Center for Environmental Research Information, Cincinnati, OH.
U.S. EPA. 1992k. Superfund Innovative Technology Evaluation: Technology Demonstration
Summary, Horsehead Resource Development Company, Inc., Flame Reactor Technology.
EPA/540/S5-91/005. U.S. Environmental Protection Agency, Center for Environmental Research
Information, Cincinnati, OH.
U.S. EPA. 1993a. Superfund Innovative Technology Evaluation: Demonstration Bulletin, CAV-
OX Ultraviolet Oxidation Process Magnum Water Technology. EPA/540/MR-93/520. U.S.
Environmental Protection Agency, Center for Environmental Research Information, Cincinnati, OH.
U.S. EPA. 1993b. Superfund Innovative Technology Evaluation: Demonstration Bulletin, Perox-
pure Chemical Oxidation Treatment. EPA/540/MR-93/501. U.S. Environmental Protection Agency,
Center for Environmental Research Information, Cincinnati, OH.
U.S. EPA. 1993c. Superfund Innovative Technology Evaluation: Emerging Technology Bulletin,
Destruction of Organic Contaminants in Air Using Advanced Ultraviolet Flashlamps. EPA/540/F-
93/501. U.S. Environmental Protection Agency, Center for Environmental Research Information,
Cincinnati, OH.
. •.." £ . . * .
U.S. EPA. 1993d. Superfund Innovative Technology Evaluation: Emerging technology Bulletin)"
Electron Beam Treatment for the Removal of Benzene and Toluene from Aqueous Streams and
Sludge. EPA/540/F-93/502. U.S. Environmental Protection Agency, Center for Environmental.
Research Information, Cincinnati, OH. _
U.S. EPA. 1993e. Superfund Innovative Technology Evaluation: Emerging Technology Summary,
Destruction of Organic Contaminants in Air Using Advanced Ultraviolet Flashlamps. EPA/540/SR-
93/516. U.S. Environmental Protection Agency, Center for Environmental Research Information,
Cincinnati, OH.
U.S. EPA. 1993f. Superfund Innovative Technology Evaluation: Emerging Technology Summary,
Laser Induced Photochemical Oxidative Destruction of Toxic Organics in Leachates and
7/95 15 Alternative Treatments
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Groundwater. EPA/540/SR-92/080. U.S. Environmental Protection Agency, Center for
Environmental Research Information, Cincinnati, OH.
U.S. EPA. 1993g. Superrand Innovative Technology Evaluation: Emerging Technology Bulletin,
Removal of Phenol from Aqueous Solutions Using High Energy Electron Beam Irradiation.
EPA/540/F-93/509. U.S. Environmental Protection Agency, Center for Environmental Research
Information, Cincinnati, OH.
U.S. EPA. 1993h. Superfund Innovative Technology Evaluation: Technology Demonstration
Summary, Peroxidation Systems, Inc. Perox-pure Chemical Oxidation Technology. EPA/540/SR-
93/501. U.S. Environmental Protection Agency, Center for Environmental Research Information,
Cincinnati, OH.
U.S. EPA. 1994a. Superfund Innovative Technology Evaluation: Demonstration Bulletin, Radio
Frequency Heating, HT Research Institute. EPA/540/MR-94/527. U.S. Environmental Protection
Agency, Center for Environmental Research Information, Cincinnati, OH.
U.S. EPA. 1994b. Superfund Innovative Technology Evaluation: Demonstration Bulletin, Radio
Frequency Heating, KAI Technologies, Inc. EPA/540/MR-94/528. U.S. Environmental Protection
Agency, Center for Environmental Research Information, Cincinnati, OH.
U.S. EPA. 1994c. Superfund Innovative Technology Evaluation: Technology Demonstration
Summary, CWM PO*WW*ER Evaporation-Catalytic Oxidation Technology. EPA/540/SR-93/506.
U.S. Environmental Protection Agency, Center for Environmental Research Information, Cincinnati,
OH.
U.S. EPA. 1994d. Superfund Innovative Technology Evaluation Program: Technology Profiles,
Seventh Edition. EPA/540/R-94/526. U.S. Environmental Protection Agency, Office of Research
and Development, Risk Reduction Engineering Laboratory, Cincinnati, OH.
U.S. EPA. 1995a. SITE Program Fact Sheet: Demonstration of the EnviroMetal Technologies,
Inc. Metal-Enhanced Abiotic Degradation Technology. U.S. Environmental Protection Agency,
Office of Solid Waste and Emergency Response, Office of Research and Development, Washington,
DC. ......
U.S. EPA. 1995b. Superfund Innovative Technology Evaluation: Site Technology Capsule, ITRI
Radio Frequency Heating Technology. EPA/540/R-94/527a. U.S. Environmental Protection
Agency, Center for Environmental Research Information, Cincinnati, OH.
Alternative Treatments 16 7/95
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