United States
         Environmental Protection
         Agency
Center for Environmental
Research Information
Cincinnati OH 45268
EPA/625/4-89/020
September 1989
         Technology Transfer
&EPA   Seminar Publication

         Corrective Action:
         Technologies and
         Applications

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                                  EPA/625/4-89/020
                                  September 1989
       Seminar Publication
        Corrective Action:
Technologies and Applications
       U.S. Environmental Protection Agency
            Cincinnati, OH 45268
                              Printed on Recycled Paper

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                                 Disclaimer
This document  has  been reviewed in  accordance with  U.S.  Environmental  Protection
Agency  policy and approved for publication. Mention of trade  names  or commercial
products does not constitute endorsement or recommendation for use.

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                                    Preface
This seminar publication is wholly based on edited versions of presentations made at U.S.
Environmental  Protection  Agency  (EPA)  Technology  Transfer Seminars  entitled
"Corrective Actions:   Technologies  and Applications".   These  seminars were  held in
Houston, Texas (March 30-31,1988); Atlanta, Georgia (April 19-20,  1988); Chicago.lllinois
(May  25-26,  1988);  Philadelphia, Pennsylvania (June 7-8, 1988); and Los  Angeles,
California (June 14-15, 1988).


The following lists the authors whose presentations are summarized  in this publication and
who participated in the seminar series.

 - Ken Whitaker - Engineering Science
 - Brent Huntsman - Terran Corporation
 - Charles Parmele -  IT Corporation
 - Evan Nyer and George Skladany - DETOX, Inc.
 - Fred Hall - PEI
 - Ed Martin - PEER Consultants, P.C.
 - James Nash - Roy F. Weston
 - Barbara Cormier -  PEER Consultants, P.C.

H. Douglas Williams (EPA Center for Environmental Research Information, Cincinnati, OH)
provided  guidance and review for this document. Editorial  and  review assistance was
provided by Dr. J.T. Swartzbaugh and Mr. Robert Mentzer of PEER Consultants, P.C.

This report has been  reviewed by the U.S. Environmental Protection  Agency and approved
for publication.  The process  alternatives,  trade names, and  commercial products are
presented as examples and are  not  endorsed or recommended  by  the EPA.   Other
alternatives may exist and may be developed. In addition, the information in this document
does not necessarily  reflect the policy of the EPA, and no official  endorsement should be
inferred.
                                        Ml

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                                    Abstract
The Corrective Action Program is currently under development by the RCRA Enforcement
Division  in the  Office of  Waste  Programs  Enforcement.   To  provide  engineers and
scientists involved in RCRA Corrective Action activities, from a industrial perspective, with
insight into the  selection and evaluation of  technologies suitable  for application in  the
containment and treatment  of hazardous releases.

Rve seminars were held in the  spring and summer of 1988  in Houston.Texas; Chicago,
Illinois; Atlanta, Georgia; Philadelphia, Pennsylvania; and Los Angeles, California.  Support
for  the  seminars  came  from the RCRA Enforcement  Division of the Office of Waste
Program Enforcement. This publication contains edited versions of what was presented at
each of the five seminars.

The seminar publication provides information on the identification, selection and application
of technologies suitable for controlling and treating releases of hazardous wastes or their
constituents from RCRA treatment,  storage and disposal  facilities.   Applications  of
technologies are  presented, where appropriate, to  demonstrate the  suitability of treatment
options  for specific  waste types.  In addition, factors to consider  when implementing
corrective measures at operating facilities are reviewed.  Whenever possible,  information
has been updated and revised to take into account recent changes in the regulations.

This publication  is not a  design  manual,  nor does it include all the  technologies available
for corrective action.  Additional  sources should be consulted for more detailed information
and design criteria.   State and local authorities  should  be contacted for regulations as
needed in local areas.
                                         IV

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                                        Contents
 Preface	   mj
 Abstract  	.-	'.'.'.'.'.'.'.'.'.'.'..  iv
 Tables	  vi
 Figures  	'.'.'..'.'.'.'.'  vii
 List of Acronyms  	  jx

 Chapter 1  Engineering Overview of the Corrective Action Program	  1

    What Triggers Corrective Action   	  1
    The Corrective Action Plan	'.'.'.'.  2
    Interim Measures	  2
    References  	'.'.'.'.  4

 Chapter 2  Engineering Considerations in the Facility Investigation   	  5

    Pre-lnvestigation Evaluation of Corrective Measures
       Technologies  	  5
    Field Diagnostic Tools	'.'.'.'.'.'.'.I'.'.'.'.  6
    Laboratory and Bench-Scale Studies  	'.'.'.'.'.'.'.'.'.'.'.'.' 17
    References	   17

 Chapter 3  Containment Options  	   -j g

    Groundwater Containment	   1 g
    Containment and Control Options for Gaseous Wastes from Soils	   22
    Methods to Control Releases from Surface Impoundments  	   24
    References	    25

 Chapter 4  Engineering  Considerations for the Corrective Measures Study  	   27

    Identification and Development of Corrective Measures Alternative(s)    	   27
    Evaluation of the Corrective Measure Alternative(s)	   28
    References	   ^

 Chapter 5 Technology Options for the Treatment of Wastes and Waste Streams  	   31
    Chemical Treatment Processes for Corrective Action  	   31
    Biological Processes for Corrective Action	   37
    Thermal Processes for Corrective Action	'.'.'.'.'.'.'.'.'.'.'.'.'.'.'.   47
    References	   57

Chapter 6 Pretreatment and Post Treatment Options   	   5g
    Separation Techniques (Pretreatment Options)	   5g
    Solidification/Stabilization Processes (Post Treatment Options)	'.'.'.'.'.'.'.'.'.   64
    References	   73


Chapter 7 Engineering Considerations for Corrective Measures Implementation 	   75
    Corrective Measures Design  	   75
    References	   77

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                                       Tables
No.

1     Examples of Interim Measures 	
2     Containment/Recovery Options and Data Needs by Media
3     Summary of Important Geologic Information	
4     Summary of Basic Technologies and Data Needs to Modify
         the Degree of Hazard of Wastes   	
5     Important Physical Treatment Data Needs   	
6     Geophysical Techniques, Their Application and Limitations
       at Hazardous Waste Sites .	
7     Comparison of Precipitation Reagents   	•
8     Biodegradable RCRA-Regulated Organic Compounds .   . .
9     Nutrients for Biological Treatment	
10    Incineration Type for Various Waste Matrices  	
11    Debris Identification	:	
12    Applicability of Solidification/Stabilization for
         Specific Contaminants   .; .	
                                                                                   Page
 3
 7
 8

 g
11

12
33
40
40
51
60

67
                                           VI

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                                 Figures
No.
                                                                        Page
1
2a
2b
3a
3b
4
5

6
7a
7b
8
9a
9b
9c
10a
10b
11
12
13
14
15
16
17
18
19
20
21
22
23

24
25
26

27
28
29
30
31
32
33
34
35
36
37
38
Alteration of function and data needs 	
Boundaries of a contaminant plume 	
Subsurface stratigraphic relationship 	
Cross-section of seismic refraction measuring technique 	
Log of seismic refraction results 	
Soil vapor probe and sampling train 	
Comparison of TCE and TCA concentration distribution by
groundwater and soil gas samples, southwestern U.S. study 	
Containment options 	
Containment using extraction wells 	
Plume diversion using injection wells 	
The use of subsurface drainage to contain a leachate plume 	
Plan of downgradient placement 	
Plan of upgradient placement with drain 	
Plan of circumferential wall placement 	 	
Passive gas control using a permeable trench 	
Passive gas control synthetic membrane 	
Gas collection/recovery system 	
Chemical processes 	 	
Flow diagram of a generic chemical treatment process 	
pH adjustment system 	
Solubilities of metal hydroxides as a function of pH 	
General process flowsheet for chemical oxidation 	
Hydrolysis of refractory organics 	
Photolysis flow diagram 	
Site of formaldehyde release 	
Diagram of in-situ treatment 	
Biological processes 	
Diagram of the suspended growth system 	
Life-cycle design - installed system at southern Texas
site (treating phenol in a brine aquifer) 	
Diagram of the film flow reactor 	
DETOX H-series submerged fixed-film biological reactor 	
Process diagram for revised groundwater and solvent
wastes biological treatment system 	
Houston Chemical Co. response actions 	
Conceptual strategy for determining burnability 	
Pretreatment option logical decision flow chart 	
Liquid injection incineration system 	
Schematic of plasma arc system 	
Rotary kiln incineration system 	
Fluidized bed reactor 	
Circulating fluidized bed boiler 	
Process flow diagram of infrared incineration system 	
Separation techniques for various particle sizes 	
Cyclone 	
Jigging 	
	 7
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                                   VII

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                                Figures (Continued)
39
40
41
42
43
44
45
Magnetic separator	   63
API oil/water separator	   64
Shell corrugated-plate interceptor	   65
Mobile soils washing system	   66
Separator nozzle  	• • •  •	   ^7
Cernent-based stabilization process	   69
Lime-based (pozzolanic) stabilization process  	   71
                                           VIII

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              List of Acronymns

 ARC           Air Pollution Control
 ARC           Dir Pollution Control Device
 BOD           Biochemical OxygenDemand
 CAP           Corrective Action Plan
 CFR           Code of Federal Regulations
 CM            Corrective Measures
 CMI           Corrective Measures Implementation
 CMS           Corrective Measures Study
 COD           Chemical Oxygen Demand
 DRE           Destruction Removal Efficiency
 EM            Electromagnetic Conductivity
 EP Tox         Extraction Procedure Toxicity Test
 EPA           Environmental Protection Agency
 FML           Flexible Membrane  Liner
 GC            Gas Chromatograph
 GC/MS         Gas Chromatograph/Mass Spectrophotometer
 gpm           gallons per minute
 GPR           Ground Penetrating Radar
 HHE           Human Health and the Environment
 HWF           Hazardous Waste Fuel
 kw            kilowatt
 Ib/hr           pound per hour
 MAG           Magnetometry
 MD            Metal Detection
 MEK           Methyl Ethyl Ketone
 mg/€           milligrams per liter
 MMBtu/hr       million Btu per hour
ORP           Oxidation Reduction Potential
PAC           Powdered Activated Carbon
PCB           Polychlorinated Biphenyl

                       ix

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        List of Acronyms (Continued)

PGP           Pentachlorophenol
PID            Photoionization Detector
ppb            parts per billion
ppm           parts per million
PVC           Polyvinyl Chloride
RBC           Rotating Biological Contactor
RCRA          Resource Conservation and Recovery Act
RFA           RCRA Facility Assessment
RFI            RCRA Facility Investigation
SBR           Sequencing Batch Reactor
SITE Program   Superfund Innovative Technology Evaluation
               Program
TCDD          Trichlorodibenzodioxin
TCLP          Toxicity Characteristic Leaching Procedure
TOC           Total Organic Carbon
tph            tons per hour
USATHAMA    U.S. Army Toxic and Hazardous Materials;
                   Agency
UV            Ultraviolet
VOC           Volatile Organic Compounds
p.g/f           micrograms per liter

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                                          Chapter 1
             Engineering Overview of the Corrective Action Program
The technical differences between site problems at
RCRA facilities and CERCLA sites sometimes may
be difficult to distinguish, owing to similarities in
present or past uses of the site, in hydrogeologic
setting, and/or in the types of substances disposed,
spilled, or otherwise managed at  the site.
Consequently, many technical aspects of the study
and remediation of releases of hazardous wastes and
constituents from RCRA facilities often will closely
parallel those at Superfund sites, and cleanups under
both  statutes  must achieve similar  goals for
protection of public health and the environment.
Additionally, activities  which would be  termed
removal actions or expedited response actions under
CERCLA may be  undertaken by owners and
operators under RCRA. In the RCRA context, such
actions are  termed interim measures, as  will be
discussed in subsequent chapters.

Differences between the two programs may  arise in
several areas: (1) who performs the work, (2) extent of
the analyses and/or cleanup performed, (3) factors
considered in selecting a final remedy, and (4) use of
the site following cleanup. First, a Superfund cleanup
may be undertaken by EPA under CERCLA Section
104, or by the responsible parties under EPA or state
supervision under CERCLA Section 106. Corrective
actions at RCRA facilities, on the other  hand, are
developed and implemented by the owner/operator
under EPA or state supervision, either through the
facility permit or  an enforcement order. Second,  at
some RCRA facilities the Corrective Action process
may be somewhat more  streamlined than  at a
CERCLA site. This could occur in situations where
much is already known about the wastes and the site
at the initiation of Corrective Actions from  the Part B
permit application and other submittals; and, where
the release  problem is relatively  minor or the
remedial alternatives to address it are  relatively
minor or the remedial alternatives to address it are
relatively straightforward or self-evident. Third,
while the remedy selection factors in the draft RCRA
Corrective Action regulations (40 CFR 264 Subpart
S) are expected generally to parallel those offered in
the proposed revisions  to Superfund's  National
Contingency Plan, cost and cost-effectiveness may
not be used as a basis for selecting remedies under
the RCRA statute. Finally, in many cases Corrective
Actions at a RCRA facility may culminate in its
return to normal operating status;  while at most
Superfund  sites (and at some RCRA  facilities
undergoing Corrective Action), these  activities
typically culminate in final cleanup or closure of the
site. These and other factors might lead to selection
and implementation of different corrective measures
at otherwise similar RCRA and Superfund sites.

As  of this writing, the  proposed Subpart S
regulations describing many procedural  aspects of
the RCRA Corrective Action program have not been
published. However, two documents provide the
framework for directing the  development of the site-
specific work to be performed by the owner/operator
in the facility's  Corrective Action  program: the
RCRA Corrective Action Plan - Interim Final (U.S.
EPA, 1988a) and RCRA Corrective Action Interim
Measures - Interim Final (U.S. EPA, 1988b). These
can be used to develop site-specific schedules of
compliance for incorporation into a permit or an
enforcement order. From an engineering perspective,
these documents provide scopes of work that can
assist owner/operators and  engineers in planning
each phase of a facility-wide Corrective Action
program, and in the formulation and implementation
of interim  measures, respectively.  Additional
guidance currently is under development.
What Triggers Corrective Action

A common question is "What triggers Corrective
Action?" There is no single answer. In general, any
indicator  that a release of hazardous wastes  is
occurring  (or has occurred) can serve as a trigger.
Thus, a fish kill, a reported  spill,  contaminated
drinking water or contamination in monitoring wells
are some examples of conditions that may result  in
the EPA's initiating a Corrective Action program. An
initial step may be a RCRA Facility Assessment
(RFA), which is conducted by the EPA and intended
to identify releases or potential releases of hazardous
wastes and/or constituents. Usually the RFA  is
completed before the Corrective Action process  is
initiated. If releases or potential releases are found
that  may threaten  public health and  the
environment, the  Agency may require the owner

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and/or operator to develop a Corrective Action Plah to
address the releases.
The Corrective Action Plan
The Corrective Action Plan (CAP) relies on }the
sequential performance of activities which are
conventional engineering practices. These activities
include problem identification, development and
evaluation of alternatives, and the implementation of
the selected alternative. The three analogous phases
identified in the CAP are as follows:
•   RCRA  Facility Investigation (RFI)  -  site
    characterization  and  pre-investigation
    identification of possible containment/treatment
    technologies',                            ,
    Corrective Measures Study (CMS) - the conduct
    of detailed feasibility studies of  the cleanup
    alternatives identified;
•   Corrective Measures Implementation (CMI) -
    those activities associated with the design and
    construction of the technology options selected
    and with performance monitoring.
The CAP can serve as the technical framework for a
Corrective Action program. The CAP provides a
"menu" of activities or information requirements
that may be necessary for each phase of the process.
Site-specific conditions and the nature and extent of
the contamination will determine which tasks will be
necessary. The necessary tasks will be enforceable
through permit conditions or by an administrative
order or judicial action. The CAP can serve as a
flexible engineering guide for the  regulajtory
community in implementing their own Corrective
Action Program.
Interim Measures

At this writing, the Interim Final guidance for the
regulatory community with regard to interim
measures is available (U.S. EPA, 1988). Based on
this guidance,  the general concepts for the
application of interim measures can be identified.

Where there is an imminent threat to human health
and the  environment, as well  as in  some  non-
emergency situations, the regulatory agency may
ascertain that a response is appropriate prior to the
completion of the RCRA Facility Investigation or the
Corrective Measures Study. Hence, the decision for
interim  measures can  be  made based on the
immediacy as well as the magnitude of the potential
threat to human health  or the  environment; the
nature  of appropriate  Corrective Action; the
implications of deferring Corrective Action until the
RCRA Facility Investigation and Corrective Measure
Study is complete; and other factors.

Once a decision is made that interim measures are
needed,  then the next question is  what interim
measures might  be required for this particular
situation. Examples of interim measures for various
RCRA treatment, storage  and disposal facilities, and
for various release types are listed in Table 1. Note
that these are examples; their inclusion does not infer
either guidance or approval.

Interim measures may be separate from the
comprehensive Corrective Action plan but should be
consistent with, and integrated  with, any longer-
term Corrective  Action  (e.g., corrective measure
through an order, an operating permit, a post-closure
permit or interim status  closure requirements).  To
the extent possible, interim measures should not
seriously complicate  the  ultimate physical
management of hazardous wastes or constituents,
nor should they present or exacerbate  a health or
environmental threat. Interim measures may add
additional costs or work to the comprehensive
Corrective Action. Such added costs or work do not
preclude implementation of an interim measure.

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Table 1. Examples of Interim Measures
The following is a list of possible interim measures for various units and release types.  This list is not
considered to be all-inclusive. More information is available through the Interim Measures Guidance •
Interim Final (U.S. EPA,  1988b).
 Containers
   1.
   2.
   3.
   4.
   5.
   6.

 Tanks
   1.
   2.

 Surface Impoundments
   1.
   2.
   3.
   4.
   5.
   6.
  7.
 Landfills
  1.
  2.
  3.
  4,
  5.
  6.
  7.
Waste Piles
  1.
  2.
  3.
  4.
Soils
  1.
  2.
  3.

Ground water
  1.
  2.
  3.
  4.
  5.

Surface Water Releases
(Point and Non-point)
  1.
  2.
  3.
  4.
  5.
 Overpack/Redrum
 Construct Storage Area; Move to New Storage Area
 Segregation
 Sampling and Analysis
 Treatment, Storage and/or Disposal
 Temporary Cover
 Overflow; Secondary Containment
 Leak Detection/Repair; Partial or Complete Removal
 Reduce Head
 Remove Free Liquids and Highly Mobile Wastes
 Stabilize/Repair Side Walls, Dikes or Liner(s)
 Temporary Cover
 Run-off/Run-on Control (Diversion or Collection Devices)
 Sample and Analyze to Document the Concentration of Constituents
 Left in Place When a Surface Impoundment Handling Characteristic
 Wastes is Clean Closed
 Interim Groundwater  Measures (See Groundwater Section of this
 table)
 Run-off/Run-on Control (Diversion or Collection Devices)
 Reduce Head on Liner and/or in Leachate Collection System
 Inspect Leachate Collection/Removal System or French Drain
 Repair Leachate Collection/Removal System or French Drain
 Temporary Cap
 Waste Removal (See Soils Section of this table)
 Interim Groundwater Measures (See Groundwater Section of this
 table)
Run-off/Run-on Control (Diversion or Collection Devices)
Temporary Cover
Waste Removal (See Soils Section of this table)
Interim Groundwater Measures (See Groundwater Section of this
table)
Sampling/Analysis; Disposal
Run-off/Run-on Control (Diversion or Collection Devices)
Temporary Cap/Cover
Delineation/Verification of Gross Contamination
Sampling and Analysis
Interceptor Trench/Sump/Subsurface Drain
Pump and Treat; In-situ Treatment
Temporary Cap/Cover
Overflow/Underflow Dams
Filter Fences
Run-off/Run-on Control (Diversion or Collection Devices)
Regrading/Revegetation
Sample and Analyze Surface Waters and Sediments or Point Source
Discharges

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              Table 1. (Continued)
               Gas Migration Control

                 1.

               Particulate Emissions

                 1.
                 2.
                 3.

               Other Actions

                 1.
                 2.
                 3.
                 4.
                 5.
                 S.
Barriers/Collection/Treatment/Monitoring
Truck Wash (Decontamination Unit)
Revegetation
Application; of Dust Suppressant
Fencing to, Prevent Direct Contact
Sampling Off-site Areas
Alternate Water Supply to Replace Contaminated Drinking Water
Temporary Relocation of Exposed Population*
Temporary or Permanent Injunction"
Suspend or Revoke Authorization to Operate Under Interim Status*
              'Model language not included in Interim Measures Guidance - Interim Final.
References

U.S. EPA.  1988a. RCRA Corrective Action Plan -
Interim Final EPA/530- SW-88-028, OSWER 9902.3,
Office of Solid  Waste and Emergency Response,
Washington, D.C., June 1988.
                U.S. EPA. 1988b. RCRA Corrective Action Interim
                Measures Guidance - Interim Final EPA/530-SW-88-
                029, OSWER 9902.4, Office of Solid Waste and
                Emergency Response, Washington, B.C., June 1988.

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                                          Chapter 2
             Engineering Considerations  in the Facility Investigation
If the RFA or other information has indicated a
release  of hazardous constituents, then from the
owner/operator's perspective, the Corrective Action
process truly begins. The first step in the process, the
RCRA Facility Investigation  (RFI), is  directed
toward development of the engineering information
about the site necessary to permit selection and
evaluation of remedial  alternatives. The main
engineering thrust of the RFI is the characterization
of site conditions by defining the nature and extent of
the problem.

The data collection efforts for site characterization
may be expensive  and time consuming. Certain
additional data will be needed to evaluate  potential
Corrective Action options.  Therefore, it is postulated
that if a preliminary screening of possible Corrective
Action options is made before data collection for site
characterization begins, the  data necessary  to
evaluate candidate Corrective Action options can be
collected concurrently with the site characterization
data.  For example, the nature of the identified
release,  as well as the owner/operator's knowledge of
hazardous materials used in the past, can give some
indication of the  media contaminated  and the
possible type(s)^ of contamination. Such information
gives the engineer guidance in identifying  potential
Corrective Action technologies.  Furthermore,
because  the time normally required to conduct the
RFI can be as long as 24 months; lab, bench and pilot
tests can be conducted to confirm the applicability of
candidate technologies and to develop system design
information, if deemed appropriate.

Design of the RFI should  incorporate the following
considerations:

•  Both containment and treatment may be options;

•  Different  options may be selected t-o address
   different units;

•  At any given  unit/area,  a combination  of
   technologies (e.g.,  treatment train) may  be
   needed to fully address the problem.

Identification of what contaminants are  in what
media is only part of the  objectives of the RFI.  In
addition, treatability information is required which
addresses the physical/chemical properties  of the
contaminated media.

From an engineering standpoint, the initial step in
the RFI would be to collect historical information
about past practices to provide insight into the
possible source(s) of the release, the type and
quantities of releases, and potential pollutant
migration pathways. The next step would be to
identify possible technologies which may be needed to
halt the migration of the pollutant and to remove
and/or treat the contaminants in the various media
(i.e., soil,  groundwater,  etc.)  in which the
contaminants are found. Through identification of
what is known about the site and what possible
Corrective Action and/or containment scenarios
might be needed for cleanup, a plan can be developed
to fill the data gaps during the RFI. This chapter is
directed toward  the following RFI engineering
activities:

•   Pre-investigation identification  of candidate
    treatment options for containing and/or treating
    contaminants;

•   Field diagnostic tools which can be  used to
    characterize the site;

•   Bench- and pilot-scale study considerations.
Pre-lnvestigation Evaluation of Corrective
Measures Technologies

During the RFI stage of a Corrective Action program,
only limited information about the site and waste
may be available. Some historical data about the
facility and its past practices and operating
conditions may be developed from plant records. In
addition, the RFA may provide some information
about the contaminants and contaminated media.
Because such information is limited, only general
classes of treatment technologies can be identified
initially .(e.g., the material  is organic, so  thermal
processes might work). Such identification of general
treatment options is helpful in planning, since the
data  collection for  site  characterization and

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treatment  selection  can  be  dealt  with
simultaneously. This approach makes the fi|eld
sampling program more cost effective and efficient.

Strategy for Containment Selection:
Early in the Corrective Action process, a decision
may be made concerning whether or not containment
is necessary to protect human  health and  the
environment (HHB). If the release or threatened
release presents danger to HHE, immediate action
must be taken to halt migration. Under  these
circumstances, actions termed "Interim Measures"
may be required, and  excavation or containment
measures may be directed by the regulatory agency.
However, the Owner/Operator  will be responsible for
their implementation. In the event that containment
is not required as an interim measure, containment
may still be needed as part of  the overall Corrective
Action to halt the pollution migration if wastes or
contaminants are to be left on-site.

Based on the existent site information, the questions
which need  to be answered to determine if
containment is needed are:
    In what medium is the contamination located?
    What is the source of contamination?
    What are pollutant migration pathways?
    What are the potential receptors?
    Can the contamination be contained?
Once the medium and a general understanding of the
chemical composition of the waste or contaminant is
known, a number of containment alternatives can be
identified. Table 2 presents the general classes  of
containment technologies for various contaminated
media along with  data needs for technology
evaluation. Table 3 presents a summary of important
geological information required as part of the dat|a to
be collected to support selection of containment
technologies.


Strategy For Treatment Selection
The purpose of treatment is to alter the function,
form or quantity of the waste, or media contaminated
by the releases, by changing its mobility, its volume,
or its toxicity. The hierarchy of hazardous waste
management establishes that a change (reduction) in
toxicity is the main treatment objective. The next
level of acceptable objectives is providing a change
(reduction) in mobility. The least desirable strategy,
other than storage, is producing a change in volume,
unless producing that  change will facilitate
treatment by another means. The general options for
treatment based on these alterations are shown  in
Figure 1.

If the primary intent is to detoxify the waste, then the
characteristics of the waste which make the waste
hazardous (and whether the contaminant is organic
or inorganic) become issues.  Accordingly,  the
questions then become the following:

•  Is it toxic?
•  Is it reactive?
•  Is it corrosive?
•  Is it ignitable?

Table 4 allows a generic identification of the various
technology options suitable for treating wastes based
on their hazardous characteristics and physical form.
Table 4 also identifies the kinds of data which must
be collected to perform a valid evaluation of those
technologies. The physical  treatment data needs for
different media  shown in Table 5 are  typically
required in addition to those presented in Table 4.

Field  Diagnostic Tools

There  are many  field diagnostic tools available for
characterization of  a contaminated  site.  In the
preliminary site investigation, screening techniques
can be  used to locate  areas of contamination by non-
invasive  methods.  Then in  the  detailed site
investigation, sampling and monitoring techniques
which provide greater quantification of contaminants
can be  focused on those areas identified. As would be
expected, screening techniques  are typically rapid
and qualitative as well as being less expensive than
detailed sampling and monitoring techniques.

Preliminary site investigation (screening) techniques
typically include geophysical  surveys, soil gas
monitoring, surface  water sampling, and limited
groundwater  sampling.  Of fchese,  geophysical
techniques (which measure some physical property of
the soil or contaminant) are useful for locating buried
wastes, contaminated soils and  groundwater.
Screening techniques would not usually incorporate
the drilling of wells for core analysis or groundwater
sampling.

Detailed sampling can include, but is not limited to,
the installation of monitoring well networks. After
the wells have been installed, aquifer  tests are
typically  performed. Once the aquifer  tests are
performed  and  the  aquifer characteristics are
determined, time series sampling  for a  given
contaminant,  or a surrogate, is undertaken.  The
combined results of these efforts provide the basis for
development of a treatment strategy. Modeling can
be used as part of this effort  to help determine the
best technical and most cost-effective techniques to
be used at a site.
 Geophysical Techniques
 Geophysical techniques  can be used for many
 purposes, such as to: (1) map hidden hydrogeologic
 features, (2) map leachate plumes and  zones of

-------
 Figure 1 Alteration of function and data needs.



Volume

















Reduction

Quantity






V
-p






Possible
Technology
Classes

Separation






	 k





Data Needs

Which Chemicals at What
Concentrations?

Phase?
Media?





Mobility






Toxicity






• • t






	 k






Change of

Function




Change of
Chemical
Form





>.






	 k






Technology
Classes
Containment
Solidification

Possible
Technology
Classes
Biological
Thermal
Chemical





	 k










Data Needs

Short/Long Term Risk Areas?
Potential Pathways?
Volume?


Data Needs


Which Chemicals at What
Concentrations?
Phase*^
Media?

Table 2. Containment/Recovery Options and Data Needs by Media

Principal Option
for
Containment/
Recovery
Soils
Excavation
Vacuum extraction
Temporary cap/cover
Hydraulic modification
No action
Groundwater
Groundwater pumping
Subsurface drains
Hydraulic barriers
Low permeability barriers
No action
Surface Water/Sediments
Overflow/underflow
containment (i.e. oil booms)
Run off/run on control
Diversion/collection
No action
Air
Capping/insulation
Operations modifications
Gas collection/removal
No action
 Data needed
Soil stratigraphy
Soil hydrology
Surface topography
Engineered features
Chemical composition of
contacted soil
                                    Subsurface soil conditions
                                    Aquifer properties
                                    Geochemical environment
                                    Hydrogeologic setting
                                    Chemical composition of
                                    contaminated plume
Climatic conditions
Geographic conditions
Surface water category
Hydrogeologic setting
Chemical composition of
surface water
Climate
Site-specific weather conditions
Site topography
Physical features
Chemical composition of  waste
contamination where electrical conductivities vary
markedly from background levels, (3) locate trenches
in which wastes may have  been buried, and (4) to
locate and define  buried  metallic objects.  Such
studies are  generally less expensive  than well
installations. (This includes  the  costs  for
development, maintenance, sampling and priority
pollutant analyses).  In some geologic settings,
geophysical  investigations are the  most  suitable
method for investigating groundwater flow paths.
When a geophysical investigation points to a possible
geologic anomaly or otherwise unrecognizable
feature (natural or  man-made), one or a few
appropriately sited wells  can be drilled to  examine
the subsurface directly;  this saves  the  often
unnecessary  and expensive task of drilling many
wells on a grid system to  investigate the  subsurface
geology of the site. Geophysical techniques include
                                       Ground Penetrating Radar (GPR), Electromagnetic
                                       Conductivity (EM), Electrical Resistivity Surveys, or
                                       Seismic Surveys.

                                       It is important to understand that any geophysical
                                       method which is  successful at one site may or may
                                       not have the same success at another site. There are
                                       many variables  associated with all geophysical
                                       techniques as presented in Table 6. Someone with the
                                       experience to know the limitations of each of the
                                       techniques should be consulted prior to developing a
                                       large geophysical reconnaissance program.


                                       Ground Penetrating Radar:

                                       This technique uses high-frequency radio waves
                                       sensitive to interfaces between materials with
                                       differing electrical conductivities. These waves are

-------
Table 3. Summary of Important Geologic Information (EPA 540/G-85/002)
                                                                          Appropriate Collection Methods
      Information Needed
    Purpose or Rationale
          Primary
        Secondary*
 Structural Features:

   •  Folds, faults
   •  Joints, fractures,
      interconnected voids

 Stratigraphic Characteristics:
   •  Thickness, areal extent,
      correlation of units,*
      extent (horizontal and
      vertical) of aquifers and
      confining units
   •  Mineral composition,
      permeability, and
      porosity, grain-size
      distribution, in-situ
      density, moisture
      content
 Groundwater Occurrence:
   •  Aquifer boundaries and
      locations
   •  Aquifer ability to transmit
      water

 Groundwater Movement
   •  Direction of flow

   •  Rate of flow
 Groundwater
 Recharge/Discharge:
   •  Location of
      recharge/discharge
      areas

   •  Rate

 Groundwater Quality
      pH, total dissolved
      solids, salinity, specific
      contaminant
      concentrations
Determine natural flow
barriers or controls
Existing geologic maps, field
surveys
Predict major boundaries,       Existing geologic profiles,
avenues of groundwater flow   pump tests
Determine geometry of
aquifers and confining layers,
aquifer recharge and
discharge


Determine groundwater
quality, movement,
occurrence, productivity
Define flow limits and degree
of aquifer confinement
Determine potential quantities
and rates for treatment  '
options
Identify most likely pathways
of contaminant migration
Determine maximum potential
migration rate and dispersion
of contaminants         ;
Determine interception points
for withdrawal options, areas
of capping
Determine variability of
loading to treatment options


Determine exposure via
groundwater; define
contaminant plume for
evaluation of interception
methods
Existing geologic maps,
observation wells
Laboratory analysis, existing
geologic literature
Existing literature, water
resource atlases
Pumping and injection tests
of monitor wells
Existing hydrologic literature

Existing hydrologic literature
Existing site data, hydrologic
literature site inspection
Existing literature
Existing site data
Remote sensing, aerial
photography, geophysical
techniques '
Borehole logging and
mapping, geophysical
techniques (limited)
Borehole logging and
mapping, geophysical
techniques (limited)
Existing literature


Borehole logging, regional
water level measurements
Water level measurements in
monitor wellis
Hydraulic gradient,
permeability, and effective
porosity from water level
contours, pump test results,
and laboratory analyses
Comparison of water levels in
observation wells,
piezometers, lakes and
streams
Water balance calculations
aided by geology and soil
data
Analysis of groundwater
samples from observation
wells, geophysics
"May be appropriate if detailed information is required or if it is the only method due to a paucity of published data.

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Table 4. Summary of Basic Technologies and Data Needs to Modify the Degree of Hazard of Wastes

     Waste Type	Form	Technology Options     Preliminary Technology Data Needs
      Corrosive
Liquid
Chemical        pH
                Constituent analysis
                Oil and grease content
                Total suspended solids
                Total dissolved solids
       Ignitable
Liquid
Chemical

Biological
                                                  Thermal
                              Gas
                              Solid
                    Thermal

                 Pretreat to get to
                 treatable form by
                  Chemical and
                 Biological means

                    Biological
                                                 Thermal
PH
Constituent analysis
Gross organic components (BOD.TOC)
Dissolved oxygen
Nutrients analysis (NH3, PO4> NO3)
pH
Priority pollutant analysis
ORP

Heat content
Ash content
Halogen content
Moisture content
Heavy metal content
Volatile matter content

Heat content
Halogen content
                Gross organic components (BOD.TOC)
                Nutrient analysis (NH3, PO4, NO3)
                Priority pollutant analysis
                PH

                Heat content
                Volatile matter content
                Ash characteristics
                Ash content
                Halogen content
                Moisture content
                Heavy metals content
       Reactive
Liquid
Chemical


Biological
                              Gas
                              Solid
                                                 Thermal
                    Thermal

                 Pretreat to get to
                 treatable form by
                  Chemical and
                 Biological means

                    Biological
PH
Constituent analysis

Gross organic components (BOD.TOC)
Dissolved oxygen
Nutrients analysis (NH3 , PO4, NO3)
pH
Priority pollutant analysis
ORP

Heat content
Ash content
Halogen content
Heavy metal content
Volatile matter content

Heat content
Halogen content
                Gross organic components (BOD.TOC)
                Nutrient analysis (NH3, PO4, NO3)
                Priority pollutant analysis
                pH

-------
Table 4. (Continued)

      Waste Type
Form
Technology Options      Preliminary Technology Data Needs
                                                   Thermal        Heat content
                                                                   Volatile matter content
                                                                   Ash characteristics
                                                                   Ash content
                                                                   Halogen content
                                                                   Moisture content
                                                                   Heavy metals content
    Toxic-Inorganic
Liquid               Chemical
                               Gas          Pretreatment required
                                              to get to liquid phase
                                               for chemical treat-
                                              ment or solid phase
                                                for solidification/
                                                  stabilization
                               Solid              Solidification/
                                                  Stabilization
                     PH
                     Constituent analysis
                     Oil and grease content
                     Total suspended solids
                     Total dissolved solids
                                     Solubility (in H20, organic)
                                     Solvents, oils, etc.
                                     Size distribution
                                     Constituent analysis
        Organics
Liquid
                                Gas
                               Solid
                                                   Chemical
                                                   Biological
                                                    Thermal
                     Thermal

                 iPretreat to get to
                 |treatable form by
                   Chemical and
                 'Biological means

                     Biological
                                                    Thermal
                     PH
                     Constituent analysis
                     Halogen content
                     Total suspended solids heavy metals
                     content
                     Gross organic components (BOD.TOC)
                     Dissolved oxygen
                     Nutrient analysis (NH3, PO4, NO3)
                     pH
                     Priority  pollutant analysis
                     ORP
                     Heat content
                     Ash content
                     Halogen content
                     Heavy metals content
                     Volatile matter content

                     Heat content
                     Halogen content
                      Gross organic components (BODTOC)
                      Nutrient analysis (NH3, PO4, NO3)
                      Priority pollutant analysis
                      PH

                      Heat content
                      Volatile matter content
                      Ash characteristics
                      Ash content
                      Halogen content
                      Moisture content
                      Heavy metals content
                                                     10

-------
            Table 5. Important Physical Treatment Data Needs

                            Data Need
                 Purpose
             For Solids
                Absolute Density
                Bulk Density
                Size Distribution
                Friability
                Solubility (in H20, organic solvents, oils, etc.)

             For Liquids
                Specific Gravity
                Viscosity
                Water Content (or oil content, etc.)
                Dissolved Solids
                Boiling Pt/Freezing Point

             For Liquids/Solid Mixtures
                Bulk Density
                Total Solids Content
                Solids Size Distribution
                Suspended Solids Content
                Suspended Solids Settling Rate
                Dissolved Solids Content
                Free Water Content
                Oil and Grease Content
                Viscosity

            For Gases
                Density
                Boiling (condensing) Temp.
                Solubility (in H20, etc.)
Density Separation
Storage Volume Required
Size Modification or Separation
Size Reduction
 Dissolution


Density Separation
Pumping & Handling
Separation
Separation
Phase Change Separation, Handling and Storage


Storage & Transportation
Separation
Separation
Separation
Separation
Separation
Storage & Transport
Separation
Pumping and Handling


Separation
Phase Change Separation
Dissolution
sent and received (usually) from the same antenna,
with variations in  the returning signals being
recorded  continuously. The resulting  subsurface
profile shows features such as  bedding, voids and
fractures. There are  depth limits to this technique,
with signal attenuation becoming more important at
depths where subsurface  materials  have low
electrical conductivities, i.e., where pore fluids are
present in quantity. What this means is that optimal
conditions for this technique are sandy or rocky soils
in the vadose zone or bedrock with low permeability
where water is not permanently present. Clay-rich
sediments (which by  their nature retain  water more
than most sediments)  and  otherwise damp  or
saturated sediments will  generally  yield  poorer
results. However,  reliable data are obtainable  in
settings  where pore  fluids  have  a  low specific
conductance, e.g., where significant amounts  of
petroleum products are present.  Ground penetrating
radar gives the highest resolution among the various
techniques discussed  herein, and a radar survey can
be done relatively quickly at hazardous waste sites.
 Electromagentics:
 The electromagnetic method measures  electrical
 conductivity values of subsurface materials. Where
 pore fluids are present, it is their conductance values
 that  are  measured.  A  transmitter emits  an
 electromagnetic field that sets  up induced  eddy
 currents,  which are intercepted by a receiver,
 producing an  output voltage that is related to
 subsurface conductivities. Paralleling the results
 obtained with radar, electromagnetic methods reveal
 changes in soil  conductivity which are normally
 related to pore fluids. For example,  in instances
 where leaking  drums were buried in shallow
 trenches, the contaminated zone contrasted sharply
 with surrounding sediments. Because this technique
 produces data in conductivity units directly, the data
 can be used in the field immediately after the survey.
 This can allow for quick, "best-educated guess"
 decisions if necessary.
                                                   11

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Tablo 6. Geophysical Techniques, Their Application and Limitations
                                             Utilization at Hazardous
    Technique      Technology Description	Waste Sites	
                                                    at Hazardous Waste Sites (Johnson, 1986)

                                                                       Limitation on Application
 Ground
 Penetrating
 Radar (GPR)
 Electromagnetic
 (EM)
 Conductivity
 Seismic
 Refraction (SR)
  DC Resistivity
  Magnotomeby
  (MAG)
  Metal Detection
  (MD)
An electromagnetic
pulse is sent into the
ground. The reflected
pulses are detected by
an antenna held at the
surface of the ground.
Measures the electrical
conductivity of materials
In microohms over a
range of depths
determined by the
spacing and orientation
of the transmitter and
receiver coils, and the
nature of the earth
materials.
Induced compression
waves are reflected at
the interface of the
subsurface elements and
refract differently based
on the properties of the
new medium of
propagation.
Measures the voltage
drop between two
electrodes in the ground
after an electric current
has been put into the
ground between two
other electrodes.
 Measures the intensity
 of the earth's magnetic
 field and local magnetic
 anomalies. By
 electronically filtering out
 the earth's magnetic
 field and nulling the
 instrument, the local
 magnetic anomalies
 created by ferro-
 magnetic objects can be
 qualified.
 MD measures
 instrument responses to
 deposits of ferrous and
 nonferrous metals up to
 10 to 20 ft deep.
In real-time, shallow earth
profiles of dielectrical dis-
continuities related to sub-
surface conditions such as
moisture content, >lithology,
bedding, voids, fractures,
man-made  objects. Can be
used to detect buried plas-
tic containers and areas of
excavation  boundaries.


Delineates  areas of soil and
groundwater contamination
and the depth to bedrock or
buried objects. Surveys to
depths of 50 to 100 ft are
possible.
Estimates the depth of
bedrock, rock strength
(density), depth to
saturated soil or rocks and
soil layering in general.
Used to locate fractures in
the bedrock that act as
conduits for the
contamination in otherwise
impervious strata.
 Metal can be detected to
 depths up to 60 ft
 Frequently a gradiometer,
 basically two
 magnetometers ih one with
 the sensors at different
 levels, is more efficient than
 the single sensing unit.
 Detection of high-density
 deposits in shallow depths.
 Good inexpensive
 preliminary survey tool.
• Adverse soil conditions - Radar waves will not effectively
 penetrate damp, low-resistance clay or other conductive
 material.
• Improper antenna - Several frequencies should be tried before
 selecting the optimum frequency and antenna.
• Adverse surface conditions - Grooming of the surface may be
 required. Long grass and rough ground cause problems with
 radar penetration and patterns. Surface and subsurface metal
 can distort the GPR record.
• Improper calibration - Depth is difficult to derive from a single
 antenna receiver unless a specific target can be identified.

• Power lines, underground cables, transformers and other
 electrical sources severely distort the measurements.
• Low resistivities of surficial materials makes interpretation
 difficult. The top layers act as a shunt to the introduction of
 energy into lower layers.
• Capabilities for defining the variation of resistivity with depth are
 limited.
• In cases where the desired result is to map a contaminated
 plume in a sand layer beneath a surficial  clayey soil in an area
 of cultural interference, or where chemicals have been spilled
 on the surface, or where clay soils are present, it is probably
 not worth the  effort to conduct the suivey.
• Fill  material must be evaluated with extreme caution.
 Substantially more shot locations should be made than needed
 for a conventional survey.
• Industrial sites produce a lot of background noise, and it is
  necessary to utilize sources of energy more powerful than for
  normal suivey work.
• Correlating data from site borings are required to obtain
  meaningful results from interpretations of the data.

• The Wenner array should not be used unless the expected
  ground conditions are fairly simple. The Schlumberger array is
  less sensitive to lateral resistivity variations.
• Meaningful resistivity results cannot be expected on top of the
  area of buried debris (landfill), dry sand, frozen ground, or near
  fences, or railroad tracks and underground  pipes.
• The resistivity survey cannot interpret information from a
  horizon  beneath  an aquifer.
• Contour maps of apparent resistivity can be misleading.
  Electrode spacing should, not be considered to have a linear
  relationship with  depth of penetration.

•The most effective survey lines orient N/S.
• Readings every 10 ft are needed on survey lines 30 ft apart.
• Surface ferrous items should be noted.
• Many anomaly patterns can exist due* to  other site  activities
  than waste disposal.
• Anomaly patterns of a gradiometer are more difficult to interpret
  than those of the magnetometer.    :
 • Background conductivities greater than 40 millimhos/meter
  impairs results.
 • Wet clay soils impair resluts.
                                                                  12

-------
Because most groundwater contamination problems
involve anionic/cationic species or organic chemicals,
a change in background conductance levels will occur
when a significant amount of contaminant is present
in the subsurface. In the case of polar species (such as
heavy  metals, nitrates, chlorides, and other
electrolytes) the specific conductance will, in most
settings, be increased greatly over background levels.
With organic contaminants such as nonpolar
chlorinated solvents, specific conductance levels will
decrease. In either case, an electromagnetic survey
will commonly be able to detect the  contaminant
plume,  define its  boundaries and, in some cases,
indicate the flow direction.

Resistivity

These surveys measure the  electrical resistivity of
subsurface materials, which is just the opposite of the
electromagnetics survey. As one  might expect,  the
advantages and disadvantages of each method  are
not the same.  Resistivity methods use a  pair of
electrodes  at  the  ground's surface  to set  up an
electrical current in the subsurface, and the resultant
voltage is measured by a second  pair of electrodes.
Resistivity is then calculated using  site-specific
variables in a standard equation. The effectiveness of
a resistivity survey is basically dependent on pore
fluid composition, as with electromagnetics, and the
results can be used in a similar way. For example, the
survey can be used to define the boundaries  of a
contaminant  plume  or to  establish subsurface
stratigraphic relations (Figures 2a and 2b).
                                          Figure 2b   Subsurface stratigraphic relationship
                                                    (Universal Oil Prod., 1972).
 Figure 2a
v- Electric
\Timer
Boundaries of a contaminant plume (Universal
Oil Prod., 1972).

                    Shock Points at
                     10' Intervals
           Water-Bearing
           '-  Sand
                X  .' '-.  .(
                         Bedrock
A comparison of resistivity and  electromagnetic
techniques (resistance versus specific conductance)
shows that resistivity surveys are slower because the
technique is necessarily limited to  measurements at
the fixed electrode points, which must be moved for
each new survey. Electromagnetic surveys are not
limited by fixed points. Also, certain applications of
resistivity methods are best suited for sites where the
                                             0.040
                                             0.030
                                             0.020
                                             0.010
                                                                            V3 = 8,300 fps
                                                 0  10  20  30  40  50  60  70  80 90 100
                                                             Distance in Feet
stratigraphic column is fairly uniform over the entire
area. Resistivity surveys, however, are  generally
more effective than electromagnetics in profiling
vertical variations in the subsurface. Furthermore,
results of resistivity can be  evaluated in the field
qualitatively or semi-quantitatively. An additional
capability of resistivity is that a first approximation
of lithologic compositions can be made, particularly
when outcrops are lacking in an area and wells are
widely separated or absent altogether.


Seismic Refraction

This technique measures the travel time or velocity
of seismic waves to map depths to and thicknesses of
particular stratigraphic units or other significant
layers (e.g., the water table or the base of landfills
and trenches) in the subsurface. This is not the same
as the seismic reflection technique commonly used in
oil and gas exploration.  The  seismic reflection
technique is ineffective at the relatively shallow
depths  in which contamination occurs at most
hazardous waste sites. Seismic waves are sent out by
introducing energy  at  the surface and recording
direct and/or refracted waves with geophones  spaced
at regular intervals (Figures 3a and 3b). This method
is inherently susceptible to severe disturbance by
stray vibrations, which can be set up by nearby
footsteps, cars, trains, etc., and the investigator must
be aware of the potential problems such vibrations
may cause in the data.

Seismic studies are very useful when information is
lacking on subsurface  stratigraphy, or when the
depth to bedrock, the water table, a particular bed or
formation, or some other layer in the subsurface must
be determined without drilling.  Seismic lines  can be
set up to produce stratigraphic cross sections and
they can be  a very useful "non-invasive"  inves-
                                                 13

-------
tigative technique, particularly if correlated with a
core-measured section or geophysical well log. The
lack of "hard" stratigraphic data from a core, well log,
etc., means  that  the  interpretation of the  "soft"
seismic data is much more subjective. This may not
be a problem in a small study area, but when the goal
is subsurface stratigraphic interpretation  over a
large area, the results would probably be considered
speculative until a well was drilled and logged or an
outcrop measured, and this stratigraphic information
was convincingly correlated with the seismic data.
Once again, note the importance of mapping the site
geology to determine field relations of the various
strata present. Without this information, much of the
interpretation of information gathered from seismic
studies is necessarily speculative.               :

 Figure 3a    Cross-section of seismic refrac*'on measuring
            technique (Zhody, 1974).
                            Potential Electrode •
          Current
          Source
          -W«—
Milliommeter
                        Potentiometer
                            L-*	
                 Current
                 Electrode
 *f*****l£ Ui»« MM"I »• -t w.«l»!.»«.•. '	^M^IMMgpMr**.
  ;.—^lh£>-.-i^c^..^^^?^-;j^v:-_=j-=£F-^-^~i; v
  • Moist Silt & Clay  J?fe>fSr-lr*"^ai^X>. r;
 < (Low Resistivity) \$£z^SJK*. wfc^.=-z.-^.,
    	  -
               L.x--N
               *..-»7Xi*-v«

          Resistivity of This •
          Region Measured

           ^^
                                        ;^V£>
   •Xv>if«J Sand & Gravel
   TfT^.y;- (H'flh resistivity)
 Figure 3b   Log of seismic refraction results (Zhody,
            1974).
              Honzontal Distance in Meters
           100     200      300      400
                   500
    0   200   400  600  800  1000 1200  1400  1600
    West        Horizontal Distance in Feel         East
                             Soil Gas Monitoring
                             VOCs on the "surface" of groundwater volatilize into
                             the voids in the soil above the groundwater. Soil gas
                             collection and  sampling procedures have been
                             developed that are simple and quick to implement
                             (Lappala, 1984; Quinn, 1985; Nadeau', 1985). In one
                             method as shown in Figure 4, a small diameter (1-in.)
                             steel probe is inserted to a depth of 3 feet. A vacuum
                             pump pulls the  VOC that is present between the
                             interspaces or voids  of the soils into a sample  tube.
                             The sealed tube is taken to a laboratory for analysis
                             by Gas Chromatography (GC). The sample train  is
                             decontaminated before use in the next probe hole by
                             pumping ambient air through the system. A portable
                             photoionization detector (PID) gas chromatograph
                             can be used in the field prior to putting the sample
                             into the collection tube.*  By first passing a sample
                             through this device, a quick  determination of the
                             presence of VOCs can be made. If there is no reading,
                             then no sample need be analyzed in the laboratory.

                             Figure 4.    Soil vapor probe and sampling train (Nadeau,
                                        1985).
                                                                  - Air Sampling Bag
                                                                                            Vacuum
                                                                                            Pump
                             As shown in Figures 5a, 5b, 5c and 5d, the soil gas
                             sampling procedure can quickly produce isopleths of
                             VOC concentrations over a large site and indicate
                             possible source areas. While not exactly analogous to
                             the VOC concentrations in groundwater, the results
                             can be utilized to develop a borehole and monitoring
                             well  program with a minimum number of wells
                             because of this prior knowledge of the site conditions.
                             The soil gas sampling procedure is low cost, produces
                             low site disturbance and can be used at sites with
                             difficult access.

                             Detection  limits  of 0.0001 to  0.01  mg/P in. soil
                             samples and 0.1 to 1.0 mg/€ in water samples have
                             been reported. Lappala (1984) reported the results of
                             repeated  sampling on  successive  days  at  a
                                                   14

-------
southwestern United States site using these soil gas
sampling techniques. The results of successive days'
samples  showed no significant difference  by
Student's "t" Test. However, Karably (1987) reported
significant variations  in  soil gas sample point
readings (i.e., magnitude of VOC detected) over an
extended time period caused by environmental
variables. However, the general trend of contaminant
levels and plume geometry were roughly the same.
Soil gas concentrations were found to be affected by
temperature and infiltrating groundwater.

A second factor affecting the repeatability of the soil
gas sampling techniques was  the length of time to
draw the sample at each station.  Karably (1987)
reported that results of repeated sampling at the
same station suggest that a specific volume of soil gas
must be evacuated to obtain a representative sample,
and that this volume would differ among hazardous
sites. This required volume would need  to  be
determined at each site as part of the sampling
protocol. Results and effectiveness have been found to
be sensitive to repeated  spill incidents on the same
site and to fluctuations  of the groundwater  table.
Sites with tight, saturated clay layers or an expected
contaminated  layer below a clean layer  of
groundwater are not good applications for soil gas
sampling (Lappala, 1984). A sampling probe length
of 3 feet has been used on sites  with groundwater
down to 36 feet, while a length of 10 feet is needed for
groundwater  down  to  100 feet. If the  detected
concentration decreases with depth, then the source
of the VOC is a surface spill. If the concentration
increases, this indicates that the  VOC is on the
surface of the groundwater. The sampling procedure
has limited usefulness for deep groundwater (75 to
100 feet).

For air sampling of unknown contaminants,  a
multistage tube was  developed to provide a  quick
profile of organic compounds (Turpin,  1984). Solid
sorbent media require minimal processing to produce
a suitable sample for injection into GC/MS analytical
equipment, a  rapid qualitative  and  quantitative
device for characterization of unknown mixtures.
This procedure reduces the  number of air samples
needed,  improves turnaround time, and identifies a
wide variety of chemicals in the  screening process.
The sample is collected in a two-stage tube consisting
of Tenax-GC packing in the first tube  and
Chromosorb® 102 sorbent in the second. Some
chemicals such as tricresyl phosphate, isopropyl
alcohol,  chlordane, Aroclor 1254, and naphthalene
were not collectible by this tube configuration.


Use of Surrogates
During a preliminary investigation, much of the
expense associated with analytical activities can  be
reduced  by using surrogate or good indicator
parameters. These are typically nonspecific.
 Examples would be: total organic carbon, total
 organic halogens, specific conductance or, if dealing
 with gases, organic volatile measurements. It should
 be emphasized that these analyses measure a class or
 a group of compounds and may not directly quantify
 the specific compound or contaminants of concern.
 Care must be  exercised when  correlating these
 nonspecific measurements with the total movement
 of the contaminant.


 Core Sampling

 To make the most of monitoring well installations, it
 should be decided if continuous coring with core
 recovery should be performed during well drilling
 activities. The study of cores is the best  way to
 examine rocks  in the subsurface, and if there are
 unresolved questions about porosity, hydraulic
 conductivity, fracturing, etc., the detailed lithologic
 log produced from core  logging will often provide
 answers. Cores give a more complete picture of the
 subsurface geology and contaminant location than do
 cuttings alone, and therefore, coring is preferred.


 Monitoring Well Networks

 Pumping tests or single well tests are probably the
 most utilized tool to determine the aquifer properties.
 There are a number of different  type  tests, but as
 with any other type of testing program, selecting the
 sampling point(s) is critical in order to obtain good
 results. An effective preliminary survey can produce
 significant cost savings by specifying the optimum
 locations for a minimum number of required wells.
 Before any site-specific groundwater sampling is
 done, soil  and  waste characterization should be
 completed.

 When groundwater contaminant plumes  are
 suspected of having significant  depth as well as
 lateral distribution,  a three-dimensional array of
 monitoring points  is  needed  to  identify and
 characterize such plumes. Thus,  groundwater data
 must be obtained from a number of different locations
 and  from a number of different depths at each
 location. As a  result, either a  large number of
 drillholes are  required, each with separate
 instrumentation installed, or instruments must be
 combined and installed at multiple levels in each of a
 smaller number of drillholes.

 Several downhole sampling devices have been
developed to sample at discrete and  multiple levels
 within the well. Discrete sampling can be utilized to
 identify the location for the well screening to assure
 extraction of the contaminant during pumping. The
 sampler can  be  lowered  into a  borehole  to
increasingly lower depths until the proper level is
identified. The sampler is then removed and the well
is developed for extraction. If the well were being
developed as a monitoring well, then the sampler can
                                               15

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Figure 5.    Comparison of TCE and TCA concentration distribution by groundwater and soil gas samples, southwestern U.S.
             study (Lappala, 1984).
                 Plant —'     «- Solvent Sump

                    Log of TCE in Groundwater

                            Figure 5a.
                                    Plant
                                                                                       - Solvent !3ump
                                         Log of TCE in Soil Gas

                                               Figure 5b.
                 Plant
                              V
Solvent Sump
                                                                    Plant
                                                                                        Solvent Sump
                      Log of TCA in Groundwater

                            Figure 5c
                 Legend:
                 •  Monitoring Well
                 *  Soil Gas Probe
                 r-f 3.1 Log of TCE or TCA Concentration in Groundwater
                 /-x 3.1 Log of TCE or TCA Concentration in Soil Gas
                                           Log of TCA in Soil Gas

                                                Figure 5d.

                                              100      200 Meter
                                                           16

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be left in place. A multiple level sampler can be used
to take many samples over the depth of the well
without having to be  moved  if such sampling is
required.


Conceptual Model
Upon completion of both the preliminary and detailed
site investigation,  a  conceptual  model can be
prepared. A conceptual model  is essentially a site
model which includes all of the information that has
been acquired for the site from both preliminary and
detailed investigations,  as  well  as  other
investigations not directly related to the site. The
conceptual  model can be anything from simple
diagrams to detailed computer simulations,
depending upon the complexity of the site. The model
must be continually updated  to include  new
information as it is developed.

Once the conceptual  model is operating, it can be
utilized to help develop a technically sound, cost-
effective recovery and  treatment system. Potential
uses for a conceptual  model include provision  of
continual updates of project developments, provision
of a yardstick to measure what has been done and
what needs to be done, and helping prioritize  areas
for Corrective Action. Ultimately, the principal use
for a conceptual model is to help determine  what
Corrective Actions or alternatives are applicable to
the site.

Laboratory and Bench-Scale Studies

Bench- or pilot-scale studies are necessary to
demonstrate the ability of a technology to effectively
treat a  specific waste.  Waste characteristics vary
from site to site and  because of this, the effect of a
treatment technology with that particular waste may
not be known, given the site-specific  factors and
conditions. Also, the proposed treatment technology
may be new or unproven.

Thus, bench or pilot  studies are necessary to  avoid
technology misapplication in the field.  The loss  of
time in treatment or the requirement to provide
additional treatment for the waste is very expensive.
Therefore, the relatively small costs and time needed
for these studies make them useful tools in treatment
selection. Bench-scale treatability studies for
demonstrated technologies can cost between $10,000-
$50,000 and take up to 6 weeks.  Demonstrated
technologies are those  for which the major design
parameters  and treatment efficiencies are well
understood. Innovative (and some  biological
processes) will require substantially more time (4-16
weeks) and money ($25,000-> $200,000). These are
estimates, and actual time and costs are  going to
depend on  what kind of technology is under
consideration.
Pilot-scale studies for demonstrated technologies can
cost from $25,000  to more than $100,000 and
typically require  2-12 weeks. For innovative
technologies, the cost for pilot testing can start  at
$100,000 and exceed $1,000,000 and require 3 to  12
months.

Aside from size considerations,  the primary
difference between bench-scale and pilot-scale work
is that bench-scale tests are conducted in the
laboratory; pilot-scale testing is usually carried out
on the site. Pilot tests are subject to a whole range of
problems, such as siting, health and safety, obtaining
clearances, installation and operation. However, the
data obtained from pilot-scale tests are much more
appropriate and useful because they reflect what is
actually occurring in the field.

The choice of the kind of testing (bench or pilot-scale)
to be performed is going to hinge on the balance
between the level of certainty that the technology is
going to work (and be effective for the site) against
the risk of failure if the technology does not work for
the unique mix of contaminants and contaminated
media (air, water, soils, sediments) found at that site.
The risks of failure include the cost and time needed
to perform another  test  or to implement another
technology if the first one selected fails. Obviously,
pilot-scale studies may not be needed if there is a
high level of certainty that the particular technology
will work (i.e., there is a low risk of failure).  Pilot-
scale  studies also may be unnecessary if there  is
going to be very little cost or time penalty for
identifying a new treatment system, given failure of
the first. On the other hand, if there is a low level of
certainty  that the technology is appropriate and
there is a very high risk of failure, one needs  to
carefully consider that it may be more prudent  to
spend the time and money for bench-scale testing.
Pilot-scale testing, without prior bench-scale testing,
should be  employed only  when there is a moderate
level of certainty that the technology is going to be
effective and there is only a moderate risk of failure.

References

Johnson Division-Universal Oil Products Company,
Groundwater and Wells, St. Paul, Minnesota,  1972,
p. 177.

Johnson, W. and P. Johnson. "Pitfalls of Geophysics
in Characterizing Underground Hazardous Waste,"
In:  Management of Uncontrolled Hazardous Waste
Sites  Proceedings, Hazardous Materials Control
Research Institute, Washington, D.C., p. 227-232,
1986.

Karably,  L.  and   K.  Babcock.  Effects of
Environmental Variables on  Soil Gas Surveys In:
Superfund  '87,  The 8th  National Conference
                                                17

-------
Proceedings, Hazardous Materials Control Research
Institute, Washington, D.C., 1987.
Lappala,  E. and  G. Thompson. Detection of
Groundwater Contamination by Shallow Soil  Gas
Sampling in the Vadose Zone and Applications. In:
Management of Uncontrolled Hazardous Waste Sites
Proceedings, Hazardous Materials Control Research
Institute,Washington, D.C., 1984.
Nadeau, R., J. Lafornara, G. Klinger and T. Stone.
Measuring Soil Vapors for Defining  Subsurface
Contaminated Plumes. Management of Uncontrolled
Hazardous Waste Sites Proceedings,  Hazardous
Materials Control Research Institute, Washington,
D.C.,1985.
Quinn, K., S. Wittmann and R. Lee. Use of Soil Gas
Sampling Techniques  for  Assessment  of
Groundwater Contamination. In:  Management of
Uncontrolled Hazardous Waste Site Proceedings,
Hazardous Materials Control Research Institute,
Washington, D.C., 1985.

Turpin, R., K. Vora, J. Singh, A.  Eissler, and D.
Stranbergh. "On-Site Air Monitoring Classification
by the Use of a Two-Stage Collection  Tube,":
Management of Uncontrolled Hazardous Waste Sites
Proceedings, Hazardous Materials Control Research
Institute, Washington, D.C., 1984.

Zohdy, A., G. Eaton, and D. Mabey. Application of
Surface Geophysics to Groundwater Investigation,
Techniques of Water Resource Investigation, Book II
Chapter  Dl, U.S. Government Printing Office,
Washington, D.C., 1974, p.14.
                                               18

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                                         Chapter 3
                                  Containment Options
 If hazardous wastes or hazardous constituents are
 found to be migrating from a RCRA-regulated
 facility, an initial response might be directed toward
 implementation of methods to control their spread.
 Once the site  investigation provides sufficient
 information about the nature and extent of the
 contamination and the medium in which the
 contaminant is located, actions to limit the spread of
 the contaminant can be developed, if  deemed
 necessary. Note that the containment technology
 selected depends upon the medium in which the
 contaminant is found and the general containment
 options available for common situations encountered
 are shown in Figure 6. These situations include
 contaminated groundwater and gaseous emissions
 from landfills or surface impoundments.

 Groundwater Containment

 Contaminants from a hazardous waste site can enter
 the groundwater system through  a variety of
 mechanisms: (1) surface water infiltration, (2)
 groundwater passage through the waste, and (3)
 liquid waste flow through permeable soil. Control of
 contaminant migration involves containment of the
 contaminated groundwater  plume and the
 prevention of further dissolution of contaminants by
 water entering the waste  area.  Infiltration of
 rainwater to the  contaminated medium can be
 controlled by capping and surface water diversion
 techniques. A more difficult problem arises when
 trying to contain the movement of  uncontaminated
 groundwater through a waste or of a plume of
 contaminated  groundwater. However, before a
 specific containment strategy can be selected and
 subsequently located in the field, it is important to
 have a good understanding of the hydrogeologic
 setting and the  subsurface behavior of the
 contaminants.

With  an understanding of the site geology and
 hydrology and the behavior of the contaminants in
 the subsurface, the selection of containment/recovery
technology can begin. Typical ways to contain and/or
recover contaminated groundwater  plumes include
groundwater pumping, subsurface drains and barrier
walls. Barrier walls  are a passive option typically
aimed at containment whereas groundwater
  Figure 6. Containment options.
   Surface water diversion and
   capping can be used to prevent
   further infiltration of rainwater or
   runoff.
pumping and subsurface drains can be used to control
pollutant  migration as  well as  to extract
contaminated groundwater  for subsequent
treatment.


Groundwater Pumping

Groundwater pumping can be used  to manipulate
and manage groundwater for the  purpose  of
removing, diverting, and containing a contaminated
plume or for adjusting groundwater levels to prevent
plume movement.  For example,  pumping systems
consisting of a series extraction wells located directly
down-gradient from a contaminated source  can  be
                                              19

-------
used to collect the contaminated plume. Water can
also be injected into the subsurface to move the plume
away from an area that must be protected, such as a
domestic drinking water source (Figure 7a and 7b).
The success of any contaminant capture system based
upon pumping wells is dependent upon the rate [of
groundwater flow and the rate at which the wellj is
pumped.  Thus, the zone of capture for the pumping
system must be established.                     :

Figure 7a.   Containment using extraction wells (U.S. EPA,
          1985).
                                    Domestic
                                      Well
               Extraction Wells
               with Radium of
                 Influences
Figure 7b.
Plume diversion using Injection wells (U.S. EPA,
1985).
        Injection
          Wells
                         Domestic Wells
 Corrective Action Application
 The Fairchild Camera and Instrument Corporation
 site in South San Jose, California, proved to be a
 complex and difficult groundwater contamination
cleanup action (U.S. EPA, January 1987).  Over
43,000 gallons of organic chemicals were lost into the
•soil, contaminating four aquifers? beneath  the site.
Groundwater in the shallow aquifers was initially
contaminated  by the chemicals. Subsequently,
contaminants migrated into the lower  aquifers
through interconnecting sand beds, existing wells,
and slow seepage through separating strata. The first
action taken for  plume  containment  was the
installation of an extraction well to create  a zone of
influence  to draw  the plume back.  The initial
pumping rate was 500 gpm, but this was increased to
1500 gpm when the lower rate failed to contain the
plume spread. To further control the spread of the
plume, three rows of extraction wells were installed
near the source of the contaminant.  The combined
pumping dewatered two  aquifers, but  left the
contaminant behind in  the unsaturated soil.
Subsequently, contaminants continued to migrate to
lower aquifers. Finally, the source  was contained
with a 3500-ft long, 70 to 140-ft deep, 3-ft wide slurry
wall.

Subsurface Drains
Pumping  techniques  represent an aggressive
approach which requires ongoing maintenance and
operation  throughout the  life  of the Corrective
Action. By contrast, subsurface drains (and barrier
walls, described below) represent a passive design
which do  not  require a  high level of ongoing
maintenance. Subsurface drains are  most useful in
preliminary containment applications for controlling
pollutant migration while a final treatment design is
developed and implemented. They  also provide a
measure of long-term protection  against residual
contaminants following conclusion of treatment and
site closure.

 Subsurface drains are essentially permeable barriers
designed to intercept the groundwater flow. The
 water must be collected at a low point and pumped or
 drained by gravity to the  treatment  system (Figure
 8). Subsurface  drains can also be  used to isolate a
 waste disposal area by intercepting the flow of
 uncontaminated groundwater before  it enters into a
 contaminated site.


 Corrective Action Application
 The use of a drain  system permits the  quick
 construction of a collection/removal system  which
 also serves as a barrier for leachate from large,
 shallow sites. At the Sylvester hazardous  waste site
 in  Nashua, New Hampshire,  a  groundwater
 interception and recirculation system  was installed
 as a method to retard further spread of the leachate
 plume until a remedial  cleanup action could be
 implemented. The system was operated for 1 year
 until a containment wall and cap were constructed
 over the 20-acre site (McAneny, 1985).
                                                 20

-------
  Figure 8. The use of subsurface drainage to contain a leachate plume (U.S. EPA, 1985).
                                        Waste Disposal Site
                                               Contaminated   "%.
                                             Groundwater Plume t?
                               Groundwater Flow
                                   Direction
                                                                            Map View

                                                                   Subsurface Drainage
           5 ^3-'- -" '

            rfT> /
                   Collected
                 Groundwater is
                  Pumped into
                Treatment System
                                                                          Cross Section
                                    Waste Disposal Site
                                                                   Original Water
                                                                      Table
                                 Contaminated
                               Groundwater Plume
Barrier Walls
Low permeability barriers are used to direct the
uncontaminated groundwater  flow around  the
disposal site or to prevent the contaminated material
migrating from the site.  Figures  9a,  9b and 9c
illustrate typical configurations  for barrier walls.
Barrier walls can  be  made of a wide  variety of
materials as long as they have a lower permeability
than the aquifer. Typical materials include mixtures
of soil  and bentonite,  mixtures of cement and
bentonite, or barriers of engineered materials (sheet
piling). A chemical analysis of wall/contaminant
compatibility is necessary  to the final selection of
materials.  The installation of a low permeability
barrier usually entails a great deal of earth moving,
requires a significant amount of land area, and is
expensive.  However, once in place, they represent a
long-term,  low maintenance system. Once in place,
active gradient  controls  (i.e.,  pump  and treat)
required by some installations will add to the long
term operating costs of these systems.
 Corrective Action Application

 At one Superfund site, a slurry wall was placed
 around a landfill containing municipal waste and
 industrial hazardous wastes (solid  and liquid). In
 addition to installing the slurry wall, a cap over the
 site was constructed simultaneously.  Due to the onset
 of winter, the capping of the site had to be halted.
 During  the  subsequent  winter months,  an
 extraordinary amount of rainfall was experienced.
 The area within the slurry wall began to  fill with
 water (the bathtub effect). A pumping and treatment
 system had to be installed to reduce and treat  the
 water which collected within the slurry wall. Some
 portions of the slurry wall required repair due to the
 large hydraulic gradient produced by the high water
 levels inside the wall (U.S. EPA, 1987).

 This case serves to point out the  importance of
 maintaining a constant hydraulic gradient  on  the
 inside and outside of a slurry wall. This  can also
become a factor if slurry  walls are used with
groundwater pumping systems (extraction  wells).
Then water must be reinjected to maintain a
                                                 21

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Figure 9a.   Plan of downgradient placement (Spooner et al.,
          1984).                               |
    Groundwater Divide
                                     Extraction
                                      Walls
                                      Slurry
                                      * Wall
Figure 9b.   Plan of upgradient placement with drain
           (Spooner et al., 1984).
 Figure 9o.   Plan of circumferential wall placement
           (Spooner et al., 1984).
   Qroondwater Flow
                                       Slurry Wall
                                    Extraction
                                      Wells
relatively constant hydraulic gradient on both sides
of the slurry wall.

Containment and Control Options for
Gaseous Wastes from Soils

Gaseous wastes may introduce an additional range of
problems which must be addressed in the design of a
containment plan. Gaseous wastes will migrate
vertically or horizontally along: the path of least
resistance. Control systems fall into three general
categories: (1) passive perimeter gas control systems,
(2) active perimeter gas control systems, and (3) ,
active interior gas collection/recovery systems. All of
these systems assume the installation of a cap to
prevent vertical escape of gaseous wastes.


Passive Perimeter Gas Control! Systems
Passive perimeter gas control systems are designed to
alter the path of contaminant flow through the use of
trenches or wells, and  typically include synthetic
flexible membrane liners (FMLs) and/or natural
clays as  containment materials. The membrane is
held in place by a backfilled  trench, the depth of
which is determined by the distance to a limiting
structure, such as groundwater or  bedrock.  A
permeable trench installation functions to direct
lateral migration to the surface, where the gases can
be vented (if acceptable) or collected and conveyed to
a treatment system (Figure lOa and lOb).


Corrective Action Applications
At the Lipari Landfill site in New Jersey, the gas
venting system installed  in 1983  consisted of two
underground 4-inch  (10-cm) perforated PVC pipes
and five vent risers. Two parallel PVC pipes were
installed 200 feet apart prior to cap emplacement
during the period of wall construction and were
placed about 3 feet beneath the finished grade. The
vent risers were connected to the buried manifold
pipes and  consisted of open  pipe installed
perpendicular to the underground pipes  and the
ground surface. Filters were not attached to the riser
exit points (U.S. EPA, 1987).


Active Perimeter Gas Control Systems
An active perimeter gas control system can have any
 of the same configurations as a passive perimeter
 system with the addition of any combination of gas
 extraction wells, gas collection headers, vacuum
 blowers or compressors. Their ultimate purpose is to
 direct the gas to a treatment or utilization system.


 Active Interior Gas Collection/FJecovery Systems
 Active interior gas collection and recovery  systems
 are designed to supplement capping and to prevent
                                                  22

-------
  Figure 10a.   Passive gas control using a permeable trench (U.S. EPA, 1985).
                                                 Section A-A
                                  4" PVC, Vent Pipe'
                                 (Space @ 50' ±  O.C.)
                            4" PVC Perforated Collector
                                   (Continuous)
                                   Drainage
                                   Swale
                                                                              Monitoring
                                                                               Probe
                                                                     Gravel
                                                                    or Stone
                                                                   (i" Min. Size)
Low Groundwater Table, Bedrock
                  Source:  SCS, 1980
                                       "For applications where
                                        venting of gases to
                                         atmosphere is acceptable.

                                       "Collector can be used to
                                         convey gases to a
                                         treatment system.
  Figure 10b.  Passive gas control synthetic membrane
             (U.S. EPA, 1985).
                                          Section A-A
                                     Groundwater
                                  ' Table, Bedrock, etc.
                         tsi
                                                                            Monitoring
                                                                              Probe
                                                             Synthetic
                                                             Membrane
                                                             Natural
                                                             Ground
                                                             Trench
                                                             Backfill
                                                                       Area to be
                                                                       Protected
                                                        Any Convenient Width
                Source: SCS, 1980

lateral gas migration. Gas extraction wells are a
principal component of such systems. Active interior
systems  are quite similar to perimeter gas control
systems and differ primarily in terms of scale (Figure
11). Active interior systems represent the  most
effective means of containing and controlling gaseous
wastes and  can be designed using conventional
equipment  with  little  time  required  for
implementation.  The reliability of such systems  is
limited by their dependence on mechanical  and
electrical components.
                         Corrective Action Application

                         At the Taylor Road landfill (originally intended for
                         the disposal of municipal refuse only), unknown
                         quantities of hazardous wastes from industrial and
                         residential sources were deposited. During the period
                         when the landfill was active, soil and groundwater
                         samples  collected at the site were found to contain
                         concentrations of volatile organic  compounds and
                         metals above acceptable  safe drinking water
                         standards. Analysis of samples collected from private
                         drinking water wells indicated that contamination
                                                   23

-------
Figure 11.   Gas collection/recovery system (U.S. EPA, 1985).
             Refuse Fill
was also present down-gradient from the Taylor Road
site. After the Taylor Road site was closed, methane
gas was detected off-site near adjacent residences.

To handle the methane gas generated from the 42.5-
acre site, an active interior gas collection system was
installed as shown in Figure 11. The installation
consisted of 42 recovery wells, a gas collection header
system, condensate traps, blower station and a fjare
station. In addition, a methane monitoring system
consisting of thirty-two 2-inch wells was  installed
around the site (U.S. EPA, 1987).
Methods to Control Releases from
Surface Impoundments
Surface impoundments are a significant source of
gaseous emissions which can be controlled through a
wide range of strategies. These approaches include
enclosure,  covering the surface with floating solid
objects, the addition  of surface coatings, shape
modification and aerodynamic  modification.
Documentation of specific application of these
technologies is limited.


Enclosures
An enclosure is usually an air-supported structure
which permits the collection and treatment of
gaseous wastes produced by surface impoundments.
Enclosures are susceptible to wind damage and can
be harmed by the wastes they cover. Subject to these
limitations, control effectiveness approaches  100
percent (University of Arkansas? and Louisiana State
University, 1985).


Floating Objects
A variety  of containment strategies employ floating
solid objects to control the rate of gaseous emissions
from surface impoundments. These include: synthetic
membrane covers,  rafts, and hollow plastic spheres.
Synthetic  membrane covers are feasible where the
out-gassing of volatiles due to biological activity is
not expected. Selection of the liner material must be
                                                24

-------
 based on permeability and resistance to the gases to
 be contained. Membrane covers are subject to damage
 by weathering or by contact with wastes. They are
 similar to enclosures in effectiveness, i.e., greater
 than 90 percent  (University of Arkansas and
 Louisiana State University, 1985).
 Rafts are designed  to restrict the surface area
 exposed to air so as to reduce oxygen absorption. They
 are subject to damage by direct waste contact and can
 achieve efficiencies of up to 90 percent.
 Floating hollow spheres are made of polypropylene
 with projections to prevent rotation. They restrict
 oxygen absorption and reduce emissions  with an
 effectiveness of 80 to 90 percent. High winds can pose
 serious problems by blowing  the  spheres away
 (University of Arkansas and Louisiana  State
 University, 1985).
Surface Coatings
Floating oil layers and surfactants constitute a liquid
alternative to floating solid objects. An immiscible
liquid floating on the surface has been found to be
effective in reducing air emissions by up to 90
percent. However, windy conditions can result in a 50
to 80 percent loss of efficiency (University of
Arkansas and Louisiana State University, 1985).
Shape Modification
Shape modification strategies involve lagoon design
and construction to reduce the  ultimate rate of
volatile emissions. Adjusting berm height achieves
this  effect by reducing wind-caused emissions.
Increasing the ratio of depth-to-surface  area also
produces reduced emissions. Orienting the lagoon
with its long axis perpendicular to prevailing winds
helps reduce emissions by maximizing the surface
area which benefits from proximity to  shoreline
protection.
 Aerodynamic Modification

 Aerodynamic modification through the use of wind
 fences represents another strategy for reducing
 emissions under wind-enhanced conditions. Porous
 wind fence material (such as that used for dust
 control) is superior to solid fences. This material can
 achieve emission and oxygen absorption reductions of
 up to 80 percent. The wind fence can be aligned to
 protect from several wind directions and can be used
 to complement the effects of lagoon orientation and
 floating covers. Reduction of wind velocity can be
 expected for a distance of 1  to  5 fence heights
 downwind  of the installation. Fences  should be
 composed  of polyester  or other high-strength
 materials to ensure their  resistance to wind damage
 (University of Arkansas and Louisiana  State
 University, 1985).

 References

 McAneny,  C..and  A.  Hatheway.  Design and
 Construction of Covers for Uncontrolled Landfill
 Sites. In: Management of Uncontrolled Hazardous
 Waste Sites Proceedings, Washington, B.C., 1985
 p.331.

 Spooner, P.A., et al. Slurry Trench Construction for
 Pollution Migration Control,  EPA/540/2-84/001,
 1984a.

 U.S. EPA. Case Studies Addendum: 1-8 Remedial
 Response at Hazardous Waste Sites.  Office of
 Research and Development, Cincinnati, Ohio, 1987.

 U.S. EPA.  Handbook-Remedial Action at Waste
 Disposal Sites (Revised). EPA/625/6-85/006. Office of
 Emergency and Remedial Response, Washington,
 D.C., 1985.

 U.S. EPA. Leachate Plume Management. EPA/540/2-
 85/004. Office of Solid  Waste  and Emergency
 Response,  Office of Emergency and Remedial
 Response, Washington, D.C., 1985.

 U.S. EPA. Underground  Storage  Tank Corrective
Action Technologies, EPA/625/6-87/015, January,
 1987.

 University of Arkansas and Louisiana State
 University.  In-Situ  Methods  for the Control of
Emissions  from Surface Impoundments  and
 Landfills. Draft  Final Report. Prepared for U.S.
Environmental Protection Agency.  Contract No.
CR810856. June 1985. pp. 95.
                                               25

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                                          Chapter 4
        Engineering Considerations for the Corrective Measures Study
The Corrective Measures Study (CMS) elements as
outlined in the EPA document entitled RCRA
Corrective Action Plan - Interim Final (U.S.EPA,
1988) provides guidance to the regulatory community
on the steps practiced by  the engineering community
in the conduct of a feasibility study.  These steps
include:
•   Identification and development of Corrective
    Measure Alternatives
•   Evaluation of Alternatives

•   Selection of  a Corrective
    Implementation.
Measure(s)  for
This logical process ensures that all appropriate
technologies are identified and evaluated on an equal
basis.
Screening of Corrective Measures Technologies
The first step in the screening process is to review the
results of the RFI and reassess  the preliminary
corrective measure technologies identified therein
along with any  supplemental technologies which
have come to  light. By compiling a listing of all
possible treatment alternatives suitable for the site,
an engineer can  then eliminate (1) those that may
prove infeasible to implement, (2) those that rely on
technologies unlikely  to perform satisfactorily or
reliably, or (3)  those that do  not achieve the
corrective measure objective within a  reasonable
time period. From an  engineering standpoint, the
screening process focuses on eliminating  those
technologies which have severe limitations for a
given set of wastes and site-specific conditions. The
screening step may also eliminate technologies based
on inherent technology limitations. Site, waste and
technology characteristics which are used to screen
inapplicable technologies  are described in more
detail below.
Identification and Development of
Corrective Measures Alternative(s)
In order to begin the process of identification and
development of Corrective Measure Alternatives, it is
necessary first to define the problem in terms of the
site conditions determined as a result of the RCRA
Facility Investigation  (RFI). Then, site-specific
objectives  for the corrective  action need to be
established to serve as a basis for technology
assessment and to establish the end point for cleanup
activities. These objectives are generally based on
public health and environmental criteria,
information gathered during the RFI, EPA guidance,
and the requirements of any applicable Federal or
state statutes. For example, all  corrective actions
concerning groundwater releases from regulated
units must  be consistent with, and as stringent as,
those  required under 40CFR264.100.  With
information on current site conditions and  with
cleanup objectives defined, it becomes possible to
develop corrective measure alternatives by screening
the possible technologies and combinations of
technologies identified early in the RFI.
                   Site Characteristics

                   Site data should be reviewed to identify conditions
                   that may limit or  promote  the use of certain
                   technologies. Technologies whose use is  clearly
                   precluded  by site  characteristics should be
                   eliminated from further consideration.


                   Waste Characteristics

                   Identification of waste characteristics that limit the
                   effectiveness or feasibility of technologies is an
                   important part of the screening process. Technologies
                   clearly limited by these waste characteristics should
                   be  eliminated  from  consideration.  Waste
                   characteristics particularly affect  the feasibility of
                   on-site methods, direct treatment methods, and land
                   disposal (on/off-site).


                   Technology Limitations

                   During the screening process, the level of technology
                   development; performance record; and  inherent
                   construction, operation, and maintenance problems
                                               27

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should be identified for each technology considered.
Technologies that are unreliable, perform poorly, or
are not fully demonstrated may be eliminated in the
screening process.  By contrast, certain treatment
methods have been developed to a point where they
can be implemented in the  field without extensive
technology transfer or development.

Through  a  stepwise approach to the screening pf
alternatives, the engineer can gain confidence that
technologies which may be applicable for site cleanup
are not overlooked. In addition, the rationale for the
elimination of specific technologies is available to
justify these engineering decisions to management,
or the regulatory community, and the public.


Identification of the Corrective Measure
AJternative(s)
Based on the screening activities, several
alternatives may be identified which are viable
options for the cleanup of the site. These alternatives
can consist of an individual technology or a
combination of technologies which appear to be
appropriate for the given site conditions and appear
to be capable of meeting the cleanup objectives.

Evaluation of the Corrective Measure
Alternative(s)
Once the candidate corrective measure  alternatives
have been  identified, a more detailed evaluation of
each alternative needs to be undertaken. From an
engineering perspective,  the first  step in the
evaluation  process would include the development of
a conceptual  design for each alternative. The
conceptual design would  consist of a process
description, a process  flow  diagram and a  layout
drawing. Preliminary sizing of equipment and utility
and land requirements would be developed. In
addition, chemical requirements and residuals
produced can be estimated. From the conceptual
design, permitability and residuals disposal  issues
can be identified and addressed.
 Evaluation Criteria
 After the conceptual designs for  each candidate
 corrective measure alternative have been developed,
 each can be compared using the following evaluation
 criteria:
 Technical Criteria

 •  Performance of the corrective measure based on
    the effectiveness of the technology to perform its
    intended function and the length of time the level
    of effectiveness can be maintained.

 •  Reliability of the  corrective measure based on
    operating and maintenance requirements and
   the demonstrated reliability. (This criterion is
   concerned with the complexity of a system and its
   impact on operation, maintenance and potential
   for failure.)

•  Implementability of the corrective measure is
   concerned with  the constructability of the
   facilities (i.e., site constraints,  permitability,
   equipment availability, and the time  it takes to
   implement and to  operate  and maintain the
   facility.)

•  Safety issues include threats to the safety of
   workers or nearby communities during the
   implementation or  operation, of the  corrective
   measures (i.e., fire, explosion and exposure to
   hazardous substances).
Environmental Criteria
An Environmental Assessment for each alternative
(focusing on the facility conditions and pathways of
contamination  actually addressed  by each
alternative) should be prepared. Issues to be reviewed
include: the short- and long-term beneficial  and
adverse effects of the response alternative;  any
adverse effects on environmentally sensitive areas;
and an analysis of measures  to mitigate adverse
effects.
Human Health Criteria

Each alternative should be assessed in terms of the
extent to which it mitigates short- and long-term
potential exposure to any residual contamination and
protects human  health, both during  and after
implementation of the corrective measure.


Institutional Criteria

Institutional needs for eaqh alternative must be
developed as part of the technology evaluation.
Specifically, this should address the effects of federal,
state and local environmental and public health
standards,  regulations, guidance, advisories,
ordinance or community relations on the design,
operation and timing of each alternative.


Cost Estimate
An estimate of the cost for each corrective measure
alternative should be  developed, including capital,
operating and  maintenance costs. Capital costs
consist of  direct  (construction) and indirect
(nonconstruction and overhead) costs.

•   Direct capital costs include:

           Construction costs
                                                28

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           Equipment costs

           Land and site-development costs

           Buildings and service costs

•   Indirect capital costs generally include:

           Engineering expenses

           Legal fees and license or permit costs

           Start-up and shake-down costs

           Contingency allowances


Operation and maintenance costs  are post-
construction  costs necessary to ensure continued
effectiveness of a corrective measure. The following
are examples of typical operation and maintenance
costs:

•   Operating labor costs

•   Maintenance materials and labor costs

•   Auxiliary materials and energy
•  Purchased services

•  Disposal and treatment costs

•  Administrative costs

•  Insurance, taxes and licensing costs


Justification and Recommendation of the
Corrective Measure(s)

After each issue outlined in the  evaluation criteria
has been developed for each corrective measure, the
selection of the most appropriate alternative can be
made. Trade-offs among health risks, environmental
effects and other pertinent technical, environmental
and human health factors enter  into this decision-
making process. In the RCRA context, cost is not a
factor in the selection process except when  two or
more corrective measure alternatives are determined
by EPA to  provide similarly adequate levels of
protection of human health and the environment.

References

U. S.  EPA. RCRA Corrective Action Plan • Interim
Final, EPA/530-SW-88-028, Office of Solid Waste and
Emergency Response, Washington, B.C., 1988.
                                               29

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                                          Chapter 5
     Technology Options for the Treatment of Wastes and Waste Streams
 In nearly every phase  of the Corrective Action
 process,  some information about treatment
 technologies is needed - e.g., in the pre-investigation
 planning for data gathering, in the screening and
 evaluation of candidate remediations, in lab and pilot
 studies, and in design, implementation, operation
 and monitoring of the selected remedy. Many
 documents exist  which  describe candidate
 technologies in detail and give their respective
 applicability and limitations. One intent of the
 seminar on which the present document is based is to
 present a broader perspective on several types  of
 remedial technologies, their applicability and limits
 from a CA perspective and an  understanding of how
 process residuals may themselves require additional
 treatment to achieve protection of human health and
 the environment (HHE).
 equipment, the process controls, and the ancillaries
 necessary to make the reaction proceed in a full-scale
 facility. Figure 13 represents a flow diagram of a
 generic chemical treatment process showing the
 inputs and outputs which require consideration.
 Before the  selection  of  a specific  treatment
 technology can be made, an understanding of the site-
 specific factors which drive the selection of that
 technology is required  because these  factors can
 influence the evaluation of the advantages and
 limitations of competing technologies.  The
 information required to resolve these site-specific
 issues falls into four categories: waste composition
 and matrices, waste quantity, treatment objectives,
 and the reactions involved in the treatment of the
 contaminated material.
 Chemical Treatment Processes for
 Corrective Action

 What Is Chemical Treatment?
 Chemical treatment is a class of processes in which
 specific chemicals are added to wastes or to
 contaminated  media in  order to  achieve
 detoxification.  Depending on the nature of the
 contaminants, the chemical processes required will
 include pH adjustment, lysis, oxidation, reduction or
 a combination of these. Thus, chemical treatment is
 used to effect a chemical transformation of the waste
 to an innocuous or less toxic form. In  addition,
 chemical treatment is  often used to prepare for or
 facilitate the  treatment of wastes  by other
 technologies. Figure 12 identifies specific treatment
 processes which perform these functions.
To understand chemical treatment processes, it must
be remembered that a reaction is not a process. A
reaction involves the chemical transformation of a
material, whether this is carried out on a lab-scale or
an industrial-scale. A process, on the other hand, is a
series of actions or operations needed to make such a
reaction occur in a controlled manner. Thus,  the
development of a process requires the design of the
Applicability Based On Waste Type

In  general, chemical treatment processes are
applicable to a broad range of organic and inorganic
wastes. For example, they can be used for the
oxidation  of organics, for pH  adjustment  to
precipitate heavy metals, and for lysis of chlorinated
organics to cleave  chlorine atoms from organic
molecules in preparation for subsequent oxidative
processes. It should be remembered that chemical
processes are very specific as to the waste that they
treat. Thus, it is frequently necessary to link several
unit operations together to effect the desired removal
objectives. Other waste components must also be
carefully considered because they can affect the
chemical process by  consuming  more  reagents,
generating unwanted precipitates, inhibiting the
reaction or creating safety issues when their presence
is not  recognized (e.g.,  the  production of
intermediates such as CN-, S-2).
Applicability Based On Waste Form
Chemical treatment processes rely on the intimate
mixing of reagents with the waste. Thus, the wastes
generally treated by chemical means must be in an
aqueous or slurry form.
                                              31

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Figure 12.   Chemical processes.
                                        Chemical processes
                  Neutralization
                  Chemical
                  Precipitation
                  PPt
— Hydrogen Perox.

— Ozone


— Air




- KMnO4

— CI2
                                                     — Ferrous Sulfate


                                                     — Ferrous Chloride

                                                     — Sulfur Dioxide

                                                     — Sodium
                                                        Metabisulfite

                                                     •— Alkali Metal
                                                        Dechlorination
                       — Hydrolysis


                       — Photolysis


                         Catalysis
Figure 13.
           Flow diagram of a generic chemical treatment,
           process.
              Treatment
              Chemicals
                         Energy
Contaminated ^
Material
Contan
Generic
Treatment
Process
—
I \
linants By-products
                                      Treated
                                      Material
Treatment Options and Their Applications

pH Adjustment
The function of pH adjustment is to neutralize acids
and  bases  and  to promote  the- formation  of
precipitates (especially of heavy metal precipitates)
which can subsequently be removed by conventional
settling techniques. These purposes are not mutually
exclusive, precipitates can be formed as the result of
neutralizing a waste. Conversely, neutralization of
the waste stream can result when adjusting the pH to
effect chemical precipitation.  Typically,  pH
adjustment is  effective in  treating inorganic or
corrosive wastes.  Figure  14 is a general flow
schematic which illustrates the pH adjustment
process.
                                                   pH Adjustment for Neutralization
                                                   Technology Description: Neutralization is a process
                                                   used to treat acids or alkalis (bases) in order to reduce
                                                   their reactivity or corrosiveness. Neutralization can
                                                   be an inexpensive treatment if waste  alkali can. be
                                                   used to treat waste  acid  and vice versa.  Typical
                                                   neutralizing reagents include:


                                                       Acid: H2SO4, HC1 and HN03
                                                       Base: Ca(OH)2, CaO, NaOH, NaHCO3,
                                                            Na2CO3andMg(OH)2

                                                   Applicability: Neutralization would be appropriate
                                                   for acidic and basic wastes. The process should be
                                                   performed in a well-mixed system. Care should be
                                                   taken to ensure compatibility of the waste  and
                                                   treatment chemicals to prevent the formation of more
                                                   toxic compounds.

                                                   Residuals Produced: The resulting effluent may
                                                   contain dissolved inorganic salts at concentrations
                                                   which may be unacceptable for discharge. Based on
                                                   the  chemical composition of the waste stream, a
                                                   precipitate  may be formed  which may  require
                                                   removal and disposal.
                                                 32

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  Figure 14.    pH adjustment system.
                      Wastewater Treatment System
                        Metal Finishing Industries
                                           Metal Sludge
                                           (30 - 50%)
 Corrective Action Application: An acidic ground water
 at a Florida site (pH 2.5-3) required treatment. The
 groundwater was  collected by extraction wells,
 pumped to an above-ground reactor, and neutralized
 with lime. In the course of neutralizing the  waste
 stream, precipitates were formed  which were
 removed  by clarification and  filtration prior to
 discharge. Sludges  produced from the clarification
 and filtration steps were dewatered by a filter press.


 pH Adjustment to Effect Chemical Precipitation
 Technology Description: To  achieve precipitation,
 acid or base is added to a solution to adjust the pH to a
 point where the constituents to be removed have
 their lowest  solubility.  Chemical precipitation
 facilitates the removal of dissolved metals from
 aqueous wastes. Metals may be precipitated from
 solutions as hydroxides, sulfides, carbonates, or other
 soluble salts. A comparison of precipitation reagents
 is presented in Table 7. Solid separation is effected by
 standard flocculation/ coagulation techniques.


 Table 7.  Comparison of Precipitation Reagents
 Lime
least expensive, generates highest sludge volume
 Caustic and  more expensive than lime, generates smaller
 Carbonates  amount of sludge, applicable for metals where their
           minimum solubility within a pH range is not sufficient
           to meet clean-up criteria
 Sulfides
           effective treatment for solutions with lower metal
           concentrations
 Sodium     expensive reagent, produces small sludge volumes
 borohydride  which can be reclaimed
Applicability/Limitation: This technology is
applicable for aqueous wastes  containing heavy
 metals (i.e., Cd, Cr (III), Pb, Ni). The optimum pH for
 minimum solubility of various metals is not the
 same, therefore, solutions containing mixed metals
 introduce a limitation to  the system.  Figure 15
 graphically shows the solubility of metal hydroxides
 as a function of pH. Chelating or complexing agents
 present  in  the waste stream may inhibit the
 formation of a desired precipitate.

 Residuals Produced: Resulting metal sludges from
 the  chemical precipitation process may require
 further treatment prior to disposal. The effluent pH
 may require an adjustment before  it may be
 discharged.  Dissolved inorganics present in. the
 effluent may pose a problem for direct discharge.

 Corrective Action Application:  Gulf Coast Lead is a
 small, secondary lead smelting facility in Florida,
 which  recovers lead  from discarded  lead acid
 batteries and lead from other battery breakers.
 Contaminated ririsewater and  battery casings were
 dumped into an unlined surface depression causing
 the  soil and the shallow groundwater to become
 heavily contaminated with sulfuric acid and heavy
 metals. A groundwater  treatment  and recovery
 system was installed  consisting of primary
 clarification followed by pH adjustment  (using lime
 or caustic soda) and final clarification. The system
 reduced lead concentrations from 6 ppm to below 0.3
 ppm and adjusted the pH from 1.5 to 9.7. The cleanup
 objectives required that the effluent be below 0.3 ppm
 lead and the discharge volume from  the treatment
 system be 20,000 gpd.


 Oxidation and Reduction Processes

 Oxidation and reduction must both take place in any
 such reaction.  In any oxidation  reaction,  the
oxidation state  of one compound is raised  (i.e.,
oxidized) while the oxidation state of another
                                                 33

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Figure 15.   Solubilities of metal hydroxides as a function of
          pH.                                 i
     100
                    8     9
                     Solution pH
 compound is lowered (i.e., reduced). Oxidation and
 reduction reactions are  utilized to change the
 chemical form of a hazardous material in order to
 render it less toxic or to change its solubility,
 stability, separability  or otherwise change it for
 handling or disposal purposes. In the reaction, the
 compound supplying the oxygen (or chlorine or other
 negative ion) is called the oxidizer or oxidizing agent
 while the compound accepting the oxygen (He.,
 supplying the  positive  ion) is called the reducing
 agent. The reaction can be enhanced by  catalysis,
 electrolysis or photolysis.


 Chemical Oxidation
 Technology Description: Oxidation processes involve
 the conversion of organics to CO2, H2O, HC1, NO2
 and SOa or the conversion of inorganics to a more
 desirable form. For both  organic and inorganic
 wastes, the function of  chemical oxidation is  to
change the chemical form of the molecular structure
for the purpose of detoxification. Typical oxidants
used for oxidation processes are:
                                                                 Air
                                                                 02
                                                                H202
                                                                 03
                              C12
                              C102
                             KMnO4
                             NaS2O7
                                                   Oxidation processes may rely on pH adjustment to
                                                   enhance the chemical reaction. Figure 16 illustrates
                                                   the typical configuration of a chemical  oxidation
                                                   process. The major engineering considerations for
                                                   chemical oxidation include: reaction kinetics, mass
                                                   transfer, by-products,  temperature,  oxidant
                                                   concentration, pH and vent gas scrubbing.

                                                   Figure 16.    General process flowsheet for chemical
                                                              oxidation.

                                                                          Feed     Vent   Gas
                                                                             J	L
                                                                                            Acid or
                                                                                            Base
                                                      Catalyst
                                                      Recovery
                                                      If Required
                                                                            Effluent
 Applicability/Limitations: The process is nonspecific.
 Solids must be in solution. Reactions can be
 explosive. Waste composition must be well known to
 prevent the inadvertent production of a more toxic or
 more hazardous end product. Oxidation processes are
 applicable for the following classes of organic
 contaminants:

 •   High reactivity  contaminants: phenols,
     aldehydes, aromatics, amines,  some sulfur
     compounds.
 •   Medium reactivity contaminants: alcohols,
     ketones, organic acids, esters, alkyl-substituted
     aromatics, nitro-substifcuted aromatics,
     carbohydrates.
 •   Low  reactivity contaminants:  halogenated
     hydrocarbons, saturated aliphatics, benzene.
 •   Cyanide-bearing wastes.
                                                 34

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 The reaction mechanism depends on the chemistry of
 the active oxidant and chemical contaminants.
 Multiple sequential and parallel reaction steps occur
 frequently. Partial oxidation produces noxious by-
 products.

 Residuals Produced: Typical residuals resulting from
 oxidation are partial oxidation  products  (e.g.,
 chlorinated organics) and inorganic salts (e.g., NaCl,
 Mn02).  Additional treatment  may be required to
 permit disposal.

-Corrective Action Application: At a hazardous waste
 treatment  storage  and disposal facility in
 Washington State, a cyanide-bearing waste required
 treatment. The influent waste  stream contained 15
 percent  cyanide. Electrolytic oxidation was used to
 reduce  the cyanide concentration to less than 5
 percent. Alkaline chlorination  was used to further
 reduce the cyanide concentration to 50 mg/1 (the
 cleanup objective). The electrolytic process was used
 as a first stage treatment because the  heat of
 reaction, using alkaline chlorination to treat  the
 concentrated cyanide waste, would be so great that it
 would melt the reactor tank.


 Chemical Reduction

 Technology Description:  The function of reduction
 processes is to convert inorganics to a  less  toxic
 and/or more easily treated form. It also serves as a
 pretreatment step for  inorganics in which chemical
 precipitation is used to remove the metal hydroxide
 from solution.

 Applicability/Limitations: Reduction  processes  are
 applicable for:
    Hexavalent chromium waste
    Mercury wastes
    Hexavalent selenium
    Organic lead compounds
    Chelated-metal-bearing wastes
Chemical reduction process limitations include the
following:

•  Reducing agents are non-selective.
•  Violent reactions are possible.
•  Air emissions and odors can.be produced.
•  Slurries, tars or sludges are difficult to treat.

Residuals Produced: The  reaction products are
usually inorganic salts.

Corrective Action Application: At a RCRA site in the
southwest, a waste stream containing hexavalent
chromium was reduced to the trivalent form. The
trivalent chromium  was then removed using ion
exchange. The influent hexavalent chromium
concentration was less than 50 ppm, and the effluent
concentration was 0.5 mg/1 (the cleanup objective).
Alkali Metal Dechlorination

Technology Description:  Chlorinated organics
represent a  large class of toxic and hazardous
substances that are difficult to treat. The purpose of
this process  is to displace the chlorine from the
chlorinated compound. By-products include chloride
salts, which can be removed by centrifugation and
filtration. The reagents used are metallic sodium and
potassium in conjunction with proprietary  reagents.
For the sodium based processes,  the  reagents are
suitable for treating oils containing less than 1000
ppm PCBs.

Applicability/Limitations:    Alkali    metal
dechlorination  is applicable  to  chlorinated
hydrocarbons such as:

•   PCBs (e.g., transformer decontamination)
•   Dioxins
•   Solvents
•   Pesticides

Alkali metal dechlorination processes are water
sensitive. Soil moisture content can adversely affect
the reaction in  in-situ soil applications. The
application  of alkali metal  dechlorination is
generally expensive.

Residuals Produced: The residual produced from the
alkali metal dechlorination  of soils is reported to be
an alkaline soil which requires neutralization.

Corrective Action  Application: At a Navy facility in
Guam, approximately 25 tons of PCB  contaminated
soil  was treated using the KPEG (potassium
polyethylene glycol) process. PCB concentrations
were  reduced from 3000 ppm to less  than 5 ppm.
Upon completion of treatment using  the  KPEG
process, the soil was neutralized from a pH of 14 to 7.
A full-scale system for this process is currently under
development.
Lysis Processes
The  basic function of lysis processes  is to split
molecules to permit further treatment. Hydrolysis is
a chemical reaction in which water reacts with
another substance. In the reaction,  the  water
molecule is ionized while the other compound is split
into  ionic groups. Photolysis, another lysis process,
breaks chemical bonds by irradiating a chemical with
ultraviolet light. Catalysis uses a catalyst to achieve
bond cleavage.
                                                35

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Hydrolysis

Technology Description: Hydrolysis is the process of
breaking a bond in a molecule (which is ordinarily
not water-soluble) so that it will go into ionic solution
with water. Hydrolysis can be  achieved by  the
addition of chemicals  (e.g.,  acid hydrolysis), by
irradiation (e.g., photolysis) or by biological action
(e.g., enzymatic bond cleavage). The cloven molecule
can then be further treated by other means to reduce
toxicity.

Applicability/Limitations: Hydrolysis is suitable for
pretreating difficult-to-treat wastes and for organics
with substituents, such as phenols or chlorinated
organics with reactive chlorine atoms. Hydrolysis is
specific for only a limited number of contaminants.

Residuals Produced: The resulting residuals from a
hydrolysis process are an aqueous effluent and
insoluble organics.                             ;

Corrective Action Application:  Hydrolysis was
favorably applied to a site in which the wastewater
contained very soluble, refractory organics. In
addition, tars were being produced in high quantities
on this site. Both of these problems were solved using
a hydrolyzer. Figure 17 illustrates a flow diagram of
this process. As a result, the wastewater treatment
goals were achieved, and the production of tar  was
reduced.
            Hydrolysis of refractory organics.
                               Water, acid or base
         Energy
                                    By-products
 Ultraviolet Photolysis
 Technology Description: Ultraviolet (UV) photolysis
 is a process  that destroys or detoxifies hazardous
 chemicals in aqueous  solutions utilizing UV
 irradiation. Absorption of UV energy results in a
 molecule's  cleavage, increasing the  ease of
 subsequent oxidation of the molecule. For example,
 ultraviolet light has  been used for degradation of
 dioxins in waste sludge. This process required
 extraction (into a clean, transparent solvent) of the
 waste  to  be destroyed.  Reaction  products were
dechlorinated materials and free chlorine gas. In
addition, the use of UV photolysis on nitrated wastes
has been successfully demonstrated on a pilot scale.

Applicability/Limitations: Photolysis is appropriate
for difficult-to-treat  chemicals  (e.g.,  pesticides,
dioxins, chlorinated organics), nitrated wastes, and
those chemicals in media which permits photolyzing
the waste. The  waste matrix can  often  shield
chemicals from the light  (e.g.,  ultraviolet light
absorbers, suspended solids,  solid  wastes). The
photolysis process typically requires pretreatment to
remove suspended materials, and the by-products
formed may be more toxic than the parent molecules.

Residuals  Produced:  Photolysis  produces
decomposition products of dechlorinated material
and free chlorine gas.

Corrective Action Application: At a manufacturing
site, photolysis was used to cleave chlorine atoms
from tetrachlorodibenzodioxin (TCDD). The basic
flow diagram for  the process is shown in Figure 18.
The  wastes from a hexachlorophene process  were
stored in an underground tank  which held  4300
gallons of the oily residuals containing 343 ppm
TCDD.  This material required  removal  and
treatment. The selected treatment system consisted
of a batch solvent extractor to transfer the TCDD into
a cleaner fluid more  amenable to photolysis. The
solvent was separated from the oil, circulated
through a bank of eight 10-kW ultraviolet lights,
recovered and recycled. Effluent  from this process
contained 0.15 ppm TCDD.

  Figure 18.   Photolysis flow diagram.

                       UV Light
                                                                           Effluent
 In-Situ Chemical Treatment
 Technology Description: In-situ chemical treatment
 uses the same principles employed for above-ground
 chemical processes.  Materials  are added  to
 neutralize, oxidize  or  remove contaminants  in
 groundwater or soils in order to avoid digging or
 pumping of the contaminated waste above ground for
                                                 36

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 treatment. The reagents which have been used for in-
 situ chemical treatment include:
  Figure 19.   Site of formaldehyde release.
    Dilute acids or bases
    Hydrogen peroxide
    Water
    Water with additives
    Air
 Applicability/Limitations: In-situ treatment can be
 used when it is uneconomical to haul or  when
 infeasible or uneconomical to dig or pump  the
 contaminated 'waste matrix for  treatment in a
 reactor. This approach should be used whenever
 excavation or removal causes an increased threat to
 human health. It can reduce the cost of a remediation
 program. Because  chemicals are applied to  the
 contaminated waste matrix, specifically soil and
 groundwater, a potential exists for reaction with the
 soil. Permeability problems can occur as the result of
 precipitate formation. This can result in inadequate
 mixing of the contaminant with the treatment
 chemical. Gas generation may also occur.

 Corrective Action Application: A case involving  the
 cleanup of a 20,000 gallon formaldehyde release
 utilized in-situ treatment due to the- location of the
 spill. The release occurred from a break in an
 underground pipeline at a tank farm (Figure 19). The
 soil could not be excavated because it served as a road
 for trucks. The  objectives were to remediate  the
 release; reduce the long-term liability for oxidizing
 the formaldehyde; and reduce the time and cost for
 groundwater treatment without interfering with
 operations in the area. The process (Figure  20)
 involved slowly injecting alkaline hydrogen peroxide
 into the clay till to oxidize the formaldehyde without
 creating excessive temperature and pressure
 increases. The results were that the formaldehyde
 was reduced from percent concentrations to 1-18 ppm.
 The permeability of the soil improved, arid the overall
 treatment costs were significantly less than removal
 followed by above-ground treatment.
Biological Processes for Corrective
Action

What is Biological Treatment?
Biological treatment is a destruction process relying
primarily on oxidative or reductive mechanisms.
Enzymatic activity can effect lysis (e.g., hydrolysis or
dehalogenation). Further, biological activity  can
result in pH changes in the waste stream which may
require  adjustment by chemical means. The use of
biological treatment processes  is directed toward
accomplishing (1)  destruction  of  organic
contaminants, (2) oxidation of organic chemicals
whereby the organic chemicals are broken down into
smaller constituents, and (3) dehalogenation of
                                                     Failed Formaldehyde Pipeline
organic chemicals by cleaving a chlorine atom(s) or
other halogens from a compound. Specific engineered
systems to effect oxidation and reduction for different
matrices  are presented  in Figure 21. Biological
treatment processes have certain advantages over
other common treatment technologies, namely,  the
organic contaminants to be destroyed are used and
transformed by bacteria or other organisms as a
source of  food. These processes can be employed in
soils, slurries, or waters (ponds, groundwater, etc.) to
aid in the remediation of a site.


Applicability Based on Waste Type

Biological processes can be used on a broad class of
biodegradable organic  contaminants. Table 8
presents some  common RCRA-regulated organic
compounds which are susceptible to biodegradation.
Some compounds, called refractiles, are persistent
compounds which are not readily  biodegradable. It
should be noted that very high concentrations as well
as very low concentrations of organic contaminants
are difficult for biological processes to treat.


Applicability Based on Waste Form
Biological treatment processes can be used to treat
organic contaminants in liquid,  slurry, and soil
matrices.  However, it should be remembered that
moisture is an essential need of the biomass both for
                                               37

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Figure 20.   Diagram of In-sltu treatment.
                      H202
                              Tracer
           Water
 Figure 21.   Biological processes.
  Biological Processes
1                 Oxidation of Organics
                        I
  Biological Processes
                 Aerobic Processes
          — Soils
             L
                in-situ
             Liquids

              I— in a
                 reacto'r
                         I    Liquids - in
        a reactor
— Suspended growth

— Fixed film

  ' Hybrid
    Liquids
                                     In-situ
                               Lin ar

                               in-si1
  in a reactor

  in-situ
growth and to provide mobility either of the food to
the biomass or the biomass to the  organic. Thus,
matrices which do not have sufficient moisture will
not support biodegradatioh, and methods to add
moisture may have to be engineered into the system.


Environmental Factors  Necessary to Maintain the
Biomass
Since microorganisms need appropriate conditions in
which to  function, an  engineer must provide an
optimum environment,  whether above ground in a
reactor or below ground for an in-situ application.
The primary environmental factors which can affect
the growth of the microbial community - in addition
to providing them with sufficient food (organic
material) -  are  pH,  temperature, oxygen
concentration, nutrients, and toxicity.
pH
Typically, the biological treatment system operates
best when a waste stream is at a pH near 7. However,
waste treatment systems can operate (with some
exceptions) between pH values of 4 and 10. The
                                                  38

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 exceptions are aerobic systems in which ammonia is
 oxidized to  NOX as well as anaerobic methane
 fermentation systems. For these, the pH should be
 between 6 and 8. At the extremes of this range, the
 system will function, but efficiency will suffer.
 Temperature
 Waste treatment systems can function over a very
 wide temperature range, e.g., 5° to 60°C. However,
 there are three  rather distinct  ranges in which
 different groups of organisms function:
        Psychrophilic
        Mesophilic
        Thermophilic
<15°C
15°to45°C
>45°C
 Most  waste treatment systems  operate in  the
 mesophilie region. The expense  of altering  the
 temperature of wastes encountered in abnormally
 cold or warm environments indicates the desirability
 of developing organisms which are suited to extremes
 of ambient waste temperatures.


 Oxygen

 Microorganisms need a certain amount of oxygen not
 only to survive, but also to mediate their reactions.
 Therefore,  the  residual dissolved  oxygen
 concentrations  should  be  maintained  at
 approximately 2 mg/€  or greater within a typical
 liquid biotreatment  system. Having this much
 oxygen "left over" indicates that sufficient oxygen
 was available for the biological process.
Nutrients

Nutrients can be classified into three groups based on
levels required in waste treatment systems. These
are given in Table 9. The major nutrients can be
identified from the generalized biomass formula (Cgo
Hg2 C>23 Ni2 P). The actual quantity needed depends
on the biochemical oxygen demand (BOD) of the
waste. The higher the BOD the greater the quantity
of cells produced. The minor and trace nutrients are
needed in small quantities and are given in terms of
concentration because these are the  levels needed in
solution to force the small amount required inside the
cell across the cell-wall membrane.

For many of the trace nutrients, it will be difficult to
find  literature references to the  concentrations
required. It is only recently that it has been realized
that these trace nutrients are required, because they
were only present as contaminants in  biological
preparations. Indeed,  many other substances may be
required nutrients but at such low levels that their
requirement is not easily manifest.
 Toxicity

 The presence of toxic substances will obviously
 produce adverse conditions in a biological system.
 Unfortunately, it is difficult to cite specific toxic
 materials because toxicity depends on concentration.
 All of the nutrients previously mentioned can be
 toxic if their concentration is excessive. All types of
 organic compounds which can be used as food by
 bacteria can be toxic if the level is high enough. Thus,
 our concept of a toxic substance is a substance which
 is toxic at, a very low concentration. (Little detailed
 information on ranges in which substances are toxic
 is available.) In addition, phenomena such as
 acclimation, antagonism and synergism will alter
 toxicity effects. Frequently, toxicity concerns can be
 avoided  by  waste  dilution and  by microbe
 acclimation. Acclimation is most important when
 dealing with "toxic waste". For example, with
 unacclimated  biomass, a few milligrams per liter of
 phenol can produce toxicity; but after acclimation,
 waste treatment systems can easily handle  wastes
 containing up  to 500 mg/t of phenol.


 Biological Processes and Their Applications

 Engineered Processes to Achieve Oxidation

 Aerobic processes are oxidative processes and are the
 most widely used biological treatment processes for
 organic wastes. These processes rely on providing the
 basic environmental conditions required for
 biological growth but use differing methods for
 maintaining the microorganisms in the system and
 contacting the organic material with  the biomass.
 Since these systems require a supply of molecular
 oxygen, the cost of supplying oxygen frequently sets
 an economic limit on the concentration of organics
 which can be present in the wastewater. For
 conventional  systems, a limit of approximately
 10,000 mg/€ BOD is  a good rule of thumb. For
 situations where  the flow is low, however, higher
 concentrations can be economically biodegraded.
 Engineered aerobic processes include  suspended
 growth systems, fixed-film systems, hybrid reactors
 and in-situ application.


 Suspended Growth Systems

 Technology Description: Suspended growth systems
 maintain  the  biomass suspended  in the aqueous
 waste to be treated. Intimate mixing brings the food
 and the microorganisms into contact  and permits
 biodegradation to occur. The biomass is captured as it
 is  washed  out of the reactor. Typically, a clarifier is
 used to capture washout. The biomass is concentrated
 as sludge and a portion is recycled back to the reactor
 to  maintain the concentration  of biomass  in the
 reactor while the remainder is dewatered  and
disposed. This  system allows a long contact time
between the organic waste and the biomass. Figure
                                               39

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Table 8. Biodegradable RCRA-Regulated Organic Compounds, (USEPA, 1985)
                                              Respiration
           Substrate Compounds
Aerobic Anaerobic  Fermentation   Oxidation     Co-oxidation
 Straight Chain Alkanes
 Branched Alkanes
 Saturated Alkyl Halides
 Unsaturated Alkyl Halides
 Esters, Glycols, Epoxides
 Alcohols
 Aldehydes, Ketones
 Carboxylic Acids
 Amides
 Esters
 Nitrites
 Amines
 Phthalate Esters
 Nitrosatnines
 Thfols
 Cyclic Alkanes
 Unhalogenated Aromatics
 Halogenated Aromatics
 Simple Aromatic Nitro Compoufids
 Aromatic Nitro Compounds with Other
     Functional Groups
 Phenols
 Hatogenated Side Chain Aromatics
 Fused Ring Hydroxy Compounds
  Nitrophenols
  Halophenols
  Phenols - Dihydrides Polyhydrides
  Two & Three Ring Fused Polycyciic
     Hydrocarbons
  Biphenyls
  Chlorinated Biphenyls
  Four Ring Fused Polycyciic Hydrocarbons
  Five Ring Fused Polycyciic Hydrocarbons
  Fused Polycyciic Hydrocarbons
  Organophosphates
  Pesticides and Herbicides
    -h

    •I-
+

+
             +

             +
       Table 9.  Nutrients for Biological Treatment
        Major    (Quantity depends on waste strength)
                 carbon, hydrogen, oxygen, nitrogen, phosphorus
        Minor    l-100mg/£
                 sodium, potassium, ammonium, calcium, magnesium, iron, chloride, sulfur
        Trace    Less than 1 mg/€
                 manganese, cobalt, nickel, vanadium, boron, copper, zinc, various organics (vitamins),
                 molybdenum	
                                                  40

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  22 represents a general illustration of a suspended
  growth system.

  Applicability/Limitations: Suspended growth systems
  are applicable to organic wastes with a moderate to
  high organic load. In addition, these systems are less
  susceptible to shock and thus are suitable  where
  fluctuations in influent feed  are anticipated.
  Limitations to the use of suspended growth systems
  are  generally associated with  lower  level
  concentrations of organics in the feed. In these cases,
  the maintenance of the biomass within the system is
  not possible because of the low food to mass ratio. In
  addition, if the growth rate of a viable  biomass
  population is  sufficiently slow, then a more positive
  means for maintaining the biomass in the system is
  required.

 Residuals Produced: The residuals produced from
  suspended growth systems are the excess  biomass
 produced as the  result of biodegradation. In general,
 this  biomass can be disposed  without  further
 treatment.  However, site-specific conditions may
 require stabilization prior to disposal.

 Corrective Action Application: Under  a Gulf  Coast
 hazardous waste site in Robstown, Texas, a portion of
 the brine groundwater had become contaminated
 over  the course of several years. The sources of
 contamination were removed, and the plume was
 confined to  the  site boundary. The cleanup of the
 groundwater was the only remaining (and the most
 difficult) task to perform. The combined influent
 water had an  average concentration of 15,000 mg/£
 dissolved solids and 1300 mg/€ total organic carbon
 (TOG) with  the  main component being 400 mg/€ of
 phenol. For reinjection, the influent had to be treated
 to background quality (< 18  mg/€ TOC).  Since the
 natural groundwater is brine, the  dissolved solids
 were not removed. The optimum pumping rate from
 the wells was  determined to be 23,000 gal/day. At
 this rate of removal and recharge, the  design life of
 the treatment system was projected at 10 years.

 The process selection for the treatment  system
 considered several important  and unique problems
 concerned with the treatment of a brine groundwater.
 The most critical  problem was a  decrease in the
 concentration of  organics in the groundwater with
 time as the treated water was returned to the ground
 and forced back to the central  wells. Before the full-
 scale system was put into service, a large-scale pilot
 plant was run  to  ensure that the assumptions made
 from the laboratory data  were correct. In 1984, the
 full-scale system (as shown in Figure 23) included the
 following components: a first stage activated sludge
 system; a second stage fixed-film biological reactor; a
dual media filter; and a  carbon adsorption column.
 Using these  components of the full-scale  system,
groundwater was pumped out of the ground, treated,
and then recharged back into the ground  (Nyer,
  1987). As the concentration of the effluent decreases,
  the system configuration is modified (Figure 23).


  Fixed-Film Systems

  Technology Description: Fixed-film reactors rely on
  maintaining the biomass on some media and passing
  the contaminated organic material over that media to
  promote biological activity.  In classical municipal
  treatment, trickling filters are an example of a fixed-
  film system. In the industrial and  hazardous waste
  treatment arena, fixed-film reactors make  use of
  rotating biological contactors (RBC) or packed media
  reactors. Oxygen transfer is promoted by (1) in the
  case of the RBC, rotating the discs into and out of the
  waste  stream, and (2) in the case of packed  media
  reactors, passing a thin liquid layer over the media.
  The advantages of these  processes include the
  following:

  •  The biomass is retained in the  reactor on inert
    media.
  •  The design of the bioreactor is  based on the
    specific surface area.
 •  High concentrations or high  mass of viable
    bacteria can be maintained in a relatively small
    volume.
 •  BOD removal is approximately 85 to 90 percent.

 An illustration of a fixed-film  reactor  system is
 presented in Figure 24.

 Applicability/Limitations: Fixed-film reactors are
 applicable to  influents containing  lower
 concentrations of organics  or for  maintaining a
 specialized, slow growing biomass such as would be
 required to degrade complex organic wastes. A
 variation of this concept is a kind of in-situ or on-site
 treatment in which the soil serves as the media and
 nutrients are  passed through the soil to promote
 bacterial growth. Because the flow through  these
 systems is essentially plug flow, fixed-film  reactors
 are adversely impacted by shock  loadings.  In
 addition, high concentrations of organics in  the feed
 can produce excessive amounts of biomass which can
 clog  or (by sheer  weight) destroy the media
 supporting the biomass.

 Residuals Produced: The residuals produced in a
 fixed-film reactor are normally small when compared
 to the residuals produced in a suspended growth
 system.  There can be some sloughing of biomass
 during system operations, and this may need  to be
 separated from the effluent. The residuals, depending
 on site-specific requirements, may require additional
 treatment prior to ultimate disposal.

 Corrective Action Application: At a dry cleaning
facility in a desert area of California, an underground
solvent  storage  tank  was  found to have leaked for
many years. The soil from the 100-ft x 160-ft by 20-ft
                                               41

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Figure 22.   Diagram of the suspended growth system.
                                             Mixer
                 Waste
                                                               Clarified
                                                               Effluent
                               Biomass Recycle
                                                                    Excess Biomass
Figure 23.   Llfe-cycla design - Installed system at southern Texas site (treating phenol in a brine aquifer) (Nyer, 1987).
                                        1300 mg/l TOC
                                         <900 mg/LTOC

                                               H/TOX
   ^-farJLr
                                 Clarifer
                           Aeration "*"""*~j    |
                                            Blowers
           Dual Media   CarbQn
           Filter      Adsorption
                                          <100 mg/lTOC
                                                                -JlT
                                                                    Carbon
                                                                    Adsorption
 deep site was excavated. The pit was lined with
 plastic and covered by gravel for drainage. The soil
 was put back into the lined pit. Nutrient rich water
 was allowed to percolate down through the soil to feed
 the indigenous microbes. The water was recovered
 from a ground drain (O. Russ, EMCON Associates,
 personal communication, 1988).

 Some key issues learned from this case were:
•  Injection of acidic, nutrient-rich water into the
   highly alkaline soils resulted in "cementing" of
   the soils.

•  To alleviate this "cementing", the microbes were
   grown above-ground in a 500-gal container. They
   were then allowed to percolate down through the
   soil. This inoculum had a neutral pH and did not
   react with the soil.
                                             42

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  Figure 24.   Diagram of the film flow reactor.
                                                     Flow Distributor

                                                           Inert Packing
            Waste
                                                Effluent Recycle
 •  At a percolation rate of 500 gal/day, the time for
    cleaning the soil is projected to be 6 months.


 Hybrid Reactors

 Technology Description: Hybrid reactors, as the name
 implies, are a combination of suspended growth and
 fixed-film reactor principles. In these systems, the
 fixed film is submerged and the reactor contents are
 continuously stirred. A large amount of biomass is
 maintained in the system.

 Applicability/Limitations:  Hybrid  reactors,
 depending upon their configuration, can handle high
 organic loads (i.e., in the range of 50 to 10,000 ppm).
 Because these reactors  are a completely mixed
 system, they are less affected by shock loadings.
 Hybrid reactors are designed to compensate for the
 principal limitations  of  fixed-film and suspended
 growth reactors. However, set-up and operation of
 hybrid reactors will  tend to be somewhat more
 technically demanding than either fixed-film or
 suspended growth systems.

 Residuals Produced: As with the suspended growth
 and fixed-film systems, some biomass is produced
 which will require disposal.  The pretreatment and
 disposal practices required will depend on site-
 specific requirements.

 Corrective Action Application: Case 1 - Groundwater
 at the MEMOREX Computer Tape Plant (Santa
 Clara, California) was contaminated by a leaking
 underground solvent storage tank (Skladany et al.,
 1987). Chemical analysis  of the groundwater
 identified the presence of methyl ethyl ketone (MEK)
 up to  500 ppm; xylenes together with ethyl benzene
 up  to 40 ppm; cyclohexanone  up  to  30 ppm;
cyclohexanol up to 10 ppm; acetone up to 10 ppm; and
toluene,  tetrahydrofuran, 2-butanol, and methyl
propyl ketone each less than 1 ppm.  A biological
 system consisting of two submerged fixed-film
 biological reactors in series was designed for
 treatment of the contaminated groundwater, as
 shown  in Figure 25. By operating the reactors in
 series,  the first unit was used to remove the bulk of
 the contaminants present. The second unit acted as a
 biological polishing unit. The design permitted one of
 the bioreactors to be removed or bypassed as the
 groundwater contaminant concentration decreased
 over time. Following the bioreactors, to ensure that
 the effluent met  all applicable discharge criteria,
 were cartridge filters (to remove suspended solids)
 and two carbon units (each containing 600 pounds of
 carbon). The  treatment system was designed to
 handle  a continuous flow of 15 gallons per minute
 (gpm) and to attain effluent MEK concentrations of
 less  than 1 ppm and other  total organics
 concentrations of less than  100 ppb. Initial influent
 analysis indicated that MEK concentration to the
 biotreatment system was in the order of 510 ppm, at a
 flow rate of 8 gpm. Subsequently, additional solvent-
 contaminated wastes  at the site also  required
 treatment; therefore, the groundwater/solvent wastes
 biotreatment system was revised as shown in Figure
 26. The major contaminants treated at the plant
 continued to be MEK and cyclohexanone.

 Case 2 - The Hyde Park Landfill site, located in an
 industrial complex in the extreme northwest corner
 of Niagara, New York, was used from 1953 to 1975 as
 a disposal site for an  estimated 80,000 tons  of
 chemical waste, including chlorinated hydrocarbons.
 A compacted clay cover was installed in 1978 over the
 landfill  and a  tile leachate collection system was
 installed in 1979. Hazardous compounds such as
 ortho-, meta-  and para-chlorobenzoic acid;  toluene;
ortho- and  meta-chlorotoluene; 3,4-dichlorotoluene;
and 2,6-dichlorotoluene were detected in the leachate
 (Irvine et al., 1984). Since 1979, the existing leachate
treatment system has used activated carbon  as the
technology  for removing organic carbon. Although
                                               43

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Flfluro 25.   DETOX H-series submerged fixed-film biological reactor (Skladany et al., 1987).
                                                                                      High' Surface Area
                                                                                      Plastic media
                                                                                             Influent
                                                                                             Water
                                                                                      !    Media
                                                                                          Support
                                                                                     Aeration Piping
                                                                   Air Inlet
      Effluent Outtfi
    Figure 26.    Process diagram for revised groundwater and solvent wastes biological treatment system.
                                            I
Extraction Well
                                         Complete Mixed Bioreactor
                                                 #1
                                                Clarifier
                                         Complete Mixed Bioreactor
                                                 #2
 producing a suitable quality effluent, the treatment
 of Hyde  Park leachate  by conventional  carbon
 technology was unacceptable from an economic
 standpoint. For the purchase of carbon alone,  the cost
 forecast was $21 million over a 10-yr period (Irvine et
 al., 1984).
          Review of several alternative technologies to reduce
          the load of organic carbon on the activated carbon
          system produced the  following conclusions.  The
          organic constituents of the leaehate (which accounts
          for about 60  percent of the combined wastewater
          volume but more than  80 percent of the total organic
                                                    44

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  loading to the existing adsorption system) were found
  to be easily biodegraded. Biological pretreatment of
  the combined wastewater in SBRs was capable of
  reducing  the carbon requirements by 90 percent
  (Yingetal.,1986).

  Subsequently, biological/physical treatment of
  leachate  with  an activated  carbon-enhanced
  sequencing batch bioreactor (PAC-SBR) was
  analyzed  to  determine whether the improved
  treatment by  simultaneous adsorption and
  biodegradation in the SBR would  produce an
  acceptable effluent without post-treatment in the
  existing granular activated carbon adsorber (Ying et
  al.f 1986).                                   *
 In-Situ Biological Treatment

 Because biological activity is frequently occurring in
 the natural environment,  the key  to  in-situ
 bioremediation involves providing those conditions
 which will enhance biodegradation. In-situ biological
 treatment requires the application of fundamental
 nutrients or feed augmentation to promote biological
 growth to a contaminated groundwater or soil.

 Technology Description: In-situ biological treatment
 is site-specific, but in general may require the
 injection of nutrients,  oxygen and  microbial
 populations to degrade the organic material present.
 Usually,  extraction wells are  used to  pump
 groundwater from beneath the  site for use as a
 carrier for the supplemental materials which need to
 be applied (either to the groundwater or the soil) in
 order to  provide the appropriate environment for
 biodegradation.

 Applicability/Limitations: In-situ  treatment is
 applicable to sites where the removal  of the
 contaminated material would be difficult  and in
 which biodegradation is currently taking place to a
 limited degree. This  would include  sites close to
 structures, along active railroad tracks, and where a
 large volume of contaminated  soil or groundwater
 requires  treatment.  The limitations of in-situ
 bioremediation are associated with the ability to
 achieve adequate contact of the  biomass with the
 waste  in the underground environment and to
 determine the degree of degradation achieved by the
 treatment process.

 Corrective Action Application:  Case 1  - A  spill
 occurred at the Houston Chemical Company (located
 in Texas County, Missouri) in June 1979 (U.S. EPA,
 1984). An estimated 15,000 gallons of a 5 percent
 solution of pentachlorophenol (PCP) in diesel oil was
 released  as shown in Figure 27. The emergency
physical cleanup operations performed at the site
were:
     •   Skimming and vacuuming floating PCP/oil
         from the catch basin and pond;
     •   Excavating and removing contaminated soil
         from the PCP/oil spill path and from the farm
         pond bottom;
     •   Constructing  surface water diversions
         around the farm pond; and
     •   Sealing of the well at the plant site.

 The water in the farm pond was treated by carbon
 adsorption  and  returned  to the  pond.  The
 biotreatment  operations  performed  at the pond
 consisted of the inoculation  with nonindigenous
 microbes for  the  purpose of degrading the low
 concentrations of PCP/oil remaining in the water and
 soil. Mechanical aerators were installed to provide
 oxygen.  PCP levels were  reduced using  a
 bioremediation from  a  range  of 250-400 ug/€ to  a
 value of  10  ug/€  (the  clean  up  objective).
 Subsequently, these concentrations rose to 400 ug/€,
 but it was anticipated that continued biodegradation
 at the site would occur. Since this was an emergency
 response action, no follow up monitoring of the site
 was performed.

 Case 2 - At a midwestern industrial  facility, two of
 the  seven 6000-gal storage tanks were leaking fuel
 oil and waste solvents. The underground vault (25 ft
 x 70 ft x 12 ft deep) contained seven 6000-gal tanks ,
 for storing clean fuel oils and waste solvents from the
 laboratory facility. Groundwater contamination was
 confined primarily to the  underground vault, but
 some dissolved hydrocarbons  were detected in the
 clay stratum immediately adjacent to  the tank. Soils
 throughout the vault  were  saturated  with aromatic
 and  aliphatic hydrocarbons. Total contamination was
 calculated to  be  655  gallons  of free products
 (solvents/fuel mixture)  and 300 to 900 gallons of
 adsorbed hydrocarbons (Brenoel and Brown, 1985). A
 two  phase  remediation approach was  chosen. In the
 first phase, free  products  were recovered. In the
 second phase of remediation, biostimulation was
 employed. The basic elements of the installed
 biostimulation process included a  groundwater
 circulation system to  sweep the contaminated area
 (i.e., a system of injection and recovery wells) and.
 nutrient and oxygen injection capabilities. The
 nutrients  were required for  stimulation of  the
 bacteria and controlled degradation of hydrocarbons.
 Two  formulations were used: a blend  of ammonium
 chloride and sodium phosphates and  a formulated
 oxygen-enhancement solution. Because the available
 oxygen level was considered critical to maintaining a
 rapid rate of degradation, the oxygen-enhancement
 solution was added continuously.  An activated
carbon system was utilized  for further reduction of
residual hydrocarbons in the groundwater in the
final step of remediation. The dissolved hydrocarbon
levels were reduced to less than 10 ppb (Brenoel and
Brown, 1985,1984).
                                               45

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Figure 27.    Houston Chemical Co. response actions (EPA/540/2-84/002b, 1984).
                         Houston Chemical Co.
                         Response Actions
                                                 Hwy. 63
            Spillway
                                                     Service
                                                     Road
      Carbon Filtration
                                                                        Ruptured Tank
                                                                 Main Flow of Oil
              Decontamination Trailer
                Equipment Trailer
                                                    On-Site Lab


                                                 Command Post

                                               Kitchen
Engineered Processes to Achieve Reduction

Anaerobic treatment of hazardous  wastes has not
been widely used in above ground reactors or in situ.
All anaerobic biological treatment processes achieve
the  reduction of organic matter to methane  and
carbon dioxide in an oxygen-free environment. This
is accomplished by using cultures of bacteria which
include facultative  and  obligate  anaerobes.
Anaerobic bacterial systems include hydrolytic
bacteria (catabolize saccharides, proteins, lipids);
hydrogen producing acetogenic bacteria (catabolize
the products of hydrolytic bacteria, e.g.,  fatty acids
and neutral end  products);  homolactic bacteria
(catabolize multicarbon compounds to acetic acid);
and methanogenic bacteria  (metabolize  acetic and
higher fatty acids to methane and  carbon  dioxide).
The strict anaerobes  require totally oxygen-free
environments and oxidation reduction potentials of
less than -0.2V. Microorganisms in this group are
commonly referred to as methanogenic consortia and
are found in anaerobic sediments or sewage sludge
digesters. These organisms play an important ro!0 in
reductive dehalogenation reactions,  nitrosamine
degradation, reduction of epoxides to olefins,
reduction of nitro groups, and ring fission of aromatic
structures.
Technology Description: Available anaerobic
treatment concepts are based on such approaches as
the classic well-mixed system, the two-stage system
and the fixed bed. In the well-mixed digester system,
a single vessel is used to contain the wastes being
treated and all bacteria must function in that
common environment. Such systems  typically
require long retention times and the balance between
acetogenic and methanogenic populations is easily
upset. In the two stage approach, two vessels are used
to maintain separate environments, one optimized for
the acetogenic bacteria (pH 5.0), and  the other
optimized for the methanogenic  bacteria (pH 7.0).
Retention times  are  significantly lower and  upsets
are uncommon in this approach.  The  fixed  bed
approach  (for  single or  2-staged systems) utilizes
inert solid media to which the bacteria attach
themselves and low-solids  wastes are pumped
through columns of such bacteria-rich media. Use of
such supported cultures allows reduced retention
times  since  bacterial  loss  through washout is
minimized. Organic  degradation efficiencies can be
quite high. A number  of proprietary engineered
processes based on these types of systems are actively
being marketed, each with distinct features but all
utilizing the fundamental anaerobic conversion to
methane and carbon dioxide.
                                                 46

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 Applicability/Limitation: These processes are used to
 treat aqueous wastes with low to moderate levels of
 organics.  Anaerobic digestion can handle certain
 halogenated organics better then aerobic treatment.
 Stable, consistent operating conditions must be
 maintained. Anaerobic degradation can take place in
 native soils but when used as a controlled treatment
 process, an air-tight reactor  is  required. Since
 methane and CC>2 gases are formed, it is common to
 vent  the  gases or  burn  them in flare systems.
 However,  volatile hazardous  materials could readily
 escape via such gas venting or flare systems. Thus,
 controlled off-gas burning is required. Alternatively,
 depending on the nature of the  waste to be  treated,
 the off-gas could be used as a source of energy.


 To date,  the logistics for  achieving controlled
 anaerobic  conditions for in-situ surface treatment
 have not been developed. In the subsurface
 environment, it has been shown  that anaerobic
 conditions  can be  achieved   after  aerobic
 biodegradation has depleted the oxygen. Anaerobic
 conditions can  be  controlled in above-ground
 reactors.  Thus  aqueous  waste streams can be
 anaerobically biodegraded whether in a reactor or in
 situ.  Soils  can also be anaerobically treated in an
 above ground reactor. The amount of oxygen present
 in subsurface soils and surface soils cannot be easily
 controlled, therefore anaerobic treatment is not
 generally appropriate.


 Residuals  Produced: Some  biomass is produced
 which will require disposal. The disposal practices
 required will depend on site-specific requirements.


 Corrective Action Application: At the Turi Landfill in
 Orange County,  New York, bench-scale studies at
 room temperature were conducted for the anaerobic
 treatment  of sanitary landfill leachate. Leachate
 collected directly from the Turi landfill site was used
 in test runs conducted in  continuous operation for
 more than 6 months.  Highly variable characteristics
 of the leachate used in the study was exemplified by
 CODs  ranging from  2,000  to 35,000 mg/€, BOD5s
 from 1,800 to 24,000 mg/€, and  ammonia nitrogen
 from 50 to  500 mg/€. Concentrations of detectable
 priority pollutants were also found in the leachate.
 An  anaerobic fixed-film reactor  (with a volume of
 5.78 gal and with  a  controlled rate  of sludge
 recycling)  was operated with upflow feeding at
 organic loadings between 0.51  and 5.46 Ib COD/ft3-
day and hydraulic detention times of 6.9 to 10.3 days
 (Mureebe et al., 1986). The test runs resulted in
filtered COD removals  from 92  to 94 percent,
unfiltered BOD5  removals of 90  to 94 percent, and
ammonia removal from 40 to 50 percent.
  Thermal Processes for Corrective Action

  What is Incineration?

  Corrective Action utilizing incineration can be
  applied to most organic-bearing wastes under various
  conditions. Wastes may be burned which contain
  relatively high water content, are largely inorganic
  in nature  (i.e., they possess high ash content), or are
  in the solid or semi-solid state. The primary question
  is: When should incineration  be chosen  for
  application as opposed to other technologies? To
  decide whether incineration is the best technology for
  a specific  waste, consideration must be given to the
  following issues:

     1.  Limitations which arise from the quantity or
        nature of the waste;
     2.  The environmental impact  of incineration,
        including stack and fugitive emissions;
     3.  The requirements for disposal of residues,
        i.e., ash and air pollution control (APC)
        residues;
     4.  Permitting issues.

 Incineration is an oxidative process which is used for:

     •   detoxification and sterilization
     •   volume reduction
     •   energy recovery
     •   by-product chemical recovery

 The incineration process may be viewed as consisting
 of four parts: (1) preparation of the feed materials for
 placement in the incinerator (pretreatment),  (2)
 incineration or combustion of  the material in a
 combustion chamber, (3) cleaning of the resultant air
 stream by air pollution  control devices (APCDs)
 which are suitable for the application at hand, and (4)
 disposal of the residues from the application of the
 process (including ash, and air pollution control
 system residues).


 Applicability Based on Waste Type
 Thermal processes are typically used for highly toxic
 waste or highly concentrated organic wastes. If the
 waste contains PCB, dioxins, or  other toxic
 substances, incineration should be chosen in order to
 assure destruction. If the wastes contain greater than
 1000 parts per million of halogens  (chlorinated
 materials), it would probably be desirable to select
 incineration of these wastes, after consideration of
 other options. In any  case,  a  material may  be
 incinerated or used as a fuel if the  heat content is
 greater  than 8500 BTUs per pound or, if between
 2500 and 8500, it may be incinerated with auxiliary
fuel. The waste components of concern are halogens,
alkali metals and heavy metals.
                                                47

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Applicability Based On Waste Form

Incineration processes are  available to  destroy
organics in liquids, solids/sludges, soils and gases.;


Selection Strategy
Simple  strategies (as shown in Figures 28 and [29)
exist for evaluating incineration as an'option, given
the waste's  characteristics. This decision logic  will
assist in planning for possible use of incineration for
hazardous waste applications. If the wastes contain
highly toxic substances (e.g., dioxins), or compounds
of special interest such as PCBs, the incineration or
destruction  option  is an attractive one (the  first two
decision diamonds on Figure 28). If wastes contain
high concentrations of halogens or recoverable heat
value  (the next  two decision diamonds),  the
possibility for recovery and/or alternate pretreatment
should  be examined. For  this option, the series of
boxes to the right of the  diagram should  be used.
Finally, waste with low-heat value  could be burned
with supplemental fuel. Thus, the process shown on
Figure 29 may be used  to evaluate incineration
among the treatment technologies available.  If
incineration is selected, the next step is the selection
of the type of combustion  device. The physical form,
metal content, and water content  are the major
considerations for the  selection. Pretreatment
methods exist for wastes prior to incineration.

Thermal  Processes and Their Application
Once the decision is  made to incinerate'the material,
 the type  of incinerator which is selected is largely
dependent  on the matrix in which the  waste is
 located. Table 10 indicates the application of various
 thermal processes for liquids, solids/sludges, soil and
 gases.                                       i

 Incineration of Liquids
 The types of incinerators which can be employed for
 incineration of liquid wastes include:

     •  Liquid injection furnaces
     •  Plasma arc incinerators
     •  Rotary  kilns   (discussed  under  the
        incineration of solids)

 Liquid Injection

 Technology Description: Liquid waste material  is
 introduced to the combustion chamber by means  of
 specially designed nozzles.  Different nozzle designs
 result in various droplet sizes which mix with air and
 fuel as needed. Following combustion,  the resulting
 gases are cooled and treated to remove particulates
 and to neutralize acid gases. Pretreatment (such  as
 blending) may be  required for feeding some wastes to
 specific nozzles in order  to provide efficient mixing
with the oxygen source and to maintain a continuous
homogeneous waste flow. In general, the more finely
atomized liquids will combust more rapidly and more
completely. Operating temperatures range from 1200
to 1300°F and the gas residence time ranges from 0.1
to 2 seconds. Typical heat output ranges from 1 to 100
MMBtu/hr.  A typical configuration for a liquid
injection incinerator is presented in Figure 30.

Applicability/Limitations: Liquid injection incin-
eration can be applied to all pumpable organic wastes
including wastes with high  moisture content. Care
must be taken in matching waste (especially
viscosity and solids content) to specific nozzle design.
Particle  size is a relevant consideration so that the
wastes do not clog the nozzle. Emission control
systems will probably be required for wastes with ash
content above 0.5 percent (particulate control) or for
halogenated wastes (acid gas scrubbers).

Residuals Produced:  Liquid injection incinerators
produce ash which may require application of a post
treatment technology prior to disposal. The by-
products from the emission control devices may also
require further treatment prior to disposal.
 Plasma Arc
 Technology Description: The developmental plasma
 arc process functions by contacting the waste feed
 with a gas which has been energized into its plasma
 state by an electrical discharge. The plasma torch
 acts as one electrode and the hearth at the bottom of
 the reactor acts as the second electrode. The
 discharge  of electricity between the two electrodes
 causes the centerline temperatures in the plasma to
 reach 9000°F. A small amount of gas is introduced
 into the centerline region and is ionized. The ionized
 gas molecules transfer energy fco the waste to cause
 pyrolysis of the waste. Since the process is pyrolytic,
 the scale  of the equipment Is small, especially
 considering the high  throughput rates. This
 characteristic makes it potentially attractive for use
 as a mobile unit. Gaseous emissions (mostly Hg, CO),
 acid gases in the scrubber and ash components in
 scrubber  water are the residuals.  The system's
 advantages are that  it  can  destroy refractory
 compounds and typically the process has a very short
 on/off cycle. The system components for the plasma
 arc process is presented in Figure 31.

 Applicability: This  process is applicable to  liquid
 (pumpable) organic wastes and finely  divided,
 fluidizable sludges. It may be particularly applicable
 to the processing  of liquid wastes with  a. high
 chlorine, pesticide,  PCB  or dioxin content.  Sludges
 must be capable of being fluidized by the addition of a
 liquid. Waste streams must be free of (or preprocessed
 to remove) solids, which prevent satisfactory
 atomization.
                                                  48

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Figure 28.    Conceptual strategy for determining burnability.


                                                   Start
                                             Does Waste Contain
                                              Dioxins or Furans?
                                             Does Waste Contain
                                              >50 ppm PCBs?
Identify all State-of-the
   Art Disposal and
  Treatment Options
                                            Does Waste Contain
                                                >1000 ppm
                                                Halogens?
 Assess Relative Hazard
 to HHE for Each Option
Compared to Incineration
                                              Is the Waste a
                                               Characteristic"
                                                 Waste?
  Estimate Costs of Each
 Option Having Acceptable
     "Hazard" Level
                                            Is Heat Content (as
                                             Received) >8500
                                                 BTU/lb?
                      Scinerate or  \
                      se as Fuel   )
                                             Is Heat Content (
                                             Received) Between
                                              2500 and 8500
                                                 BTU/lb?
  Use Lowest Cost
 Acceptable" Option
                Incinerate with   >>
                 Auxiliary Fuel   )
                                                     49

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Figure 29.   Pretreatment option logical decision flow chart.
                                                                          Other
                                                                       Alternatives
           Is Gross Physical
              Form O.K.?
                                            Modify Physical
                                            Form as Needed
                                              Dewatenng
                                                Process
Is Moisture Content
    Too High?
                                             Solids Removal
                                                Process
Is Solid Content Too
      High?
                                            Metal Removal/
                                               Reduction
                                               Process
 Is Metals Content Too
        High?
                                             Augment with
                                               High BTU
                                               Waste or
                                             Auxiliary Fuel
  Is BTU Content Too
        Low?
                                                                                 ©
                                                                                   I
                                                                     Estimate Probable Emissions
                                                                          -Bottom Ash
                                                                          -Fly Ash
                                                                          -Scrubber Waters
                                                                          -Paniculate Emissions
                                                                          -Gaseous Emissions
                                                                                Assemble List of All
                                                                                Pretreatment Residues
                                                                                     -Liquids
                                                                                     -Solids
                                                                                     -Sludges
                                                                                 Identify Bat for Treatment/
                                                                                 Disposal of All Residues
                                                                                 (Incinerator and Pretreatment)
Perform Composite Risk
Assessment for All Emissions
and All Disposal Residues
                                                                                 Assess Total Process Cost for
                                                                                 Incineration with Pretreatment
Compare Cost "Effectiveness"
with Other
Incineration/Pretreatment
Combinations or Other
Competing Technologies
I                                                                                         Use Most Cost
                                                                                         Effective Option
                                                           50

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 Table 10. Incineration Type for Various Waste Matrices
 	    Liquids Solid/Sludges  Soil   Gases
  Liquid injection incinerator   x
  Plasma Arc             x
  Rotary Kiln                      x        x
  Fluidized Bed            x       x
  Circulating Bed                   x
  Infrared                        x        x
  In-situ Vitrification                          x
  Afterburners                                   x


 Residuals  Produced: The plasma arc process
 produces ash which may require post treatment to
 make it suitable for  disposal. The  wet scrubber
 blowdown may require treatment prior to disposal.


 Solids/Sludges

 The thermal processes  applicable to detoxify organics
 in a solid/sludge matrix include the following
 incinerators:

    •   Rotary kiln
    •   Fluidized bed
    •   Circulating bed
    •   Infrared


 Rotary Kiln

 Technology Description: A rotary kiln incinerator is
 essentially  a long, inclined tube  that  is rotated
 slowly. Wastes and auxiliary fuels are introduced to
 the high end of the kiln and the rotation constantly
 agitates (tumbles) the  solid materials being burned.
 This tumbling causes a great amount of solids mixing
 and allows for improved combustion. Rotary kilns are
 intended primarily for  solids combustion, but liquids
 and gases may be co-incinerated with solids. Exhaust
 gases from the kiln pass to a secondary chamber or
 afterburner for  further oxidation. Ash residue  is
 discharged and collected at the low end of the kiln.
 Figure 32 illustrates a rotary kiln system.

 Applicability/Limitations: Most types of solid, liquid,
 and gaseous organic waste or a mixture of these
 wastes can be treated with this technology. Explosive
 wastes and wastes with high inorganic salt content
 and/or heavy metals require special evaluation. This
 operation can create  high particulate  emissions
 which require post-combustion control.

Residuals Produced: Exhaust gases require acid gas
 and particulate removal through the use of a gas
scrubber and the ashes may require  solidification
before landfilling.

Corrective Action Applications: Case  1 - The U.S.
Army Toxic and Hazardous  Materials Agency
 (USATHAMA) completed a trial burn of explosive,
 contaminated soil in a rotary kiln (Noland, 1984).
 Soil contaminated from red and pink water lagoons
 was successfully burned. A transportable rotary kiln
 system was set up. The technology by Therm-All,
 Inc., had been used in industry for destruction of solid
 wastes. The normal screw feed system was not used,
 due to fear of a soil explosion during the extruded
 plug feed process. Therefore, the soil was placed in
 combustible buckets and individually fed by a ram
 into the incinerator. The feed rate was 300 to 400
 Ib/hr and the operational temperature was 1200° to
 1600°F in  the kiln and 1600°  to  2000°F  in the
 secondary chamber.

 A ORE of 94.99 percent was reported. The flue gases
 were cooled in a heat exchanger prior to entering a
 baghouse for particulate emissions control.

 Case 2 - A mobile rotary kiln incinerator was used at
 the Sidney Mines site, Hillsborough County, Florida,
 to burn nonhazardous oil-contaminated sand and
 sludge (Hatch,  1985).  The site did  not  require a
 RCRA permit since the waste matrix passed the EP
 toxicity test and  was not hazardous. The dry
 processed soil was captured in a bin and tested by the
 EP toxicity method for leachable heavy metals prior
 to disposal  at the nearby county landfill. The flue
 gases were cooled by a boiler prior to entering a water
 quench and steam ejector particulate system. The
 boiler  generates  steam to  operate the particulate
 emissions control ejector. The steam ejector also
 serves as the source and regulator for the negative
 draft through the combustor, and thus the  system
 does not have an induced-draft fan.

 The incinerator processed about 2.25 tph due to the
 high thermal value of the oil.  The  system could
 handle 4 to 6 tph of low-energy soils. The  system
 experienced the following problems:

    •  clogging of front-end waste feed equipment,
    •  loss of refractory bricks sooner than expected,
       and
    •  carry-over of fine solids into the  horizontal
       secondary chamber and restriction of the flue
       gas flow.


 Fluidized Bed

 Technology Description: Fluidized bed incinerators
 utilize a  very turbulent  bed of inert granular
 material (usually sand) to improve the transfer of
 heat to the  waste streams to be  incinerated. Air is
blown through the granular bed materials until they
are "suspended"  and able to move  and mix in a
manner similar to a fluid, i.e., they are "fluidized'Mn
this  manner, the heated  bed particles come in
intimate contact with the wastes being burned. The
process requires that the waste be fed into multiple
injection ports for successful treatment. Advantages
                                                 51

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Figure 30.   Liquid Injection Incineration system
                                                                            Flue Gas
                                   Steam
    Liquid .
    Waste
   Fuel
     Air-
                 i i   Incinerator
                                                                   Acid
                                                                  Solution
                                  Salt
                                 Solution
of this technology include excellent heat transfer to
the material being incinerated and a long solids-
retention time. An off-shoot of this technology is a
circulating bed combustor. The configuration of a
fluidized bed reactor is presented in Figure 33.
Applicability/Limitations: Fluidized beds require
frequent attention for maintenance and cleaning
purposes. This treatment is ideal for slurries and
sludges but not for bulky or viscous wastes. The
waste particles should be of a certain size and be
homogeneous. Wastes must have a low sodium
content and a low  heavy metal content. Some
refractory wastes may not be fully destroyed since
these units operate at low combustion temperatures
(750°tolOOOeC).
 Residuals Produced: Fluidized bed incineration
 produces no separate ash as such, but solids are
 carried over in the gas stream and will require
 removal.  Residuals from the air pollution control
 devices may require additional treatment prior to
 disposal.


 Corrective Action Application: Fluidized bed
 incineration has been used to incinerate municipal
 wastewater treatment  plant sludge, oil  refinery
 waste, some pharmaceutical  wastes, and  some
 chemical wastes  including phenolic  waste, and
 methyl methacrylate. Heat recovery is possible.
Circulating Bed

Technology Description: The circulating bed
combustor (Figure 34) is  designed to be an
improvement over conventional fluidized beds. The
system operates at higher velocities and  finer
sorbents than fluidized bed systems. This permits a
unit that is more compact and easier to feed. The unit
also produces lower emissions and  uses less sorbent
materials than the fluidized bed systems. No off-gas
scrubber  is  necessary  in the circulating bed
combustor and heat can be recovered as an added
benefit. The key to the high  efficiency of the
circulating bed combustor is the high turbulence that
is achieved within the combustor. This feature allows
efficient destruction of all types of halogenated
hydrocarbons including PCBs and other aromatics at
temperatures less  than 850°C.  Acid gases are
captured within the combustion chamber  by
limestone in the bed.  A baghouse is  needed for
particulate control.  Compounds  containing high
levels  of phosphorus, sulfur, cyanide,' etc. can be
processed with low emissions of NOX, CO and acid
gases.  In addition  to  the  turbulence, a  large
combustion  zone  with  uniform  and  lower
temperature throughout also contributes to high
efficiency. The circulating bed combustor also
features longer residence time of  the combustibles
and sorbents in the combustion zone.

Applicability/Limitations: The system is capable of
treating solids, sludges,  slurries  and  liquids. The
high degree of turbulence a.nd mixing ensures
treatment of a wide variety of wastes. The waste
                                                52

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  Figure 31.   Schematic of plasma arc system.

                        Process Water
                                                                    Off Gases to Flare
                                                                         n
                Power
                 Cooling Water
                                                                                         Emergency
                                                                                         Carbon
                                                                                         Filter
                                                                                Gas Chromatograph
                                                                                Mass Selectivity Unit
                                                                                           Laboratory
                                                                                            Analysis
                                                                                           Equipment
                                                                                   Gas Chromatograph
                                                                                     Salt Water to Drain
             Source: Westinghouse Plasma Systems

 however, must be fairly homogeneous in composition
 when fed  to the combustor, since it is usually
 introduced at only one location. An additional benefit
 of the circulating bed combustor is the possibility of
 heat  recovery. The combustion chamber can be of
 "waterwall" construction.

 Residuals Produced: Circulating bed incinerators
 produce  no ash. Solids are carried over in the gas
 stream and require removal. Residuals from the air
 pollution  control device  may  require further
 treatment prior to disposal.

 Corrective Action Application: Circulating fluidized
 bed incinerators are ready for full-scale testing under
 the EPA SITE Program.  A unit is now in the RCRA
 permitting process.


 Infrared

 Technology Description:  Infrared radiators can be
used  as  the heat  source in the  destruction  of
hazardous waste. This system (Figure 35) is made up
of a primary chamber consisting of a rectangular
carbon steel box lined with layers of a light weight,
 ceramic fiber blanket. Infrared energy is provided by
 silicon carbide resistance heating elements. The
 material to be processed is conveyed  through the
 furnace on a woven wire belt. Solids are pyrolyzed on
 the hearth. Sufficient air (or oxygen) is introduced to
 fully combust the off-gases. When the waste reaches
 the discharge end of the furnace it drops off the belt
 into a hopper. Advantages include a quiescent
 combustion zone, which results in low particulate
 emissions; reduced  gaseous pollutant emissions; low
 fossil fuel  usage; and up to 50 percent operational
 turndown capacity.  This system allows a high degree
 of control, and long-residence times for solids are
 achievable.

 Applicability Limitation: This technology is used
 primarily to treat solids, sludges and contaminated
 soils, but liquid or gaseous injection systems are
 available.
So//s

Applications of thermal processes to contaminated
soils are somewhat limited. Two processes, rotary
                                                 53

-------
Figure 32.   Rotary kiln Incineration system.
                                                                                   Steam
    Ram, Auger
                                                                               Concentrated
                                                                               Brine Solution
 kilns and in-situ vitrification, offer a mechanism to
 detoxify organic contaminated soils.

 Rotary kilns, as described previously, can be used to
 incinerate materials which can be excavated and fed
 into the kiln. Vitrification is a process, which can be
 used without removing  the soil and is described
 below.

 Vitrification
 Technology Description:  Vitrification is a  process
 whereby hazardous  wastes are  converted into a
 glassy substance  by means of very  high
 temperatures. The process is carried out by inserting
 large electrodes into contaminated soils, which must
 contain significant levels  of silicates. Graphite on the
 surface connects the electrodes to the soil.  High
 current of electricity passes through  the electrodes
 and soil. The resultant heat in the soil causes a melt
 that gradually works downward  through the  soil.
Some organic contaminants are volatilized  and
escape from the soil surface and must be collected by
a vacuum system. Inorganics and some organics are
trapped in the melt, which, as it cools, becomes a form
of obsidian or very strong glass.  When the  melt  is
cooled, it forms a stable noncrystalline solid.

Applicability/Limitation: Vitrification was originally
tested as a means of solidification/immobilization of
low level radioactive materials. It may also be useful
for forming  barrier walls. This latter  use needs
testing and evaluation to determine how uniform the
wall would be and to evaluate the stability of the
material over a period of time.

Residuals Produced: Off-gases from  the melting
require treatment for volatile organics.

Corrective Action Application; This technology is
currently being evaluated under the  Superfund
Innovative Technology Evaluation (SITE) Program.
                                                   54

-------
Figure 33.    Fluidized bed reactor.
                                                                Sight Glass
                  Exhaust
                 Pressure Tap
                  Access
                  Doors
                                                                                                   Preheat
                                                                                                       Burner
                                                                                               Thermocouple
                                                                                              Fluidized
                                                                                              Sand
                                                                                                    Sludge
                                                                                                    Inlet
                                                                                               Fluidizing
                                                                                               Air Inlet
                                                             55

-------
Figure 34.    CIrculaIng fiuidized bed boiler.
                                        Convection
                                          Pass
                                          _  Flue
                              4-Recycle  ^^ Gas
Secondary
Heat Exchanger
   (Optional)
           Primary
             Air
   Figure 35.    Procass Itow diagram of infrared incineration system.
                                                                                          Material Processing/De-Watering

                                                                                                     _a
                                                               Secondary Combustion
                                                                    Chamber
                                                                                                        Feed Metering
11^0 	 *• <2==3~" 	 *
t,7~u .. — -=c 	 — 	
lIQJ 	 1 	
-ft — II
^_ ^J -»—

1

u

                                          Ash Discharge
                                                                  Primary Combustion Chamber
                                                     Source: Shirco Infrared Systems, Inc.
                                                               56

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 References

 Brenoel, M. and R.A. Brown. Remediation of a
   Leaking Underground  Storage  Tank with
   Enhanced Bioreclamation. In: Proc. 5th National
   Symposium and Exposition on Aquifer Restoration
   and Groundwater Monitoring, National  Water
   Well Association, Worthington, Ohio, 1985. pp.
   O« i.

 Hatch, J. and E. Hayes. "State-of-the-Art Remedial
   Action Technologies Used for  the Sydney Mine
   Waste Disposal Site Cleanups,"  In: Management of
   Uncontrolled Hazardous Waste  Sites Proceedings
   Washington, D.C., 1985, pp. 285.

 Irvine,  R.L., S.A. Sojka  and J.F.  Colaruotolo.
   Enhanced Biological Treatment of Leachates from
   Industrial Landfills. Hazardous Waste Vol 1 No
   1,1984. pp. 123-135.

 Mureebe, A.K., D.A. Busch and P.T. Chen. Anaerobic
   Biological Treatment of Sanitary  Landfill
   Leachate. In: Hazardous Wastes and Hazardous
   Materials, Atlanta, Georgia, 1986.

 Noland, J. and W. Sisk. "Incineration of Explosives
   Contaminated Soils," In: Management of
   Uncontrolled Hazardous  Waste Sites Proceedings
   Washington, D.C., 1984, pp. 203.

Nyer, E.K. Innovative Biological Treatment of
   Contaminated Groundwater. In: First  National
   Outdoor  Action  Conference on  Aquifer
   Restoration, Groundwater Monitoring, and
   Geophysical Methods, May, 1987.
 Skladany, G.J., J.M. Thomas, G. Fisher and R.
   Ramachandran. The Design,  Economics and
   Operation of a Biological Treatment System for
   Ketone Contaminated Ground and Solvent
   Recovery Process Waters. Presented at the 42nd
   Annual Purdue Industrial Waste Conference,
   Purdue University, West Lafayette, Indiana, 1987.
 U.S. Environmental Protection Agency. Case Studies
   No. 1-23: Remedial Response at Hazardous Waste
   Sites, EPA/540/2/84-002b, March, 1984.
U.S. Environmental Protection Agency. Case Studies
   Addendum 1-8: Remedial Response at Hazardous
   Waste Sites., Office of Research and Development
   Cincinnati, Ohio, EPA/540/2-88-001, April 1988
U.S. Environmental Protection Agency. Remedial
  Action at Waste Disposal Sites, EPA/625/6-85/006
  October, 1985.
Ying, W.C., R.R. Bonk and S.A. Sojka. Treatment of
  Landfill Leachate in Powered Activated Carbon
  Enhanced Sequencing Batch Bioreactors. In: Proc
  of the 18th Mid-Atlantic Ind. Waste Conference,
  Technomic Publishing Company, Inc., Lancaster!
  Pennsylvania, 1986.
                                             57

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                                           Chapter 6
                       Pretreatment and Post Treatment Options
 Once the primary treatment alternatives have been
 identified for the detoxification of the waste or waste
 stream,  other  treatment technologies may be
 required to prepare the waste for treatment.
 Similarly, additional treatment technologies may be
 required to prepare  residues from  the  treatment
- process for ultimate disposal. As shown in the review
 of biological processes, some  technologies (e.g., pH
 adjustment) were needed to permit other technologies
 to proceed. Physical separation techniques are
 frequently required to prepare a waste for treatment.
 These pretreatment technologies are directed toward
 concentrating or sizing the waste to  facilitate
 treatment. Furthermore, most treatment processes
 produce residues which  may require additional
 treatment before land  disposal. Solidification/
 stabilization processes are frequently used as post-
 treatment technologies to immobilize hazardous
 constituents in chemical sludges and incinerator ash.
 These solidification/stabilization technologies can
 also be  applied to high volume, low toxicity wastes
 without treatment by other technologies.

 Separation Techniques (Pretreatment
 Options)

Most treatment options for detoxifying the hazardous
constituents from RCRA facilities  must have a
uniform feed to the process. However, the media in
which hazardous constituents are  located are not
generally homogeneous. Thus,  some form of
pretreatment of the waste or waste medium will
probably be required to prepare the waste for further
treatment by chemical, biological or thermal means.

A Separation Strategy

With few exceptions, treatment technologies are
limited to some extent by the size of the material that
they are able to process. These limitations can apply
to the throat of the feed devices, the inner workings of
the equipment, the treatment mechanisms, or the
process  elements. To  make  these  remedial
technologies efficient and cost effective, separation
techniques are used to make the feed stream uniform
 or to isolate specific contaminants from the waste
 stream.

 In developing  a separation strategy,  the  size
 distribution of the components found in the
 contaminated medium can be used as a starting
 point. As an initial step, debris (such as rocks, etc.)
 can be separated from the remainder of the waste.
 After the debris is  removed,  other separation
 techniques can be employed to concentrate the waste
 further or physically  manipulate the waste into a
 form suitable for treatment.
 Debris Separation

 In order to develop measures for removal of debris
 from the waste matrix, the general types of debris
 anticipated need to be identified. A composite list,
 based on debris found at 29 Superfund sites, was
 developed. The list includes cloth, glass, ferrous
 materials, nonferrous  materials,  metal objects,
 construction debris, electrical devices, wood existing
 in a number of different forms, rubber, plastic, paper,
 etc., as presented in Table 11. Similar types of debris
 would be expected at RCRA sites.

 Debris with particularly good absorbent qualities
 such as wood,  some paper products, paper,  cloth
 materials, etc., are good candidates for shredding so
 that they can be included in the remediation process.
 Materials that are not porous and are not adsorbent
 are glass, plastic,  metal objects, some types of
 construction debris, tanks, etc., are good candidates
 for manual or magnetic separation.

 After the debris has been separated or removed, there
 are basically four options available for dealing with
 the debris:

•   Do nothing.
•   Pile it off to the side to be treated later.
•  Shred the material so that it does not interfere
   with the process.
•  Separate it and not include it in the process.
                                               59

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Tablo 11.  Debris Identification
Cloth
 -Rags
 -Tarps
 - Mattresses
Glass
 -Bottles
 -(white, brown, green, clear, blue)
   Windows
Ferrous Metals
 -Cast Iron
 -Tin cans
 -Slag
Nonferrous Metals
 -Stainless steel
 -Aluminum
 -Brass
 -Copper
 -Slag
Metal Objects
 -Autos/vehicles
 -55-galIon drums/containers
  -Refrigerators
  -Tanks/gas cylinders
  -Pipes
  -Nails
  -Nuts and bolts
  -Wire and cable
  -Railroad rails
  -Structural steel
 Construction Debris
  -Bricks
  -Concrete blocks
  -Asphalt
  -Stones and rocks
  -Reinforced concrete pipe
  -Wood
  -Steel beams
  -Asbestos insulation and
    roofing/siding shingles
  - Fiberglass insulation
   - Fiberglass tanks	
Paper
 - Books
 -Magazines
 -Newspaper
 -Cardboard
 - Packing

Plastic
 -Buckets
 -Pesticide containers
 -Six-pack retainer rings
 -Thin plastic sheets
 -Plastic bags
 -Battery cases
Rubber
 -Tires
 -Hoses
 - Insulation
 - Battery cases
Wood
 -Stumps and leaves
 - Furniture
 -Pallets
 - Plywood
  -Railroad ties
 Electronic/Electrical
  -Televisions     !
  -Transformers
  -Capacitors
  -Radios
  Separation Analysis
  In selecting or investigating alternative separation
  and treatment technologies, there are some rules of
  thumb which can be  useful.  For example,
  contamination occurs on the surface of soil particles.
  The smaller the size of the particle, the greater is its
  proportionate surface area; consequently, the smaller
  particles have a  greater  relative  capacity  for
  contamination. In general, in a soil  matrix that
  consists of large particles and small particles,' a high
level of contamination would be expected in the finer
fraction. Experience in site remediation has indeed
shown that to be the case. Making use of this feature
can reduce volumes of waste  to  be treated and
thereby minimize treatment costs.

It should be remembered that while it is generally
true that the heavier contamination is found in the
finer fractions, it is not totally true.  Coarser fractions
can have cracks  where there  is room  for  large
quantities of contamination.

In lagoons where there is liquid  on  the surface and a
highly viscous fluid below the  liquid surface,
separating the water from the waste and sludge may
be appropriate. The expenses for incineration  of the
removed sludge could be greatly reduced by removal
of the water.

The chemical properties of the contaminants have to
be considered when selecting separation techniques.
Some of the liquids are absolutely immiscible in
water, and  if the process stream involves water and
the contamination  is  liquid/liquid,  then the
separation  technique can greatly reduce the volume
of contaminated water. For example, if acetone is the
contaminant of concern, a simple vapor stripping
technique can be effective in making a separation. In
the case of refined oil, which has a solubility limit of
approximately  50 ppm, one of  the  oil/water
separation techniques  could  be  effective.  Some
 general guidelines to consider are:

 •  If the waste stream  has a  high content of fine
    particulate matter then, by isolating particulate
    matter, most of the contamination wotald be
    isolated.

 •   If the chemicals of concern contain  more than
     eight carbon atoms, then they tend to have a high
     soil adsorption.

 In general, when separating two liquids, they must
 be immiscible and have different specific gravities
 before  a separation technique-such  as oil/water
 separation-would be effective. In the case of finely
 dispersed  liquids or finely dispersed solids, if the
 dispersed  material is below one micron in particle
 size, centrifuging should be considered.  The use of
 centrifugal force on the differing  densities of the
 material can facilitate the separation technique.


  Sizing Methodology for Solids
  Once the debris has been removed from the waste
  material, the preparation of the waste for treatment
  can begin. Over  the years, the construction, mining,
  and  manufacturing industries have developed
  various pieces of equipment that are geared for the
  specific purpose  of separating materials and  making
  process  streams uniform.  The raw materials
                                                    60

-------
  themselves can range in size from 1 meter down to 1
  angstrom (10-1° meters) . There are  a number of
  devices that can  be used to separate materials
  depending upon the form of the waste and the particle
  size (Figure 36). These devices utilize a difference in
  size, density, or their  electrical  or magnetic
  properties to make the separation. The use of any of
  these  technologies  or a combination of these
  technologies may be required to prepare the waste for
  further treatment.


  Separation Technologies

  The size  of the particles, the  medium, and the
  contaminant are all important factors in the selection
  of a separation technique. Another important
  consideration in selecting a separation technique is
  whether the process  is intended to  make the waste
  stream uniform or to isolate a portion of the waste
  stream for treatment.


 Scree/75

 The screen is a simple device used for the grading or
 separating of particles by  size.  Vibrating  and
 oscillating screens are used for the same purpose, but
 the passing of the material is enhanced by a vibrator
 or oscillator, respectively. The centrifugal  screen
 enhances the passing of the material by making use
 of centrifugal force and the density of the material.

 Tabling

 Another type of separation that utilizes the difference
 in densities of material is called tabling. The process
 can be performed either wet or dry, with dry tabling
 having the broader particle size range where it can be
 used. The device uses slotted incline  planes, and the
 surface oscillates to move the solids. In the case of wet
 tabling, washing fluid removes the less dense solid
 fractions, and the heavier solids are  collected in the
 grooves and moved to the collection point by the table
 oscillation. For example, dry tabling is  used
 extensively in the coal industry. The undesired
 mineral content of mined coal is much more dense
 than  the actual bituminous, anthracite, or lignite
 fractions of the coal. The ash content of the mineral-
 containing fraction  is much higher than that of the
 coal fraction making separation desirable.

 Another type  of the tabling process is called
 agglomerate tabling. Here, pretreatment is involved
 to precipitate a particular constituent of the material
 so that it can be separated by the tabling process.
 This type of tabling is particularly useful for sludges
 that require pretreatment.

 Cyclones

 Cyclones, hydrocyclones and centrifuges utilize
centrifugal force to separate material of differing
  densities. The principle in the operation of these
  devices is that the heavier materials are thrown to
  the outside, and the lighter materials remain near
  the inside where they can be drawn off (Figure 37).

  Jigging

  Jigging is a separation process in which material of
  similar size but different densities can be separated
  by immersing them in a fluid that is less dense than
  either material. Pulsating the material up and down
  in the fluid is done in such a manner that different
  buoyancy  factors  are  imparted to particles  of
  differing densities (Figure 38). The lighter materials
  separate to the top; the heavier materials settle to the
  bottom. This process can  also be used .to separate
  material of the same density but different particle
  size. The jigging process is used extensively in the
  mining industry, particularly coal mining and
  uranium mining.


  Magnetic Separator

 The magnetic separator is typified by a rotating drum
 surrounded by four stationary magnets. The material
 coming in from the top is composed of magnetic and
 non-magnetic material. As the material falls past the
 drum, the  magnetic field will hold the magnetic
 material in place  until it can drop down  into  a
 separate chute for magnetic materials. The  non-
 magnetic materials, of course, will drop off prior to
 that point and down another chute (Figure 39).

 Oil/Water Separators

 Oil/water separators are another class of devices that
 utilize density to achieve separation. Oil/water
 separators have wide application  at petroleum
 refineries, shipboard bilge water  processing, and
 metal  processing where oil and water emulsions are
 used as lubricants. Most oil/water separators depend
 upon gates or weirs and baffles to effect the oil and
 water  separation without disturbing the operation of
 the rest of the device (Figure 40). This device can also
 include a scraper for solids removal. The effluent is
 discharged into the sewer or a holding basin.

 Another kind of oil/water separator is a coalescing
 system which involves packs of parallel, inclined
 plates. The oil-laden fluid passes down  from top to
 bottom across the parallel plates. As the water passes
 through the plates, oil tends to coalesce on the plates.
 The water is not passed through  the plates  fast
 enough to capture the droplets of coalescing oil.  Due
 to the  buoyant  effect in the water, the coalesced oil
 will go back up the plates. The oil globules escape and
create an oil layer at the top of the device where it can
be skimmed off with a physical skimming device. The
coalescing oil/water separators utilize a sediment
trap so that solids do not get into the parallel plates.
The treated  water, after going through  the plates,
                                                 61

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Figure 36.   Separation techniques for various particle sizes.
    Reverse
    Osmosis
 Hyper
Filtration
                                Micro Filtration
               Ultra Filtration
                    Ultra
                   Centrif.
                Super
              Centrifuge
                                                                     Vibrating Screen
                                                               High Speed
                                                             Vibrating Screen
                                                                  Rod-deck
                                                                   Screen
                                                           _L
                                                              Oscillating Screen
                                                                              Grizzly
                                                                                          Rod Grizzly
                                                                  Sifter Screen
                                                                 	1	
                                                                 T
                                                                  Centrifugal Screen
                                                                Static Sieve
                                                                      _L
                                                           Revolving Filter Screen
        Particle Filtration
            	T
                                                          Wet Classifiers
Centrifuge
                                                                 Revolving Screen, Trommels,
                                                                        Scrubbers
                                                                Jigging
                                                               Hydroseparator
                                                                Wet Tabling
                                                                 Dry Tabling
                                                                   (Coal)  j
                                                                 Agglomeration
                                                                    Table
                                                                Spiral
                                                             Concentration
                                                                       Dense-Medium
                                                                         Separator
      10-9
                10-8
           10-7
                                     10'6
     10-5       10'4

       Meters
                                                                  10-3
                                                                           10-2
                                                                       10-1    10-°
 goes into an outlet chamber where residual oi,l will
 tend to float. The chamber outlet is below the outer
 surface so there is  less likelihood of taking the
 residual oil product to the outlet valve (Figure 41).
 The parallel plate process is not the only type  of
 coalescent equipment that is used.  There  are a
 number of different types of coalescent elements.


 So//s Washing System
 A soils washing system is a system designed  to
 separate  soil into component parts and, in the
 process,  do some  scrubbing  and  washing  of
 contaminants (Figure 42). The one shown is a mobile
 sysbem developed by the EPA. The  waste feed is
 placed in the top hopper. Inside the first chamber is a
 screen section. This is a rotating screen or trommel. It
 has a wedge wire screen, and is designed so  that if
 particles do get slightly caught in the mouth jof the
                                        opening, then they will  not become permanently
                                        wedged between two bars. The wedge allows it to pass
                                        through if it is just barely passable going through the
                                        opening. The material that passes through  is finer
                                        than gravel. The sand, 2 millimeters and finer, goes
                                        into a sump and then goes onto the next device. The
                                        gravel and material larger than 2 millimeters go into
                                        a rotating drum where they tumble around for up to
                                        15 minutes, then are passed to a second screen for a
                                        final washing prior to being discharged down the
                                        chute into a hopper. This produces a gravel mix that
                                        has the majority of its  finer than  2 millimeter
                                        material removed. The  less than  2 millimeter
                                        material then passes on  into this device which is
                                        basically a froth flotation unit with hydrocyclones.
                                        The fluid swirls around inside the apex. The bottom
                                        of the hydrocyclone is where the concentrated slurry
                                        of the  material passes. None of these hydrocyclones
                                        can work beyond a 10 percent slurry.
                                                    62

-------
 Figure 37.   Cyclone.
  Figure 38.   Jigging.
This process removes the coarser fractions in the
hydrocyclones. Hydrocyclones  basically  operate
within the sand region, and if there is material that
is finer than sand (material that passes a 200 mesh
screen), then approximately 100 percent of that
material will pass out the top. The finer fractions and
the wastewater that overflow  from the hydrocyclone
are not treated any further. The contaminants that
reside on the finer fractions adhere fairly well to such
particles,, therefore, it does not make any processing
sense to try and remove them. The coarser fractions
then subsequently move down  into the next cells. The
fluid movement from  right to left and the solid
                                                    Figure 39.   Magnetic separator.
                                                     Non-Magnetic
                                       Magnetic
movement from left to right (as they pass through
each of these hydrocyclones) gives this device its
name,  a countercurrent unit. The coarse fractions
pass through the cleanest water just prior to leaving
the system and the finest fractions traveling away
from the system in the direction of the most
contaminated fluids.


Gas Separation
Gas separation can be achieved with centrifugal
separation techniques. Gas is forced through  a
                                                63

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Figure 40.   API oil/water separator.

             U_  —	Separator Channel      — —
                              	  _j
           Diffusion Device
         (Vertical-Slot Baffle
                \
   Gateway Pier    \
        \         \
        -V
Flight Scraper
Chain Sprocket
    /
Rotatable OIN
Skimming Pipe
       \
       \
Oil-Retention
   Baffle
   s
                                                         Effluent
                                                         Weir and
                                                         Wall
    Forebay
          Slot for
        Channel Gate
           Sludge-Collecting
               Hopper
                                       Efluent Flume        '
                                                      ''
                                                   Etfluent Sewer
                      Sludge Pump
                       Suction Pipe
separation nozzle which is circular in shape.  The
input gas is entered at supersonic speed and the
higher density material tends to go to the outside of
the separation nozzle and the less dense remain on
the inner side. The separation knife will then sheer
the heavy fraction on the outside from the lighter
inner fraction (Figure 43).

Solidification/Stabilization Processes
(Post Treatment  Options)
Solidification/stabilization  technologies  are
techniques designed to be used as final waste
treatment. A major  role of these processes is post-
treatment of residuals produced by other processes
such as incineration or chemical treatment. In some
cases, solidification/ stabilization processes can serve
as the principal treatment of hazardous wastes for
which other detoxification techniques are not
appropriate. High volume, low toxicity wastes (such
as  contaminated soils) are an  example of  this
application.

The intent of solidification/stabilization processes is
to immobilize these  toxic or hazardous constituents
in a waste by:
•  Changing the  constituents into immobile
    (insoluble) forms;
                  •  Binding them in an immobile, insoluble matrix;
                     and/or
                  •  Binding them in a matrix which minimizes the
                     waste material surface exposed to solvent.

                  Often, the immobilized product has a structural
                  strength sufficient to prevent fracturing over time.
                  Solidification accomplishes the objective by changing
                  a non-solid waste material into a solid, monolithic
                  structure  that ideally will not permit liquids to
                  percolate into  or leach materials out of the mass.
                  Stabilization, on the other hand, binds the hazardous
                  constituents into an insoluble matrix or changes the
                  hazardous constituent to an insoluble form. Other
                  objectives  of solidification/stabilization processes are
                  to improve handling of the waste and produce a stable
                  solid (no  free liquid)  for  subsequent use  as a
                  construction material or for landfilling.

                  As  a first  step in the selection process, the
                  applicability  of the various solidification/
                  stabilization processes for specific contaminants can
                  be determined using Table 12. Since these waste
                  treatment systems vary widely in their applicability,
                  cost, and  pretreatment requirements, many are
                  limited as  to the types  of waste that  can be
                  economically processed. Waste characteristics such
                  as organic content, inorganic content, viscosity and
                                                  64

-------
 Figure 41.   Shell corrugated-plate interceptor.
                                                            Oil Globules
                     \\\\\\\\\\\\\\\\
1
M^ *
*
• 9
1
\
\
t <
^r^
                                         Inlet
                                         A
                                                                 \\\\ \\V\\\\\Y\\\\\
                                                                                Sediment Trap
                                                            "^ Packs of Corrugated
                                                                 Parallel Plates
 Treated Water Outlet
      Channel
sL
V^— — Sludge Pit
particle size distribution can affect the quality of the
final solidified product. These characteristics inhibit
the  solidification  process  by  affecting  the
compatibility (or incompatibility) of the binder and
the waste, and the completeness of encapsulation and
development of preferential paths for leaching due to
spurious debris in the waste matrix. Selection of any
particular technique for  waste treatment must
include careful consideration of the intended purpose
for the action, the cost of processing, the increase in
bulk of material produced  and the  changes in the
handling characteristics of the resultant by-products.
The design and  location of any placement area  or
landfill that eventually receives the  treated waste is
also a major consideration in deciding on the physical
properties that will be required of the stabilization
process.

Solidification/stabilization processes are not "off-the-
shelf"  technologies,  thus, it is not unusual for
modifications to  the additives required for a specific
waste. For this  reason, some  pilot testing of the
solidification reagents may be required to develop the
ultimate characteristics desired in the final product.
      As part of the  quality control procedures for
      solidification technologies, raw materials used must
      be checked as well as the waste and the final product.
      The raw materials  may vary from supplier to
      supplier and from batch to batch. In order to achieve
      a consistent solidified product, tests should  be run to
      check raw material inputs and match them to plant
      operations. More important, the waste must be tested
      before processing. To this end, samples are  taken for
      treatability studies during the facility investigation
      as well as during processing of the waste on  a routine
      basis. When an  incoming waste  is received  at a
      solidification treatment facility, it must  be rapidly
      tested for selected parameters  which may  interfere
      with the solidification process. This testing can be
      complicated, and there is little time available to
      match the incoming wastes' characteristics with
      those previously determined  to be acceptable for a
      solidification process designed specifically for the
      waste. The waste characteristics must be consistent
      between shipments (within an acceptable range): if it
      does not meet the requirements, the shipment may be
      rejected on this basis. As a last quality  check, the
      final product must undergo preselected physical and
                                                 65

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Figure 42.   Mobile soils washing system.
  Coo laminated
    Soil in
                                                                             To Vapor
                                                                             Control
   Soil Feed
    Motor
 First
Screen
                                                                               -«— Clean Wash Fluid
             Rotating Drum (2-14 rpm)
                                ^'•'•.';'.•. + 2mm Gravel with Some -2mm•:';


A A L
Second
Screen
\ X


J
ute Slurry
- 2mrn
+ 2m
                Spent Wash Fluid
                                                                                        Clean Wash
                                                                                       Fluid to Cell 4
                                                                                   Clean Soil Slurry
chemical tests, and the results must fall within
acceptable ranges.

Physical and chemical tests of the final product may
need to address two  concerns: (1)  whether  the
solidified waste exhibits any RCRA defined toxicity
characteristics or could be delisted; and (2)  the
potential long term fate of treated materials iii the
disposal environment. Three tests are available
which address the first concern. These are(  the
Extraction Procedure (EP Tox) (40  CFR 261,
Appendix II, 1980) and the Toxicity Characteristic
Leaching Procedure (TCLP) (40 CFR 261, Appendix
II, 1986), and the Multiple Extraction Procedure Test
(40 CFR 261, Appendix II,  January 1989). It is
important to note that these tests are not indicators
of expected leachate quality but of potentials. A
solidified product which cannot pass the  appropriate
test  (EP  Tox or TCLP) would be  subject to
classification as a hazardous waste.
A wide variety of tests may be useful in assessing the
long term fate of a solidified product. An appropriate
                               combination of tests would deprend on the nature of
                               the waste, the treatment technology employed, and
                               the final disposal environment of the treated waste.
                               Performance test methods for a number of these
                               testing procedures are currently being evaluated by
                               the U.S.  EPA  Risk  Reduction Engineering
                               Laboratory in Cincinnati, Ohio. General information
                               is  provided  through  the  Handbook  for
                               Stabilization/Solidification of  Hazardous Wastes
                               (U.S. EPA, 1986).
                               Available Solidification/Stabilization Technologies
                               and Their Application
                               Major    categories   of   industrial   waste
                               solidification/stabilization systems are cement-based
                               processes, pozzolanic  processes (not  including
                               cement), thermoplastic techniques, organic polymer
                               techniques, surface encapsulation techniques, and
                               self-cementing techniques (for high calcium sulfate
                               sludges). Vitrification (discussed previously) can also
                               be considered a solidification process.
                                                 66

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Figure 43.    Separator nozzle.
    Table 12. Applicability of Solidification/Stabilization for Specific Contaminants
Process
Micro-
encapsulation
Asphalt-
based
Polymer-
based
Macro-
enoapsulation
with
polyethylene
Stabilization
Cement-
based
Pozzolanic
Organic
Heavy Metals Solvents3

Applicable Applicable
Applicable Applicable;
impeded
setting11
Applicable Applicable if
contaminant is
adsorbed onto a
solid

Applicable Applicable;
impeded setting
Applicable Applicable;
impeded setting
Solid Orgahics
(excluding
explosives)

Applicable;
contaminant
may act as a
binding agent
Applicable;
impeded setting
Applicable

Applicable
Applicable
Acidic Wastes
(from explosives
manufacturing Oxidants

Applicable if Not applicable
waste is first
neutralized
Applicable Not applicable
Applicable if Not applicable
waste is first
neutralized

Applicable Applicable
(contaminant is
neutralized by
the basic
cement)
Applicable Applicable
Sulfates

Not applicable
Applicable
Applicable

Applicable if an
additive used to
prevent spelling
Applicable
   a May volatilize upon heating.
   b "Impeded setting" does not preclude the existence of an additive that could counteract this effect.
                                                                                                     Source: R.F. Weston
                                                            67

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Cement-based Pozzolan

Technology Description: To understand the cement-
based pozzolan solidification/stabilization process, it
is necessary to first understand the binding material.
Common (portland) cement is produced by firing a
charge  of limestone and clay  or  other silicate
mixtures in a kiln at high temperatures. The
resulting clinker is ground to  a fine powder to
produce a cement that consists of approximately 50
percent tricalcium and 25 percent dicalcium silicates
(also present are about  10 percent  tricalcium
aluminate and 10 percent calcium aluminoferrite).
The cementation process  is  brought about by the
addition of water to the anhydrous cement powder.
This first  produces  a colloidal calcium silicate-
hydrate gel of indefinite composition and structure.
Hardening of the cement is a lengthy process brought
about by the interlacing  of thin, densely packed,
silicate fibrils growing from the individual cement
particles. This fibrillar matrix incorporates the added
aggregates and/or waste into a monolithic, rock-like
mass.

A number of additives (many proprietary) have been
developed for  use with  cement to improve the
physical characteristics and to decrease the leaching
losses from the solidified mass. Experimental work
on the treatment of radioactive waste has shown that
nuclear waste  retention improvements can be
achieved by cement-based stabilization processes
with the  addition of clay or vermiculite  as
absorbents. Soluble silicates have reportedly been
used to  bind contaminants in cement solidification
processes, but this additive causes an increase in
volume  to occur during the  setting of the cement-
waste mixture. A recently proposed modification of
this technique involves dissolving the metal-rich
waste with fine-grained silica at low pH and then
polymerizing the mixture by raising the pH to 7. The
resulting contaminated gel is mixed with cement and
 hardens within 3 days. The  equipment used for the
 cement-based pozzolan process is similar to that used
 in a cement batching plant  as illustrated in Figure
 44.

 Applicability: Most hazardous waste slurried in
 water can be mixed directly with cement, and the
 suspended solids will be incorporated into the rigid
 matrices of the hardened concrete. This process is
 especially effective for waste with high levels of toxic
 metals since at the pH of the cement mixture^ most
 multivalent cations are  converted into insoluble
 hydroxides or carbonates. Metal ions also may be
 incorporated into the crystalline structure of the
 cement minerals that form.  Materials in the waste
 (such as sulfides, asbestos, latex and solid plastic
 wastes) may actually  increase the strength and
 stability of the waste concrete. It is also effective for
 high-volume, low-toxic, radioactive wastes.
The presence of certain inorganic compounds in the
hazardous waste and the mixing water can be
deleterious to the setting and curing of the waste-
containing concrete. Also, impurities such as organic
materials, silt, clay or lignite may delay the setting
and curing of common portland cement for as long as
several days. Dust-like, insoluble materials passing
through a No. 200 mesh sieve (74 X 10-6m particle
size) are undesirable, as they may coat the larger
particles and weaken the bond between the particles
and the cement. Soluble salts of manganese, tin, zinc,
copper and lead may cause large variations in setting
time and significant reduction in physical  strength.
In this regard, salts of zinc, copper and lead are the
most detrimental. Other compounds such as sodium
salts  of  arsenate, borate, phosphate, iodate and
sulfide will retard setting of portland cement even at
concentrations as low as a few tenths of a percent of
the weight of the cement used. Wastes containing
large amounts of sulfate (such as flue-gas cleaning
sludges)  not only retard the setting of concrete, but,
by reacting to form calcium sulfoaluminate hydrate,
cause swelling and spalling in the solidified waste-
containing concrete. To prevent this reaction, a
special low-alumina cement was developed for use in
circumstances where wastes containing high sulfate
levels are encountered.

Advantages: Cement-based solidification systems are
an economically feasible process having the following
advantages:

    (1) The amount of cement used can be varied to
       produce high-bearing  capacities thereby
       making the waste/concrete material a good
        subgrade and subfoundation material.

    (2) Low permeability in the product can also be
        achieved by  varying the amount of cement
        used.

    (3) Raw materials are plentiful and inexpensive.

    (4) The  technology and management  of cement
        mixing and handling is well known; the
        equipment is commonplace and specialized
        labor is not required.

    (5) Extensive drying or dewatering of the waste
        is not required because cement mixtures
        require water in the hydration process, and
         thus the amount of cement added can be
         adjusted to  accommodate  a wide range of
         waste water contents.

     (6)  The system is tolerant  of most chemical
         variations.  The natural alkalinity of the
         cement used can neutralize acids. Cement is
         not  affected by strong oxidizers, such as
         nitrates or chlorates.
                                                 68

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  Figure 44.   Cement-based stabilization process (Roy F. Weston).
                                   Mixing Pump
                                                           (Sodium     J
                                                         Silicate Tank   J
                                                         Stabilized Waste
    (7)  Pretreatment is required only for materials
        that retard or interfere with the setting
        action of cement.

    (8)  Leaching  characteristics can be improved,
        where necessary, by coating the resulting
        product with a sealant.

Disadvantages: Disadvantages include the fact that
relatively large amounts of cement are required for
most treatment processes (but this may partly be
offset by the low  cost of material). The weight and
volume of the final product is typically about double
those of other solidification processes. Uncoated
cement-based products may require a well-designed
landfill for burial. Experience  in radioactive waste
disposal indicates that some hazardous constituents
are leached from the solidified concrete, especially by
mildly acidic leaching solutions.  Extensive
pretreatment and  the use of more expensive cement
types or additives may be necessary for waste
containing large  amounts of  impurities, such as
borates and sulfates which can effect the setting or
curing of the waste-concrete mixture. If ammonia is
present in the waste, the alkalinity of cement drives
 off ammonium ions as ammonia gas. Finally, if
 energy cost increases dramatically, the cost of cement
 will likely follow because cement is  an energy-
 intensive material.

 Corrective  Action Application: At the James River
 site in Virginia, cement-based solidification  was
 performed on kepone-contaminated sediment.
 Testing indicated that the cementitious agents were
 ineffective in reducing kepone concentrations in
 water  leachate (Tittlebaum et al., 1985). This  was
 attributed to  the high pH of the cementitious
 stabilization agents required in the curing process.
 Although  the elevated pH proved to  effectively
 contain heavy metals, it resulted in increasing the
 water  solubility of the kepone  in the sediment
 (Tittlebaum et al., 1985). This example serves to
 show how contaminant-specific, cement-based
 solidification processes are.


 Pozzo/an/c Processes (Not Containing Cement)
 Technology Description:  Waste solidification
techniques  based on lime products usually depend on
the reaction of lime with a fine-grained silica
                                                69

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(pozzolanic) material and water  to  produce  a
concrete-like solid (sometimes referred to  as  a
pozzolanic concrete). The most common pozzolanic
materials used in this solidification  process are fly
ash, ground blast-furnace slag and cement-kiln dust.
All of these materials are themselves waste products
with little or no commercial value. The  use of these
waste products to consolidate another waste is often
advantageous to the processor, who can treat two
waste products at the same time. For example, by
making use of the pozzolanic reaction,  power-plant
fly ash can be combined with flue-gas-cleaning
sludge and lime (along with other additives) to
produce an easily handled solid. Figure 45 illustrates
the configuration of equipment used for this process.

Applicability: Pozzolanic processes are  suitable for
high-volume,  low-toxicity wastes  containing
radioactive materials  or  heavy metals  with an
organic content below 10 percent.


Advantages:  The  advantages  of lime-based
solidification techniques that  produce pozzolanic
concrete are: solidified material produced! has
improved handling and permeability characteristics;
materials required for the process are often very low
in cost and widely available; little  specialized
equipment is required for processing; the chemistry
of lime-pozzolanic reactions are relatively well-
known; sulfate content  of the waste does not cause
spalling or cracking; and extensive dewatering is not
necessary because water is required in the setting
reaction.


Disadvantages: The lime-based systems have many
of the same potential disadvantages  as cement-based
 techniques including: the lime and other additives
 add to the weight and bulk of the resultant product to
 be transported and/or landfilled; uncoated lime-
 treated materials may require specially designed
 landfills to guarantee that the material does not lose
 potential pollutants by leaching; the process is
 temperature sensitive; the waste may  require
 pretreatment; the setting characteristics of the
 pozzolanic concrete are sensitive to organic content;
 and the process has a potential for producing fugitive
 dust emissions.


 Corrective Action Application:  In Massachusetts, a
 municipal wastewater treatment plant  receives a
 number of wastestreams containing heavy metals
 from local industries. When tested, the dewatered
 sludge failed the EP toxicity test. In order to permit
 landfill disposal of the sludge, solidification processes
 were examined. A soluble, silicate-based system,
 developed by Chemfix, was ultimately selected which
 produced a product whose leachate passed the EP
 toxicity test (Sullivan, 1984).
Cement-Pozzolanic Processes

Certain treatment systems fall in the category of
cement-pozzolanic processes and have been in use for
some time outside the U.S. In these systems, both
cement and lime-siliceous materials are used in
combination to give the best  and most economical
containment for the specific waste being treated. In
general, the bulk of the comments  (under both
classifications above) hold for  techniques  using a
combination of treatment materials.


Thermoplastic Microencapsul&tion
Technology Descriptions: The use of thermoplastic
solidification systems in radioactive waste  disposal
has  led to the development of waste containment
systems that can be adapted to industrial waste. In
processing radioactive waste with bitumen  or other
thermoplastic material  (such as  paraffin or
polyethylene), the waste is  dried, heated  and
dispersed through a heated, plastic  matrix. The
mixture is then cooled to solidify the mass.

The process requires some specialized (expensive)
equipment to heat and mix the waste and plastic
matrices, but equipment for mixing and extruding
waste plastic are commercially available. The plastic
in the dry waste  must be mixed at  temperatures
ranging from 130° to 230°C, depending on the
melting characteristics of the material and type of
equipment used.

A variation  of this process  uses an emulsified
bitumen product that is miscible with a wet sludge.
In this process, the mixing can be performed at any
convenient temperature below the boiling point of the
 mixture. The overall mass must still  be heated and
 dried before  it is suitable for disposal. Ratios of
 emulsions to  waste of 1:1 to  1:1.5 are necessary for
 adequate incorporation.

 Applicability: Thermoplastic microencapsulation is
 commonly used for high-toxicity, low-volume wastes
 and is suitable for inorganic and most organic waste.
 In many cases, the waste type can rule out the use of
 an  organic-based treatment  system.  Organic
 chemicals that are solvents for the matrix obviously
 cannot be used directly in the treatment system.
 Strong oxidizing salts (such ass nitrates, chlorates or
 perchlorates) will react with the organic matrix
 materials and cause slow  deterioration. At the
 elevated temperatures necessary for processing, the
 matrix-oxidizer mixtures are extremely flammable.

 Leach or extraction testing undertaken on anhydrous
 salts embedded in bitumen as a matrix indicates that
 rehydration of the embedded compound can occur.
 When the sample is soaked in water, the asphalt or
 bitumen can swell and split apart, thereby greatly
 increasing the surface area &nd rate of waste loss.
                                                 70

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  Figure 45.   Lime-based (pozzolanic) stabilization process (Roy F. Weston).
                                    Pozzolanic
                                      silo
               Waste
     Lime
     silo


1
f
Feeder
units

i
f
                                                                                         -Landfill
                                                                        Stabilized waste
 Some salts (such as sodium sulfate) will naturally
 dehydrate at the temperatures required to make the
 bitumen plastic; thus, these easily dehydrated
 compounds must be avoided in thermoplastic
 stabilization.

 Advantages:  The  major advantages  of the
 thermoplastic-based disposal systems are: by
 disposing of the waste in a dry condition, the overall
 volume of the waste is greatly reduced;  most
 thermoplastic  matrix materials  are  resistant to
 attack by aqueous solutions; microbial degradation is
 minimal; most matrices  adhere well to incorporated
 materials,  therefore, the final product has good
 strength; and materials embedded in a thermoplastic
 matrix can be reclaimed if needed.

Disadvantages:  The principal disadvantages of the
 thermoplastic-based disposal systems are the
following: (1) expensive, complicated equipment
requiring highly specialized labor is necessary for
processing; (2)  the plasticity of the matrix-waste
mixtures may require that containers be provided for
 transportation and disposal of the materials, which
 greatly increases the cost; (3) the waste materials to
 be incorporated must be dried, which requires large
 amounts of energy; (4) incorporating wet  wastes
 greatly increases losses through leaching; (5) these
 systems cannot  be  used with  materials that
 decompose  at high temperatures, especially citrates
 and certain types of plastics; (6) there is a risk of fire
 in working with organic materials such as bitumen
 at elevated temperatures; (7) during heating, some
 mixes can release objectionable oils and odors,
 causing secondary air pollution; (8) the incorporation
 of tetraborates of iron and aluminum  salts  in
 bitumen matrices causes premature hardening, and
 can clog and damage  the mixing equipment; (9)
 strong oxidizers usually cannot be incorporated into
organic materials without the occurrence of oxidizing
reactions (High concentrations of strong oxidizers at
elevated processing temperatures  can  cause  fires.);
and  (10) dehydrated  salts  incorporated  in the
thermoplastic matrix will slowly rehydrate if the
mixture is soaked in water. The rehydrated salt will
expand the mixture causing the waste block  to
                                                71

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fragment thereby increasing the exposed surface
area.

Corrective Action Application: Documentation 0^1 the
application of this technology is limited for RCRA
sites.

Surface Encapsulation
Technology Description: Many waste  treatment
systems depend on binding particles of waste
material together. To the extent to which the binder
coats  the  waste  particles, the wastes  are
encapsulated. However, the systems addressed by
surface encapsulation processes are those in which
the waste has been pressed or bonded together and
then is enclosed in a coating jacket of inert material.
A number of systems for coating solidified industrial
waste  have been examined. In most cases, coated
materials have suffered from lack of adhesion
between coatings and bound wastes, and lack of long-
term integrity in the coating materials.

Applicability: Surface encapsulation (macroeiicap-
sulation)  is appropriate  for  both organic  and
inorganic wastes.

Surface coating of concrete-waste  composites has
been examined extensively. The major problems
encountered have been poor adhesion of the coating
onto the waste or lack of strength  in the concrete
 material containing the waste. Surface  coating
 materials that have been investigated include
 asphalt, asphalt emulsion and vinyl. THowever,  no
 surface coating system for cement-solidified material
 is currently being advertised.

 Advantages: Major advantages of an encapsulation
 process involve the fact that waste materials never
 come  into contact with water, therefore, soluble
 materials (such  as sodium chloride)  can  be
 successfully surface-encapsulated. The impervious
 jacket also eliminates all leaching into contacting
 waters as long as the jacket remains intact.

 Disadvantages: A major disadvantage of surface
 encapsulation is  that the resins required for
 encapsulating are  expensive. The process requires
 large expenditures of energy in drying, fusing the
 binder and forming the jacket. Polyethylene  is
 combustible (with  a  flash point of 350°C) making
 fires a potential  hazard. The system requires
 extensive capital investment and equipment. Skilled
 labor is required to operate the molding and fusing
 equipment.

 Corrective Action Application: TRW Corporation has
 developed one type of encapsulation system (U.S.EPA
 1980). The TRW surface encapsulation requires that
 the waste material be thoroughly dried. The dried
 waste is stirred into an acetone solution of modified
1,2-polybutadiene for 5 min. The mixture is allowed
to set for 2 hr during which time a solid block is
formed.  The optimum amount  of binder for
encapsulation is 3 percent to 4 percent of the fixed
material on a dry-weight basis. The coated material
is placed in a mold, subjected to slight mechanical
pressure, and heated to  between 120° and 200°C to
produce fusion. The agglomerated material is a hard,
tough, solid block. A polyethylene jacket 2.5 mm
thick is used to encapsulate the solid block and
adheres to the polybutadiene binder.

No field tests  or pilot applications of this process have
been performed to date. The product does well in
bench tests in which the  polyethylene jacket remains
intact Destructive bench tests which  grind  the
product (such as the EP Tox or TCLP) defeat  the
purpose of the encapsulating jacket.


Self-Cementing
Technology Description:  Some industrial wastes such
as flue-gas-cleaning sludges contain large amounts of
calcium sulfate and calcium sulfite. A technology has
been developed to treat these types of wastes so that
they become  self-cementing. Usually a small portion
(8 percent to 10 percent by weight) of the dewatered
waste sulfate/sulfite sludge  is calcined under
carefully controlled conditions to produce a partially
dehydrated cementitious calcium sulfate or  sulfite.
This calcined waste is  then reintroduced into the
 waste sludge along with other proprietary additives.
 Fly ash is often added to adjust the moisture content.
 The finished product is  a hard, plaster-like material
 with  good  handling  characteristics  and  low
 permeability.

 Applicability: Self-cementing processes require large
 amounts of calcium sulfate and calcium  sulfite and
 are appropriate for immobilizing heavy metals.

 Advantages: The primary advantage for using a self-
 cementing process is the material produced is stable,
 nonflammable and nonbiodegradable.  There are
 reports of effective heavy me.'tal retention, which is
 perhaps  related to chemical bonding of potential
 pollutants.  Other advantages are: (1) no major
 additives have to be manufactured and shipped to the
 processing site; (2) the process is reported to produce
 a faster setting time and more rapid curing  than
 comparable lime-based systems;  and (3) these
  systems do not require  completely dry waste because
  the hydration reaction uses up water.

 Disadvantages: The disadvantages associated  with
  self-cementing processes include: the  self-cemented
  sludges have much the  same leaching characteristics
  as cement- and lime-based  systems; only  high
  calcium sulfate or sulfite sludges can be used; and
  additional energy is required to produce the calcined
  cementitious  material. The process  also requires
                                                 72

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 skilled labor and expensive machinery for calcining
 waste and for mixing the calcined wastes with the
 bulk waste and the proprietary additives.

 Corrective Action Application: Documentation on the
 application of this technology for RCRA waste is
 limited.

 References

 Tittlebaum, Marty E., Roger Seals, Frank Cartledge,
 Stephanie Engels, Louisiana State University. State
 of the Art on Stabilization of Hazardous Organic
 Liquid Wastes and Sludges. Critical Reviews  in
 Environmental Control, Volume 15, Issue 2,1985.

 Sullivan, Tim, "SESD is Treating Sewage Again -
With Time to Spare", The Salem, Massachusetts,
Evening News - 3, July 1984.  •
 U.S. Environmental Protection Agency, "Guide to
 the Disposal of Chemically Stabilized and Solidified
 Waste", SW-872, Office of Water and Waste
 Management, Washington, D.C., 1980.

 U.S. Environmental Protection Agency, "Handbook
 for Stabilization/ Solidification  of Hazardous
 Wastes", EPA/540/2-86/001.
Federal Register - Extraction Procedures  40 CFR
261, Appendix II, 1980.

Federal Register - Toxicity Characteristic Leaching
Procedure, Revised 40 CFR 261, Appendix II, 1986.

Federal Register - Multiple Extraction Procedure
Test, Revised 40  CFR  261,  Appendix II, January
1989.                                          *
                                              73

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                                           Chapter 7
      Engineering Considerations for Corrective Measures  Implementation
 The Corrective Measures Implementation (CMI)
 phase of the Corrective Action Process can present a
 difficult task for engineers involved in implementing
 the corrective action(s)  selected. Up to this point,
 activities have  been directed  toward  those
 engineering  matters associated  with site
 characterization and remedy selection, along with
 routine interface with the regulatory community. As
 the work  proceeds  into the corrective  measure
 implementation (design and construction) phase, the
 company management becomes more involved in the
 process, primarily as a result of the need to commit
 funds. In addition, the engineer must now come face-
 to-face with the complexities of the site in terms of
 the installation of facilities. Thus, the engineer's
 efforts  are  directed toward  the parallel, yet
 interconnected, activities associated with satisfying
 the regulatory  requirements,  dealing with
 management's needs, and  developing facilities
 consistent with  the  site conditions. Using the
 elements of the Corrective Measures Implementation
 outlined in RCRA Corrective Action Plan - Interim
 Final (U.S. EPA, 1988)  specifically the CMI Plan
 Development, the Corrective Measures (CM) Design
 and CM Construction  the  implications of each
 element can be viewed in the context of conventional
 engineering activities.


 CMI Plan Development

 From an engineering perspective, it is normal
 practice to  identify a project management team and
 project strategy prior to beginning the design phase.
 It is at this point that the methods for handling the
 design,  preparation of specifications, and
 construction are decided. In essence, a plan (although
 not formalized in  great detail)  is defined for the
 design phase and generalized for the construction
 phase.  The  EPA's proposed guidance suggests that
 the management plan for Corrective Actions be
 formalized similar to plans submitted for Superfund
 cleanup projects.

A  community relations plan is suggested for
corrective action projects. For most projects, such
activities are reserved for public relations personnel.
However, because of the technical  aspects of
corrective action projects, engineering attention may
 be required to alleviate public, concern with noise,
 odors and other nuisances associated with corrective
 action activities. It is important to work closely with
 the local residents so  that these problems can be
 identified and handled effectively when they occur.
 For  example, on one stabilization job, a new
 solidifying agent was brought to the site  which
 caused some dusting problems. The dust got on a
 number of neighbor's  cars. Because of the  public
 participation program, the problem was quickly
 identified; a solution was found to prevent the dust
 emissions; and the contractor paid to have all of the
 affected automobiles cleaned. The project was only
 shut down  for one day while the dust collecting
 measure was implemented. A much longer delay
 would have occurred without the presence of a public
 participation  program which  avoided the
 development of antagonism between local residents,
 the contractor, and the company implementing the
 program.

 Corrective Measures Design

 The design phase of an engineering project normally
 consists of the following activities:

    •  Defining the design basis.
    •  Preparing preliminary and detailed design
       drawings.
    •  Development  of  equipment  lists  and
       specifications.
    •  Developing material and energy balances.

 Based on the  in-house engineering capabilities,
 management philosophy, and the complexity of the
 project, there are a number of ways a company may
 wish to approach these  activities. In some cases, a
 turnkey  approach  where an engineering firm'is
 retained  to design and construct  the  required
 facilities  is preferred. In other cases,  the design,
 specification, preparation  and construction
 management  activities are performed by the
 company, and the equipment and construction
 activities are purchased.  However,  it is  not
 uncommon for construction of facilities to begin prior
to the completion of the design. Most companies have
mechanisms  for the routine review of a project at
various phases of completion. These project review
                                              75

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requirements parallel  those of the regulatory
community. For corrective action projects, it will be
necessary to take into consideration the needs of the
regulatory community in the scheduling and
recording of activities as they are performed.

Operations and Maintenance Manuals are typically
developed for most industrial facilities.  The
development of these documents usually takes place
after all equipment is purchased and during the
installation and shake-down of the facilities. These
manuals cover normal operation and maintenance of
equipment, including  troubleshooting instructions
and preventive and routine maintenance needs of the
equipment. The items suggested in the CAP that are
not normally  addressed  by  operation  and
maintenance  manuals are issues  such as  a
description of potential  operating problems which
evolve from human  health and environmental
considerations; a description of alternate operating
and maintenance activities which recognize possible
aspects for system failure; a description of routine
monitoring and laboratory testing; and a safety plan.
For example, machinery that has been contaminated
during remediation of the site  may have to be
maintained  on site  or  decontaminated  prior to
maintenance. Depending on the nature of the work,
the health and safety of the personnel performing
maintenance may  require extraordinary procedures
in order to perform what may otherwise be routine
 tasks (e.g., lubrication of heavy equipment while
 wearing protective equipment).

 Other, engineering considerations which are
 routinely addressed  in  the design phase are the
 development of a project schedule and cost estimate.
 Most companies or contractors for those companies
 have developed construction quality assurance
 programs which are based on good  engineering
 practice and state and local building requirements.
 Regulatory considerations and data  reporting may
 impact on the quality assurance  program and
 construction schedules. The design is based on the
 information generated during the facility assessment
 and the facility investigation. During construction,
 additional information is generated  that may alter
 the process requirements and operating parameters,
 forcing schedule changes.

 In addition to regulatory requirements, the practical
 matters associated with maintaining product and
 personnel flow to  and from operating facilities must
 be addressed. For example, it may be difficult to
 remove a rail spur for remediation of a contaminated
 bed, if the only means to deliver a feedstock into the
 facility or ship a product from the facility is this rail
 line. In-situ flushing or some other  form of non-
 invasive treatment would be required to address such
 a problem. Similarly, personnel access may have to
 be addressed in the  planning for a corrective
 measures program. This is especially true in older or
more crowded facilities. People and material must be
allowed to move around so that operations may
continue at the facility in as normal a fashion as
possible.

Corrective Measures Construction
From an  engineering perspective, the general
corrective measures construction activities identified
in the CAP  conform with typical  construction
management  activities, but are more rigorous. The
planning, inspection, and quality  assurance
activities in the CAP focus on issues of concern to the
regulatory community to ensure that the completed
corrective measures meet or exceed the  cleanup
objectives. In addition to the regulatory needs, the
facility engineer is also concerned with  these issues
from the perspective of  ensuring efficient
construction of facilities, and that  the facilities
installed meet the design specifications, plant safety
requirements, and building codes. As  most
construction projects proceed, a "punch" list of items
requiring completion, modification to  meet safety
codes, or repairs identified during  equipment
checkout is  developed; and  system start-up and
shake-down  procedures are  developed.  Periodic
review and resolution of each item is required before
the construction phase is considered complete.

Another issue that the engineer must consider is the
training of operating personnel. This can be handled
by the contractor or by the equipment supplier. In
 some cases, personnel who will be responsible for the
 operation of the facilities are on the project team from
 its inception, as part of their training. In other cases,
 the operating team is assembled for training during
 the start-up and  shake-down procedures.  In any
 event,  careful training  of personnel before the
 contractor completes the  project appears to be an
 effective way to ensure  proper- operation of the
 facility over the long term.

 As  with most pollution  control projects, the
 effectiveness of the design is demonstrated by some
 type of performance testing. This  generally occurs
 after the equipment is operating "normally". For
 corrective action projects, certain facilities (such as
 organized above-ground treatment systems) may be
 able to  demonstrate effectiveness through  the
 performance testing mechanism. However, other
 systems (such  as groundwater pumping to
 control/recover a contaminant plume)  may require
 ongoing monitoring to  assess its effectiveness.
 Sampling and testing protocols  may have  to be
 developed and implemented to demonstrate  the
 performance of these systems.


 Summary
 The CMI requires close cooperation  between  the
 regulatory  community and  the  engineering  and
                                                 76

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 management team of the company performing the
 corrective action.  Through cooperation and  good
 planning, the Corrective Action Process can proceed
 in a timely fashion. Without such cooperation and
 planning, time and money can be misdirected and
 necessary protection of HHE can be delayed. Thus,
 from the start of the Corrective Action Process, it is
 important  to work  closely with the regulatory
 community in all phases of the project.
References

U.S. EPA.  1988a. RCRA Corrective Action Plan -
Interim Final EPA/530-SW-88-028, OSWER 9902.3,
Office  of Solid Waste and Emergency Response,
Washington, B.C., June 1988.
•U.S. Government Printing Office: 1992— 648-003/41850
                                               77

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