United States
Environmental Protection
Agency
Office of Emergency and Environmental
Remedial Response ... _ Response
Emergency Response Division Team
Treatment Technologies
for Superfund
Environmental Response
Training Program
-------
FOREWORD
This manual is for reference use of students enrolled in scheduled training courses of the U.S.
Environmental Protection Agency (EPA). While it will be useful to anyone who needs information
on the subjects covered, it will have its greatest value as an adjunct to classroom presentations
involving discussions among the students and the instructional staff.
This manual has been developed with a goal of providing the best available current information,
individual instructors may provide additional material to cover special aspects of their presentations.
Because of the limited availability of the manual, it should not be cited in bibliographies or other
publications.
References to products and manufacturers are for illustration only; they do not imply endorsement
by EPA.
Constructive suggestions for improvement of the content and format of the manual are welcome.
-------
TREATMENT TECHNOLOGIES FOR SUPERFUND
(165.3)
4 DAYS
This course instructs participants in the concepts and techniques for containment,
treatment, and disposal of hazardous materials associated with accidental releases and
uncontrolled waste sites. It emphasizes the practical applications of incident
mitigation and treatment technologies.
The objectives of the course are:
• To provide an overview of containment and treatment practices for mitigating
releases into air, surface water, soil, and groundwater
• To address environmental, financial, and regulatory considerations in the
application of treatment and disposal options
• To identify the logical progression of clean-up operations at uncontrolled
waste sites
• To describe principles of physical, biological, and chemical treatment and
present the practical application of field-tested treatment systems.
After completing the course, participants will be more knowledgeable about the
principles and applications of containment, handling, treatment, and disposal
technologies used at hazardous materials incidents.
111
-------
CONTENTS
Section 1
Section 2
Section 3
Section 4
Section 5
Section 6
Section 7
Section 8
Section 9
Section 10
Section 11
Section 12
Section 13
Section 14
Field Categorization
Chemical Characteristics
Waste Treatability
Groundwater Containment
Recovery Processes
Volatilization
Inorganic Treatment
Carbon Adsorption
Biological Treatment
Incineration
Soil Flushing and Washing
Immobilization
Disposal Options
Alternative Treatments
-------
Section 1
-------
FIELD CATEGORIZATION
STUDENT PERFORMANCE OBJECTIVES:
At the conclusion of this section, participants will be able to:
• Describe the advantages and disadvantages of field categorization and bulking
• Briefly describe the following site operations:
Site preparation
Drum handling
Drum sampling and labeling
Drum segregation and storage
• Describe basic field categorization analytical methods
• Briefly describe typical bulking procedures.
5/93
-------
NOTES
CHEMICAL INCOMPATIBILITY
The combination of two or more reactive
materials resulting in uncontrollable
and undesirable conditions.
PRACTICAL CONSIDERATIONS OF
CHEMICAL REACTIVITY
Heat Generation
Fire
Explosion
Formation of Toxic Vapors
Formation of Flammable Gases
Volatilization of Toxic or Flammable Substances
Formation of Substances of Greater Toxiclty
Formation of Shock-Sensitive Compounds
Pressurlzatlon In Closed Vessels
Solubility of Toxic Substances
Dispersion of Toxic Dust, Mists, and Particles
Violent Polymerization
COMPATIBILITY TESTING
CONSISTS OF
• Gross Identification of Wastes
• Segregation into Waste Categories
• Bench-Scale Compositing of
Compatible Materials
5/93
Field Categorization
page 1
-------
POSSIBLE REASONS FOR
COMPATIBILITY TESTING
• Gross Identification
• Segregation for Storage Purposes
• Determine Shipping Requirements
• Determine Disposal Method
• Economic
PROCESS DESCRIPTION
Site Preparation
Handling and Movement
Opening and Sampling
Labeling and Recording
Compatibility Testing
Segregation and Storage
Bulking
SITE PREPARATION
Field Categorization
page 2
5/93
-------
NOTES
HANDLING AND
MOVEMENT
OPENING
AND SAMPLING
LABELING AND
RECORDING
5/93
Field Categorization
page 3
-------
NOTES
COMPATIBILITY
TESTING
COMPATIBILITY TEST
SCHEMES
• Knowledge of Waste Materials at the Site
• Criteria Selected by the Oversight Agency
• Contractor's Experience and Preference
• Criteria of the TSD Facility
COMPATIBILITY TREE
1 Sample 1 (non-radioactive)
Strong Acid 4-fpH « 5,
,— ORP t— 0
1.O«TdU*r LOxIdlier
2. Reducing Agent
soluble
•*'" I U.....J
IpH
pH 5-9 pH > 9 1— » Strong B«M
1 (oh.ck CN-, 8.)
RP i LQBP
Z.Rtducmg Agent
add w
aier
V
1.O«ldlz*r
I.Rtduelng Agent
. Insoluble
no density density
gradients gradients
Water check Or
•olubto
floate
5% HCI
b»olubl«
L6% NlOH
Base
sinks
B*
po.1
IntoluU*
etelnTett
«M|MS<«<
nashjOlnt organic A?ld /Hal. Hydro.
. (cluck FP) S (eh«ck PCB)
Flammable Non-flammable
Hvdroc
iarbon
Hvdrocir
rtt
>on
Liquid Liquid '(chtcS FP) '(check FP)
Field Categorization
page 4
5/93
-------
NOTES
PH
• Potentially Dangerous Situations
- Toxic Gases
- Heat
- Uncontrolled Reaction Products
• pH Paper
• pH Meter
• Classification
OXIDIZERS AND REDUCERS
• Titanium Sulfate Indicator
- Colorimetrlc
- Yellow ; Organic Peroxides
- Brown ; Organic Oxidizers
- Problems with Complex Wastes
• Redox Potentiometer
- Simiiiar to pH Meter
- Uses mv Scale
- Problem Simiiiar to pH Meter
SCREENING FOR OXIDIZERS
AND REDUCERS
• Use Standard Test Solution that
Generates a known ORP
• Measure ORP Between a Sensing
Electrode and a Reference Electrode
• Add Unknown
• Remeasure ORP
5/93
Field Categorization
page 5
-------
NOTES
STANDARD TEST SOLUTIONS
• To Screen for Oxldlzers :
- 0.001 N Ferrous Ammonium Sulfate which
Generates 380mv; Positive if >430mv
• To Screen for Reducers :
- 0.001 N Potassium Chromate which
Generates 630mv; Positive If <580mv
WATER REACTIVITY
AND SOLUBILITY
• Normally One of the First Tests
• Characteristics when Mixed with Water
- Reacts Violently
- Forms Potentially Explosive Mixtures
- Generates Toxics, Vapors, or Fumes
• Small Volume of Waste Is Added to Water
- Reaction?
- Soluble?
- Floats/Sinks?
- Hexane Soluble?
ORGANICS AND HALOGENATED
ORGANICS
• PID at Drum Head
• Floaters — Organics
• Sinkers -- Halogenated Hydrocarbons
- Beilstein Test
- GC Scan
- PCB Check
Field Categorization
page 6
5/93
-------
NOTES
FLAMMABILITY
• Temperature at which the Vapors
of a Substance will Ignite
• Ignitability Test
- 0.1 gram or 0.1 ml Sample
Heat to Ignition
• Observations
- Flame jumps to Sample
- Flame touches Sample
— Heating Sample is required
FLAME TEST
Sample Composition
Aromatlo
Lower Aliphatic*
Oxygenated Compounds
Hctogenated Compounds
Aqueous Solutions
Polyhalogenated Compounds
General Behavior
- burn with smokey flame
• almost smokeless flame
- bluish flame
• smokey flame
• no Ignition - sizzle
- no Ignition - smokey
SEGREGATION AND
STORAGE
5/33
Field Categorization
page 7
-------
NOTES
BULKING
Field Categorization
page 8
5/93
-------
FIELD CATEGORIZATION
Drumming/Bulking Wastes
General Description
Stockpiled drums and small containers of potentially hazardous wastes can pose unique
problems in cleanup and disposal. Costs associated with analysis and repackaging of
numerous containers can be staggering.
Mixing compatible wastes and disposing of them in bulk quantities can effectively
reduce such costs. However, the volume of wastes or the number of containers directly
affects cost savings.
Repackaging usually involves placing original leaking containers into larger vessels,
sampling the contents, labeling the vessels for identification, and providing storage prior
to shipment or treatment. Bulking usually involves staging the containers,
recontainerizing leaking vessels, labeling the vessels for identification, sampling the
contents, conducting compatibility tests, performing bench scale compositing of
compatible materials, field bulking wastes, and storing or treating the wastes.
Applicable Wastes
Drummed or containerized wastes.
Process Description
It is important to collect as much information as possible about the stockpiled material before
attempting to move it. This information may assist in development of site safety and work
plans. General procedures applicable to drumming or bulking operations include:
• Site survey and staging layout
• Container handling
• Container opening and sampling
• Container labeling and data recording
• Compatibility testing (bulking operations)
• Bench compositing of compatibles (bulking operations)
• Container segregation and storage
• Bulking of compatibles (bulking operations).
5/93
-------
FIELD CATEGORIZATION
Each site is unique, so schemes for compatibility testing are site specific. However, each
site-specific scheme follows a flowchart similar to the one shown in FIGURE 1. The
scheme chosen for a specific action is based on the following factors:
• Knowledge of waste materials at the site
• Criteria selected by the oversight agency
• Contractor's experience and preference
• Criteria of the treatment, storage, and disposal (TSD) facility receiving the waste.
Drum Handling Operations
!
Locate and Excavate Drums
Locate and Separate.
Radioactive Drums
Stage for Sampling
!
Open and Sample
I
*Test for Compatibility
Incompatible | Compatible
I !
Isolate and Handle Stage for Bulking
Separately |
Bulk Wastes
!
Solidify or Treat
I
Transport and Dispose
FIGURE 1
FLOW DIAGRAM FOR DRUM HANDLING OPERATIONS
•"See FIGURE 2 for an example of a decision tree used for compatibility testing.
Note that incompatible wastes, including radioactive, water and air reactive, PCB, sulfide, and
cyanide wastes, are disposed of separately either in their original containers or overpacked.
5/93 10
-------
FIELD CATEGORIZATION
The site survey should include use of a gamma survey instrument to determine whether
containers emit gamma radiation above background levels (0.01 to 0.02 milliroentgen per
hour). If gamma radiation is above 1 milliroentgen per hour, a health physicist should be
contacted and the site safety and work plans should be amended as required. Containers
emitting gamma radiation above background levels should be considered potential sources of
radiation and are to be segregated from other materials.
All workers performing radioactive drum handling, sampling, or analysis should be
monitored by documented radiation dosimetry techniques.
A level area accessible to drum handling equipment such as backhoes or light duty cranes is
selected for staging. The contents of leaking containers should be transferred to sound
vessels before staging. Containers are then relocated to the staging area (normally through
the use of drum grapplers or slings) and are arranged in rows of two. This allows for
relatively easy access to any single container.
Remote methods should be used to open drums. This may be done by using a backhoe with
a brass or beryllium spike affixed to its bucket. Pneumatic devices are also available for
opening containers of various sizes.
Containers must be labeled either before or during sample collection. Labeling should be in
a sequential order so that containers may be located easily. Labels may be tags that are
wired to a container or they may be painted directly on the container. If tags are used they
must be weatherproof and should be affixed to the container with a heavy wire. If paint is
used it must not cover any original information about the ownership or contents of the
container.
Sampling of the container's head space with total vapor analyzers can reveal whether a
potentially explosive condition exists. Such an atmosphere exists when a direct-reading
instrument, such as a photoionization detector (PID), reads at 2000 units or more. Samples
that yield detector readings at such levels should be considered flammable until additional
material tests indicate otherwise. Instruments such as the PID and the organic vapor
analyzer-flame ionization detector (OVA-FID) have unique sensitivities and specificities to
identical substances, and the response of such instruments to "unknowns" may not yield
quantitative results. Furthermore, some dangerous substances such as phosgene, hydrogen
cyanide, and chlorine gas cannot be detected by PIDs or OVA-FIDs.
Samples of the container's contents are taken using drum thieves. Drum thieves are hollow
glass rods, approximately four feet long and lh inch in diameter. The rods are inserted into
the drum to their full length, the individual who is taking the sample places a finger over the
top of the rod and makes an airtight seal, the rod is withdrawn from the drum and inserted
into a sample container, the sampler's finger is withdrawn, and the sample flows from the
rod into the container. This is repeated until a sufficient sample volume is collected.
Because the drum contains a material that is assumed to be contaminated, the drum thief must
be left in the drum or must be decontaminated.
5/93 11
-------
FIELD CATEGORIZATION
As the sample is transferred from its original container, to the sample container it is visually
examined. Air reactive substances may ignite, emit fumes or gases, or release pressure.
Samples exhibiting these traits are considered to be air reactives, and containers holding such
substances must be separated from other containers. Furthermore, any drum found
containing solids submerged in liquid should be considered to contain an air or water reactive
substance. These drums must be separated from other containers.
Samples are delivered to a field laboratory for compatibility testing. The field laboratory is
often set up near the site. Field laboratories may be as complex as a mobile laboratory or
as simple as table space set up near the staging operations. The specific tests that will be
conducted to determine which wastes are compatible are selected based upon available site
information. FIGURE 2 shows a compatibility tree that has been used at a site to assist in
determining some waste characteristics. Flowcharts and compatibility trees are developed
for use at a specific site. However, many of the compatibility tests which are conducted on
waste samples are commonly used.
Stockpiled drums at hazardous waste sites pose special problems in cleanup and disposal.
Laboratory analysis, overpacking, and disposal on a drum-by-drum basis can be cost and
time prohibitive. Removing the wastes from drums, tanks, ponds, and lab packs and
combining compatible contents into larger volume containers is more economical and less
time consuming, especially for sites with more than 500 drums. However, wastes must first
be tested for compatibility before they are bulked and incompatible wastes must be
segregated.
Compatibility testing is neither as extensive nor as costly as standard laboratory
characterization procedures. A set of simple chemical tests like pH and water solubility is
performed following a flowchart scheme. These tests ultimately classify the material into
general categories. Enough information on the chemical characteristics can be generated to
develop a hazardous waste classification for shipping and disposal.
There is no standard compatibility testing scheme. The only requirements for establishing
a system are that analytical techniques and bulking protocols be effective, environmentally
sensitive, and safe. System selection factors include:
• Types of wastes suspected to be onsite as in the initial site survey
• Criteria chosen by the supervising government agency
• Contractor experience and preference
• Disposal facility criteria
• Treatment or recovery possibilities
5/93 12
-------
FIELD CATEGORIZATION
Compatibility testing is only part of the remedial project. Although each scheme is unique,
most follow a similar flowchart (the system shown in FIGURE 2 is used by O.H. Materials
Co.).
COMPATIBILITY TREE
1 Somple I (non-radioactive)
1
PH
I
•Slrono - pH«5 pH 5-9 pH»9 r _ t-t.»~p Base
Acid ^^ 1
1
ORP O
/ /
1. Oxidizer 1. Oxidizer
2. Reducing Agent
soluble
*wir|
|(ch
P ORP
X X
2. Reducing 1. Oxidizer
eck CN'.S1)
Agent 2. Reducing Agent
odd water
insoluble
floats sinks
Wale
|"| Reactive
j 5 V. HCI
no density
density gradients
soluble insoluble
k
gradients 1 . .
j J SXNoOH P°*"'
1 T sol. insol. ,
Water check Ba*»e 4 Halogen*
flash point Organic Acid Hydrocor
>^N. (check FP) Uneek pC
Flammable Non-flammable Hydrocarbon
Liquid Liquid (ch.ck FP)
Beilslein Test
neaolive
ft
aled
bon
B)
Hydrocarbon
(check FP)
SCREENS FOR: 1. Strong Acids 6. Water Rtodives
2. Strong Bases 7. Flammable Liquids
3. Oxldiieri 8. Halogenated Hydrocarbons
4. Reducing Agents $• PCB's
5. Cyanides & SullideJ
FIGURE 2
COMPATIBILITY TREE
5/93
13
-------
FIELD CATEGORIZATION
Tests Conducted Prior to Drum Opening:
Prior to drum opening, during the initial stages of evaluation radioactive wastes should be
identified. Using a gamma survey instrument as part of the air monitoring task, radioactivity
levels can be checked by scanning near the closed drums. (Low-level emitters may not cause
a response on the instrument. However, unless these sources are airborne they pose little
hazard.) Normal environmental background radiation level is 0.01 to 0.02 milliroentgen per
hour (mR/hr). Levels above 1 mR/hr is the maximum exposure limit without the advice of
a health physicist. It is recommended that the area be reanalyzed during compatibility
testing.
Tests Conducted at the Drumhead;
Following radioactive testing and separation of radioactive containers, the drums are staged
and opened for sampling. It is recommended that a remote method of drum handling and
opening such as a drum grappler and a backhoe equipped with a spike for piercing drums be
employed as a safety measure for workers. Drums must be staged for access to each, usually
in rows of two. Each drum must be labeled at the time of sample acquisition.
After opening, samples are taken of total vapor concentrations. A direct reading instrument
such as a photoionization or flame ionization detector may be used for this task. A
potentially explosive atmosphere may exist in the drum headspace denoted by a reading of
2000 ppm or 0.2% or greater on the instrument. Drums at or above 2000 ppm are classified
as flammable until more flammability data is available. (Limitations and operation
characteristics of the detection instrument must be taken into account. Proper calibration
when dealing with unknowns is impossible and also dangerous gases such as hydrogen
cyanide, phosgene, or chlorine are undetectable by PID or FID.)
The next test is for air reactivity. This test is performed by visual observation during
sampling. Any sample taken from a drum containing a solid that subsequently ignites,
fumes, gases, or releases pressure is considered air reactive and the drum is immediately
isolated. Separate any drum containing a metal packed in liquid. Additional sampling will
be necessary to determine the type of metal but extensive safeguards must be employed.
(Phosphorus, and sodium are examples of air and water reactive substances packed under
liquid for shipment.
Sample Acquisition;
Samples of 1 1 are common. If the drum contains several phases then a sample of each is
necessary along with an estimate as to the relative volume of each. The drum number and
the volume in the drum is noted, along with comments concerning drum type, condition, and
existing labeling. Results of drumhead tests are logged as are any special conditions. The
sample may be acquired using a drum thief or any device that is effective and will not
interfere with subsequent analysis. Laboratory clean glass jars are used as sample containers.
All appropriate safety and decontamination procedures are observed.
5/93 14
-------
FIELD CATEGORIZATION
Compatibility Tests on Collected Samples;
Water Reactivity/Solubility
This is one of the first tests performed and can yield a good deal of information on
the waste. (Sample size for testing is 1 ml for suspected reactives and 10 ml for
nonreactives.)
Characteristics of Reactivity
• Reacts violently with water
• Forms potentially explosive mixtures with water
• When mixed with water, generates toxic gases, vapors, or fumes in
a quantity sufficient to present a danger to human health or to the
environment.
A small volume of the material is added to water and the mixture is observed for
miscibility, temperature exotherm, precipitation, and gas formation. If any of these
occur, the substance is water reactive. (Following this definition, acids and bases are
considered reactive but will later be separated by a pH test.) When a liquid sample
is placed in water and is nonreactive, it will either be soluble or insoluble. If
insoluble, it will either sink or float. Samples that are soluble are often inorganic
substances. The solubility of these samples is then determined in hexane, and if it
is soluble in hexane, the substance is classified as a nonhalogenated organic. If
insoluble in hexane, the classification is inorganic liquid.
Organics and Halogenated Organics
Samples that are insoluble in water and float on water are classified as organic
liquids. The vapor concentration above the sample may be checked with a PID or
a FID to determine potential volatility (2000 ppm is classified as volatile organic).
Insoluble samples that sink in water are classified as halogenated organics. Further
tests to confirm halogen content using either a copper loop flame test, halogenated
organic GC scan, potentiometric titration, and total organic halogen (TOX) are
necessary. All drums classified as organics must be analyzed for PCBs to determine
disposal options. This test is conducted prior to bulking, usually at the bench
compositing stage. (It is recommended that no more than 10 drums at a time be
composited for sampling.) Any drums determined to contain >50 ppm PCBs are
classified as PCS contaminated.
5/93 15
-------
FIELD CATEGORIZATION
Flammability
Flammability is an arbitrary range of flash points chosen by EPA, DOT, and NFPA.
Flash point is the temperature at which the vapors of a substance will ignite as
determined through testing equipment such as the Setaflash, Pensky-Martins Flash
Point testers, and other approved testers.
For compatibility testing purposes the field test should be referred to as an
"ignitability" test. It has also been called pyrolysis testing, ignition testing, flame
tests, and other terms.
The ignition test procedure which is generally accepted is:
1. Place about 0.1 g (or 0.1 ml) of sample in a crucible cover
2. Bring the cover up to a flame
3. Heat gently until ignition takes place
4. If no ignition takes place, char the sample to observe combustibility
5. Ash and residue are used for other tests (e.g., metals content).
A few interesting extrapolations can be made from the ignition test. The first involves the
estimation of the flash point (flammability) of the sample, because the ease of ignition is
related to flammability. As the test sample is brought very slowly toward the flame, ignition
may take place before contact between the two—the flame seems to "jump" to the sample.
Such rapid ignition can be interpreted as a very low flash point (usually less than 100°F).
If the flame must contact the sample to ignite it, the flash point can be anywhere between
100°F and 200°F. If the sample must be heated before ignition, the flash point is usually well
over 200°F.
Another extrapolation relates the ignition test to the flame test. The behavior of the flame
is dependent on the composition of the sample. Some generalities may be made from this
test:
aromatic compounds burn with a smoky flame (sooty)
lower aliphatic compounds burn with an almost smokeless flame
compounds containing oxygen burn with a bluish flame
halogenated compounds burn with a smoky flame
aqueous solutions do not ignite but will sizzle when heated
polyhalogenated compounds in general, do not ignite but can momentarily
render the burner's flame smoky
5/93 16
-------
FIELD CATEGORIZATION
pH
Mixing acidic and caustic wastes can result in the evolutions of toxic gases i.e.
cyanide and sulfide. The pH measurements are taken to separate potentially
dangerous drums. (Cyanide and sulfide wastes are usually buffered at a pH >9 to
remain in aqueous solution.)
Water-soluble samples are tested using either a pH meter with temperature
compensation adjustment or indicator strips (pH paper). There are disadvantages to
both when used on samples containing organic layers or sludges. Meter probes are
easily fouled requiring frequent cleaning, recalibration, and replacement. Multiband
pH paper is recommended to limit interference caused by grease, sludges, opaque
solutions, and chemicals that can cause false color changes.
• Wastes with pH < 2 are classified as acids
• Wastes with pH between 2 and 7 are considered aqueous acidic solutions
• Wastes with pH between 7 and 12 are basic aqueous solutions
• Wastes with pH > 12 are classified as bases.
Samples with a pH greater than 10 are further tested by wet methods and ion selective
electrodes to determine the presence of cyanides or sulfides. Positive results require
that the drums be carefully separated to prevent accidental mixing during the bulking
process.
Acids and cyanide and sulfide-free bases may be mixed onsite for neutralization.
However, the reaction is exothermic so care must be taken in the bulking process to
limit volumes, monitor temperature, and monitor for cyanide and sulfide production.
Oxidizers and Reducers
Compatibility test procedures for classifying samples as oxidizers or reducers include
wet methods, test papers, and instrument methods.
Colorimetric methods can be used to identify oxidizers and reducers. For example,
titanium sulfate can be used as a yellow color indicator for organic peroxides in solid
unknowns, and manganous chloride can be used as a brown color indicator for
organic oxidizers. Various test papers are used, but may some not accurately identify
oxidizers and reducers in complex waste samples.
Potentiometric determination of redox potential using a portable instrument may also
be used. This method involves using an electrolyte of known potential and measuring
the change in this potential after the addition of a small portion of the waste sample.
5/93 17
-------
FIELD CATEGORIZATION
(Ferrous ammonium sulfate is used as the standard electrolyte solution for oxidizers
and potassium chromate for reduction measurement.)
Probes require frequent cleaning and recalibration as with the pH probe.
Caution is recommended in extrapolating inorganic test methods for use in organic
materials.
Labpacks
Small volume containers of laboratory wastes are frequently packed for disposal in
drums. Often the containers are unlabeled and incompatibles are packed together.
These labpacks pose some unique problems in characterization and disposal. After
the drum is opened, the contents are examined container by container. Similar items
are then repacked in sorbent materials for disposal. Unknowns are separated into
solids, liquids, and multiphase. Compatibility testing can be performed on each
container, the small containers can be disposed of using detonation, or they may be
crushed and solidified for land disposal.
Bench Compositing:
Compatible waste categories are composited in volume representative aliquots within each
category and then perhaps between similar categories. Care is taken to establish a safe
bulking order of mixing. Certain tests such as PCB tests may be conducted on composited
samples to guard against mixing wastes, which can cause disposal problems. It is
recommended that items be composited in groups of 10 prior to PCB testing to avoid
contaminating a very large composite.
Bulking;
The bulking process is done in a controlled chamber, usually 5000-gallon volume or less.
Air and temperature monitoring are a must. Bulking may be done by pumping directly from
the drums or containers or lagoons into a tanker, or by pouring drum contents into an open
container.
Liquids and sludges may be subsequently solidified for disposal. Empty drums are crushed.
(Empty = less than 1" heel or hardened substance in bottom of drum.)
Limitation of Compatibility Testing Procedures
Compatibility testing is a gross identification procedure used to place waste materials
in broad categories. Chemical reactions requiring heat, catalyzing effects, or long
reaction times are not detected. The identification of highly toxic substances, such
as some pesticides and carcinogenic materials, is beyond the scope of the test
methods. Major classes such as isocyanates, epoxides, nitriles, and polymerizable
materials cannot be determined.
5/93 18
-------
FIELD CATEGORIZATION
Representative samples of the drums themselves can be difficult to acquire and can
then affect the validity of test results.
The tests are by no means comprehensive, and increasing the complexity of the
scheme increases time and cost investments that can eventually render the system non-
cost-effective. Research continues to develop procedures that can better identify drum
contents, maintain rapid turnaround time for analysis, and be less costly than
laboratory procedures.
5/93 19
-------
Section 2
-------
CHEMICAL CHARACTERISTICS
STUDENT PERFORMANCE OBJECTIVES:
At the conclusion of this section, participants will be able to:
State the three criteria used to determine the chemicals shown in U.S. EPA
Priority Groups I and II
List at least three families of chemicals that are commonly found on
Superfund NPL sites
Define the terms molecular weight, specific gravity, solubility, vapor
pressure, Henry's Law Constant, organic carbon partition coefficient
octanol/water partition coefficient (Kow), and biodegradability
List at least one treatment technology affected by each of the following:
Molecular weight
Specific gravity
Solubility
Vapor pressure
Henry's Law Constant
Organic carbon partition coefficient (K^)
Octanol/water partition coefficient (Kow)
Biodegradability.
5/93
-------
NOTES
Priority List Substances
1 Lead 7 pQgs
2 Arsenic a Chloroform
3 Mercury 9 Benzo(b)fluoranthene
4 Vinyl Chloride lOTrichloroethylene
5 Benzene 11 Chlordane
6 Cadmium 12 Benzo(a)pyrene
Priority List Substances
Chemical Toxicity
Frequency of Occurrence
Potential for Human Exposure
Priority List Substances
Pol/cyclic Aromatic
Hydrocarbons
B«nzo(b)fluoranthene (9)
B«nzo(a)pyrene (12)
Chrysene (95)
Chlorinated Organic
Compounds
Vinyl Chloride (4)
PCBs (5)
Trlchloroethylene (10)
Inorganics
Metals Non-metals
Lead (1) Cyanide (25)
Arsenic (2) Ammonia (141)
Chromium (19) Chlorine (192)
5/93
Chemical Characteristics
page 1
-------
NOTES
Priority List Substances
Amines
N-Nitrosodi-N-Propylamine (83)
N-Nitrosodiphenylamine (186)
N-nitrosodimethylamine (195)
Phthalates
Aromatic Ring
Compounds
Benzene (5)
Ethyl Benzene (66)
Styrene (266)
Di-N-Butyl Phthalale (28)
Di-(2-Ethylhexyl)Phthalate (56)
Butyl Benzyl Phthalale (133)
WASTE CHARACTERISTICS
• Molecular Weight, g/mole
• Specific Gravity, ratio
• Solubility (water), mg/L
• Vapor Pressure, mmHg
• Henry's Law Constant, atm-m 3/mol
• K , ml/g
oc "
• K , ratio
ow
• Biodegradability, subjective
MOLECULAR WEIGHT
The mass of a specific number of molecules
for a known compound.
-Mobility:
High Mol. Wt. vs Low Mol. Wt.
Chemical Characteristics
page 2
5/93
-------
NOTES
SPECIFIC GRAVITY
• The weight of a given volume of substance
compared to the weight of water at 4°C.
• Specific gravity can be used to predict
whether compounds are likely to float or
sink.
SPECIFIC GRAVITY
OF SEVERAL COMPOUNDS
COMPOUND
Phenol
PCBs
TCE
Chrysene
Vinyl Chloride
SPECIFIC GRAVITY
1.07
1.4-1.5
1.46
1.274
0.912
SOLUBILITY
• The maximum concentration of a chemical that
dissolves in pure water at a given temperature.
• Highly soluble
Aqueous contamination
• Insoluble
Pure product recovery
• Factors that influence solubility
Polarity
Temperature
PH
5/93
Chemical Characteristics
page 3
-------
NOTES
VAPOR PRESSURE
• The pressure exerted at a given temperature
when a solid or liquid is in equilibrium with its
own vapor.
• Inversely proportional to boiling point.
• Directly proportional to temperature.
VAPOR PRESSURE OF WATER
VARIATION WITH TEMPERATURE
DEGREES C
5
10
20
50
100
mmHg
6.54
9.21
17.5
92.5
760
HENRY'S LAW CONSTANT
Expression which relates the concentration of a
chemical dissolved in the aqueous phase
to the concentration of the chemical in the
gaseous phase when the two are in equilibrium.
VP/S
VP - Vapor Pressure, atm
S - Solubility, mol/m"
Chemical Characteristics
page 4
5/93
-------
/VOTES
ORGANIC CARBON /lx .
PARTITION COEFFICIENT (Koc )
• Indicates the tendency of a chemical to be
adsorbed.
• Ranges 1 to 10,000,000
The higher the value, the greater the sorption.
• Koc influenced by:
Temperature
Grease and oils
Solids
ORGANIC CARBON
PARTITION COEFFICIENT (Koc)
'.oc'
mg compound adsorbed / Kg organic carbon
mg dissolved / liter solution
(Koc) VALUES
Chemical Name «,„
PCBs 53,000
DCM 8.8
Benzene 83
Toluene 300
TCE 126
Tetrachloroethylene 364
Vinyl Chloride 57
Benzo(b)pyrene 550,000
5/93
Chemical Characteristics
page 5
-------
NOTES
OCTANOL/WATER
PARTITION COEFFICIENT
Relates the partitioning of a specific
compound between non-polar and polar
phases.
[X] OCTANOL
ow
[X] WATER
K^VALUES
Chemical Name KgW
PCBs 6.04
DCM 1.30
Benzene 2.13
Toluene 2.73
TCE 2.38
Tetrachloroethylene 2.60
Vinyl Chloride 1.38
Benzo(b)pyrene 6.06
BIODEGRADABILITY
• The susceptibility of a substance to
decompose by microorganisms.
• Subjective
Degradable
Non-Degradable
Refractory
Chemical Characteristics
page 6
5/93
-------
NOTES
BIODEGRADABILITY
• The susceptibility of a substance to
decompose by microorganisms.
• Subjective
Degradable
Non-Degradable
Refractory
5/93
Chemical Characteristics
page 7
-------
CHEMICAL CHARACTERISTICS
INTRODUCTION
Usually, several different types of hazardous chemicals are found on a CERCLA (Superfund) site,
and the chemicals differ from site to site. CERCLA stands for the Comprehensive Environmental
Response, Compensation and Liability Act.
Different types of hazardous chemicals have different physical and chemical characteristics and
require different treatment technologies. The characteristics determine the proper treatment
technology for each type of chemical.
Because several types of chemicals are present on most Superfund sites, more than one treatment
technology is usually needed at the site. When two or more treatment technologies are used together
to clean up a site, the combination is typically referred to as a treatment train.
SUPERFUND SITE CHEMICALS
Priority List I and II Chemicals
In 1987 and 1988, two lists were prepared of hazardous chemicals found on the Superfund
National Priority List (NPL) sites. These lists are the Hazardous Substances Priority Lists.
They are commonly called Priority List I and Priority List II. Each list contains 100
chemicals.
The lists were required by CERCLA Section 104, as amended by the Superfund Amendments
and Reauthorization Act (SARA). They were prepared by the U.S. EPA and the Agency for
Toxic Substances and Disease Registry (ATSDR), which is part of the U.S. Department of
Health and Human Services. The lists were to be in order of priority based on the following
criteria:
• Chemical toxicity - determined using the reportable quantity scoring scheme.
• Frequency of occurrence - obtained from data listed by the Contract Laboratory
Program (CLP).
• Potential for human exposure - determined from several sources including CLP
data, and selection of the chemical for detailed exposure and risk assessment at
Superfund sites.
5/93
-------
CHEMICAL CHARACTERISTICS
The first list was published April 17, 1987, and the second list was published October 20,
1988. They are found in 52 FR 12866, April 17, 1987, and 53 FR 41279, October 20,
1988, respectively.
List of 25
The list of 25, FIGURE 1, is a list of the 25 chemicals most often identified on Superfund
sites. It was developed by McCoy and Associates (an independent contractor). Because
these chemicals are commonly found on Superfund sites, there is a good chance you'll find
them (or similar chemicals) on your site.
25 MOST IDENTIFIED CHEMICALS
ON SUPERFUND SITES
TRICHLOROETHYLENE
LEAD AND COMPOUNDS
TOLUENE
BENZENE
PCBs
CHLOROFORM
TETRACHLOROETHYLENE
PHENOL
ARSENIC AND COMPOUNDS
CADMIUM AND COMPOUNDS
CHROMIUM AND COMPOUNDS
1,1,1 -TRICHLOROETH ANE
ZINC
ETHYLBENZENE
XYLENE o,m,p
METHYLENE CHLORIDE
TRANS-1,2-DICHLOROETHYLENE
MERCURY
COPPER AND COMPOUNDS
CYANIDES
VINYL CHLORIDE
1,2-DICHLOROETHANE
CHLOROBENZENE
1,1 -DICHLOROETH ANE
CARBON TETRACHLORIDE
FIGURE 1
LIST OF 25
Types of Commonly Found Chemicals
• Polycyclic aromatic hydrocarbons - organic compounds containing three or more
ring structures. Examples of polycyclic aromatic hydrocarbons are chrysene,
anthracene, and benzo(a)pyrene. Many of these chemicals are known or suspected
carcinogens.
5/93
10
-------
CHEMICAL CHARACTERISTICS
Chlorinated organic compounds - organic compounds containing chlorine.
Examples of chlorinated organic compounds are polychloro-biphenols (PCBs) and
trichloroethylene (TCE). These types of chemicals are frequently toxic, some are
skin absorbable, and many are known or suspected carcinogens.
Inorganics - include both metals and non-metals. Chromium (VI), lead and mercury
are examples of hazardous metals. These chemicals are toxic, and some (chromium
(VI)) are water soluble.
Cyanide is an example of a hazardous inorganic non-metal. Cyanide is poisonous,
skin absorbable and, in combination with acids, forms a poisonous gas.
Amines - organic chemicals that contain nitrogen compounds as NH groups
(generally derived from ammonia). An example of a commonly found amine is N-
nitrosodiphenylamine. Some amines are toxic, some are suspected carcinogens, and
at high concentrations, some are explosive.
Aromatic ring compounds - organic compounds arranged in ring structures. One
very commonly found example of an aromatic ring compound is benzene. Benzene
is toxic and it is a known carcinogen.
Phthalates - compounds formed by combining organic acids (acids combine at the
COOH groups with the removal of a water molecule). One example is Di(2-
ethylhexyl) phthalate. Phthalates are irritants and some are suspected teratogens.
HAZARDOUS CHEMICAL CHARACTERISTICS
A number of different physical and chemical characteristics affect the type of treatment technologies
chosen to clean up a Superfund site. They include molecular weight, specific gravity, solubility,
vapor pressure, Henry's Law Constant, organic carbon partition coefficient (K^), octanol/water
partition coefficient (Kow), and biodegradability.
Molecular Weight
This is the weight of one mole of a chemical. One mole equals 6.02 x 1023 atoms or
molecules. Molecular weight is measured in grams per mole. It is the total weight of all
atoms or ions that are part of a molecule. For example, the molecular weight for sodium
chloride (NaCl or table salt) is calculated as follows:
Na = 23 grams/mole
Cl = 35.5 grams/mole
NaCl = 58.5 grams/mole
5/93 11
-------
CHEMICAL CHARACTERISTICS
The larger the molecule, the higher the molecular weight.
Molecular weight affects mobility. Generally the higher the molecular weight, the less
mobile the chemical. Less mobile chemicals are frequently good candidates for
immobilization techniques. More mobile (lower molecular weight) chemicals may be more
easily removed using air stripping, vacuum extraction, or similar techniques.
Specific Gravity
The weight of a given volume of a chemical compared to the weight of an equal volume of
water at 4 degrees Celsius (4°C). The unit of measure for specific gravity is determined as
follows:
1.0 = water
> 1.0 is heavier than water (sinks)
< 1.0 is lighter than water (floats)
Specific gravity indicates whether a chemical will float or sink when mixed with water.
Insoluble floaters are generally easier to remove with pure product recovery methods such
as skimming. Insoluble sinkers typically require more extensive treatment technologies such
as dredging or soil removal followed by immobilization or incineration.
Solubility
The maximum amount (concentration) of a chemical that will dissolve in pure water at a
given temperature (usually 4°C). Solubility is usually measured in grams/liter for highly
soluble chemicals, or in milligrams/liter (parts per million - ppm) for low solubility
chemicals.
A low solubility chemical will either float or sink on water, it won't mix with it. This may
allow pure product recovery, immobilization, or incineration. A more soluble chemical may
mix with water and then require aqueous cleanup techniques such as air stripping or carbon
adsorption.
NOTE: some chemicals are so toxic that even though they have low solubilities (measured
in pans per million) aqueous cleanups are still needed.
Vapor Pressure
The pressure exerted at a given temperature when a solid or liquid is in equilibrium with its
own vapor. Basically this is the pressure exerted by the vapor that's coming off a solid or
liquid. Vapor pressure is measured in millimeters of mercury (mm Hg) or in atmospheres
(760 mm hg = 1 atmosphere).
5/93 12
-------
CHEMICAL CHARACTERISTICS
Vapor pressure is a measure of the relative volatility of a chemical. Generally the more
volatile a chemical, the better for air stripping or vacuum extraction. However, other factors
[i.e., solubility, soil structure, etc.] also affect these techniques. Lower vapor pressure
chemicals are usually treated using carbon, adsorption, soil washing, immobilization,
incineration, or some similar technology.
Henry's Law Constant
This is an expression which relates to the concentration of a chemical dissolved in an
aqueous phase to the concentration (or pressure) of the chemical in the gaseous phase when
the two are in equilibrium. Basically, it is a measure of the volatility of a chemical when
it's dissolved in water. A high Henry's Law Constant value indicates a chemical with an
affinity for air rather than water.
Henry's Law Constant can be measured in Atm per meterVmole, but this varies. For
instance it is often shown dimensionless. It is one of the primary measurements used in
determining the effectiveness of air stripping (high Henry's Law Constants indicate good
candidates for air stripping).
Organic Carbon Partition Coefficient (KOT)
This is a value which indicates the tendency of a chemical to be adsorbed on organic carbon.
K^ is usually shown as ml/gm of carbon.
I^ is one of the primary measurements used in determining the effectiveness of carbon
adsorption. A chemical with a high K^ is probably a good candidate for carbon adsorption.
Octanol/Water Partition Coefficient (K.,.)
Basically this is a value which relates the partitioning of a chemical between non-polar
(hydrocarbon) and polar (aqueous) phases. However, it can also include a lipid or fatty acid
phase. A K,,w is measured as a dimensionless ratio ranging from less than one to greater than
10,000. Due to a wide range of measurements, Kows are often shown as logarithmic values.
Kow measurements help determine the feasibility of chemical removal/recovery using solvent
extraction or soil washing techniques. These technologies are generally more efficient when
used to treat chemicals with a relatively high Kow.
Biodegradabilitv
The susceptibility of a chemical to be decomposed by micro-organisms. Biodegradability is
a unitless measurement. Chemicals are usually listed as degradable, non-degradable, or
refractory. The term refractory has several definitions, the most commonly used one seems
to be partially degradable. Biodegradability is the key component in determining the
feasibility of biological treatment techniques.
5/93 13
-------
CHEMICAL CHARACTERISTICS
CONCLUSION
A number of different hazardous chemicals are usually found on Superfund sites. One of the keys
to a successful, cost-effective cleanup is using the chemicals' characteristics to help choose the
correct treatment technologies.
5/93 14
-------
Section 3
-------
WASTE TREATABILITY
STUDENT PERFORMANCE OBJECTIVES:
At the conclusion of this unit, participants will be able to:
• Briefly describe the advantages of treatability studies as part of the remedial
investigation and feasibility study process
• Briefly describe technology screening
• Briefly describe the differences between the following types of treatability
studies:
Laboratory scale
Bench scale
Pilot scale
• List at least four sources of information for treatability studies.
5/93
-------
NOTES
TREATABILITY STUDIES
Definition:
Research conducted on a specific
waste to determine whether
a treatment, or combination of
treatments, will effectively reduce
the hazardous nature of the waste
WHY CONDUCT A TREATABILITY STUDY
• Statutory mandate, CERCLA 121 (b)
Permanent solutions
Alternative treatments
Resource recovery
• Reduce volume, toxicity, or mobility
• Maximum extent practicable (MEP)
TIMING OF TREATABILITY STUDIES
• Information gathered at listing
Technology prescreening
• Concurrent with RI/FS
Remedy screening (Tier 1)
Remedy selection (Tier 2)
• Post ROD (Record of Decision)
RD/RA (remedial design/
remedial action) (Tier 3)
5/93
Waste Treatability
page 1
-------
NOTES
Waste Treatability
page 2
The Role
Scoping ^
~f»RI/Fg~?
Tochnologx
Praacraanin(
and
Traatabllfty
Study
Scoping
of Treats
Hunt
ft
Sill
_Ch«r«c1«rt
"and Tachfl
Beroan
ibility S
Hal Invaal
aalMHty S
Mantifi
of Altar
mlon
oloey"*
ng
Itudies in the RI/FS and RD/RA Process
»g«ion/ B.cord Htm.di.l D.tian/ -J
tudy ^bt B«
Mtion "•"
n«bv» 8*<«
Evaluation •>
of *H»m«Ov»» "^
REMEDY SCREENING
TREATABILITY
to datarmin*
potential faaalbiUty
REMEDY SELECTION
TREATABILITY
to 4«v«lDp p«r1orm«ic«
•nd con d«<
a«on B.m.di«l Action ^
Didy
-tion
Implamintation ^
of n«m«dy
RD/RA TREATABILITY
to d«v«lop datallid diilgn
•nd co«t data and to
GOnRrm parformanc*
TECHNOLOGY PRESCREENING
• Literature/databases search
• Data needs/data quality objectives
• Treatability study sources/contractors
• Work assignment/plan
LITERATURE SEARCH
• Training courses and conferences
• Vendors and contractors
• Publications and bulletin boards
• Databases
5/93
-------
NOTES
DATA NEEDS/OBJECTIVES
• Existing site information
• Data quality objectives (DQOs)
• Adequate site data
• Information needed for technology evaluation
Total organic carbon (TOG)
PH
Clay content
Withdrawal rate
Other
TREATABILITY STUDY SOURCES
• Vendors
• Consultants
• Federal agencies
TREATABILITY STUDY FLOWCHART
Determine
Data Needs
Evaluate Existing
Site Data
YES
Data Adequate to
Screen or Evaluate
Alternatives?
NO
Treatability
Study
Detailed Evaluation
5/93
Waste Treatability
page 3
-------
NOTES
REMEDY SCREENING (TIER1)
• Potential feasibility
• Performance goals
• Additional data needs
REMEDY SCREENING (TIER1)
• Laboratory/bench scale
• Small quantities, quick results
• Batch reactions, yes/no answers
• Hours to days
• $10,000 to $50,000
REMEDY SELECTION (TIER 2)
• Performance and cost data
• Verify cleanup criteria
Waste Treatability
page 4
5/93
-------
NOTES
REMEDY SELECTION (TIER 2)
• Bench/pilot scale
• Batch or continuous processes
• Days to weeks
• $50,000 to $250,000
REMEDIAL DESIGN/ACTION (TIER 3)
• Detailed design
• Cost and performance data
REMEDIAL DESIGN/ACTION (TIER 3)
• Pilot/full scale
• Batch or continuous reactions
• Weeks to months
• $250,000 to $1,000,000
5/33
Waste Treatability
page 5
-------
NOTES
RCRA EXCLUSION RULE
TREATABILITY STUDIES
• Exempts waste samples from permit
requirements
One-time exclusion of
1,000 kg/wastestream per
treatment process
• Only effective in non-RCRA-authorized
states
Waste Treatability
page 6
5/93
-------
TREATABILITY REFERENCES
USEPA. 1987. U.S. Environmental Protection Agency, Data quality objectives for remedial
response activities: Development process. EPA-540/G-87/003. OSWER Directive No.
9355.0-7b. OERR-OSWER Washington, D.C.
USEPA. 1988. U.S. Environmental Protection Agency, Technology screening guide for treatment
of CERCLA soils and sludges. EPA-540/2-88/004. OERR-OSWER, Washington, D.C.
USEPA. 1990. U.S. Environmental Protection Agency, Technical support services for Superfund
site remediation. EPA-540/8-90/001. OERR-OSWER, Washington, D.C.
USEPA. 1990. U.S. Environmental Protection Agency, Engineering Bulletin - Chemical
dehalogenation treatment: APEG treatment. EPA-540/2-90/015. RREL-ORD, Cincinnati,
OH; OERR-OSWER, Washington, D.C.
USEPA. 1991. U.S. Environmental Protection Agency, Accessing federal data bases for
contaminated site clean-up technologies. EPA-540/8-91/008. Member Agencies of the
Federal Remediation Technologies Roundtable, Washington, D.C.
USEPA. 1991. U.S. Environmental Protection Agency, Bibliography of federal reports and
publications describing alternative and innovative treatment technologies for corrective action
and site remediation. EPA-540/8-91/007. Member Agencies of the Federal Remediation
Technologies Roundtable, Washington, D.C.
USEPA. 1991. U.S. Environmental Protection Agency, Engineering Bulletin - Thermal desorption
treatment. EPA-540/2-91/008. RREL-ORD Cincinnati, OH; OERR-OSWER, Washington,
D.C.
USEPA. 1991. U.S. Environmental Protection Agency, Engineering Bulletin - In situ soil vapor
extraction treatment. EPA-540/2-91/006. RREL-ORD, Cincinnati, OH; OERR-OSWER,
Washington, D.C.
USEPA. 1991. U.S. Environmental Protection Agency, Engineering Bulletin - In situ soil flushing.
EPA-540/2-91/021. RREL-ORD, Cincinnati, OH; OERR-OSWER, Washington, D.C.
USEPA. 1991. U.S. Environmental Protection Agency, Engineering Bulletin - Chemical oxidation
treatment. EPA-540/2-91/025. RREL-ORD, Cincinnati, OH; OERR-OSWER, Washington,
D.C.
USEPA. 1991. U.S. Environmental Protection Agency, Engineering Bulletin - Air stripping of
aqueous solutions. EPA-540/2-91/022. RREL-ORD, Cincinnati, OH; OERR-OSWER,
Washington, D.C.
USEPA. 1991. U.S. Environmental Protection Agency, Engineering Bulletin - Air stripping of
aqueous solutions. EPA-540/2-91/022. RREL-ORD, Cincinnati, OH; OERR-OSWER,
Washington, D.C.
5/93
-------
TREATABILITY REFERENCES
USEPA. 1991. U.S. Environmental Protection Agency, Superfund Engineering Issue - Treatment
of lead-contaminated soils. EPA-540/2-91/009. RREL-ORD, Cincinnati, OH; OERR-
OSWER, Washington, D.C.
USEPA. 1991. U.S. Environmental Protection Agency, Engineering Bulletin - Control of air
emissions from materials handling during remediation. EPA-540/2-91/023. RREL-ORD,
Cincinnati, OH; OERR-OSWER, Washington, D.C.
USEPA. 1992. U.S. Environmental Protection Agency, Guide for conducting treatability studies
under CERCLA. EPA-540/R-92/071a. OSWER Directive No. 9380.3-10. RREL-ORD,
Cincinnati, OH; OERR-OSWER, Washington, D.C.
USEPA. 1992. U.S. Environmental Protection Agency, Guide for conducting treatability studies
under CERCLA: soil washing. EPA-540/2-9l/020a. OERR-OSWER, Washington, D.C.
USEPA. 1992. U.S. Environmental Protection Agency, Guide for conducting treatability studies
under CERCLA: chemical dehalogenation. EPA-540/R-92/013a. OERR-OSWER,
Washington, D.C.
USEPA. 1992. U.S. Environmental Protection Agency, Guide for conducting treatability studies
under CERCLA: solvent extraction. EPA-540/R-92/016a. OERR-OSWER, Washington,
D.C.
USEPA. 1992. U.S. Environmental Protection Agency, Guide for conducting treatability studies
under CERCLA: aerobic biodegradation screening. EPA-540/2-91/013a. OERR-OSWER,
Washington, D.C.
USEPA. 1992. U.S. Environmental Protection Agency, Guide for conducting treatability studies
under CERCLA: soil vapor extraction. EPA-540/2-92/019a. OERR-OSWER, Washington,
D.C.
USEPA. 1992. U.S. Environmental Protection Agency, Engineering Bulletin - Technology
preselection data requirements. EPA-540/S-92/009. RREL-ORD, Cincinnati, OH; OERR-
OSWER, Washington, D.C.
USEPA. 1992. U.S. Environmental Protection Agency, Engineering Bulletin - Air pathway
analysis. EPA-540/S-92/013. RREL-ORD, Cincinnati, OH; OERR-OSWER, Washington,
D.C.
USEPA. 1992. U.S. Environmental Protection Agency, Engineering Bulletin - Supercritical water
oxidation. EPA-540/S-92/006. RREL-ORD, Cincinnati, OH; OERR-OSWER, Washington,
D.C.
USEPA. 1992. U.S. Environmental Protection Agency, Engineering Bulletin - Slurry walls.
EPA-540/S-92/006. RREL-ORD, Cincinnati, OH; OERR-OSWER, Washington, D.C.
5/93
-------
TREATABILITY REFERENCES
USEPA. 1992. U.S. Environmental Protection Agency, Engineering Bulletin - Pyrolysis treatment.
EPA-540/S-92/010. RREL-ORD, Cincinnati, OH; OERR-OSWER, Washington, D.C.
USEPA. 1992. U.S. Environmental Protection Agency, Engineering Bulletin - Rotating biological
contactors. EPA-540/S-92/010. RREL-ORD, Cincinnati, OH; OERR-OSWER, Washington,
D.C.
USEPA. 1992. U.S. Environmental Protection Agency, Engineering Bulletin - Selection of control
technologies for remediation of lead battery recycling sites. EPA-540/S-92/011. RREL-
ORD, Cincinnati, OH; OERR-OSWER, Washington, D.C.
USEPA. 1992. U.S. Environmental Protection Agency, Engineering Bulletin - Design
considerations for ambient air monitoring at Superfund sites. EPA-540/S-92/012. RREL-
ORD, Cincinnati, OH; OERR-OSWER, Washington, D.C.
USEPA. 1992. U.S. Environmental Protection Agency, Superfund Engineering Issue -
Considerations for evaluating the impact of metals partitioning during the incineration of
contaminated soils from Superfund sites. EPA-540/S-92/014. RREL-ORD, Cincinnati, OH;
OERR-OSWER, Washington, D.C.
USEPA. 1992. U.S. Environmental Protection Agency, Guide for conducting treatability studies
under CERCLA: thermal desorption. EPA-540/R-92/074B. OERR-OSWER, Washington,
D.C.
USEPA. 1993. U.S. Environmental Protection Agency, Engineering Bulletin - Landfill covers.
EPA-540/S-93/500. RREL-ORD, Cincinnati, OH; OERR-OSWER, Washington, D.C.
5/93
-------
TREATABILITY DATABASES
Database
RREL Treatability Database
ATTIC
COLIS
VISITT
Super fund TSP
Engineering TSC
ERT-TSC
Contact
Glenn Shaul
RREL-ORD
USEPA
(513) 569-7408
Greg Ondich
OEETD
USEPA
(202) 260-5747
Robert Hillger
RREL-ORD
USEPA
(908) 321-6639
VISITT Hotline
(800) 245-4505
Marlene Suit
TIO-OSWER
USEPA
(703) 308-8800
Ben Blaney or Joan Colson
RREL-ORD
(513) 569-7406
Joseph LaFornara
ERB-OERR
USEPA
(908) 321-6740
5/93
10
-------
United States
Environmental Protection
Agency
Office of
Solid Waste and
Emergency Response
Directive 9380.3-02FS
December 1989
&EPA
TREATABILITY STUDIES UNDER
CERCLA: AN OVERVIEW
Office of Emergency and Remedial Response
Hazardous Site Control Division OS-220
Quick Reference Fact Sheet
Section 121(b) of CERCLA mandates EPA to select remedies that "utilize permanent solutions and
alternative treatment technologies or resource recovery technologies to the maximum extent practicable" and to
prefer remedial actions in which treatment "permanently and significantly reduces the volume, toxicity, or mobility
of hazardous substances, pollutants, and contaminants as a principal element." Treatability studies provide data to
support treatment technology selection and remedy implementation and'should be performed as soon as it is evident
that insufficient information is available to ensure the quality of the decision. Regional planning should factor in the
time and resources required for these studies.
This fact sheet provides a synopsis of information to facilitate the planning and execution of treatability
studies in support of the RI/FS and the RD/RA processes. Detailed information on designing and implementing
treatability studies for the RI/FS process is provided in the "Guide for Conducting Treatability Studies under
CERCLA," Interim Final, EPA 540/2-89/058, December 1989. A summary of Chapter 2 (Overview of Treatability
Studies) is incorporated in this paper. The remainder of that document provides protocols for implementing the
studies.
DEFINING TREATABILITY STUDIES
Treatability studies are laboratory or field tests de-
signed to provide critical data needed to evaluate and, ul-
timately, to implement one or more treatment technolo-
gies. These studies generally involve characterizing un-
treated waste and evaluating the performance of the tech-
nology under different operating conditions. These re-
sults may be qualitative or quantitative, depending on the
level of treatability testing. Factors that influence the
type or level of testing needed include: phase of the
project [e.g., remedial investigation/feasibility study (RI/
FS) or remedial design/remedial action (RD/RA)], tech-
nology-specific factors, and site-specific factors.
• Treatability studies conducted during the RI/FS
to support remedy selection are generally used
to determine whether the technology can achieve
the anticipated Record of Decision (ROD) goals
and to provide information to support the nine
evaluation criteria to the extent possible.
Treatability studies to support remedy implem-
entation during RD are generally used to verify
that the technology can achieve the ROD goals,
optimize design and operating conditions nec-
essary to ensure performance, and improve cost
estimates.
LEVEL OF TREATABILITY STUDIES
Treatability studies should be performed in a sys-
tematic fashion to ensure that the data generated can
support the remedy evaluation and implementation proc-
ess. A well-designed treatability study can significantly
reduce the overall uncertainty associated with the deci-
sion, but cannot guarantee that the chosen alternative
will be completely successful. Care must be exercised
to ensure that the treatability study is representative of
the treatment as it will be employed (e.g., sample is rep-
resentative of waste to be treated) to minimize the
uncertainty in the decision. The method presented be-
low provides a resource-effective means for evaluating
one or more technologies.
-------
There are three levels or tiers of treatability studies:
laboratory screening, bench-scale testing, and pilot-scale
testing. Some or all of the levels may be needed on a
case-by-case basis. The need for and the level of treata-
bility testing required are management decisions in
which the time and cost necessary to perform the testing
are balanced against the risks inherent in the decision
(e.g., selection of a treatment alternative). These deci-
sions are based on the quantity and quality of data
available and on other decision factors (e.g., State and
Community acceptance of the remedy, new site data).
The flow diagram for the tiered approach in Figure 1
traces the stepwise review of study data and the decision
points and factors to be cqnsidered.
• Laboratory screening is the first level of test-
ing. It is used to establish the validity of a tech-
nology to treat a waste. These studies are
generally low cost (e.g., $ 1OK-50K) and usually
require hours to days to complete. They yield
data that can be used as indicators of a technol-
ogy's potential to meet performance goals and
can identify operating standards for investiga-
tion during bench- or pilot-scale testing. They
generate little, if any, design or cost data and
generally are not used as the sole basis for selec-
tion of a remedy.
Bench-scale testing is the second level of test-
ing. It is used to identify the technology's per-
formance on a waste-specific basis for an oper-
able unit. These studies generally are of moder-
ate cost (e.g., $50K-250K) and may require
days to weeks to complete. They yield data that
verify that the technology can meet expected
cleanup goals and can provide information in
support of the detailed analysis of the alterna-
tive (i.e., the nine evaluation criteria).
Pilot-scale testing is the third level of testing. It
is used to provide quantitative performance,
cost, and design information for remediating an
operable unit. This level of testing also can
produce data required to optimize performance.
These studies are of moderate to high cost (e.g.,
$250K-1,OOOK) and may require weeks to
months to complete. They yield data that verify
Figure 1. Flow Diagram of the Tiered Approach
MANAGEMENT DECISION FACTORS: |
• SUI« «nd Community AcwpOne*
• Sditdul* Coi««ru
• AMilontl 0«U
-------
performance to a higher degree than the bench-
scale and provide detailed design information.
Theyaremostoftenperformedduringthe remedy
implementation phase of a site cleanup, although
this level may be appropriate to support the
remedy evaluation of innovative technologies.
Technologies generally are evaluated first at the labora-
tory screening level and progress through the bench-
scale to the pilot-scale testing level. A technology may
enter, however, at whatever level is appropriate based on
available data on the technology and site-specific fac-
tors. For example, a technology that has been studied ex-
tensively may not warrant laboratory screening to deter-
mine whether it has the potential to work. Rather, it may
go directly to bench-scale testing to verify that perform-
ance standards can be met.
DETERMINING THE NEED FOR
TREATABILITY STUDIES
Treatability studies for remedy evaluation and im-
plementation represent good engineering practice. The
determination of the need for and the appropriate level of
Figure 2. Decision Tree Showing When Treatability
Studies Are Needed to Support the Evaluation and
Selection of an Alternative
DETAILED ANALYSIS
OF ALTERNATIVES
MANAGEMENT DECISION FACTORS:
• Sao wd Community ArapUno
• Adtflonri teu
a treatability study(ies) required is dependent on site-
specific factors, the literature information available on
the technology, and technical expert judgment. The
latter two elements — the literature search and expert
consultation — are critical factors in determining if ade-
quate data are available or whether a treatability study is
needed to provide those data. Figure 2 provides a
decision tree for treatability studies in the RI/FS. Addi-
tional studies may not be needed if previous studies or
actual implementation have encompassed essentially
identical site conditions. The data and information on
which this decision is based should be documented.
Given the lack of full-scale experience with innovative
technologies, pilot-scale testing will generally be neces-
sary in support of remedy selection and implementation.
SUPERFUND PROCESS-TIMING OF
TREATABILITY STUDIES
Treatability studies should be planned and imple-
mented as soon as it is evident that insufficient informa-
tion is available in the literature to support the decision
necessary for remedy selection or implementation.
Treatability testing of technologies may begin during the
scoping phase, the initial phases of site characterization
and technology screening, and continue through the RI/
FS and into the RD/RA to support remedy implementa-
tion. Additional treatability studies of alternate tech-
nologies or treatment trains also may be needed later in
the RI/FS process as other promising remedial alterna-
tives are identified.
For many site types, initial data are available to
identify potentially applicable technologies early during
the scoping phase of the RI/FS for all or parts of the site.
In those cases, the literature search, the planning, and the
implementation of the treatability study can proceed.
The planning of the studies should coincide with the
scoping of the RI/FS to the extent practicable to ensure
that data are gathered during the RI to support the tech-
nologies and associated treatability studies.
Similarly, treatability studies to support the remedy
implementation also should be conducted as early in the
RD as appropriate. As with the RI/FS trcatability study,
additional technology-specific site characterization data
may be needed to aid in the design and implementation
of the study.
TREATABILITY STUDY GOALS
Each level of treatability study requires appropriate
performance goals. These goals should be specified be-
fore the test is conducted. The goals may need to be
reassessed to determine appropriateness following test-
-------
ing performance as a result of new information (e.g.,
ARARs), treatment train considerations or other factors.
Pre-ROD treatability study goals will usually be based
on the anticipated performance standards to be estab-
lished in the ROD. This is because cleanup criteria are
not finalized until the ROD is signed due to continuing
analyses and ARARs determinations. The treatability
goals should consider the following factors independ-
ently or in combination:
• Levels that are protective of human health and
the environment (e.g., contact, ingestion, leach-
ing) if treated waste is left unmanaged or is
managed;
• Levels that are in compliance with ARARs,
including the land disposal restrictions;
• Levels that ensure a reduction of toxicity, mobil-
ity, or volume;
• Levels acceptable for delisting of the waste; and
• Levels set by the State or Region for another site
with contaminated media with similar charac-
teristics and contaminants.
Further, the program has as the treatment goal and
expectation that treatment technologies and/or treatment
trains generally achieve a 90 percent or greater reduction
in the concentration or mobility of individual contami-
nants of concern. This goal complements the site-spe-
cific risk-based goals. There will be situations where re-
ductions outside this range that achieve health-based or
other site-specific remediation goals, may be appropri-
ate. Treatment technologies should be designed and op-
erated such that they achieve reductions beyond the
target level indicated to ensure that the stated goals are
achieved consistently.
Laboratory screening of treatability study goals al-
lows for a go/no-go decision. For example, the goal may
be a 50 percent reduction in mobility which would
indicate the potential to achieve greater reduction (e.g.,
90 percent) through additional refinement of the study.
The achievement of this goal might indicate the advisa-
bility of expending additional resources on a bench-scale
test to obtain a more definitive evaluation of the technol-
ogy. Bench- and pilot-scale testing goals are those
needed to select and/or implement the technology. For
example, the bench-scale testing goal for solidification/
stabilization could be to achieve a 90 percent or greater
reduction in mobility of the principal constituents. In
addition, the goals for the bench- or pilot-scale studies
also may involve multiple waste treatment levels — the
performance of which dictates the ultimate disposition
of the waste (i.e., clean closure or landfill closure).
Post-ROD treatability study goals should reflect
those performance standards specified in the ROD. They
should also be achieved in the most resource-efficient
manner.
ADMINISTRATIVE PLANNING
The planning process for treatability studies begins
during the budget cycle in the year prior to the planned
performance. At that time, the potential need for treata-
bility studies and their cost is estimated to ensure ade-
quate resources and to factor the study into the planning
for the site (e.g., scheduling the RI/FS). In many cases,
the RI/FS will not have been initiated at this time, and
assumptions will need to be made. In view of the limited
literature information that is currently available on tech-
nology performance, it is anticipated that one or more
treatability studies may be necessary for most sites.
Funding for treatability studies is separate from RI/FS
funding and is over and beyond the target of RI/FS cost
of$750K.
Planners need to take into consideration treatability
studies to be performed by contractors, EPA, and other
Federal Agencies (e.g., Corps of Engineers) to support
the ROD and the RD/RA. Treatability study funds will
be needed for Fund-lead sites and for selected Enforce-
ment-lead sites if the Responsible Party (RP) is not per-
forming the study. Funds also will be needed for
oversight of the studies. Oversight of Fund-lead treata-
bility studies will be allocated as part of the treatability
study. Oversight of RP-lead treatability studies will be
funded through the enforcement budget.
FUNDING
Treatability studies in support of the RI/FS or the
RD/RA are funded from the "Other Remedial" account
if they are Federally-funded. The amount of treatability
study funding required is dependent on technology and
site-specific factors. The section in this fact sheet en-
titled "Levels of Treatability Studies" provides a rough
estimate of resources and time required to perform the
studies. Resources required may vary greatly depending
on site conditions and data needs.
In the event that treatability study funding require-
ments exceed planned treatability study allocations (ei-
ther due to the costs of the studies or due to the need for
-------
studies which were not planned for), these studies should
be funded from the Region's "Other Remedial" account
or other Regional monies through the SCAP process.
Regions should contact Tom Sheckells (OERR/OPM,
FTS 382-2466) for clarifications.
All treatability studies, whether performed by a con-
tractor or EPA, are funded out of the Regional SCAP ac-
count. Procurement Requests (PR) used to initiate work
should have activity code "9" to ensure proper record
keeping.
CERCLIS
Treatability studies are coded in CERCLIS under the
event code "TS" that provides for separate event coding
for each treatability study for a given site. This allows for
multiple treatability studies with separate funding (e.g.,
Federal-, State-, or Responsible Party-lead treatability
studies).
PERFORMANCE OF TREATABILITY
STUDIES
Fund-lead treatability studies generally will be con-
ducted through the REM or ARCS contractors or their
sub-contractors or contractors working for States. A list
of vendors that, have expressed interest in performing
treatability studies has been compiled in the "Inventory
of TreatabiJity Study Vendors." A preliminary draft
copy is scheduled for distribution in January 1990. Com-
panies on this list should be notified of requests for pro-
posals (RFPs) for treatability studies in accordance with
the Federal Acquisition Regulations.
EPA and other Federal Agencies such as the Bureau
of Mines also may perform select treatability studies on
a case-by-case basis. Again, the funding of these activi-
ties is through the Regional SCAP allocations.
Enforcement-lead treatability studies generally will
be accomplished through the RP contractor. There may
be exceptions to this where the complexity of the site
requires alternative options (e.g., State- or Federal-lead
treatability studies for all or part of a site). The planning
and performance of the study should be directed by the
Region to ensure that the study results in the type and
quality of data needed to support the decision.
TREATABILITY STUDY PROTOCOLS
Treatability studies need to be carefully planned to
ensure that sufficient data of known, documented, and
appropriate quality are generated to support the decision.
The site-specific treatability study protocol is outlined in
the Work Plan and the Sampling and Analysis Plan.
These plans should, among other things, clearly de-
scribe: the experimental design, the treatability study
goals, the Quality Assurance Project Plan, data manage-
ment and interpretation, and reporting.
The treatability study work assignment is to require
that the treatability study be developed in accordance
with Agency guidance, factoring in literature, site-spe-
cific information, and expert consultation. The "Guide
for Conducting Treatability Studies Under CERCLA"
provides a general approach for treatability studies and
provides a protocol for the preparation of the Work
Assignment, Work Plan, Sampling and Analysis Plan,
Health and Safety Plan, and the Community Relations
Plan. The Agency also is developing a number of
technology-specific treatability guidances which should
be followed; the first of these on soil washing is sched-
uled to be issued in the second quarter of FY 1990. For
more information on these documents, other sources of
treatability .study information, and for technical assis-
tance in reviewing and performing treatability studies
please contact Ben Blaney (ORD) at FTS/684-7406 or
com. 513/596-7406.
TREATABILITY STUDY REPORT
The Agency has initiated an effort to ensure the
consistency of treatability study reports and to provide a
central repository of treatability studies to facilitate
information dissemination. The "Guide for Conducting
Treatability Studies under CERCLA" contains a stan-
dard report format that is to be followed for all treatabil-
ity study reports. All work assignments and consent
decrees are to contain a statement requiring that docu-
ments be developed in accordance with Agency policy.
Further, all Fund-lead and enforcement-lead over-
sight treatability work assignments are to include a
provision requiring that a camera-ready master copy of
the treatability study report be sent to the following
address:
Attn: KenDostal
U.S. Environmental Protection Agency
Superfund Treatability Data Base
ORD/RREL
26 W. Martin Luther King Drive
Cincinnati, Ohio 45268
Information contained in these reports will be available
through the Alternative Treatment Technology Informa-
tion Center (ATTIC). For more information on ATTIC
please call FTS 382-5747 or com. 202/382-5747.
-------
TECHNICAL ASSISTANCE
Literature information and consultation with experts
are critical factors in determining the need for and
ensuring the usefulness of treatability studies. A refer-
ence list of sources on treatability studies is provided in
the "Guide for Conducting Treatability Studies Under
CERCLA."
It is recommended that a Technical Advisory Com-
mittee (TAG) be used. This committee may include ex-
perts on the technology(ies) to provide technical support
from the scoping phase of the treatability study through
data evaluation. Members of the TAG may include
representatives from EPA (Region and/or ORD), other-
Federal Agencies, States,'and consulting firms. Techni-
cal assistance may be obtained through the following:
• The Office of Research and Development
(ORD) provides technical assistance on site
remediation and treatability studies. The Super-
fund Technical Assistance Response Team
(START) provides long-term site-specific sup-
port from the scoping phase through remedial
design for sites identified by Regional manage-
ment and selected for START support. The
Technical Support Project (TSP) provides short-
term support of a similar nature. ORD assis-
tance in the planning, performance, and/or re-
view of treatability studies can be accessed
through either mechanism. ORD also has the
Treatability Assistance Program (TAP) which is
developing technology-sped fie treatability stu dy
protocols, bulletins, and a computerized data-
base. For further information on treatability
study support or the TAP please contact Ben-
Blaney (ORD) at FTS 684-7406 or com. 5137
569-7406, Rich Steimle (OSWER) at FTS 382-
7914 or com. 202/382-7914, or a Regional
Forum member.
Bureau of Mines (BOM) has technical exper-
tise and experience in the development of tech-
nologies to remove metals and other inorganic
chemicals from solids and liquids. Contact Wil-
Ijam Schmidt at FTS 634-1210orcom. 202/634-
1210 for information.
The U.S. Army Corps of Engineers (COE)
may perform or oversee treatability studies
required for RI/FS or RD/RA. For informa-
tion, contact Joe Grasso (COE) at com. 402/
691-4532.
FOR FURTHER INFORMATION
In addition to the contacts identified above, the
appropriate Regional Coordinator for each Region lo-
cated in the Hazardous Site Control Division/Office of
Emergency and Remedial Response or the CERCLA
Enforcement Division/Office of Waste Programs En-
forcement should be contacted for additional informa-
tion or assistance.
-------
&EPA
United States
Environmental Protection
Agency
Office of Research and
Development
Washington DC 20460
Office of Solid Waste and
Emergency Response
Washington, DC 20460
Super) und
EPA/540/R-92A)71a
October 1992
Guide for Conducting
Treatability Studies under
CERCLA
Final
-------
EPA'54C'-R-92'C7ia
OSWER Directive No. 9380.3-10
November 1992
GUIDE FOR CONDUCTING
TREATABILITY STUDIES UNDER CERCLA
FINAL
Risk Reduction Engineering Laboratory
Olfice of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
and
Office of Emergency and Remedial Response
Olfice of Solid Waste and Emergency Response
U.S. Environmental Protection Agency
Washington, DC 20460
Prinled on Recycled Paper
-------
NOTICE
The information in this document has been funded wholly or in part by
the U.S. Environmental Protection Agency (EPA) under Contract No.
68-C9-0036. It has been subjected to the Agcncy'srcvicw process and
approved for publication as an EPA document.
The policies and procedures set forth here arc intended as guidance to
Agency and other government employees. They do not constitute
rulcmaking by the Agency, and may not be relied on to create a
subsiamivc or procedural right enforceable by any other person. The
Government may take action thai is ai variance with the policies and
procedures in this manual. Mention of trade names or commercial
products docs nol constitute endorsement or recommendation for use.
-------
FOREWORD
Today's rapidly developing and changing technologies and industrial
products and practices frequently carry with them the increased gen-
eration of materials that, if improperly dealt with, can threaten both
public health and the environment. The U.S. Environmental Protec-
tion Agency (EPA) is charged by Congress with protc ;ting theNation's
land, air, and water resources. Under a mandate of national environ-
mental laws, the Agency strives to formulate and implement actions
leading to a compatible balance between human activities and the
ability of natural systems to support and nurture life. These laws direct
the EPA to perform research to define our environmental problems,
measure the impacts, and search for solutions.
The Risk Reduction Engineering Laboratory is responsible for plan-
ning, implementing, and managing research, development, and dem-
onstration programs to provide an authoritative, defensible engineer-
ing basis in support of the policies, programs, and regulations of the
EPA with respect to drinking water, wastcwalcr, pesticides, toxic
substances, solid and hazardous wastes, and Superfund-rclated activi-
ties. This publication is one of the products of that research and
provides a vital communication link between the researcher and the
user community.
The purpose of this guide is to provide information on conducting
treatability studies. It describes a three-tiered approach that consists of
1) remedy screening, 2) remedy-selection testing, and 3) remedial
design/remedial action testing. It also presents a protocol for conduct-
ing treatability studies in a systematic and stepwise fashion for deter-
mination of the effectiveness of a technology (or combination of
technologies) in remediating a CERCLA site.
E.Timothy Oppelt, Director
Risk Reduction Engineering Laboratory
111
-------
ABSTRACT
Systematically conducted, well-documented treatability studies are an
important component of the removal process, remedial investigation/
feasibility study (RI/FS) process and the remedial design/remedial
action (RD/RA) process under the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA). These stud-
ies provide valuable site-specific data necessary to aid in the screening,
selection, and implementation of the site remedies. This guide focuses
on both treatability studies conducted in support of remedy screening
and selection [i.e., pre-Record of Decision (ROD)] and treatability
studies in support of remedy implementation (i.e., post-ROD).
The guide describes a three-tiered approach for conducting trealability
studies that consists of 1) remedy screening, 2) remedy-selection
testing, and 3) RD/RA testing. Depending on the technology infor-
mation gathered during RI/FS scoping, pre-ROD trcatabilily studies
may bcgn. at cither the remedy-screening or remedy-selection tier.
Remedial design/remedial action trcatabilily testing is performed post-
ROD.
The guide also presents an 11-stcp generic protocol for conducting
treaiabiliiy studies. The steps include:
• Establishing data quality objectives
• Identifying sources for treatability studies
• Issuing the Work Assignment
• Preparing the Work Plan
• Preparing the Sampling and Analysis Plan
• Preparing the Health and Safety Plan
• Conducting community relations activities
• Complying with regulatory requirements
• Executing the study
• Analyzing and interpreting the data
• Reporting the results
The intended audience for this guide comprises Remedial Project
Managers, On-Scenc Coordinators, Federal facility environmental
coordinators, potentially responsible parties, contractors, and technol-
ogy vendors. Although Resource Conservation and Recovery Act
(RCR A) program officials may find many sections of this guide useful,
the RCRA program is not expressly addressed in the guide.
IV
-------
TABLE OF CONTENTS
Section Page
NOTICE ii
FOREWORD iii
ABSTRACT iv
FIGURES vi
TABLES vii
ACRONYMS viii
ACKNOWLEDGMENTS ix
1. Introduction 1
1.1 Background 1
1.2 Purpose 1
1.3 Intended Audience 1
1.4 History of the Guide 2
1.5 Use of the Guide 2
2. Overview of Trcatabilily Studies 5
2.1 The Role of Trcatability Studies Under CERCLA 5
2.2 Three-Tiered Approach to Treatability Testing 7
2.3 Applying the Tiered Approach 12
2.4 Treatability Study Test Objectives 1?
2.5 Special Issues 15
3. Protocol for Conducting Trcauibility Studies 23
3.1 Introduction 23
3.2 Establishing Daui Quality Objectives 23
3.3 Identifying Sources for Trcatability Studies 26
3.4 Issuing the Work Assignment 29
3.5 Preparing the Work Plan 31
3.6 Preparing the Sampling and Analysis Plan 35
3.7 Preparing the Health and Safety Plan 38
3.8 Conducting Community Relations Activities 39
3.9 Complying With Regulatory Requirements 41
3.10 Executing the Study , 45
3.11 Analyzing and Interpreting the Dam 46
3.12 Reporting the Results 52
REFERENCES 55
APPENDIX A. Sources of Trcauibilily Information 57
APPENDIX B. Cost Elements Associated with Trcatability Studies 61
APPENDIX C. Technology-Specific Characterization Parameters 65
-------
FIGURES
Figure Page
1 Decision tree showing when treatabilily studies are needed to support the evaluation and selection of an
alternative 6
2 The role of trcatability studies in the RI/FS and RD/RA process 9
3 Flow diagram of the tiered approach 14
4 Information contained in the ORD Inventor)' of Treaiability Study VenJors 28
5 Example test matrix for zeolite amendment remedy-selection treatabilily study 32
6 Example project schedule fora two-tiered chemical dehalogcnation ueatabilily study 36
7 Example project organization chart 37
8 Facility requirements for treatability testing 42
9 Shipping requirements for offsite treatability testing 43
10 Evaluation criteria and analysis factors for detailed analysis of alternatives 48
11 General applicability of cost elements to various treatability study tiers 62
VI
-------
TABLES
Table
1 General Comparison of Remedy-Screening. Remedy-Selection, and RD/RA Treaiability Studies ................... 8
2 Aqueous Field Treatability Studies: Generic Versus Vendor Processes [[[ 20
3 Soils/Sludges Field Treatability Studies: Generic Versus Vendor Processes .................................................. 20
4 Summary of Three-Stage DQO Development Process [[[ 24
5 PARCC Parameters [[[ 25
6 Suggested Organization of Treatability Study Work Assignment [[[ 30
7 Suggested Organization of Treatabilily Study Work Plan [[[ 31
8 Typical Waste Parameters Needed to Obtain Disposal Approval at an Offsitc Facility ................................... 34
9 Suggested Organization of a Treatability Study Sampling and Analysis Plan .................................................. 38
10 Suggested Organization of a Trcatabiliiy Study Health and Safety Plan [[[ 39
1 1 Suggested Organization of Community Relations Plan [[[ 40
12 Regional Offsite Contacts for Determining Acceptability of Commercial Facilities
to Receive CERCLA Wastes [[[ 45
-------
ACRONYMS
AOC Administrative Order on Consent OSWER
ARAR applicable or relevant and appropriate
requirement PARCC
ARCS Alternative Remedial Contracts Strategy
ATTIC Alternative Treatment Technology PAH
Information Center PCB
CERCLA Comprehensive Environmental Response, PRP
Compensation, and Liability Act of 1980 (aka QAPP
Supcrfund) QA/QC
CFR Code of Federal Regulations R A
COLIS Computerized On-Line Information Service RCRA
COE U.S. Army Corps of Engineers
CRP Community Relations Plan RD
DOD Department of Defense RD&D
DOE Department of Energy RFP
DOT Department of Transportation RI
DQO Data quality objective ROD
EPA U.S. Environmental Protection Agency RPM
ERCS Emergency Response Cleanup Services RREL
ERT Emergency Response Team SAP
ETSC Engineering Technical Support Center SARA
FAR Federal Acquisition Regulations
FR Federal Register SCAP
FS feasibility study
FSP Field Sampling Plan SITE
HSP Health and Safety Plan
HSWA Hazardous and Solid Waste Amendments of SOP
1984 SOW
ITSV Inventory of Trcatability Study Vendors START
LDRs Land Disposal Restrictions
MCLs Maximum Contaminant Levels TAT
MSDS Material Safety Data Sheet TCLP
NCP National Oil and Hazardous Substances TIX
Pollution Contingency Plan TOC
NIOSH National Institute for Occupational Safety and TOX
Health ' TSDF
NPL National Priorities List TSC
O&M Operation and Maintenance TSP
OERR Office of Emergency and Remedial Response TST
ORD Office of Research and Development USCG
OSC On-Scene Coordinator USPS
OSHA Occupational Safety and Health Administration UST
Office of Solid Waste and Emergency
Response
Precision, Accuracy, Representativeness,
Completeness, and Comparability
Polynuclear Aromatic Hydrocarbon
Polychlorinated biphenyl
Potentially responsible party
Quality Assurance Project Plan
quality assurance/quality control
remedial action
Resource Conservation and Recover)' Act
of 1976
remedial design
research, development, and demonstration
request for proposal
remedial investigation
Record of Decision
Remedial Project Manager
Risk Reduction Engineering Laboratory
Sampling and Analysis Plan
Superfund Amendments and Reauthoriza-
tion Act of 1986
Superfund Comprehensive
Accomplishments Plan
Superfund Innovative Technology
Evaluation
standard operating procedure
Statement of Work
Superfund Technical Assistance Response
Team
Technical Assistance Team
toxicity characteristic leaching procedure
Technical Information Exchange
total organic carbon
total organic halogen
treatment, storage, or disposal facility-
Technical Support Center
Technical Support Project
Technical Support Team
United States Coast Guard
United States Postal Service
Underground Storage Tank
Vlll
-------
ACKNOWLEDGMENTS
This guide: was prepared for the U.S. Environmental Protection Agency, Office of
Research and Development, Risk Reduction Engineering Laboratory (RREL), Cincin-
nati, Ohio, by IT Corporation. Mr. Eugene F. Harris and Mr. David L. Smith served
as the EPA Technical Project Monitors, assisted by Ms. Robin M. Anderson. Office
of Emergency and Remedial Reponse, and Mr. Jonathan Herrmann, RREL. Mr.
Gregory D. McNeily was IT's Work Assignment Manager. The project team included
Jeffrey S.Davis, Mary Beth Foerst, E.RadhaKrishnan, Jennifer Plait, Michael Taylor,
and Julie Van Deuren. Ms. Judy L. Hessling served as IT's Senior Reviewer, and Ms.
Martha H. Phillips served as the Technical Editor. Document layout was provided by
MJ. James I. Scott, III.
The following personnel have contributed their time and comments by participating in
the Guide for Conducting Treatability Studies Under CERCLA workshop:
Lisa Askari
John Barich
Edward Bates
Benjamin Blaney
John Blevins
Randall Brecden
JoAnn Camacho
Jose Cisncros
Paul Flathman
Vance Fong
Frank Freestone
Tom Greengard
Eugene Harris
Sarah Hokanson
Norm Kulujian
Donna Kuroda
John Quandcr
Jim Rawe
Ron Turner
U.S. EPA, Office of Solid Waste
U.S. EPA, Region X
U.S. EPA, Risk Reduction Engineering Laboratory
U.S. EPA, Risk Reduction Engineering Laboratory
U.S. EPA, Region IX
U.S. EPA, Office of Emergency and Remedial Response
U.S. EPA, Environmental Response Team
U.S. EPA, Region V Emergency Response
OHM Remediation Services Corporation
U.S. EPA, Region IX
U.S. EPA, Risk Reduction Engineering Laboratory
EG&G Rocky Flats
U.S. EPA, Risk Reduction Engineering Laboratory
Clean Sites, Inc.
U.S. EPA, Region III
U.S. Army Corps of Engineers
U.S. EPA, Technology Innovation Office
Science Applications International Corporation
U.S. EPA, Risk Reduction Engineering Laboratory
IX
-------
SECTION 1
INTRODUCTION
1.1 Background
Under ihc Supcrfund Amendments and Rcauihori/.aiion
Aci of 1986 (SARA), the U.S. Environmental Proicclion
Agency (EPA) is required lo select remedial actions in-
volving treatment ihai "permanently and significantly re-
duces the volume, toxicity, or mobility of the hazardous
substances, pollutants, and contaminants" [Comprehensive
Environmental Response, Compensation, and Liability Act
(CERCLA), Section 121(b)].
Selection of remedial actions involves several risk manage-
ment decisions. Uncertainties with respect to performance,
reliability, and cost of treatment alternatives underscore the
need for well-planned, well-conducted, and well-docu-
mented (Testability studies, as evident in the following
quote from Management Review of the Superfund Program
(EPA 1989a):
"To evaluate the application of treatment tech-
nologies 10 particular sites, it is essential to con-
duct laboratory or pilot-scale tests on actual wastes
from the site, including, if needed and feasible,
tests of actual operating units prior to remedy
selection. These 'treatability tests' arc not currently
being performed at many sites to the necessary
extent, or their quality is not adequate to support
reliable decisions."
Treatability studies provide valuable site-specific data nec-
essary to support Supcrfund remedial actions. They serve
two primary purposes: 1) to aid in the selection of the
remedy, and 2) to aid in the implementation of the selected
remedy. Treatability studies conducted during a remedial
investigation/feasibility study (Rl/FS) indicate whether a
given technology can meet the expected cleanup goals for
the site and provide important information to aid in remedy
selection, whereas ircatability studies conducted during
remedial design/remedial action (RD/RA) establish the de-
sign and operating parameters necessary for opiimi/ation
of technology performance and implementation of a sound,
cost-effective remedy. Although the purpose and scope of
these studic> differ, they complement one another because
information obtained in support of remedy selection may
also be used to support the remedy design and implementa-
tion. Treatability studies also may be conducted under the
CERCLA Removal Program to support removal actions
that involve treatment.
Historically, ircatability studies have been delayed unu'l after
the Record of Decision (ROD) has been signed. Although
certain post-ROD ireatability studies arc appropriate, con-
ducting treatability studies during the RI/FS (i.e., prc-ROD)
should reduce the uncertainties associated with selecting the
remedy, provide a sounder basis for the ROD, and possibly
facilitate negotiations with potentially responsible panics with-
out lengthening the overall cleanup schedule for the site.
Because ircatability studies may be expensive and time-
consuming, however, the economics of cost and time must be
taken into consideration when planning trcaiability studies in
support of the various phases of the Supcrfund program.
1.2 Purpose
This document presents guidance on conducting ircaubility
studies under CERCLA. Us purpose is to facilitate efficient
planning, execution, and evaluation of trcatability studies
and to ensure that the data generated can support remedy
selection and implementation.
1.3 Intended Audience
This document is intended for use by EPA Remedial Project
Managers (RPMs), EPA On-Sccnc Coordinators (OSCs),
potentially responsible parties (PRPs), Federal facility en-
vironmental coordinators, trcatabiliiy study contractors, and
technology vendors. As described here, each of these
persons plays a different role in conducting ircaiabiliiy
studies under CERCLA. Although the Resource Conserva-
tion and Recovery Act (RCRA) program is noi expressly
-------
addressed, many sections of the guide may be useful in the
planning of trcatability studies in support of corrective
action. Some parts may also be applicable in the Under-
ground Storage Tank (UST) program.
1.3.1 Remedial Project Managers
Remedial Project Managers arc EPA or State officials re-
sponsible for remediation planning and oversight at a site.
Their role in trcatabiliiy investigations depends on the des-
ignated lead agency (Federal, State, or private) and whether
the site is a fund-financed or enforcement-lead site. Their
activities generally include scoping the treatabiliiy study,
establishing the data quality objectives, selecting a contrac-
tor, and issuing a work assignment, or obtaining EPA-
sponsorcd trcaiabilily study support, overseeing the execu-
tion of the study, informing or involving the public as
appropriate, reviewing project dclivcrables, and using
treatability study data in decision making.
7.3.2 On-Scene Coordinators
On-Scene Coordinators arc Federal officials prcdesignatcd
by the EPA or U.S. Coast Guard (USCG) to coordinate and
direct removal actions at both National Priorities List (NPL)
and non-NPL sites. Their role in treatabiliiy studies is
similar to that of the RPM.
7.3.3 Potentially Responsible Parties
Under CERCLA Sections 104(a) and 122(a), EPA has the
discretion to allow PRPs to perform certain Rl/FS activi-
ties, including trcatability studies. The EPA or an autho-
rized State agency oversees the conduct of PRP-lcd
trcatabilily studies, but the PRP is responsible for project
planning, execution, and evaluation.
7.3.4 Federal Facility Environmental
Coordinators
Environmental coordinators at Federal facilities may con-
duct trcatability studies under CERCLA or agency-specific
programs such as the Department of Defense (DOD) Instal-
lation Restoration Program and the Department of Energy
(DOE) Environmental Restoration and Waste Management
Program. The roles and responsibilities of these personnel
will vary by agency and program; however, for trcaiabilily
studies they will be similar to those of the EPA RPM.
7.3.5 Contractors/Technology Vendors
Treatability studies arc generally performed by remedial
contractors or technology vendors. Their roles in ircatability
investigations include preparing the Work Plan and other
supporting documents, complying with regulator) require-
ments, executing the study, analy/.ing and interpreting the
data, and reporting the results.
1.4 History of the Guide
In December 1989, EPA published the interim final Guide
for Conducting Treaiability Studies Under CERCLA (EPA
1989b). This generic trcatabilily guidance was one compo-
nent of the EPA's Office of Research and Development
(ORD) trcaiability study initiative to identify trcatability
capabilities, to consolidate trcatabilily data, and to develop
standard operating protocols. The objectives of the guide
were threefold:
1) To provide guidance to RPMs and Supcrfund re-
medial contractors for conducting trcauibiliiy stud-
ies in support of remedy selection (i.e., prc-ROD;.
2) To serve as a framework for developing technol-
ogy-specific protocols.
3) To be a dynamic document thai evolves as the
Agency gains trcaiabilily study experience.
As part of the development of the generic trcaiability guid-
ance, EPA sponsored a trcatability protocol workshop in
July 1989, which was attended by more than 60 representa-
tives from EPA Headquarters and Regional offices, con-
tractors/technology vendors, and acadcmia. The tiered
approach to treatabiliiy studies and the 11-step protocol
that evolved during the workshop and subsequent docu-
ment peer review process form the basis of the trcaiabilily
guidance.
In keeping with the original objcciivc of producing a dy-
namic document, comments on the utility of the interim
final guidance after approximately 18 months of use were
solicited through a survey of potcmial users (principally
RPMs and their contractors) and a second workshop in
August 1991. Although the general content and format
have not changed, the document has been expanded to
address a broader audience and updated to reflect current
regulations, policy, and guidance/information sources. In
addition, the "tier" terminology has been revised to reflect
the intended use of the data rather than the scale of testing.
1.5 Use of the Guide
7.5.7 Organization of the Guide
The guide is organixcd into iwo principal sections: an
-------
overview of ireatability studies and a stcp-by-sicp protocol.
Section 2 describes the need for trcatability studies and
presents a three-tiered approach consisting of 1) remedy
screening, 2) remedy selection, and 3) remedial design/
remedial action. This section also describes the application
of the tiered approach to innovative technologies, treatment
trains, and in situ technologies; circumstances in which
treatability studies can and cannot be performed generi-
cally; and PRP-conductcd ireauibility studies.
Section 3 presents a general approach or protocol for con-
ducting treatability studies, li contains information on
planning, performing, and reporting the results of treatabilily
studies with respect to the three ucrs. Specifically, this
section include information on:
• Establishing data quality objectives.
• Identifying qualified sources for performance of
treatability studies and selecting a contracting mecha-
nism.
• Issuing the work assignment, with emphasis on writ-
ing the scope of work.
• Preparing the Work Plan, with emphasis on designing
the experiment.
• Preparing the Sampling and Analysis Plan for a
treatability study.
• Preparing the Health and Safety Plan for a treatability
study.
• Conducting community relations activities in support
of treatability studies.
• Complying with regulatory requirements for testing
and residuals management.
• Executing the trcatability study, with emphasis on col-
lecting and analyzing samples.
• Analyzing and interpreting the data, including a dis-
cussion on statistical analysis techniques.
• Reporting the results in a logical and consistent format.
The text of each subsection presents general information
followed (when applicable) by specific details pertaining to
the three tiers of ireatability testing.
Appendix A contains additional source of ucaunility
information. Appendix B discusses the major cost ele-
ments associated with trcatability studies. Appendix C
contains technology-specific wastc-charactcri/ation pa-
rameters.
7.5.2 Application and Limitations of the
Guide
Treatability studies are an integral part of the Supcrfund
program. This guide is intended to supplement the infor-
mation on development, screening, and analysis of alterna-
tives contained in the interim final Guidance for Conduct-
ing Remedial Investigations ana Feasibility Studies Under
CERCLA (EPA 1988a), hereinafter referred to as the RI/FS
guidance. Generic in nature, the guide encompasses all
waste matrices (soils, sludges, liquids, and gases) and all
categories of technologies (biological treatment, physical/
chemical treatment, immobilization, thermal treatment, and
in situ treatment). The guide addresses trcatahility studies
conducted in support of remedy screening and selection
(i.e., prc-ROD) and remedy design and implementation
(i.e., post-ROD). Companion documents providing tech-
nology-specific ircatability guidance arc being prepared for
soil vapor extraction, chemical dchalogcnalion, soil wash-
ing, solvent extraction, biodcgradation, thermal dcsorption,
and solidification/stabilization.
In an effort to be concise, supporting information in other
readily available guidance documents is referenced through-
out this guide rather than repeated. For example, details on
the preparation of a site Sampling and Analysis Plan (which
includes a Field Sampling Plan and a Quality Assurance
Project Plan), a Health and Safety Plan, and a Community
Relations Plan arc not included herein.
Although this guidance is written to support the ircaiability
study activities of an EPA RPM under CERCLA, it has
wide applicability to many other programs. For this reason,
the term "project manager" has been used, when appropri-
ate, to signal the potential applicability of the subject cov-
ered to both the CERCLA Remedial and Removal Pro-
grams and to non-CERCLA trcauibility studies.
This document was drafted and reviewed by representa-
tives from EPA's Office of Solid Waste and Emergency
Response, Office of Research and Development, and the
Regional offices, as well as by contractors and vendors
who conduct trcauibility studies. Comments obtained dur-
ing the course of the peer review process have been inte-
grated or addressed throughout this guide.
-------
SECTION 2
OVERVIEW OF TREATABILITY STUDIES
This section presents an overview of ireatability studies
under CERCLA and provides examples of the application
of treaiability studies in the RI/FS process. Subsection
2.1 outlines the role of trcauibiliiy studies in the Super-
fund program. Subsection 2.2 provides details on the
three tiers of trcaiabiliiy testing. Subsection 2.3 presents
the methodology for applying the tiered approach. Sub-
section 2.4 discusses treatability study test objectives.
Subsection 2.5 addresses special issues associated with
CERCLA treatabiliiy studies, including examples of how
the tiered approach can be applied to investigations of unit
operations, treatment trains, and in situ technologies; when
testing can and cannot be performed generically (i.e.,
without the assistance of vendors using proprietary re-
agents and processes); the involvement and oversight of
PRPs; and the funding of ircaiability studies.
2.1 The Role of Treatability Studies
Under CERCLA
2.1.1 Pre-ROD Treatability Studies
As discussed in the RI/FS guidance, site charactcri/jtion
and treaiability investigations arc two of the main compo-
nents of the RI/FS process. As siic and technology infor-
mation is collected and reviewed, additional data needs
for evaluating alternatives arc identified. Trcaiabiliiy
studies may be required to fill some of these dam gaps.
In the absence of data in the available technical literature,
treatabiliiy studies can provide the critical performance
and cost information needed to evaluate and select treat-
ment alternatives. The purpose of a prc-ROD trcaubility
investigation is to provide the data needed for the dcuiilcd
analysis of alternatives during the FS. The 1990 revised
National Oil and Hazardous Substances Pollution Contin-
gency Plan (NCP) (55 FR 8813), Section 3()(>.43()(c),
specifies nine evaluation criteria to be considered in this
assessment of remedial altcrnaiivcs. Trcaiabiliiy studies
can generally provide dam to address the firsi seven of
these nine criteria;
1) Overall protection of human health and ihc en-
vironment
2) Compliance with applicable or relevant and ap-
propriate requirements (ARARs)
3) Long-term effectiveness and permanence
4) Reduction of toxicily, mobility, and volume
through treatment
5) Short-term effectiveness
6) Implcmenuibiliiy
7) Cosl
8) Slate acceptance
9) Community acceptance
The first iwo criteria, which relate directly to ihc statutory
requirements each remedial alternative must meet, arc
catcgori/ed as threshold criteria. The next five arc the
primary balancing criteria upon which the selection of
the remedy is based. The final two modifying criteria,
Slate acceptance and community acceptance, arc addressed
in the ROD when comments arc received on the RI/FS and
the proposed remedial plan. (The RI/FS evaluation criic-
ria arc discussed in detail in Subsection 3.11.2.)
Prc-ROD ircaiability studies may be needed when poten-
tially applicable treatment technologies arc being consid-
ered for which no or limited performance or cost informa-
tion is available in the liicraiurc with regard to ihc wasic
-------
types and site conditions of concern. The general decision
tree presented in Figure 1 illustrates when trcatability
studies arc needed to support the evaluation and selection
of an alternative. After the existing data on the physical
and chemical characteristics of the waste have been re-
viewed, a literature survey is conducted to obtain any
existing trcatability data for the contaminants and matri-
ces of concern. (Sources of technical support and
ireatahiHty information available through EPA are dis-
cussed in Subsection 3.3 and Appendix A.) Based on the
results of a review of available site data and a literature
search, remedial technology types arc prcscrecncd to elimi-
nate those that arc clearly not applicable for the site.
Potentially and definitely applicable technologies arc as-
sembled into alternatives and evaluated in terms of the
nine RI/FS criteria to identify any data gaps. Site- and
technology-specific data needs arc then identified for each
of the alternatives retained for investigation.
The need to conduct a trcatability study on any part of an
alternative is a management decision. In addition to the
technical considerations, certain nontechnical management
decision factors must be considered. As shown in Figure
1, these factors include the expected level of State and
community acceptance of a proposed alternative; lime
constraints on the completion of the RI/FS and the signing
of the ROD; and the appearance of new site, waste, or
technology data.
If the existing data arc adequate for an evaluation of the
alternative for remedy selection (i.e., sufficient to perform
a detailed analysis against the nine RI/FS evaluation crite-
ria), no trcatability study is required. Otherwise, a
trcatability study should be performed to generate the data
necessary to conduct a detailed analysis of the alternative.
2.1.2 Post-ROD Treatability Studies
Although a substantial amount of data on the selected
remedy may be available from the RI/FS. treatability stud-
ies may also be necessary during remedial design/reme-
dial action if treatment is part of the remedy. Post-ROD
or RO/RA trcatability studies can provide the detailed
design, cost, and performance data needed to optimize
treatment processes and to implement full-scale treatment
systems. In the process of implementing a remedy, RD/
RA trcatability studies can be used 1) to select among
multiple vendors and processes within a prescribed rem-
edy (prequalificaiion), 2) to implement the most appropri-
ate of the remedies prescribed in a Contingency ROD, or
3) to support preparation of the Agency's detailed design
specifications and the design of treatment trains.
REVIEW AVAILABLE
SITE DATA
SEARCH LITERATURE
TO OBTAIN EXISTING
TREATABILITY DATA
IDENTIFY
DATA GAPS
YES
MANAGEMENT DECISION FACTORS
• Sun ind Commumry Acnpunce |
• Scnt
-------
provided with a standard sample of waste. Each vendor
designs and performs a ireaiability study based on that
sample and provides treatment results to the lead agency.
The lead agency uses these results to determine which
vendors are qualified to bid on the RA. Generally, the
vendor should achieve results equivalent to the cleanup
criteria defined in the ROD to be considered for
prequalification.
This prequalification approach has been used at the Selma
Treating Company Superfund Site, Region 9. Selma, Cali-
fornia.' Part 9 of the Federal Acquisition Regulations
(FAR) describes policies, standards, and procedures ap-
plicable to this approach.
Contingency RODs
There are situations in which additional flexibility in the
ROD may be required to ensure implementation of ihe
most appropriate technology for a site. In these cases, the
selected remedy may be accompanied by a proven contin-
gency remedy in a Contingency ROD. The Contingency
ROD option was developed for two purposes: 1) to pro-
mote the use of innovative technologies, and 2) to allow
different technologies offering comparable performance
to be carried through to remedial design.
Although treatability studies of an innovative technology
will be conducted during the Rl/FS to support remedy
selection, it may not be feasible to conduct sufficient
testing to address all of the significant uncertainties asso-
ciated with the implementation of this option. This situa-
tion, however, should not cause the option to be screened
out during the detailed analysis of alternatives in the FS.
If the performance potential of an innovative technology
indicates this technology would provide the best balance
of tradeoffs from among the options considered despite
its uncertainties, CERCLA Section 12l(b)(2) provides
support for selecting such a technology in the ROD.
Implementation of the technology, however, may be con-
tingent upon the results of RD/RA ireatabiliiy testing.
When an innovative technology is selected and its perfor-
mance is to be verified through additional trcatability
testing, a proven treatment technology may also be in-
cluded in the ROD as a contingency remedy. In the event
the RD/RA treatability study results indicate that the full-
scale innovative remedy cannot achieve the cleanup goals
at the site, the contingency remedy could then be imple-
mented.
If two different technologies for treatment of the same
contaminant/matrix emerge from the FS and each offers
comparable performance with respect to the five primary
balancing criteria so that either one could provide the best
balance of tradeoffs, one of the alternatives may be named
in the ROD as the selected remedy and the other as the
contingency remedy. Based on the results of post-ROD
RD/RA treatability testing, the most appropriate remedy
can then be identified and implemented.
Detailed Design Specifications
To support the remedial action bid package, the lead
agenry may choose to develop detailed design specifica-
tions. If technical data available from the Rl/FS arc
insufficient for design of the remedy, an RD/RA treat-
ability study may be necessary. Post-ROD ircatability
studies can provide the detailed cost and performance data
required for optimization of the treatment processes and
the design of a full-scale treatment system.
If an RD/RA trcatabilily study is required to support the
detailed design specifications, the designer will be re-
sponsible for planning the study and defining the perfor-
mance goals and objectives. Trcatabilily study oversight
will be provided by the RPM and the Oversight Assistant.
Post-ROD RD/RA trcaiability studies can also be per-
formed to support the design of treatment trains. Al-
though all parts of a treatment train may be effective for
treating the wastes, matrices, and residuals of concern,
issues such as unit sizing, materials handling, and systems
integration must also be addressed. Trcaiability studies of
one unit's operations can assist in identifying characteris-
tics of the treated material that may need to be taken into
consideration in the design of later units. A trcatability
study of the entire train can then provide data to confirm
compliance with ARARs and the cleanup criteria outlined
in the ROD. Because a treatment train will often involve
several different technologies and vendors, the designer
will coordinate ireaiability testing of the entire system and
prepare the final ircatability study report.
2.2 Three-Tiered Approach to
Treatability Testing
Trcaiability sludics arc laboratory or field tests designed
10 provide critical data needed 10 evaluate and implement
remedial treatment technologies ai waste siles. As an aid
in ihe planning and performance of cosi-cffcciivc, on-
limc, scientifically sound trcatabilily siudics, a ihrcc-
liercd approach has been developed. The ihrcc-iicrcd
approach applies 10 all ireaiability siudics conducted in
-------
suppon of Superfund site remediation. Figure 2 presents
the treatabilily tiers and iheir conceptual relationship to
the RI/FS and the RD/RA processes. Table 1 lists general
similarities and differences among the three tiers.
2.2.1 Technology Prescreening and
Treatability Study Scoping
Prescreening is an important first step in the identification
of potentially applicable treatment technologies and the
need for ireatabilily testing. Because of the strict time sched-
ules and budget constraints placed on the completion of an
Rl/FS, it is crucial for the planning and scoping of trcatabiiiiy
studies to begin as early as possible. As shown in Figure 2,
these efforts should be initiated during the Rl/FS scoping.
Technology prescreening and treatabilily study scoping
will include searching technology literature and ireatability
data bases, consulting wiih technology experts, determin-
ing dam needs, identifying potential ircaiabilily study sources
or contractors, identifying preliminary data quality objec-
tives, and preparing a work assignment. Determination of
the tier or tiers of ireauibiliiy testing to be conducicd will be
based on the technology- and contaminant-specific data needs.
Technology experts arc available within EPA to assist project
managers with technology prescreening and ireatabiliiy
study scoping. (In-house consultation services available to
EPA project managers arc discussed in Subsection 3.3;
additional information is presented in Appendix A.) Early
consultation may save time and money by preventing the
trcaiability testing of inappropriate technologies.
2.2.2 Remedy Screening
Remedy screening, ihe firsi sicp in ihc tiered approach,
provides the gross performance data needed to determine
the potential feasibility of the technology for treating the
contaminants and matrix of concern. Remedy-screening
instability studies may not be necessary when ihc litera-
ture contains adequate data for an assessment of the feasi-
bility of a technology. The results of a remedy-screening
study are used to determine whether additional, more-de-
tailed instability testing should be performed al the rem-
edy-selection lier.
Feasibility is determined by assessing how well a technol-
ogy achieves ihe ireatability study's performance goals,
which arc based on available knowledge of the operable
unit's cleanup criteria and arc set prior 10 the study. Typi-
cally, remedy-screening studies arc conducicd under con-
ditions representative of those in the proposed full-scale
system. If a technology cannot achieve the predetermined
performance goals under these conditions, ii should be
screened oui. If all technologies arc rejected, the project
manager should recvaluatc the screening performance goals
to determine if they arc appropriate.
As shown in Figure 2, remedy-screening ireauibiliiy stud-
ies are initiated during the prc-ROD site characterization
and technology screening activities and may continue
through the identification of alternatives. General charac-
teristics of the remedy-screening tier (outlined in Table 1)
are discussed here.
Study Scale
Performed in Ihe laboratory, remedy-screening ircaiabilily
siudies are limited in size and scope to bench-scale tcsis with
off-the-shelf equipment. Investigations of some technologies
may require additional small-scale field tests at the screening tier.
Type of Data Generated
Remedy-screening studies provide qualitative daia for use
in assessing ihc poicntial fcasibilily of a technology for
Table 1. General Comparison of Remedy-Screening, Remedy-Selection, and RD/RA Treatability Studies
Tier
Remedy
screening
Remedy
selection
RD/RA
Study scale
Bench scale
Bench or pilot scale
Pilol or lull scale
(onsite or offsite)
Full scale
(onsite)
Type
of data
generated
Qualitative
Quantitative
Quantitative
Quantitative
No. of
replicates
Single/
duplicate
Duplicate/
triplicate
Duplicate/
triplicate
Duplicate/
triplicate
Process
type
Batch
Batch or
continuous
Batch or
continuous
Batch or
continuous
Waste
stream
volume
Small
Medium
Large
Large
Time
required^
Days
Days/
weeks
Weeks/
months
Weeks/
months
Cost, S
10,000-
50,000
50,000-
100,000
50,000-
250,000
250.000-
1,000,000
Indicates duration of testing only.
-------
Scoping __
~~the ~"~~
Technology
Prescreening
and
Treatability
Study
Scoping
Remedial Investigation/
Feasibility Study
Identification
of Alternatives
Record of
Decision
Remedy
Selection
Remedial Design/
Remedial Action
Site
Characterization
and Technology
Screening
Evaluation
of Alternatives'
REMEDY SCREENING
TREATABILITY
to Determine
Potential Feasibility
REMEDY SELECTION
TREATABILITY
to Develop Performance
and Cost Data
Implementation
of Remedy
RD/RA TREATABILITY
to Develop Detailed Design
and Cost Data and to
Confirm Performance
Figure 2. The role of treatabilily studies in the RI/FS and RD/RA process.
-------
treating a contaminant/matrix combination. No cost or
design information will be generated. The project manager
must determine the overall qualitative data needs based on
the intended use of the information and the availability of
time and funds.
During remedy screening, a single indicator contaminant is
often monitored to determine whether a reduction in toxic-
ily, mobility, or volume is occurring. If a technology
appears to meet or exceed the performance goal for that
contaminant, it is considered potentially feasible and re-
tained for further evaluation. Remedy screening is also
useful for identifying critical parameters for investigation
at the remedy-selection tier.
Number of Replicates
In most cases, little or no test sample replication (single or
duplicate) is required at the screening tier. A less stringent
level of quality assurance/quality control (QA/QC) is suffi-
cient because a technology thai is found to be feasible must
still undergo remedy-selection testing before it is selected
in the ROD.
Process Type/Waste Stream Volume
Screening will generally involve batch tests and the use of
small-volume samples of the waste stream. For example,
remedy screening of an ion exchange process designed to
treat aqueous wastes may require sample volumes on the
order of 500 millilitcrs per run with only three runs through
the test column.
Time/Cost
The duration and cost of remedy screening depend prima-
rily on the type of technology being investigated and the
number of parameters considered. Generally, remedy screen-
ing can be performed in a few days at a cost of between
510,000 and 550,000. This estimate of duration covers the
time spent in the testing laboratory; it does not include
sample analysis or dam validation, as these elements depend
on the analyticaJ laboratory used. Neither docs it include the
time required for study planning and reporting. The cost
estimate docs include all of these elements, however.
The nature of remedy screening (i.e., simple equipment,
small number of test samples and replicates, less-stringent
QA/QC requirements, and minimum reporting requirements)
makes it the least costly and time-consuming of the three
instability study tiers. Cost and time savings arc increased
by limiting sampling and analysis objectives to address
only indicator contaminants thai arc rcprcscniaiivc of the
families of chemicals present and their concentrations.
2.2.3 Remedy-Selection Testing
Remedy selection is the second step in the tiered approach.
A remedy-selection trcatability study is designed to verify
whether a process option can meet the operable unif
cleanup criteria and at what cost. The purpose of this tier is
to generate the critical performance and cost data necessary
for remedy evaluation in the detailed analysis of alterna-
tives during the FS.
After the feasibility of a treatment alternative has been
demonstrated, either through remedy-screening studies or a
literature review, process operating parameters are investi-
gated at the remedy-selection tier. The choice of param-
eters to be studied is based on the goal of achieving the
operable unit's cleanup criteria and other waste-specific
performance goals. Investigation of equipment-specific
parameters should generally be delayed until posi-ROD
RD/RA studies.
Results of remedy-selection trcatability studies also should
allow for estimating the costs associated with full-scale
implementation of the alternative within an accuracy of
+50/-30 percent, as required for the FS.
As shown in Figure 2, remedy-selection trcatabilily studies
are initiated during the prc-ROD site characterization and
technology screening activities and continue through the
evaluation of alternatives. General characteristics of the
remedy-selection tier (outlined in Table 1) arc discussed here.
Study Scale
Remedy-selection trcatability studies are performed in the
laboratory or field with bench-, piloi-, or full-scale equip-
ment. The scale of equipment used is often technology-
specific, and it will also depend on the availability of funds
and time and the data needs. Equipment should be de-
signed to simulate the basic opcraiions of the full-scale
treatment process. Combinations of bench and field testing
arc also possible at this tier.
Type of Data Generated
Remedy-selection studies provide quantitative data for use
in determining whether a technology can meet the operable
unit's cleanup criteria and at what cost. The operational
and performance information resulting from remedy-selec-
tion studies will be used to estimate full-scale treatment
costs and schedules and to assess the technology against the
RI/FS evaluation criteria.
For example, bench-scale remedy-selection studies of some
technologies can provide the dcuiilcd performance data
10
-------
needed to assess the technology againsi the reduction of
toxicity, mobility, or volume criterion. Pilot-scale testing
may identify waste-stream characteristics that could ad-
versely affect the implementability of a technology. Treat-
ment train considerations, such as the need for further
processing of treated waste or treatment residuals, can also
be addressed at this tier.
When planning remedy-selection treatability studies, the
project manager, in consultation with management, musi
determine the overall quantitative data needs for a technol-
ogy based on the intended use of the information and the
availability of lime and funds. Early consultation with
technology experts and vendors is important when deter-
mining data needs for innovative and proprietary technolo-
gies.
Number of Replicates
Remedy-selection treaiability studies require duplicate or
triplicate test sample replication. Because the daui gener-
ated at this tier will be used for remedy selection in the
ROD, moderately to highly stringent levels of QA/QC are
required. A stringent level of QA/QC is needed to increase
the confidence in the decision that the selected remedy can
achieve the cleanup goals for the site.
Process Type/Waste Stream Volume
Remedy-selection treaiability studies may be conducted as
either a batch or a continuous process. Waste-stream sample
volumes should be adequaie to simulate full-scale opera-
lions. For example, the waste-stream volume needed to
perform continuous, bench-scale testing of an ion exchange
treatment process for an aqueous waste may be on the order
of 1 liter per minute for a treatment duration of 8 hours
(which would require approximately 500 liters of waste).
Waste-handling operations, such as pretreatment blending,
also should be designed to simulate those expected for full-
scale treatment.
Time/Cost
The duration and cost of remedy-selection testing depend
primarily on the type of technology being investigated, the
types of analyses being performed, and the level of QA/QC
required. Most bench-scale studies can be performed within
a period of days to weeks. Pilot-scale testing usually
requires a longer period (i.e., weeks to months). This
estimate covers only the actual performance of ihc lest. It
does not include sample analysis'or data validation, as
ihese elements depend on the analytical laboratory used;
nor does it include study planning and reporting. Depend-
ing on its scale and complexity, a remedy-selection
ireaiability siudy can be performed ai a cost of between
550,000 and S250.000, including analytical suppo:;.
The higher cost and longer lime requirements of remedy-
selection treatability testing compared with remedy screen-
ing are directly related lo the need for stringent QA/QC and
the greater number of test samples and replicates to be
analyzed.
2.2.4 RD/RA Testing
Treatability lesling to support RD/RA activities is the final
step in ihe three-iiered approach. The purpose of an RD/
RA treatability study is to generate the detailed design,
cost, and performance data necessary to optimize and imple-
ment the selected remedy. As shown in Figure 2, RD/RA
instability studies are conducted after the ROD has been
signed. These studies arc performed 1) to select among
multiple vendors and processes within a prescribed remedy
(prcqualification), 2) to implement the most appropriate of
the remedies prescribed in a Contingency ROD, and 3) to
support the Agency's detailed design specifications (if pre-
pared) and the design of treatment trains. Most RD/RA
trcatability studies are performed by remediation contrac-
tors and technology vendors. The EPA RPM monitors the
performance of these studies and reviews the results 10
assess their acceptability with regard 10 ihe ROD, RA
goals, and, if applicable, the settlement agreement. Gen-
eral characteristics of the RD/RA tier (outlined in Table 1)
are discussed here.
Study Scale
Most RD/RA ircatabiliiy studies arc performed in the field
with pilot- or full-scale equipment. Some prequalification
treaiabilily studies will be performed in the laboratory;
however, the system should closely approximate the pro-
posed full-scale operations.
Type of Data Generated
Remedial design/remedial action ircatability studies pro-
vide the detailed, quantitative design and cost dam required
to optimize critical parameters and to implement the se-
lected remedy. The following arc issues that may be ad-
dressed with RD/RA study data:
• Full-scale performance
• Treatment train performance
• Materials-handling characteristics
• Process upset and recovery
11
-------
• Side-stream and residuals generation and treatment
• Energy and reageni usage
• Site-specific considerations, such as heavy equipment
access and waste-feed staging space
• Field-screening analytical methods
The parameters investigated at the RD/RA tier may include
feed rates (continuous processes), number of treatment
cycles (batch processes), mixing rates, heating rates, and
other equipment-specific parameters. Remedial design/
remedial action testing also may identify waste-stream char-
acteristics that could adversely affect the implementabilily
of the full-scale system.
When planning RD/RA treauibility studies, the technology
vendor, in consultation with the designer and the lead
agency, must determine the overall quantitative data needs
for a technology based on the intended use of the informa-
tion. Early consultation with vendors is important in the
determination of data needs for proprietary technologies.
Number of Replicates
Remedial design/remedial action trealability studies usu-
ally require duplicate or triplicate test sample replication.
The data generated at this tier arc used to design and
optimize the process; therefore, stringent levels of QA/QC
are required.
In the case of prcqualification trcatability studies, QA/QC
requirements will be determined by the designer. The num-
ber and types of samples to be submitted by vendors will be
outlined in the designer's prequalification announcement.
Process Type/Waste-Siream Volume
Remedial design/remedial action trcatability studies may
be conducted as either a batch or a continuous process,
depending on the operation of the full-scale system. Waste-
stream sample throughput and volume should achieve lev-
els projected for full-scale operations. For example, the
waste-stream sample volume needed to perform continu-
ous, full-scale testing of an ion exchange treatment process
for an aqueous waste may be on the order of 25 liters per
minute for a treatment duration of 16 hours per day for 21
days (which would require more than 500,000 liters of waste).
Time/Cost
Because of the potentially significant mobilization require-
ments associated with any onsite operation, performing
RD/RA trcatabilily studies is significantly more time-con-
suming and costly than pre-ROD studies. The duration and
cost depend primarily on the type of technology being
investigated, the types of analyses being performed, and
the level of QA/QC required. Most RD/RA studies can be
performed within a period of weeks to months. This esti-
mate covers only the actual performance of the test. It docs
not include the time required for mobilization, construc-
tion, shakedown, or demobilization of the unit, as these
procedures are specific to the site and to the technology
being tested; sample analysis or data validation, as these
elements depend on the analytical laboratory used; or study
planning and reporting. Most RD/RA trcatabiliiy studies
can be performed at a cost of between 5250,000 and
51,000,000.
Prequalification treatability testing is an exception to these
time and cost estimates because the tests are performed at
the vendors' cost. Analytical support, however, is usually
provided by the Agency.
2.3 Applying the Tiered Approach
The purpose of a pre-ROD trcaiability investigation is to
generate data needed for a detailed analysis of the alterna-
tives and, ultimately, the selection of a remedial action thai
can achieve the operable unit's cleanup criteria. Pre-ROD
trcatability studies are performed to enable the decision
maker to evaluate all treatment and nontrcatmcni alterna-
tives on an equal basis.
The need for pre-ROD treauibility testing at a Supcrfund
site is a risk-management decision in which the cost and
lime required to conduct ircaiability studies arc weighed
against the risks inherent in the selection of a remedial
technology. Factors in this decision are specific to the
waste matrix, waste contaminants, and treatment technol-
ogy. Determining whether pre-ROD trcatabilily studies
should be conducted may also depend on such nontechnical
factors as State and community acceptance of an alterna-
tive; time constraints on the completion of the Rl/FS and
the ROD; and the discovery of new operable unit-, wasic-,
or technology-based data that may have an impact on treat-
ment performance.
Of the management decision factors listed, schedule con-
straints may be of the most consequence. The performance
of pre-ROD trcatability studies thai were planned and sched-
uled early (i.e., during the scoping of the RI/FS) generally
should not delay the ROD. In some instances, however, the
need for treatability studies may conflict with RI/FS and
ROD schedule commitments. For example, if an innova-
tive technology is being considered as pan of an altcrna-
12
-------
live, significant gaps in the technical literature may lengthen
the lime required to plan and perform a thorough trcaiability
investigation. When the potential benefits of the inno-
vative technology are known, pursuing the treatability study
at the expense of ROD scheduling goals may be appropri-
ate. The EPA's Guidance for Increasing the Application of
Innovative Treatment Technologies for Contaminated Soil
and Ground Water (EPA 199la) and il& cover memoran-
dum indicate the Agency's willingness to adjust program
goals and commitments, when appropriate, to achieve bet-
ter cleanup solutions through innovative treatment technol-
ogy development.
The flow diagram in Figure 3 traces the stepwisc data
reviews and management decisions that occur in the tiered
approach. Site characterization and technology
prescreening/trcatabiliiy study scoping initiate the process.
Technologies that are determined to be potentially appli-
cable (based on effectiveness, implemcntability, and cost)
are retained as alternatives; all others arc screened out. The
decision to conduct a ircatability study on an alternative is
based on the availability of technology-specific ircatabiliiy
information and on inputs from management. If a treat-
ment technology is well demonstrated for the particular
contaminants/matrix and sufficient information exists to
permit ils evaluation against the nine evaluation criteria in
the detailed analysis of alternatives, a pre-ROD treatability
study is not required.
If significant questions remain about the feasibility of a
technology for remediating an operable unit, a remedy-
screening treatability study should be performed. Innova-
tive technologies or wastes that have not been extensively
investigated should almost always be subjected to trcaiability
testing at this tier. If a technology has been shown to be
effective at treating the contaminants/matrix of concern but
insufficient information exists for detailed analysis, the
remedy-screening tier may be bypassed in favor of a rem-
edy-selection treatability study. If a remedy-selection study
indicates that a technology can meet the cleanup criteria, a
detailed analysis of in is alternative should then be per-
formed. If ihe altcmaiivc is selected in ihe ROD, a post-
ROD RD/RA ircaiability study may be required to design
and optimize ihe full-scale system, to obtain detailed cost
data, and to confirm performance.
2.4 Treatability Study Test Objectives
Each tier of ircatabiliiy testing is defined by its particular
purpose: remedy screening, to determine potential feasibil-
ity; remedy selection, to develop performance and cost
data; and RD/RA, to develop detailed design and cost daia
and to confirm full-scale performance. For achievement of
these purposes, the planning and design of trcatabiliiy stud-
ies must reflect specific, predetermined test objectives.
Depending on the tier of testing, test objecii vcs may call for
making qualitative engineering assessments, achieving quan-
titative performance goals, or both. Because test objcctives
are technology-, matrix-, and contaminant-specific, setting
universal objectives for each tier of testing is impossible.
Qualitative assessments of performance arc often appropri-
ate at the remedy-screening tier. Simply demonstrating a
reduction in contaminant concentration, for example, may
be sufficient to confirm the potential feasibility of using an
innovative treatment technology. For other technologies, a
quantitative performance goal such as 50 percent reduction
in contaminant mobility might indicate the potential to
achieve greater reduction through process refinements and
thus confirm the feasibility of a process option and justify
additional testing at the remedy-selection tier.
Test objectives at the remedy-selection tier will include
achieving quantitative performance goals based on the an-
ticipated cleanup criteria to be established in the ROD. For
example, if the cleanup criterion for a contaminant in the
soil at a site is 1 ppm, the performance goal for a remedy-
selection treatability study might also be 1 ppm. If no
cleanup criteria have been established for the site, a 90
percent reduction in the contaminant concentrations will
generally be an appropriate performance goal. This level
of performance is in agreement with EPA's guideline es-
tablished in the 1990 revised NCP, which states that ". . .
treatment as part of CERCLA remedies should generally
achieve reductions of 90 to 99 percent in the concentration
or mobility of individual contaminants of concern, although
there will be situations where reductions outside the 90 to
99 percent range that achieve health-based or other site-
specific remediation goals (corresponding to greater or
lesser reductions) will be appropriate" (55 FR 8721). Ad-
ditional guidelines upon which a project manager should
base remedy-selection performance goals arc as follows:
• Protection of human health and the environment
• Compliance with ARARs
• Attainment of contaminant levels acceptable for waste
dclisting
• Attainment of contaminant levels accepted by the State
or Region at other sites with similar waste characteristics
Remedy-selection ircaiability studies will generally have
additional prc-ROD test objectives designed to provide the
specific cost and engineering information necessary for a
detailed analysis of the alternative. Cost data should be
13
-------
SITE
CM»R»CTEfW«ON
TECHNOIOGY PRESCREENNCV
TBEATMUFTY STUDY SCOP NG
MANAGEMENT DECISION FACTORS:
• Stale and Community Acceptance
• Schedule Constraints
• Additional Data
REMEDY-SCREENING
TREAWBimr
STUDIES
REMEDY-SELECTION
IflEATABILtTY
STUDIES
RD/RA
THEATABILmr
STUDIES
Figure 3. Flow diagram of the tiered approach.
-------
sufficiently detailed to allow for the development of cost
estimates with an accuracy of +51' to -30 percent.
Post-ROD test objectives depend on the nature of the
instability study. If a study is conducted to prcqualify
vendors, performance goals will be equivalent to the cleanup
criteria defined in the ROD. Treatabilily studies conducted
to select the most appropriate technology among those in a
Contingency ROD will also have performance goals equiva-
lent to the cleanup criteria. Additional test objectives may
include investigation of materials-handling methods, con-
firmation of field-screening analytical techniques, and gen-
eration of detailed cost data. If an RD/RA instability study
is required to support the detailed design specifications, the
designer will be responsible for defining the test objectives
and performance goals. Test objectives will be focused on
obtaining specific design daia, optimising performance,
and minimizing cost. Treatment train issues such as unit
sizing, materials handling, and systems integration can also
be addressed through specific test objectives. A trcatabiliiy
study of an entire train can provide data to confirm compli-
ance with ARARs and the cleanup criteria outlined in the
ROD.
2.5 Special Issues
2.5.7 Innovative Treatment
Technologies
One of the advantages of treatability testing is that it per-
mits the collection of performance data on innovative treat-
ment technologies. These newly developed technologies
often lack sufficient full-scale application to be routinely
considered for site remediation. Nevertheless, Guidance
for Increasing the Application of Innovative Treatment
Technologies for Contaminated Soil and Ground Water
(EPA 199la) states:
"Innovative treatment technologies are to be rou-
tinely considered as an option in feasibility stud-
ies for remedial sites and engineering evaluations
for removals in the Superfund program, where
treatment is appropriate commensurate with the
National Contingency Plan (NCP) expectations... .
Innovative technologies considered in the remedy
selection process for Superfund, RCRA, and UST
should not be eliminated solely on the grounds
that an absence of full-scale experience or
treatability study data makes their operational
performance and cost less certain than other forms
of remediation.
"When assessing innovative technologies, it is
impurtant to fully account for their benefits. De-
spite the fact that their costs may be greater than
conventional options, innovative technologies may
be found to be cost-effective, after accounting for
such factors as increased protection, superior per-
formance, and greater community acceptance. In
addition, experience gained from the application
of these solutions will help realize their potential
benefits at other sites with similar contaminants."
Example 1 illustrates how instability studies can be used to
investigate innovative and conventional technologies con-
currently on a single waste stream. Three innovative treat-
ment technologies-thermal dcsorption, solvent extraction,
and biorcmediauon-arc investigated at various tiers. Deci-
sions on testing are based on existing data in the literature
and on prior ircaiubility study results. Solidification/suibi-
li/ation, a conventional option, is also tested because its
performance for the particular waste stream was not estab-
lished in the literature. This example reflects how trcatability
studies can be designed and tailored by the project manager
to provide specific pieces of information required for rem-
edy selection.
2.5.2 Treatment Trains
Treatment of a waste stream often results in residuals that
require further treatment to reduce toxicily, mobility, or
volume. Treatment technologies operated in scries (treat-
ment trains) can be used to provide complete treatment of a
waste stream and any resulting residuals.
Treatment-train requirements for a waste stream may be
evaluated by applying the tiered approach. Example 2
outlines a remedy-selection trcatabiliiy study of a treatment
train consisting of low-icmpcraiurc volatilization followed
by chemical treatment and solidification. The literature
contains enough data concerning the individual unit opera-
tions to indicate that they arc appropriate technologies for
the specific contaminants. Treauibilily testing of these unit
operations as a treatment train, however, is necessary to
evaluate the most effective combination of operating pa-
rameters for treating the matrix.
2.5.3 In Situ Treatment Technologies
Testing of in situ treatment technologies during ihc RI/FS
may entail remedy screening, bench-scale remedy-selec-
tion testing, and pilot-scale remedy-selection testing in the
Held. Remedy screening of in situ treatment technologies
is conducted in the laboratory to determine process feasi-
bility. Bench-scale testing is generally conducted in soil
columns designed to simulate the subsurface environment.
Field testing, however, is important for an adequate cvalua-
15
-------
EXAMPLE 1. TREATABILITY STUDIES OF MULTIPLE TECHNOLOGIES
Old Petroleum Refinery Site
Background
An old petroleum refinery site contained oily sludges and contaminated soils. The primary contami-
nants of concern were polynuclear aromatic hydrocarbons (PAHs), mainly benzo(a)pyrene. The
literature survey identified five potentially applicable technologies for treating the hydrocarbon
wastes: 1) incineration, 2) stabilization/solidification, 3) thermal desorption, 4) solvent extraction,
and 5) bioremediation.
The literature survey also produced a significant amount of performance data for incineration and
bioremediation. Because these data indicated that both technologies were valid for the types of
wastes and contaminants of concern at the site, neither incineration nor bioremedialion was evalu-
ated at the remedy-screening tier.
Conversely, little data w^re found on thermal desorption, and the available performance data for
solvent extraction and stabilization/solidification were inconclusive for hydrocarbon wastes. There-
fore, these three technologies were evaluated at the remedy-screening tier to determine their
feasibility for treatment of the site's wastes.
Remedy Screening
Samples of worst-case soils and sludges (most highly contaminated with PAHs) were collected for
treatability studies of each technology. A performance goal of 90 percent reduction in the indicator
contaminant benzo(a)pyrene was set.
Thermal desorption was evaluated at three temperatures. Solvent extraction was evaluated by
using three solvents at two solution concentrations. Stabilization/solidification was evaluated by
using organophilic clays at three mix ratios with 28-day curing. Benzo(a)pyrene concentration in
duplicate samples of the untreated soil was determined by total waste analysis (EPA SW-846
Method 8270). Duplicate samples of the treated material from thermal desorption, solvent extrac-
tion, and stabilization/solidification (after sonication of the solidified monolith) were then analyzed
for benzo(a)pyrene by Ihe same method.
The results of the remedy screening showed that, of the three technologies, thermal desorption
achieved the. highest percentage removal of the indicator contaminant (greater than 95 percent)
Solvent extraction showed a 90 percent removal efficiency. Stabilization/solidification, however,
fixed only 50 percent of the contaminant. Thermal desorption and solvent extraction were thus
retained for further analysis because both technologies achieved the screening performance goal.
Remedy-Selection Tenting
Quantitative performance, implementability, and cost issues still remained unanswered after the
remedy screening. Also, information from the literature on biodegradation rates and mechanisms
for benzp(a)pyrene (the principal PAH of concern) was inconclusive. In addition, the anticipated
cleanup criterion for benzo(a)pyrene in soils was very low (250 ppb). Therefore, thermal desorp-
tion, solvent extraction, and bioremediation were examined in bench-scale, remedy-selection
testing. Performance goals were set at 250 ppb benzo(a)pyrene with a 95 percent data confidence
level. Waste samples representing average and worst-case scenarios were tested, triplicate test
samples were collected and analyzed, and several process variables were evaluated. After 6
months of testing, only low-temperature thermal treatment was found to meet the low cleanup levels
required for benzo(a)pyrene.
Although thermal desorption was found to meet the cleanup requirements in bench-scale testing,
this technology had not been previously demonstrated at full scale for similar contaminants and
waste. Therefore, cost and design issues had to be addressed as pan of the detailed analysis of
alternatives. The RPM decided to conduct pilot-scale testing on thermal desorption and to compare
the costs of constructing and operating the unit with those for incineration.
16
-------
EXAMPLE 2. TREATABILITY STUDIES FOR TREATMENT TRAINS
Former Chemical Manufacturing Company
Background
At a former chemical manufacturing company and current Supertund site, the contaminants of
concern in the soils were dichloromethane, tetrachloroethene, benzene, polynuclear aromatic hydro-
carbons (PAHs), cyanide, and arsenic. The cleanup criterion for each of these compounds had been
identified. Both onsite treatment and offsite incineration were being considered as options for site
remediation.
Remedy-Selection Testing
Remedy-selection testing of a treatment train to treat the contaminated soils on site was designed to
include the following unit operations: 1) thermal desprption, 2) chemical treatment, and 3) stabiliza-
tion/solidification. A schematic of the treatment train is presented below.
CONTAMINANTS OF CONCERN
ORGANICS
ARSENIC
STABILIZATION/
SOLIDIFICATION
Schematic Representation of the Treatment Train
Bench-scale treatability testing of the treatment train was designed to meet the following three
objectives:
• Objective 1 - Provide performance confirmation of the operation of the thermal desorptioh unit for
removal of volatile and semivolatile organics. Determine the minimum operating conditions
(temperature, residence time) necessary to achieve the site cleanup criteria. Determine the need
for subsequent treatment units (chemical treatment, solidification).
• Objective 2 - Provide performance confirmation of the operation of the chemical treatment unit for
destruction of cyanide. Determine the preferred reagent and dosage necessary to achieve the
site cleanup criteria.
• Objective 3 - Provide performance confirmation of the operation of the stabilization/solidification
unit for immobilization of arsenic. Determine the preferred binder and dosage necessary to
achieve the site cleanup criteria.
Prior to initiating any treatability tests, the test plan called for the soil to be characterized for the
following physical and chemical parameters:
• Moisture content
• Soil bulk density
• Grain size distribution
• Volatile and semivolatile organics
• Cyanide
• Arsenic (total and TCLP)
The remedy-selection testing consisted of the following three subtasks:
1) Perform bench-scale tests of thermal desorption at two temperatures (300 and 550°C) and three
residence times (5,15, and 30 minutes) to determine the efficacy of the unit for removal of
17
-------
Example 2 (continued)
organics. Analyze the treated soil lor the pollutants of concern (organics, cyanide, and arsenic).
If cyanide is present in the soil residue at concentrations exceeding the cleanup criterion, con-
tinue with Subtask 2. Similarly, if arsenic is present, continue with Subtask 3. (This subtask
addresses Objective 1.)
2) Perform bench-scale tests on the soil residue from the thermal desorption unit to investigate the
effectiveness of hydrogen peroxide and hypochlorite for treatment of cyanide as a function of pH,
the strength of solution, and the reagent-to-soil ratio. Analyze the treated soil for cyanide. (This
subtask addresses Objective 2.)
3) Perform bench-scale tests of stabilization/solidification to immobilize arsenic in the soil residue
from'chemical treatment (if cyanide was present) or thermal desorption (if cyanide was not
present) using three binders (Portland cement, lime/fly ash, and fly ash/kiln dust) at two binder-to-
soil ratios (0.20 and 0.50). Determine the unconfined compressive strength of the solid monolith.
Extract the crushed solid in accordance with the toxicity characteristic leaching procedure and
analyze the leachate for arsenic. (This subtask addresses Objective 3.)
Data from the remedy-selection treatability tests were used 1) to determine if the proposed treatment
train could achieve the test objective of reducing all contaminant concentrations to the site cleanup
criteria, and 2) to provide a preliminary basis for estimating the costs of full-scale remediation.
lion of in situ treatment. Because of the unique difficulties
associated with simulating in situ conditions and monitor-
ing the effectiveness of in situ treatment in the laboratory,
field testing often may be the only way to obtain the critical
information needed for the detailed analysis of alternatives
during the FS. Example 3 demonstrates how the tiered
approach may be applied to evaluate in situ soil Hushing.
2.5.4 Generic Vs. Vendor Treatability
Studies
When planning a ircatability study, the project manager
musi determine whether results from treatability tests in
which widely available chemicals and processes are used
("generic" studies) will be as useful as vendor-conducted
tests involving the use of proprietary chemical reagents and
treatment systems ("vendor" studies).
Because generic trcatabiliiy studies eliminate the need for
establishing contracts and schedules with a specific vendor,
they can often be performed quickly and inexpensively;
however, they may not always provide an adequate evalua-
tion of a technology. For example, a generic trcatability
study may fail to meet site cleanup goals that could have
been achieved by an experienced technology vendor using
proprietary processes and equipment developed through
years of research.
Generally, remedy-screening trcatabiliiy studies can be per-
formed generically because quantitative performance data
are not required. Vendor-specific equipment or experience
are often required, however, at the remedy-selection tier to
assure the generation of high-quality quantitative data and
the best performance of the technology. Remedial design/
remedial action trcalability studies should generally be per-
formed in consultation with technology vendors. Tables 2
and 3 were adapted from tables developed by personnel ai
ihc U.S. EPA's Risk Rcduciion Engineering Laboratory
(RREL) to provide general technology-specific guidance
on this issue (dePcrcin, Bates, and Smiih 1991). Informa-
tion in these tables should not be used without consider-
ation being given to site-specific contaminant and matrix
ircaiabiliiy data.
Under 48 CFR Scciion 1536.209 of ihe Federal Acquisiiion
Regulations, subcontractors performing ircaiability sludics
in support of remedy scleciion or remedy design arc not
prohibiicd from being awarded a coniract on ihc construc-
lion of ihc remedy (55 FR 49283). For prime contractors
performing ircaiability sludics, however, approval by ihc
Responsible Associate Director in the EPA Procurement
and Contracts Management Division may be necessary
before they can be awarded the consiruciion coniract. In
reviewing requests for approval, EPA will lake into ac-
couni its policy of promoiing the use of innovative tech-
nologies in the Supcrfund program.
2.5.5 PRP-led Pre-ROD Treatability
Studies
Prc-ROD ircaiabiliiy sludics may be conducicd by potcn-
lially responsible panics wiih EPA oversight to evaluate
PRP-proposcd alternatives at cnforccmcnt-lcd sites. The
steps involved in a PRP-lcd study include performing a
18
-------
EXAMPLE 3. TREATABILITY STUDIES FOR IN SITU TREATMENT TECHNOLOGIES
In Situ Soil Flushing
Background
An estimated 80,000 cubic meters of soil contaminated with chlorinated phenols, semivolatile organ-
ics, sultur-containing compounds, and lead at an industrial facility requires corrective action. In situ
soil flushing has been proposed as an alternative treatment technology. A two-tiered treatability study
has been designed to evaluate its effectiveness.
Remedy Screening
Remedy screening will be performed to evaluate the effectiveness of various flushing reagents for
enhancing the removal of the contaminants. A performance objective of 90 percent or greater
reduction was set for evaluation of flushing reagent feasibility. Any reagent that achieves this level of
contaminant reduction for each target contaminant will be evaluated at the remedy-selection tier. All
others will be screened out. (Analyses of all samples for all site-specific contaminants will not be
economically feasible; therefore, target compounds, each representative of a class of compounds
present at the site, will be identified.)
The following general testing procedure will be used:
1) Analyze untreated soil samples for target compounds.
2) Place a known mass of soil in a small glass bottle. Add a measured volume of flushing reagent.
Shake for a set period of hours. Centrifuge the mixture.
3) Analyze the supernatant liquid phase for target contaminants.
4) Analyze the treated soil phase for target contaminants.
Remedy-Selection Testing
Bench Scale
All flushing reagents identified as feasible during the remedy-screening treatability study will be
evaluated in a bench-scale column test. The performance objective of this tier is to achieve contami-
nant reduction levels equal to the anticipated site cleanup criteria.
The following general testing procedure will be used:
1) Analyze untreated soil samples for target compounds.
2) Pack a large glass column with untreated soil to approximate the actual density of soil in the
contaminated area. Introduce the soil-flushing solution into the top of the column.
3) Collect the column leachate at regular intervals (e.g., daily) and analyze for target contaminants.
4) Terminate the column test when the contaminant concentrations in the leachate remain the same
for three consecutive leaching periods. Remove representative samples of the treated soil from
the glass column and analyze them for target contaminants.
All flushing reagents that reduce the target contaminant concentrations in the soil to the site cleanup
levels will be evaluated in the field.
Pilot Scale
The twofold purpose of this field pilot-scale treatability study is to evaluate the hydraulics of the
treatment process under site conditions and to verify reagent performance under site conditions. The
field test will yield site-specific flow, injection, and capture rates for the flushing system. These rates
must be established to quantify the total time necessary for site-wide treatment and to estimate full-
scale treatment costs. These and other data will be used in the detailed analysis of alternatives.
The field treatability study will involve the following tasks:
1) Prepare a treatment cell. Install an interception trench.
2) Install the irrigation and soil-flushing system.
3) Collect the cell leachate at regular intervals and analyze for all contaminants of interest.
4) Terminate the field test when the target contaminant concentrations in the leachate remain the
same for three consecutive leaching periods. Remove representative samples of the treated soil
from the cell and analyze them for all contaminants of interest.
19
-------
Table 2. Aqueous Field Treatability Studies:
Generic Versus Vendor Processes8
Treatment technology
Physical
Oil/water separation
Sedimentation
Filtration
Solvent extraction
Distillation
Air/steam stripping
Carbon adsorption
Ion exchange
Reverse osmosis
Ultra filtration
Chemical
Neutralization
Precipitation
Oxidation
Reduction
Dehalogenation
Thermal
Incineration
Biological
Suspended growth
systems
Aerobic
Anaerobic
Fixed growth systems
Aerobic
Anaerobic
Constructed wetlands
Pact
In situ biological
Remedy
screening
NA
NA
NA
G
G
G
G
G
G
G
NA
G
G
G
G
G
G
G
G
G
G
G
NA
Remedy
selection
G
G
G
G/V
G
G
G
G
G/V
V
G
G
G
G
G/V
G/V
G
G
G/V
G/V
G
G/V
G
RD/RA
G
G
G
G/V
G/V
G/V
G
G/V
V
V
G
G
G
G
V
V
G
G/V
G/V
G/V
G
V
V
aG = Generic studies appropriate.
V = Vendor studies appropriate.
G'V = Generic ana vendor studies appropriate.
NA = Not applicable at this tier.
literature search, submitting the Technical Memorandum
identifying candidate technologies, designing the study,
preparing the Project Plans (Work Plan, Sampling and
Analysis Plan, and Health and Safety Plan), performing the
lest, analyzing the data, and preparing a final report on the
results.
During the study, the EPA project manager will provide
oversight and assistance. The EPA's Guidance on Over-
sight of Potentially Responsible Party Remedial Investiga-
tions and Feasibility Studies (EPA I991b) recommends
thai the EPA project manager and the oversight assistant
perform the following activities to oversee PRPs:
• Provide the PRPs with relevant guidance documents
and sources of other technical information (Appendix
A presents sources of ircatability information).
• Review and approve the Technical Memorandum pre-
pared by Ihc PRP that identifies candidate treatment
technologies and describes the literature search.
• Meet with the oversight assistant, the Technical Sup-
port Team (TST), and representatives from ORD to
review the list of candidate technologies. Innovative
treatment technologies should be adequately repre-
sented. Decisions on the need for ircatabiliiy studies
should be made for each technology.
• Review and approve the PRP's schedule of trcatability
activities.
Table 3. Soils/Sludges Field Treatability Studies:
Generic Versus Vendor Processes"
Treatment technology
Physical
Oil/water separation
Sedimentation
Filtration
Solvent extraction
Soil washing
Vacuum extraction
Distillation
Air/steam stripping
Thermal stripping
Carbon adsorption
Ion exchange
Chemical
Neutralization
Precipitation
UV photolysis
Ozonation
Oxidation
Reduction
Dehalogenation
Thermal
Incineration
Biological
In situ treatment
Composting
Stabilization
Pozzolanic tor
inorganics
Pozzolanic for organics
Asphalt
Polymerization
Vitrification
Material handling
Screening
Conveying
Remedy
screening
G
G
G
G/V
G
G
G
G
G
G
G/V
G
G
G
G
G
G
G/V
G
G
G/V
G
V
G
V
G/V
NA
NA
Remedy
selection
G
G
G
V
G/V
V
G
G/V
V
G/V
V
G
G/V
V
G/V
V
V
V
G/V
G
G'V
G/V
V
V
V
V
G
G
RD/RA
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
G/V
V
V
V
V
V
G/V
G/V
= Generic studies appropriate.
V = Vendor studies appropriate.
G/V = Generic and vendor studies appropriate.
NA - Not applicable at this tier.
20
-------
• Revise and amend the original PRP Pro.icci Plans to
address the treatability study work to be performed.
• Verify the qualifications of all personnel involved in
the test, including the PRP, the PRP's contractor, and
the analytical laboratory. In addition, the EPA project
manager should verify that the PRP laboratory proto-
cols conform to EPA standards.
• Verify the test objectives and performance goals of
each study.
• Conduct a site visit during the initial stages of a study.
• Collect and analyze split samples before and after
treatment.
• Review and validate the data generated by each study.
• Monitor compliance with ARARs.
• Review and approve the draft PRP Treatability Study
Evaluation Report whh input and comments from the
TST, ORD, other suppon staff, and the Stale. (The
report should be prepared in the standard formal pre-
sented in Subsection 3.12.)
• Continually update the Administrative Record File and
cost recovery documentation.
ConductorPRP-led treatability studies will be based on the
language of the Administrative Order on Consent (AOC)
and the Statement of Work (SOW). The model Adminis-
trative Order on Consent for Remedial Investigation/Fea-
sibility Study (EPA 1991c) contains standard language for
requiring PRPs to conduct treatabiliiy studies. The Model
Statement of Work for a Remedial Investigation and Feasi-
bility Study Conducted by Potentially Responsible Parties
(EPA 1989c) provides standard language for requiring PRPs
to perform treatability studies in accordance with the Rl/FS
guidance. (Note: The Model SOW docs not yet incorpo-
rate the treatabiliiy study terminology and guidance pre-
sented in this document. Until the Model SOW is updated,
every effort should be made to require PRPs to conduct
instability studies in accordance with this guidance.)
2.5.6 Treatability Study Funding
The planning process for ircaiabilisy sludies should begin
during the budget cycle in ihc year prior 10 ihc planned
performance. The poiential need for and scope of ircauibility
sludies should be idcniificd and their costs estimated 10
ensure that adequate resources will be available. This
informaiion will be used to prepare the Region's Supcrfund
Comprehensive Accomplishments Plan (SCAP).
Federally funded trcauibility studies performed in support
of the RI/FS or the RD/RA are funded as a line item in the
Region's "Other Remedial Account" Should treauibility
study funding requirements exceed planned allocations (be-
cause of the cosi of Ihe sludies or the need for studies that
were not planned for in ihc SCAP), ihc SCAP should be
updated to reflect the necessary additional funding.
Funding for ircatabilily studies is currently separate from
Rl/FS funding and is not included in the RI/FS target cost
of 5750,000. The Agency is considering a revision of ihis
procedure, based on the need lo fund direct site work through
a Siie-Spccific Allowance. This will facilitate efficient
iracking of direct site costs.
21
-------
SECTION 3
PROTOCOL FOR CONDUCTING TREATABILITY STUDIES
3.1 Introduction
Trcatability studies should be performed in a systematic
fashion to ensure that the data generated can support rem-
edy selection and implementation. This section describes a
general protocol for conducting trcalability studies that
EPA project managers, PRPs, and contractors should fol-
low. The protocol includes:
• Establishing data quality objectives
• Identifying sources for treatability studies
• Issuing the Work Assignment
• Preparing the Work Plan
• Preparing the Sampling and Analysis Plan
• Preparing the Health and Safety Plan
• Conducting community relations activities
• Complying with regulatory requirement
• Executing the study
• Analyzing and interpreting the data
• Reporting the results
These elements arc described in detail in the remaining
subsections. General information applicable 10 all
treatabilily studies is presented first, followed by informa-
tion specific to remedy screening, remedy-selection test-
ing, and RD/RA testing.
Pre-ROD treatability studies for a particular site will often
entail multiple tiers of testing, as described earlier in Sub-
section 2.3. Duplication of effort can be avoided by recog-
nizing this possibility in the early planning stages of the
project. The Work Assignment, Work Plan, and other
supporting documents should include all expected activities.
Generally, a single contractor should be retained to ensure
continuity of the project as it moves from one tier to another.
3.2 Establishing Data Quality
Objectives
Data quality objectives (DQOs) arc qualitative and quanti-
tative statements that specify the quality of the data required
to support decisions concerning remedy selection and imple-
mentation. The end use of the ircatabilily study data to be
collected will determine the appropriate DQOs. At all tiers of
ircatabilily lesiing, the establishment of DQOs will help to
ensure that the data collected arc of sufficient quality 10
substantiate ihc decision. Established DQOs arc incorporated
into the Work Plan, the study design, and the Sampling and
Analysis Plan (SAP). Because trcalability icsting is used to
help select and implement a site remedy, establishing DQOs
is a critical initial step in the planning of ircatabilily studies.
The quality and quantity of trcatability daia required for a
study should correspond to the significance and ramifica-
tions of Ihc decisions that will be based on these data.
Limited QA/QC is generally required for remedy-screen-
ing data used to decide whether a treatment process is
potentially feasible and warrants further consideration. More
rigorous QA/QC is required for remedy-selection testing
data used 10 determine whether a technology can meet the
expected cleanup criteria or to compare the costs of several
treatment alternatives, as ihcsc data have a greater impact
on ihc decisions required for icchnology sclcciion. Rigor-
ous QA/QC is also required for RD/RA lesiing when quan-
litativc performance, design, and cost daia will he used in
ihc implementation of the selected remedy.
3.2.1 General
The guidance document Data Quality Objectives for Reme-
dial Response Activities (EPA 1987a) defines the framc-
23
-------
work and process by which DQOs are developed. This
document (hereinafter referred to as the DQO guidance)
focuses on site investigations during the RI/FS; however,
the same framework and process may be applied to DQO
development for treatability studies. The DQO guidance
describes a process that includes the following three stages:
1) identification of decision types and study objectives, 2)
identification of data uses/needs, and 3) design of the data-
collection program. The three stages of DQO development
summarized in Table 4 can be applied to each of the three
tiers of testing. The stages provide a systematic process for
development of-the DQOs for treatability studies.
Stage 1
The type and magnitude of the decisions to be made are
determined in Stage 1. Tasks include identifying the data
users and coordinating their efforts for the establishment of
the DQOs, evaluating existing data, developing a concep-
tual model, and specifying the test objectives (including
performance goals) of the treatability study. Stage 1 efforts
should result in the specification of the decision-making
process and the identification of any new data needed and
why. Stage 1 of the DQO process corresponds to technol-
ogy prescreening and treatability study scoping as described
in Subsection 2.2.1.
The data users will be those who rely on treatability results
to support their decisions. They may include the RPM, the
OSC, the PRP project manager, technical specialists, the
State, enforcement personnel, U.S. Army Corps of Engi-
neers, and others. Project review and audit personnel should
be involved to help ensure the integrity of the QA progr. m
and compliance with program policy.
Stage 1 also includes a detailed evaluation of available
information. Useful information may include site charac-
terization data, technology-specific information, and previ-
ous treatability study data. Several factors should be con-
sidered in an evaluation of the quality of these data and
their relevance to the DQO establishment process, inclu<:-
ing the age of the data, the analytical methods used, the
detection limits of those methods, and the QA/QC proce-
dures applied.
A conceptual model of the site and site conditions should
be developed and included in Stage 1. A model may
already have been developed for the site; if so, it should be
adopted for use in the ircatabiliiy study DQO development
process.
Test objectives for the trcatability study are determined in
Stage 1. Identifying these objectives also entails identify-
ing the problems to be solved (i.e., whether the study is
needed to determine the potential feasibility of the technol-
ogy or to confirm the attainment of a treatment standard).
Test objectives will include achieving quantitative perfor-
mance goals and collecting data to support qualitative engi-
neering assessments and cost estimates.
Stage 2
During Stage 2, the data required to meet the test objectives
specified in Stage 1 arc determined, and the criteria for
Table 4. Summary of Three-Stage DQO Development Process
Stage 1
Identify data users.
Consult appropriate data bases for relevant information.
Develop a conceptual model of the site.
Identify the treatability study test objectives and performance goals.
Stage 2
Identify data uses.
Identify data types.
Identify data quality needs.
Identify data quantity needs.
Evaluate sampling and analysis options.
Review precision, accuracy, representativeness, completeness, and comparability
parameters.
Stage 3
Determine DQOs; select methods for obtaining data of acceptable quality and quantity.
Incorporate DQOs into the Work Plan and the SAP.
24
-------
determining daia adequacy are stipulated. Data must be of
sufficient quality to determine whether the lest objectives
have been met.
Data types are identified by broad categories such as envi-
ronmental media samples or source samples. Specifying
data type by medium helps to identify overlapping data
needs and analytical efforts.
Data quality and quantity are defined in Stage 2. The
EPA's Quality Assurance Procedures for RREL (EPA
1989d) establish four quality assurance categories for use
in research and development projects. Categories IV, III,
and II are applicable to trcauibility studies. In general, QA
Category IV applies to remedy-screening trcatabilily stud-
ies, and QA Categories III and II apply to botli remedy-
selection and RD/RA ircauibility studies. In determining
the appropriate QA category, the decision maker must
consider the intended use of the data and the risks associ-
ated with selecting an ineffective remedy based on the
quality and quantity of the trcatability data collected.
When the data quality needs for a project have been de-
fined, confidence limits can be established for ihe data to be
generated. Specific confidence limits have not been estab-
lished for each treatability study tier. Rather, the intended
use of the data and the limitations and costs of various
analytical methods will assist the decision maker in defin-
ing appropriate confidence limits for the tier of testing
being planned. Sampling and analysis options are re-
viewed in Stage 2 of the DQO development process. Issues
to be considered during the review process include the data
uses; duu types; data quality needs; data quantity needs;
precision, accuracy, representativeness, completeness, and
comparability (PARCC) parameters (Table 5); analytical
costs; and the time required for analysis.
The PARCC parameters arc defined by the intended use of
the data and are indicative of data quality. As the data
quality and quantity needs increase, the PARCC parameter
goals must rise. It is not practical to set universal PARCC
goals for treatability testing because of the variability in
sites, technologies, and contaminants.
Stage 3
Methods for obtaining data of acceptable quality and quan-
tity are chosen and incorporated into the project Work Plan
and SAP during Stage 3. The purpose of. Stage 3 is to
assemble the data collection components into a compre-
hensive data collection program. As data quality needs
increase, the need for detailed goals and documentation
components in the collection program will increase.
3.2.2 Remedy Screening
The DQOs established for remedy screening arc usually
stated in qualitative terms. Remedy screening provides a
qualitative engineering assessment of the potential feasi-
bility of a technology (i.e., go/no go). Therefore, QA
Category IV usually provides data of sufficient quality for
remedy screening. According to Quality Assurance Proce-
dures for RREL, QA Category IV is designed to support
basic research that may change direction several times in
Table 5. PARCC Parameters
Precision
Accuracy
Representativeness
Completeness
Comparability
A quantitative measure of the variability of a group ot measurements, normally
stated in terms of standard deviation, range, or relative percent difference.
Precision is determined from analytical laboratory replicates (split samples) and
test replicates (collocated samples).
A quantitative measure of the bias in a measurement system, normally stated
in terms of percent recovery. Accuracy is determined by QC samples and
matrix spikes with known concentrations.
A qualitative statement regarding the degree to which data accurately and
precisely represent a population or condition. Representativeness is addressed
by ensuring that sampling locations are selected properly and that a sufficient
number of samples are collected.
The percentage of the measurements that are judged to be valid. Regardless
of the use of the data, a sufficient amount of the data generated should be
valid.
A qualitative statement regarding the confidence with which one data set can
be compared with another. Comparability is achieved through the use of
standard techniques to collect and analyze samples and to report results.
25
-------
the course of testing. The PARCC requirements arc therefore
broadly defined in this category to permit flexibility during
the actual testing. Confidence limits established for data
derived from remedy screening are typically wide, in keeping
with the characteristics of this tier (i.e., low cost, quick
turnaround, and limited QA/QC). A minimum number of
QC checks are required to assess accuracy and precision.
Remedy screening does not require a significant amount of
replication in the test samples and the analytical tests
performed. The need for accuracy checks such as matrix
spikes and blanks is also limited.
3.2.3 Remedy-Selection Testing
For remedy selection, DQOs are primarily quantitative in
nature. For example, a performance goal for remedy-
selection testing involving solvent extraction and chemical
dehalogenation may be to reduce polychlorinaicd biphe-
nyls (PCBs) to less than 30 ppm in soils (the target cleanup
goal specified for the site). The data required to meet this
quantitative goal are derived from detailed waste character-
ization and performance testing. These data will be used to
select one of the technologies in the ROD.
Because data used in support of remedy selection must
have a high level of confidence, QA Categories III or II
are recommended for remedy-selection testing. These
categories are designed to support the evaluation and
selection of technologies. The PARCC parameters are
therefore narrowly defined and test data arc well docu-
mented. The selection of Category III (less stringent) or
Category II (more stringent) for ircatability testing de-
pends on the intended use of the data and on time and cost
constraints.
Narrow confidence limits are typically required at this tier.
Quality control checks for accuracy and precision will be
more thorough than for remedy screening. A significant
amount of test sample and analytical sample replication
will be required to determine accuracy and precision pa-
rameters. The representativeness of the data must be care-
fully documented, and a sufficient amount of the data
generated should be judged valid. Standard sampling and
analysis techniques should be used whenever possible to
assure data comparability. The testing apparatus should be
designed to generate enough treated material to support this
QA program.
The need for detailed analyses and high-quality data at the
remedy-selection tier will result in significantly higher ana-
lytical costs and longer turnaround times compared with
those for remedy screening. These factors must be consid-
ered when establishing DQOs for remedy-selection
ireatability studies.
3.2.4 RD/RA Testing
The principal objective of RD/RA testing is to obtain quan-
titative performance, design, and cost data for use in the
implementation of the selected remedial technology. Data
quality objectives for RD/RA trcatabilily studies arc there-
fore primarily quantitative.
The need for design, cost, and performance information
will dictate the frequency of sampling and testing, the
required confidence limits, and the level of QA/QC. The
uses for RD/RA trcatability study data differ from those for
remedy-selection data, but the required level of data quality
will be the same or less. Therefore, QA Categories III or II
are recommended for RD/RA testing.
In general, RD/RA testing will involve significant replica-
tion in test sampling (collocated samples) and laboratory
analyses (split samples). Typically, PARCC parameters
arc narrowly defined and test daui arc well documented.
Confidence limits will be similar to those for remedy-
selection testing.
3.3 Identifying Sources for Treatability
Studies
3.3.7 General
Once the decision to conduct a trcatabilily study has been
made and the scope of the project has been defined, the
project manager must identify a qualified program contrac-
tor or technology vendor with the requisite technical capa-
bilities and experience to perform the work. Trcatabilily
studies can be performed in house or via several contract
mechanisms thai exist for the remedial and removal pro-
grams under CERCLA.
In-house Capabilities
In support of Supcrfund, EPA has created several programs
and documents to assist EPA site managers in the perfor-
mance of treaiability studies. These include the Supcrfund
Technical Assistance Response Team (START), the RREL
Remedy-Screening Treatability Study Laboratory, the En-
vironmental Response Team (ERT), and the Inventory of
Treatabilily Study Vendors.
Superfund Technical Assistance Response Team. Site-
specific, long-term assistance is available to project man-
agers through START. Sponsored by ORD-RREL. the
START program provides comprehensive engineering as-
sistance from early Rl/FS scoping through RA implemen-
tation at a limited number of sites. Sites arc chosen by the
26
-------
Regions for START support because of ihcir complex con-
taminants and matrices.
Treatability support services available to project managers
through START include:
• Identification of potentially applicable technology op-
tions
• Determination of need for trcatability studies
• Performance of remedy-screening trcatabiliiy studies
• Review of trcatability study Project Plans
• Oversight of PRP-conducied ireatability studies
• Review of PRP dclivcrublcs and final reports
Treatability support through the START program can be
obtained by contacting the RREL Technical Support Branch
in Cincinnati, Ohio.
RREL Remedy-Screening Trcatabiliiy Study Laboratory.
The RREL has developed a series of remedy-screening
ueatability tests. These protocols arc designed to provide
the Regions with inexpensive, preliminary assessments of
the potential feasibility of a given technology for remediating
contaminated soil. In-house testing can be performed for:
• Soil vapor extraction
• Solvent extraction
• Soil washing
• Soil flushing
• Biological degradation
• Chemical dehalogcnaiion
• Solidification/stabilization
• Thermal desorption
• Incineration technologies
Regions can have these tests performed by contacting the
RREL Technical Support Branch in Cincinnati, Ohio (sec
Appendix A).
Environmental Response Team. Serving as the EPA's in-
house consultants on Supcrfund issues and oil spills, the
Environmental Response Team provides technical sup-
port to OSCs and RPMs for both emergency removal and
long-term remedial actions. With support from the Re-
sponse Engineering and Analytical Contractor, the ERT's
Alternative Technology Section can design and perform
remedy-screening and remedy-selection treatability stud-
ies for a wide range of technologies. The Section can
provide testing oversight and evaluate and interpret
trcaiability lest results. Regions can request ircatabiliiy
study support by contacting the ERT in Edison, New
Jersey (see Appendix A).
Inventory of Treatabiliry Study Vendors. The ORD has
compiled a list of vendors and contractors who have ex-
pressed an interest in performing trcatabiliiy studies. This
document, entitled Inventory of Treatability Study Ven-
dors. Volumes I and II (EPA 199()a), was compiled from
information received from contractor/vendor responses to a
published request. It lists commercial firms thai offer
trcaiability study services and describes their capabilities.
(This information has not been verified by EPA.) The
inventory is sorted by treatment technology, contaminant
group, and company name. It can be searched electroni-
cally by contacting the EPA Alternative Treatment Tech-
nology Information Center (ATTIC) (sec Appendix A).
Figure 4, an example page from the document, shows the
types of information the inventory contains.
Contractor.1; or Vendors
Three available methods for obtaining trcauibiliiy study
services from contractors arc discussed here.
ARCS, ERCS, and TAT Contracts. Alternative Remedial
Contracts Strategy (ARCS) contracts arc used to obtain the
program management and technical services needed to sup-
port remedial response activities at CERCLA sites. To
retain a ircatabiliiy study vendor through this contract
mechanism, the EPA project manager (in conjunction with
the EPA contract officer) must issue to the prime contrac-
tor a Work Assignment outlining the required tasks. The
prime contractor may clcci to perform this work or to
assign ii to one of iis subcontractors. Emergency Response
Cleanup Services (ERCS) and Technical Assistance Team
(TAT) contracts provide similar support services al
CERCLA removal sites. Both ERCS and TAT contractors
can be directed to perform trcauibility studies.
Technical Assistance and Support Contracts. When a spe-
cific waste at a particular site requires the specialized ser-
vices of a contractor that can treat that waste (e.g., a mixed
radioactive/hazardous waste) and such services arc not avail-
able from firms accessible through existing contracts, the
EPA project manager may need to investigate which firms
27
-------
TICATMUITT ITUOt VENDORS iT COMPANY NAME
O COMPANY:
Address:
City:
Contact:
Treatment Technology: ACTIVATED CARBON
Other Treatment Capability: 5 TECHNOLOGIES
CURRENT AVAILABLE FACILITY: LABORATORY
Permitting Status: EPA ID AS SMIL KNERATOR
Mobile Facility? YES
Bench Scale? YES
Unit Capacity: INFORMATION NOT PROVIDED
Price Information: INFORMATION NOT PROVIDED
Media Treated: 1. AQUEOUS MEDIA
3.
5.
Contaminant 1. HALOCENATEO NONVOLATIIES
Croups 3. NONNALOCfNATED NONVOt.ATII.ES
Treated: S. NONVOLATILE METALS
7. ORGANIC CTAN1DES
9. VOLATILE METALS
11.
Other Contaminant Croups That Can Be Treated:
Experience at Superfuid Sites?
OSUPERFUND SITE * 1: A 1 F MATERIAL RECLAIMING
Site Location: GREENVILLE
Start Date: 00/64
Unit Utilized for/at Site: INFORMATION NOT PROVIDED
Price Information: INFORMATION NOT PROVIDED
Media Treated 1. AQUEOUS MEDIA
3.
5.
Contaminant 1. VOLATILE METALS
Croups 3.
Treated: 5.
7.
9.
11.
Other Contaminant Croups Treated:
RJPERFUND SITE « 2: AMERICAN CREOSOTE
location: JACKSON
Start Date: 00/86
Unit Utilized for/at Site: INFORMATION NOT PROVIDED
Price Information: INFORMATION NOT PROVIDED
Hedia Treated: 1. AQUEOUS MEDIA
3.
5.
Contaminant 1. NONVOLATILE METALS
Croups 3. CREOSOTE
O Treated: 5.
7.
9.
11.
Other Contaminant Croupe:
Company Type: SMALL BUS
State: Zip:
Phone:
Studiet/Month: INP
Fined Facility? YES
Pilot Scale? NO
Location: ATLANTA, CA
2. ORGANIC LIQUID
4.
Other:
2. HALOCENATED VOLAT1LES
4. NONNALOCENATEO VOLATILES
6. ORGANIC CORROSIVES
6. PCS*
10.
12.
NOT SPECIFIED
YES
EPA Region: 5 ID f: 17
State: IL
End Date: INP
2.
4.
Other:
2.
4.
6.
8.
10.
12.
EPA Region: S ID •: 72
State: in
End Date: INP
2.
4.
Other:
2. PCBs
4.
6.
8.
10.
12.
OTNEI ORGAN ICS
Figure 4. Information contained in the ORD Inventory of Treatability Study Vendors.
28
-------
with this specialized capability are accessible through other
contracting mechanisms. Access to technical assistance
and support contracts may be available through the RREL,
the U.S. Bureau of Mines, or the U.S. Army Corps of
Engineers.
Request for Proposal. In the absence of an existing con-
tracting mechanism for accessing the required treatability
study services for a specific waste at a particular site, a new
contracting mechanism can be established. This will gen-
erally be the prime mechanism by which PRPs obtain
treatability study services. Obtaining the services of a
specific firm through a new contracting mechanism usually
involves three steps: 1) a request for proposal (RFP), 2) a
bid review and evaluation, and 3) a contract award. (Note:
This can be a time-consuming process.)
An RFP is an invitation to firms to submit proposals to
conduct specific services, li usually contains the following
key sections:
• The type of contract to be awarded (e.g., fixed-price or
cost plus fixed fee)
• Period of performance
• Level of effort
• Type of personnel (levels and skills)
• Project background
• Scope of work
• Technical evaluation criteria
• Instructions for bidders (e.g., due date, format, as-
sumptions for cost proposals, page limit, and number
of copies)
Appropriate firms listed in ORD's Inventory ofTreatabiliry
Study Vendors should be notified of the RFP in accordance
with the Federal Acquisition Regulations. Proposals sub-
mitted by a fixed due date in response to an RFP go to
several reviewers to determine the abilities of the prospec-
tive firms to conduct the required services. The technical
proposals should be evaluated (scored) with a standard
rating system that is based on the technical evaluation
criteria presented in the RFP. Contract award should be
based on a firm's ability to meet the technical requirements
of the testing involved, its qualifications and experience in
conducting similar studies, the availability and adequacy of
its personnel and equipment resources, and (other things
being equal) a comparison of cost estimates.
3.3.2 Remedy Screening
Remedy screening involves relatively simple tests that re-
quire no special equipment. These studies can often be
performed generically (as discussed in Subsection 2.5.4)
by the RREL; by the ARCS, ERCS, or TAT contractor; or
by the State or PRP prime support services contractor.
3.3.3 Remedy-Selection Testing
Remedy-selection testing of proven or demonstrated tech-
nologies can sometimes be performed by the ARCS, ERCS,
or TAT contractor. Tests involving innovative technolo-
gies, however, may require special vendor-specific capa-
bilities that are only accessible through technical assistance
and support contracts or an RFP.
3.3.4 RD/RA Testing
Post-ROD testing entails more complex tests involving the
use of specialized equipment. Because such capabilities
may not be available through any existing contracting
mechanism within the Agency, it may be necessary to issue
an RFP to obtain RD/RA ircauibility study services. The
RFP will generally be issued by the designer.
3.4 Issuing the Work Assignment
The Work Assignment is a contractual document thai out-
lines the scope of work to be provided by the contractor. It
presents the rationale for conducting the study, identifies
the waste stream and tcchnology(ics) to be tested, and
specifies the tier(s) of testing required. Table 6 presents the
suggested organization of the trcauibility study Work As-
signment.
3.4.7 Background
The background section of the Work Assignment describes
the site, the waste stream, and the treatment technology
under investigation. Site-specific concerns that may affect
waste handling, the experimental design, or data interpreta-
tion, as well as specific process options of interest, should
be duly noted. The results of any previous trcatability
studies conducted at the site also should be included.
3.4.2 Test Objectives
This section defines the objectives of the treatability study
and the intended use of the data (i.e., to determine potential
feasibility; to develop performance or cost data for remedy
selection; or to provide detailed design, cost, and perfor-
mance data for remedy implementation). The test objcc-
29
-------
Table 6. Suggested Organization of Treatabiiity
Study Work Assignment
1. Background
1.1 Site description
1.2 Waste stream desjription
1.3 Treatment technology description
1.4 Previous treatability studies at the site
2 Test Objectives
3. Approach
3.1 Task 1 - Work Plan preparation
3.2 Task 2 - SAP, HSP, and CRP
preparation
3.3 Task 3 - Treatability study execution
3.4 Task 4 - Data analysis and
interpretation
3.5 Task 5 - Report preparation
3.6 Task 6 - Residuals management
4. Reporting Requirements
4.1 Deliverables
4.2 Monthly reports
5. Schedule
6. Level of Effort
lives will include performance goals that are based on
established cleanup criteria for the site or, when such crite-
ria do not exist, on contaminant levels that are protective of
human health and the environment. If the treatability study
Work Assignment is issued before site cleanup goals have
been established, the test objectives should be written with
enough latitude to accommodate changes as the trcatabiliiy
testing proceeds without modifying the Work Assignment.
3.4.3 Approach
The approach describes the manner in which the treatability
study is to be conducted. It should address the following
six tasks: 1) Work Plan preparation; 2) Sampling and
Analysis Plan (SAP), Health and Safely Plan (HSP). and
Community Relations Plan (CRP) preparation; 3) ircauibiliiy
study execution; 4) data analysis and interpretation; 5)
report preparation; and 6) residuals management.
Task 1 - Work Plan Preparation
This task oullincs the elements to be included in the Work
Plan. If a project kickoff meeting is needed to define ihc
objectives of ihc ircatability study or 10 review ihc experi-
mental design, it should be specified here. The contractor
should not begin work on subsequent tasks until receipt of
ihc project manager's approval of the Work Plan.
Task 2 - SAP. HSP, and CRP Preparation
This task describes activities specifically related to the
treatability study that should be incorporated into the exist-
ing site SAP, HSP, and CRP. Examples of such acuviiics
include field sampling and waste stream characterization,
operation of pilot-plant equipment, and public meetings to
discuss treatabilily study findings.
Task 3 - Trealability Study Execution
Requirements for executing the treatability study are out-
lined in this task. It should include requirements uV; the
contractor review the literature and site-specific informa-
lion, identify key parameters for investigation, and specify
conditions of the test This task also should identify guid-
ance documents (such as this guide or other technology-
specific protocols) to be consulted during the planning and
execution of the study.
Task 4 • Data Analysis and Interpretation
This lask describes how dala from the trcatability study will
be used in the evaluation of the remedy. If statistical
analysis of the data will be necessary, the requirements
should be stipulated here.
Task 5 - Report Preparation
This lask describe? the contents and organization of the
final project report. If multiple tiers of testing are expected,
an interim report may be requested upon completion of
each tier. The contractor should be required to follow ihc
reporting format outlined in Subsection 3.12.
Task 6 - Residuals Management
Residuals generated by trcatability testing must be man-
aged in an environmentally sound manner. This uisk should
specify whether project residuals arc to be rciurncd to the
site or shipped 10 an acceptable offsitc facility. In the latter
case, the responsible waste generators (lead agency, PRP,
or contractor) should be clearly identified.
3.4.4 Reporting Requirements
This section identifies the project dclivcrablcs and monthly
reporting requirement. Project dclivcrablcs include the
Work Plan; ihc SAP, HSP, and CRP (as appropriaic); and
interim and final reports. It should indicate the formal
specifications (as outlined in this guidance) and ihc number
of copies 10 be delivered. All remedial and removal Work
Assignments must include a requirement for one camera-
ready master copy of ihc trcauibiliiy study report to be
30
-------
provided to the Office of Research and Development (EPA
1989e) for use in updating the RREL Trcatability Data
Base. (The report should be sent to the address listed in
Subsection 3.12.)
Monthly reports should summarize the progress made in
the current month, projected piogress for the coming month,
any problems encountered, and expected versus actual costs
incurred.
3.4.5 Schedule
The schedule establishes the timcframe for conducting the
treatability study and includes due dates for submission of
the major project dclivcrablcs. Sufficient time should be
allowed for approval of the Work Plan, subcontractors, and
other required administrative approvals; site access and
sampling; analytical turnaround; equipment setup and shake-
down; data analysis and interpretation; and review and
comment on reports.
3.4.6 Level of Effort
The level of effort estimates the number of technical hours
required to complete the project. Special skills or expertise
are required for most trcaiability studies, and these require-
ments should be so noted.
3.5 Preparing the Work Plan
Treatability studies must be carefully planned to ensure
that the data generated are useful for evaluating the feasi-
bility or performance of a technology. The Work Plan,
which is prepared by the contractor when the Work Assign-
ment is in place, sets forth the contractor's proposed techni-
cal approach for completing the tasks outlined in the Work
Assignment. It also assigns responsibilities and establishes
the project schedule and costs. Table 7 presents the sug-
gested organization of a ireatabilily study Work Plan. The
Work Plan must be approved by the project manager before
subsequent tasks are initiated. Each of the principal Work
Plan elements is described in the following subsections.
3.5.1 Project Description
The project description section of the Work Plan provides
background information on the site and summarizes exist-
ing waste characterization data (matrix type and character-
istics and the conceniraiions and distribution of the con-
taminants of concern). This information can be obtained
from the Work Assignment or other background docu-
ments such as the Rl. The project description also specifics
the type of study to be conducted, i.e., remedy screening.
Table 7. Suggested Organization of Treatability
Study Work Plan
1. Project Description
2. Treatment Technology Description
3. Test Objectives
4. Experimental Design and Procedures
5. Equipment and Materials
6. Sampling and Analysis
7. Data Management
8. Data Analysis and Interpretation
9. Health and Satety
10. Residuals Management
11. Community Relations
12. Reports
13. Schedule
14. Management and Staffing
15. Budget
remedy-selection testing, or RD/RA testing. For ircatabilily
studies involving multiple tiers of testing, this section states
how the need for subsequent testing will be determined
from the results of the previous tier.
3.5.2 Treatment Technology
Description
This section of the Work Plan briefly describes the treat-
ment technology to be tested. It may include a flow dia-
gram showing the input stream, the output stream, and any
side streams generated as a result of the treatment process.
For ireatability studies involving treatment trains, the tech-
nology description addresses.all the unii operations the
system comprises. A description of the prc- and posurcai-
mcnt requirements also may be included.
3.5.3 Test Objectives
This section of the Work Plan defines the objectives of the
trcaiability study and the intended use of the data (i.e., to
determine potential feasibility; to develop performance or
cost data for remedy selection; or to provide detailed de-
sign, cost, and performance data for remedy implementa-
tion). The lest objectives will include performance goals
that arc based on established cleanup criteria for the site or,
when such criteria do not exist, on contaminant levels that
arc protective of human health and the environment.
3.5.4 Experimental Design and
Procedures
The experimental design identifies the tier and scale of
31
-------
testing, the volume of waste material lo be tested, the
critical parameters, and the type and amount of replication.
Examples of critical parameters include pH, reagent dos-
age, temperature, and reaction (or residence) time. Some
form of replication is usually incorporated into a ireatability
study to provide a greater level of confidence in the data.
Two methods are used to collect different types of test
sample replicates:
1) Dividing a sample in half or thirds at theend of the
experiment and analyzing each fraction. This
method provides information on laboratory error.
2) Analyzing two or three samples prepared inde-
pendently of each other under the same test con-
ditions. This method provides information on
total error.
The data quality objectives and the costs associated with
replication must be considered in the design of the experi-
ment. A matrix outlining the test conditions and the num-
ber of replicates, such as the example in Figure 5, should be
included in the Work Plan.
The specific steps to be followed in the performance of the
ireatability study are described in uv standard operating
procedures (SOP). The SOP should be sufficiently detailed
to permit the laboratory or field technician to conduct the
lest, to operate the equipment, and to collect the samples
with minimal supervision, as shown in Example 4. The
SOP can be appended to the Work Plan.
3.5.5 Equipment and Materials
This section lists the equipment, materials, and reagents
that will be used in the performance of the ireatability
study. The following specifications should be provided for
each item listed:
• Quantity
• Volume/capacity
• Calibration or scale
• Equipmenl manufacturer and model number
• Reagent grade and concentration
A diagram of the tesi apparatus also should be included in
the Work Plan.
3.5.6 Sampling and Analysis
A Sampling and Analysis Plan is required for all field
activities conducied during ihe Rl/FS. This section de-
scribes how the existing SAP will be modified to address
field sampling, waste characterization, and sampling and
analysis activities in support of the treaiability siudy. It
describes the kinds of samples thai will be collected and
specifies the level of QA/QC required. (Preparation of the
ireatability study SAP is discussed in Subsection 3.6.)
Appendix C contains waste feed characterization param-
eters specific lo biological, physical/chemical, immo-
bilization, thermal, and in situ treatment technologies. Gen-
erally, these are ihe characterization parameters that must
be established before a trcaiabiliiy test is conducted on the
corresponding technology. Site-specific conditions may
necessitate the use of additional parameters.
3.5.7 Data Management
This section of the Work Plan describes the procedures for
recording observations and raw data in the field or labora-
tory, including the use of bound notebooks, data collection
sheets, and photographs. If proprietary processes are in-
volved, this section also describes how confidential informa-
lion will be handled.
3.5.8 Data Analysis and Interpretation
This section of ihe Work Plan describes ihe procedures that
will be used lo analyze and interpret data from ihe treatabiliiy
Soil
X
Y
1
A%
3
3
- Zeolite 1
B%
3
3
C%
3
3
A%
3
3
- Zeolite
B%
3
3
C%
3
3
III • limestone
3
3
IV • control
3
3
Figure 5. Example test matrix for zeolite amendment remedy-selection treatability study.
32
-------
EXAMPLE 4. TREATABILITY STUDY STANDARD OPERATING PROCEDURE
Standard Operating Procedure for Thermal Desorption Remedy-Screening Treatability Study
1. Define and record planned experiment in the data book (i.e., time, temperature, soil, etc.).
2. Weigh the empty clean tray.
3. Transfer a representative aliquot of prepared soil from the jar to the tray with a stainless steel
spatula.
4. Weigh the soil and tray and adjust the soil quantity to achieve a uniform layer approximately 2.5
to 3 mm deep in the bottom of the tray.
5. Distribute and level the soil within the tray.
6. Turn on the purge-gas flow to the proper setting on the rotameter.
7. Place the tray with soil in the oven at ambient temperature and close the oven door.
8. Set the oven temperature controller set-point to the target test temperature and start the timer.
9. Monitor and record the temperatures and time periodically throughout the test period.
10. When the prescribed residence time at the target temperature is reached, shut off the oven
heater and purge-gas flow and open the oven door.
11. Cautiously withdraw the hot tray and soil with special tongs, place a cover on the tray, and
place the covered tray in a separate hood to cool tor approximately 1 hour.
12. Weigh the tray (without cover) plus treated soil.
13. Transfer an aliquot (typically about 20 g) of treated soil from the tray to a tared, 60-cm3, wide-
mouth, amber bottle with Teflon-lined cap. Code, label, and submit this aliquot for analysis.
Transfer the remainder of the treated soil to an identical type bottle, label, and store as a
retainer.
14. Clean the tray, cover, and nondisposable implements by the following procedure:
• Rinse with acetone and wipe clean.
• Scrub with detergent solution and rinse with hot tap water followed by distilled water.
• Rinse with acetone and allow to dry.
• Rinse three times with methylene chloride (i.e., approximately 15 to 25 ml each rinse for
the tray).
• Air dry and store.
study, including methods of data presentation (tabular and
graphical) and statistical evaluation. (Dam analysis and
interpretation are discussed in Subsection 3.11.)
5.5.9 Health and Safety
A Health and Safety Plan is required for all cleanup opera-
tions involving hazardous substances under CERCLA and
for all operations involving ha/ardous wastes that arc con-
ducted at RCRA-rcgulatcd facilities. This section of the
Work Plan describes how ihe existing site or facility HSP
will be modified to address the hazards associated with
ireatability testing. Hazards may include, but arc not lim-
ited to, chemical exposure; fires, explosions, or spills;
generation of toxic or asphyxiating gases; physical haz-
ards; electrical ha/ards; and heat stress or frostbite. (Prepa-
ration of the trcatability study HSP is discussed in Subsec-
tion 3.7.)
3.5.10 Residuals Management
This section of the Work Plan describes the management of
treatability study residuals. Residuals generated by
ircaiability testing must be managed in an environmentally
sound manner. Early recognition of the types and quanti-
ties of residuals that will be generated, the impacts lhat
managing these residuals will have on the project schedule
and costs, and the roles and responsibilities of the various
33
-------
panics involved in ih> generation 01 residuals is irvporiant
for their proper disposal.
The Work Plan should include estimates of both the types
and quantities of residuals expected to be generated during
treaiability testing. These estimates should be based on
knowledge of the treatment technology and the experimen-
tal design. Project residuals may include the following:
• Unused waste not subjected to testing
• Treated waste
• Treatment residuals (e.g., ash, scrubber water, and
combustion gases)
• Laboratory samples and sample extracts
• Used containers or other expendables
• Contaminated protective clothing and debris
This section outlines how trcatability study residuals will
be analyzed to determine if they arc hazardous wastes and
specifies whether such wastes will be returned to the site or
shipped to a permitted treatment, storage, or disposal facil-
ity (TSDF) (see Subsection 3.9). In the latter case, this
section also identifies the waste generator (lead agency,
responsible party, or contractor) and delineates the param-
eters that will be analyzed for properly manifesting the
waste and for obtaining disposal approval from the TSDF
(see Table 8).
3.5.7 7 Community Relations
A Community Relations Plan is required for all removal
and remedial response actions under CERCLA. This sec-
tion describes the community relations activities that will
be performed in conjunction with the treaiability study.
These activities include, but arc not limited to, preparing
fact sheets and news releases, conducting workshops or
community meetings, and maintaining an up-to-date infor-
mation repository. (Conducting community relations activi-
ties for trcatability studies is discussed in detail in Subsec-
tion 3.8.)
3.5.72 Reports
This section of the Work Plan describes the preparation of
interim and final reports documenting the results of the
ircaiabilily study. For trcaiabiliiy studies involving more
than one tier of testing, interim reports (or project brief-
ings) provide a means of determining whether to proceed to
the next tier. This section also describes the preparation of
Table 8. Typical Waste Parameters Needed to Obtain Disposal Approval at an Offsite Facility8
Incineration parameters
Total solids
% Water
% Ash
PH
Specific gravity
Flash point
Btu/pound
Total sulfide
Total sulfur
Total organic nitrogen
Total cyanide
Total phenolics
Total organic halogen (TOX)
Polychlorinated biphenyls (PCBs)
Total RCRA metals (eight)
TCLP metals
TCLP organics (D-list)
Priority pollutant organics
Volatile
Semivoiatile (BN/A-extractabie)
Remaining F-listed solvents
Treatment parameters
pH
Specific gravity
Oil and grease
Total organic carbon (TOC)
Total sulfide
Total cyanide
Total phenolics
Total metals (RCRA plus Cu, Ni, Zn)
TCLP metals
TCLP organics (D-list)
Landfill parameters (solids only)
% Water
% Ash
pH
Specific gravity
Total sulfide
Total cyanide
Total phenolics
PCBs
TCLP metals (extraction and RCRA)
TCLP organics (D-list)
TCLP solvents (F-list)
aAnalysis of these parameters may be required unless they can be ruled out based on knowledge of
the waste.
34
-------
monthly reports detailing the current and projected progress
on the project. (Trcatability study reporting is discussed in
detail in Subsection 3.12.)
3.5.75 Schedule
The Work Plan should contain a schedule indicating the
planned starting and ending dates for the tasks outlined in
the Work Assignment. The length of a trcaiability study
will vary with the technology being investigated and the
level of testing being conducted. Entire remedy-screen ing
studies can usually be performed within a few weeks.
Remedy-selection studies, however, may require several
months. In addition to the time required for actual testing, the
schedule must allow time for obtaining approval of the vari-
ous plans; securing any necessary environmental, testing, or
trdnsporuu'on permits; shipping analytical samples and re-
ceiving results; seeking review and comment on the project's
delivcrables; and disposing of the project's residuals.
The schedule may be displayed as a bar chart, such as that
shown in Figure 6. In this example, both remedy-screening
and remedy-selection trcatability studies arc planned. Per-
formance of the selection studies is contingent upon the
results of the screening studies, which arc presented in the
Interim Report. In this particular schedule, the actual
treatability tests (Subtasks 3b and 7a) will require only 1 to
2 weeks to perform. The entire two-tiered study, however,
spans a period of 8 months.
3.5.74 Management and Staffing
This section of the Work Plan identifies key management
and technical personnel and defines specific project roles
and responsibilities. The line of authority is usually pre-
sented in an organization chart such as that shown in Figure
7. The EPA Project Manager is responsible for project
planning and oversight. At Federal- and State-lead sites,
the remedial contractor directs the trcatability study and is
responsible for the execution of the project tasks. At
private-lead sites, the PRP performs this function. The
trcatabiliiy study may be subcontracted wholly or in part to
a vendor or testing facility with expertise in the technology
being evaluated.
3.5.75 Budget
The treatability study budget presents the projected costs
for completing the ircatability study as described in the
Work Plan. Elements of a budget include labor, adminis-
trative costs, and fees: equipment and reagents; site prepa-
ration (e.g., building a concrete pad) and utilities; permit-
ting and regulatory fees; unit mobilization; on-sccnc health
and safety requirements; sample transportation and analy-
sis; emissions and effluent monitoring and treatment: um;
decontamination and demobilization; and residuals trans-
portation and disposal. Appendix B discusses these vari-
ous cost elements.
The size of the budget will generally reflect the complexity
of the treatability study. Consequently, the number of
operating parameters chosen for investigation at the rem-
edy-selection tier and the approach used to obtain these
measurements will often depend on the available funding.
For example, for some treatment processes it may be less
costly lo obtain data on contaminant reduction versus reac-
tion time at the completion of a test run rather than periodi-
cally throughout the test. This kind of information can be
obtained from the technology vendor during the planning
of the ircatability study.
Analytical costs can have a significant impact on the
project's overall budget. Sufficient funding must be allot-
ted for the amount of analytical work projected, the chemi-
cal and physical parameters to be analy/.cd, and the re-
quired turnaround lime. Specially analyses (e.g., for diox-
ins and furans) can quickly increase the analytical costs.
A 34-week rcmcdy-scrccning/rcmcdy-sclcction ircatability
study such as the one presented in Figure 6 can be per-
formed at a cost of between 550,000 and 5100,000.
3.6 Preparing the Sampling and
Analysis Plan
3.6.7 General
A Sampling and Analysis Plan is required for all field and
lest activities conducted to support a ircatabiliiy study. The
purpose of the SAP is to ensure that samples obtained for
characterization and testing arc representative and that the
quality of the analytical data generated is known. The SAP
addresses field sampling, waste characicri/ation, and sam-
pling and analysis of the treated wastes and residuals from
ihc icsiing apparatus or ircaimcm unit.
Table 9 presents the suggested organi/Jtion of the trcatabiliiy
study SAP. The SAP consists of two parts-thc Field Sam-
pling Plan (FSP) and the Quality Assurance Project Plan
(QAPP).
Field Sampling Plan
The FSP component of the SAP describes ihc sampling
objectives; the type, location, and number of samples to be
collected: the sample numbering system; the necessary
equipment and procedures for collecting the samples; the
35
-------
TASK
Taskl
Work Plan Preparation
Task 2
SAP & HSP Preparation
Task 3
Remedy Screening
Treatabiliiy Study Execution
3a - Field Sampling/Waste Characterization
3b - Equipment Setup/Testing/Sampling
3c - Sample Analysis
Task 4
Data Analysis and Interpretation
Tasks
Interim Report Preparation * Review
Task 6
Test Plan Revision (if necessary)
Task 7
Remedy Selection
Treatabiliiy Study Execution
7a - Equipment Setup/Testing/Sampling
7b - Sample Analysis
Tasks
Data Analysis and Interpretation
Task 9
Final Report Preparation and Review
Task 10
Residuals Management
Span,
Weeks
3
5
4
1
3
1
4
1
2
3
2
Weeks from Project Start
i
•
2
M
•^
•
3
1M
r ^
•
4
2
r
S
6
7
M3
•w
8
M
•^
9
•4
r
10
M-3
^^-
11
•
12
13
M-D
•Tl
•
14
-7
r
•
15
•
16
17
M-e
•w
m
•
•
18
•
19
20
21
M 9 M'-10
^ -^
•I
•I
M
•^i
22
11
r
•
23
-
^
•
24
12
r
•
25
•
26
M
^
•
27
13
w
m
28
•
M
29
17
*r
30
31
M-14
•^
r
32
M
33
15
^
I
M 18
•w
34
M
16
^•
1
M 19
V
I
Ml Submit Work Plan Wk 2
M2 Receive Work Plan Approval Wk 3
M3 Submit SAP and HSP Wk 6
M4 Receive SAP and HSP Approvals Wk 8
M-5 Collect and Submit Field Samples Wk 9
M6 Receive Waste Characterization Results Wk 12
M7 Submit Treatabiliiy Samples Wk 13
M8 Receive Treatability Results Wk 16
M9 Submit Interim Report Wk 19
M-10 Project Briefing Wk 20
Mil Submit Revised Work Plan Wk 21
M 12 Submit Treatabiliiy Samples Wk 23
M-13 Receive Treatability Results Wk 26
M-14 Submit Draft Report Wk 30
M-15 Receive Review Comments Wk 32
M 16 Submit Final Report Wk 34
M-17 Submit Disposal Application Wk 28
M 18 Receive Disposal Approval Wk 32
M 19 Ship Residuals lot Disposal Wk 34
Figure 6. Example project schedule for a two-tiered chemical dehalogenation treatabiiity study.
-------
sample chain-of-custody procedures; and the required pack-
aging, labeling, and shipping procedures.
The sampling objectives must support the test objectives of
the treaiability study. For example, if an objective of RD/
RA testing is to investigate process upsets and recovery,
the objective of field sampling should be to collect samples
representing the "worst case." If soils will be blended in
the full-scale process, however, the field sampling objec-
tives should be to collect samples representing "average"
conditions at the site.
Whatever the sampling objectives, the samples collected
must be representative of the conditions being evaluated.
Guidance on representative samples and statistical sam-
pling is contained in Test Methods for Evaluating Solid
Waste (EPA 1986).
Additional guidance for the selection of field methods,
sampling procedures, and chain-of-custody requirements
can be obtained from A Compendium of Supcrfund Field
Operations Methods (EPA 1987b).
Quality Assurance Project Plan
The second component of the SAP, the QAPP, details the
quality assurance objectives (precision, accuracy, repre-
sentativeness, completeness, and comparability) for criti-
cal measurements and the quality control procedures es-
tablished 10 achieve the desired QA objectives for a spe-
cific trcatability study. Guidance for preparing the QAPP
can be obtained from Quality Assurance Procedures for
RREL (EPA 1989d) and Interim Guidelines and Specifi-
cations for Preparing Quality Assurance Project Plans
(EPA 1980). In general, QAPPs arc based on the lypc of
project being conducted and on the intended use of the
data generated by the project. The QAPP recommended
in Table 9 corresponds to the QA Category II plan pre-
sented in Quality Assurance Procedure for RREL. This
plan should be implemented only for remedy-selection
treaiability studies requiring exceptionally high levels of
QA (i.e., where ucatability data will play an important
role in the ROD). As discussed in the following subsec-
tions, less stringent QAPPs will be adequate for all other
ircatability studies.
3.6.2 Remedy Screening
Remedy screening requires a less stringent level of QA/
QC. Technologies determined to be potentially feasible
through remedy screening arc evaluated further at the
remedy-selection tier; therefore, thcQA/QC requirements
associated with this screening arc less rigorous. Never-
theless, the test data should be well documented. The
Quality Assurance Officer
hi
Health & Safety Officer
Work Plan
Preparation
Task Leader
EPA
Remedial Project
Manager
EPA
Technical Experts
Contractor
Work Assignment
Manager
SAP & HSP
Preparation
Task Leader
Subcontractor
Manager
Treatability Study
Execution
Task Leader
Data Analysis &
Interpretation
Task Leader
Final Report
Preparation
Task Leader
Figure 7. Example project organization chart.
37
-------
Table 9. Suggested Organization of a
Treatability Study Sampling and Analysis Plan
Field Sampling Plan
1. Site Background
2. Sampling Objectives
3. Sampling Location and Frequency
4. Sample Designation
5. Sampling Equipment and Procedures
6. Sample Handling and Analysis
Quality Assurance Project Plan
1. Project Description
2. Project Organization and Responsibilities
3. Quality Assurance Objectives
4. Site Selection and Sampling Procedures
5. Analytical Procedures and Calibration
6. Data Reduction, Validation, and Reporting
7. Internal Quality Control Checks
8. Performance and Systems Audits
9. Calculation of Data Quality Indicators
10. Corrective Action
11. Quality Control Reports to Management
12. References
Appendices
A. Data Quality Objectives
B. EPA Methods Used
C. SOP for EPA Methods Used
D. QA Project Plan Approval Form
Category IV QAPP is recommended for remedy-screening
ircatabilily studies.
3.6.3 Remedy-Selection Testing
Remedy-selection testing requires a moderately to highly
stringent level of QA/QC. The dan generated in remedy-
selection testing are generally used for evaluation and
selection of the remedy; therefore, the QA/QC associated
with this tier should be rigorous and the test data well
documented. The Category III QAPP will provide a suffi-
cient level of quality assurance for most remedy-selection
ircatabilily studies. In cases where remedy-selection
data will be highly scrutinized or have a significant im-
pact on decision making, the Category II QAPP may be
required.
3.6.4 RD/RA Testing
Trcatability testing to support remedial design/remedial
action requires a moderately to highly stringent level of
QA/QC. The data generated in RD/R A testing arc used in
support of remedy optimization and implementation; there-
fore, the QA/QC associated with this tier should be rigor-
ous and the test data well documented. In most cases, the
Category III QAPP will provide data of sufficient quality
forRD/RA trcatability studies.
3.7 Preparing the Health and Safety
Plan
3.7.7 General
A project-specific Health and Safety Plan is required for all
ircatabilily studies conducted on site or at an offsitc labora-
tory or testing facility permitted under RCRA, including
research, development, and demonstration facilities. The
vendor or testing facility should submit the HSP with the
ircatabilily study Work Plan. The HSP describes ihc work
lo be performed in the field and in the laboratory, identifies
ihc possible physical and chemical hazards associated wiih
each phase of field and laboratory operations, and pre-
scribes appropriate protective measures to minimize worker
exposure. Hazards that may be encountered during
trcatability studies include the following:
• Chemical exposure (inhalation, absorption, or ingcs-
lion of conuminaied soils, sludges, or liquids)
• Fires, explosions, or spills
• Toxic or asphyxiating gases generated during storage
or treatment
• Physical hazards such as sharp ohiccts or slippery
surfaces
• Electrical hazards such as high-voltage equipment
• Heat stress or frostbite
Table 10 presents the suggested organization of the
instability study HSP, which addresses the Occupaiional
Safety and Health Administration (OSHA) requirements in
29 CFR 1910.120(b)(4). Guidance lor preparing the HSP
is contained in two documents-/! Compendium of Super-
fund Field Operations Methods (EPA 1987b) and Occupa-
tional Safety and Health Guidance Manual for Hazardous
Waste Site Activities (N1OSH/OSH A/USCG/EPA 1985).
Supervisors, equipment operators, and field technicians
engaged in onsitc opcraiions must satisfy the iraining re-
quircmcms in 29 CFR 1910.120(c) and must participate in
a medical surveillance program, as described in 29 CFR
1910.120(0- Laboratory personnel must be iraincd with
38
-------
Table 10. Suggested Organization of a
Treatability Study Health and Safety Plan
1. Hazard Analysis
2. Employee Training
3. Personal Protective Equipment
4. Medical Surveillance
5. Personnel and Environmental Monitoring
6. Site Control Measures
7. Decontamination Procedures
8. Emergency Response Plan
9. Conlined-Space Entry Procedures
10. Spill Containment Program
regard to container labeling and Material Safety Data Sheets
(MSDS) in accordance with the OSHA Hazard Communi-
cation Standard in 29 CFR 1910.1200. Before any treat-
ability studies arc initiated, the Health and Safety Officer
should conduct a briefing to ensure that all personnel arc
apprised of the HSP. The Health and Safety Officer also
should conduct inspections during the course of the
treaiability study to determine compliance with and effec-
tiveness of the HSP.
3.7.2 Remedy Screening
The safciy and health ha/jrds associated with remedy
screening are relatively minor because of ihc small vol-
umes of wastes that arc handled and subjected to testing. In
general, the HSP should provide for skin and eye protection
during the handling of wastes. It need not require respira-
tory protection if the tests arc conducted in a fume hood.
3.7.3 Remedy-Selection Testing
The HSP for a remedy-selection trcatabilily study must
provide for skin and eye protection during the handling of
wastes. It also may require respiratory protection when
treatment processes tested at the bench scale involve mix-
ing or aeration (e.g., solidification/stabilization, aerobic
biological treatment) that could generate dust or volatilize
organic contaminants. Because pilot-scale testing involves
significanUy greater volumes of waste, the health and safety
risks will increase.
3.7.4 RD/RA Testing
Pilot- and field-scale RD/RA trcatability studies may pose
significant health and safety hazards to operators and onsitc
personnel. The HSP must outline skin, eye, and respiratory
protection (Level C or higher); decontamination proce-
dures; and emergency procedures ^such as equipment shut-
down and personnel evacuation).
3.8 Conducting Community Relations
Activities
3.8.1 General
Community relations activities provide interested persons
an opportunity to comment on and participate in decisions
concerning site actions, including the performance of
treatability studies. Public participation in the removal, Rl/
FS, and RD/RA processes ensures that ihc community is
provided with accurate and timely information about site
activities. From the beginning of the RI/FS, a description
of the ireatability study activities that will be performed
during the feasibility study should be included in the dis-
cussion on how the alternatives will be delineated for the
particular site. Presenting clear, concise explanations of
trcatability studies (accompanied by appropriate graphics)
before activities have been performed will create a more
open and positive Agency/public relationship.
The Agency designs and implements community relations
activities according 10 CERCLA and the National Oil and
Hazardous Substances Pollution Contingency Plan. The
NCP requires the lead Agency to prepare a Community
Relations Plan for all remedial response actions and for all
removal actions of more than 45 days' duration, regardless
of whether RI/FS activities .arc fund-financed or conducted
by PRPs (40 CFR 300.67). This plan outlines all commu-
nity relations activities that will be conducted during the
RI/FS and projects the future activities required during
completion of remedial design and implementation. These
future activities arc outlined more clearly in a revised plan
developed after the feasibility study and before the reme-
dial design phase.
Guidance for preparing a CRP and conducting community
relations activities can be acquired from Community Rela-
tions in Supcrfund: A Handbook (EPA I988b). Table 11
presents the CRP organization suggested in this handbook.
Community interviews should be conducted before the
CRP is prepared. These interviews arc informal discus-
sions held with Suite and local officials, community lead-
ers, media representatives, and interested citizens to assess
the public's concern and desire to be involved in site re-
sponse activities. Discussions with citizens regarding the
possible need for conducting onsilc trcauibilily studies will
allow the Agency to anticipate and respond better to com-
munity concerns as ihc trcauibility testing process proceeds
and will allow government officials and citi/cns to under-
39
-------
Table 11. Suggested Organization of
Community Relations Plan
1. Overview of Community Relations Plan
2. Capsule Site Description
3. Community Background
4. Highlights of the Community Relations
Program
5. Community Relations Activities and
Timing
Appendices
A. Contact List of Key Community Leaders
and Interested Parties
B. Suggested Locations of Meetings and
Information Repositories
suind that several technologies may be tested before the
preferred alicmaiive(s) are listed in the final FS report.
Conducting treatability studies on site is a potentially con-
troversial issue within a community and may demand con-
siderable effort on the part of the Agency. As the site
investigation progresses, community relations activities
should focus on providing information to the community
concerning the technology screening process and on ob-
taining feedback on community concerns associated with
potentially applicable treatment technologies. Activities
may include, but are not limited to, the following:
• Preparing fact sheets and news releases describing
treatment technologies identified during the develop-
ment and screening of alternatives.
• Discussing the possibility of treaiability studies being
conducted during the initial public meeting. Present-
ing professionally produced video tapes or slide shows
on treatabiliiy studies at the public meeting can demon-
strate that the Agency is attempting to educate the
public regarding the treatability study process.
• Conducting a workshop to present to concerned citizens,
local officials, and the media the Agency's rationale for
choosing the treatment technologies to be studied.
• Holding small group meetings with involved members
of the community at regular intervals throughout the
Rl/FS process to discuss trcatability study findings and
site decisions as they develop.
• Ensuring citizen access to treatabilily study information
by maintaining a complete and up-to-date information
repository.
• Presenting results of the treatabilily studies performed
and explaining how these results influenced the selec-
tion of the remedy at the final RI/FS public meeting.
Fact sheets on the planned ireatability studies should be
made available to the public and should include a discus-
sion of trcatabiiity-spccific issues such as the following:
• Uncertainties (risk) pertaining to innovative tech-
nologies
• The degree of development of potentially applicable
technologies identified for trcauibiliiy testing
• Onsitc treaiability testing and analysis
• Offsitc transportation of contaminated materials
• Materials handling
• Residuals management
• RI/FS schedule changes resulting from the unexpected
need for additional trcatability studies
• Potential disruptions to the community
3.8.2 Remedy Screening
Remedy-screening treatabilily studies arc relatively low-
profile and, if conducted offsite, will require relatively few
community relations activities. Distributing fact sheets and
placing the results from remedy screening in the informa-
tion repository will generally be sufficient.
3.8.3 Remedy-Selection Testing
Bench-scale remedy-selection testing may not be particu-
larly controversial if conducted offsite. Onsitc bench-scale
testing, however, may require more community relations
activities.
Onsitc, pilot-scale testing may attraci considerable com-
munity interest. In some cases (e.g., onsite thermal treat-
ment), the strength of public opinion concerning trcatability
testing may not have been indicated by the level of interest
demonstrated during the RI and previous treaiability stud-
ies. Because of ihe very real poicntial for conflici and
misunderstanding at the remedy-selection testing stage of
the FS, it is vital that a strong program of community
relations and public pariicipaiion be established well in
advance of any trcatability testing.
Community acceptance is one of the nine RI/FS evaluation
40
-------
criteria. Remedy-selection testing may provide daL ih.jt
can convince a community of a technology's ability to
remediate a site effectively. Early, open, and consistent
communication with the public and their full participation
in the decision-making process may help 10 prevent the
testing, development, and selection of a remedy that is
unacceptable to the community and results in delayed site
remediation and higher remediation costs.
3.8.4 RD/RA Testing
Post-ROD trcaiability testing may not be especially contro-
versial within a community because the remedy or rem-
edies being investigated have already been reviewed and
selected during the RI/FS. Fact sheets and news releases
covering RD/RA ircatabilily study progress may be appro-
priate.
3.9 Complying With Regulatory
Requirements
Trcatability studies involving Supcrfund wastes arc subject
to various requirements under CERCLA (as amended in
1986 by SARA] and RCRA [as amended in 1984 by the
Hazardous and Solid Waste Amendments (HSWA)]. The
applicability of these requirements depends on whether the
studies arc conducted on site (e.g., in a mobile trailer) or at
an offsitc laboratory or testing facility.
Figure 8 summarizes the facility requirements for treatability
testing. Figure 9 summarizes the shipping requirements for
offsitc trcaiabilily testing. These requirements arc de-
scribed in the succeeding subsections.
3.9.1 Onsite Treatability Studies
Onsitc trcatability studies under CERCLA may be con-
ducted without any Federal, State, or local permits |40 CFR
300.400(e)(l)]; however, such studies must comply with
ARARs under Federal and State environmental laws to the
extent practicable or justify a waiver under CERCLA Sec-
tion 121(d)(4). For example, ircatability studies involving
surface-water discharge must meet effluent limitations even
though a discharge permit is not required.
5.9.2 Offsite Treatability Studies
Section 121 (d)(3) of CERCLA and Revised Procedures for
Implementing Off-Site Response Actions (the "Revised Off-
Site Policy") (EPA 1987c) generally state that offsitc facili-
ties that receive CERCLA wastes must be 1) operating in
compliance with applicable Federal and State laws, and 2)
controlling any relevant releases of hazardous substances
to the environment. Currently, the Revised Off-Site Policy
docs not specifically exempt the transfer of CERCLA wastes
offsite for trcatability studies; therefore, off site laboratories
or testing facilities that receive CERCLA wastes must be in
compliance with the offsitc requirements.
Offsitc ircatability studies under CERCLA must be con-
ducted under appropriate Federal or Slate permits or autho-
rization and other legal requirements. Two alternatives to a
full RCRA facility permit arc available to technology ven-
dors and other laboratory or testing facilities for compli-
ance with these requirements: a Research, Development,
and Demonstration (RD&D) permit, which covers limited-
duration and limited-quantity tcsiing of actual hazardous
wasic, and the ucalability exclusion under RCRA, which
may exempt small-scale icsting activities from certain RCRA
permitting requirements.*
Research, Development, and Dcmonairaiion Permits
Hazardous waste treatment facilities thai propose to use an
innovative and experimental ircaimcm technology or pro-
cess for which RCRA permit siandards have not been
promulgated under Pan 264 or 266 may obtain an RD&D
permit (40 CR 270.65). This provision is imcndcd 10
expcdilc the permit review and issuance process.
An RD&D permit may be required for laboratories or
testing facilities that perform pilot-scale tests lhat arc likely
lo exceed ihe sioragc and treatment rair limits specified
under the trcatability exclusion. Limitations on the lypcs
and quantities of hazardous waste lhai can be received and
ircatcd by the facilily under an RD&D permit and the
requirements for icsting, reporting, and protection of hu-
man health and the environment (as deemed necessary by
ihc Agency) arc specified in ihc icrms and condiiions of ihc
pcrmii. The RD&D pcrrniis arc issued for a period of 1
year and may be renewed up 10 ihrcc limes for one addi-
tional year each.
The suuus of ihc RD&D permit authority in a particular
State can be determined by contacting the appropriate
Region's RCRA Coordinator for that Slate.
*The Agency intends to address large-scale trcaiabiliiy
studies in separate rulcmaking ai some fuiurc date; the
Agency also is considering developing rcgulalions under
40 CFR Part 264, Subpart Y, thai would establish pcrmit-
ling standards for experimental facilities conduciing re-
search and dcvclopmcni on the sioragc, ircatmcm, or dis-
posal of hazardous wasic.
41
-------
Will
trettability study be
conducted on site or
off site?
Do the
Federal treatability
study sample exemption rule in
40 CFR 261.4(e) and (I) (or equivalenl
State regulations) or other exclusions
in 40 CFR 261.4(b)
apply1?
Will quantity
of 'as received" waste
subjected to initiation of treatment
in any single day exceed
250 kg?
Will quantity
of "as received" waste
stored at the facility for purposes
of testing exceed
1000-kg?
No Federal, State, or local permits
required |40 CFR 300.400(e)(l)|;
however, facility must comply with
applicable or relevant and
appropriate requirements under
Federal and State environmental
laws to the extent practicable (or
justify a waiver).
Subject to regulation under
appropriate Federal and State
environmental laws and the
Revised Off-Site Policy (OSWER
Directive 9834.11).
No
Conditionally exempt from RCRA treatment,
storage, and permitting requirements set forth
in 40 CFR Parts 264, 265, and 270 provided
notification, recordkeeping, and reporting
requirements are met [40 CFR 261.4(1)].
Facility must comply with Revised Off-Site
Policy (OSWER Directive 9834.11).
Figure 8. Facility requirements for treatability testing.
42
-------
Do the
Federal treatability
'study sample exemption rule in"
40 CFR 261.4(e) and (f) (or equivalent
State regulations) or other exclusions,
in 40 CFR 261.4(b)
apply?
Yes
Will quantity of
sample shipment exceed'
1000 kg of nonacute hazardous
waste. 1 kg of acute hazardous waste,
^or 250 kg of soils, water, or debris^
contaminated with
.acute hazardous^
No
Subject to regulation under
appropriate Federal and State
environmental laws and the
Revised Off-Site Policy (OSWER
Directive 9834.11).
Conditionally exempt from RCRA generator
and transporter requirements set forth in 40
CFR Parts 262 and 263 provided
recordkeeping and reporting requirements
are met [40 CFR 261.4(e)].
Figure 9. Shipping requirements for oftslte treatability testing.
Treatabiliry Exclusion
Effective July 19,1988, the sample exclusion provision [40
CFR 261.4(d)], which exempts waste samples collected for
the sole purpose of determining their characteristics or
composition from regulation under Subtitle C of RCRA,
was expanded to include waste samples used in small-scale
treatability studies (53 FR 27301). Because it is considered
less stringent than authorized State regulations for RCRA
permits, the Federal Treatability Study Sample Exemption
Rule is applicable only in those States that do not have final
authorization or in authorized Suites that have revised their
program to adopt equivalent regulations under State law.
Although the provision is optional, the EPA has strongly
encouraged authorized States to adopt the exemption or 10
exercise their authority to order instability studies (in case
of imminent and substantial cndangcrmcnt to health or the
environment) or to grant a general waiver, permit waiver.
or emergency permit authority to authorize trealability stud-
ies. The status of the ircaiability exclusion in a parucular
State can be determined by contacting the appropriate
Region's RCRA Coordinator for that State.
Under the ireatabilily exclusion, persons who generate or
collect samples of hazardous waste (as defined under RCRA)
for the purpose of conducting trcalability studies arc condi-
tionally exempt from the generator and transporter require-
ments (40 CFR Parts 262 and 263) when the samples arc
being collected, stored, or transported to an offsite labora-
tory or testing facility [40 CFR 261.4(c)] provided that:
1) The generator or sample collector uses no more
lhan 1000 kg of any nonacutc ha/ardous waste, 1
kg of acute hazardous waste, or 250 kg of soils,
water, or debris contaminated with acute hazard-
ous waste per waste stream per treatment process.
43
-------
On a casc-by-casc basis, the Regional Adminis-
trator or State Director may grant requests for
waste stream limits up to an additional 500 kg of
nonacute hazardous waste. 1 kg of acute hazard-
ous waste, and 250 kg of soils, water, or debris
contaminated with acute hazardous waste.
2) The quantity of each sample shipment docs not
exceed these quantity limitations.
3) The sample is packaged so that it will not leak,
spill, or vaporize from its packaging during ship-
ment, and the transportation of each sample ship-
ment complies with U.S. Dcpartmeni of Trans-
portation (DOT), U.S. Postal Sen-ice (USPS), or
any other applicable regulations for shipping haz-
ardous materials.
4) The sample is shipped to a laboratory or testing
facility that is exempt under 40 CFR 261.4(0 or that
has an appropriate RCRA permit or interim status.
5) The generator or sample collector maintains cop-
ies of the shipping documents, the contract with
the facility conducting the ircaiabiliiy study, and
records showing compliance with the shipping limits
for 3 years after completion of the treaiabilily study.
6) The generator provides the preceding documenta-
tion in its biennial report.
Similarly, offsilc laboratories or testing facilities (includ-
ing mobile treatment units) arc conditionally exempt from
the treatment, storage, and permitting requirements (40
CFR Parts 264,265, and 270) when conducting ircaiabiliiy
studies [40 CFR 261.4(f)] provided that:
1) The facility notifies the Regional Administrator or
Slate Director that it intends to conduct trcaiability
studies.
2) The laboratory or testing facility has an EPA iden-
tification number.
3) The quantity of "as received" hazardous waste
that is subjected to initiation of treatment in all
instability studies in any single day is less than
250kg.
4) The quantity of "as received" hazardous waste
stored at the facility docs not exceed 1000 kg,
which can include 500 kg of soils, water, or debris
contaminated with acute hazardous waste or 1 kg
of acuie hazardous waste.
5) No more than 90 days have elapsed since ihe
trcatability study was completed, or no more than
1 year has elapsed since the gcncraior or sample
collector shipped the sample to the laboratory' or
testing facility.
6) The treatability study involves neither placement
of hazardous waste on the land nor open burning
of hazardous waste.
7) The facility maintains records showing compli-
ance wilh the ircatment rate limits and the storage
lime and quantity limits for 3 years following
completion of each study.
8) The facility keeps a copy of Uic ircatability study
contract and all shipping papers for 3 years after
the completion date of each study.
9) The facility submits to the Regional Administra-
tor or Stale Director an annual report estimating
ihe number of studies and the amount of waste to
be used in ircaiability studies during the current
year and providing informauon on trcaiability stud-
ies conducted during ihe preceding year.
10) The facility determines whether any unused sample
or residues generated by the trcatabilily study arc
hazardous waste [unless they arc returned to the
sample originator under the 40 CFR 261.4(c) ex-
emption].
11) The facility notifies the Regional Administrator or
State Director when it is no longer planning to
conduct any instability studies at the site.
Laboratories or testing facilities lhai perform bench-scale
tests generally meet the storage and ircatment rale limits
outlined in the preceding items. Faciliiics noi operating
within these limiiaiions arc subject to appropriate regula-
tion.
3.9.3 Residuals Management
Treaiabilily study residuals generated at an offsilc labora-
tory or testing facility may be rciurncd 10 the sample origi-
nator under ihe Federal Trcatabilily Study Sample Exemp-
tion Rule (or equivalent State regulations) if the storage
lime limits in 40 CFR 261.4(0 arc not exceeded. This
includes any unused sample or residues. If the cxcmpiion
docs not apply, Ihe disposal of treaiabilily study residuals is
subject to appropriate regulation, including the RCRA land
disposal restrictions for contaminated soil and debris when
these regulations become cffcciivc. Trcauibiliiy siudy re-
44
-------
siduals managed offsile must be packaged, labeled, and
manifested in accordance with 40 CFR Pan 262 and appli-
cable DOT regulations for hazardous materials under 49
CFR Part 172.
As discussed earlier, the Revised Off-Site Policy does not
specifically exempt the transfer of treatability study residu-
als offsile for disposal; therefore, offsile treatment or dis-
posal facilities that receive these wastes must be in compli-
ance with the offsite requirements. The acceptability of a
commercial facility for receiving CERCLA wastes can be
determined by contacting the appropriate Regional Offsile
Contact, as shown in Table 12.
Table 12. Regional Offsite Contacts for
Determining Acceptability Of Commercial
Facilities to Receive CERCLA Wastes"
Region
Primary
contact/phone
Backup
contact/phone
I Lin Hanifan
(617)573-5755
II Gregory Zaccardi
(212)264-9504
III Naomi Henry
(215)597-8338
IV Alan Antley
(404) 347-4450
V Gertrude Maluschkovitz
(312)353-7921
VI Trish Brechlin
(214)655-6765
VII David Doyle
(913)236-2891
VIII Felix Fiechas
(303)293-1524
IX Diane Bodine
(415)744-2130
X Al Odmark
(206)553-1886
Robin Biscaia
(617)573-5754
Joe Golumbek
(212)264-2638
John Gorman
(212)264-2621
Rita Tale
(215)597-8175
Gregory Fraley
(404) 347-7603
Paul Dimock
(312)886-4445
Randy Brown
(214)655-6745
Marc Rivas
(913)236-2891
Mike Gansecki
(303)293-1510
Terry Brown
(303)293-1823
Jane Diamond
(415)744-2139
Ron Lillich
(206) 553-6646
aThese contacts are subject to change.
3.10 Executing the Study
Execution of the trcatability study begins after the project
manager has approved the Work Plan and other supporting
documents. Steps include collecting a sample of the waste
stream for characterization and testing, conducting the test.
and collecting and analy/ing samples of the treated waste
and residuals.
3.10.1 Field Sampling and Waste
Stream Characterization
Field samples should be collected and preserved in accor-
dance with the procedures outlined in the SAP. They
should be representative of either "average" or "worst-
case" conditions (as dictated by the test objectives), and the
sample should be large enough 10 complete all of the re-
quired tests and analyses in the event of some anomaly.
Collocated field samples also should be collected in accor-
dance with the QAPP. To the extent possible, field sam-
pling should be coordinated wiih oihcr onsile activities to
minimize costs. Samples shipped to an offsile laboraiory
for icsu'ng or analysis must be packaged, labeled, and
shipped in accordance with DOT, USPS, or other applicable
shipping regulations (sec Subsection 3.9). A chain-of-
custody record must accompany each sample shipment.
The waste sample should be thoroughly mixed to ensure
that it is homogeneous. This permits a comparison of
results under different test conditions. Small-volume soil
samples can be mixed with a Hobart mixer, and large-
volume samples can be mixed with a drum roller. Stones
and debris should be removed by screening. Care must be
exercised during these procedures to avoid contaminating
the waste samples (or allowing volatiles to escape) and to
ensure effective homogcnizaiion.
Characterization samples should be collected from the same
material that will be used in the performance of the
treatability study. Characterization is necessary to deter-
mine the chemical, physical, and/or biological properties
exhibited by the waste stream so that the results of the
ircatability study can be properly gauged.
3.10.2 Treatability Testing
The treatability study should be performed in accordance
with the test matrix and standard operating procedures
described in the Work Plan. Any deviations from the SOP
should be recorded in the field or laboratory notebook.
The EPA or a qualified contractor should oversee testing
conducted by vendors and PRPs. Oversight activities were
discussed in Subsection 2.5.5.
3.10.3 Sampling and Analysis
Samples of ihc treated waste and process residuals (e.g.,
off-gas, scrubber water, and ash for incineration tests) should
be collected in accordance with the SAP. The SAP spcci-
45
-------
fies the location and frequency of sampling, proper con-
tainers, sample preservation techniques, and maximum hold-
ing times. Quality assurance/quality control samples will
be collected at the same time as the trcatability study samples
in accordance with the QAPP. All samples must be logged
in the field or laboratory notebook. Samples shipped to an
offsite laboratory must be packaged, labeled, and shipped
in accordance with DOT, USPS, or other applicable ship-
ping regulations, and a chain-of-custody record must ac-
company each sample shipment.
Treatability study samples should be analyzed in accor-
dance with the methods specified in the SAP. Normal
sample turnaround lime is 3 to 5 weeks for most analyses;
the laboratory may charge a premium if results are required
in less lime.
3.11 Analyzing and Interpreting the
Data
3.17.1 Data Analysis
Upon completion of a treatability study, the data must be
compiled and analyzed. The first goal of data analysis is to
determine the quality of the data collected. All data should
be checked to assess precision, accuracy, and complete-
ness. Both testing and analytical error must be assessed to
determine total error. If the QA objectives specified in the
QAPP have not been met, the project manager and the EPA
Work Assignment Manager must determine the appropri-
ate corrective action.
Data are generally summarized in tabular or graphic form.
The exact presentation of the data will depend on the
experimental design and the relationship between the vari-
ables being compared. For data presented graphically,
independent variables, which arc controlled by the experi-
menter, are generally plotted on the abscissa; whereas depen-
dent variables, which change in response to changing the
independent variables, are plotted on the ordinate. Ex-
amples of independent variables are pH, temperature, re-
agent concentration, and reaction time. Examples of de-
pendent variables are removal efficiency and substrate uti-
lization.
For determining whether statistically significant differences
in treatment effectiveness exist between two or more val-
ues of an independent variable, the use of analysis of
variance and other statistical techniques may be appropri-
ate. These techniques can assist in identifying the most
cost-effective combination of parameters in a treatment
system with multiple independent variables. Statistical
analysis of treatability study data, however, should only be
performed when planned and budgeted for.
3.11.2 Data Interpretation/Pre-ROD
Interpretation of treatability study data must be based on
the test objectives established prior to testing. Data inter-
pretation is an important pan of the ircatability study re-
port. Therefore, the contractor or other parly performing
the sludy and preparing ihe report must fully understand the
study objectives and the role the results will play in remedy
screening, selection, or implementation. The investigating
party, not ihe RPM, is responsible for inierprciing ihc
ireatability sludy data.
The purpose of a pre-ROD ircatability invesiigation is to
provide ihe daia needed for a detailed analysis of alterna-
tives and, ultimately, the selection of a remedial action that
can achieve the site cleanup criteria. The results of a
trcatability sludy should enable the RPM to evaluate ull
ircaimem alternatives on an equal basis during the detailed
analysis of alternatives.
The Work Plan outlines ihe ircatability study's test objec-
tives and describes how these objectives will be used in the
evaluation of the technology (i.e., remedy screening or
remedy selection). As discussed in Section 2, the 1990
revised NCP Section 300.430(c) specifies nine evaluation
criteria 10 be considered in ihe assessment of remedial
alternatives. These criteria were developed to address both
ihe specific statutory requirements of CERCLA Section
121 (threshold criteria) and the icchnical and policy consid-
erations that are important in ihe selection of remedial
alternatives (primary balancing criteria and modifying cri-
teria). The nine RI/FS evaluation criteria arc as follows:
Threshold criteria:
• Overall proicction of human health and ihc
environment
• Compliance with ARARs
Primary balancing criteria:
• Long-icrm effectiveness and permanence
• Reduction of toxicity, mobility, and volume ihrough
treatment
• Short-term effectiveness
• Implcmcntability
• Cost
Modifying criteria:
• State acceptance
• Community acceptance
46
-------
As discussed in the following subsections, ircatability stud-
ies provide important data for use in the assessment of an
alternative against both the threshold criteria and the pri-
mary balancing criteria. The results of treaiability studies
can also influence evaluations against the State and com-
munity acceptance criteria. Figure 10 lists factors impor-
tant to the analysis of the Rl/FS evaluation criteria. These
factors arc often technology-specific, as arc the treatability
study data that support the analysis of each factor. Example 5
outlines some of the specific analysis factors applicable to
chemical dchalogcnation treatment technologies and several
types of data from a chemical dchalogenation trcatability
study that provide information for each of these factors
Evaluations against the nine criteria are performed for the
overall alternative, of which the treatment technology is
only a pan. The alternative will generally include additional
treatment, containment, or disposal technologies. Detailed
guidance on the Super!und program's remedy-selection
process as established in the 1990 revised NCR Section
300.430(0 is available in the Rl/FS guidance and in A
Guide to Selecting Supcrfund Remedial Actions (EPA 1990b).
Threshold Criteria
The two statutory-based threshold criteria should be used
to set instability study performance goals. Only those
alternatives that satisfy the threshold criteria arc eligible for
remedy selection.
Overall Protection of Human Health and the Environment
This evaluation criterion provides an overall assessment of
how well each alternative achieves and maintains protec-
tion of human health and the environment. The analysis of
overall protection will draw on the assessments conducted
under the primary evaluation criteria and the compliance
with ARARs. It will focus on the ability of an alternative to
eliminate, reduce, or control overall site risks.
Trcatabilily studies will provide general data for the evalu-
ation under this criterion. Target contaminant concentrations
in the treated product and any treatment residuals will dem-
onstrate how well the process or treatment train can eliminate
site risks. If an ecological risk assessment is being con-
ducted, bioassessmcnts of these materials will generate the
data required to evaluate the reduction in risk to site biota.
Compliance with ARARs
Applicable or relevant and appropriate requirements arc
any local. State, or Federal regulations or standards that
pertain to chemical contaminant levels, locations, and ac-
tions at CERCLA sites. Trcatabilily study performance
goals are generally based on ARARs. Performance data
indicaung how well the process achieved these goals will
aid in evaluating the technology against the compliance
with ARARs criterion.
Chemical-specific ARARs arc health or risk-based numeri-
cal values or methodologies that, when applied to site-
specific conditions, result in the establishment of maxi-
mum acceptable amounts or concentrations of chemicals
that may be found in or discharged to the ambient environ-
ment. For example, chemical-specific ARARs may in-
clude RCRA Land Disposal Restrictions (LDRs) on the
placement of treated soil or Safe Drinking Water Act Maxi-
mum Contaminant Levels (MCLs) and Clean Water Act
Water Quality Criteria for the treatment and discharge of
wastcwatcr. Chemical-specific ARARs will be expressed
in terms of contaminant concentrations in the treated prod-
uct and treatment residuals. Often, these ARARs define the
"target" contaminants for the trcauibility study.
Location-specific ARARs arc restrictions placed on the
concentration of hazardous substances or the conduct of
activities solely because they arc in a specific location,
such as a floodplain, a wetland, or a historic place. Loca-
tion-specific cleanup criteria may include, for example,
biotoxicity requirements for treated product and ircaimcnt
residuals if runoff from the ircaimcnt area or the disposal
site could have an impact on a sensitive wildlife habitat.
Action-specific ARARs arc technology- and activiiy-bascd
requirements or limitations on actions taken with respect to
hazardous wastes. Action-specific requirements may be
particularly applicable to the discharge of residuals such as
wastcwater. Target contaminant concentrations in the
ircatability study wastcwatcr will aid in identifying action-
specific ARARs.
The actual determination of which requirements arc appli-
cable or relevant and appropriate will be made by the lead
agency. Detailed guidance on determining whether re-
quirements are applicable or relevant and appropriate is
provided in CERCLA Compliance with Other Laws Manual:
Interim Final (EPA 1988c) and CERCLA Compliance with
Other Law Manual: Part II (EPA 1989Q.
Primary Balancing Criteria
The five primary balancing evaluation criteria should be
used for guidance in setting trcatabiliiy study test objectives.
Long-Term Effectiveness and Permanence
This evaluation criterion addresses risks remaining at the
site aflcr ihc remedial response objectives have been mci.
47
-------
Overall Protection of
Human Health and the
Environment
How Alternative Provides
Human Health and
Environmental Protection
Compliance With ARARs
Compliance With
Chemical-Specific ARARs
Compliance With Action-
Specific ARARs
Compliance With
Location-Specific ARARs
Compliance With Other
Criteria. Advisories, and
Guidances
Long-Term
Effectiveness and
Permanence
Reduction of Toxicity,
Mobility, or Volume
Through Treatment
Short-Term
Effectiveness
Implementability
Cost
Magnitude of
Residual Risk
Adequacy and
Reliability of
Controls
Treatment Process
Used and Materials
Treated
Amount of Hazardous
Materials Destroyed or
Treated
Degree of Expected
Reductions in Toxicity,
Mobility, and Volume
Degree to Which
Treatment Is Irreversible
Type and Quantity of
Residuals Remaining
Alter Treatment
Protection of
Community During
Remedial Actions
Protection of
Workers During
Remedial Actions
Environmental
Impacts
Time Until Remedial
Response
Objectives Are
Achieved
State
Acceptance'
Community
Acceptance*
Ability to Construct
and Operate the
Technology
Reliability of the
Technology
Ease of Undertaking
Additional Remedial
Actions. If
Necessary
Ability to Monitor
Effectiveness of
Remedy
Ability to Obtain
Approvals From
Other Agencies
Coordination With
Other Agencies
Availability of Offsite
Treatment, Storage,
and Disposal
Services and
Capacity
Availability of
Necessary
Equipment and
Specialists
Availability of
Prospective
Technologies
Capital Costs
Operating and
Maintenance
Costs
Present Worth
Cost
"These criteria are assessed following comment on the RI/FS report and the proposed plan.
EPA 1988a
Figure 10. Evaluation criteria and analysis factors lor detailed analysis of alternatives.
48
-------
EXAMPLE 5. APPLICABILITY OF CHEMICAL DEHALOGENATION TREATABILITY STUDY DATA
TO RI/FS EVALUATION CRITERIA
Evaluation Criteria
Analysis Factors
Treatability Study Data
Long-Term Effectiveness
and Permanence
Magnitude of residual risk
Target contaminant concentrations in
treated product and treatment
residuals
Presence of specific reaction
byproducts in treated product
Results of bioassays performed on
treated product
Reduction of Toxicity,
Mobility, or Volume
Through Treatment
Reduction in toxicity
Irreversibility of the treatment
Type and quantity of, and
risks posed by, treatment
residuals
Percent reduction in target
contaminant concentrations
Comparison of bioassay results
before and after treatment
Material balance data combined with
target contaminant concentrations in
treated product and treatment
residuals
Target contaminant concentrations in
treatment residuals
Presence of specific reaction
byproducts in treatment residuals
Results of bioassays performed on
treatment residuals
Volume of treatment residuals
Short-Term Effectiveness
Time until remedial response
objectives are achieved
Reaction time
Implementability
Reliability and potential for
schedule delays
Reliability and schedule delays curing
testing
Reaction time/throughput
Physical characteristics of waste
matrix
Contaminant variability in untreated
waste
Cost
Direct capital costs
Reaction time/throughput
Reagent usage/recovery
Reaction temperature
Physical characteristics of waste
matrix
Site characteristics
Compliance with ARARs Chemical-specific ARARs
Target contaminant concentrations in
treated product and treatment
residuals
Overall Protection of
Human Health and the
Environment
Ability to eliminate, reduce,
or control site risks
Target contaminant concentrations in
treated product and treatment
residuals
Presence of specific reaction
byproducts in treated product and
treatment residuals
Results of bioassays performed on
treated product and treatment
residuals
49
-------
Assessment of the residual risks from untreated waste and
treated product left on site must involve the same assump-
tions and calculation procedures as those used in the base-
line risk assessment. If engineered controls (e.g., contain-
ment systems) are to be used to manage these remaining
materials, their adequacy and reliability also should be
evaluated under this criterion.
Remedy-.1 election treatability studies can often provide data
on the site's post-remediation residual risk. If treated
product will remain on site, the contaminant concentrations
in this material must meet the site's cleanup criteria. As
discussed in Subsection 2.4, these cleanup criteria translate
into specific performance goals. The concentrations of
target contaminants in the treated product and treatment
residuals after treatability testing indicate the magnitude of
the site's residual risk after treatment.
If an ecological risk assessment is to be performed, the
residual risks posed to biota by the replacement of the
treated product on site can be assessed under this criterion.
The literature survey may provide adequate data to evalu-
ate the biotoxicity of treated soils. If the literature contains
little or no biotoxicity data on the contaminants/matrix of
interest, this data need can be addressed by performing
bioassays at the remedy-selection tier. A treatability study
test objective that stipulates a reduction in the loxicity of
the treated product to test organisms will provide data for
the assessment of the technology against the long-term
effectiveness and permanence criterion.
Reduction ofToxicity. Mobility, and Volume Through Treat-
ment
This evaluation criterion addresses the statutory preference
for selecting technologies that permanently and signifi-
cantly reduce the toxicity, mobility, or volume of the haz-
ardous substances. This preference is satisfied when treat-
ment is used to reduce the principal threats at a site through
destruction of toxic contaminants, reduction of the total
mass of toxic contaminants, irreversible reduction in con-
taminant mobility, or reduction of the total volume of
contaminated media.
Treatabilily studies should provide detailed performance
data on the percentage reduction in the toxicity, mobility,
or volume of the treated product As discussed in Subsec-
tion 2.4, a performance goal of greater than 50 percent
reduction in toxicity, mobility, or volume may be appropri-
ate at the remedy-screening tier. If this performance goal is
met, the technology is considered to be potentially feasible.
At the remedy-selection tier, the process should be capable
of achieving the site cleanup criteria with an acceptable
level of confidence. If no cleanup criteria have been estab-
lished for the site, a 90 percent reduction in contaminant
concentration will generally be an appropriate performance
goal.
Another measure of reduction in loxicity is the comparison
of bioassay results from tests performed on the waste be-
fore and after treatment. If treated product is to remain on
site, a reduction in biotoxicity should be identified as a
trcaiability test objective for remedy-selection testing.
Irreversibility of the treatment process is another factor in
the evaluation of a technology against this criterion. Mate-
rial balance data from a treatability study combined with
the target contaminant concentrations found in the treated
product and treatment residuals can indicate the level of
irreversibility achieved through treatment. These daui can
be used to construct a mass balance for the target contami-
nants, which will approximate the contaminant destruction
efficiency of the treatment process.
Taking the treatment residuals into consideration is an
important part of the assessment of a technology against the
reduction in toxicity, mobility, and volume criterion. Con-
centrations of target contaminants in ircatabilily study re-
siduals indicate the risks posed by onsitc treatment and
disposal of the process residuals. Data on the biotoxicity
and volume of ireatability study residuals also provide
information for this assessment.
Short-Term Effectiveness
The short-term effectiveness criterion is concerned with
the effects of the alternative on human health and the
environment during its construction and implementation.
The RI/FS guidance outlines several factors that may be
addressed, if appropriate, when assessing an alternative
against this criterion. Treatability studies can provide in-
formation on three of these factors: 1) protection of the
community during remedial actions, 2) protection of the
workers, and 3) lime required to achieve remedial response
objectives.
If a site is located near a population center, any short-term
health risks posed by the remedial aciion musi be ad-
dressed. The instability sludy wasic characterization can
idcnu'fy some of ihcsc risks. For example, physical charac-
icrisiics of the waste matrix, such as moisture content and
particle-size distribution, could indicate a potential for the
generation of contaminated dust during material-handling
operations. The presence of volatile contaminants in the
waste also could pose risks to community health during
material handling and treatment. Treatment residuals should
be carefully characterized to assist in the posuROD design
of proper air and water treatment systems.
50
-------
For the protection of workers during implementation of the
remedy, the phys.cal and chemical characteristics of the
untreated waste matrix and the treatment residuals are im-
portant data to be collected during treatability testing. These
data will aid in the assessment of any threats posed to
workers and the effectiveness and reliability of the protec-
tive measures to be taken. Treatability systems can also be
monitored for any adverse conditions thai may develop
during testing.
The time required to achieve the remedial response objec-
tives for the site depends on the volume of soil to be treated
and the throughput of the full-scale unit or treatment train
system. Treatability studies of some technologies will
generate treatment duration data sufficient to allow esti-
mates of throughput to be made.
Implemeniabiliiy
This evaluation criterion assesses the technical and admin-
istrative feasibility of implementing an alternative and the
availability of the equipment an'! services required during
implementation. The process of designing and performing
treatability studies may assist in the analysis of the follow-
ing implementability factors:
• Difficulties associated with construction and operation
• Reliability and potential for schedule delays
• Ability to monitor treatment effectiveness
• Commercial availability of the treatment process and
equipment
The literature survey should provide historical information
regarding most of the preceding factors. If an alternative
has been shown to be capable of achieving the desired
cleanup levels but has never been demonstrated at full
scale, reliability data may be insufficient for its assessment
under the implementability criterion. In this case, data
from a pre-ROD pilot-scale test may be required.
The reliability of the pilot system, including any schedule
delays encountered during its testing, will serve as an indi-
cator of the implementability of the full-scale system. The
treatment duration and throughput can also provide infor-
mation on potential schedule delays. Characteristics of the
matrix that could lead to equipment failure or diminished
treatment effectiveness, such as high clay content, can be
investigated during a prc-ROD treatability study. Con-
taminant variability in the untreated waste could also lead
to schedule delays by requiring repeated treatment of some
soils. Treatability testing of multiple waste types with
differing contaminant concentrations can provide impor-
tant data for analysis of the reliability factor and the imple-
mentability evaluation criterion.
Cost
The cost criterion evaluates the full-scale capital and opera-
lion and maintenance (O&M) costs of each remedial action
alternative. The assessment of this criterion requires the
development of cost estimates for the full-scale remedia-
tion of the site. These estimates should provide an accu-
racy of +50 percent to -30 percent. A comprehensive
discussion of costing procedures for CERCLA sites is in-
cluded in Remedial Action Costing Procedures Manual
(EPA 1,985). The cost estimate prepared under this crite-
rion will be based on information obtained from the litera-
ture and from technology vendors. Preparation of the
estimate may also require remedy-selection instability study
data.
Direct capital costs for treatment will include expenditures
for the equipment, labor, and materials necessary to install
the system. If the technology vendor has already con-
structed a mobile, full-scale treatment unit, treauibility study
data will not be required to determine direct equipment
costs. If no full-scale system exists, however, trcatabiliiy
studies can provide the .operational data necessary for equip-
ment scale-up. Characteristics of (he matrix identified
during treatabilily testing, such as particle-size distribution
and moisture content, will have an impact on decisions
regarding front-end material handling operations and equip-
ment and post-treatment equipment for processing of the
product and residuals in a treatment train. Characteristics
of the site that may have an. impact on the logistical costs
associated with mobilization and onsitc treatment can be
identified during the ircatabiliiy study sample-collection
visit.
Estimates of utility costs, residuals treatment and disposal
costs, and O&M costs will depend on the physical/chemi-
cal characteristics of the waste and residuals (which affect
the difficulty of treatment) and the throughput (which af-
fects the total time for treatment). These data arc available
from remedy-selection treatability studies.
3.11.3 Data Interpretation/Post-ROD
As opposed to pre-ROD trcauibility studies, no clearly
defined criteria exist on which to base the interpretation of
post-ROD RD/RA trcatability study results. The purpose
of an RD/RA trcaiability study is to generate specific,
detailed design, cost, and performance data. These data arc
then used 1) to prcqualify vendors and processes within the
prescribed remedy, 2) to implement the most appropriate of
51
-------
the remedies prescribed in a Contingency ROD, or 3) to
support preparation of the Agency's detailed design speci-
fications and the design of treatment trains.
When an RD/RA treatability study is performed to prequalify
vendors, data interpretation consists of a straightforward
determination by the lead agency or the designer regarding
whether the vendor has attained the preset performance
goals. Little or no cost data are generated by prequalification
treatability studies. Based on these results, the lead agency
determines which vendors are qualified to bid on the RA.
Generally, the vendor should achieve results equivalent to
the cleanup criteria defined in the ROD to be considered for
prequalification.
In the case of a Contingency ROD, implementation of the
selected remedy may depend on the results of RD/RA
treatability testing. Treatability studies performed to sup-
port a Contingency ROD are designed to obtain perfor-
mance and cost data on the selected remedy that were not
available during the RI/FS. After this information is ob-
tained, data interpretation focuses on determining whether
the selected remedy will provide superior protection of
human health and the environment at a cost comparable to
that of the contingency remedy. If so, the selected remedy
is designed and implemented. If not, the contingency
remedy is implemented.
Post-ROD treatability study results are also used to sup-
port the preparation of the detailed design specifications
and the design of treatment trains. Because the treatability
study is designed to provide specific detailed operations
data on the remedy for use by the remedial design contrac-
tor, the designer is generally responsible for data interpre-
tation.
3.12 Reporting the Results
3.12.1 General
The final step in conducting a treatability study is reporting
the lest results. Complete and accurate reporting is critical,
as decisions about treatment alternatives will be based
partly on the outcome of the treatability studies. Besides
assisting in the selection and implementation of the rem-
edy, the performance of treatabiliiy studies will increase
the existing body of scientific knowledge about treatment
technologies.
To facilitate the reporting of ireatability study results and
the exchange of treatment technology information. Table 13
presents a suggested organization for a treatability study
report. Reporting ireatability study results in this manner
will expedite the process of comparing treatment alterna-
tives. It will also allow other individuals who may be
studying similar technologies or waste matrices to gain
valuable insight into the applications and limitations of
various treatment processes.
If a treatment technology is to be tested at multiple tiers,
preparau'on of a formal report for each tier of the testing
may not be necessary. Interim reports prepared ai the
completion of each tier may suffice. Also, it may be
appropriate to conduct a project briefing with the interested
panics to present the study findings and to determine the
need for additional testing. A final report that encompasses
the entire study should be developed after all testing is
complete.
As an aid in the seleciion of remedies and the planning of
future treatability studies, the Office of Emergency and
Remedial Response requires that a copy of all treatability
study reports be submitted to the Agency's RREL Treat-
abilily Data Base repository, which is being developed by
the ORD (EPA 1989e). This requirement applies to both
the removal and remedial programs of Superfund. Submit-
ting treatability study reports in accordance with the sug-
gested organization will increase the usability of this re-
pository' and assisi in maintaining and updating the data
base. One camera-ready master copy of each treatability
study report should be sent to the following address:
Mr. Glenn M. Shau)
RREL Treatability Data Base
U.S. Environmental Protection Agency
Office of Research and Development
Risk Reduction Engineering Laboratory
26 W. Martin Luther King Drive
Cincinnaii, Ohio 45268
The following subsections describe the contents of the
treatabilily study report.
Introduction
The introductory section of the treatability study report
contains background information about the site, waste
stream, and treatment technology. Much of this informa-
tion will come directly from the previously prepared
ireatability study Work Plan. This section also includes a
summary of any treatabilily siudies previously conducted
at the site.
Conclusions and Recommendations
This seciion of the repon presents the conclusions and
recommendaiions regarding the applicability of the treat-
52
-------
Table 13. Suggested Organization of
Treatability Study Report
1. Introduction
1.1 Site description
1.1.1 Site name and location
1.1.2 History of operations
1.1.3 Prior removal and remediation
activities
1.2 Waste stream description
1.2.1 Waste matrices
•1.2.2 Pollutants/chemicals
1.3 Treatment technology description
1.3.1 Treatment process and scale
1.3.2 Operating features
1.4 Previous treatability studies at the site
2. Conclusions and Recommendations
2.1 Conclusions
2.2 Recommendations
3. Treatability Study Approach
3.1 Test objectives and rationale
3.2 Experimental design and procedures
3.3 Equipment and materials
3.4 Sampling and analysis
3.4.1 Waste stream
3.4.2 Treatment process
3.5 Data management
3.6 Deviations from the Work Plan
4. Results and Discussion
4.1 Data analysis and interpretation
4.1.1 Analysis of waste stream
characteristics
4.1.2 Analysis of treatability study data
4.1.3 Comparison to test objectives
4.2 Quality assurance/quality control
4.3 Costs/schedule for performing the
treatability study
4.4 Key contacts
References
Appendices
A. Data summaries
B. Standard operating procedures
ment process tested. It should aucmpi 10 answer questions
such as the following:
• Were the performance goals met? Were the other test
objectives achieved? If not, why not?
• Were there any problems with the treatability study
design or procedures?
• What parts of the test (if any) should have been per-
formed differently? Why?
• Are additional tiers of trcatability testing required for
further evaluation of the technology? Why or why
not?
• Are data sufficient for adequately assessing the tech-
nology against the Rl/FS evaluation criteria (if prc-ROD)?
• Are data sufficient for designing and implementing the
remedy (if post-ROD)?
The conclusions and recommendations should be stated
briefly and succinctly. Information that is pertinent to the
discussion and exists elsewhere in the rcpon should be
referenced rather than restated in this section.
This section should provide an analysis of the results as
they relate to the objectives of the study and the relevant
evaluation criteria. When appropriate, the results should be
extrapolated to full-scale operation to indicate areas of
uncertainty in the analysis and the extent of this uncertainly.
Treatability Study Approach
This section reports why and how the trcaiability study was
conducted. It describes in detail the procedures and meth-
ods that were used to sample and analyze the waste stream
and documents any deviations from the Work Plan. Like
the introduction, this section contains information from the
previously prepared Work Plan.
Results and Discussion
The final section of the trcatability study report includes the
presentation and a discussion of results (including QA/
QC). Results for the contaminants of concern should be
reported in terms of the concentration in the input and
output streams and the percentage reduction in toxicity,
mobility, or volume that was achieved. The use of charts
and graphs may aid in the presentation of these results.
This section also includes the costs and time required to
conduct the study and any key contacts for future reference.
Appendices
Summaries of the data generated and the standard operat-
ing procedures used arc included in appendices.
3.12.2 Remedy Screening
Remedy screening results will be reported in the format
shown in Table 13; however, some of the sections mav be
53
-------
abbreviated if remedy-selection lesung is planned. The
conclusions and recommendations will focus primarily on
whether the technology investigated is potentially feasible
for the site and will attempt to identify critical parameters
for future treatability testing. Data will be presented in
simple tables or graphs. Statistical analysis is generally not
required. Because remedy screening does not involve rig-
orous QA/QC, the discussion of this subject will be brief.
3.12.3 Remedy-Selection Testing
Conclusions and recommendations resulting from remedy-
selection testing will focus primarily on the technology's
performance (i.e., ability to meet the performance goals
and test objectives) and will attempt to identify critical
parameters for future treatability testing, if needed. A
detailed discussion of data quality should be included in the
results section. The results section may also include a
statistical evaluation of the data.
3.72.4 RD/RA Testing
Conclusions and recommendations resulting from RD/RA
testing will focus on the technology's ability to achieve the
performance goals and test objectives. Any process opti-
mization parameters that were identified should also be
discussed. The results should include a detailed discussion
of data quality.
54
-------
REFERENCES
dcPercin, P., E. Bales, and D Smith. 1991. Designing
Treaiability Studies for CERCLA Sites: Three Critical
Issues. J. Air Waste Manage. Assoc., 41(5):763-767.
National Institute for Occupational Safely and Health/Oc-
cupational Safely and Health Adminisiration/U.S. Coast
Guard/U.S. Environmental Protection Agency. 1985. Oc-
cupational Safety and Health Guidance Manual for Haz-
ardous Waste Site Activities. DHHS (N10SH) Publication
No. 85-115.
U.S. Environmental Proteciion Agency. 1980. Inierim
Guidelines and Specificaiions for Preparing Quality Assur-
ance Projcci Plans. QAMS-005/80.
U.S. Environmental Proiection Agency. 1985. Remedial
Action Costing Procedures Manual. EPA/600/8-87/049.
OSWER Directive No. 9355.0-10.
U.S. Environmental Protection Agency. 1986. Test Meth-
ods for Evaluating Solid Wasie. 3rdcd. SW-846.
U.S. Environmental Proteciion Agency. 1987a. Daia Qual-
ity Objccuves for Remedial Response Activities. Develop-
ment Process (Volume I). EPA/540/G-87/003, OSWER
Directive 9355.0-7B.
U.S. Environmental Proteciion Agency. 1987b. A Com-
pendium of Supcrfund Field Operations Methods. EPA/
540/P-87/001.
U.S. Environmental Proteciion Agency. 1987c. Revised
Procedures for Implemeniing Off-Site Response Actions.
OSWER Directive No. 9834.11, November 13,1987.
U.S. Environmental Protection Agency. 1988a. Guidance
for Conducting Remedial Investigations and Feasibility
Siudies Under CERCLA. Interim Final. EPA/540/G-89/
004. OSWER Directive 9355.3-01.
U.S. Environmental Protection Agency. 198Sb. Commu-
nity Relations in Supcrfund: A Handbook. Interim Ver-
sion. EPA/540/G-88/002. OSWER Directive 9230.0-3B.
U.S. Environmental Proteciion Agency. 1988c. CERCLA
Compliance with Olhcr Laws Manual: Interim Final. EPA/
540/G-89/006.
U.S. Environmental Proteciion Agency. 1989a. Managc-
mcni Review of ihc Supcrfund Program. EPA/540/8-89/
007.
U.S. Environmenial Protection Agency. 1989b. Guide for
Conducting Treaiabiliiy Studies Under CERCLA. Interim
Final. EPA/540/2-89/058.
U.S. Environmental Protection Agency. 1989c. Model
Staiemcnt of Work fora Remedial Investigation and Feasi-
bility Sludy Conducted by Potentially Responsible Parties.
OSWER Directive No. 9835.8, June 2, 1989.
U.S. Environment! Proicction Agency. 1989d. Quality
Assurance Procedures for KREL. RREL Document Con-
trol No. RREL(QA)-001/89.
U.S. Environmcntal Proicciion Agency. 1989c. Treaiabil-
ity Studies Coniracior Work Assignments. Memo from
Henry L. Longest, II, Dirccior, Office of Emergency and
Remedial Response, 10 Supcrfund Branch Chiefs, Regions
I ihrough X. OSWER Directive 9380.3-01, July 12, 1989.
U.S. Environmental Proicciion Agency. 1989f. CERCLA
Compliance wiih Olhcr Laws Manual: Pan II. Clean Air
Aci and Olher Environment! Siaiutes and Stale Require-
ment EPA/540/G-89/009. OSWER Directive No. 9234.1-02.
U.S. En vironmenial Proicciion Agency. 1990a. Inventory
of Treaiabiliiy Sludy Vendors, Volumes 1 and II. EPA/
540/2-90/003a and b.
55
-------
U.S. Environmenial Protection Agency. 1990b. A Guide U.S. Environmental Protection Agency. 1991b. Guidance
to Selecting Superfund Remedial Actions. OSWER Direc on Oversight of Potentially Responsible Party Remedial
live 9355.0-27FS. Investigations and Feasibility Studies. Volume 1. EPA/
540/G-91/010a. OSWER Directive No. 9835. l(c).
U.S. Environmental Protection Agency. 1991a. Guidance
for Increasing the Application of Innovative Treatment U.S. Environmental Protection Agency. 199lc. Administra-
Technologies for Contaminated Soil and Ground Water. live Order on Consent for Remedial Investigation/Feasibility
OSWER Directive 9380.0-17, June 10,1991. Study. OSWER Directive No. 98353-2A, July 2,1991.
56
-------
APPENDIX A
SOURCES OF TREATABILITY INFORMATION
A wide range of technical resources exists within the EPA
to assist in the planning and performance of treaiability
studies. These resources include reports and guidance
documents, electronic dam bases, and Agency-sponsored
technical support. This appendix describes the primary
treaiability study resources currently available.
Reports and Guidance Documents
Knowledge gained during the performance of treaiability
studies is available in reports and technical guidance docu-
ments. The following documents can be used to identify
technology-specific treaiability resources.
Superfund Treatability Clearinghouse Abstracts. U.S.
Environmental Protection Agency, Office of Emer-
gency and Remedial Response, Washington, DC. EPA/
540/2-89/00 I.March 1989.
Inventory of Treatability Study Vendors, Volumes I
and II. U.S. Environmental Protection Agency, Office
of Emergency and Remedial Response, Washington,
DC. EPA/540/2-90/003a and b, February 1990.
The Superfund Innovative Technology Evaluation Pro-
gram: Technology Profiles. U.S. Environmental Pro-
tection Agency, Office of Solid Waste and Emergency
Response and Office of Research and Development,
Washington, DC. EPA/540/5-90/006, November 1990.
Guide to Treatment Technologies for Hazardous Wastes
at Superfund Sites. U.S. Environmental Protection
Agency, Office of Solid Waste and Emergency Re-
sponse, Washington, DC. EPA/540/2-89/052, March
1989.
Treatabilily Potential for EPA Listed Hazardous Wastes
in Soil. U.S. Environmental Protection Agency, Of-
fice of Research and Development, Ada, OK. EPA/
600/2-89/01 I.March 1989.
Catalog of Superfund Program Publications. U.S. En-
vironmental Protection Agency, Office of Emergency
and Remedial Response, Washington, DC. EPA/540/
8-90/015, October 1990.
Electronic Information Systems
Several electronic data bases and information systems arc
available to Federal, Slate, and private sector personnel for
retrieving innovative technology and ircatability data.
RREL Treatability Data Base
Contact: Glenn Shaul
Risk Reduction Engineering Laboratory
Office of Research and Development
U.S. Environmental Proicciion Agency
(513)569-7408
Developed by ihe Risk Reduction Engineering Laboratory
(RREL), this data base provides dam on the ircaiability of
contaminants in water, soil, debris, sludge, and sediment.
Target users include Federal and State agencies, acadcmia,
and the private sector. For each contaminant, the data base
provides physical/chemical properties and treatabiliiy data
such as technology types, matrices treated, study scale; and
treatment levels achieved. Each data set is referenced and
quality-coded based on the analytical methods used, the
quality assurance/quality control efforts reported, and op-
erational information.
Version 4.0 of the data base is provided on a computer
diskette free of charge. The menu-driven program is com-
piled and docs not require specialized software. Computer
hardware and software requirements arc as follows:
• IBM-compatible personal computer and monitor
• 8-mcgabyte hard disk storage
• 640-K RAM memory
• DOS versions 2.0 to 3.3 or 5.0
• 12-pitch printer
57
-------
Requests for the data base must specify diskette format
(3'A HD, 5'A HD, or DD).
Alternative Treatment Technology
Information Center
Contact: Greg Ondich
Office of Environmental Engineering and
Technology Demonstration
U. S. Environmental Protection Agency
(202) 260-5747
System Operator
(301) 670-6294
System (online)
(301) 670-3808
The Alternative Treatment Technology Information Center
(ATTIC) is a comprehensive information retrieval system
containing up-to-date technical information on innovative
methods for treatment of hazardous wastes. Designed for
use by remediation personnel in the Federal, State, and
private sectors, ATTIC can be easily accessed free of charge
through an online system or the system operator.
The ATTIC system is a collection of hazardous waste data
bases that are accessed through a bulletin board. The
bulletin board includes features such as news items, special
interest conferences (e.g., the Bioremediation Special In-
terest Group), and a message board that allows direct com-
munications between users and with the ATTIC System
Operator (i.e.. Chat Mode). Users can access any of four
data bases: 1) the main ATTIC Data Base; 2) the RREL
Treatability Data Base; 3) the Technical Assistance Direc-
tory, which identifies experts on a given technology or
contaminant type; and 4) the Calendar of Events, which
contains information on upcoming relevant conferences,
seminars, and workshops.
The main ATTIC Data Base contains abstracts of Federal,
State, and private sector technical reports collected into a
keyword searchable format. Technologies are grouped into
five categories: 1) biological treatment, 2) chemical treat-
ment, 3) physical treatment, 4) solidification/stabilization,
and 5) thermal treatment.
In 1992, users of ATTIC will have online access to the
Inventory' of Treatability Study Vendors OTSV) data base.
The ITSV will aid in identifying vendors possessing quali-
fications to perform specific types of treatabilhy studies
and will supplement the existing two-volume, hard-copy
publication of the same name developed by RREL. The
online version of the ITSV will give users the ability to
screen the data base electronically and to review the infor-
mation by each of three main categories: technology,
media, and contaminant group.
Users can access ATTIC directly with a personal computer
and a modem. New users can register themselves and
assign their own password by calling the ATTIC System.
Communications software should be set according to the
following parameters prior to dialing:
• Baud Rate: 1200 or 2400
• Terminal Emulation: VT-100
• Data Bits: 8
• Stop Bits: 1
• Parity: None
• Duplex: Full
The ATTIC User's Guide is available by calling the System
Operator or leaving a message on the bulletin board.
Computerized On-Line Information
System
Contact: Robert Hillger
Risk Reduction Engineering Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
(908)321-6639
System Operator
(908)906-6851
System (online)
(908) 548-4636
The Computerized On-Line Information System (COLIS)
is operated by the Technical Information Exchange (TIX)
at the EPA's Risk Reduction Engineering Laboratory' in
Edison, New Jersey. A consolidation of several computer-
ized data bases, COLIS current!) contains the following
files:
• Underground Storage Tank (UST) Case History File-
provides technical assistance to Federal, State, and
local officials in responding to UST releases.
• Library Search System-contains catalog cards and ab-
stracts for technical documents in the TIX Library.
• SITE Applications Analysis Reports-provides perfor-
mance and cost information on technologies evaluated
under the Supcrfund Innovative Technology Evalua-
tion (SITE) Program.
• RREL Treatability Data Base
The system is menu-oriented, and online help is available.
Federal, State, and private sector personnel can access
COLIS free of charge by using a personal computer, a
modem, and a communications program. The COLIS User's
Guide is available by contacting the System Opcraior.
58
-------
Vendor Information System for
Innovative Treatment Technologies
Contact:
VISITT Hotline
(800) 245-4505
The Vendor Information System for Innovative Treatment
Technologies (VISITT) is an automated data base that
provides information on innovative treatment technologies.
The data base contains information submitted by develop-
ers and vendors of innovative treatment technology equip-
ment and services. Technologies to treat ground water in
situ, soils, sludges, and sediments are included.
Each vendor file in VISITT includes information on the
vendor, the technology, and the applicable contaminants/
matrices. Performance data, unit costs, equipment avail-
ability, permits obtained, instability study capabilities, and
references may also be available for some vendors/tech-
nologies.
The VISITT daui base is available on diskette and requires
a personal computer using a DOS operating system. Future
updates may be available on-line.
Superfund Technical Support Project
Contact: Marlene Suit
Technology Innovation Office
Office of Solid Waste and Emergency
Response
U.S. Environmental Protection Agency
(703) 308-8800
The Office of Solid Waste and Emergency Response
(OSWER), Regional Superfund Offices, and the Office of
Research and Development (ORD) established the Super-
fund Technical Support Project (TSP) in 1987 to provide
direct, technology-based assistance to the Regional Super-
fund programs through ORD laboratories. The project
consists of a network of Regional Technical Support Fo-
rums, five specialized Technical Support Centers (TSCs)
located in ORD laboratories, and one TSC located at the
Office of Emergency and Remedial Response (OERR) En-
vironmental Response Branch. The objectives of the TSP
are:
• To provide siatc-of-lhe-science technical assistance lo
Regional Remedial Project Managers (RPMs) and On-
Scenc Coordinators (OSCs).
• To -improve communications among the Regions and
the ORD laboratories.
• To ensure coordination and consistency in the applica-
tion of remedial technologies.
• To furnish high-technology demonstrations, workshops,
and information to RPMs and OSCs.
• To facilitate the evaluation and application of alterna-
tive investigatory and remedial techniques at Super-
fund sites.
The TSP is accessed by contacting one of the TSC Direc-
tors. Any Regional staff member involved in the Super-
fund program can contact the Centers directly or with the
assistance of a Forum member from their Region. Addi-
tional information on the TSP is available in:
Superfund Technical Support Project: Guide for RPMs/
OSCs. U.S. Environmental Protection Agency, Office
of Solid Waste and Emergency Response, Technology
Innovation Office, Washington, DC.
Engineering Technical Support Center
Contact: Ben Blaney or Joan Colson
Risk Reduction Engineering Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
(513)569-7406
One of the TSCs is the Engineering Technical Support
Center (ETSC) located at ORD's RREL Technical Support
Branch in Cincinnati, Ohio. The ETSC provides technical
assistance for reviewing and overseeing treatability work
plans and studies, feasibility studies, sampling plans, reme-
dial designs, remedial actions, and traditional and innova-
tive remediation technologies. Areas of expertise include
treatment of soils, sludges, and sediments; treatment of
aqueous and organic liquids; materials handling and decon-
tamination; and contaminant source control structures. The
following arc examples of the types of technical assistance
that can be obtained through the ETSC and the RREL
Technical Support Branch:
• Characterization of a site for treatment technology
identification
• Performance of remedy-screening trcatability studies
and support for treatability studies of innovative tech-
nologies at all tiers of testing
• Review of treatability study RFPs. work plans, and
final reports
• Oversight of trcatability studies performed by contrac-
tors and PRPs
• Assistance in design and startup of full-scale systems
59
-------
Treatability study assistance through the Superfund Tech-
nical Assistance Response Team (START) discussed in
Section 3.3 is also available through the ETSC contact
listed here.
Environmental Response Team
Technical Support Center
Contact: Joseph LaForNara
Environmental Response Branch
Office of Emergency and Remedial Response
U.S. Environmental Protection Agency
(908)321-6740
The Environmental Response Team (ERT) TSC is located
at the OERR Environmental Response Branch in Edison,
New Jersey. The ERT provides technical expertise for the
development and implementation of innovative treatment
technologies through its Alternative Technology Section.
The following are examples of the types of technical assis-
tance that can be obtained through the ERT:
• Consultation on water and air quality criteria, ecologi-
cal risk assessment, and treatability study test objectives
• Development and implementation of site-specific health
and safety programs
• Performance of in-house bench- and pilot-scale
treatability studies of chemical, physical, and biologi-
cal treatment technologies
• Sampling and analysis of air, water, and soil
• Provision of onsilc analytical support
• Oversight of trcauibilily study performance
• Interpretation and evaluation of treatability study data
60
-------
APPENDIX B
COST ELEMENTS ASSOCIATED WITH
TREATABILITY STUDIES
Section 2 of this guide describes three tiers of trcatability
testing: remedy screening, remedy-selection testing, and
remedial design/remedial action testing. This appendix
presents the cost elements associated with the various tiers
of trcatability studies. In some cases, unit costs arc pro-
vided; in other cases, project-specific examples arc pro-
vided that lend insight into the costs of various elements of
ircatability studies.
Many cost elements are applicable to all levels of ircatability
testing; however, some (e.g., the volume of residuals or
cost of analytical services) will increase from remedy screen-
ing 10 remedy-selection testing to RD/RA testing. Other
cost elements (e.g., site preparation and utilities) are only
applicable to RD/RA testing. Figure 11 shows the
applicability of the various cost elements to the different
treatability study tiers. The following is a discussion of
some of the key cost elements.
Vendor equipment rental is a key cost clement in the per-
formance of RD/RA testing. Most vendors have estab-
lished daily, weekly, and monthly rates for the use of their
treatment systems. These charges cover wear and tear on
the system, utilities, maintenance and repair, and system
preparation. In some cases, vendors include their opera-
tors, personal protective equipment, chemicals, and decon-
tamination in the rental charge. Treatment system rental
charges typically run about S5,000 to S20.000 per week.
Also, if the vendor sets up a strict timetable for testing, the
client may be billed S4000 to S5000 a day for each day the
waste is late in arriving at the facility.
Site preparation and logistics costs include costs associated
with planning and management, site design and develop-
ment, equipment and facilities, health and safety equip-
ment, soil excavation, feed homogcnization, and feed han-
dling. Costs associated with the majority of these activities
are normally incurred only with RD/RA testing of mobile
field-scale units; however, some of these cost elements
(e.g., feed homogenization and health and safety) arc also
incurred in bench- and pilot-scale remedy-selection testing.
Analytical costs apply to all tiers of irtalability studies and
have a significant impact on the total project costs. Several
factors affect the cost of the analytical program, including
the laboratory performing the analyses, the analytical target
list, the number of samples, the required turnaround time,
QA/QC, and reporting. Analytical costs vary significantly
from laboratory to laboratory; however, before prices arc
compared, the laboratories themselves should be properly
compared. The following arc typical of questions that
should be asked:
• What methods will be used for sample preparation and
analysis?
• What detection limits are needed?
• Does each laboratory fully understand the matrix that
will be received (e.g., tarry sludge, oily soil, slag) or
interference compounds that may be in the sample
(e.g., sulfidc)?
If all information indicates that the laboratories arc using
the same methods and equipment and understand the objec-
tives of the analytical program, the costs for analysis can be
compared.
One should also be aware that some analytes cost more to
analyze than others. Often, the project manager would like
to investigate some analytes for informational purposes
that may not be critical to the study. The decision as to
whether to analyze for these parameters could be simple if
the parameter-specific costs were known. For example,
TOC analysis of soil costs about S90/sample, whereas analy-
sis for total dioxins costs about S650/sample.
The number of samples, turnaround time, QA/QC, and
reporting also affect analytical costs. Laboratories often
give discounts on sample quantities greater than 5, greater
than 10, and greater than 20 when the samples arrive in the
laboratory at the same time. The laboratory' also applies
premium costs of 25. 50. 100, and 200 percent when ana-
61
-------
Cost Element
Labor
Testing
Equipment
Vendor Equipment
Rental
Field Instrumentation
and Monitors
Reagents
Site
Preparation
Utilities
Mobilization/
Demobilization
Permitting and
Regulatory
Health and
Safety
Sample
Transportation
Analytical
Services
Air Emission
Treatment
Effluent
Treatment
Decontamination
of Equipment
Residual
Transportation
Residual Treatment/
Disposal
T Testability Study Tier
Remedy
Screening
•
w
o
w
o
o
o
f~^
^•r
w
O
O
o
x-^
**
9
Remedy
Selection
•
•
O
o
o
o
w
r~N
r^
^
w
e
w
x-N
^
W
RO/RA
•
•
•
•
•
•
•
•
•
•
•
•
•
._. Not applicable
C j and/or no cost
> — ' incurred.
_^ May be applicable
^^ and/or intermediate
^^ cost incurred.
^^ Applicable
^A and/or high cost
^^ incurred.
Figure 11. General applicability of cost elements to various treatabllity study tiers.
62
-------
lyucal results arc requested faster than the normal turn-
around lime. If matrix spike and matrix spike duplicates
are required, the analytical cost will triple for those QA/QC
samples. Also, whether the laboratory provides a cover
letter with the attached data or a complete analytical report
will affect the analytical costs.
Residual transportation and disposal arc also important
elements (hat must be budgeted in the performance of all
treatability studies. Depending on the tcchnology(ies) in-
volved, a number of residuals will be generated. Partially
treated effluent, scrubber water, sludge, ash, spent filter
media, scale, and decontamination liquids/solids arc ex-
amples of residuals that musi be properly transported and
treated or disposed of in accordance with all local, Sme,
and Federal regulations. Unused feed and excess analytical
sample material also must be properly managed. Typi-
cally, a laboratory will add a small fee (e.g., $5 per sample)
to dispose of any unused sample material; however, the
unused raw material and residuals, which could amount to
a sizeable quantity of material, will cost significantly more
to remove. Transportation cost for a dedicated truck (as
opposed to a truck making a "milk run") is about S3.25 in
S3.75 per loaded mile. Costs for treatment of inorganic
wastewatcrs may range from S65 to S200 per 55-gallon
drum. Incineraiion of organic-contaminated wasiewatcrs
ranges from $200 to SI000 per 55-gallon drum, and
landfilling a 55-gallon drum of inorganic solids could cost
between S75 and S200. Disposal facilities also may have
some associated fees, surcharges, and other cosis for mini-
mum disposal, wasic approval, Slate and local taxes, and
stabilization.
63
-------
APPENDIX C
TECHNOLOGY-SPECIFIC
CHARACTERIZATION PARAMETERS
The tables in Appendix C contain waste feed characterization parameters specific to biological, physical/chemical,
immobilization, thermal, and in situ treatment technologies. Generally, these are the characterization parameters that must
be established before a treatability test is conducted on the corresponding technology. Additional parameters may be
required due to site-specific conditions.
Each table is divided by technology, waste matrix, parameter, and purpose of analysis. These tables arc designed to assist
the RPM in planning a treatabiluy study.
65
-------
Table 14. Waste Feed Characterization Parameters tor Biological Treatment
Treatment
Technology Matrix
Parameter
Purpose
General Soils/sludges Physical:
Moisture content
Temperature
Oxygen availability
Chemical:
PH
Total organic carbon
Redox potential
C:N:P ratio
Heavy metals
Chlorides/inorganic salts
Biological:
Soil biometry
Respirometry
Microbial identification
and enumeration
Microbial toxicity/growth
inhibition
Liquids Chemical:
PH
Dissolved oxygen
Chemical oxygen demand
Biological:
Biological oxygen
demand
Respirometry
Microbial identification
and enumeration
Microbial toxicity/growth
inhibition
To identify potential for microbial metabolism inhibition
and need for pretreatment.
To identify potential for microbial metabolism inhibition
and need for pretreatment.
To identify potential for microbial metabolism inhibition
and need for pretreatment.
To identify potential for microbial metabolism inhibition
and need for pretreatment.
To determine the need for possible organic carbon
supplementation to support acceptable levels of
biological activity.
To determine potential for stimulating and/or enriching
growth of indigenous aerobic, anoxic, suHate
reducing, and obligate anaerobic microbial
populations.
To determine mineral nutrient requirements.
To identify potential for microbial metabolism inhibition
and need for pretreatment.
To identify potential for microbial metabolism inhibition
and need for pretreatment.
To determine biodegradation potentials and to
quantify biodegradation rates.
To determine oxygen uptake and biodegradation
rates.
To determine the indigenous or adapted microbial
population densities in the inoculum.
To determine microbial activity.
To identify potential for microbial metabolism inhibition
and need for pretreatment.
To determine presence or absence of oxygen as a
potential indicator, respectively, of the absence or
presence of indigenous microbial activity.
To determine total oxygen demand, both organic and
inorganic, in the liquid matrix.
To determine the fraction of the chemical oxygen
demand that is aerobically degradable.
To determine oxygen uptake and biodegradation
rates.
To determine the indigenous or adapted microbial
population densities in the inoculum.
To determine microbial activity.
66
-------
Table 15. Waste Feed Characterization Parameters for Physical/Chemical Treatment
Treatment
Technology
Matrix
Parameter
Purpose and comments
General
Extraction
• Aqueous
- Solvent
- Critical fluid
- Air/steam
Chemical
dehalo -
genation
Soils/sludges Physical:
Type, size of debris
Dioxins/lurans,
radionuclides, asbestos
Soils/sludges Physical:
Panicle size distribution
Clay content
Moisture content
Chemical:
Organics
Metals (total)
Metals (leachable)
Contaminant
characteristics:
• Vapor pressure
• Solubility
• Henry's Law constant
• Partition coefficient
• Boiling point
• Specific gravity
Total organic carbon,
humic acid
Cation exchange capacity
Chemical oxygen demand
pH
Cyanides, sulfides,
fluorides
Biological:
Biological oxygen
demand
Soils/sludges Physical:
Moisture content
Particle-size distribution
Chemical:
Halogenated organics
Metals
pH/base absorption
capacity
Liquids Chemical:
Halogenated organics
To determine need for pretreatment.
To determine special waste-handling procedures.
To determine volume reduction potential.
pretreatment needs, solid/liquid separability.
To determine adsorption characteristics of soil.
To determine conductivity of air through soil.
To determine concentration of target or interfering
constituents, pretreatment needs, extraction medium.
To determine concentration of target or interfering
constituents, pretreatment needs, extraction mediurr,.
To determine mobility of target constituents,
posttreatment needs.
To aid in selection of extraction medium.
To determine presence of organic matter, adsorption
characteristics of soil.
To determine adsorption characteristics of soil.
To determine fouling potential.
To determine pretreatment needs, extraction medium.
To determine potential tor generating toxic fumes at
low pH.
To determine fouling potential.
To determine reagent formulation/loading.
To determine experimental apparatus.
To determine concentration of target constituents,
reagent requirements.
To determine concentration of other alkaline-reactive
constituents, reagent requirements. I
To determine reagent formulation/loading.
To determine concentration of target constituents,
reagent requirements.
67
-------
Table 15. (continued)
Treatment
Technology
Matrix
Parameter
Purpose and comments
Oxidation/ Soils/sludges Physical:
reduction Total suspended solids
Chemical:
Chemical oxygen demand
Metals (Cr*3, Hg. Pb, As)
Rocculation/ Liquids
sedimentation
Carbon
adsorption
Ion
exchange
Liquids
Gases
Liquids
pH
Physical:
Total suspended solids
Specific gravi;y of
suspended solids
Viscosity of liquid
Chemical:
pH
Oil and grease
Physical:
Total suspended solids
Chemical:
Organics
Oil and grease
Biological:
Microbial plate count
Physical:
Paniculates
Chemical:
Volatile organic
compounds, sulfur
compounds, mercury
Physical:
Total dissolved solids
Total suspended solids
Chemical:
Inorganic cations and
anions, phenols
Oil and grease
To determine the need for slurrying to aid mixing.
To determine the presence of oxidizable organic
matter, reagent requirements.
To determine the presence of constituents that could
be oxidized to more toxic or mobile forms.
To determine potential chemical interferences.
To determine reagent requirements.
To determine settling velocity of suspended solids.
To determine settling velocity of suspended solids.
To aid in selection of flocculating agent.
To determine need for emulsifying agents, oil/water
separation.
To determine need for pretreatment to prevent
clogging.
To determine concentration of target constituents,
carbon loading rate.
To determine need for pretreatment to prevent
clogging.
To determine potential for biodegradation of adsorbed
organics and/or problems due to clogging or odor
generation.
To determine need for pretreatment to prevent
clogging.
To determine concentration of target constituents,
carbon loading rate.
To determine concentration of target constituents,
carbon loading rate.
To determine need for pretreatment to prevent
clogging.
To determine concentration of target constituents.
To determine need for pretreatment to prevent
clogging.
68
-------
Table 15. (continued)
Treatment
Technology
Matrix
Parameter
Purpose and comments
Reverse Liquids Physical:
osmosis Total suspended solids
Chemical:
Metal ions, organics
PH
Residual chlorine
Biological:
Microbial plate count
Liquid/liquid Liquids Physical:
ex/raction Solubility, specific gravity
Chemical:
Contaminant
characteristics:
• Solubility
• Partition coefficient
• Boiling point
Oil/water Liquids Physical:
separation Viscosity
Specific gravity
Settleable solids
Temperature
Chemical:
Oil and grease
Organics
Air/steam Liquids Chemical:
stripping Hardness
Volatile organic
compounds
Contaminant
characteristics:
• Solubility
• Vapor pressure
• Henry's Law constant
• Boiling point
• Mass transfer coefficient
Chemical oxygen demand
Biological:
Biological oxygen
demand
Filtration Liquids Physical:
Total suspended solids
Total dissolved solids
To determine need for pretreatment to prevent
plugging of membrane.
To determine concentration of target constituents.
To evaluate chemical resistance of membrane.
To evaluate chemical resistance of membrane.
To determine potential for biological growth outside
membrane that would cause plugging.
To determine miscibility of solvent and liquid waste.
To aid in selection of solvent, separation of phases,
etc.
To determine separability of phases.
To determine separability of phases/emulsions.
To determine amount of residual solids.
To determine rise rate of oil globules.
To determine concentration of target constituents.
To determine need for posttreatment.
To determine potential for scale formation.
To determine concentration of target constituents.
To determine strippability of contaminants, size of
units, and need for posttreatment.
To determine stripping factor.
To determine packing height.
To determine fouling potential.
To determine fouling potential.
To determine need for pretreatment to prevent
clogging.
To determine need for posttreatment.
69
-------
Table 15. (continued)
Treatment
Technology Matrix
Dissolved air Liquids
dotation
Neutralization Liquids
Precipitation Liquids
Parameter
Physical:
Total suspended solids
Specific gravity
Chemical:
Oil and grease
Volatile organic
compounds
Chemical:
pH
Metals
Acidity/alkalinity
Cyanides, sulfides,
fluorides
Chemical:
Metals
Purpose and comments
To determine amount of residual sludge.
To determine separability of phases.
To determine concentration of target constituents.
To determine need for air emission controls,
posttreatment.
To determine reagent requirements
To determine need for posttreatment.
To determine reagent requirements.
To determine potential for generating toxic fumes at
low pH.
To determine concentration of target constituents,
Oxidation Liquids
(alkaline
chlorination)
Reduction Liquids
Hydrolysis Liquids
pH
Organics, cyanides
Chemical:
Cyanides
PH
Organics
Redox potential
Chemical:
Metals (Cr+6, Hg, Pb)
Chemical:
Organics
pH
reagent requirements.
To determine solubility of metal precipitates, reagent
requirements.
To determine concentration of interfering constituents,
reagent requirements.
To determine concentration of target constituents,
reagent requirements.
To determine suitable reaction conditions.
To determine potential for forming hazardous
compounds with excess chlorine (oxidizing agent).
To determine reaction success.
To determine concentration of target constituents,
reagent requirements.
To determine concentration of target constituents,
reagent requirements, posttreatment needs.
To determine reagent requirements.
70
-------
Table 16. Waste Feed Characterization Parameters for Immobilization
Treatment
Technology
Matrix
Parameter
Purpose and comments
Stabilization/ Soils/sludoes Physical:
solidification
Vitrification Soils/sludges
Description of materials
Particle-size analysis
Moisture content
Density testing
Weight ratio additives to
waste
Chemical:
Total organic content
pH
Alkalinity
Interfering compounds
Indicator compounds
Leach testing
•TCLP
• TCLP-water
Heat of hydration
Total waste analysis
Physical:
Depth of contamination
and water table
Soil permeability
Metal content of waste
material and placement of
metals within the waste
Combustible liquid/solid
content of waste
Rubble content of waste
Void volumes
Moisture content
Particle-size analysis
Chemical:
Leach testing
Total waste analysis
To determine waste handling methods (e.g., crusher,
shredder, removal equipment).
To determine surface area available tor binder contact
and leaching.
To determine amount of water to add/remove in S/S
mixing process.
To evaluate changes in density between untreated and
treated waste and to determine volume increase.
To determine effects of dilution due to volume increase.
To determine reagent requirements.
To evaluate changes in leaching as function of pH
between untreated and treated waste.
To evaluate changes in leaching as function of alkalinity
between untreated and treated waste.
To evaluate viability of S/S process. (Interfering
compounds are those that impede fixation reactions,
cause adverse chemical reactions, generate excessive
heat; interfering compounds vary with type of S/S).
To evaluate performance.
To evaluate performance based on regulatory test.
To evaluate performance under natural conditions.
To measure temperature changes during mixing.
To evaluate performance.
Technology is applied in unsaturated soils.
Dewatering of saturated soils may be possible.
Technology is applied in unsaturated soils.
Greater than 5 to 15% by weight or significant amounts
of metal near electrodes interfere with process.
Greater than 5 to 15% by weight interferes with process
(may ignite).
Greater than 10 to 20% by weight interferes with
process.
Large, individual voids (greater than 150 ft^) impede
process, may cause subsidence.
To determine power requirements.
To determine surface area available for binder contact
and leaching.
!
To evaluate performance.
To evaluate performance.
71
-------
Table 17. Waste Feed Characterization Parameters for Thermal Treatment
Treatment
Technology
General
Matrix
Soils/sludges
Physical:
Parameter
Purpose
and comments
Liquids
Moisture content
Ash content
Ash fusion temperature
Heat value
Chemical:
Volatile organics,
semivolatile organics
Principal organic
hazardous constituents
Total halogens
Total sulfur, total nitrogen
Phosphorus
PCBs and dioxins (if
suspected)
Metals
Physical:
Viscosity
Total solids content
Panicle-size distribution of
solid phases
Heat value
Chemical:
Volatile organics,
semivolatile organics
Principal organic
hazardous constituents
Total halogens
Total sulfur, total nitrogen
Phosphorus
PCBs, dioxins (if
suspected)
Affects heat value and material handling.
To determine the amount of ash that must be disposed
or treated further.
High temperature can cause slagging problems with
inorganic salts having low melting points.
To determine auxiliary fuel requirements and feed rates.
Allows determination of principal organic hazardous
constituents.
Allows determination of destruction and removal
efficiency.
To determine air pollution control devices for control ol
acid gases.
Emissions of SOx and NOx are regulated; to determine
air pollution devices.
Organic phosphorus compounds may contribute to
refractory attack and slagging problems.
99.9999% destruction and removal efficiency required
for PCBs; safety considerations; incineration is required
if greater than 500 ppm PCBs present.
Volatile metals' (Hg, Pb, Cd, Zn, As, Sn) may require
flue-gas treatment; other metals may concentrate in ash.
Trivalent chromium may be oxidized to hexavalent
chromium, which is more toxic. Presence of inorganic
alkali salts, especially potassium and sodium sulfate,
can cause slagging. Determine posttreatment needs.
Waste must be pumpable and atomizable.
Affects pumpability and heat transfer.
Affects pumpability and heat transfer.
Determine auxiliary fuel requirements and feed rates.
Allows determination of principal organic hazardous
constituents.
Allows determination of destruction and removal
efficiency.
To determine air pollution control devices for control of
acid gases. Chlorine could contribute to formation of
dioxins.
Emissions of SOx and NC\ are regulated; to determine
air pollution devices.
Organic phosphorus compounds may contribute to
refractory attack and slagging problems.
99.9999% destruction and removal efficiency required
for PCBs; safety considerations; incineration is required
if greater than 500 ppm PCBs present.
72
-------
Table 17. (continued)
Treatment
Technology
Matrix
Parameter
Purpose and r jmments
General
(cont.)
Liquids
Metals
Rotary kiln Soils sludges Physical:
Particle-size distribution
Debris Physical:
Amount, description of
materials
Presence of spherical or
cylindrical wastes
Fluidized-bed Soils/sludges Physical:
Ash fusion temperature
Ash content
Bulk density
Thermal Soils/sludges Physical:
descrption Moisture content
Particle-size distribution
Chemical:
PH
Volatile organic
contaminants
Volatile metals
Nonvolatile metals
Total chlorine
Total organic content
Liquids Physical:
Total solids content
Volatile metals (Hg, Pb, Co, Zn, As, Sn) may require
flue-gas treatment; othe. metals may concentrate in
ash. Trivalent chromium may be oxidized to
hexavalent chromium, which is more toxic. Presence
of inorganic alkali salts, especially potassium and
sodium sulfate, can cause slagging. Determine
posttreatment needs.
Fine particle size results in high paniculate trading
and slagging. Large particle size may present feeding
problems.
Oversized debris presents handling problems and kiln
refractory loss.
Spherical or cylindrical waste can roll through kiln
before combusting.
For materials with a melting point less than 1600CF,
particles melt and become sticky at high
temperatures, which causes defluidization of the bed.
Ash content;; greater than 65% can foul the bed.
As density increases, particle size must be decreased
for sufficient heat transfer.
Affects heating and materials handling.
Large particles result in poor performance. Fine silt or
clay generate fugitive dusts.
Very high or very low pH waste may corrode
equipment.
To determine concentration of target constituents.
posttreatment needs.
To determine concentration of target constituents,
posttreatment needs.
To determine posttreatment needs.
Presence of chlorine can affect volatilization of some
metals.
Limited to ~10 percent or less.
Minimum of 23-30 percent solids required.
73
-------
Table 18. Waste Feed Characterization Parameters for In Situ Treatment
Treatment
Technology
Matrix
Parameter
Purpose and comments
Vapor extraction
•Vacuum extraction
-Steam-enhanced
-Hot-air-enhanced
Solidification'/
stabilization
(undisturbed)
•Pozzolanic
-Polymerization
•Precipitation
Soil flushing
•Steam/hot water
•Surfactant
•Solvent
Vitrification
Electrokinetics
Microbial
degradation
•Aerobic
-Anaerobic
Adsorption (trench)
Soils/sludges Physical:
Vapor pressure of contaminants
Soil permeability, porosity,
particle-size distribution
Depth of contamination and
water table
Soils/sludges Physical:
Presence of subsurface barriers
(e.g., drums, large objects,
debris, geologic formations)
Depth to first confining layer
Soils/sludges Physical:
Presence of subsurface barriers
(e.g., drums, large objects,
debris, geologic formations)
Hydraulic conductivity
Moisture content (for vadose
zone)
Soil/water partition coefficient
Octanol/water partition coefficient
Cation exchange capacity
Alkalinity of soil
Chemical:
Major cations/anions present in
soil
Soils/sludges Physical:
Depth of contamination and
water table
Soils/sludges Physical:
Hydraulic conductivity
Depth to water table
Chemical:
Presence of soluble metal
contaminants
Soils/sludges Physical:
Permeability of soil
Chemical/biological:
Contaminant concentration and
toxicity
Soils/sludges Chemical/biological:
Contaminant concentration and
toxicity
Soils/sludges Physical:
Depth of contamination and
water table
Horizontal hydraulic flow rate
To estimate ease of volatilization.
To determine if the soil matrix will allow adequate
air and fluid movement.
To determine relative distance; technology
applicable in vadose zone.
To assess the feasibility of adequately delivering
and mixing the S/S agents.
To determine required depth of treatment.
To assess the feasibility of adequately delivering
the flushing solution.
To assess permeability of the soils.
To calculate pore volume to determine rate of
treatment.
To assess removal efficiency and to correlate
between field and theoretical calculations.
To assess removal efficiency and to correlate
between field and theoretical calculations.
To evaluate potential for contaminant flushing.
To estimate the likelihood of precipitation.
To estimate the likelihood of precipitation: to
estimate potential for plugging of pore volumes.
Technology is only applied in the unsaturated
zone.
Technology applicable in zones of low hydraulic
conductivity.
Technology applicable in saturated soils.
Technology applicable to soluble metals, hut not
organics and insoluble.
To determine ability to deliver nutrients or oxygen
to matrix and to allow movement of microbes.
To determine viability of microbial population in
the contaminated zone.
To determine viability of microbial population in
the contaminated zone.
Technology applicable in saturated zone.
To determine if ground water will come into
contact with adsorbent.
74
-------
United Stales
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penally tor Private Use
$300
Please make an necessary chances on the below label.
detach or copy, and return to the address In the upper
ten-hand comer.
If you do not wish to receive these reports CHECK HERE O
detach, or copy this cover, and return to trm address In the
upper left-hand comer.
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/540/R-92/071a
-------
Section 4
-------
GROUNDWATER CONTAINMENT
STUDENT PERFORMANCE OBJECTIVES:
At the conclusion of this section, participants will be able to:
Briefly describe the advantages and disadvantages of using groundwater
containment processes
Briefly describe the following passive control methods:
Slurry trench cutoff walls
Grout curtains
Sheet piling
Permeable treatment beds
Briefly describe the following dynamic control methods:
Groundwater pumping for plume control
Groundwater treatment and discharge systems.
5/93
-------
NOTES
THREE ALTERNATIVES AVAILABLE TO DEAL WITH
CONTAMINATED GROUNDWATER
• Physical Containment/Control
• Aquifer Rehabilitation
• Withdrawal, Treatment, and Use
PHYSICAL CONTAINMENT/CONTROL MEASURES
• Slurry Trench Cutoff Walls
• Grout Curtains
• Sheet Piling
• Permeable Treatment Beds
• Hydrodynamic Control
• Withdrawal, Treatment, and Recharge
SLURRY TRENCH CUTOFF WALLS
5/93
Groundwater Containment
page 1
-------
NOTES
Contaminant
Source
Slurry Trench
Cutoff Wall Production Well
Confining Bed
Cross Section of Slurry Trench Cutoff Wall
Keyed-in Slurry Wall
Hanging Slurry Wall
Leaking Fuel Tank
Groundwater Containment
page 2
5/93
-------
NOTES
Cut-Away Cross Section
of Upgradlent Placement With Drain
Cut-Away Cross Section of Downgradlent Placement
Cut-Away Cross-Section
of Circumferential Wall Placement
Water
Table
Low
Permeability
Zone \
Extraction
Well
Leachate
Level
5/93
Groundwater Containment
page 3
-------
NOTES
Slurry
Level'
Bentonite
Filter Cake
Impermeable Bedrock —
Slurry Trench During Construction
Typical Cap
2% Minimum Slop*
t
T
20 mil »ynth«tlo llntr
Topsoll
^ Flb*r
Sand
-^
Soil Liner
Ftbrlo
4 i
1 1.
^
.t
*
Waste
ADVANTAGES OF
SLURRY TRENCH CUTOFF WALLS
• Established Technique
• Single Construction
• Very Low Upkeep
• Long Service Life
• Relatively Effective
Qroundwater Containment
page 4
5/93
-------
NOTES
DISADVANTAGES OF
SLURRY TRENCH CUTOFF WALLS
• Limited to Unconsolidated Materials
• Relatively Expensive
• Limited Number of Construction
Contractors Available
GROUT CURTAINS
Contaminant
Source
Grout
Curtain Production Well
Confining Bed
Cross Section of Grout Curtain Installation
5/93
Groundwater Containment
page 5
-------
NOTES
Semicircular
Grout Tube8Grout
1,700ft.
Semicircular Grout Curtain Around a Contaminant Source
Grout Injection 5 ^
Tube
Radius of Influence
of Grout
Typical Two-Row Grid Pattern for Grout Curtain
ADVANTAGES OF GROUT CURTAINS
• Established Technique
• Very Low Upkeep
• Wide Range of Grouts Available
• Effective in Both Unconsolidated Materials
and Granular/Fractured Rock
Groundwater Containment
page 6
5/93
-------
NOTES
DISADVANTAGES OF GROUT CURTAINS
• Very Expensive
• Difficult to Evaluate Effectiveness
• Limited Number of Construction
Contractors Available
• Costs of Pre-grouting Testing are High
SHEET PILING
Contaminant
Source
Sheet Piling
Cutoff Wall Production Well
Confining Bed
Cross Section of Sheet Piling Installation
5/93
Groundwater Containment
page 7
-------
NOTES
Straight Web Type
Arch Web Type
Y-Fltfng
v
Deep Arch Web Type
T-Fitting
Z-Type
/
Steel Piling Shapes and Interlocks
ADVANTAGES OF SHEET PILING WALLS
• Established Technique
• Contractors Readily Available
• Relatively Inexpensive
• Low Maintenance Requirements
DISADVANTAGES OF SHEET PILING WALLS
• Only Effective in Unconsolidated Materials
• Difficult to Install in Rocky Materials
• Wall Initially not Waterproof
• Wall Susceptible to Corrosion
Groundwater Containment
page 8
5/93
-------
NOTES
PERMEABLE TREATMENT BEDS
Contaminant
Source
Permeable
Treatment Production
Bed Well
Confining Bed
Cross Section of Permeable Treatment Bed
MEDIA USED IN
PERMEABLE TREATMENT BEDS
• Crushed Limestone
• Activated Carbon
• Glauconitic Green Sands
5/93
Groundwater Containment
page 9
-------
NOTES
ADVANTAGES OF
CRUSHED LIMESTONE TREATMENT BED
• Can be used to Neutralize Acidic Ground
Water
• Can Remove Certain Heavy Metals
• Inexpensive
• Materials Readily Available
DISADVANTAGES OF
CRUSHED LIMESTONE TREATMENT BED
• Cementation of Limestone Bed May Occur,
Leading to Plugging of Flow
• Not Effective for Removal of Organic
Contaminants
• Maintenance Necessary to Retain Permeability
and Flow Through the Bed
• Channeling of Untreated Water Through the Bed
May Occur
ADVANTAGES OF
ACTIVATED CARBON TREATMENT BEDS
• Very Effective in Removal of Non-polar
Organic Compounds
• Readily Available Materials
• Easy to Install
Groundwater Containment
page 10
5/93
-------
NOTES
DISADVANTAGES OF
ACTIVATED CARBON TREATMENT BEDS
• Not Effective for Removal of Polar Organic Compounds
• Desorption of Adsorbed Compounds May Occur, Resulting in
Recontamination
• Removal/Disposal of Spent Carbon is Difficult and Hazardous
• Material is Very Expensive
• Plugging of the Bed May Occur, Backing Up Ground Water
and Result in Flooding
• Presence of Certain Chemicals May Decrease Effectiveness
of Adsorption
ADVANTAGES OF
GLAUCONITIC GREEN SAND TREATMENT BEDS
• Highly Effective in Removal of Many Heavy Metals
• Short Residence Time Required for Efficient
Treatment
• Relatively Little Material Required for Bed
• Material Abundant in Eastern U.S.
• Excellent Permeability
DISADVANTAGES OF
GLAUCONITIC GREEN SAND TREATMENT BEDS
• Saturation Characteristics Unknown
• Area of Application Limited By Availability of Material
• May Reduce pH Significantly
• Reduction in Permeability and Plugging of Bed May
Occur
• Removal Efficiencies of Metals at High
Concentrations Unknown
5/93
Groundwater Containment
page 11
-------
NOTES
HYDRODYNAMIC CONTROL
Confining Bed
Cross Section of Hydrodynamic Control System
Contaminant • contamination
Source • p,ume
Production
Well
0
Groundwater
Flow
Discharge Pipe
;
Plan View of Hydrodynamic Control System
Groundwater Containment
page 12
5/93
-------
NOTES
/ a
Withdrawal
Wells
Qroundwater Divide
Qroundwater Flowllnes
Hydrodynamlc Control/ Withdrawal-Recharge System
ADVANTAGES OF
HYDRODYNAMIC CONTROL
• High Design Flexibility
• Technology Readily Available
• Contractors Readily Available
• Construction Relatively Simple
• Relatively Inexpensive
• High Reliability
DISADVANTAGES OF
HYDRODYNAMIC CONTROL
• Continued Maintenance Necessary
• Requires Long-Term Commitment of Both Manpower
and Materials
• If Improperly Managed, Extracted Water May
Become Contaminated and Require Treatment
Before Injection
• Operation and Maintenance Costs Relatively High
• May Require Extensive Monitoring
5/53
Groundwater Containment
page 13
-------
NOTES
WITHDRAWAL, TREATMENT,
AND RECHARGE
Recharge
Well
Treatment _ .,
System E*"Sfl?n
W8II
Production Wall
Confining Bed
Withdrawal, Treatment, and Recharge System
Recharge Carbon
Wells Adsorption
Aeration
Basin
Extraction
Wells
Schematic of Withdrawal, Treatment, and Recharge System
Groundwater Containment
page 14
5/93
-------
NOTES
ADVANTAGES OF
WITHDRAWAL, TREATMENT, AND RECHARGE
• Treatment Processes Available for Most
Contaminants
• Only Method to Truly "Reclaim"
Contaminated Ground Water
• High Design Flexibility
• High Reliability
DISADVANTAGES OF
WITHDRAWAL, TREATMENT, AND RECHARGE
• Could Be Very Expensive Depending on Type and
Degree of Treatment
• Brings Large Volume of Uncontaminated Water to
the Surface Along with Contaminated Water
• Very Energy and Labor Intensive
• Possible Regulatory Problems with Discharge
• Does Not Work Well in Fine-Grained Material
COMPARATIVE INSTALLATION COSTS OF
PHYSICAL CONTAINMENT SYSTEMS
Method
Slurry Trench Cutofl Wall
Grout Curtain
Sheet Piling
Hydrodynamic Control
Dimensions
1,700 ft. long x 60 ft d«ep
1,700 ft. long x 60 ft deep
1,700 ft. long x 60 fl deep
1,000 ft long array
Range In Cost
(Thousands of Dollars)
500-840
800-1,400
650-960
200-350
5/93
Groundwater Containment
page 15
-------
NOTES
COMPARATIVE COSTS OF AQUIFER
REHABILITATION METHODS
Mtlhod
PKIKMM* Tmtnwit B»d«
Chtmlcal NeuffBlizetian
BiorKtanMJon
Withdrawal, TtMlmtnt. and Recharge
Dlmwitlont
I.OOOIongiSOIl d»^i
to acrn
10 tan
Rang* In Cost
(Thouundi ol DoOvi)
400-4,000
250-400
100-500
Highly Vulibl*
Groundwater Containment
page 16
5/93
-------
GROUNDWATER CONTAINMENT
SUBSURFACE BARRIERS
The term subsurface barriers refers to a variety of methods whereby low-permeability cutoff walls
or diversions are installed below ground to contain, capture, or redirect groundwater flow in the
vicinity of a site. The most commonly used subsurface barriers are slurry walls, particularly soil
bentonite slurry walls. Less common are cement-bentonite or concrete (diaphragm) slurry walls,
grouted barriers, and sheet piling cutoffs. Grouting may also be used to create horizontal barriers
for sealing the bottom of contaminating sites.
Slurry Walls
Slurry walls are the most common subsurface barriers because they are a relatively
inexpensive means of vastly reducing groundwater flow in unconsolidated earth materials.
The term slurry wall can be applied to a variety of barriers all having one thing in common:
they are all constructed in a vertical trench that is excavated under a slurry. This slurry,
usually a mixture of bentonite and water, acts essentially like a drilling fluid. It forms a
filter cake on the trench walls to prevent high fluid losses into the surrounding ground.
Types of slurry walls are differentiated by the materials used to backfill the slurry trench.
Most commonly, an engineered soil mixture is blended with the bentonite slurry and placed
in the trench to form a soil-bentonite slurry wall. In some cases, the trench is excavated
under a slurry of Portland cement, bentonite, and water, and this mixture is left in the trench
to harden into a cement-bentonite slurry wall. In the rare case where great strength is
required of a subsurface barrier, precast or cast-in-place concrete panels are constructed in
the trench to form a diaphragm wall. These types of slurry walls, including hybrids of the
three, are discussed on the next page.
Soil-Bentonite Slurry Walls
Soil-bentonite slurry walls are backfilled with soil materials mixed with a bentonite and water
slurry. Of the three major types of slurry walls, soil-bentonite walls offer the lowest
installation costs, the widest range of chemical compatibilities, and the lowest permeabilities.
At the same time, soil-bentonite walls have the highest compressibility (least strength),
require a large work area, and, because the slurry and backfill can flow, are applicable only
to sites that can be graded to nearly level (Spooner et.al., 1984a).
Applications and Limitations
One of the first steps in considering a soil-bentonite slurry wall for a given site is to
review the configuration options available and determine which best meets the goals
of the remedial action. In the vertical perspective, slurry walls may be "keyed-in"
or handing, as shown in FIGURE la. Keyed-in slurry walls are constructed in a
trench that has been excavated into a low-permeability confining layer such as a clay
5/93 17
-------
GROUNDWATER CONTAINMENT
deposit or competent bedrock. This layer will form the bottom of the contained site,
and a good key-in is essential to adequate containment. Hanging slurry walls,
however, are not tied to a confining layer but extend down several feet into the water
table to act as a barrier to floating contaminants (such as oils and fuels) or migrating
gases. The use of hanging slurry walls in waste site remediation is relatively rare,
and most installations are of the keyed-in variety.
In the horizontal perspective, slurry walls can be placed (relative to the direction of
groundwater flow) upgradient, downgradient, or completely surrounding the waste
site. The various horizontal placement options are shown in FIGURE la - e.
FIGURE la
KEYED-IN SLURRY WALL
5/93
18
-------
GROUNDWATER CONTAINMENT
FIGURE Ib
HANGING SLURRY WALL
SUWnv WALL
WATEP TABLE \ . H
ICJW PEBMEABUTY 2ONt ^-~=T-=-^=^
FIGURE Ic
CUT-AWAY CROSS-SECTION OF CIRCUMFERENTIAL WALL PLACEMENT
5/93
19
-------
GROUNDWATER CONTAINMENT
FIGURE Id
CUT-AWAY CROSS-SECTION OF DOWNGRADIENT PLACEMENT
FIGURE le
CUT-AWAY CROSS-SECTION OF UPGRADIENT PLACEMENT WITH DRAIN
5/93
20
-------
GROUNDWATER CONTAINMENT
Circumferential installations are by far the most common and offer several
advantages. This placement vastly reduces the amount of uncontaminated
groundwater entering the site from upgradient, thus reducing the volume of leachate
generated. Also, provided there are no compatibility problems between the site
wastes and the wall materials, the amount of leachate leaving the downgradient side
of the site will be greatly reduced. Moreover, when this configuration is used in
conjunction with an infiltration barrier and a leachate collection system (or other
means of reducing the hydraulic head on the interior of the wall), the hydraulic
gradient can be maintained in an inward direction, thus preventing leachate escape.
Upgradient placement is when a slurry wall is installed on the groundwater source
side of the wastes. Although no documented cases of upgradient installations were
found, this placement can be used to divert clean groundwater around a site in high
gradient situations. This method does not halt the generation of leachate but does
slow its generation by stagnating groundwater behind the wall.
Downgradient placement is when a slurry wall is installed on the side of a waste site
toward which groundwater is flowing. Although not common, this placement can be
employed as a hanging wall to contain and capture floating contaminants and
methane. Because there is direct leachate/wall contact in this configuration, extensive
compatibility testing is essential.
Another major concern in the application of soil-bentonite walls to site remediation
is the compatibility of the backfill mixture with site contaminants. Evidence indicates
that soil-bentonite backfills are not able to withstand attack by strong acids and bases,
strong salt solutions, and some organic chemicals (D'Appolonia, 1980b). The issue
of chemical incompatibility is discussed further under "Design Considerations."
Certain factors can limit the application of soil-bentonite to a particular site. Most
limitations can be overcome by increased engineering, but the associated cost increase
may make some other alternative, such as groundwater pumping, a more suitable
remedial measure.
Site topography can limit the use of a soil-bentonite wall. Because both the
excavation slurry and the backfill will flow under stress, the trench line must be
within a few degrees of level. In most cases, it is possible to grade the trench line
level prior to construction, but this is an added expense. If grading is not possible,
cement-bentonite slurry walls are an alternative for steeply sloping sites.
If a keyed-in slurry wall is considered, the depth to, and nature of, the confining
layer becomes a concern. The layer must be of sufficiently low permeability to
significantly retard downward migration at the design head levels. It must also have
sufficient thickness to allow for excavation of an adequate key-in (2 to 3 feet). The
depth to the confining layer will also determine the type of excavation equipment
used and the completed wall costs. Most slurry wall contractors have available
modified hydraulic backhoes capable of excavation to depths of 70 feet or more.
5/93 21
-------
GROUNDWATER CONTAINMENT
Below this level, more expensive specialty equipment such as clamshell grabs are
required, and costs increase dramatically.
Another limiting factor is the amount of work area required for soil-bentonite backfill
mixing. Ideally, there will be sufficient work area beside the trench to mix and place
the backfill. If such room is available, a central backfill mixing area can be
established, and the backfill can be hauled to the active trench portion.
Another limiting factor in the use of soil-bentonite slurry walls for pollution migration
control is the lack of long-term performance data. Soil-bentonite walls have been
used for decades for groundwater control in conjunction with large dam projects and
there is ample evidence of their success in this application. However, the ability of
these walls to withstand long-term permeation by many contaminants is unknown.
Most contaminant/backfill compatibility questions have been answered by laboratory
permeation tests and not by long-term studies. The issue of containment/backfill
compatibility is discussed further under "Design Considerations".
Design Considerations
Many factors must be considered in slurry wall design. The design must be based
on a detailed, design-phase investigation characterizing subsurface conditions and
materials, as well as disposition and nature of the waste. The issue of waste-wall
compatibility should be addressed early in the design by permeability testing of the
proposed backfill mixture with actual site leachate or groundwater. The design-phase
investigation results can then be used to decide on the optimum configuration and to
select any ancillary measures needed to enhance the performance of the wall. These
considerations are discussed further below. These and other design considerations
are covered in great detail in Slurry Trench Construction for Pollution Migration
Control (Spooner et. al., 1984a).
For most slurry walls installed to control contaminated groundwater, the most
important design consideration will be the permeability of the completed wall. The
soil-bentonite wall's permeability is dependent on the backfill mixture. The lowest
permeability is obtainable from backfills having 20- to 40-percent fine soil material
(passing a number 200 sieve) and preferably plastic fines (D'Appolonia, 1980b).
Although plastic fines are essential to achieving low permeability, there is evidence
to show that long-term wall performance in a contaminated environment will be more
certain if the backfill is composed of clays with a low activity index (defined as the
plasticity index divided by the percent by weight finer than two microns).
If a backfill mixture contains clays with a high activity index, the initial low
permeability of the wall could more easily be increased by physiochemical reactions
brought about by contaminants. This problem can be avoided by proper backfill
selection and testing.
5/93 22
-------
GROUNDWATER CONTAINMENT
A number of chemical compounds can have a detrimental effect on soil-bentonite
slurry walls. TABLE 1 shows how some chemicals can affect backfill permeability.
More recent information indicates that organic fluids can cause desiccation and
cracking in soil-bentonite backfill mixtures. This results in permeability increases of
several orders of magnitude. However, these same data indicate that these organics,
at or near their solubility limits in aqueous solution, caused no appreciable increases
in permeability (Evans, Fang, and Kugelman, 198S). Nonetheless, landfill and
lagoon leachates are often complex mixtures of chemicals and no pollution control
slurry wall should be installed without thorough compatibility testing.
TABLE 1
SOIL BENTONITE PERMEABILITY INCREASES
DUE TO LEACHING WITH VARIOUS POLLUTANTS
Pollutant
N =
M =
H =
* =
+ =
CA++ or Mg+ @ 1,000 ppm
Ca++ or Mg+ @ 10,000 ppm
NHjNOj @ 10,000 ppm
Acid(pH>l)
Strong acid (pHll)
HC1 (1%)
H2SO4(1%)
HC1 (5%)
NaOH(l%)
CaOH(l%)
NaOH (5%)
Benzene
Phenol solution
Sea water
Brine (SG - 1.2)
Acid mine drainage (FeS04, pH * 3)
Lignin (in Ca++ solution)
Organic residues from pesticide manufacture
Alcohol
Backfill*
N
M
M
N
M/H*
N/M
M/H*
N
N
M/H*
M
M/H*
N
N
N/M
M
M
N
N
N
M/H
No significant effect; permeability increases by about a factor of 2 or less at steady
state.
Moderate effect; permeability increases by factor of 2 to 5 at steady state.
Permeability increases by factor 5 to 10.
Significant dissolution likely.
Silty or clayey sand, 30 to 40% fines.
Source: D'Appolonia, 1980a; D'Appolonia and Ryan, 1979
5/93
23
-------
GROUNDWATER CONTAINMENT
After it is determined that a backfill mixture compatible with site wastes can be
designed, an assessment can be made on wall configuration. In most pollution
migration control applications, the wall will be keyed into a low permeability
confining layer beneath the site, and completely surround the site. Only in special
applications are hanging walls and partial walls used.
The design of a slurry wall for source control at a site must always consider how the
wall fits into the overall remedial response. Rarely, if ever, are slurry walls (or
other subsurface barriers) the only action taken in site remediation. At a minimum,
surface infiltration barriers (caps) are installed to prevent filling of the site interior
and overtopping of the wall. In some installations, extraction wells or drains are
used to maintain lower groundwater levels inside the wall than outside. This prevents
the site from filling and possibly floating the cover material off, and also keeps
groundwater flowing toward the interior, thus permeating the wall with groundwater
rather than leachate. Although such an installation would be more expensive and
would require a leachate treatment system, long-term performance of the wall would
be greatly enhanced.
Construction Considerations
Construction of a soil-bentonite slurry wall is relatively straightforward. The
equipment that is used is dependent on the depth and length of the wall. For walls
up to 80 feet deep, a backhoe or modified backhoe is used for excavation. Deeper
installations require the use of a mechanical or hydraulic clamshell or, in rare cases,
a dragline. Small volume wall installations may allow the use of batch slurry and
backfill mixing systems, while large jobs would require flash slurry mixers and a
large backfill mixing area. FIGURE 2 illustrates a typical slurry wall construction
site.
Regardless of the equipment used, the slurry is introduced just after the trench is
opened and before the water table is reached. The primary function of the slurry is
to act as hydraulic shoring to prevent trench collapse. There is also evidence to
indicate that the filter cake formed on the trench walls by the slurry contributes to the
low permeability of the completed wall.
5/93 24
-------
GROUNDWATER CONTAINMENT
FIGURE 2
TYPICAL SLURRY WALL CONSTRUCTION SITE
Source: Spooner et al., 1984a
5/93
25
-------
GROUNDWATER CONTAINMENT
After a sufficient length of wall is excavated to the design depth, backfilling can
begin. This is usually begun by using a clamshell to lower mixed backfill to the
trench bottom until the sloped backfill extends to the surface. Thereafter, the backfill
can be pushed into the trench with a bulldozer or poured from trucks using a trough,
and allowed to flow (not fall) down the sloped backfill. This procedure, with backfill
mixing alongside the trench, is shown in FIGURE 3.
Proper quality control during wall installation is essential. The most important
factors are checks of trench continuity and backfill mixing and placement.
BACKFILL MIXING AREA
TRENCH SPOILS
AREA OF ACTIVE
EXCAVATION
"•^EMPLACED.-'
" BACKFILL :••'.:•
UNEXCAVATED SOIL
FIGURES
CROSS-SECTION OF SLURRY TRENCH, SHOWING EXCAVATION
AND BACKFILLING OPERATIONS
Source: Spooner et al, 1984a
5/93
26
-------
GROUNDWATER CONTAINMENT
Backfill mixing and placement are carefully controlled during construction. The soil
that makes up the majority of the backfill is placed in the mixing area (either a
central area or alongside the trench) and slurry is added. The mixture is bladed and
tracked by a bulldozer until it is of relatively uniform consistency and of the proper
density. The backfill must be fluid enough to flow freely into the trench, but not so
fluid that it (1) fails to easily displace the slurry, (2) forms a slope so gentle that it
extends into the active excavation area, or (3) requires a great length of trench to be
kept open.
For circumferential installation, a portion of the backfill is reexcavated when the
circle is complete. The wall is then allowed to consolidate for up to several weeks.
Desiccation and consolidation cracks often form in the top few feet during this time.
These are often excavated and a compacted earth cap is placed along the wall to
prevent further desiccation or cracking. Where vehicular traffic must cross a wall,
traffic caps of aggregate and/or geotextiles are often constructed. Desiccation caps
and traffic caps are tied into the site surface cap.
Operation, Maintenance, and Monitoring
As passive measures, slurry walls require no operation and little maintenance.
Maintenance of the desiccation cap atop the wall is the only requirement that is
specific to the wall itself. Maintenance of ancillary measures such as caps and
leachate collection systems is important to the wall as part of the entire remedy.
Monitoring of slurry walls usually involves monitoring groundwater levels inside and
outside the wall to ensure that design head levels are not exceeded. Groundwater
quality monitoring can be used to determine the effectiveness of the entire remedial
effort.
Technology Selection/Evaluation
Soil-bentonite slurry walls are a relatively inexpensive and effective means of
controlling groundwater flow. They have been in use for decades to control seepage
through, under, and around large dams. In uncontaminated environments, they have
been shown to have long-term effectiveness and require little or no maintenance.
Although they are installed by specialty contractors, they are relatively easy to
construct and are effective in controlling groundwater immediately, provided head
differentials across the wall are within design tolerances. In contaminated
environments, however, their effectiveness over the longterm is very dependent on
the types of contaminants and their concentrations. Consequently, design of such
installations should always consider methods and measures of minimizing direct
contact of high-strength leachates with the wall. The integrity of any slurry wall
placed directly through wastes or kept in constant contact with high-strength leachates
must be questioned, and where questioned, verified by monitoring.
5/93 27
-------
GROUNDWATER CONTAINMENT
The major safety concerns for slurry wall installations arise from the excavation of
contaminated materials. These can cause disposal problems, increase air emissions
from the site, and greatly slow the pace of construction by requiring increased levels
of worker protection (i.e., supplied air). This is another reason that excavations
through deposited wastes should be avoided whenever possible.
Costs
Costs for slurry walls and other subsurface barriers are usually expressed in costs per
unit area of wall (dollars per square foot). Thus, total costs are determined by the
depth and the length. Width is determined by the excavation equipment being used.
TABLE 2 shows average costs for soil-bentonite and cement-bentonite slurry walls
and illustrates the effects of both the depth and ease of excavation on costs.
Operation and maintenance costs are negligible. These costs have been updated using
Engineering News Record cost indices for 1979 and 1984.
TABLE 2
RELATION OF SLURRY CUT-OFF WALL COSTS PER SQUARE FOOT
AS A FUNCTION OF MEDIUM AND DEPTH
Medium
Soft to Medium Soil N
Hard Soil N 40-200
Occasional Boulders
Soft to Medium Rock,
Boulder Strata
Hard Rock
Slurry Trench
Prices in 1984 Dollars -
Soil-Bentonite Backfill
(S/ft2)
Depth
<. 30
Feet
3-6
6-10
6-11
21-35
Depth
30-75
Feet
6-11
7-14
7-11
21-35
Depth
75-120
Feet
11-14
14-28
11-35
69-111
Unreinforced Slurry Wall
Prices in 1984 Dollars -
Cemeht-Bentonite Backfill
(S/ft2)
Depth
<60
Feet
21-28
35-42
28^2
42-55
Depth
60-150
Feet
28-42
42-55
42-55
85-132
Depth
> 150
Feet
42-104
55-132
55-118
132-292
Notes: N is standard penetration value in number of blows of the hammer per foot of penetration (ASTM
D1586-67).
* Normal Penetration Only: For standard reinforcement add $1 I/ft2.
For construction in urban environment add 25% to 50% of price.
Does not include cost of working in a contaminated environment.
5/93
28
-------
GROUNDWATER CONTAINMENT
Cement-Bentonite Slurry Walls
Cement-bentonite slurry walls share many characteristics with soil-bentonite slurry walls, but
are also different in some respects. The principal difference between the two is die backfill,
and this produces differences in applications, compatibilities, and costs. This discussion will
highlight the factors that distinguish cement-bentonite walls from soil-bentonite walls.
Cement-bentonite walls are generally excavated using a slurry of Portland cement, bentonite,
and water. This slurry is left in the trench and allowed to set up to form the completed
barrier. For extremely deep installations, a normal bentonite slurry is used for excavation,
then replaced by cement-bentonite.
Applications and Limitations
Cement-bentonite walls offer the same configuration options as soil-bentonite walls.
They are more versatile than soil-bentonite walls in two ways. First, because the
slurry sets up into a semirigid solid, this type of wall can accommodate variations in
topography by allowing one section to set while continuing the next section at a
higher or lower elevation. Second, because the excavation slurry is commonly the
backfill too, this type of wall is better suited to restricted areas where there is no
room to mix soil-bentonite backfill. Also, cement-bentonite is stronger than soil-
bentonite, so it is used where the wall must have less elasticity, such as adjacent to
buildings or roads.
Cement-bentonite slurry walls are limited in their use by their higher costs, somewhat
higher permeability, and their narrower range of chemical compatibilities. Cement-
bentonite walls average over 30-percent higher in cost than soil-bentonite walls. The
permeability of a cement-bentonite wall is normally around 1 x 10"6 cm/sec, while a
well-designed soil-bentonite wall is capable of achieving 1 x 10"8 cm/sec (Spooner et
al., 1984a). Cement-bentonite backfills are also more susceptible to chemical attack
than most soil-bentonite mixtures. Cement-bentonite is susceptible to attack by
sulfates, strong acids, and bases (pH <4 and ^7), and compatibility testing is
contained in Compatibility of Grouts with Hazardous Wastes (Spooner et al., 1984b).
Design and Construction Considerations
The design and construction of a cement-bentonite slurry wall is very similar to that
of a soil-bentonite wall. TABLE 3 shows typical compositions of cement-bentonite
slurries. Accelerators, retardants, and various other additives may be used but are
not common practice. FIGURE 4 illustrates the composition of cement-bentonite
slurries.
5/93 29
-------
GROUNDWATER CONTAINMENT
TABLE 3
TYPICAL COMPOSITIONS OF CEMENT-BENTONITE SLURRIES
Constituent
Percentage in Slurry
Bentonite
Water
Cement
without replacements
when blast furnace slag added, minimums
when fly ash added, minimums
Blast furnace slag, maximums, if used
Fly ash, maximums, if used
4-7
68-88
8-25
1-3
2-7
7-22
6-18
Non-Setting
Slurries
Semi
Fluids
Percent.
Cement
Source: Jefleris. 1981
Cut-Off
Slurries
Bleeding
Slurries
Percent
Bentonite
-Percent Water
FIGURE 4
COMPOSITION OF CEMENT-BENTONITE SLURRIES
5/93
30
-------
GROUNDWATER CONTAINMENT
Construction of a cement-bentonite wall is nearly identical to a soil-bentonite wall.
However, backfill mixing and the large area requirement are eliminated. Greater
care must be taken in slurry mixing because the mixture is more sensitive to small
changes in composition. Cement-bentonite walls are also usually finished with
desiccation caps to prevent harmful cracking.
Operation, Maintenance, and Monitoring
As with soil-bentonite walls, no maintenance is required. Maintenance and
monitoring are usually directed toward ancillary measures, and not toward the slurry
wall itself. However, it is important, as a part of the remedial effort, to monitor
water levels and groundwater quality to evaluate the success of the wall.
Technology Selection/Evaluation
Like soil-bentonite slurry walls, cement-bentonite walls can be an effective, relatively
inexpensive means of controlling groundwater flow. Most of the site constraints that
affect the selection of a soil-bentonite wall also apply to cement-bentonite walls.
Because cement-bentonite walls are more expensive, they are generally used where
(1) there is no room to mix and place soil-bentonite backfill, (2) increased strength
is required, or (3) extreme topography make it impractical to grade a site level.
As with any barrier installation, thorough compatibility testing is a must. Cement-
bentonite mixtures are somewhat more susceptible to chemical attack than most soil-
bentonites. They should not be placed directly through wastes or left unprotected
from attack by high-strength leachates.
Diaphragm Walls
Diaphragm walls are barriers composed of reinforced concrete panels (diaphragms), which
are emplaced by slurry trenching techniques. They may be cast-in-place or precast, and they
are capable of supporting great loads. This degree of strength is seldom, if ever, called for
at a hazardous waste site and their use is extremely rare. Because diaphragm walls are
constructed in slurry-filled trenches, it is possible to include them in cement-bentonite or soil-
bentonite walls for short sections, such as road or rail crossings, that require greater strength.
If the joints between the case panels are made correctly, diaphragm walls can be expected
to have permeabilities comparable to cement-bentonite walls. The same compatibility that
applies to cement-bentonite applies to diaphragm walls. Diaphragm walls are a specialty
item, and rarely used in pollution migration situations, so they are not discussed in detail
here.
Grouting
Grouting is a process whereby one of a variety of fluids is injected into a rock or soil mass
where it is set in place to reduce water flow and strengthen the formation. Because of costs,
grouted barriers are seldom used for containing groundwater flow in unconsolidated materials
5/93 31
-------
GROUNDWATER CONTAINMENT
around hazardous waste sites. Slurry walls are less costly and have lower permeability than
grouted barriers. Consequently, in waste site remediation, grouting is best suited for sealing
voids in rock. Even in cases where rock voids are transmitting large water volumes, a grout
can be formulated to set before it is washed out of the formation. The various types of
grouts that are available are discussed below, followed by discussions of the various ways
grouts may be employed. FIGURE 5 illustrates the range of grout applicability based on
grain size.
All Grouts
Acrylamides
Resins
Silicates
Clay-Bentonite
Cement
Emulsions
100
10
1.0
0.1
0.01
Cobbles
Gravel
Coarse
Fine
Sand
Coarse
Medium
Fine
Silt or Clay
FIGURES
APPLICABILITY OF DIFFERENT CLASSES OF GROUT
BASED ON SOIL GRAIN SIZE
Cement has probably been used longer than any other type of material for grouting
applications (Bowen, 1981). Cement grouts use hydraulic cement which sets, hardens, and
does not disintegrate in water (Kirk-Othmer, 1979). Because of their large particle size,
cement grouts are more suitable for rock, rather than soil, applications (Bowen, 1981).
However, the addition of clay or chemical polymers can improve the range of use. Cement
grouts have been used for both soil consolidation and water cut-off applications, but their use
is primarily restricted to more open soils. Typically, cement grouts cannot be used in fine-
grained soils with cracks less than 0.1 millimeter wide (Bowen, 1981).
5/93
32
-------
GROUNDWATER CONTAINMENT
Clays have been widely used as grouts, either alone or in formulations because they are
inexpensive (Guertin and McTigue, 1982). Only certain types of clay minerals possess the
physical and chemical characteristics favorable for use in grouting. These characteristics
include the ability to swell in the presence of water and to form a gel structure at low
solution concentrations. These properties are exhibited most markedly by the
montmorillonites. Other types of clay minerals, such as kaolinite and illite, can be used as
fillers in grout formulations, such as clay-cement mixtures (Greenwood and Raffle, 1963).
Bentonite grouts (high in calcium montmorillonite) can be used alone as void sealers in
coarse sands with a permeability of more than 102 ft/day (10'1 cm/sec). Bentonite-chemical
grouts can be used on medium to fine sands with a permeability between 102 ft/day (10"1
cm/sec) and 1 ft/day (10"3 cm/sec). Both of these grout types can also be used to seal small
rock fissures (Guertin and McTigue, 1982). Because of their low gel strengths, bentonite
grouts are not able to support structures and therefore can only be used as void sealers
(Tallard and Caron, 1977b).
Alkali silicates are the largest and most widely used chemical grouts. Sodium, potassium,
and lithium silicates are available, with sodium silicates being used more frequently.
Chemical grouts (i.e., silicates and organic polymers) constitute less than 5 percent by
volume of the grouts used in the United States, although they represent almost 50 percent of
the grouts used in Europe (Kirk-Othmer, 1979). In addition to their use as a grout, sodium
silicates may be used as additives to other grouts, such as Portland cement, to improve
strength and durability.
Silicates grouts are used for both soil consolidation and void sealing applications. These
grouts are suitable for subsurface applications in soils with a permeability of less than 10
ft/day (10'2 cm/sec). Silicate grouts are not suitable for open fissures or highly permeable
materials because of syneresis (water expulsion) unless they are preceded by cement grouting
(Karol, 1982a; Sommerer and Kitchens, 1980). Furthermore, tests conducted by the U.S.
Army Waterways Experiment Station found silicate grouts to be ineffective in waterproofing
fine-grained soils (Hurley and Thornburn, 1971).
Organic polymer grouts represent only a small fraction of the grouts in use. These grouts
consist of organic materials (monomers) that polymerize and crosslink to form an insoluble
gel. The organic polymer grouts include:
• Acrylamide grouts
• Phenolic grouts
• Urethane grouts
• Urea-formaldehyde grouts
• Epoxy grouts
5/93 33
-------
GROUNDWATER CONTAINMENT
• Polyester grouts.
Acrylamide grouts have been in use for about 30 years and were the first of the organic
chemical polymer grouts to be developed. Acrylamide grouts have the largest use among the
existing organic polymer grouts and are the second most widely used chemical grouts (after
silicates) (Karol, 1982a). They may be used alone or in combination with other grouts such
as silicates, bitumens, clay, or cement (Tallard and Caron, 1977a).
Acrylic and polyacrylamide grouts are typically used in ground surface treatment, ground
treatment for oil well drilling, and subsurface applications (e.g., waterproof concrete
structures). Aery late grouts are more commonly used for ground surface treatment than for
soil injection where acrylamide grouts are more frequently used.
Acrylamide applications include structural support and seepage control for mines, soil
consolidation for foundations of structures and dams, and water control and soil consolidation
for tunnels, wells, and mines (Tallard and Caron, 1977a). Specific applications include grout
curtains, loose sand stabilization, artesian flow shut-off, and water seepage control in jointed
and fissured rock (Office of the Chief of Engineers, 1973). Based on AM-9 applications,
acrylamide grouts may be used in a variety of soil materials such as fine gravel; course,
medium, or fine sand; and some clays (Herndon and Lenahan, 1976).
Urethane grouts are the second most commonly used type of organic polymer grout (Jacques,
1981). Urethane grouts were developed in Germany for consolidation applications and are
now used in Europe, South Africa, Australia, and Japan (Sommerer and Kitchens, 1980).
These grouts are used for water and soil applications and can penetrate finely fissured
material.
The use of phenolic resin in underground and foundation construction began in the 1960s
(Kirk-Othmer, 1979; Tallard and Caron, 1977a). These grouts may be used in fine soils and
sands for a variety of water control and ground treatment applications.
However, phenolic grouts are not widely used alone but are typically used in conjunction
with other grouts (Tallard and Caron, 1977a).
Urea-formaldehyde resins are frequently referred to as aminoplasts. The idea for the use of
these resins as grouts came from their use as glue in the oil industry (Tallard and Caron,
1977a). Although urea-formaldehyde grouts have been available since the 1960s, they have
found limited use (Karol, 1982b; Sommerer and Kitchens, 1980). These grouts can setup
only in an acid environment; therefore, they cannot be used in basic formations.
Epoxy grouts and other glue-like grouts have been in use since 1960. These grouts have had
limited use in soil grouting primarily because of their high cost (Tallard and Caron, 1977a).
Most of the applications reported in the literature involve the use of epoxy resins in mortars
and for sealing cracks. Epoxy resins can adhere to and seal submerged concrete, steel, or
wood surfaces, and are useful in water applications (Engineering News-Record, 1965). They
5/93 34
-------
GROUNDWATER CONTAINMENT
have been used for grouting cracked concrete for structural repairs and grouting fractured
rock to improve its strength (Office of the Chief of Engineers, 1973).
Polyester grouts have been in use since the 1960s. They have been used in a variety of
construction applications, principally to treat cracks in buildings and structures (Tallard and
Caron, 1977a). These grouts have also been used in mines as well as to stabilize and
strengthen porous and fissured rock (Tallard and Caron, 1977a; Office of the Chief of
Engineers, 1973). Polyester grouts have been used infrequently to treat sand (Tallard and
Caron, 1977a).
The compatibility of these grouts with hazardous wastes and leachates has not been studied
in great detail, and only general incompatibilities are known. One recent study indicates the
response of several grouts to various organic chemicals is unpredictable and often drastic
(Bodocsi, 1985). Therefore, where grouting is considered a remedial option, thorough
compatibility tests must be performed.
The component parts of some grouts, such as acrilimides and urea-formaldehydes, are toxic.
Unless the setting reactions are carefully controlled, there is a likelihood that unreacted, toxic
compounds will be released into the ground. A thorough characterization of the waste and
grout chemistry, as well as the site geochemistry, is required.
Rock Grouting
One of the greatest potential uses for grouting in hazardous waste site remediation is for
sealing fractures, fissures, solution cavities, or other voids in rock. Nonetheless, rock
grouting at waste sites is uncommon and no actual applications were found in the literature.
Applications and Limitations
Rock grouting may be applied to a waste site to control the flow of groundwater
entering a site. In theory, grouting could also control leachate flow in rock, yet in
many cases, contaminants interfere with grout setting reactions and/or reduce grout
durability. In many cases, the waste/grout interaction and compatibility cannot be
predicted and extensive testing is required. These issues are discussed in detail in
Compatibility of Grouts with Hazardous Wastes (Spooner et al., 1984b).
Design and Construction Considerations
As with other types of barrier construction, the ultimate success of a grouting project
depends on thorough site characterization. The ability to seal water-bearing voids or
zones is dependent on being able to locate them.
In many remedial grouting operations, only a small portion of the rock mass will
transport water and must be sealed. Consequently, the exploratory investigation must
be very thorough. Detailed geologic mapping of the site, aided by remote sensing
techniques and extensive rock coring, is required. Even with extensive investigation,
5/93 35
-------
GROUNDWATER CONTAINMENT
the complexity of groundwater flow in fractured and fissured bedrock can make a
grouting project impossible to plan completely in advance.
Based on background and exploratory data, the location for a pattern of primary
injection holes is chosen, and injection at one or more zones is identified. The first
few primary holes are then drilled and pressure washed with water and air (Millet and
Engelhardt, 1982). This step removes drill cuttings and other debris from the hole
to allow better grout penetration. Each hole is then pressure tested, often using a
nonsetting fluid of the same viscosity as the grout to be used. These tests are used
to determine the initial grout mixture and are often conducted using the grout plant
and other equipment to be used for the actual grouting.
Each zone within each primary hole is then injected with the grout mixture until a
predetermined amount is pumped (grout take) or a predetermined flow rate at
maximum allowable pressure is reached. Maximum allowable pressure is typically
around 1 pound per square inch (psi) per foot of overburden (Millet and Engelhardt,
1982).
Data from the drilling and injection of the first primary holes is analyzed and, if
necessary, the grout mixture or injection pressure is modified before completing the
remaining primary holes. After the primary hole grouting is completed, the program
is analyzed again, necessary changes are made, and a pattern of more closely spaced
secondary holes are drilled and injected.
The analysis and evaluation of the completed grouting becomes, in essence, another
pressure test. Close quality control during drilling and grouting identifies areas that
require tertiary hole grouting to complete sealing. Such areas are identified by faster
than expected drilling rates and higher than expected grout takes (Millet and
Engelhardt, 1982).
For a successful grouting program, each hole series (e.g., primary or secondary) will
have lower grout takes than the previous one. Many projects will require that
tertiary, or proof holes be drilled and injected. A very low grout take on proof holes
indicates that most voids are grout filled and the grouting program was successful.
Operation, Maintenance, and Monitoring
As with other subsurface barriers, operation and maintenance requirements are
negligible. Monitoring programs, consisting of hydrologic measurements and water
quality assessments, are used to evaluate the effectiveness of the completed barrier.
Technology Selection/Evaluation
Rock grouting is very much a specialty operation. It is performed by a limited
number of contractors, and each such program is highly sitespecific. Because this
technique has rarely, if ever, been applied to controlling highly contaminated
5/93 36
-------
GROUNDWATER CONTAINMENT
groundwater, an assessment of performance and reliability is not possible. Each
instance where rock grouting is feasible for site remediation must be evaluated on a
case-by-case basis.
Costs
Each rock grouting job is highly site specific, and valid costs vary widely. Example
costs for some common grouts are shown in TABLE 4. These costs have been
updated using the Engineering News-Record cost indices for 1979 and 1985.
Grout costs for a completed job show much less variation. This is because the
cheaper, paniculate grouts are used to seal large voids, thus using more grout,
whereas the more expensive chemical grouts are commonly used to seal small voids.
TABLE 4
APPROXIMATE COSTS OF COMMON GROUTS
Grout Type
Portland Cement
Bentonite
Silicate - 20%
30%
40%
Epoxy
Acrylamide
Urea Formaldehyde
Approximate Cost ($/ga!lon)
of Solution (1985)
1.33
1.76
1.76
2.95
3.86
42.15
9.34
8.00
As an example of costs for rock grouting, assume that a 1,000-foot-long barrier, that
is 6 feet thick and 30 feet deep is to be placed in rock with 20-percent void space.
A double row of injection holes, 6 feet on center, will be used (333 holes), and 40-
percent sodium silicate grout will be injected. Approximate costs are given in
TABLE 5.
5/93
37
-------
GROUNDWATER CONTAINMENT
TABLE 5
APPROXIMATE COSTS ($ 1985) FOR GROUND BARRIER IN ROCK
Unit Operation
Injection Hole drilling
Grout Pipe
Grout injection
Grout - 40%
Approximate Unit Cost
$14. 16 per foot -9990 feet
$8.49 per foot - 99990 feet
$5.66 per cubic yard - 1333
cubic yards
$3.86 per gallon - sodium
silicate - 35,991 gallons
Total Cost *
Approximate Cost
$141,440
$84,869
$7,549
$139,039
$391,097
* Does not include site investigation and characterization
Grout Curtains
Grout curtains are subsurface barriers created in unconsolidated materials by pressure
injection. The various methods of forming a grout curtain are described below under design
and construction considerations.
Grout barriers can be many times more costly than slurry walls and are generally incapable
of attaining truly low permeabilities in unconsolidated materials. A recent field test study
of two chemical grouts revealed significant problems in forming a continuous grout barrier
due to noncoalescence of grout pads in adjacent holes and grout shrinkage. This study
concludes that conventional injection grouting is incapable of forming a reliable barrier in
medium sands (May et al., 1985). Therefore, they are rarely used when groundwater control
in unconsolidated materials is desired.
Applications and Limitations
Grout curtains, like other barriers, can be applied to a site in various configurations.
Circumferential placement offers the most complete containment but requires that
grouting take place in contaminated groundwater downgradient of the source. As
discussed under rock grouting, this could easily cause problems with grout set and
durability. As with other techniques, this requires extensive compatibility testing
during the feasibility study. Another limitation of curtain grouting is the problem of
gaps left in the curtain due to nonpenetration of the grout. Only a few small gaps in
an otherwise low-permeability curtain can increase its overall permeability
significantly.
5/93
38
-------
GROUNDWATER CONTAINMENT
Design and Construction Considerations
The design of a grout curtain must be based on a thorough site characterization.
Analysis of site characterization data, including boring logs, pump or injection test
results, and other data, is used to determine whether a site is groutable. These data
are also used to determine which grout is most suitable based on viscosity,
compatibility, and ultimate permeability. This is a very involved process and should
be conducted by an experienced engineer.
Construction of a grout barrier is accomplished by pressure injecting the grouting
material through a pipe into the strata to be waterproofed. The injection points are
usually arranged in a triple line of primary and secondary grout holes. A
predetermined quantity of grout is pumped into the primary holes. After the grout
in the primary holes has had time to gel, the secondary holes are injected. The
secondary grout holes are intended to fill in any gaps left by the primary grout
injection (Hayward Baker, 1980). The primary holes are typically spaced at 20- to
40-foot intervals (Guertin and McTigue, 1982). FIGURE 6 illustrates a grout
curtain.
Semicircular
Grout Curtain
Secondary
Grout Tubes
Primary
Grout Tubes
FIGURE 6
SEMICIRCULAR GROUT CURTAIN AROUND WASTE SITE
Source: Spooner et. al., 1984b
5/93
39
-------
GROUNDWATER CONTAINMENT
Several basic techniques are used to form the grout wall. These include (Hayward
Baker, 1980; Guertin and McTigue, 1982):
• Stage-up method
• Stage-down method
• Grout port method
• Vibrating beam method.
Stage-up method: The borehole is drilled to the full depth of the wall prior to grout
injection. The drill is withdrawn one "state," leaving several feet of borehole
exposed. Grout is then injected into this length of open borehole until the desired
volume has been injected. When injection is complete, the drill is withdrawn further
and the next stage is injected (Hayward Baker, 1980).
Stage-down method: Grouting differs from stage-up grouting in that the injections are
made from the top down. Thus, the borehole is drilled through the first zone that is
to be grouted, the drill is withdrawn, and the grout injected. Upon completion of the
injection, the borehole is redrilled through the grouted layer into the next zone to be
grouted and the process is repeated (Guertin and McTigue, 1982).
Grout port method: This method uses a slotted injection pipe that has been sealed
into the borehole with a brittle Portland cement and clay mortar jacket. Rubber
sleeves cover the outside of each slit (or port), permitting grout to flow only out of
the pipe.
The injection process begins by isolating the grout port in the zone to be injected
using a double packer. A brief pulse of high-pressure water is injected into the port
to rupture the mortar jacket. Grout is pumped between the double packers and then
passes through the ports in the pipe, under the rubber sleeve, and out through the
cracked mortar jacket into the soil (Guertin and McTigue, 1982).
Vibrating beam method: This method places, instead of injects, grout to generate a
wall. In this method, an I-beam is vibrated into the soil to the desired depth and then
raised at a controlled rate. As the beam is raised, grout is pumped through a set of
nozzles mounted in the beam's base to fill the newly formed cavity.
When the cavity is completely filled, the beam is moved less than one beam width
along the wall, leaving a suitable overlap to ensure continuity (Harr, Diamond, and
Schmednect, undated). This method is illustrated in FIGURE 7.
5/93 40
-------
GROUNDWATER CONTAINMENT
Vibrating
Hammer
Beam
Grouted
Sections
\
Top View
• n
H
u
Typically
FIGURE?
VIBRATING BEAM GROUT INJECTION
5/93
41
-------
GROUNDWATER CONTAINMENT
Operation, Maintenance, and Monitoring
Grout curtains, which require no operation and little or no maintenance, may require
more monitoring than other barriers. Even a very small gap left in the barrier can
enlarge quite rapidly by piping or tunneling if there is a sufficient hydraulic gradient
across the wall.
Technology Selection/Evaluation
Grout curtains are a specialty technology seldom applied to hazardous waste sites (an
exception is the vibrating beam wall with bitumen grout, which has seen some
application in recent years). As such, no detailed assessment of the performance or
reliability of this technology is possible.
Costs
As with rock grouting, each curtain grouting job is highly site specific. Each site
requires differing degrees of investigation and characterization. The grout injection
program must be tailored to its characteristics. The costs given for rock grouting can
serve as an example of curtain grouting. Example grout costs are shown in TABLE
4.
Sheet Piling
In addition to slurry wall and grouted cut-offs, sheet piling can be used to form a
groundwater barrier. Sheet piles can be made of wood, precast concrete, or steel. Wood
is an ineffective water barrier. Therefore, concrete is used primarily where great strength
is required. Steel is the most effective in terms of groundwater cut-off and cost, so steel
sheet pilings are discussed here.
Applications and Limitations
Steel sheet piling can be employed as a groundwater barrier much like the others
discussed in this chapter. Because of costs and unpredictable wall integrity, however,
it is seldom used except for temporary dewatering for other construction, or as
erosion protection where some other barrier, such as a slurry wall, intersects flowing
surface water.
One of the largest drawbacks of sheet piling, or any other barrier technology
requiring pile driving, is the problem caused by rocky soils. Damage to, or
deflection of, the piles may render the wall ineffective as a groundwater barrier.
Design and Construction Considerations
The primary design parameters for any barrier are permeability and dimensions.
Dimensional requirements are based on site characteristics and are straightforward.
5/93 42
-------
GROUNDWATER CONTAINMENT
Depth limitations are governed by the soil material at the site. Design factors for
ultimate permeability of the cut-off are more complicated and must assume some
factor to account for leakage through the interlocking joints. Typical shapes for steel
sheet piling are shown in FIGURE 8.
Straight Web Type
Arch Web Type
Deep Arch
Web Type
Z-Type
Y-Frctina
T-Fming
FIGURES
SOME STEEL PILING SHAPES AND INTERLOCKS
Source: Ueguhardt et. al., 1962
5/93
43
-------
GROUNDWATER CONTAINMENT
To construct a sheet piling cut-off, the pilings are assembled at their edge interlocks
before they are driven into the ground. This arrangement ensures that earth materials
and added pressures will not prevent a good lock between piles. The piles are then
driven a few feet at a time over the entire length of the wall. This process is repeated
until the piles are all driven to the desired depth.
The sheet piling is forced into place by a drop hammer or a vibratory hammer.
Heavy equipment is desirable for fast driving and to prevent damage to the piles.
Lightweight equipment can distort the top edge of the pile and slow the driving
(ARMCO, Inc., Baltimore, MD, personal communication, 1980). Often, a cap block
or driving head is placed on the top edge to prevent the driving equipment from
damaging the piles.
When first placed in the ground, sheet piling cut-offs are quite permeable. The edge
interlocks, which are necessarily loose to facilitate placement, allow water easy
passage. With time, however, fine soil particles are washed into the seams and water
cut-off is affected. The time required for this sealing to take place depends on the
rate of groundwater flow and the texture of the soil involved. In very coarse, sandy
soils, the wall may never seal. In such cases, it is possible to grout the piling seams,
but this is a costly operation.
Operation, Maintenance, and Monitoring
Steel sheet piling cut-offs require little maintenance. In corrosive soils, galvanized
or polymer-coated piles or cathodic protection can prolong the service life of cut-off.
However, these measures must be incorporated prior to construction. Monitoring of
sheet piling cut-offs parallels that for other barriers and involves monitoring head
levels and groundwater quality on either side of the barrier to determine whether it
is functioning as designed.
Technology Selection/Evaluation
The performance life of a sheet piling wall can be between 7 and 40 years, depending
on the condition of the soil in which the wall is installed. Sheet piling walls have
been installed in various types of soils ranging from well-drained sand to impervious
clay, with soil resistivities ranging from 300 ohm/cm to 50,000 ohm/cm, and with
soil pH ranging from 2.3 to 8.6. Inspections of these installed walls did not reveal
significant deterioration of the structure due to soil corrosion (US EPA, 1978).
Additional protection of the sheet piling wall against corrosion can be achieved by
using hot-dip galvanized, or polymer-coated, sheets. Cathodic protection has also
been suggested for submerged piling (US EPA, 1978).
Steel sheet piles should not be used in very rocky soils. Even if enough force can be
exerted to push the piles around or through cobbles and boulders, the damage to the
piles will render the wall ineffective.
5/93 44
-------
GROUNDWATER CONTAINMENT
Costs
The cost of installed steel sheet piling will vary with depth, total length, type of pile
(coated or uncoated), and relative ease of installation. Average costs range from
approximately $6.50 per square foot up to approximately $16.00 per square foot
(Godfrey, 1984a; McMahon, 1984a).
Bottom Sealing
Bottom sealing refers to techniques used to place a horizontal barrier beneath an existing site
to act as a floor and prevent downward migration of contaminants. Most of these techniques
involve variations of grouting or other construction support techniques. No documentation
applicable to hazardous waste sites was found.
Grouting
Emplacement of a bottom seal by grouting involves drilling through the site, or directional
drilling from the site perimeter, and injecting grout to form a horizontal or curved barrier.
One such technique, jet grouting, involves drilling a pattern of holes across the site to the
intended barrier depth.
A special jet nozzle is lowered and a high pressure stream of air and water erodes the soil.
By turning the nozzle through a complete rotation, a flat, circular cavity is formed. The
cavity is then grouted with intersecting grouted masses forming the barrier. The directional
drilling method is very similar to curtain grouting except that it is performed in slanted rather
than vertical, boreholes.
These techniques are currently under development. Therefore, no detailed analysis of
applications, limitations, design, or construction considerations is possible.
PERMEABLE TREATMENT BEDS
Bed Types
Permeable treatment beds are essentially excavated trenches placed perpendicular to
groundwater flow and filled with an appropriate material to treat the plume as it flows
through the material (FIGURE 9). Some of the materials that may be used in the treatment
bed are limestone, crushed shell, activated carbon, glauconitic green sands, and synthetic ion-
exchange resins.
5/93 45
-------
GROUNDWATER CONTAINMENT
Permeable Treatment Bed
Groundwater flow
FIGURE 9
INSTALLATION OF A PERMEABLE TREATMENT BED
5/93
46
-------
GROUNDWATER CONTAINMENT
Permeable treatment beds have the potential to reduce the quantities of contaminants present
in leachate plumes. The system is applicable to relatively shallow groundwater tables
containing a plume. To date, permeable treatment beds have not been applied at hazardous
wastes sites. However, bench- and pilot-scale testing has provided preliminary quantification
of treatment bed effectiveness.
Use of a permeable treatment bed poses several problems. These include saturation of bed
material, plugging of bed with precipitates, and short life of treatment materials. Therefore,
permeable treatment should be considered a temporary, not a permanent, remedial action.
A limestone or crushed shell bed can be used to neutralize acidic groundwater and retain
certain metals such as cadmium, iron, and chromium. The effectiveness of limestone as a
barrier depends primarily on the pH and volume of the solution passing through the
limestone. The nature of the metal is also an important factor. A laboratory study
demonstrated that limestone was more effective at retaining chromium III than chromium VI
and other metals (Artiola and Fuller, 1979).
Fuller and other researchers (US EPA, 1978) have discussed the use of crushed limestone
as an effective, low-cost landfill liner to lessen the migration of certain heavy metals from
solid waste leachates. The authors state that dolomitic limestone (containing significant
amounts of magnesium carbonate) is less effective in removing ions than purer limestone
containing little magnesium carbonate. Therefore, use of limestone with high calcium content
is recommended in design of a limestone treatment bed. This design will remove heavy
metals and neutralize contaminated groundwater.
In regard to designing vertical permeable treatment beds, the selection of the particle size of
the limestone that is used should be based on the type of soil in which groundwater flows and
the level of contamination. The type of soil is important because it controls groundwater
flow rates. In general, a mixture of gravel-size and sand-size limestone should be used to
minimize settling through dissolution. Where excessive channeling through the bed by rapid
groundwater movement is expected or where improved contact time between the
contaminated groundwater and the treatment bed is required, a higher percentage of sand-size
particles is more appropriate.
One variation in the use of limestone permeable treatment beds to neutralize plumes is to
apply layers of limestone or crushed shell over a waste site. This indefinitely stabilizes the
disposed waste. This approach is used to reduce solubility of metal hydroxides by
maintaining highly alkaline conditions in the waste (Francis, 1984).
Activated carbon is a possible treatment bed material. It can remove nonpolar organic
compounds from contaminated plumes, but is not practical for the removal of heavy metals.
Activated carbon will not remove polar organics. However, the high cost of activated
carbon, the potential for desorption of adsorbed compounds, and the likelihood of a short
bed-life in the presence of high waste concentrations make the cost of activated carbon beds
prohibitive under most circumstances.
5/93 47
-------
GROUNDWATER CONTAINMENT
Glauconitic greensands have potential for the removal of heavy metals. Bench-scale studies
with leachate indicate that the highest removal efficiencies are for copper, mercury, nickel,
arsenic, and cadmium and that efficiencies increase with contact time (Spoljaric, N.,
Delaware Geological Survey, Newark, DE, personal communication, 1980).
With contact time in the field being on the order of days, metal removal efficiencies may be
extremely high. Experiments indicate that the greensands may also have a high capacity for
heavy metal cation retention, even when flushed with solutions of highly alkaline or acidic
pH (Spoljaric, N., Delaware Geological Survey, Newark, DE, personal communication,
1980).
An in-situ experiment in England (Ross, 1980) demonstrated promising retention capabilities.
Glauconitic greensands appear promising; however, more research is required to determine
their sorptive capacity and capability for treating higher concentrations of heavy metals.
Advantages of glauconitic treatment beds, based on studies to date, include (1) good
permeability, (2) abundance in the Atlantic Coastal Plain (i.e., New Jersey, Delaware, and
Maryland), (3) effectiveness in removal and retention of many heavy metals, and (4) good
retention time characteristics for efficient treatment.
Some disadvantages of using glauconitic treatment beds are (1) unknown saturation
characteristics and potential for plugging over time, (2) potential reduction in pH, (3)
limitations of areas of natural occurrence such as the mid-Atlantic region, and (4) possibility
of land purchase requirements because glauconite is not commercially mined.
Costs
Unit costs in 1985 for the installation of a permeable treatment bed are shown in
TABLE 6. Total closure costs for stabilizing approximately 8,000 cubic yards of
sludge contaminated with nickel hydroxide by covering the site with a 1-inch layer
of calcium carbonate are estimated at $100,000 to $200,000, compared with $900,000
to $1 million estimated for excavation and removal (Francis, 1984).
5/93 48
-------
GROUNDWATER CONTAINMENT
TABLE 6
UNIT COSTS FOR INSTALLATION OF A PERMEABLE TREATMENT BED
Item
Assumptions
Costs
Trench excavation
Spreading
Well-point dewatering
Sheet piling
Walers, connections, struts
Liner
Limestone
20 ft. deep, 4 ft. wide, by
backhoe
Spread by dozer to grade
trench and cover
500 ft. header, 8" diameter,
for one month
20 ft. deep; pull and salvage
2/3 salvage
30 mil PVC
30 mil CPE
Mixed "gravel size" and
"sand size"
Installation (backfill trench,
100 foot haul)
$1.40 cubic yard1
$1/cubic yard1
$115/linear foot1
$7.70/square foot1
$165/ton2
$0.25-0.35/square foot4
$0.35-0.45/square foot
$30-45/ton3
$3.70/cubic yard1
Godfrey, 1984; Costs are total, including contractor overhead and profit.
2Godfrey, 1984; Materials only.
3Schnell, 1985.
4Cope, Karpinski, and Steiner, 1984.
Groundwater Pumping
Description
Groundwater pumping techniques involve the active manipulation and management
of groundwater to contain or remove a plume or to adjust groundwater levels to
prevent formation of a plume. Types of wells used in management of contaminated
groundwater include wellpoints, suction wells, ejector wells, and deep wells. The
selection of the appropriate well type depends on the depth of contamination and the
hydrologic and geologic characteristics of the aquifer.
5/93
49
-------
GROUNDWATER CONTAINMENT
Applications/Limitations
Well systems are very versatile and can be used to contain, remove, divert, or
prevent development of plumes under a variety of site conditions.
Pumping is most effective at sites where underlying aquifers have high intergranular
hydraulic conductivity. Pumping has been used with some effectiveness at sites with
moderate hydraulic conductivities and where pollutant movement is occurring along
fractured or jointed bedrock. In fractured bedrock, the fracture patterns must be
traced in detail to ensure proper well placement.
Where plume containment or removal is the objective, either extraction wells or a
combination of extraction and injection wells can be used. FIGURE 10 depicts the
use of a line of extraction wells to halt the advance of the leading edge of a
contaminant plume and thereby prevent contamination of a drinking water supply.
Use of extraction wells alone is best suited to situations where contaminants are
miscible and move readily with water, where the hydraulic gradient is steep and
hydraulic conductivity is high, and where quick removal is not necessary. Extraction
wells are frequently used in combination with slurry walls to prevent groundwater
from overtopping the wall and to minimize contact of the leachate with the wall to
prevent wall degradation. Slurry walls also reduce the amount of contaminated water
that requires removal, so costs and pumping time are reduced.
A combination of extraction and injection wells is frequently used in containment or
removal where the hydraulic gradient is relatively flat and hydraulic conductivities are
only moderate. The function of the injection well is to direct contaminants to the
extraction wells. This method has been used with some success for plumes that are
not miscible with water.
5/93 50
-------
GROUNDWATER CONTAINMENT
lOa
Cross-Sectional View
Domestic
Well
Extraction Wells
with Rodius of
Influences
lOb
Plan View
FIGURE 10 a-b
CONTAINMENT USING EXTRACTION WELLS
5/93
51
-------
GROUNDWATER CONTAINMENT
FIGURE 11 illustrates an extraction/injection well system for removal. One problem
with this arrangement of wells is that dead spots (i.e., areas where water movement
is very slow or nonexistent) can occur when these configurations are used. The size
of the dead spot is directly related to the amount of overlap between adjacent radii of
influence; the greater the overlaps, the smaller the dead spots will be. Another
problem is that injection wells can suffer from many operational problems, including
air locks and the need for frequent maintenance and well rehabilitation.
Extraction or injection wells can also be used to adjust groundwater levels, although
this application is not widely used. In this approach, plume development can be
controlled at sites where the water table intercepts disposed wastes by lowering the
water table with extraction wells. For this pumping technique to be effective,
infiltration into the waste pile must be eliminated and liquid wastes must be
completely removed. If these conditions are not met, the potential exists for
development of a plume of contaminants. The major drawback to using well systems
for lowering water tables is the continued costs associated with maintenance of the
system.
Groundwater barriers can be created using injection wells to change both the direction
of a plume and the speed of plume migration. FIGURE 12 shows an example of
plume diversion using a line of injection wells to protect domestic water sources. By
creating an area with a higher hydraulic head, the plume can be forced to change
direction. This technique may be desirable when short-term diversions are needed
or when diversion will provide the plume with sufficient time to naturally degrade so
that containment and removal are not required.
Each of the well types used in groundwater pumping have their own specific
applications and limitations. TABLE 7 summarizes the site conditions for which each
of these well types are most applicable.
Wellpoint systems are effective in almost any hydraulic situation. They are best
suited for shallow aquifers where extraction is not needed below 22 feet. Beyond this
depth, suction lifting (the standard pumping technique for wellpoints) is ineffective.
Suction wells operate in a similar fashion to wellpoints and are also depth limited.
5/93 52
-------
GROUNDWATER CONTAINMENT
lla
FLOW
lib
FIGURE 11 a - b
EXTRACTION AND INJECTION WELL PATTERNS
FOR PLUME REMOVAL
5/93
53
-------
GROUNDWATER CONTAINMENT
INJECTION WELLS
FUTURE PLUME MOVEMENT
\
FIGURE 12
PLUME DIVERSION USING INJECTION WELLS
Source: US EPA, 1985a
5/93
54
-------
TABLE 7
CRITERIA FOR WELL SELECTION
•v; ••:..;.;•:' Parameters • /••••:--
Hydrology
• Low hydraulic conductivities
(e.g., silty or clayey sands)
• High hydraulic conductivities
(e.g., clean sands and gravel)
• Heterogeneous materials
(e.g., stratified soils)
• Proximate recharge
• Remote recharge
Depth of Well
Normal Spacing
Normal Range of Capacity
(per unit)
Efficiency
Wellpointe
Good
Good
Good
Good
Good
Shallow <20ft.
5 - 10 ft.
0.1-25 gpm
Good
Suction Wells
Poor
Good
Poor
Good
Good
Shallow <20ft.
20 - 40 ft.
50 - 400 gpm
Good
Ejector Wells
Good
Poor
Good
Good
Good
Deep >20 ft.
10 - 20 ft.
0.1 -40 gpm
Poor
DeepWelis
Fair to Poor
Good
Fair to Poor
Good
Good
Deep >20ft.
>50ft.
25 - 3000 gpm
Fair
o
»
o
8
-------
GROUNDWATER CONTAINMENT
The only advantage of suction wells over wellpoints is that they have higher
capacities. For extraction depths greater than 20 feet, deep wells and ejector wells
are used. Deep well systems are better suited to homogeneous aquifers with high
hydraulic conductivities and where large volumes of water may be pumped.
Ejector wells perform better than deep wells in heterogeneous aquifers with low
hydraulic conductivities. A problem with ejector systems is that they are inefficient
and are sensitive to constituents in the groundwater, which may cause chemical
precipitates and well clogging.
5/93 56
-------
Section 5
-------
RECOVERY PROCESSES
STUDENT PERFORMANCE OBJECTIVES:
At the conclusion of this unit, the participants will be able to:
Briefly describe the advantages of hazardous materials recovery
Briefly describe typical procedures used to recover the following types of
hazardous materials:
Solids on hard surfaces
Liquids on hard surfaces
Solids on surface water
Liquids on surface water
Liquids on groundwater
5/93
-------
NOTES
CAUSES OF CONTAMINATION
• Unintentional Causes
Tank ruptures and punctures
Transportation accidents
Transport line failures
Leaking tanks, pipes, and drums
• Intentional Causes
Illegal discharges
Illegal dumping
RECOVERY PROCESSES
• Reduce the potential for the spread
of the contaminant in the environment
• Reduce the risk of exposure to the
public and the environment
• Reduce cleanup time and cost
SOLID SPILL ON A HARD SURFACE
• Low mobility
• Gravity, terrain, and weather
• Size and shape of solid
• Reactivity with water
• Gas liberator
5/93
Recovery Processes
page 1
-------
NOTES
SOLID SPILL ON OR INTO WATER
• Solubility
Fast or slow, partial or complete
• Insolubility
Floater or sinker
• Time of day and temperature
• Waterway and turbulence
• Tools and equipment
LIQUID SPILL ON A HARD SURFACE
• Reaction to gravity and slope
• Penetration of substrate
• Collection at lowest point
• Reactivity of water
• Solubility or insolubility of water
LIQUID SPILL ON OR INTO WATER
• Solubility
Fast or slow, partial or complete
• Insolubility
Floater or sinker
Time of day and temperature
Waterway and turbulence
Tools and equipment
Recovery Processes
page 2
5/93
-------
RECOVERY PROCESSES
CONTAINMENT OF OIL ON WATER
Most containment devices are designed to hold oil "long enough" for the oil to be removed.
However, no device should be expected to hold oil indefinitely. Depending on the water current,
wind current, and wave heights, long enough might be a few minutes to several days. Because of
the wide variety of water conditions, containment devices can be simple homemade devices or
sophisticated commercial booms and air barriers.
AIR BARRIERS
The use of air or pneumatic barriers has been demonstrated to be an effective means of controlling
the movement of floating products in water with little or no current. Air barriers can be classed as
air bubblers or coherent water jets.
Air Bubblers: The air bubbler is constructed by placing a perforated pipe or manifold in the water
close to the bottom. Injecting air into the pipe causes bubbles to rise from the openings. The rising
bubbles produce a vertical current in the water which causes a horizontal current or water flow on
the surface. This horizontal movement counteracts the forward movement of the oil and prevents
the oil from passing.
Advantages of this system include rapid startup, unrestricted vessel movement, and continuous
operation. There are a number of disadvantages including ineffectiveness in high currents, silting
or clogging of openings, high energy consumption, high initial cost, and system design problems.
Tests under controlled conditions have shown that the excess water at the surface tends to entrain
oil droplets into the water column. This is because the water sets up a recirculating pattern near the
bubble plant (FIGURE 1). When a current is present, the entrainment causes massive oil loss.
Losses occur at current speeds below 0.5 knots (FIGURE 2).
Under ideal conditions (no current or wave action), oil could be contained in areas such as barge
slips with an air barrier. Oil layers up to 5 inches thick could be contained.
Recent experience with air barriers at an angle to the water current have shown them to be nearly
as effective as containment booms. If large debris or ice is present, they may be the only chance
for containment. >
5/93
-------
RECOVERY PROCESSES
BUBBLE PLUME
MANIFOLD
FIGURE 1
AIR BARRIER WITH NO CURRENT
BUBBLE PLUME
FIGURE 2
AIR BARRIER WITH CURRENT
5/93
-------
RECOVERY PROCESSES
Silting of the manifold openings is a problem caused by placing the manifold system too close to the
bottom. Raising the manifold off the bottom may prevent this from happening. Another problem
can be the accumulation of marine growth such as barnacles and seaweed.
The amount of air required to operate a system depends on the length of the perforated manifold,
water depth, opening size, number and spacing of the openings, and the desired surface current.
Systems in the 200- to 300-foot range typically require 400 to 1200 cubic feet per minute, depending
on these variables.
System cost is one of the most prohibitive disadvantages of air barriers. A complete installation can
run as much as $500/foot. Even if a compressor is already available, the cost for an installed
manifold system can exceed $50/foot. Add to this the annual maintenance and energy costs and the
operating expenses become high.
Coherent water jets: One area of new technology in air barriers is the use of coherent water jets.
From above, a concentrated jet of water is directed vertically into the water column, and a large
amount of air is introduced. The air rising back to the surface will act as a typical air barrier. Extra
oil holding ability is produced by the splashing of the water and by a standard headwave that is
created. Tests have shown that the coherent water jets (FIGURE 3) consume less energy than
standard air barriers of equal effectiveness.
WATER
•'. /WATER WITH AIR BUBBLES
FIGURES
COHERENT WATER JETS
5/93
-------
RECOVERY PROCESSES
BOOMS
A boom is a floating barrier designed with sufficient freeboard and draft to contain oil floating on
the surface of the water. Most booms will have the following characteristics:
1. A means of flotation or freeboard to contain the oil and to resist waves
splashing oil over the top.
2. A skirt to prevent oil from being carried underneath the boom.
3. A longitudinal tensile strength member, such as chain or cable, to hold the
boom together and provide a means of anchoring the boom.
4. A ballast to aid in maintaining a vertical skirt orientation.
The following discussion primarily covers typical floating booms similar to the one shown in
FIGURE 4. Fixed barrier booms, supported from the bottom of a channel, will be discussed later.
To be effective, booms must float and be stable in currents, winds, and waves. They should also
be made of materials that are not subject to deterioration from sun, storage, and chemical attack.
Freeboard
Longitudinal Strength Member
FIGURE 4
CROSS-SECTION OF A TYPICAL BOOM SHOWING MAJOR PARTS
5/93
-------
RECOVERY PROCESSES
Oil Carrvunder
Booms will contain oil when placed in quiescent water. If there is only a slight velocity in
the water perpendicular to the boom, and no wind or waves, the boom will still contain oil.
As the current moving perpendicular to the boom becomes greater, forces begin acting on
the trapped oil and cause the oil to escape under the boom. Oil can move under the boom
by two methods, "leakage" and "entrainment". Leakage or sheet breakaway, occurs when
oil builds up to such a depth behind the boom that the oil layer is almost equal to the draft
and escapes under the skirt. Entrainment, or droplet breakaway, involves the carryunder of
oil due to a shearing action at the interface of oil and water at the headwave (FIGURE 5).
The containment effort fails when oil droplets break away from the oil layer and become
entrapped in the flowing water as it passes beneath the boom. The amount of droplet
carryunder is a function of the thickness of the oil layer and the velocity of water. The
phenomenon is related to water velocity and the specific gravity of the oil. Thus, the greater
the velocity or the greater the specific gravity of the oil, carryunder increases.
For a given oil land skirt depth, carryunder will not occur until a critical velocity is reached.
As the velocity increases above the critical velocity, the greater the carryunder will be.
CURRENT
FIGURES
BOOM CONTAINMENT FAILURE CAUSED BY
ENTRAINMENT OF OIL BY SHEARING ACTION
5/93
-------
RECOVERY PROCESSES
Increasing the length of the skirt increases the ability of the boom to retain oil, but the
advantage is not substantial. Disadvantages of a longer skirt are the increases in weight,
cost, and mooring requirements to hold the boom in position. A boom should be effective
regardless of skirt depth when currents are below 0.75 feet per second for a No. 2 oil. For
a No. 6 oil, no droplets are formed if the velocity is less than 0.4 feet per second, but
leakage will occur if the boom has a skirt of less than 12 inches. Therefore, there is no
advantage in making the skirt length greater than 12 inches to prevent the movement of oil
beneath a boom in slow-moving waters. A longer skirt is required in rough waters.
Oil Splashover
Although a properly deployed boom can minimize carryunder, it may be subject to another
form of failure, "splashover." Splashover will depend on the basic boom design, freeboard,
angle of the waves to the boom, wave heights, and distance between successive waves. No
boom will be capable of holding oil under all sea conditions, but some boom designs are
more effective than others. Under slow swell conditions in the open ocean, most booms will
be flexible enough to conform to the waves. Under choppy conditions, it is difficult to keep
oil from splashing over the boom. Such conditions require a boom with a relatively high
freeboard and long skirt, but even that type may still be ineffective.
BOOM DESIGN
General Criteria
A bigger boom is not necessarily a better boom except for the advantage of
preventing oil splashover in waves. Booms can be classified as round, fence,
inflatable, or self-inflating (FIGURES 6, 7, 8, and 9). Each boom has specific
advantages and disadvantages.
Booms are available in different lengths. For spills in creeks and rivers, lengths of
100 and 200 feet are recommended. Each section of boom should be supplied with
connector to extend the length as required.
Anchor points should be constructed in the boom at several places along the length.
A maximum distance of about 100 feet between anchor points is acceptable, with a
50-foot spacing preferable. Some booms are designed with handles to assist in
deployment and recovery. Bright colors such as international yellow or orange make
booms more visible, whereas dark-colored booms are difficult to see, particularly at
night. Dark-colored booms can cause problems for the cleanup personnel and may
present a navigational hazard.
Several pieces of auxiliary boom equipment are important, such as line, tow bridles,
boat attachments, anchor sets, floats, shovels, pipes, and a sledge hammer. Much
of this equipment will be used in the field exercises on boom development.
5/93 8
-------
RECOVERY PROCESSES
Self Contained
Float
Ballast Bar
&
Cable
FIGURE 6
TYPICAL ROUND BOOM
Possible Advantages
1. Good wave
conformance in chop
and swell
2. Inherent reserve
buoyancy
3. Tows well
4. Allows bottom tension
design
5. Floats with punctures
Possible Disadvantages
1. Bulky to store
2. Not as easy to clean
3. Floats can be
damaged
Representative Types
1. Kepner
2. Slickbar
3. Acme
4. Bennett
5. American Marine
6. Containment Systems
7. Parker Systems
8. Texas Boom
9. Abasco
10. American Boom and
Barrier
11. Skimmex
12. Versatech
5/93
-------
RECOVERY PROCESSES
FIGURE?
TYPICAL FENCE BOOM
Possible Advantages
1. Easy to store
2. Abrasion resistant
3. Good freeboard
performance
4. Can be stored on reels
5. Low cost
6. Light for its size
Possible Disadvantages
1. Twists and corkscrews
in wind and current
(some models)
2. Poor towing
characteristics (some
models)
3. Poor wave conformity
4. May require stiffeners
that can chafe or
break
5. Little reserve
buoyancy
Representative Types
1. Navy boom
2. Uniroyal
3. Bennett
4. Oilfence
5. Goodrich
5/93
10
-------
RECOVERY PROCESSES
Rubber Impregnated
Nylon Fabric
Inflation Point
Hollow Inflation
Chamber
FIGURES
TYPICAL INFLATABLE BOOM
Possible Advantages
1. Easy to store
2. Made in floating-
sinking configuration
3. Good wave
conformity
4. Easy to clean
5. Small storage space
requirements
Possible Disadvantages
1. Requires inflation
prior to use
2. Requires deflation
after use
3. Subject to puncture
4. Expensive
5. May have valve
problems in freezing
temperatures
Representative Types
1. Vikoma
2. Goodyear
3. Ro Boom
5/93
11
-------
RECOVERY PROCESSES
Airtight
Bulkhead
Hoop
Buoyancy
Chamber
(Deflated)
FIGURE 9
TYPICAL SELF-INFLATING BOOM
Possible Advantages
1.
2.
3.
4.
5.
Easy to store
Compactable
Easy to tow
Self-inflating
Good wave
conformity
1.
2.
3.
4.
5.
Possible Disadvantages
Complex design
Subject to puncture
Subject to physical
damage
Expensive
May have valve
problems in freezing
weather
Representative Types
1. Kepner
2. Bennett
3. Expand!
5/93
12
-------
RECOVERY PROCESSES
Any boom will normally fit into one of the four previously mentioned general
categories. However, some booms, that might fit into one of these four categories
often distinguish themselves from the others by distinct designs or other features.
For example, the Oilfence, generally considered a fence boom, is unique with its
folding "paddle" flotation units (FIGURE 10). The boom has some of the generic
advantages associated with the typical fence boom. Distinct advantages include the
relative ease with which the boom can be stored, deployed, and cleaned. Also, the
outrigger flotation units provide extra stability. This boom has an extraordinary
amount of freeboard to help minimize splashover. Possible disadvantages include
added complexity and more parts subject to damage, although experience has not
shown this to be a problem. This design will twist in high currents and has caused
problems when tug boats are used close to the boom.
BARRIER
VERTICAL STABILIZERS
BOTH SIDES
FIGURE 10
OILFENCE BOOM
Most boom manufacturers offer at least one type of high-current boom (FIGURE
11). This option consists of a round boom with a short, solid containment skirt.
Below this short containment skirt, the boom has a large, open-weave mesh or net.
The netting, which allows water to pass through while the solid skirt material remains
near the surface, is designed to contain the floating product. Distinct advantages
include the boom's ability to remain stable in swift currents and to substantially
reduce the current load on the boom in high currents.
5/93
13
-------
RECOVERY PROCESSES
FIGURE 11
HIGH-CURRENT BOOM
Floats
Boom floats should be made of solid, rather than granular, material so that a puncture does
not result in loss of flotation. The floats should be constructed in relatively short segments
to better conform to waves. Detachable floats are easy to repair but can be ripped from the
skin. Floats within the skirt material eliminate metal or plastic connector straps but make
replacement or repair difficult. A round shape features a built-in reserve buoyancy and is
more common than a square or rectangular shape. The shape and size of the float can have
a significant effect on the ease of deployment and use. Inflatable floats are subject to
puncture and valve malfunction but are very lightweight and flexible.
Tension Member
Nylon belting is strong but may stretch more than other parts of the boom. Should this
occur, the parts that stretch less could break. For light service and short lengths, elaborate
tension members may not be necessary.
5/93
14
-------
RECOVERY PROCESSES
Cables in a pocket of fabric or attached to the outside of the boom corrode and break or fray
and become dangerous to personnel handling the boom. Chains in pockets chafe the fabric
and eventually wear through unless the fabric is reinforced, which requires more time and
expense.
Booms are available that use the fabric of the boom as the only tension member. This
arrangement solves most of the problems associated with other types of tension members,
except that these high-strength fabrics are more expensive than the average boom fabric, and
high tensile strength does not necessarily mean that the fabric has higher tear strength.
Ballast
Ballast should be attached to a boom so that it does not shift or chafe the skirt. Multi-
metallic fasteners promote electrolysis and subsequent corrosion. The ballast should be non-
sparking and be heavy enough to keep the skirt nearly vertical in unexpected currents. Some
boom designs with stiff fabric and stable flotation do not use ballast.
Skirt
The skirt should be made of durable material that does not tear easily and resists chafing.
The skirt should be designed to be compatible in depth to the float. In any case, a skirt
length over 18 inches is rarely justified. The owner's name should be stenciled on each
section of boom or otherwise marked for easy identification to avoid confusion when more
than one company supplies booms for cleanup.
Skirts can be formulated or coated with an antifouling agent to retard marine growth if they
are to be left in the water for long periods.
Methods of Connection
An ideal connector is one that could be used by one man from a small boat, is uncomplicated
and quickly connected, would not have any small parts that could be lost overboard, would
be leak-proof (close-coupled) and be of a unisex design. ASTM developed a standard
connector based on the design of the Slickbar Slickhitch. If several booms are used from
different manufacturers, it is recommended that adapters be available to facilitate connection.
BOOM DEPLOYMENT
To direct an effective cleanup operation, a supervisor must know what factors govern boom
operation and understand how to minimize the amount of oil that splashes over, or goes under, a
boom. The three factors that affect oil containment by booms are:
1. Boom design
5/93 15
-------
RECOVERY PROCESSES
2. Characteristics of the oil
3. Positional method of boom deployment.
Obviously, the cleanup crew has no control over the type of oil spilled. When a spill occurs, the
cleanup crew must use the available equipment. The first two factors listed above should be
considered when acquiring a boom. Booms that are purchased should be compatible with the type
of oil that may be spilled and with design features that work well in the stream, river, or other type
of water body at a particular facility. After a spill occurs, the cleanup crew has only the third
variable to use to its advantage.
As discussed previously, oil carryunder will decrease as the velocity of the water perpendicular to
the boom decreases. In currents above 0.5 knots, the only way booms can be used effectively is by
placing them at angles to the current. For any given stream condition, the velocity perpendicular
to the boom will depend on how the cleanup crew angles the boom to the current. FIGURE 12 is
a guide for selecting angles for use in various currents. The figure is based on a maximum water
velocity perpendicular to the boom of 0.7 knots. For example, if the velocity of the current in a
stream is 2 knots, the boom should be set at a 24 degree angle with the bank.
o
SC
l_
o
o.
"
c
o
D
"a
10 2O X> *O SO 6O 70
Boom Angle to Bank in Degrees
80 9O
FIGURE 12
BOOM ANGLES FOR VARIOUS CURRENTS
5/93
16
-------
RECOVERY PROCESSES
The force on a boom caused by the current is significant. The force can be calculated using the
following formula:
Fc
Vc
Fc = 1.92 X (Vc)2 X Dft
Force due to current in pound per linear foot of boom
Current velocity in feet per second
Boom skirt depth in the water in feet.
In a worst-case scenario where the boom is placed perpendicular to the current, the load on ropes
and anchors can be calculated. For example, if 500 feet of a 24-inch boom that has a 16-inch skirt
is stretched across a stream which has a 2.11 feet/second current, the equation estimate would be:
Fc = 1.92 x (2.11)2 x 1.33
F,. = 11.371bs/foot
|oul
11.39x500 ft. = 5,685 Ibs.
Although this figure represents the worst case, it is useful in planning the types of anchors, ropes,
and boats that could be needed during a spill (TABLE 1).
TABLE 1
CURRENT LOAD IN POUNDS PER LINEAR FOOT OF BOOM
FOR VARIOUS SKIRT DEPTHS
Current Speed
Knot
0.5
1.0
1.5
2.5
Ft. per Minute
51
101
152
253
Ft. per Second
0.84
1.69
2.53
4.22
Skirt Depth
6"
0.68
2.74
6.15
17.10
12"
1.35
5.48
12.29
34.19
24"
2.71
10.96
24.56
68.33
5/93
17
-------
RECOVERY PROCESSES
The wind force can also add to boom loading, but compared to current, wind is usually negligible.
In high winds, it is unlikely that a boom will be effective because of large waves. Also, personnel
safety and equipment damage are concerns. Wind force can be calculated with the following
formula.
Fw = .00339 x Vw x Hft
Fw = Force due to wind in pounds per linear foot of boom
Vw = Wind velocity in knots
Hft = Height of boom above the water in feet.
Approximate Safe Working Loads/Tensile Strengths of New Rope
Rope Manilla Nylon Polyester
Inches Pounds Pounds Pounds
Diameter tt\ (3 Strand) (3 Strand) (3 Strand)
5/16 200/1000 500/2500 500/2500
3/8 270/1350 700/3500 700/3500
7/16 1140/5700
1/2 530/2650 1250/6250 1200/6000
5/8 880/4400 2100/10500 1950/9750
3/4 1080/5400 2750/5400 2300/11500
Towing load can be significant when a boom is anchored on one end and pulled against the current.
Boats must have sufficient horsepower and be properly rigged to tow. Lines must be capable of
withstanding the forces, and the boom must have a tension member capable of high loads. If the
boom is extended behind the tow boat and pulled free in the current, there is only the frictional drag
along the boom. Because this drag is a function of boat speed, proper motor size becomes a function
of boom size and length, boat size, and water velocity. Although free towing drag is low, when one
end. of the boom is anchored to the shore, a small boat may be incapable of positioning the boom
because of the high current drag exerted on the boom. The boom must also be able to withstand the
forces. The tension member must not become detached from the boom becuase of differential
expansion.
5/93 18
-------
RECOVERY PROCESSES
Attempting to moor a boom in a straight line across a current (i.e., 90 degrees) is not recommended.
The result is a sag in the boom that will trap free-floating oil at a point inaccessible to the shore.
In swift currents the resulting forces on moorings can cause large lines to break and present possible
safety hazards. The current can be so swift that the boom may tend to dip and become completely
or partially submerged. If this happens, the boom's position should be readjusted. The total force
on the moorings points will be a combination of the forces caused by currents, wind, and waves.
Boom positioning is an important subject. The first step is to decide where the boom should be
located. It is likely that the boom would be positioned on an angle to the current; therefore, the
prime concern becomes the location of the upstream end. If the selected upstream location is
inaccessible, a spot farther upstream can be used for access, and the boat and boom can be allowed
to drift to the selected mooring location. The boom may be secured to trees, stakes, anchors, or
other solid objects.
Unless there is little or no current, there will always be a sag in the boom. The objective is to
reduce the sag sufficiently to provide easy collection access. Intermediate anchor points may be
needed to lessen the load on the end mooring points and to reduce the sag.
FIGURE 13 shows a typical mooring setup with anchor, chain, rope, float, and boom. The chain
acts as a shock absorber, provides ballast, and keeps a low angle between the bottom and the anchor
line. The float keeps the end of the boom from being submerged.
Float
Anchor Line
Recommended Length
5-10 ft. Water Depth
6 Feet of Chain
Anchor
Danforth
Type Anchor
FIGURE 13
TYPICAL MOORING SETUP FOR A BOOM
5/93 19
-------
RECOVERY PROCESSES
A practical boom location will meet the following criteria:
1. Accessible by truck or boat so that the cleanup crew can collect and remove
the oil
2. In the path of the oil so that the oil will be intercepted
3. Have low to moderate currents, which will facilitate handling and collection
and reduce stress.
Spills in Creeks
Deep draft booms should not be used for spills in shallow creeks, streams, or ponds. They
may be ineffective because they act as a dam, causing the boom to lie flat or to back up the
water to such an extent that it overflows the boom. If the water is too shallow, the stream
might be deepened by using a dragline or backhoe, or by constructing a temporary dam
downstream. These techniques may require permission of local or state agencies. This
equipment can also be used to dig an oil collection pit (FIGURE 14). Oil can be directed
by a boom to the pit for recovery.
OIL COLLECTION
PIT
SPACE OIL BOOM
4 FT. APART
FIGURE 14
OIL COLLECTION PIT SHOWING BOOM PLACEMENT
5/93
20
-------
_ RECOVERY PROCESSES
Alternatives to expensive commercial booms may be field fabricated. These "homemade"
booms use similar designs as commercially available booms, but instead of plastic and
rubber, are made of materials such as fiberglass, plywood, metal sheeting, or metal flashing.
One simple design uses metal roll flashing with 1x2x4 foot floats alternately spaced
about 16 inches apart (FIGURE 15).
FIGURE 15
METAL FLASHING BOOM
NOTE: Floats should be sufficient to provide adequate flotation and attached above the
midpoint of the flashing.
Another device that can be used as a boom consists of wooden or metal stakes driven into
the ground and spaced across a water body. Board, planks, or metal sheets can be nailed,
bolted, or tied to the stakes at the surface to contain oil (FIGURE 16). If sorbent is placed
ahead of the dam, a sorbent filter fence has been created.
Another kind of filter fence may be constructed by using chicken wire and stakes with
synthetic sorbents or loose straw upstream of the fence. The fence should be constructed
perpendicular to the current so that the sorbent will remain distributed along the entire length
and not be carried to the edge of the creek. For very small creeks, a log can be placed
across the water. Sorbents can be placed ahead of the log.
5/93
21
-------
RECOVERY PROCESSES
FIGURE 16
WOODEN FENCE BOOM
In small creeks a dam might be constructed with an underflow pipe or conduit (FIGURE
17). This design consists of a length of pipe or culvert placed parallel to the direction of
water flow with the upstream end lower than the downstream end. The dam can be
constructed with a shovel, dragline, backhoe, or bulldozer. The objective is to pass water
through the pipe, but retain the floating oil. The pipe must be large enough to allow water
to pass without backing up to a depth greater than the dam. Several pipes at various depths
or side by side may be used in the dam to carry the required flow. An alternate method is
to add a valve downstream on a level pipe to control the water flow.
Culverts in a creek will serve as a barrier for oil if the entire culvert is below the water
surface. Existing culverts can be used at some locations along a creek by damming the creek
downstream and thereby raising the water level above the top of the culvert.
5/93
22
-------
RECOVERY PROCESSES
OIL
FIGURE 17
UNDERFLOW PIPE DAM
Spills in small creeks and ponds can also be contained by dams built of hay bales. The bales
should be placed touching each other and perpendicular to the flow to contain and sorb the
oil. Bales must be removed and disposed of as necessary. Hay bales are very heavy when
soaked with oil and water and may present a handling and disposal problem.
Spills in Rivers
River spills may require more than one boom because strong currents or turbulence may
cause oil losses beneath the boom. Booms should always be angled; otherwise, a pocket will
be formed in the center of the river and the loads can be excessive on the boom, mooring
lines, and anchors (FIGURE 18). Booms deployed completely across a river will hamper
boat and ship traffic. Remember, oil slicks moving down a river will eventually drift to
either side of the channel.
5/93
23
-------
RECOVERY PROCESSES
OIL
OIL
BOOM
FIGURE 18
BOOM FAILURE DUE TO IMPROPER DEPLOYMENT
The tendency of oil to accumulate naturally in certain areas can be taken advantage of by
placing several booms at strategic points along the river (FIGURE 19).
CONTAINMENT BOOM
BACKUP BOOM
FIGURE 19
BOOM LOCATION ALONG THE OUTSIDE BENDS IN A RIVER
5/93
24
-------
RECOVERY PROCESSES
Strategic locations can be the wide places in the river (pools) where the current speeds are
lower and booms are likely to be more effective. Bends are also convenient places in the
river where the floating oil can be more easily intercepted.
Booms used in rivers usually do not need a skirt deeper than 12 inches. However, floating
debris is a problem in large rivers. Debris can destroy booms and release oil already
contained. It may be necessary to keep a patrol boat upstream of booms to protect them
from floating objects. Debris booms may also be required (FIGURE 20).
FIGURE 20
DEBRIS BOOM MADE OF LOGS WITH CHAIN OR
CABLE STRUNG THROUGH A PIPE
Spills in Lakes, Estuaries, and Bays
Containment of oil on lakes and bays is complicated by the special problems caused by river
currents, boat traffic, wind, and tides. Changes in wind velocity and direction will affect the
movement of oil.
5/93
25
-------
RECOVERY PROCESSES
FIGURE 21 illustrates the steps that can be taken to contain an oil spill in a lake or bay.
After the cleanup crew deploys a boom at the proper angle downstream from the spill (step
1), a second boom is deployed as a backup in case any oil flows from wind-generated
currents (step 2). A third boom is deployed upstream of the first to completely contain the
spill (step 3). As the oil is skimmed from the pocket, the boom crew can begin taking in the
boom to reduce the size of the pocket and contain the oil in a smaller area.
Wind'*5*
Wind
FIGURE 21
BOOMING A SPILL IN WINDY CONDITIONS
Spills in the Ocean
The most common approach for containing ocean spills utilizes large booms with ocean-going
skimmers (see the section on skimmers). Large, strong booms are needed for this type of
service. Many booms designed for offshore use are inflatable. Deployment time is not
greatly increased with inflatable booms. Inflation usually takes place automatically with
deployment. Some inflatable booms are fabricated of vulcanized, rubber-coated fabric which
is sturdy and shows good tensile strength, tear strength, abrasion resistance, and puncture
resistance.
5/93
26
-------
RECOVERY PROCESSES
Storing and Cleaning Booms
Booms can be stored in several places. A convenient storage area is on the deck of a boat
so that booms can be deployed as needed. Booms can be stored on a dock or barge and
pulled into the water using a ramp or roller, which provide some protection from wear and
tear. Booms may also be stored in the water by attaching segments to anchors. Considerable
lengths of booms can be stored in the water in a small area by folding sections back and forth
similar to the way fire hoses are stored on trucks. One major disadvantage to this storage
method is the formation of marine organisms on the boom which add weight and drag.
Booms can be cleaned by separating the boom into sections and laying each section out on
a clean, sloping surface. Oil can be removed by washing the boom with water and steam
spray. The boom washing area should direct the washwater to a sump where the oil can be
collected. Cleaning a boom coated with heavy layers of viscous oil may be a time-consuming
and expensive process.
SUMMARY
Containment devices are designed to contain oil floating on the surface of water. A properly
installed containment device should contain the oil and cause the oil to move to a selected location
where it can be removed from the water surface. Air barriers use currents and a mound of air and
water generated by air bubbles to contain oil. They work best in little or no currents.
Barriers constructed of sorbent materials can be effectively used in creeks. Dams and culverts are
also useful in stopping the movement of oil slicks. Series of booms are normally used in spills in
rivers and other large bodies of water because it is difficult to contain or divert large spills with one
boom, especially when high currents are involved.
Booms are often stored on the deck of a boat or barge, which facilitates deployment. Booms are also
stored on docks, and a ramp or roller can be used to assist in launching and recovery.
BOOM SELECTION CHECKLIST
1. Booms should be operational in waves with height-to-wavelength ratios of 8 to 1. Booms
should work in winds equal to a Beaufort Force 5.
2. At an effective current velocity of 0.7 knots, the skirt should remain within 20 degrees of
the vertical.
3. The boom should be capable of being deployed at a 5 knot rate.
5/93 27
-------
RECOVERY PROCESSES
4. The boom should be capable of being towed at 10 knots in a straight line without twisting.
It should not twist when being towed behind a maneuvering tow boat at 2 knots.
5. Sections should be capable of being connected and disconnected, without nuts and bolts or
tools, from a small craft in not over 2 minutes.
6. Recovery and storage should be able to be accomplished by three or less personnel.
7. In calm water, the boom should have a freeboard of at least 41A inches.
8. The boom should allow 180 degrees folding at least every 10 feet of length or less.
9. The boom should have reserve buoyancy of at least 200 percent. The buoyancy should
double within 18 percent of the normal water line.
10. The boom should have at least a 0.2 percent UV oxidizer/inhibitor coating or be capable of
withstanding 2 years of continuous exposure to direct sunlight.
11. The flotation should have a smooth surface and must be puncture resistant.
12. Puncturing or cutting of a foam float section should not significantly reduce flotation or allow
escape of flotation.
13. The flotation should be an integral part of the entire boom.
14. Flotation should be closed-cell, foamed plastic resistant to hydrocarbons. Granular type
flotation material is not recommended.
15. The color should be international orange or yellow or another bright color. (Some locations
use orange to identify medical waste. This color may become a poor choice for pollution
control equipment).
16. Skirt fabric should show good break strength and abrasion resistance and be oil resistant.
17. The base fabric for the skirt should be high strength and UV stable.
18. No laminated materials should be used in the skirt.
19. Stiffeners should not rust and should not wear through or puncture the fabric after use in the
water with normal wave action.
20.' The boom should be capable of a direct tensile load, end-to-end, of not less than 3,000
pounds.
21. The primary tension member should not elongate more than 10 percent at 60 percent of its
ultimate tensile strength.
5/93 28
-------
RECOVERY PROCESSES
22. Tension members should be attached to the boom flotation at no less than six points every
10 feet.
23. Tension members should not be located where they would prevent the freeboard from
remaining vertical when the boom is used perpendicular to a 0.7-knot current.
24. Ballast must be nonsparking. If cable or chain is used, it should be designed to prevent
chafing.
25. The ballast should not collect static electricity.
26. For a 0.7-knot current, the following minimum ballasts are recommended per linear foot of
boom:
Skirt Depth
6"
8"
10"
12"
Ballast Ibs/ft of boom
0.33
0.44
0.54
0.75
27. The ballast should not be rigid for more than 4 inches in any one piece.
28. Anchor points should be placed every 100 feet on both sides and directly connected to the
tension member.
29. End connectors should not permit oil leakage.
30. End connectors constructed of metal should only use stainless steel, anodized aluminum, or
other strong noncorroding material.
LIST OF COMMON BOOMS
The following list of boom types is intended as a guide for the trainee and is not for the purposes
of recommending a particular brand. Because of space limitations, not all types are included in the
list. If a type is not included, this does not mean that the boom should not be used. The following
classification system can be used to distinguish among booms appropriate to inland water, bay and
ocean service based on freeboard and draft.
Classification
Service
Freeboard
Draft
I
II
III
Inland Water
Bay
Ocean
4-10'
10-18'
£18'
6-12'
12-24'
^24' & above
5/93
29
-------
RECOVERY PROCESSES
CONTAINMENT AND RECOVERY OF OIL ON GROUNDWATER
Although spilled oil may adhere to soil particles, roots, and rocks, changes in land geology or water
regimes can cause trapped oil to enter groundwater. In other cases, spilled oil easily penetrates the
soil to contaminate groundwater. Because oil on groundwater weathers and degrades slowly, if at
all, oil can affect potability and its use in industrial processes for decades or centuries. This is
important because about one-half of the population of the United States depends on groundwater for
drinking water (primarily the small- to medium-sized communities and farms).
Many large groundwater spills have been well publicized. For example, a refinery in Brooklyn,
New York, apparently had tanks, pipelines, or valves leaking for years. Approximately 20 million
gallons of petroleum distillate was estimated to be under 70 acres of industrial and residential
property. During the first year of cleanup, 95,000 gallons was recovered. Oil recovery will take
years. An estimated $3 million to $4 million will be spent on recovery and cleanup.
Small spills can also influence groundwater use until the oil product has been removed. This section
will discuss groundwater oil movement, groundwater monitoring, oil containment, and oil recovery
techniques.
OIL ON GROUNDWATER
When oil penetrates the subsoil to the groundwater or aquifer, the oil can move on top of the
groundwater by spreading and by groundwater flow. The water table is that level of the water
observed in wells. However, in soils, water can rise above the water table by capillary action. Just
as the liquid level will appear higher in a straw, or the corner of a towel will transport water into
a towel, water will fill spaces in the soil above the water table. Oil entering this water will spread
and move on the capillary fringe (FIGURE 22). The capillary fringe can vary from 3 to 72 inches,
depending on soil pore geometry. Permeability indicates a soil's ability to allow fluids to pass from
one space in the soil to other spaces in the soil. Larger spaces due to large soil particle size have
higher permeability; therefore, low permeability may be one-half inch per year and high permeability
several feet per year.
5/93 30
-------
RECOVERY PROCESSES
MNSATURATED
• ' SOIL '•
CAPILLARY
FRINGE
SATURATION LEVEL (WATER LEVEL)
« WATER FLOW
FIGURE 22
OIL ENTERING GROUNDWATER (horizontal view)
At first, oil thickness increases under the influence of continued descending oil. The force or
pressure exerted by the accumulation of oil will displace water in the capillary fringe and possibly
in the groundwater. As gravity influences the oil to spread and the pressure is released, the
groundwater returns to its former level. In a uniform soil (all gravel, sand, or silt), oil will spread
and move with water flow and form an egg-shaped oil plume (FIGURE 23).
g;^^
S:-:-:v^^?PS^
FIGURE 23
OIL ON GROUNDWATER (tangential view)
5/93
31
-------
RECOVERY PROCESSES
If the oil comes into contact with a different size soil particle layer or rock fissure, it will change
the oil spreading pattern. An impermeable layer would not only change the shape of the plume, but
also change the direction of oil flow (FIGURE 24).
AFTER FLOW
FIGURE 24
OIL ON GROUNDWATER WITH IMPERMEABLE LAYER
As oil flows come oil (25 to 40 percent) will fill pore spaces, adhere to soil particles and rock
surfaces and become immobile, while soluble oil components can mix into the groundwater. If
enough oxygen is available, slow bacterial and/or chemical decomposition can occur. In some cases,
decomposition increases water-soluble components up to 10 times. The factors that affect oil
movement on groundwater are many, they often interact with each other. However, oil spreading
can be estimated using the following formula:
Where:
S
V
A
R
D
K
R and F values are listed in TABLE 2.
S = {(1000)(V) -
maximum spread of oil on the water table in m2
volume of infiltrating oil in m3
area of infiltrating at surface in m2
retention capacity of soil above water table in liters/m3
depth of water table
the approximate correction factor in various oil viscosities:
K for gasoline = 0.5
K for kerosene = 1.0
K for light fuel oil = 2.0
oil contained above capillary fringe in liters/m2.
5/93
32
-------
RECOVERY PROCESSES
TABLE 2
R and F VALUES FOR VARIOUS SOIL TYPES
""'•••: •''•:'< : ' • •:'"•.'.'•: cr\n ''•''•' : ' .•'"' '•'.•:- •.'•"*<••' ' .•••;"
••• ... . • .. ••: - ;.- • ' -SOIL . V- ... ••" -;,: .... : . '• :\.-::'
Stones, coarse gravel
Gravel, coarse sand
Coarse sand, medium sand
Medium sand, fine sand
Fine sand, silt
'"•••(: R -^
5
8
15
25
40
' ' F' .
5
8
12
20
40
In using this formula, inherent errors in data can result from seasonal water table fluctuations and
by underestimating or overestimating D (the depth of groundwater). Also, oil thickness on the water
table is not the same as oil thickness measured in wells. In some fine sand or silty soils, oil in a
well might be lower than oil on the groundwater. This is due to a break in the capillary fringe
caused by the well. However, the thickness of the product in a well is more of an indication of the
rate the product moves through the soil or the position of the well in the plume.
The movement of oil due to groundwater flow can be estimated by the following equation:
Where:
Q
p
h,
h2
L
Q =
flowrate of groundwater in m'/day/m
permeability in m/day
height of groundwater
height of groundwater
length or distance between h, and h2
Both of the estimates are usable for shallow groundwater problems or initial planning for deep
groundwater problems. However, in deep groundwater problems, before time and money are spent
on containment and recovery techniques, a monitoring system should be initiated to delineate plume
characteristics and to aid in effective containment and recovery.
5/93
33
-------
RECOVERY PROCESSES
OIL IN GROUNDWATER MONITORING
The first step in successful groundwater monitoring is the preliminary investigation. The following
information sources can be used: U.S. Geologic Survey maps and tables, Soil Conservation Service
maps and tables, state geologic surveys, water resource personnel, university geology departments,
city water department maps and personnel, past oil company personnel or companies that have drilled
in that area, and consultants. The information gathered can help determine:
1. Groundwater flow characteristics
2. Aquifer to surface water boundaries
3. Recharge areas
4. Local abstraction points (i.e., city groundwater wells)
5. Flow mechanisms through fissured or highly permeable zones.
The second step in successful groundwater monitoring is field investigation. This investigation may
include soil samples, water samples, or other hydrogeologic tests. Soil samples may be examined
for grain size to accurately define the nature and location of the soil horizons. The porosity of each
soil horizon can also be determined from core samples. Boreholes may be used for water
permeability measurements. In addition, hydrocarbon percolation tests may be performed. The
groundwater head distribution may be studied by inserting standpipes (for monitoring the water level)
into the completed boreholes. Ground-penetrating radar can be used to define geologic sequences,
investigate fractures, and locate buried objects. Electromagnetic frequency techniques can
graphically show horizontal and vertical characteristics such as aquifer boundaries and geologic
interfaces. Both of these latter methods can improve mapping of oil plumes over plume estimates
from just drilling wells. Use of these methods, in some cases, may prevent unnecessary drilling.
With some highly volatile products, the spread of the plume can be monitored by the vapors
migrating through the soil surface. Although presence of vapors in basements, in oil wells, in
trenches, and along disturbed soils (i.e., buried pipelines) can indicate where the oil is, the absence
of vapors does not indicate that the oil is not present. Shallow boreholes and hydrocarbon monitors
or explosimeters can help identify vapor penetration.
Field investigation may also include choosing a water sampling program. A water sampling program
may involve drilling wells, performing water and soil analysis, and/or conducting mathematical
modeling to estimate plume size and oil movement.
Generally, monitoring wells can be classified into three types: (1) a piezometer, (2) an observation
well, and (3) a pumping well. A piezometer is a small-diameter well that is tightly sealed so that
detection of static pore water pressure can be used to determine the true direction measured of
groundwater flow. More than one piezometer can be installed in a well boring by sealing
piezometers at different depths from each other. Piezometers can be either pneumatic or electric.
An observation well is larger in diameter than a piezometer well and is used to measure oil/water
levels. Observation wells have been used to determine the direction of groundwater flow by injecting
a tracer such as fluorescein, Rhodamine WT, or salt water among a number of observation wells.
5/93 34
-------
RECOVERY PROCESSES
A pumping well is the largest in diameter of the three types of monitoring wells. Pumping wells are
used to introduce pumps or other equipment. Water samples can be obtained from observation and
pumping wells. However, certain problems may arise in each well type.
The type, as well as the placement, of a well is important. Permission must be obtained from those
individuals or companies that have surface and mineral rights. The location of underground
structures such as gas, petroleum, or water pipelines; powerlines; telephone lines; sewer lines; and
storm sewer lines should be identified and visibly marked.
Monitoring wells should be placed in a downgradient direction to the flow of groundwater and spaced
far enough apart to determine plume size. At least one well should be drilled upgradient to ensure
that oil was not missed. Monitoring wells should be used to confirm the preliminary findings.
Some situations can complicate groundwater monitoring and oil recovery. One of the more difficult
situations involves a land spill on or into bedrock. The oil moves into fissures and crevices and
along joints of bedded rock and bedding planes. The upper layers of limestone, basalt, and
sandstone usually show pronounced Assuring, especially if the area is in a zone of tectonic
disturbance. Predicting the underground movement of oil in such areas is quite difficult. Spilled
oil may follow fault lines in the direction of their dip. Sometimes recovery wells may be drilled
along a fault line to intercept the spilled oil (FIGURE 25). This technique in particular requires
sound geological information before attempting any drilling operations.
PERVIOUS LAYER
IMPERVIOUS LAYER
:
FIGURE 25
RECOVERY WELL ALONG FAULT LINE
5/93
35
-------
RECOVERY PROCESSES
Wide fissures, crevices, and solution channels may be present in limestone and gypseous and
saliferous rock (FIGURE 26). Solution cavities may hold hydrocarbons for years, releasing them
only in times of drought or flood. In central Pennsylvania in 1958, 50,000 gallons of crude oil was
lost in a limestone terrain honeycombed with solution channels. Recovery wells were drilled and
much of the product was retained on the site. However, in the mid-1960s a drought caused the water
table to drop and oil stored in the limestone was released, causing water well contamination. The
problem persists today.
One method used in such areas to trace dispersion direction is fracture trace analysis. Air photo
interpretation is used to find the major fractures that could be transporting the spilled product.
Observation wells may then be drilled to locate the oil.
. ' " • PERMEABLE SOIL
•.'"."•.••,-.
' SINKHOLE • . . '•
', 'I "
. LIMESTONE
'- ,
- 'TRAPPED OIL
SOLUTION CHANNEL WATER MOVEMENT
FIGURE 26
SOLUTION CHANNELS IN LIMESTONE
These combined data offer a working knowledge of.
1. The amount of hydrocarbon that must be spilled in order to reach the
groundwater
2. The direction and rate of migration of the product once the groundwater is
contaminated
3. The geological or hydrogeological boundaries that exist
4. The rate at which the product may be extracted from the ground.
5/93 36
-------
RECOVERY PROCESSES
This information can be translated into a cross-sectional map showing the probable direction of travel
of the oil as it follows the groundwater system (FIGURE 27).
RAINFALL
I
.WELL
SPRING
STREAM
l_LJ_i ••'• i •
WATER TABLED'I.'
FIGURE 27
SAMPLE GROUNDWATER SYSTEM
SAMPLING DEVICES FOR MONITORING WELLS
Sampling devices may be as simple as an observation well with oil-finding paste on a stick or as
complex as intricate well casings that are designed to take samples and pressure readings at various
depths. Although existing wells may be used, data analysis can become complicated. Drilling fluids
can change the chemical or biological well environment, water from several aquifers can flow into
a single well, surface contamination into a well can occur, and casing materials and pumping
equipment can contaminate sampled water. High concentrations of oil in groundwater may not
require great accuracy in measurements, so polyethylene pipe casings can be used. However, when
accurate samples are needed, a number of factors should be considered when choosing materials.
5/93
37
-------
RECOVERY PROCESSES
1. Metal surfaces can catalyze certain chemicals (i.e., iron)
2. Lubricants from pumps, oils on pipes, and glues from pipe joints can
contaminate samples
3. Plastics in pipes, transfer hoses, or sample bottles can absorb some organic
contaminants or bleed contaminated elements, affecting samples.
To avoid problems, metal or plastic materials should be soaked and washed before use in boreholes
and glues should not be used to join well casings. In constructing sampling wells for trace
concentrations of some oils, glass or Teflon* materials may be needed in well casings or sampling
apparatus.
Sample devices vary with the number of samples per well and with well depth. In the past, obtaining
multiple samples at various depths has required sampling in different wells. Recently, a single well
with a multiple sampler has been used to obtain the same results.
Shallow aquifer sampling (less than 30 feet from the surface) will allow the use of vacuum pumps
to transport samples out of wells. However, deep aquifers (greater than 30 feet from the surface)
will necessitate submerged pumps or air-lift systems. The air-lift system is a pressurized, inert gas
system with chambers and check valves to force samples to the surface. The advantage of an air-lift
system is that samples are not oxidized because they do not come into contact with any oxygen in
the air. Several air-lift systems can be used within a single well if separated by seals. This system
becomes increasingly costeffective with increasing depths. The major problem with the air-lift
system is that the check valves used in sample transfer can become clogged with soil particles if
samples are not screened properly.
For deep wells, changes in pressure can cause chemical changes, such as precipitation in the sample.
With the additional data from samples, accumulation of oil and direction of flow can be confirmed
and recovery devices can be placed for the most cost-effective program.
PRODUCT RECOVERY
Some of the oil on groundwater can be removed three ways:
1. Open trenches
2. Back-filled trenches with recovery crocks
3. Extraction wells.
Water table depth and embankment slumping are the primary factors in selecting a recovery device.
When water table depth is less than 9 feet from the surface, trenching can be an economical method
in oil removal. The depth of the trench should be about 3 feet below the groundwater level and the
width no more than 6 feet. Where possible, the trench should span the entire downgradient edge of
the oil plume (FIGURE 28).
5/93 38
-------
RECOVERY PROCESSES
Oil skimmers or vacuum lines can be lowered into the trench to recover oil, and a groundwater
depression pump can be used to increase the rate of oil and water flow to the trench. If the trench
cannot be extended along the length of the oil plume, an impermeable barrier can be installed to
divert liquid flow toward the trench. For example, bentonite clay slurry can be pumped into narrow
slots in the ground or sheet pilings can be inserted or driven into the groundwater or aquifer base.
VO
PLUME
BOUNDARY
TRENCH
FIGURE 28
AERIAL VIEW OF TRENCHES
When open trenches cannot be maintained because they rapidly fill with mud, or if freezing weather
would freeze water in/an open trench, a recovery crock can be used. A recovery crock consists of
a pipe that reaches from the surface to about 6 feet below the water table. Some pipes can be up
to 6 feet in diameter. The pipe is perforated with 2.5-inch slots or holes to allow oil and water to
enter. After a hole is dug larger than the diameter of the pipe, peagravel is placed in the bottom of
the hole to decrease turbidity by limiting soil particle movement as water levels change. Next, the
crock (pipe) is lowered into the trench so that the end stands on the gravel bed. Before the trench
is filled in with a porous material (e.g., gravel or sand), a plastic lining or other impermeable barrier
is used to line the downgradient side of the trench above and especially below the water table to
guide oil to the crock and halt oil plume migration (FIGURE 29). A variation of this system is to
have radiating, interconnecting, perforated pipe at the water table to guide the product to the crock.
5/93 39
-------
RECOVERY PROCESSES
Ditch
IB
Top View
Sump
IB
To The Separator
-v- v-'- 7-' •-• P;
ir-.'V. ."•"•:::•;-""-rax:
Longitudinal
Section
Depreued W«ierublc
Undisturbed
Wireruble
Cross- Section
FIGURE 29
RECOVERY DITCH WITH SUMP
Product in crocks can be removed with skimmers or vacuum devices. In addition, a groundwater
depression pump can be used to create a cone of depression to encourage liquid flow toward the
crock and increase oil recovery rates (FIGURE 30).
For deeper water tables, augers, water jets, driven well points, and rotary rigs can be used to dig
a recovery well (TABLE 3). Wells should be dug deep enough below the water table to allow for
any groundwater depression techniques used. Auger types vary. Hand-held power augers with 6-
inch outside diameters can drill to 8 feet. Truck-mounted augers with 2-inch outside diameters can
drill to 120 feet. Hollow-stem augers may be used to take undisturbed soil samples. Rotary rigs
can be used for sampling soil when drilling and for sampling water upon completion of the
observation well. Depths of 1,500 feet can be drilled.
5/93
40
-------
RECOVERY PROCESSES
Feed V
Trenches
-------
I/I
^
Ul
Drill Type
1. Rotary
2. Stem auger
3. Hollow-
stem auger
4. Kdley
auger
5. Bucket
anger
Normal
Diameter Hole
4" -20'
4" -8'
4" -8"
8' - 48"
\2' - 11'
TABLE 3
BASIC WELL-DRILLING METHODS
Maximum
Depth
Unlimited
30 -50 ft.
30 -50 ft.
90ft.
90ft.
Average
Time per Hole
Fast
Fast under suitable
soil conditions
Fast under suitable
soil conditions
Fast
Fast
Normal
Expense
Expensive
Inexpensive to
moderate
Inexpensive to
moderate
Moderate to
expensive
Moderate to
expensive
Advantages
1. Good for deep holes
2. Can be used in soils
and relatively soft
rock
3. Widely available
4. Control caving
1. Widely available
2. Very mobile
3. Can obtain dry soil
samples while drilling
1. Good for sandy soil
2. Can set casing through
hollow stem
3. Very mobile
4. Can obtain dry soil
samples and split
spoon samples
5. Controls caving
1. Can install large-
diameter recovery
wells
2. Drills holes with
minimum soil wall
disturbance or
contamination
3. Can obtain good soil
samples
1 . Can obtain good soil
samples
2. Can install large-
diameter recovery
wells
Disadvantages
I. Need to use drilling
fluid
2. Potential borehole
damage with drilling
fluid
3. Requires drilling water
supply
1 . Difficult to set casing in
unsuitable soils (caving)
2. Cannot penetrate large
stones, boulders, or
bedrock
1. Casing diameter
normally limited to 2*
3" o.d.
2. Cannot penetrate large
rock, boulders, or
bedrock
3. Limited availability
4. Normally cannot be
used for recovery wells
1 . Large equipment
2. Seldom available in
rural areas
3. May require casing
while drilling
1. Hard to control caving
2. At times must use
drilling fluid
3. Normally very large
operating area required
-------
vo
TABLE 3
BASIC WELL-DRILLING METHODS
Drill Type
6. Cable tools
7. Air hammer
8. Casing
driving
9. Dug wells
Normal
Diameter Hole
4" - 16-
4" - 12-
2" - 24"
Unlimited
Maximum
Depth
Unlimited
Unlimited
60ft.
10 - 20 ft.
Average
Time per Hole
Slow
Fast
Slow to moderate
Fast
Normal
Expense
Inexpensive to
Expensive
Expensive
Inexpensive
Inexpensive
Advantages
1. Widely available
2. Can be used in soil or
rock
1 . Fast penetration in
consolidated rock
1. Very portable
2. Readily available
1. Readily available
2. Very large diameter
hole easily obtained
Disadvantages
1. Slower than other
methods
2. Hole often cracks
3. May require casing
while drilliong
1. Inefficient in
unconsolidated soils
2. Very noisy
3. Control of dust/air
release
4. Excessive water inflow
will limit use
1 . Limited to uncon-
solidated soil - cannot
penetrate large rocks,
boulders, or bedrock.
2. Difficult to obtain soil
samples
3. Generally inefficient
method to install
recovery well
1. Caving can be severe
problem
2. Limited depth
3. Greater explosive
hazard during
excavating into
hydrocarbons
8
o
8
c/j
£
V)
-------
RECOVERY PROCESSES
Basically, wells can be classified into three types:
1. Single pump well
2. Double pump well
3. Double shaft well.
Single pump wells use one device, such as a skimmer or vacuum device to remove oil and
contaminated water (FIGURE 31). The major problems with single pump wells are (1) large
volumes of oil and water require large capacity storage, (2) separators are needed to treat oil/water
mixtures, (3) some pumps emulsify water with oil, and (4) the pump must be able to handle air,
liquid, and debris. The advantages for the single pump well are that they can be less expensive to
install and operate than other recovery wells (especially when needed for a short time) and they are
effective when low oil/water recovery rates are expected.
FIGURE 31
SINGLE PUMP RECOVERY SYSTEM
5/93
44
-------
RECOVERY PROCESSES
The double pump well combines a product recovery device and a groundwater depression device into
a single well (FIGURE 32). The double shaft well is similar to the double pump well except the
oil recovery device and the groundwater depressing devices are in separate well casings (FIGURE
33). The separation of devices allows better regulation of water level and flow within the well. The
main advantages of double pump and double shaft wells are (1) they are cost-effective for large spill
volumes, (2) they can recover relatively pure products, and (3) they can be made fully automatic.
TO PRODUCT STORAGE
TO SEWER, DRAINAGE, ETC.
:POWER CABLES
SOLID CASING
SLOTTED CASING
(WELL SCREEN)
-4vy?;PRODUCT RECOVERY PUMP
^$?3K&123:S«3S?j&**:FJL* '^
R GRAVEL BACKFILL
FIGURE 32
DOUBLE PUMP RECOVERY WELL
5/93
45
-------
RECOVERY PROCESSES
— TO COLLECTION TANK TO DRAIN-
PERFORATE
"OUTER SHAFT
, j
STATIC LEVELM~1
INNER SHAFT
^iȣEO
* CONE OF
DEPRESSION
r-Jrv**
*».:».-.*:-AT^-'
'^••T/ .st;'.-fi»'/-.l
FIGURE 33
DOUBLE SHAFT WALL
When the groundwater depression device creates a cone of depression, care must be taken to avoid
pumping the well dry or severely lowering the water level around any one well. Past problems with
this technique include oil displacing water in the soil and causing additional contamination and
surface subsidence by collapse of geologic structures.
When using groundwater depression pumps, provisions must be made to handle large volumes of
water pumped from a well. Oil water separation should be used before water is either transported
to a waste handling facility or discharged onto the land. In some cases water can be reinjected into
the ground to increase the recovery rate by flushing oil to the recovery point. In other cases, water
can be added to the surface at the spill location to flush oil through the soil and to increase recovery
rates. The nonresidual oil droplets and soluble oils will be moved. It is most effective with light
products such as gasoline, diesel, and kerosene. In applying large volumes of water to the spill site,
5/93
46
-------
RECOVERY PROCESSES
the cone of depression must be maintained to keep flowing oil within the recovery area. If
government regulations require purification before discharging water in or on the ground, several
methods are available for treatment.
Reverse osmosis uses high pressure to force a solvent (i.e., water) through a membrane but not the
solute (i.e., oil). It is used primarily for removing dissolved organic chemicals. Ultrafiltration is
similar to reverse osmosis but can remove larger organic molecules. Aeration with the use of air,
ozone, or hydrogen peroxide oxidizes dissolved hydrocarbons. Biological treatment uses bacteria
to break down organic molecules on specially prepared carbon particles. Some other techniques such
as ion exchange and chemical treatment are usually not as effective as the previously mentioned
techniques. Where high-quality water is required, a combination of techniques can be devised, such
as oil-water separation followed by aeration and activated carbon filtration.
SAFETY
When flammable materials are being recovered, fire prevention must be considered. Submersible
pumps must be explosion proof and sure pumps, engines, and other igniting sources must be at least
5 feet from recovery wells. Electric underground cables should always be protected.
SUMMARY
Oil on groundwater can be a serious problem. The oil can contaminate water used for drinking,
irrigation or industrial processes. Characteristics such as oil volume, oil viscosity, area of land that
is contaminated, depth to water table, and soil permeability will influence the amount of oil reaching
the groundwater. The hydrogeologic factors within the aquifer will influence oil migration on the
groundwater. Therefore, groundwater monitoring is necessary to have effective location and
recovery of product.
Monitoring should include thorough preliminary investigation and field investigation. Field
investigations require sampling that does not contaminate soil and groundwater samples. Sampling
devices vary from sample probes to complicated well borings with intricate sample casings and
sample pumps. Also, complications can arise in sampling because of highly fissured bedrock,
solution channels in limestone, and irregularities in bedding planes.
Products can be recovered using open trenches, filled trenches with recovery cracks, or extraction
wells. A properly constructed well can recover oil from a large area surrounding the well. Care
must be taken in pumping large quantities of water from an aquifer. Water that is recovered may
be required to be treated before discharge. Well types used are simple pump, double pump,and
double shaft wells. Well choice will depend on the situation.
Safety precautions must be taken when dealing with volatile products.
5/93 47
-------
Section 6
-------
VOLATILIZATION
STUDENT PERFORMANCE OBJECTIVES:
At the conclusion of this section, participants will be able to:
Briefly describe the advantages and disadvantages of volatilization
List at least four factors that influence the operation of a packed tower air
stripping unit
Briefly describe the operation of a packed tower air stripping unit
List at least two differences between an air stripping unit and a steam
stripping unit
Briefly describe a typical soil vapor extraction unit.
5/93
-------
NOTES
AIR STRIPPING
• Physical separation
• Applicable to volatile wastes
• Well established technology
AIR STRIPPING
ADVANTAGES
• High removal efficiency
• Applicable over a large range
• Simple design
• Low cost
AIR STRIPPING
DISADVANTAGES
• Non-destructive
• Non-volatiles
• Vapor treatment
5/93
Volatilization
page 1
-------
NOTES
FACTORS INFLUENCING
AIR STRIPPING OF WASTES
• Waste component's Henry's constant
>0.003 atm-m3/mole concentration
• Surface area
• Air exchange
• Temperature
FACTORS INFLUENCING
AIR STRIPPING OF WASTES
• Contaminants
Suspended solids
Grease and oils
Biological growth
Minerals
Alr-
ConUmlntttd
Ground
Water_
Discharge
DrHuwr Gr1
-------
NOTES
Air Stripper
Contaminated Water
Influent
Effluent to Discharge
or Further Treatment
Discharge to Air
Air Stripping
Column
DESIGN DETAILS
• Distribution system
• Redistribution rings
• Packing support
• Water seal
• Mist eliminator
Influent
A
Contaminated
Ground Water
lent J~\
Mist Eliminator
•Filter Media
^-Redistribution Rings
Stainless
Steel Screen
ir Inlet
Water
Level'
Discharge^
Packed Column Air Stripping System
5/93
Volatilization
page 3
-------
NOTES
AIR POLLUTION CONTROLS
• Carbon adsorption
• Thermal destruction
• Catalytic thermal destruction
DESIGN CONSIDERATIONS
PACKED TOWERS
• Flow rate - tower diameter
• Removal efficiency - tower height
• Surface area - packing material
• Compound - air-to-water ratio
CONSTRUCTION MATERIALS
• Aluminum
• Fiberglass reinforced plastic
• Steel
• Stainless steel
Volatilization
page 4
5/93
-------
AIR STRIPPING COST
$0.05-0.20/1000 Gallons
Contaminated Water
Influent
Discharge to Air
Cooled,
Stripped *i
Effluent to*"
Further
Treatment
Steam Stripper
Condensate to
Incinerator
Air and Steam
SOIL VAPOR EXTRACTION
• Physical separation
• Applicable to volatile wastes
• Proven technology
NOTES
5/93
Volatilization
page 5
-------
/VOTES
Contaminant Flow Toward Well
To Pump
uum Level
Monitor
Extraction Well
Soil Vapor Extraction
Portable
Vacuum
Unit
Vapor/ Quadruple Carbon
Water Adsorption Unit
Separator
Vacuum Extraction Wells
Backup
Carbon
Unit
SOIL VAPOR EXTRACTION
SYSTEM COMPONENTS
• Inlet wells
• Extraction wells
• Air headers/piping
• Flow meters/controllers
• Vacuum pumps/blowers
• Vapor treatment
• Impermeable cap
Volatilization
pages
5/93
-------
NOTES
Volatilization System
Extraction air
bypass valve
Extraction air
Inlet "ow metor
we|| Extraction Extraction air
manHold \^ sampling port
Stone
vertical
•xtractlon
vent pipe
Vapor
Impermeable treatment
cap
Soil contamination
INLET WELLS
• Ground surface
• Passive
• Active
EXTRACTION WELLS
• Vertical > 20 feet
• Horizontal - trenches
• Cluster wells - variable strata
• Spacing-15 to 100 feet
soil bulk density
soil porosity
5/93
Volatilization
page 7
-------
NOTES
AIR HEADERS/PIPING
• Materials
PVC
steel
• Layout
manifold
grid
• Freeze protection
FLOW METERS/CONTROLLERS
• Meters
pilot tube
orifice plate
totalizing
• Control valves
butterfly
. ball
VACUUM PUMPS/BLOWERS
• Industrial blowers
rotary
turbine
• Vacuum pumps
positive displacement
Volatilization
page 8
5/93
-------
/VOTES
VAPOR TREATMENT
• Air/water separator
traps
condenser
• Carbon adsorption
• Thermal destruction
IMPERMEABLE CAP
• Purpose
stop infiltration
direct air movement
• Materials
clay
asphalt
concrete
polyethylene
SOIL VAPOR EXTRACTION COST
$10.00-50.00/Cubic Yard
5/53
Volatilization
page 9
-------
VOLATILIZATION
Air Stripping
General Description
Air stripping is a mass transfer process in which volatile contaminants in water or
soil are transferred to gas. As shown in FIGURE 1, there are four basic equipment
configurations used to air-strip liquids.
PACKED COLUMN
EXIT AIR
DISTRIBUTOR
DIFFUSED AIR BASIN
A|R SUPPLY
EFFLUENT!
MATERIAL
SUPPORT
^•PLATE
;—INCOMING
AIR
-EFFLUENT
COKE TRAY AERATOR
DISTRIBUTING
TOWER
WATER
INLET
OUTLET
WATER
OUTLET
INLET
COLLECTION
BASIN
FIGURE 1
AIR STRIPPING EQUIPMENT CONFIGURATIONS
5/93
11
-------
VOLATILIZATION
Air stripping is frequently accomplished in a packed tower equipped with an air
blower. The packed tower works on the principle of countercurrent flow. The water
stream flows down through the packing, while the air flows upward and is exhausted
through the top. Volatile, soluble components have an affinity for the gas phase and
tend to leave the aqueous stream for the gas phase.
In the cross-flow tower, water flows down through the packing as in the
countercurrent packed column; however, the air is pulled across the water flow path
by a fan. The coke tray aerator is a simple, low-maintenance process requiring no
blower. The water being treated is allowed to trickle through several layers of trays.
This produces a large surface area for gas transfer. Diffused aeration stripping and
induced draft stripping use aeration basins similar to standard wastewater treatment
aeration basins. Water flows through the basin from top to bottom or from one side
to another with the air dispersed through diffusers at the bottom of the basin. The
air-to-water ratio is significantly lower than in either the packed column or the cross-
flow tower (Canter and Knox, 1985).
Applications/Limitations
Air stripping is used to remove volatile organics from aqueous wastestreams.
Generally, components with Henry's Law constants of greater than 0.003 can be
effectively removed by air stripping (Conway and Ross, 1980). This includes such
components as 1,1,1-trichloroethane, trichloroethylene, chlorobenzene, vinyl
chloride, and dichloroethylene.
The feed stream must be low in suspended solids and may require pH adjustment of
hydrogen sulfide, phenol, ammonia, and other organic acids or bases to reduce
solubility and improve transfer to the gas phase. Stripping is often only partially
effective and must be followed by another process such as biological treatment or
carbon adsorption.
Combined use of air stripping and activated carbon can be an effective way of
removing contaminants from groundwater. The air stripper removes the more
volatile compounds not removed by activated carbon and reduces the organic load on
the carbon, thus reducing the frequency (and expense) of carbon regeneration.
The countercurrent packed tower has been the most widely used equipment
configuration for air stripping at hazardous waste sites. The reasons for this are
(Canter and Knox, 1985):
(1) It provides the most liquid interfacial area
(2) High air-to-water volume ratios are possible because of low air
pressure drop through the tower
5/93 12
-------
VOLATILIZATION
(3) Emission of stripped organics to the atmosphere may be
environmentally unacceptable; however, a countercurrent
tower is relatively small and can be readily connected to
vapor recovery equipment.
The major disadvantage of the packed column is the high energy cost.
Design Considerations
The design of a packed tower air stripper generally involves determining the cross-
sectional area of the column and the height of the column packing. The cross-
sectional area of the column is determined from physical properties of the air flowing
through the column, the characteristics of the packing, and the air-to-water flow ratio.
A key factor is the establishment of an acceptable air velocity. A general rule of
thumb used for establishing the air velocity is that an acceptable air velocity is 60
percent of the air velocity at flooding. Flooding is the condition in which the air
velocity is so high that it holds up the water in the column to the point where the
water becomes the continuous phase rather than the air. If the air-to-water ratio is
held constant, the air velocity determines the flooding condition. For a selected air-
to-water ratio, the cross-sectional area is determined by dividing the air flow rate by
the air velocity. The selection of the design air-to-water ratio must be based on
experience or pilot-scale treatability studies. Treatability studies are particularly
important for developing design information for contaminated groundwater (Canter
and Knox, 1985).
The height of column packing may be determined by the foHowing equation (Canter
and Knox, 1985):
In
Z =
(X2 - Y,
(l-A) + A \L
KLaC(l-A)(l-X)M
where:
Z
L
X,
KLa
C
H
height of packing, ft.
water velocity, Ib-mole/hr/ft2
influent concentration of pollutant in groundwater, mole
fraction
effluent concentration of pollution in groundwater, mole
fraction
mass transfer coefficient, gal./hr.
molar density of water = 3.47 Ib-mole/ft3
Henry's Law constant, mole fraction in air per mole fraction
in water
air velocity, Ib-mole/hr/ft2
5/93
13
-------
VOLATILIZATION
A = L/HG
(1-X)M = the average of one minus the equilibrium water concentration
through the column
Y, = influent concentration of pollutant in air, mole fraction
In most cases, the following assumption can be made:
(1) Y, = O, there should be no pollutants in the influent air.
(2) (1-X)M = 1, the influent concentrations should be too small when
converted to mole fraction to shift this term significantly from
1.0.
In
£ -
X2 (1-A) + A
Xi
>•
KLaC(\-A)
The mass transfer coefficient, KLa, is determined from pilot-scale treatability studies
and is a function of type of compound being removed, air-to-water ratio, groundwater
temperature, type of packing, and tower geometry (Canter and Knox, 1985).
Calgon Carbon Corporation maintains a computer modeling system that determines
the appropriate tower diameters, parking heights, air-to-water ratios, and tower
packing for a particular application (Calgon Carbon Corp., 1983). This system
facilitates rapid mobilization of the packed tower equipment to a site.
Technology Selection/Evaluation
In recent years, air stripping has gained increasing use for the effective removal of
volatile organics from aqueous wastestreams. It has been used most cost-effectively
for treatment of low concentrations of volatiles or as a pretreatment step prior to
activated carbon. Calgon manufactures a treatment which combines air stripping and
activated carbon.
The equipment for air stripping is relatively simple, start-up and shut-down can be
accomplished quickly, and the modular design of packed towers makes air stripping
well suited for hazardous waste site applications.
An important factor in the consideration of whether to use air stripping technology
for the removal of volatile contaminants is the air pollution implications of air
stripping. The gas stream generated during treatment may require collection and
subsequent treatment or incineration.
5/93 14
-------
VOLATILIZATION
Costs
Packed tower air strippers have higher removal efficiencies than induced-draft
systems, which are similar to diffused aeration systems. However, the induced-draft
system is lower in capital cost and requires less energy to operate than a packed-
tower system.
TABLE 1 describes the installed cost of an induced-draft stripper manufactured and
marketed by the Calgon Carbon Corporation. As shown in TABLE 1, the installed
cost of an induced-draft stripper capable of treating 700 gpm and removing 75
percent of the TCE contamination is about 31 percent ($19,000 vs. $61,300) of the
cost of a packed-tower capable of removing 95 percent of the TCE. Assuming that
a well pump with a minimum discharge head of 25 psig is required to feed both
units, the packed-tower also uses an additional $5,100 per year in electrical energy
for operation of the blower.
TABLE 1
AIR STRIPPING COST ESTIMATES
(Basis: 700 gpm; 1000 micrograms/Iiter TCE)
Induced-Draft1 Stripper
(75% Removal)
Packed-Tower2 5-ft.
Diameter (95% Removal)
Air Stripping Equipment3
Stripper Assembly & Installation
Equipment Subtotal
Recharge Pump; Assembly &
Controls
Foundation/Sump4
Equipment Freight
Project Management
Project Contingency
Total
$15,000
4.000
$19,000
$42,300
19.000
$61,300
$16,000
18,000
2,000
10,000
7.000
$72,000
$16,000
23,700
5,000
20,000
20.000
$146,000
'Calgon Model No. 909B (8'0" x 9'1" x 9'0").
2Tower is made of fiberglass-reinforced plastic and contains 15 ft. of 1-in. diameter
polypropylene pall ring packing.
3Cbst includes tower, packing, packing support, demister, 4,000 cfm fan with 10 hp motor,
damper, piping valves, and ductwork.
4Sump 5' x 5' x 8' below-grade concrete.
Source: O'Brien and Stenzel, undated
5/93
15
-------
IS\
VO
CONTAMINATED WATER
INFLUENT
I HEAT
EXCHANGER
COOLED STRIPPED
EFFLUENT TO FURTHER
TREATMENT
ORGANIC
VAPORS
INTERNAL WATER
DIRECTION OF FLOW
CONDENSER
DISCHARGE
TO AIR
O
r
H
i—i
r
N
H
O
. CONDENSATE TO
INCINERATOR
INTERNAL STEAM AND
AIR DIRECTION OF FLOW
STRIPPED EFFLUENT
STEAM INPUT
AIR BLOWER
FIGURE 2
STEAM STRIPPER
-------
VOLATILIZATION
In a typical treatment system, repumping of the treated water would be required.
Adding the cost of a sump, flow control, and a pump, the overall project cost for the
induced-draft system would be about one-half the cost of the packed tower system
(Calgon Carbon Corp., undated).
Steam Stripping
Steam stripping is a unit process that uses steam to extract organic contaminants from a liquid
or slurry. Direct injection of live steam or multiple pass heat exchangers are the two most
prominent methods described as steam stripping. Steam stripping by direct injection of steam
can be used to treat aqueous and mixed wastes containing organic contaminants at higher
concentrations and/or having lower volatility than those streams which are air strippable. It
is an energy-intensive process and the steam may account for a major portion of the operating
costs (FIGURE 2).
This process is similar to steam distillation except that reflux of recovered material is usually
not done. It can handle solids in the waste that may foul the heating coils of a distillation
unit. In addition, wastes of more variable composition can be processed. The disadvantages
of this technique include the addition of water to the treated waste and the high energy
requirements.
Waste Type Handled
Steam stripping has been widely used to strip hydrogen sulfide (H2S) and ammonia
(NH3) from refinery wastes. Volatiles, organic compounds, as well as phenols,
ketones and phthalates, can be removed from aqueous wastes, slurries, and solids by
this process. Effective removal of high concentrations (1-20 percent) of organics can
be accomplished. However, concentrations of less than 1 percent can be more
effectively treated by other treatment techniques.
Restrictive Characteristics
Water-miscible organics and metal contaminants are not removed by this process.
Contact between steam and solid materials is more difficult to achieve than in liquid
streams.
Mobile System Considerations
The system can be transported in a horizontal position and hydraulically raised to a
vertical position for onsite treatment. Electric or diesel-powered steam generators
and condensers, as well as collection and storage equipment, are required for this
process. Energy requirements usually limit the size and performance of this process.
Adequate utilities have to be provided for steam stripping. The concentrated bottom
and top streams may require additional treatment.
5/93 17
-------
VOLATILIZATION
Environmental Impacts
Concentrated overhead vapors are condensed into a liquid form and must be treated
further or sent directly to a fume incinerator. The stripped aqueous waste may
require further treatment (e.g., carbon adsorption) if the desired level of removal is
not achieved by steam stripping.
Costs
Costs vary widely depending on the flow rates, heating requirements, and ease of
component separation. The operating costs will be mostly affected by the energy
requirements and labor costs.
Commercial Applications
No mobile steam stripping units have been applied to hazardous waste treatment. A
number of companies have, however, expressed interest in developing a mobile unit.
Several petroleum companies may also be developing mobile systems.
Soil Vapor Extraction
General Description
Soil vapor extraction is known by several names, including soil venting, forced soil
venting, in-situ air stripping, and in-situ volatilization. Regardless of the name it
goes by, the process is generally the same. An extraction well is placed within the
unsaturated zone of a contaminated site. Air is then drawn out of the extraction well
by a vacuum pump or blower. As air passes through the soil, volatile components
diffuse from the soil particles and are carried with the air as it passes out of the well.
A wide range of pilot- and full-scale vapor extraction systems have been constructed
and studied under a variety of conditions. This remediation technology has been
selected for use at 13 percent of the sites which have selected treatments according
to the 1988 Records of Decision (RODs). Additionally, this technology has been
applied to underground storage tank cleanups and RCRA corrective actions.
Applicable Wastes
Contaminants with low solubilities and high vapor pressures (substances with Henry's
Law constant values greater than 0.003 atm-m'/mole) found within the unsaturated
zone may be removed using this technology. However, the efficiency in removing
these contaminants is highly dependent on specific site geology and soil
characteristics. TABLE 2 lists the characteristics that impact process feasibility.
5/93 18
-------
VOLATILIZATION
TABLE 2
TECHNOLOGY SUMMARY
Characteristics
Impacting Process
; Feasibility
Reason for Potential Impact
Data Collection
Requirements
Presence of:
• Less volatile organics
• Metals
• Cyanides
• Inorganics
Only volatile compounds with a Henry's Law
constant of approximately >3 x 10"3 atm-m3
/mole can be effectively removed by vacuum
extraction; theoretically, steam or hot air
extraction should apply to less volatile
compounds.
Analysis for priority
pollutants; Henry's
Law constant or
vapor pressures for
organics.
High solubility of volatile
organics in water
Dissolved organics are more mobile and harder
to remove from aqueous phase.
Contaminant
solubilities.
Unfavorable soil
characteristics:
• Low permeability
• Variable soil
conditions
• High humic content
High moisture content
Hinders movement of air through soil matrix.
Inconsistent removal rates.
Inhibition of volatilization.
Hinders movement of air through soil.
Percolation test; pilot
vapor extraction tests.
Soil mapping.
Analysis for organic
matter.
Analysis of soil
moisture content.
Soil vapor extraction techniques may also be used as a pretreatment to remove
volatile contaminants from the vadose zone prior to the use of other technologies.
Process Description
Soil vapor extraction is a physical process; therefore, no destruction of the waste
components occurs without the addition of specific equipment items designed for that
purpose. It is a process that is limited by the ability of a contaminant to desorb from
a soil particle and diffuse into air. Soil vapor extraction is becoming a widely used
technology because of the following benefits:
• No extensive site excavation
• Relatively simple installation
• Applicable to numerous volatile contaminants
5/93
19
-------
VOLATILIZATION
• May be used to clean under existing structures
• Flexible design
• Relatively, low cost.
Many variations of soil vapor extraction systems have been used effectively at
numerous sites. FIGURE 3 shows common system components:
• Extraction wells
• Inlet wells
• Air headers/piping
• Vacuum pumps/blowers
• Flow meters/controllers
• Vapor treatment
• Impermeable cap.
Extraction wells should be designed to penetrate the unsaturated zone to the capillary
fringe. Vertical wells are installed when this depth is greater than 20 feet. When
groundwater is at a shallow depth or if the contamination is confined to near-surface
soils, then extraction wells may be placed horizontally in trenches. If the stratigraphy
of the soil presents significant variations in permeability, cluster wells may be used
to selectively treat individual strata. This is done by screening the wells so that the
screened section of an individual well within the cluster is set within a specific area.
Vacuum applied to each well head can be varied to improve air movement through
a given strata.
Well spacing is determined by the soil's bulk density and its porosity. In general, the
lower the bulk density and the higher the porosity of the soil, the farther apart
extraction wells may be placed. In practice the distance between wells is usually
determined by pilot testing and ranges from 15 feet for soils with high bulk densities
and low porosities to 100 feet for soils with low bulk densities and high porosities.
5/93 20
-------
VOLATILIZATION
Extraction
Well
Control
V«l»t
Air/Water
Separator
Inlet
Well
**/«»" Blower
n I =
Vapor
Treatment
i «
Ml
u
Cap
Contaminated
Soil
3§jr Groundwater
Table
FIGURE 3
SOIL VAPOR EXTRACTION SYSTEM
Proper installation of the extraction wells is one of the keys to ensuring proper
operation of the system (FIGURE 4). A 10 inch or larger diameter hole is drilled
into the areas that are documented as having the highest level of contamination. The
hole must only penetrate down to the capillary fringe to ensure that only minimal
amounts of water are withdrawn during process operations. The well is normally
screened the full length of the installed depth, except for the upper 5 feet (this may
vary depending on site stratigraphy). A grout plug may be placed at the bottom of
the well hole to serve as an anchor and positive seal for the well screen. A 4- or 6-
inch diameter PVC well is then installed plum with coarse sand packing surrounding
the screened length of the casing. If no grout plug has been provided, the foot of the
screened casing should be capped. Bentonite is packed around the upper section of
the casing to within 2 feet of the surface. A grout plug extending several inches
above the surface and down to the bentonite finishes the installation. The grout seal
ensures that there will be no air leakage from around the well head during system
operation.
5/93
21
-------
VOLATILIZATION
Riser
2' to 4' PVC Casino
10' Auper Hole
Concrete Cap
mmma^m Ground Surface
Cemenl-Bentonlte Grout
Bentonite Pellets
Course Sand
Centralirer (optional)
PVC Cap
FIGURE 4
TYPICAL EXTRACTION/AIR INLET WELL CONSTRUCTION
Variations on extraction well installations are common. However, the sealing of well
heads is essential to minimize loss of vacuum.
Inlet wells are constructed similarly to extraction wells and provide necessary air
supply to the system. Air inlets may include:
• Ground surface
5/93
22
-------
VOLATILIZATION
• Passive wells
• Active wells.
The ground surface provides the greatest amount of surface area exposed to the
atmosphere. Therefore, when an extraction well is under vacuum, air will be drawn
from the ground surface immediately adjacent to the well (FIGURE 5). The zone
of influence will vary relative to soil characteristics and the capacity of the vacuum
pump or blower. Regardless, the zone of influence diminishes as distance from the
extraction well increases.
Passive wells may be installed to provide direct venting within specific subsurface
strata. These wells are constructed similarly to extraction wells; however, well
screening will be limited to accommodate a specific strata. They remain open to the
atmosphere, thereby providing an air inlet source. Normally inlet wells are installed
in a circular pattern surrounding the extraction wells. These wells may also be used
as extraction wells if redirection of the air flow through the subsurface is desired.
FIGURES
AIR FLOW PATTERNS IN VICINITY OF A SINGLE EXTRACTION
WELL (NO CAP)
5/93
23
-------
VOLATILIZATION
Active wells force air into the subsurface. These wells are essentially passive inlet
wells that have been fitted with an air blower (FIGURE 6). Injected air, along with
vacuum, should provide a push-pull effect. However, it is difficult to balance air
flows in soils. This means that active inlet wells often serve as a means to diffuse
volatiles from soils immediately adjacent to the well screen and distribute them within
other soil strata.
These wells may also be installed into contaminated aquifers. Air injected into the
aquifer tends to strip volatiles from contaminated groundwater, forcing them up into
the capillary fringe and the unsaturated zone. Once the volatiles are in the
unsaturated zone, they will migrate to the extraction wells.
FIGURE 6
AIR FLOW FROM INJECTION WELLS
5/93
24
-------
VOLATILIZATION
Once the extraction wells have been installed, they are connected by a piping system.
The pipe that is normally used is Schedule 40 PVC; however, fiberglass-reinforced
plastic and steel pipe have been used. Piping is laid out to connect the vacuum
system to the extraction wells in a manifold or grid network. These types of layouts
minimize friction loss through the pipe and maximize system flexibility.
Piping may also be installed underground when systems must be installed across
active roadways or walk areas. This may also provide freeze protection for the pipes.
Such protection is warranted for soil vapor extraction systems installed in northern
climates because moisture collecting in the piping network could freeze and crack the
pipes.
The vacuum for extracting soil air is developed by typical vacuum pumps or
blowers. Positive displacement vacuum pumps will usually provide high vacuum but
low total air flow. For example, at one site, a vacuum pump was installed that
moved 18 cfm of air at vacuums ranging from 25 to 30 inches of mercury.
Alternately, at a site where an industrial blower was used, up to 3000 cfm of air was
moved at vacuums up to 9 inches of mercury. Therefore, blowers such as those of
rotary or turbine design will provide high volumes of air movement at lower vacuum.
Electric motor drives for these systems are low (10 horsepower or less). Pressure
from the outlet side of the pumps or blowers is often used to drive the exit gas
through a treatment system. Such treated air may be piped into the system's inlet
wells.
Knowledge of gas flow rates and total volume is essential to determine the mass of
contaminants removed from the soil. Gas flow meters should be installed on a
straight pipe run between an extraction well and the vacuum source. This location
minimizes turbulent flow conditions that could influence the accuracy of the meter
and is representative of the vapors that are being extracted. However, because this
location remains under vacuum during operation, any meter installation must remain
airtight to minimize leakage. Meters that are used include pilot tubes, orifice plates
with manometers, or totalizing designs. Flow measurements from individual wells
are useful for optimizing the system. For example, if a zone of contamination lies
close to one extraction well, it may be beneficial to concentrate vacuum on that well
to encourage rapid movement of the contaminant. This may be accomplished by
installing control valves in the piping system. Installation of a control valve at the
head of each extraction well can maximize operational flexibility of the system. The
valves that are used should minimize moisture retention within the piping. Both
butterfly valves and ball valves have been used successfully in this application.
Subsurface conditions vary considerably from one site to another. Soil moisture
content is one parameter that can affect operating efficiency of the system. When a
vacuum is drawn on soils, water associated with the soil will volatilize. As water
vapor exits the well, it condenses on the inside of the piping network and will enter
the vacuum pump. Eventually, moisture buildup will result in greater maintenance
5/93 25
-------
VOLATILIZATION
requirements for the system. To minimize such effects and to provide protection for
the vacuum pump, an air/water separator should be installed between the extraction
well and the vacuum source. These separators are often fabricated from standard
materials such as 55-gallon drums. The drum is baffled so that the influent vapor
entering near the top of the drum impinges on it and is driven downward. Vapor
exits the separator through an opening on the opposite side of the drum. The baffle
extends to only about three-fourths of the depth of the drum. At the base of the drum
is a valved opening for release of the fluids that collect during operation. To enhance
condensation, stainless steel mesh may be packed in the base of the unit.
The highest concentration of volatile organic chemicals (VOCs) will be extracted from
the soil when the system is started up and equilibrium is reached. Because the system
itself is a physical means of separation, there is no destruction of the VOCs that are
removed from the soil. Direct discharge of VOCs to the atmosphere may be
restricted by state or local regulatory agencies. If VOCs are released to the
atmosphere provisions must be made to control the emissions. Control is
accomplished by one or more of the following:
• Mass flow rate control
• Vapor phase carbon adsorption
• Exhaust gas combustion.
Mass flow rate control is simply limiting vapor extraction flow rates so that the total
mass of VOCs discharged is below permit limits. This is the least expensive option
but results in extending the time required to clean up the site and provides no
destruction of the VOCs.
Vapor phase carbon adsorption is used most frequently on small systems. In
practice, two or more canisters of carbon are placed in series either at the inlet or
outlet of the vacuum source. The efficiency of the system may be increased. Carbon
adsorption is also a nondestructive technology. Therefore, the carbon itself must be
disposed of in an approved landfill, incinerated, or regenerated by means of a thermal
desorption.
Exhaust gas combustion is the most expensive option, but results in destruction of
the VOCs. Combustion may be accomplished in a number of different ways.
However, in all cases, the goal is to heat the VOCs to about 2000°F. Because the
vapors that are extracted normally contain low concentrations of VOCs with respect
to concentrations of oxygen, high-temperature combustion will oxidize the VOCs to
carbon dioxide, water vapor, and trace by-products. Catalytic vapors are heated in
a combustion chamber to temperatures only about half that of incinerators. The
heated vapors are then passed through a catalyst chamber. In the chamber, the rate
of the oxidation reactions is increased, which results in combustion of VOCs at lower
temperatures.
5/93 26
-------
VOLATILIZATION
Moisture within the soil around the vapor extraction area affects system operations
in several ways. Moisture may solubilize some volatile substances. This may
increase the mobility of the substance within the subsurface and carry the substance
to greater depths with additional infiltration. Soil moisture also can fill voids between
soil particles, thereby limiting the amount of exposed particle surface area as air is
drawn past. Therefore, limiting the amount of moisture in the subsurface can
maximize performance of soil vapor extraction systems. This is normally done by
capping the area that is to be controlled with an impermeable cap of clay, asphalt,
concrete, or polyethylene.
Polyethylene is usually the least expensive option. However, if it is used, drainage
must be provided to prevent water from pooling on the surface. Capping the site may
also be used to direct air infiltration. Because the soil surface is the main source of
inlet air to the system, limiting air infiltration via an air cap will result in greater air
volumes being drawn from outside the capped area.
Monitoring
The highest recovery rates of VOCs for any given system are normally found during
the initial start-up. Therefore, exhaust gas controls are most important at this point
in the operation. As the clean-up progresses, concentrations of VOCs in the exhaust
gas decrease. The rate of diffusion limits the recovery of VOCs. Several methods
are used to determine how well a clean-up is progressing. These include:
• Exhaust gas monitoring
• Soil borings
• Onsite soil gas analysis.
Exhaust gas monitoring is normally done by analyzing gas samples collected from
the extraction wells. The concentration of VOCs multiplied by the flow rate yields
the total mass of VOCs extracted per unit time. It is important to adjust the flow to
standard units (usually dry standard cubic feet per minute [dscfm]) to ensure that the
calculations of mass values are accurate. Eventually, analysis of gas samples may
show that VOCs are no longer present in the exhaust gas. This means that for the
zone of influence swept by the system, the rate of diffusion of VOCs is sufficiently
low so that none are detectable.
If the vacuum is shut off and left off for a period of time, the VOCs in the soil may
continue to diffuse into the surrounding air space. If the vacuum is restarted, analysis
of the exhaust gas will reveal measurable VOC concentrations. Therefore, weekly
monitoring of exhaust gases for VOCs can indicate that the clean-up is progressing.
When no VOCs are detected, the vacuum should then be restarted, and the exhaust
gas should be analyzed. If no VOCs are detected (or the concentration of VOCs is
within acceptable levels), then the vacuum should be shut down for a period of about
5/93 27
-------
VOLATILIZATION
1 month. Exhaust gas analysis should then be resumed to determine whether further
operation of the system is warranted.
Soil borings can be used to indicate when residual VOCs remain in the treated area.
They can also be used to indicate where a treatment zone ends. Borings should be
used to identify VOC contamination within the area to be treated. The contaminant
map that is generated may then be compared directly to similar samples taken after
obtaining negative exhaust gas analyses as discussed above. Obtaining samples from
soil borings on a routine basis is not recommended because exhaust gas monitoring
will be a better indicator of system operation.
Onsite soil gas analysis involves the use of colorimetric tubes to determine
qualitatively whether specific contaminants remain within the soil. These field tests
are relatively inexpensive and can give a quick indication of whether specific areas
have been swept by the system. The analysis makes use of colorimetric detector tube
and pump systems to which a tygon or silicon sample tube has been attached.
The site of interest is located and a hand tool is used to bore out a hole of about 1
inch in diameter to the depth of interest. Results are read directly from the tube
according to manufacturer's directions. Such tests may be used to provide
information to determine whether extraction wells should be removed from service
or whether additional vacuum may be required in a given area.
Costs
Soil vapor extraction systems should be pilot tested before numerous extraction wells
are set at any site. Piloting these systems involves the installation of one or more
extraction wells, pipe and fittings, valves, orifice plate and manometer, blower with
motor, and a carbon adsorption unit.
Capitol costs:
Schedule 40 PVC pipe, 6 inch, slotted $25/ft
Schedule 40 PVC pipe, 6 inch 20/ft
PVC fittings 100/each
Blower with motor (varies with capacity) 300-3,000
Orifice plate and manometer 500
Carbon adsorption canister 800
5/93 28
-------
VOLATILIZATION
Installation costs:
Well installation 60/ft
Pipe fitting 20/ft
Concrete base for blower and carbon 300-500
Electrical 5-10/ft
Operation and maintenance costs:
Regenerate/replace carbon 400/each
Blower/pump operation
Calculate using the following formula:
$/year = fan brake hp x 0.746 kw/hp x 8,760
hrs/yr x $/kw-hr
Maintenance 4% installed cost
5/93 29
-------
Section 7
-------
INORGANIC TREATMENT
STUDENT PERFORMANCE OBJECTIVES:
At the conclusion of this section, participants will be able to:
• List three types of inorganic wastes
• List at least two waste characteristics that affect inorganic treatment
• Briefly describe the following types of inorganic treatment technologies:
Neutralization
Precipitation
Cyanide destruction
Oxidation and reduction
Ion-resin exchange.
5/93
-------
NOTES
HAZARDOUS
INORGANIC WASTE
• Corrosives
• Metals
• Cyanides
CORROSIVES
• Characteristics
D002 characteristic waste
pH
Steel corrosion
K062 listed waste for spent
pickle liquors
METALS
HSWAOF1984
• Landfill ban priority metals
Ni, Tl, Cr(VI)
"Subtitle C" - Sec. 3001 & 3004
D002 • characteristic waste
• RCRA wastes
F006 - electroplating operations
K002 to K008 - inorganic pigments
K061 & K069 - emission control dust
D004 to D011-TCLP metals
5/93
Inorganic Treatment
page 1
-------
NOTES
CYANIDES
F007toF009
Electroplating solutions
F010toF012
Metal heat-treating solutions
K011toK013
Acrylonitrile production
TYPICAL INORGANIC WASTES
• Hydrochloric acid etching solution
pH1.5
• Copper plating waste
25,000 mg/L Cu* *
pH 6.0, 500 mg/L NaCN
• Chromium rinse water
pH 7.0,15,000 mg/L Cr(VI)
WASTE CHARACTERISTICS
AFFECTING TREATABILITY
• Physical form
• Concentration
• Solids content
• Other contaminants
Organics
Metals
Chelating agents
Inorganic Treatment
page 2
5/93
-------
/VOTES
TREATMENT PROCESSES
• Neutralization
• Precipitation
• Cyanide destruction
• Oxidation & reduction
• Ion exchange
NEUTRALIZATION
• Concentration
Exothermic reactions
• Solids & sludges
• Corrosion-resistant equipment
• Creating water, H+, OH"
CHEMICAL PRECIPITATION
• Solubility
• Metal hydroxide sludges
• Optimum pH
• Treat effluent
5/55
Inorganic Treatment
page 3
-------
NOTES
CHELATE - (che
ion in which a m
bond from the or
e, "crab's claw") a compound or
3tal ion is held by more than one
iginal molecule.
Chemical
Precipltants
^S]~
Liquid
Feed 1
01
Precip
Tank
Flocculants/
Settling Aids
"O 4 — 1 Flocculation
£d^ Well — >
n \ r-r-
V \ ff
f" fc 1 "* k
/ lo--f
U3b
tator ^ ^
Flocculating
Paddles
fc*t c«,..-,
7^, I"1"0"1
IL-. Baffle
_k. Qliirlna
Flocculator-
Clarifier
CYANIDE DESTRUCTION BY
ALKALINE CHLORINATION
• pH sensitive
• Non-selective
Chlorinated organics
• Metal hydroxide sludges
• Treat effluent
Elevated pH
Chlorinated organics
Inorganic Treatment
page 4
5/93
-------
NOTES
ALKALINE CHLORINATION
CHEMICAL PROCESS
1) Cl, + NaCN —> CNCU NaCI
chlorine cyanide cyanogen sodium
chloride chloride
2) CNCI + 2NaOH —t NaCNO
cyanogen caustic
chloride soda
sodium
cyanate
water sodium
chloride
Sample Chemical Oxidation •
Alkaline Chlorination (Destruction of Cyanide)
Carbon
Column
Heat
Covered, Jacketed Reactors
1st Stage
ZM »t>J« Efficiency)
CHEMICAL REDUCTION BY
REDUCTION / OXIDATION
• Reducer & oxidizer
• Soluble metals non-toxic
• Cr(VI), Pb, Hg
• Metal hydroxide sludges
• Treat effluent
5/93
Inorganic Treatment
page 5
-------
NOTES
Sample Chemical Reduction
Acid Reducing Agent
F««d Feed Lima
H
•
-+G~ Tr~
so,
pH Control /•«, ..,
ChramWkste // Mlxer
Water Fast) r
_xwf r
r^T
1 f*,>' t. ^ri<
| or — ^ ur
Chrome Reduction Tank
Slurry Hopper
Ca
(OH),
^
i[^ /r
--NX— -»'v^'vofXk
%
Cr"+OH>Cr(OHf
^v
/
1 >j
Chrome Precipitation
^Effluent
ydroxlde
ludge
ION EXCHANGE
• Removes low concentrations of soluble
metals
• Recovers concentrated metal streams for
recycling
• Removes cations (+) and anions (-)
• Types of resins
Naturally occurring
Synthetic
ION EXCHANGE
• Limitations
PH
Suspended solids
Other organics
Inorganic Treatment
page 6
5/93
-------
NOTES
Ion Exchange
Acid
Waste Containing Regenerant
Compound MX
-li
Removal
Regeneration
MR+2H '> H, R+M"
Cation
Exchanger
Caustic
Regenerant
u
Anion
Eichingtt
Removal
RX+20H"
Regeneration
Deionized
Effluent
^ Spent
Regenerant
5/33
Inorganic Treatment
page 7
-------
INORGANIC TREATMENT
CHEMICAL TREATMENT TECHNOLOGIES
Chemical Redox Treatment
Reduction-oxidation (redox) reactions involve the chemical transformation of reactants where
the oxidation state of one is raised while the other is lowered. The process will destroy or
reduce the toxicity of many toxic organics and heavy metals. Specific solution pH, rapid
agitation, and chemical addition requirements must be met to ensure a complete chemical
reaction. Oxidizing agents used for chemical oxidation include ozone, hypochlorite,
hydrogen peroxide, chlorine, and potassium permanganate. Reducing agents include ferrous
sulfate, sodium sulfate, sulfur dioxide, iron (+12), aluminum, zinc, and sodium borohydride.
Oxidation-reduction potential (ORP) electrodes are used to monitor the reaction progress.
Redox reactions are applied to a number of different contaminants; either oxidizing agents
or reducing agents are applied to the waste under separate facilities. FIGURE 1 shows a
typical oxidation system.
Waste Type Handled
Reduction-oxidation has most commonly been applied to aqueous wastes with low
organic concentrations (<100 ppm) and heavy metals. However, efforts have
recently focused on applying it to slurries, sludges, and soils. Wastes amendable to
oxidation include benzene, phenols, most organics, cyanide, arsenic, iron, and
manganese. Wastes amendable to reduction include chromium (VI), mercury, lead,
silver, chlorinated organics, and unsaturated hydrocarbons. Applying a water-reagent
mixture to sludges and flushing system may improve performance.
Restrictive Characteristics
Contact between the reagents and the contaminants is crucial for efficient chemical
reaction. Therefore, special precautions need to be exercised when applying the
reagents to solid (soil) materials. Oxidizing agents are strong oxidizers and do not
discriminate between natural organics and contaminants, so excess agents may be
required. Narrow pH ranges need to be controlled for optimum reaction rates. A
wide range of contaminants may complicate the process. For example, if oxidation
of organics is conducted in the presence of chromium (III), the chromium will also
be oxidized to the more toxic and mobile chromium (VI). In-situ soil systems may
be affected by decreased permeability of soils (due to hydroxide precipitation) or loss
of adsorption capacity (due to oxidation/reduction of soil organics).
Mobile System Considerations
Equipment required for aqueous waste treatment is relatively simple. Enclosed
cylindrical tanks with rapid mix agitators are used as the reaction vessel. Controls
5/93 9
-------
INORGANIC TREATMENT
may include pH, ORP, and meter pumps. Storage tanks for reagents and pH
adjustment materials are also required. Slurries and soils may require larger reaction
vessels for longer detention times. In-situ methods would require subsurface injection
of reagents/water.
Lime
SMry
Cr3+ Cr(OH)3
Mixing look
lo Fdlrolioo/
Seaimenloiion
Mixing lonk
FIGURE 1
CHEMICAL REDUCTION OF HEXAVALENT CHROMIUM (Cr6+)
Minimal site preparation would be required for a mobile system and, in many cases,
properly graded access roads would be sufficient. Precipitated sludges may result
from this operation and would require dewatering and proper disposal. Minimal labor
would be required with automatic controls in place for metering pH control and
reagent addition. Power requirements include pumping, agitation, and, if ozone is
used, ozone generation. Water may be required for slurrying of solid materials.
5/93
10
-------
INORGANIC TREATMENT
Environmental Impacts
Sludges/residuals may need further treatment or offsite disposal (i.e., dewatering
solidification and/or landfilling). The system is operated in a closed vessel, so no air
pollution impacts would be expected. The treatment of contaminated materials from
the site will reduce the potential of offsite migration.
Costs
Capital costs for an aqueous waste treatment system can run from $200,000 up to
$2,000,000 for flow rates of 0.1 to 1.0 million gallons per day (MGD). Annual
operating and maintenance costs often approximate total capital costs; however, costs
may vary greatly depending on volume treated, composition of waste and required
treatment. Also, mobile systems may have high initial costs but the capital cost can
be spread over several sites. Potential rental of a mobile system could run from
$2,000-$10,000/month.
Commercial Applications
Rexnord has incorporated chemical oxidation (hypochlorite) into its mobile van
(groundwater cleanup response system) for pilot/full-scale cleanups.
For more information contact: Rexnord C.R.I.G.
5103 W. Beloit Rd.
P.O. Box 2022
Milwaukee, WI
414/643-2762
Neutralization
Neutralization is the interaction of an acid (pH < 5) or base (pH > 9) to adjust the pH of a
solution or mixture to between 5 and 9. It is achieved by adding either an acid or base to
a solution to obtain the desired pH. Neutralization can be used as a final waste treatment
process or as a pretreatment process to prepare a wastestream for further treatment. The
process of neutralization is widely used in commercial applications and has a wide range of
applicability for waste treatment. It is a simple process involving mixing the neutralization
agent with the waste, so it can be accomplished in almost any setting (e.g., mobile).
Sodium hydroxide, lime, or sulfuric acid are the most common components added to
neutralize a waste. The quantity and concentration will depend on the influent pH and the
desired effluent pH. The reaction products include water, salts and solids that may
precipitate out. FIGURE 2 presents a typical neutralization system.
5/93 11
-------
INORGANIC TREATMENT
|.H COK1ROILCR
MtUlRAUIAUOH TANK
2a
H£UTRALirATIOK
2b
ptt CONTROLLER
1
ALKALI rtto
I
6
K* « OH' • H;0 -f SALT
TRIM CO
CFFLUCIIT
(TO ClARIf IW
IF IICCCSSART)
2c
FIGURE 2
NEUTRALIZATION
5/93
12
-------
INORGANIC TREATMENT
Waste Type Handled
Neutralization is most often performed on liquids. It can also be performed on
sludges, slurries, and gases; organic and inorganic wastestreams; and spent acid and
alkali wastes with pH values below 4.0 and above 9.0. Contaminants can include
organic acids, metal alkali solutions, and other organic and inorganic wastes.
Concentration of the waste will determine the amount of neutralizing reagent
required. Buffer capacity of the waste will also affect the dosage requirements for
neutralization.
Restrictive Characteristics
Rapid mixing of contaminated materials containing cyanide, chlorides, etc. may
liberate toxic gases. High temperatures may result from the release of solution heat.
This may cause potential hazards. Solids and sludges may require excessive dosages
of chemicals because of limited mixing effectiveness and buffer capacity.
Mobile System Considerations
Neutralization requires simple off-the-shelf equipment that can easily be set up in a
mobile system. The equipment for neutralization usually consists of a chemical feed
system and a rapid mixing operation, followed by another physical/chemical process
for by-product removal (if necessary). The system is flexible and can be modified
into many different configurations depending on the specific waste material.
Minimal site preparation may be required (e.g., a properly graded access road).
Additional equipment may be needed for sludge disposal. However, additives should
be selected to reduce the quantity and toxicity of the generated sludge. Electricity
would be needed for pumping and mixing the wastes. Preparation of neutralizing
agents may require a water source (i.e., lime slaking). The resulting neutralized
wastestream may require additional processing.
Environmental Impacts
Toxic gases (e.g., ammonia, hydrogen sulfide, and hydrogen cyanide), may be
released if wastes are not mixed slowly and are not properly pretreated.
Neutralization may precipitate out heavy metals from solution and produce significant
quantities of sludge depending on the waste characteristics. Soil matrix and high
solids may produce chemical complexes that may not be effectively removed during
further processing. If both acid and alkali wastes are present on the site,
neutralization can be accomplished without the addition of offsite materials.
Neutralization is a simple treatment process that can reduce the hazardous nature of
corrosive wastes.
5/93 13
-------
INORGANIC TREATMENT
Costs
The capital and operating costs for neutralization depends on the specific process
selected. Capital costs for a permanent system can range from $400,000 for a 0.1
MGD system up to $15,000,000 for a 10 MGD system (including sludge disposal).
Operating costs can also vary widely because the major system components are
chemicals and labor. Neutralization has been incorporated into a complete mobile
water treatment system (softening, filtering, activated carbon, etc.) where costs for
rental of the complete package may be as high as $25,000/month for a 600 gpm
system.
Commercial Applications
Ecolochem, Inc. has incorporated neutralization (pH adjustment) into its water
treatment plant on wheels for cleanups of up to 600 gpm.
For more information contact: Ecolochem, Inc.
4545 Patent Rd.
P.O. Box 12775
Norfolk, VA 23502
800/446-8004
Precipitation
Chemical precipitation is a physiochemical process in which a dissolved contaminant is
transformed into an insoluble solid, facilitating its subsequent removal from the liquid phase
by sedimentation or filtration. The process usually involves (1) adjustment of pH to shift the
chemical equilibrium to a point that no longer favors solubility, (2) addition of the chemical
precipitant, and (3) flocculation in which precipitate particles agglomerate into larger particles
(FIGURE 3).
5/93 14
-------
VO
u>
2:
i
o
PrecipitoTion
Flocculatlon
Clarification
r>
H
Precipitating Chemicols
Flocculotlon end
Sedimentotion Aides
Inlef
Waste water
Rapid Mix Tank
o o
C
O-H
C
a era
Flocculotion Chamber
Clorlffer
4-
Sludge
Outlet
Stream
H
s
w
FIGURE 3
CHEMICAL PRECIPITATION AND ASSOCIATED PROCESS STEPS
-------
INORGANIC TREATMENT
This technology is well suited for detoxifying aqueous solutions containing toxic heavy
metals. A precipitating reagent is added to the solution to react with the heavy metals in
solution to form solid products which can then be removed by sedimentation or filtration.
Substances extensively employed to promote precipitation reactions include calcium oxide,
sodium sulfide, ferrous sulfide, sodium hydroxide, aluminum salts, carbonates, and
phosphates. Flocculating agents may be added to aggregate small particles into larger ones
that are then more easily removed.
Waste Type Handled
Precipitation has been extensively used to treat heavy-metal-bearing wastewaters.
The heavy metals include zinc, arsenic, cadmium, chromium, copper, lead, iron,
nickel, manganese, and mercury. Organics are not removed by this process. There
is no concentration limit for precipitation; however, highly viscous wastes will inhibit
settling. Solubility of metal salts as a function of pH will determine residual metal
in the wastewater.
Restrictive Characteristics
Organic compounds may interfere with precipitation by forming organometallic
complexes. Cyanide and other ions may also compile with metals, reducing the
precipitation potential or requiring much higher stoichiometric quantities of
chemicals.
Each metal salt has a different optimum pH for maximum removal and precipitation.
A mixed solution may require a trade-off on specific metals removals.
Mobile System Configurations
Equipment requirements include a reaction tank with rapid mixing, chemical storage
tanks, chemical feed pumps and pH controls that can be easily contained in a mobile
system. Additional equipment for the separation of liquid and solids will be required.
This may include clarification, filtration, or centrifugation. High-rate clarifiers are
ideal for mobile systems because of their compactness.
Minimal site preparation will be required for a mobile precipitation system (e.g., a
properly graded access road). Electric requirements may include pumping, mixing,
and sludge dewatering. The treated water from this process may require further
treatment for organic removal. The sludge generated from this process will contain
heavy metals.
Environmental Impacts
Proper mixing of the chemicals with the wastes and/or waste pretreatment should
minimize the potential releases of toxic gases. The generated sludge from this
process must be leach tested for EP toxicity, and appropriate treatment and disposal
5/93 16
-------
INORGANIC TREATMENT
of the sludge must be considered. This system can be incorporated into a
groundwater recovery system or as a wastewater regeneration step in a soil flushing
system.
Costs
The capital costs and operating costs for precipitation depend on the specific process
selected. Capital costs can range from $300,000 for a 0.1 MGD system up to
$2,000,000 for a 1.0 MGD that includes solids separation but not solids disposal.
Operating costs can vary widely because the major components are chemicals and
labor. Mobile wastewater treatment systems have been developed which include
neutralization, precipitation, sedimentation, filtration, and carbon adsorption. Costs
for rental of this complete package can range from $5,000 to $25,000/month
depending on flow rate.
Precipitation/Flocculation
General Description
Precipitation is a physiochemical process whereby some or all of a substance in
solution is transformed into a solid phase. It is based on alteration of the chemical
equilibrium relationships affecting the solubility of inorganic species. Removal of
metals as hydroxides or sulfides is the most common precipitation application in
wastewater in a rapid mixing tank along with flocculating agents (described below).
The wastewater flows to a flocculation chamber in which adequate mixing and
retention time is provided for agglomeration of precipitate particles. Agglomerated
particles are separated from the liquid phase by settling in a sedimentation chamber
and/or by other physical processes such as filtration. FIGURE 4 illustrates a typical
configuration for precipitation flocculation and sedimentation.
5/93 17
-------
INORGANIC TREATMENT
rioccucATiox
FMCIMTATlNC CHIMICALI—,
SCDIMINTATION
IHLTT II
1
A'
^
NO M
1 TANK
C
D^
r v
r
CMIMICAU THt rnicirrTATiON KIACTIOH
COMMINCit TO FORM VIRY (MA.U TAk.
iicut CAUID rMcirrTATioM NUCUI.
T*(l riOCCULATIMC AC1NTX ALLOW THCII
f ARTICLLt TO ACCLOMrKATt
r-AHTicitl. AIOIO IT
TMI PIOCCULATIHC ACIHTS. COLUDl.
ACCIOMIRATT. AND CHOW INTO LA*CC«
UTTXlAtU rARTICLIl
ouun nouio
JEIDIMINIATION KAIIN
TMt WTTUAHJ rAimCUf
• r TMI noccuiATiON rrrr ARI «muD.
COU.ICTTO AND rtniOOICAULT 01 MO VI 0
HGURE4
REPRESENTATIVE CONFIGURATION EMPLOYING PRECIPITATION,
FLOCCULATION, AND SEDIMENTATION
Source: DeRenzo, 1978
Although precipitation of metals is governed by the solubility product of ionic
species, in actual practice, effluent concentrations equal to the solubility product are
rarely achieved. Usually, the amount of lime that is added is about three times the
stoichiometric amount that would be added to reduce solubility due to the common
ion effect. FIGURE 5 gives solubilities of several metal hydroxides and sulfides at
various pH levels.
5/93
18
-------
INORGANIC TREATMENT
o
E
2
•o
c
o
O
10'
•6
n-8
ia
10
10-12
0 1
CuS
1 '
9 10 11 12 13
FIGURE 5
SOLUBILITY OF METAL HYDROXIDES AND SULFIDES
5/93
19
-------
INORGANIC TREATMENT
The metal sulfides have significantly lower solubility than their hydroxide
counterparts over a broad pH range. Many metal hydroxides, on the other hand, are
stable only over a narrow pH range; metals reach a minimum solubility at a specific
pH, but further addition of lime causes the metal to become soluble again.
Therefore, dosages of lime need to be accurately controlled. This may be
particularly challenging when working with aqueous wastes from waste disposal sites
where wide variations in flow rates and quantities of metals are present. The
stabilities of metal carbonates are also quite dependent on pH.
Flocculation is used to describe the process by which small, unsettleable particles
suspended in a liquid medium are made to agglomerate into larger, more settleable
particles. The mechanisms by which flocculation occurs involve surface chemistry
and particle charge phenomena. In simple terms, these various phenomena can be
grouped into two sequential mechanisms (Kiang and Metry, 1982):
• Chemically induced destabilization of the requisite surface-related forces, thus
allowing particles to stick together when they touch and
• Chemical bridging and physical enmeshment between the now nonrepelling
particles, allowing for the formation of large particles.
Flocculation involves three basic steps:
• Addition of flocculating agent to the wastestream
• Rapid mixing to disperse the flocculating agent
• Slow and gently mixing to allow for contact between small particles.
Typically, chemicals used to cause flocculation include alum, lime, various iron salts
(e.g., ferric chloride and ferrous sulfate), and organic flocculating agents, often
referred to as "polyelectrolytes." These materials generally consist of long-chain,
water-soluble polymers such as polyacrylamides. They are used either in conjunction
with the inorganic flocculants, such as alum, or as the primary flocculating agent.
A polyelectrolyte may be termed cationic, anionic, or ampholytic depending on the
type of ionizable groups, or nonionic if it contains no ionizable groups. The range
of physical/chemical characteristics (e.g., density, viscosity, toxicity, and molecular
weight) of the several thousand available polymers is extremely broad.
The inorganic flocculants, such as alum, lime, or iron salts, make use of precipitation
reactions. Alum (hydrated aluminum sulfate) is typically added to aqueous waste-
streams as a solution. Upon mixing, the slightly higher pH of the water causes the
alum to hydrolyze and form fluffy, gelatinous precipitates of aluminum hydroxide.
5/93 20
-------
INORGANIC TREATMENT
These precipitates, partially due to their large surface area, enmesh small particles
and thereby create larger particles. Lime and iron salts also have a tendency to form
large fluffy precipitates of "floe" particles.
Many precipitation reactions, such as the precipitation of metals from solution by the
addition of sulfide ions, do not readily form floe particles, but rather precipitate as
very fine and relatively stable colloidal particles. In such cases, flocculating agents
such as alum and/or polyelectrolytes must be added to cause flocculation of the metal
sulfide precipitates (Canter and Knox, 1985).
Once suspended particles have been flocculated into larger particles, they usually can
be removed from the liquid by sedimentation, provided a sufficient density difference
exists between the suspended matter and the liquid.
Applications/Limitations
Precipitation is applicable to the removal of most metals (e.g., zinc, cadmium,
chromium, copper, fluoride, lead, manganese, and mercury) from wastewater. Also,
certain anionic species (e.g., phosphate, sulfate, and fluoride can be removed by
precipitation.
Precipitation is useful for most aqueous hazardous wastestreams. However,
limitations may be imposed by certain physical or chemical characteristics. In some
cases, organic compounds may form organometallic complexes with metals, which
could inhibit precipitation. Cyanide and other ions in the wastewater may also
complex with metals, making treatment by precipitation less efficient.
Flocculation is applicable to any aqueous wastestream where particles must be
agglomerated into larger, more settleable particles prior to sedimentation or other
types of treatment. There is no concentration limit for precipitation or flocculation.
Highly viscous wastestreams will inhibit settling of solids.
In addition to being used to treat wastestreams, precipitation can also be used as an
in-situ process to treat aqueous wastes in surface impoundments. In an in-situ
application, lime and flocculants are added directly to the lagoon, and mixing,
flocculation, and sedimentation are allowed to occur within the lagoon. In some
cases, wind and pumping action can provide the energy for mixing.
Design Considerations
Selection of the most suitable precipitate or flocculent and their optimum dosages is
determined through laboratory jar test studies. In addition to determining the
appropriate chemicals and optimum chemical dosages, other important parameters
which need to be determined as part of the overall design include (Canter and Knox,
1985):
5/93 21
-------
INORGANIC TREATMENT
• Most suitable chemical addition system
• Optimum pH requirements
• Rapid mix requirements
• Sludge production
• Sludge flocculation, settling, and dewatering characteristics.
Technology Selection/Evaluation
Precipitation and flocculation are well-established technologies and the operating
parameters are well defined. The processes require only chemical pumps, metering
devices, and mixing and settling tanks. The equipment is readily available and easy
to operate. Precipitation and flocculation can be easily integrated into more complex
treatment systems.
The performance and reliability of precipitation and flocculation depend greatly on
the variability of the composition of the waste being treated. Chemical addition must
be determined using laboratory tests. In addition, chemical addition must be adjusted
and compositional changes of the waste must be treated or poor performance will
result.
Precipitation is nonselective in that compounds other than those targeted may be
removed. Both precipitation and flocculation are nondestructive and generate a large
volume of sludge which must be disposed of.
Precipitation and flocculation pose minimal safety and health hazards to field
workers. The entire system is operated at near ambient conditions, which eliminates
the danger of high pressure/high temperature operation encountered with other
systems. Whereas the chemicals employed are often skin irritants, they can easily
be handled in a safe manner.
Costs
TABLE 1 shows a breakdown of costs for the 40 gpm sulfex heavy metal
precipitation system illustrated in FIGURE 6.
The precipitator is sized to operate at a surface rate of 1.6 gpm/ft2 and the filter at
a surface rate of 3.2 gpm/ft2. Chemical costs for the Sulfex process and a hydroxide
precipitation process are shown in TABLE 2. These costs were estimated for
treatment of an influent containing 4 mg/1 Cu, Cd, Cr3"1", Ni, and Zri at pH 6.0.
5/93 22
-------
INORGANIC TREATMENT
TABLE 1
1985 CAPITAL COSTS* FOR SULFEX
HEAVY METAL PRECIPITATION SYSTEM
Equipment
Price
1. Precipitator with clear well, centrifuge for dewatering, chemical
feeds and agitators, and engineering drawings
2. Filter with transfer pump and engineering drawings
3. Neutralization system including agitators, chemical feeds, pH
controls, sump pump, and engineering drawings
TOTAL SELLING PRICE
Installation Cost (estimated by outside contractor)
TOTAL
$68,768
7,623
86,126
$162,517
66,657
$229,174
* Costs were updated to 1985 dollars using the 1983 and 1985 ENR Construction Cost Index.
Source: Metal Finisher's Foundation, 1977
5/93
23
-------
WASTE
CITY WAtER FOR FILTER BACKWASH
PUMP WITH STROKE
ADJUSTMENT
r
LIME
0
4
SHUT-OFF
Is
POLYMER
IRON SULFIOE
\
PRECIPITATOR
FILTER BACKWASH
EFFLUENT
CLEAR
WELL
€T
BLOWDOWH
CENTRIFUGE
SLUDGE
f l
4fl *
FILTER
TO SEWER
Z
o
I
0
I
FIGURE 6
40 GPM SULFEX PLANT FOR COMBINED REMOVAL OF Cr<+, An, Cu, Cd, Ni, and Fe
-------
INORGANIC TREATMENT
TABLE 2
COMPARISON OF CHEMICAL COSTS* OF
HYDROXIDE AND SULFIDE PRECIPITATION PROCESSES
Eff.
Qual.
(mg/1)
Chemical
Dosage
;ib/l,000 gal.
Cost
c/1,000 gal.
(1) Hvdroxide Process
Cu
Cd
Cr
Ni
Zn
PH7.5
0.1
3.8
< 0.5
2.3
1.3
U
Cu
Cd
Cr
Ni
Zn
Eff.
pH 10
< 0.1
< 0.1
< 0.1
< 0.1
< 0.1
Ca(OH)2
Polymer
H2S04
PH7.5
0.33
0.33
(2) Sulfex Process
Qual.
(mg/1)
PH8.5
0.01
0.1
< 0.05
0.05
0.01
Chemical
71 % NaHS
FeSo47H20
Polymer
Ca(OH)2
pH 10
0.92
0.03
0.61
c/lb pH7.5 pH 10
3.16 1.05 2.99
105.4 3.16 4.22
8.8 - 5.45
Total 4.21 12.66
Dosage
lb/1,000 gal.
pH 8.5
0.
0.
0.
1.
* Costs were updated to 1985 dollars using the 1977 and
09
77
03
13
Cost
C/l,OOOgal.
c/lb gH
19.77 1.76
3.95 2.99
105.4 3.16
3.16 3.51
Total 11.42
1985 ENR Construction Cost Index.
Source: Metal Finisher's Foundation, 1977
FIGURE 7 shows capital and operating costs for a flocculation system including
chemical storage, chemical feeding, and rapid mix. A polymer dosage of 1 mg/1 at
0.25-percent solution is assumed. Construction costs also include piping and building
to house the feeding equipment and bag storage.
5/93
25
-------
INORGANIC TREATMENT
CO9 1 j
TT
I ; i I? ' .... IT'
^Ezziirnff
iTTTi.
' I '
I I I
II
1C
W«u»w«l«-c
100
FIGURE?
FLOCCULATION OPERATING AND CAPITAL COSTS
Cyanide
Cyanide, as sodium cyanide (NaCN) or hydrocyanic acid (HCN), is a widely used industrial
material. Cyanide waste streams result from ore extracting and mining, photographic
processing, coke furnaces, synthetic fiber manufacturing, case hardening of steel, and
industrial gas scrubbing. Cyanide is produced as a side reactant in the catalytic cracking of
petroleum feed and in coking of distillation residues. A major source of waste cyanide is the
electroplating industry. Electroplaters use concentrated cyanide baths to hold metal!.: ions
such as cadmium, copper, and zinc in solution. Dragout of the plating solution, containing
cyanide ions and metal-cyanide complexes, contaminates rinsewater.
Several methods of treating cyanide wastes are in current use. The process most frequently
employed is cyanide destruction by chlorination. Cyanide may be either partially oxidized
to cyanate (CNO'), or completely oxidized to carbon dioxide (C02) and nitrogen (Nj).
Another cyanide destruction process, electrolytic decomposition, is applicable where waste
cyanide concentrations are very high, although new technology shows promise of application
to more dilute solutions. Ozone oxidation of cyanide has been employed with some success,
and is claimed to be equivalent to destruction by chlorination, on the basis of effectiveness
5/93
26
-------
INORGANIC TREATMENT
and costs. Evaporative recovery has also been successfully employed to treat cyanide
wastewaters. Other cyanide treatment processes, which are still primarily in the development
state, include reverse osmosis, ion exchange, and catalytic and thermal oxidation.
Destruction of cyanide by chlorination may be accomplished by direct addition of sodium
hypochlorite or by addition of chlorine gas plus sodium hydroxide to the waste. Sodium
hydroxide reacts with the chlorine to form sodium hypochlorite. Selection between the two
methods is on the basis of economics and safety. Chlorine gas treatment is about half as
expensive as direct hypochlorite addition, but handling is more dangerous and equipment
costs are higher. The hypochlorite added or produced oxidizes cyanide to cyanate.
Oxidation of cyanide to cyanate is accomplished most completely and rapidly under alkaline
conditions at pH 10 or higher, and this cyanide treatment process is often termed alkaline
chlorination. An oxidation period of 30 min-2 hr is usually allowed. To avoid solid cyanide
precipitates which may resist chlorination, the wastewater should be continuously agitated
during treatment. Close process control, utilizing pH and ORP sensors and automated
chemical feed techniques, is required to assure maximum reaction rate, minimum detention
time, and complete reaction (FIGURE 8).
1 Caustic Chlor
**** oK Controller *>*
1 p 1 1
\ 0
uyanioc j -*• — ii, , i / J
Liquid u J ' •/ — Ttg
Feed F^/ f
_^_ ' o4 T
ine
[L- Mixer
Jf=-
-> 7',.lL ^
tn
cfe Un
Covered, Jacketed Reactors
1st Stage 2nd Stage
(Increased
Destruction
Efficiency)
Column
Effluent
SOX
-* Reaction
used Chlorine
pture/Reactlon
FIGURE 8
SAMPLE CHEMICAL OXIDATION -
ALKALINE CHLORINATION (DESTRUCTION OF CYANIDE)
5/93
27
-------
INORGANIC TREATMENT
The resulting cyanate is much less toxic than cyanide, but can if necessary be further
oxidized to carbon dioxide and nitrogen. Oxidation of cyanate to carbon dioxide and
nitrogen can be accomplished by additional chlorination, or to carbon dioxide and ammonia
by acid hydrolysis. Acid hydrolysis must take place at pH 2-3, however, usually obtained
by addition of sulfuric acid. Thus, acid hydrolysis requires addition of acid to achieve the
required pH, and subsequent neutralization of the acidic wastewater before the effluent can
be discharged. These stages of pH adjustment increase the treatment costs as well as the
total dissolved solids of the wastewater. Cyanate will be destroyed by acid hydrolysis within
about 5 minutes of contact time.
Complete cyanide oxidation to CO2 and N2 can be accomplished solely through chlorination,
if close pH control is maintained. After initial oxidation to cyanate, further oxidation to
yield C02 and N2 will occur slowly over several hours at pH 10+. However, if the waste
pH is reduced to 8-8.5, cyanate oxidation by chlorine can be completed within 1 hour. At
the lower pH, sufficient chlorine must be added to ensure an excess beyond that needed to
oxidize the cyanide to cyanate, in order to avoid liberation of highly toxic cyanogen chloride
gas. Cyanogen chloride is the intermediate product of the oxidation of cyanide to cyanate.
It breaks down very rapidly at pH 10+ and temperatures above 20°C. However, at lower
pH or temperature, excess chlorine is needed to speed the breakdown. Complete cyanide
treatment at high pH, although requiring long reaction times, may be advantageous if the
treated wastewater can be utilized to neutralize acidic waste streams in the plant.
This process normally proceeds in two steps although it can proceed further in the presence
of excess chlorine, the cyanate reacting with more chlorine to form bicarbonate and nitrogen.
C12
Chlorine
2) CNC1
+NaCN
Cyanide
+2NaOH
Caustic Soda
Reaction of Cyanate with Chlorine
2NaCNO = 3C12 + 4H2O + 6NaOH
Overall Reaction
CNC1
Cyanogen
Chloride
NaCNO
Sodium
Cyanate
+NaCl
Sodium
Chloride
+HO + NaCl
2NaHCO3 + N2 + 6NaCl + 6H20
NaCN + 2.5C12 + SNaOH
NaHCO3 + O.5N + SNaCl + 2H0
Notice that the first step, which is almost instantaneous results in the formation of
cyanogen chloride which is a gas and is very toxic. This occurs regardless of pH.
It is therefore important to ensure that the reaction illustrated by the second equation
takes place to prevent the evolution of cyanogen chloride and this is done by ensuring
that the pH is at least as high as 8.5 and preferably as high as 10.5 to accelerate the
reaction. Also that 2.5 times as much chlorine is used if the cyanate is taken through
to the nitrogen stage.
5/93
28
-------
INORGANIC TREATMENT
However, it is unlikely that it would be necessary to take the reaction as far as this
since as mentioned earlier, the toxicity of sodium cyanate is so low that it is normally
acceptable to environmental authorities to discharge tailings water containing it into
water courses, etc. This is fortunate since as already mentioned, the amount of
chlorine required to take the reaction through to nitrogen and bicarbonate is 2.5 times
the amount necessary to take the reaction through to the cyanate only.
In addition to the reaction with cyanide, chlorine will react with thio salts such as
thiocyanate and thiosulfate. Therefore more than the theoretical 2.73 parts of C12 per
part of cyanide is normally required.
The potential hazards associated with chlorination are:
• The hazard due to chlorine itself which, however, is not a significant hazard
if the equipment is properly designed and the operators are properly trained,
and,
• The possibility of the formation of cyanogen chloride if there is not sufficient
alkalinity present to keep the pH over 8.5.
Costs
Capitol cost will vary with system design. TABLE 3 gives estimated cost for some
of the types of systems that are available. FIGURE 9 shows two different types of
cyanide destruction. These estimates do not include operating and maintenance
costs.
Commercial Applications
Rexnord, Ecolochem and Dravo all have complete wastewater treatment system on
wheels for cleanup.
For further information contact:
Rexnord C.R.I.G. Ecolochem Inc. Dravo Corp.
5103 W. Beloit Rd. 4545 Patent Rd. 412/777-5235
P.O. Box 2022 P.O. Box 12775
Milwaukee, WI Norfolk, VA 23502
414/643-2762 800/446-8004
5/93 29
-------
INORGANIC TREATMENT
TABLE 3
ESTIMATED COST FOR CYANIDE DESTRUCTION PLANTS
Package Plant System
15 gpm @ 450 ppm
30 gpm @ 350 ppm
$30,000 - $35,000
Batch Plant
2 gpm
30 gpm
$12,000
$30,000
2 Stage Units
15 gpm - 40 gpm
25 % additional for installation
$35,000 - $45,000
5/93
30
-------
INORGANIC TREATMENT
a.
CNO EFFLUENT
WASTE CN
RINSE
T '-'
n
1
_l
—
r*
i
-^
— i
\ i
.
J
^
i
T T
J
RECEIVING SUMP
b.
CHLORINATOR
CL,
WASTE CN
RINSE
e
.-t-,
-4-'
RECEIVING
SUMP
NaOH
CNO
NaOCL
CO»
EFFLUENT
FIGURE 9
COMMERCIAL PACKAGE PLANTS FOR CYANIDE WASTE TREATMENT.
a. Retention-tank package cyanide treatment plant.
b. Reaction-tower-type package cyanide treatment plant.
5/93
31
-------
INORGANIC TREATMENT
Ion Exchange and Sorptive Resins
General Description
Ion exchange is a process whereby the toxic ions are removed from the aqueous
phase by being exchanged with relatively harmless ions held by the ion-exchange
material. Modern ion-exchange resins are primarily synthetic organic materials
containing ionic functional groups to which exchangeable ions are attached. These
synthetic resins are structurally stable (i.e., can tolerate a range of temperature and
pH conditions), exhibit a high exchange capacity, and can be tailored to show
selectivity toward specific ions. Exchangers with negatively charged sites are cation
exchangers because they take up positively charged ions. Anion exchangers have
positively charged sites and, consequently, take up negative ions. The exchange
reaction is reversible and concentration dependent, and it is possible to regenerate the
exchange resins for reuse. Sorptive (macroporous) resins are also available for
removal of organics, and the removal mechanism is one of sorption rather than ion
exchange (Ghassemi, Yu, and Quinlivan, 1981).
Applications/Limitations
Ion exchange is used to remove a broad range of Sonic species from water, including:
• All metallic elements when present as soluble species, either anionic or
cationic
• Inorganic anions such as halides, sulfates, nitrates, and cyanides
• Organic acids such as carboxylics, sulfonics, and some phenols, at a pH
sufficiently alkaline to produce the ions
• Organic amines when the solution acidity is sufficiently acid to form the
corresponding acid salt (De Renzo, 1978).
Sorptive resins can remove a wide range of polar and nonpolar organics.
A practical upper concentration limit for ion exchange is about 2,500-4,000 mg/1.
A higher concentration results in rapid exhaustion of the resin and inordinately high
regeneration costs. Suspended solids in the feed stream should be less than SO mg/1
to prevent plugging the resins, and wastestreams must be free of oxidants (De Renzo,
1978).
5/93 32
-------
INORGANIC TREATMENT
Design Considerations
Specific ion-exchange and sorptive resins systems must be designed on a case-by-case
basis. It is useful to note that although there are three major operating models (fixed
bed concurrent, fixed bed counter current, and continuous countercurrent), fixed bed
countercurrent systems are most widely used. FIGURE 10 illustrates the fixed bed
countercurrent and continuous countercurrent systems. The continuous
countercurrent system is suitable for high flows. Complete removal of cations and
anions ("demineralization") can be accomplished by using the hydrogen form of a
cation exchange resin and the hydroxide form of an anion-exchange resin. For
removal of organics as well as inorganics, a combination adsorptive/demineralization
system, can be used. In this system, lead beds would carry sorptive resins that
would act as organic scavengers, and the end beds would contain anion- and cation-
exchange resins. By carrying different types of adsorptive resins (e.g., polar and
nonpolar), a broad spectrum of organics could be removed (Ghassemi, Yu, and
Quinlivan, 1981).
5/93 33
-------
INORGANIC TREATMENT
Types
Countercurrent Fixed Bed
Service Regeneration
Continuous Countercurrent
Description of
Process
Indications for use
Advantages
Disadvantages
Regeneration flows opposite in direction to
influent. Backwash (in regeneration) does
not occur on every cycle to preserve resin
stage heights. Resin bed is locked in place
during regeneration.
Handles high loads at moderate thruput or
low loads at high thruput (GPM x IDS or
GPM x PPM removal = 40,000 or more).
Where effluent quality must be relatively
constant, regeneration cost is relatively
critical, disposal of single batch waste
volume no problem. .
Moderate capital cost. Can be operated with
periodic attention. Moderate regeneration
cost. Lesser volume of waste due to less
frequent backwash. Consistent effluent
quality.
Increased controls and instrumentation,
higher cost. Requires mechanism to lock
resin bed. Large single batches of waste
disposal. Moderate water consumption thru
dilution and waste. Requires substantial
floor space.
Multistage Countercurrent movement of
resin in closed loop providing simultaneous
treatment, regeneration, backwash, and
rinse. Operation is only interrupted for
momentary resin pulse.
Highloads with high thruputs (GPM x IDS
or GPM x PPM removal = 40,000 or
more). Where constant effluent quality is
essential, regeneration costs critical, total
waste volume requires small, concentrated
stream to be controllable. Where loss of
product thru dilution and waste must be
minimized. Where available floor space is
limited.
Lowest regeneration cost. Lowest resin
inventory. Consistent effluent quality.
Highest thruput to floor space. Large
capacity units factory preassembled.
Concentrated low-volume wastestream.
Can handle strong chemical solutions and
slurry. Fully automatic operation.
Requires automatic controls and
instrumentation, higher capital cost. More
headroom required.
FIGURE 10
PERTINENT FEATURES OF ION EXCHANGE SYSTEMS
5/93
34
-------
INORGANIC TREATMENT
Technology Selection/Evaluation
Ion exchange is a well-established technology for removal of heavy metals and
hazardous anions from dilute solutions. Ion exchange can be expected to perform
well for these applications when fed wastes of variable composition, provided the
system's effluent is continually monitored to determine when resin bed exhaustion has
occurred. However, as mentioned previously, the reliability of ion exchange is
markedly affected by the presence of suspended solids. Use of sorptive resins is
relatively new and reliability under various conditions is not as well known.
Ion-exchange systems are commercially available from a number of vendors. The
units are relatively compact and are not energy intensive. Start-up or shut-down can
be accomplished easily and quickly (Ghassemi, Yu, and Quinlivan, 1981). These
features allow for convenient use of ion-exchange and sorptive resin systems in
mobile treatment systems.
Although exchange columns can be operated manually or automatically, manual
operation is better suited for hazardous waste site applications because of the diversity
of wastes encountered. With manual operation, the operator can decide when to stop
the service cycle and begin the backwash cycle. However, this requires use of a
skilled operator familiar with the process (Ghassemi, Yu, and Quinlivan, 1981).
Use of several exchange columns at a site can provide considerable flexibility. As
described previously, various resin types can be used to remove anions, cations, and
organics. Various columns can be arranged in series to increase service life between
regeneration of the lead bed or in parallel for maximum hydraulic capacity. The
piping arrangement would allow for one or more beds to be taken out for
regeneration while the remaining columns would remain in service. (Ghassemi, Yu,
Quinlivan, 1981).
Consideration must be given to disposal of contaminated ion-exchange regeneration
solution. In addition to proper disposal, another important operational consideration
is the selection of regeneration chemicals. Caution must be exercised in making this
selection to ensure the compatibility of the regenerating chemical with the waste being
treated. For example, the use of nitric acid to regenerate an ion-exchange column
containing ammonium ions results in the formation of ammonium nitrate, a potentially
explosive compound.
Costs
Costs for various sizes of ion-exchange units are presented in TABLE 4. The
construction costs assume fabricated steel contact vessels with baked phenolic linings,
a resin depth of 6 feet, housing for the columns, and all piping and backwash
facilities. Operation and maintenance costs include electricity for backwashing (after
150 bed volumes have been treated) and periodic repair and replacement costs. Costs
for regenerant chemicals are not included because they vary depending on the types
and concentrations of target chemicals to be removed from the wastewater.
5/93 35
-------
INORGANIC TREATMENT
TABLE 4
GENERAL COST DATA FOR VARIOUS SIZES OF EXCHANGE UNITS
Plant Capacity (gpm)
Construction Cost ($)'
Operation and
Maintenance Center
Costs ($/year)*
50
195
305
438
597
84,105
116,200
134,770
154,000
180,270
14,530
21,260
24,280
27,590
31,531
* Updated from 1979 to 1984 dollars using third quarter Marshall and Swift Index.
Ion Exchange
Anions and cations dissolved in an aqueous waste matrix can be removed from solution
through the process of ion exchange. As the name implies, one ion, electrostatically attached
to a solid resin material, is exchanged for a dissolved toxic ion. The exchange reaction is
reversible, which allows for resin regeneration, and occurs because of the increased affinity
the divalent and trivalent toxic metal anions or cations have for the charged sites on the
surface of the resins. These resins are originally coated with weakly held monovalent anions
or cations such as chloride, hydroxyl, sodium, or hydrogen ions.
It is possible to remove both dissolved, toxic anions and cations by placing a cation-exchange
column and anion-exchange column in series. This system has the capability, depending
upon the choice of resins, to remove a wide range of inorganic and organic dissolved
contaminants. These include:
• All metallic anions and cations such as
Cr2O7~, SeO4-, As04-, Ni2+, Cd2+, or Hg2+
• Inorganic anions such as halides, sulfates, and cyanides
• Organic acids such as carboxylics, sulfonics, and some phenols
• Organic bases such as amines.
5/93
36
-------
INORGANIC TREATMENT
These systems are commercially available from a number of vendors. They are compact,
do not require large energy inputs, and can be started up and shut down with relative ease.
An experienced operator is required for start-up, but the system can be operated in an
automatic mode once operational parameters are established for a particular waste.
Waste Types Handled
This process is applicable mainly as a polishing step for removing dissolved chemical
species. The species must be in an ionic form and should be free of suspended
solids, nondissolved organic liquids, and oxidizing agents such as perchlorates.
Metal plating and finishing industries use this technology as a waste management
strategy. Recovery of inorganic acids such as HNO3 and H2SO4 by chemical milling
operations has also recently been accomplished.
Restrictive Characteristics
Highly concentrated wastestreams containing contaminant levels greater than 2,500
mg/1 or suspended solid concentrations greater than 50 mg/1 should be avoided.
Otherwise, clogging of the column due to the solids or rapid resin exhaustion due to
the high levels of exchangeable species could occur. It should also be noted that this
technology, after regeneration, produces a concentrated contaminant solution that will
require consideration of additional disposal alternatives.
Mobile System Consideration
Small, trailer-mounted ion-exchange systems have been in operation since at least
1977. The typical range of pressure vessels are from 2- to 6- foot diameter systems
up to a custom size of 12 feet in diameter. Corresponding flow rates range from 25
gpm up to a maximum of 1,150 gpm. These vessels could easily be truck mounted
and moved from site to site.
Environmental Impacts
During resin regeneration, a concentrated toxic backwash stream is produced. This
stream could pose significant environmental impacts on water and air, if disposed of
improperly. Because of this, an ion-exchange system must, as part of a complete
system, fully address this potential threat. Depending on the waste characteristics,
additional treatment, storage, and disposal options must be considered, such as
precipitation/neutralization systems.
5/93 37
-------
INORGANIC TREATMENT
Costs
The costs of small, mobile, ion-exchange systems are not available. However, an
ion-exchange system servicing a flow of 50 gpm required an initial capital investment
of $84,000 and an annual Operation and Maintenance fee of $14,500. This cost is
based on 1984 dollars and will be less for mobile system designed for lower flows.
Commercial Applications
Since 1977, Eco-Tec Limited has marketed a skid-mounted,acid waste purification
and recovery system. They report a 50-percent (w/w) recovery of nitric acid from
a nickel-stripping process. A large number of companies market ion-exchange
systems (e.g., Eastman Kodak, Pennwalt Corp., VOP Inc., and Darcel Chemical
Industries), but these companies do not market a mobile system at this time.
5/93 38
-------
Section 8
-------
CARBON ADSORPTION
STUDENT PERFORMANCE OBJECTIVES:
At the conclusion of this section, participants will be able to:
• Briefly describe the advantages and disadvantages of carbon adsorption
• List at least three factors that influence the use of carbon adsorption systems
• List at least three design considerations for carbon adsorption systems
• Briefly describe typical carbon adsorption system operations
• Briefly describe the carbon regeneration process.
5/93
-------
NOTES
CARBON
ADSORPTION
CARBON ADSORPTION
Treatment Applies To:
• Polycyclic Aromatic Hydrocarbons
• Aromatic Ring/Cyclic Hydrocarbons
• Chlorinated Organic Compounds
(Volatiles and Extractables)
CARBON ADSORPTION
Chemical Characteristics
• Solubility Less Than 1% (Nonpolar)
• Molecular Weight > 50 Grams/Mole
(4 To 20 Carbon Atoms Work Best)
• Aromatics Better Than Aliphatics
(Double Or Triple Bonds Inhibit)
• Adsorptive Capacity At Least 50
Milligrams Per Gram of Carbon
5/93
Carbon Adsorption
page 1
-------
NOTES
CARBON ADSORPTION
Physical Phenomenon
• Chemisorption 0.99%
• Ionic Bonding 0.01%
• Van Der Waals Forces 99%
ACTIVATED CARBON
Starting Materials
• Bituminous Coal - Calgon
• Coconut Shells - Columbia
• Lignite - Darco
• Pulp Mill Residue - Nuchar
• Wood - Norit
ACTIVATED CARBON
Production
• Dehydration - Thermal and Chemical
Drives Off the Water
• Carbonization - Thermal/Limited Oxygen
Crystalizes Carbon
• Activation - Thermal and Steam
Drives Out Impurities and Leaves Pores
Carbon Adsorption
page 2
5/93
-------
NOTES
ACTIVATED CARBON
Pore Sizes
t 60% to 80% of the Pores < 40 Angstroms
• Macropores > 1000 Angstroms
• Micropores < 1000 Angstroms
• Iodine Number - 800 to 1200 (< 10
Angstroms)
• Molasses Number - 200 to 400 (< 28
Angstroms)
ACTIVATED CARBON
Physical Characteristics
• Bulk Density 26 to 40 Lbs. Per Cubic Foot
• Pore Volume .70 to .90 cc Per Gram
• 70% to 90% Void Space
• Effective Sizes - .55 to 1 mm Gac
.15 to .55 Pac
ACTIVATED CARBON
Surface Area
• 500 to 1400 Square Meters Per Gram
• 150 Acres Per Pound
5/93
Carbon Adsorption
page 3
-------
NOTES
ACTIVATED CARBON
Applications
• Aqueous Phase Materials
• Vapor Phase Materials
ACTIVATED CARBON
Aqueous System Design
• Suspended Solids < 50 ppm
• Grease and Oil Removed
• Temperature Variable
• pH Variable
• Parallel or Series Arrangement
ACTIVATED CARBON
Aqueous System Design
• Upflow Systems (Pressure)
Expanded Bed - Continuous Backwash
Pulsed Bed - No Backwash
• Downflow Systems (Pressure or Gravity)
Require Special Backwash
Effluent Quality Varies
Most Common Mobile Design
• Sizes From 50 to 5000 GPM
Carbon Adsorption
page 4
5/93
-------
NOTES
ACTIVATED CARBON
Vapor Phase System Design
• Humidity < 50%
• Operating Temperature < 250 F
• Flow Rates 10 to 200 CFM
• Suspended Solids and Grease/Oil
Removal Similar to Aqueous Systems
ACTIVATED CARBON
Field Setup
• Prewet with Clean Water for 24 Hours
(Aqueous Systems)
• Pretreat for the Following:
- Suspended Solids and Greases/Oils
- Scale-Forming Inorganics and Iron
- Bacteria
• Use Compatible Plumbing
ACTIVATED CARBON
Field Operation
• Do Not Exceed Design Flow Rates and
Pressures
• Backwash Regularly
• Monitor Effluent
5/93
Carbon Adsorption
page 5
-------
NOTES
ACTIVATED CARBON
Waste Treatment
Backwash Water (To Aqueous Treatment)
Spent Carbon
Some Contaminants Need Special
Handling
Land Bans May Apply
BEFORE USE Check with Disposal Facility
ACTIVATED CARBON
Carbon Regeneration
• Desorb Organics - Thermal
(Generally, Desorbed Organics are
Destroyed by Combustion)
• Reactivate Carbon - Thermal and Steam
(Reactivation Restores about 85% to 90%
Capacity)
ACTIVATED CARBON
Costs
• Cost of Carbon Per Pound
- $1.05 to $1.30 for Virgin Carbon
- $0.85 to $1.10 for Regenerated Carbon
• Total Costs Per 1000 Gallons Treated
- $0.22 to $0.55 (Influent in ppb)
- $0.48 to $2.50 (Influent in ppm)
Carbon Adsorption
page 6
5/93
-------
CARBON ADSORPTION
Activated Carbon Treatment
General Description
The process of adsorption onto activated carbon involves contacting a waste stream
with the carbon, usually by flow through a series of packed bed reactors. The
activated carbon selectively adsorbs hazardous constituents by a surface attraction
phenomenon in which organic molecules are attracted to the internal pores of the
carbon granules.
Adsorption depends on the strength of the molecular attraction between adsorbent and
adsorbate, molecular weight, type and characteristic of adsorbent, electrokinetic
charge, pH, and surface area.
Once the micropore surfaces are saturated with organics, the carbon is "spent" and
must either be replaced with virgin carbon or removed, thermally regenerated, and
replaced. The time to reach "breakthrough," or exhaustion, is the single most critical
operating parameter. Carbon longevity balanced against influent concentration
governs operating economics.
Most hazardous waste treatment applications involve the use of adsorption units that
contain granular activated carbon (GAC) and operate in a downflow series mode such
as that shown in FIGURE 1 (Brunotts et al., 1983).
The downflow fixed bed series mode is usually the most cost-effective and produces
the lowest effluent concentrations relative to other carbon adsorption configurations
(i.e., downflow in parallel, moving bed, and up flow-expanded). The units may be
connected in parallel to provide increased hydraulic capacity.
Applications/Limitations
Activated carbon is a well-developed technology that widely used in the treatment of
hazardous wastestreams. It is especially well suited for removal of mixed organics
from aqueous wastes. TABLE 1 provides an indication of the treatability of organics
commonly found in groundwater.
TABLE 2 delineates various factors that influence the applicability of activated
carbon treatment for any given waste (Nalco Chemical Co., 1979). Because carbon
adsorption is essentially an electrical interaction phenomenon, the polarity of the
waste compounds will largely determine the effectiveness of the adsorption process.
5/93
-------
CARBON ADSORPTION
Highly polar molecules cannot be effectively removed by carbon adsorption. Another
factor to consider in determining the likely effectiveness of carbon adsorption is
aqueous solubility. The more hydrophobic (insoluble) a molecule is, the more readily
the compound is adsorbed. Low solubility humic and fulvic acids which may be
present in the groundwater can sorb to the activated carbon more readily than most
waste contaminants and result in rapid carbon exhaustion.
FEED WATER
REGENERATED/MAKEUP
ACTIVATED CARBON '
BACK WASH EFFLUENT
BACK WASH FEED
ADSORBER I
ADSORB Eft I
REGENERATED'MAKEUf
ACTIVATED CARBON
BACKWASH EFFLUENT
BACK WASH FEED
TREATED EFFLUENT
J
VALVE CLOSED
VALVE OPEN
FIGURE 1
TWO-VESSEL GRANULAR CARBON ADSORPTION SYSTEM
5/93
-------
CARBON ADSORPTION
TABLE 1
FACTORS AFFECTING EQUILIBRIUM
Compound adsorbability favored by:
Increasing carbon chain length
Increasing aromaticity
Decreasing polarity
Decreasing branching
Decreasing solubility
Decreasing degree of dissociation
Functionality:
Relative adsorbability: acids > aldehydes > esters > ketones >
alcohols > glycols when number of carbon atoms is < 4
pH effects:
Undissociated species are more easily adsorbed
- Low pH favors adsorption of acids (e.g., volatile acids,
phenol)*
- High pH favors adsorption of bases (e.g., amines)
Other compounds: adsorption can be favored by higher pH
- Postulated general effect:
Partial neutralization of surface acidity reduces
hydrogen-bonding of surface groups eliminating steric
blockage of micropores
Temperature:
Increased temperatures can increase rate of adsorption due to viscosity
and diffusivity effects
Exothermic adsorption reactions are favored by decreasing temperatures,
usually a minor effect on equilibrium level
"This often is the most significant pH effect, so adsorption generally is increased with
decreasing pH.
Source: Conway and Ross, 1980
5/93
-------
CARBON ADSORPTION
TABLE 2
CARBON INFLUENT AND EFFLUENT
Organic Compounds in
Groundwater
Carbon tetrachloride
Chloroform
ODD
DDE
DDT
cis-1 ,2-Dichloroethylene
Dichloropentadiene
Diisopropyl methylphosphonate
Tertiary methyl-butylether
Diisopropyl methylphosphonate
1 ,3-Dichloropropene
Dichloroethyl ether
Dichloroisopropylether
Benzene
Acetone
Ethyl acrylate
Trichlorotriflorethane
Methylene chloride
Phenol
Orthochlorophenol
Tetrachloroethylene
Trichloroethylene
1,1, 1-Trichloroethane
Vinylidiene chloride
Toluene
Xylene
Number
of
Occurrences
4
5
1
1
1
8
1
2
1
1
1
1
1
2
1
1
1
2
2
1
10
15
6
2
1
3
Influent*
Concentration
Range
130 Mg/1-10 mg/1
20 Mg/1-3.4 mg/1
lMg/1
lMg/1
4 Mg/1
5 /xg/1-4 mg/1
450 Mg/1
20-4 Mg/1
33 Mg/1
1,250 Mg/1
10 Mg/1
1.1. mg/1
0.8 mg/1
0.4-1 mg/1
10-100 fig/I
200 mg/1
6 mg/1
1-21 mg/1
63 mg/1
100 mg/1
5 /xg/1-70 mg/1
5 Mg-16 mg/1
60 Mg/1-25 mg/1
5 Mg/1-4 mg/1
5-7 mg/1
0.2-10 mg/1
Carbon Effluent*
Concentration
Achieved
< 1 Mg/1
< 1 Mg/1
<0.05g/l
< 0.05 Mg/1
<0.05 Mg/1
< 1 Mg/1
< 10 Mg/1
< 1 Mg/1
< 5.0 Mg/1
< 50 Mg/1
< 1 MS/1
< 1 Mg/1
< 1 Mg/1
< 1 Mg/1
< 10 mg/1
< 1 mg/1
< 10 Mg/1
< 100 Mg/1
< 1 Mg/1
< 1 mg/1
< 1 Mg/1
< 1 Mg/1
< 1 Mg/1
< 1 Mg/1
< 10 Mg/1
< 101 Mg/1
* Analyses conducted by Calgon Carbon Corporation conformed to published U.S. EPA protocol methods.
Tests in the field were conducted using available analytical methods.
In addition, some metals and inorganic species have shown excellent to good
adsorption potential, including antimony, arsenic, bismuth, chromium, tin, silver,
mercury, cobalt, zirconium, chlorine, bromine, and iodine.
Carbon adsorption is frequently used following biological treatment and/or granular
media filtration to reduce the organic and suspended solids load on the carbon
columns or to remove refractory organics that cannot be biodegraded. Air stripping
may also be applied prior to carbon adsorption to remove a portion of the volatile
5/93
10
-------
CARBON ADSORPTION
contaminants, thereby reducing the organic load to the column. These pretreatment
steps all minimize carbon regeneration costs.
The highest concentration of solute in the influent stream that has been treated on a
continuous basis is 10,000 ppm total organic carbon (TOC). A 1-percent solution is
currently considered the upper limit (De Renzo, 1978). Pretreatment is required for
oil and grease and suspended solids. Concentrations of oil and grease in the influent
should be limited to 10 ppm. Suspended solids should be less than 50 ppm for
downflow systems, whereas upflow systems can handle much higher solids loadings.
Design Considerations
The phenomenon of adsorption is extremely complex and not mathematically
predictable. To accurately predict performance, longevity, and operating economics,
field pilot plant studies are necessary.
To conduct an initial estimate of carbon column sizing, the following data need to be
established during pilot plant testing:
• Hydraulic retention time (hours)
• Flow (gallons/minute)
• Hydraulic capacity of the carbon (gallons waste/pounds carbon)
• Collected volume of treated waste at breakthrough (gallons)
• Carbon density (pounds carbon/cubic foot).
"Breakthrough" refers to the moment when the concentration of solute being treated
first starts to rise in the carbon unit effluent. "Exhaustion" refers to the moment
when the concentration of solute being treated is the same in both the effluent and the
influent.
Technology Selection/Evaluation
Activated carbon is an effective and reliable means of removing low-solubility
organics. It is suitable for treating a wide range of organics over a broad
concentration range. It is not particularly sensitive to changes in concentrations or
flow rate and, unlike biological treatment, is not adversely affected by toxics.
However, it is quite sensitive to suspended solids and oil and grease concentrations.
Activated carbon is easily implemented into more complex treatment systems. The
process is well suited to mobile treatment systems as well as to onsite construction.
Space requirements are small, start-up and shut-down are rapid, and there are
numerous contractors who are experienced in operating mobile units.
5/93 11
-------
CARBON ADSORPTION
EPA's Mobile Physical/Chemical Treatment System includes three carbon columns
that can be operated either in series or in parallel. They are designed for a hydraulic
loading of 200 gpm with a 27 minute contact time. This contact time has been found
to be adequate for many hazardous wastestreams. However, longer contact times can
be provided by reducing the hydraulic flow rate.
Use of several carbon adsorption columns at a site can provide considerable
flexibility. Various columns can be arranged in series to increase service life
between regeneration of the lead bed or in parallel for maximum hydraulic capacity.
The piping arrangement would allow for one or more beds to be regenerated while
the other columns remain in service.
The most obvious maintenance consideration associated with activated carbon
treatment is the regeneration of spent carbon for reuse. Regeneration must be
performed for each column at the conclusion of its bedlife so that the spent carbon
may be restored as close as possible to its original condition for reuse. If the spent
carbon is not regenerated, it must be disposed of. Other operation and maintenance
requirements of activated carbon technology are minimal if appropriate automatic
controls have been installed.
The thermal destruction properties of waste chemicals must be determined prior to
selection of activated carbon treatment technology. This determination must be made
because any chemicals sorbed to activated carbon must eventually be destroyed in a
carbon regeneration furnace. Therefore, of crucial importance to the selection of
activated carbon treatment is whether the sorbed waste material can be effectively
destroyed in the regeneration furnace; otherwise, upon introduction to the furnace,
the waste materials will become air pollutants.
The biggest limitation of the activated carbon process is the high capital and operating
costs. As described previously, the operating costs can be substantially reduced by
pretreatment of the waste using biological treatment or air stripping.
Costs
The cost of activated carbon units depends on the size of the contact unit, which is
influenced by the concentrations of the target and nontarget organic compounds in the
wastestream and the desired level of target compounds in the effluent. TABLE 3
presents construction, operation, and maintenance costs for cylindrical, pressurized,
downflow steel contactors based on a nominal detention time of 17.5 minutes and a
carbon loading rate of 5 gpm/ft2. The construction costs include housing; concrete
foundation; all necessary pipes, valves, and nozzles for operating the unit; and the
initial change of carbon. The operation and maintenance costs include electricity and
assume carbon replacement once a year. However, systems for unloading spent
carbon and loading fresh carbon are not included.
5/93 12
-------
CARBON ADSORPTION
TABLE 3
GENERAL COST DATA FOR VARIOUS SIZES OF ACTIVATED
CARBON CONTACT UNITS
Capacity
"jf (gpiri);, ;>
1.7
17
70
175
350
Column
iDiameter (ft)
0.67
2
4
6.5
9
Column
Length (ft)
5
5
5
5
5
Housing
Area (ft2)
60
150
300
375
450
Construction
Costs*
12,320
23,776
42,425
64,000
93,822
O&M
Costs (F/yr)*
1,690
2,315
4,800
8,110
12,540
* Updated from 1979 to 1984 dollars using third quarter Marshall and Swift Equipment
Index.
A number of manufacturers market mobile, activated carbon treatment systems. For
example, Calgon Carbon Corporation has a trailer-mounted, carbon adsorption
treatment unit that can be shipped to a treatment location within 24-48 hours. This
system can be configured with either single or multiple prepiped adsorber vessels.
It can handle flows up to 200 gpm. The following costs are associated with a mobile
system consisting of two 10-foot diameter, 10-foot high, skid-mounted vessels
capable of handling up to 200 gpm (Calgon Carbon Corp., undated):
Delivery, supervision of installation
and startup, tests to conduct reacti-
vation of carbon, dismantling and
removal of system (including freight to
and from the site)
Delivery and removal of one truckload
of carbon (2,000 Ibs)
(Two truckloads required for a two-
vessel system) - Rental fee (per
month)
$25,000
$15,200
$5,000/month
5/93
13
-------
CARBON ADSORPTION
Activated Carbon Adsorption
Process Description
Activated carbon, either alone or in combination with other processes, is the most
frequently applied technology for the removal of trace organic compounds from
contaminated water. Carbon adsorption has been used in granular form in contact
beds (fixed or pulsed bed reactors) and in powdered form in aerobic biological
treatment. The overall principle behind this treatment process is the surface attraction
phenomena between the organic solutes and the large, internal pore surface area of
the carbon grains.
The carbon adsorption process is dependent on the physical characteristics of the
carbon and the molecular size of the adsorbates. Because adsorption is a surface
phenomenon, a large surface area, typical of activated carbon (500-1400 m2/g), is
beneficial for an effective removal of organic compounds. Activated carbon will
adsorb most organic compounds to some degree; however, it is most effective for the
least polar and least soluble organic compounds. Other factors that affect the
adsorption process include liquid pH and temperature, carbon pore structure, and
liquid/carbon contact time. FIGURE 2 depicts a typical carbon adsorption system.
Waste Type Handled
Carbon adsorption can be applied to aqueous and gaseous wastes containing a wide
range of organic compounds. Refractory organics, volatile organics, pesticides,
organic nitrogen compounds, and chelated heavy metals can be successfully removed
from an aqueous stream. Removal is enhanced by low water solubility and nonpolar
characteristics of the organics. Adsorption capacities of >50 mg/g carbon at influent
concentrations of 1,000 ^g/1 are usually required for economical operations.
Restrictive Characteristics
High solids content (^50 mg/1) cannot be tolerated because of potential clogging of
columns. Unassociated metals and highly miscible organic compounds will not be
removed by this process. Mixtures of organics may cause significantly reduced
adsorption capacity because of chromatographic effects. Vapor phase carbon cannot
tolerate a high humidity gas stream (^50%) because the active pores are blocked by
water.
5/93 14
-------
CARBON ADSORPTION
CARDON MAKE-UP
TO CARBON
REGENERATION
SYSTEM
CARDON DED
INFLUENT WATER
WATER
O
HIGH PRESSURE SPENT CARBON SLURRY
WATER
Mk**UtM|Mlt|M
CARBON BED
z
EFFLUENT
(TREATED WATER)
FIGURE 2
GRANULAR ACTIVATED CARBON COLUMNS
Mobile System Considerations
Carbon contacting beds can be skid mounted and placed on flatbed trucks or railcars
for transportation to various sites. Gravity flow and multicolumns in series are the
most commonly designed contacting systems. Single units can handle up to 20,000
Ibs of carbon. Some units may be larger. Additional required equipment will consist
of pumps, piping for various configurations (e.g., in series or parallel), backwashing
equipment, carbon transfer equipment, and, potentially, carbon regeneration
equipment (which is also available in a mobile unit). Hydraulic loading contact time
and breakthrough characteristics are key operating parameters for the design of a
system.
5/93
15
-------
CARBON ADSORPTION
Environmental Impacts
The exhausted carbon contains all of the removed waste and must be either
regenerated (onsite or offsite) or disposed of in a secure landfill (carbon with PCBs
or dioxin will not currently be regenerated by the vendors). Thermal regeneration
of the used carbon is the most common method currently used. However, solvent
and steam regeneration are also employed. Periodic backwashing of the carbon will
require holding tanks for the liquids, which can be sent back through the carbon once
the solids have settled. This small amount of sludge will need to be disposed of.
Slurrying of carbon during changeouts will cause high abrasion of the equipment.
Costs
Capital costs for two in-series carbon contactors with 20,000 pounds in each, can
range from $200,000 to $500,000 depending on the application. Operating costs are
heavily dependent on the carbon usage rate because carbon changes are the largest
cost factor.
Commercial Applications
EPA has an emergency environmental response unit (mobile system) nicknamed the
"Blue Magoo" that contains three sand filters followed by three in-series GAC
columns. The system has operated at over 20 different sites. Many commercial
services companies and vendors supply mobile carbon adsorption systems. A partial
list follows:
EPA/Releases Control Branch OH Materials
Woodbridge Avenue Nationwide
Edison, NJ 08837 419/423-3526
201/321-6677
Mobile Industrial Services Chemical Waste Management
Louisville, KY Oak Brook, IL
800/626-2564 714/940-7971
Calgon Corp. Newpark Waste Management
Bridgewater, NJ Lafayette, LA
201/526-4646 713/963-9107
5/93 16
-------
Section 9
-------
BIOLOGICAL TREATMENT
STUDENT PERFORMANCE OBJECTIVES:
At the conclusion of this unit, participants will be able to:
• Briefly describe the advantages and disadvantages of biological treatment
• List and describe at least three factors that influence biodegradation of wastes
• State the difference between aerobic and anaerobic biological treatment
• Briefly describe a typical aerobic treatment system
• Briefly describe the in-situ biodegradation process.
5/93
-------
NOTES
BACTERIA
Biodegradation of Hazardous Materials
OH
y\
Mineralization
Phenol
C02+ H20
Aerobic Harmless
Respiration End Product
ADVANTAGES OF BIOREMEDIATION
• Effective in removing hydrocarbons
and selected organic contaminants
• Environmentally sound
• Inexpensive
• Effective for short-term treatment
of contaminated water
DISADVANTAGES OF BIOREMEDIATION
• Not effective for heavy metals
or some chlorinated compounds
• Operating and maintenance costs
relatively high
• Long-term effectiveness unknown
• Possible adverse public reaction
5/93
Biological Treatment
page 1
-------
NOTES
RESPIRATION PROCESSES
c
Aerobic Respiration
C6H1206 + 602 *> 6C02 + 6H2
Anaerobic Respiration
8H1206+12NO>
6C02+6H20 + 12N<
0 + 38 ATP
BIOLOGICAL TREATMENT MICROBES
• Bacteria
Bacillus
Micrococcus
• Actinomycetes
Streptomyces
Nocardia
• Fungi
Aspergillus
Acremonium
CHEMICAL CONCENTRATION
GROWTH-SUPPORTING SUBSTRATE
^^^^^^ I Microbial
^^W / Population
^r \ Chemical
^^^ % Contaminant
TIME
Biological Treatment
page 2
5/93
-------
NOTES
NONGROWTH-SUPPORTING SUBSTRATE
0
CHEMICAL CON
-
--—— ""TT
•^•B
Chemical Contaminant
Microbial Population
mmmimf
TIME
COSUBSTRATE ADDITION
;ENT RATION
*
8
_j
UJ
I
O
1 \.
^\>
A
y
*s
TIME
1 Microbial
I Population
\ Chemical
1 Contaminant
ANALYSIS OF A REPRESENTATIVE SAMPLE
Determine:
• Total bacterial
• Nutrient level
• pH
population
• Chemical constituents
• Moisture
* Temperature
• Oxygen requirements
5/93
Biological Treatment
page 3
-------
NOTES
BIODEGRADATION POTENTIAL
Organic Contaminant
Toxicity Assessment
Done By
Electrolytic Respirometer
ELECTROLYTIC RESPIROMETER
VESSELS
NUMBER CONTENTS
Sample + Natural Flora
Sample + Selected Microbes (Augmentation Sample)
Sample + Indigenous Microbes (Indigenous Control)
Negative (Sterile) Control (Sample + HgCI 2, KCN, NaN3)
Sample + Selected Microbes + Glucose
(Positive Control)
6 Selected Microbes + Glucose
ER-2
ER-1
Time
Biological Treatment
page 4
5/93
-------
NOTES
CONSIDERATIONS FOR BIOREMEDIATION
• Identify contaminant
• Delineate contaminant plume
• Identify contaminant concentration within plume
• Determine rate of flow of groundwater
• Determine nutrient and oxygen requirements
• Determine type and physical properties of
geologic materials
LANDFILL DISPOSAL VS.
IN-SITU BIOLOGICAL TREATMENT
7,500 yd3
Contaminated Soil
100 miles transportation at
$4/mile for disposal at
$100/yd>
$900,000 Landfill Disposal
•$300,000 Biological Treatment
$600,000 cost benefit for
Biological Treatment
Cross Section of an In-Situ Biodegradation System
Recovery Well
Confining Bed
5/93
Biological Treatment
page 5
-------
NOTES
Oxygen Source
INJECTION SYSTEM
Pressure
Gauge
Nutrients
BIOLOGICAL TREATMENT SYSTEM
BIOLOGICAL TREATMENT PROGRAM
• Innoculation of contaminated area
with the appropriate microbes
• Aeration
• Nutrient addition
• Monitoring air quality
(volatile emissions)
• Monitoring chemical parameters
• Monitoring biological activity
Biological Treatment
page 6
5/93
-------
BIOLOGICAL TREATMENT
Biological Treatment
General Description
The function of biological treatment is to remove organic matter from the waste-
stream through microbial degradation. The most prevalent form of biological
treatment is aerobic (i.e., in the presence of oxygen). A number of biological
treatment processes exist that may be applicable to treatment of aqueous wastes from
hazardous waste sites. These processes include conventional activated sludge; various
modifications of the activated sludge process, including pure oxygen activated sludge,
extended aeration, and contact stabilization; and fixed film systems that include
rotating biological discs and trickling filters.
In the conventional activated sludge process, aqueous waste flows into an aeration
basin where it is aerated for several hours. During this time, a suspended active
microbial population (maintained by recycling sludge) aerobically degrades organic
matter in the stream and produces new cells. A simple equation for this process is:
Organics + O2 -» CO2 + H2O + new cells
The new cells produced during aeration form a sludge that is settled out in a clarifier.
A portion of the settled sludge is recycled to the aeration basin to maintain the
microbial population while the remaining sludge is wasted (i.e., it undergoes volume
reduction and disposal). Clarified water flows to disposal or further processing.
In the pure oxygen activated sludge process, oxygen or oxygen-enriched air is used
instead of air to increase the transfer of oxygen. Extended aeration involves longer
detention times than conventional activated sludge and relies on a higher population
of microorganisms to degrade wastes. Contact stabilization involves only short
contact of the aqueous wastes and suspended microbial solids, with subsequent
settling of sludge and treatment of the sludge to remove sorbed organics. Fixed film
systems involve contact of the aqueous wastestream with microorganisms attached to
some inert medium such as rock or specially designed plastic material. The original
trickling filter consisted of a bed of rocks over which the contaminated water was
sprayed. The microbes forming a slime layer on the rocks would metabolize the
organics, while oxygen was provided as air moved countercurrent from the water
flow (Canter and Knox, 1985).
Biological towers are a modification of the trickling filter. The medium (e.g.,
poly vinyl chloride [PVC], polyethylene, polystyrene, or redwood) is stacked into
towers which typically reach 16 to 20 ft. The contaminated water is sprayed across
the top and, as it moves downward, air is pulled upward through the tower. A slime
layer of microorganisms forms on the media and removes the organic contaminants
as the water flows over the slime layer.
5/93
-------
BIOLOGICAL TREATMENT
A rotating biological contactor (RBC) consists of a series of rotating discs, connected
by a shaft, set in a basin or trough. The contaminated water passes through the basin
where the microorganisms, attached to the discs, metabolize the organics present in
the water. Approximately 40 percent of the discs' surface area is submerged as it
rotates. This allows the slime layer to alternately come in contact with the
contaminated water and the air where oxygen is provided to the microorganisms
(Canter and Knox, 1985).
Applications/Limitations
There is considerable flexibility in biological treatment because of the variety of
available processes and adaptability of the microorganisms themselves. Many organic
chemicals are considered biodegradable, although the relative ease of biodegradation
varies widely. Several generalizations can be made with regard to the ease of
treatability of organics by aerobic biological treatment:
• Unsubstituted nonaromatics or cyclic hydrocarbons are preferred over
unsubstituted aromatics.
• Materials with unsaturated bonds such as alkenes are preferred over materials
with saturated bonds.
• Soluble organics are usually more readily degraded than insoluble materials.
Biological treatment is more efficient in removing dissolved or colloidal
materials, which are more readily attacked by enzymes. This is not the case,
however, for fixed-film treatment systems that preferentially treat suspended
matter.
• The presence of functional groups affects biodegradability. Alcohols,
aldehydes, acids, esters, amides, and amino acids are more degradable than
corresponding alkanes, olefins, ketones, dicarboxylic acids, nitriles, and
chloroalkanes.
• Halogen-substituted compounds are the most refractory to biodegradation;
chlorinated alphatics are generally more refractory than the corresponding
aromatics, although the number of halogens and their position is also
significant in determining degradation.
• Nitro-substituted compounds are also difficult to degrade although they are
generally less refractory than the halogen-substituted compounds.
Although there are a number of compounds that are considered to be relatively
resistant to biological treatment, it is recommended in practice that the treatability of
waste be determined through laboratory biological oxygen demand (BOD) tests on a
case-by-case basis.
5/93
-------
BIOLOGICAL TREATMENT
Despite the fact that industrial wastes may be refractory to biological treatment,
microorganisms can be acclimated to degrade many compounds that are initially
refractory. Similarly, whereas heavy metals are inhibitory to biological treatment,
the biomass can also be acclimated, within limits, to tolerate elevated concentrations
of metals.
TABLE 1 presents the biological treatment processes available and the applications
and limitations of each. The completely mixed activated sludge process is the most
widely used for treatment of aqueous wastes with relatively high organic loads.
However, the high-purity oxygen system has advantages for hazardous waste site
remediation.
TABLE 1
SUMMARY OF APPLICATIONS/LIMITATIONS
FOR BIOLOGICAL TREATMENT PROCESS
Process
Conventional
Completely Mixed Conventional
Extended Aeration
Contact Stabilization
Pure Oxygen
Trickling Filters
Rotating Biological Disc
Applications/Limitations
Applicable to low-strength wastes; subject to shock loads
Resistant to shock loads
Requires low organic load and long detention times; low volume
of
Not suitable for soluble BOD
Suitable for high-strength wastes; low sludge volume reduced
More effective for removal of colloidal and suspended BOD; used
Can handle large flow variations and high organic shock loads;
In addition, a number of other parameters may influence the performance of the
biological treatment system. These are concentration of suspended solids, oil and
grease, organic load variations, and temperature. TABLE 2 lists parameters that
may limit system performance, limiting concentrations, and the type of pretreatment
steps required prior to biological treatment.
Design Considerations
Design of the activated sludge or fixed-film systems for a particular application can
be achieved best by first representing the system as a mathematical model, and then
determining the necessary coefficients by running laboratory or pilot tests.
5/93
-------
BIOLOGICAL TREATMENT
TABLE 2
CONCENTRATION OF POLLUTANTS THAT MAKE PREBIOLOGICAL
OR PRELIMINARY TREATMENTS DESIRABLE
Pollutant or
System Condition
Suspended solids
Oil or grease
Toxic ions
Pb
Cu + Ni 4- CN
Cr6+ + Zn
Cr3*
PH
Alkalinity
Acidity
Organic load variation
Sulfides
Phenols
Ammonia
Dissolved salts
Temperature
Limiting Concentration
> 50-125 mg/1
flotation, lagooning
> 35-50 mg/1
<0.1 mg/1
^1 mg/1
<3 mg/1
< 10 mg/1
< 6, > 9
0.5 Ib alkalinity as
CaCO3/lb BOD removed
Free mineral acidity
> 2:1-4:1
> 100 mg/1
> 70 - 300 mg/1
> 1.6g/l
> 10-16 g/1
13 - 38°C in reactor
Kind of Pretreatment
Sedimentation
Skimming tank or separator
Precipitation or ion exchange
Neutralization
Neutralization for excessive
alkalinity
Neutralization
Equalization
Precipitation or stripping with
recovery
Extraction, adsorption, internal
dilution
Dilution, ion exchange, pH
adjustment, and stripping
Dilution, ion exchange
Cooling, steam addition
5/93
10
-------
BIOLOGICAL TREATMENT
The following models have been found to be reliable for designing biological
treatment systems for wastestreams containing priority pollutants (Cantor and Knox,
1985).
Activated Sludge:
FSJX
V -
Biological Tower and Rotating Biological Contactor:
fst
A = ———!
V
F
X
Si
se
UmaxandKB =
where: V = volume of aeration tank (ft3)
flow rate (fWday)
mixed liquor volatile solids (mg/1)
influent BOD, COD, TOC, or specific
organics (mg/1)
effluent BOD, COD, TOC, or specific
organics (mg/1)
biokinetic constants (day"1) max
A = surface area of biological tower or rotating
biological contactor (ft2)
The biokinetic constants are determined by conducting laboratory or pilot plant
studies. After the biokinetic constants are determined, the required volume of
aeration tank or the required surface area for a biological tower or rotating biological
contactor can be determined for any flow rate; influent concentration of BOD,
chemical oxygen demand (COD), TOC, or specific organic; and a required effluent
concentration of BOD, COD, TOC, or specific organic.
Technology Selection/Evaluation
Biological treatment has not been as widely used in hazardous waste site remediation
as activated carbon, filtration, and precipitation/flocculation. However, the process
is well established for treating a wide variety of organic contaminants. Kincannon
and Stove (as reported by Canter and Knox [1985]) have demonstrated the
effectiveness of activated sludge for treating priority pollutants. The results shown
in TABLE 3 indicate that activated sludge was effective for all groups of
contaminants tested except for halogenated hydrocarbons.
5/93
11
-------
BIOLOGICAL TREATMENT
TABLE 3
REMOVAL MECHANISMS OF TOXIC ORGANICS
Compound
Nitrogen Compounds
Acrylonitrile
Phenols
Phenol
2,4-DNP
2,4-DCP
PCP
Aromatics
1,2-DCB
1,3-DCB
Nitrobenzene
Benzene
Toluene
Ethylbenzene
Halogenated Hydrocarbons
Methylene Chloride
1,2-DCE
1,1,1-TCE
1,1,2,2-TCE
1,2-DCP
TCE
Chloroform
Carbon Tetrachloride
Oxygenated Compounds
Acrolein
Polycyclic Aromatics
Phenanthrene
Naphthalene
Phthalates
Bis(2-Ethylhexyl)
Other
Ethyl Acetate
Percent Treatment Achieved
Stripping
21.7
2.0
5.1
5.2
8.0
99.5
100.0
93.5
99.9
65.1
19.0
33.0
1.0
Sorption
0.02
0.19
91.7
0.50
0.83
1.19
1.38
Biological
99.9
99.9
99.3
95.2
97.3
78.2
97.8
97.9
94.9
94.6
33.8
78.8
64.9
99.9
98.2
98.6
76.9
98.8
5/93
12
-------
BIOLOGICAL TREATMENT
Although biological treatment can effectively treat a wide range of organics, it has
several drawbacks for hazardous waste site applications. The reliability of the
process can be adversely affected by "shock" loads of toxics. Start-up time can be
slow if the organisms need to be acclimated to the wastes and the detention time can
be long for complex wastes. However, the existence of cultures that have been
previously adapted to hazardous wastes can dramatically decrease start-up and
detention time.
There are a number of cleanup contractors who have used biological treatment as part
of a mobile treatment system. The high-purity oxygen treatment process is well
suited for mobile treatment applications because the high oxygen efficiency enables
use of smaller reactors, shorter detention time, and reduced power consumptions
relative to other activated sludge processes. A hazard associated with the high-purity
oxygen process is that the presence of low flash-point compounds can present a
potential fire hazard. However, the system is equipped with hydrocarbon analyzers
and control systems that deactivate the system when dangerously high concentrations
of volatiles are detected (Ghassemi, Yu, and Quinlivan, 1981). Loss of volatile
organics from other biological treatment processes can also pose some localized air
pollution and a health hazard to field personnel.
Rotating biological contactors also have advantages for hazardous waste site
treatment. The units are compact, they can handle large flow variations and high
organic shock loads, and they do not require use of aeration equipment.
Sludge produced in biological waste treatment may be a hazardous waste itself
because of the sorption and concentration of toxic and hazardous compounds
contained in the wastewater. If the sludge is hazardous, it must be disposed of in a
RCRA-approved manner. If it is not hazardous, disposal should conform with state
sludge disposal guidelines.
Costs
Costs for various sizes of activated sludge units are presented in TABLE 4. The
costs for these units assume a detention time of 3 hours and use of aeration basins,
air supply equipment, piping, and a blower building. Clarifier and recycle pumps are
not included. The basins are sized to the 50-percent recycle flow. The influent BOD
is assumed to be no greater than 130 ppm and the effluent BOD is assumed to be 40
ppm.
The operation and maintenance costs assume that the hydraulic head loss through the
aeration tank is negligible. Sludge wasting and pumping energy are not included.
Union Carbide manufactures a high-purity, oxygen-activated sludge system (UNOX)
suitable for mobile system applications. The mobile UNOX systems have a hydraulic
capacity of 5-40 gpm, are contained within 40-foot van trailers, and include an
external clarifier. The oxygen required is also supplied by Union Carbide. The
customer is expected to provide installation labor, operating manpower, analytical
support, and utilities. A typical installation requires 3-4 days.
5/93 13
-------
BIOLOGICAL TREATMENT
The mobile UNOX system can be either rented or purchased from the Union Carbide
Corporation. The estimated rental costs are as follows:
• $6,540 for the checkout and refurbishment of equipment to make it
operational
• $550/day for onsite service, including engineering consultation on program
planning and execution
• $9/day rental of equipment
• Transportation charges to get the equipment from the manufacturer to the site
of operation and back again.
The purchase price for the UNOX mobile unit is between $260,000 and $330,000
(Ghassemi, Yu, and Quinlivan, 1981; data updated using 1984 third quarter Marshall
Swift Index).
TABLE 4
GENERAL COST DATA FOR VARIOUS SIZES OF
ACTIVATED SLUDGE TREATMENT UNITS
Capacity (gpm)
70
140
350
694
Construction Costs ($)*
78,500
85,600
107,000
160,000
O&M Costs ($/year)*
4,300
6,400
10,000
15,700
* Updated from 1978 to 1984 dollars using third quarter Marshall and Swift Equipment Index.
Aerobic Biological Treatment
Aerobic biological treatment includes conventional activated sludge processes (FIGURE 1),
as well as newer modifications of these processes, such as sequential batch reactors, rotating
biological contactors, trickling filters, genetically engineered bacteria, and fixed-film reactors.
All of these systems offer effective treatment of aqueous wastestreams contaminated with low
levels of nonhalogenated organics and/or certain halogenated organics. These systems may
be combined with chemical or physical treatment systems to form multiple step treatment
trains capable of handling aqueous wastestreams with significant levels of inorganic and
organic contamination. This includes systems for removal of contaminants from soils using
flushing or washing techniques.
5/93
14
-------
ISl
VO
AERATION STAGE
CLARIFIER STAGE
WASTEWATER
FEED
AIR
AIR BUBBLES
FIXED AIR
BUBBLE ASSEMBLY
IMTTT
EFFLUENT
ACTIVATED SLUDGE RECYCLE
w
HN
o
s
2
n
>
r
i
FIGURE 1
ACTIVATED SLUDGE BIOLOGICAL TREATMENT
-------
BIOLOGICAL TREATMENT
Waste Types Handled
Aerobic biological treatment is suitable for aqueous wastestreams with low to
moderate levels of organic contamination. The degree of chlorination of the organics
will determine the efficiency and reliability of the biological treatment. Organics
with high degrees of chlorination may cause shock loading of the biomass, extended
biomass acclimation periods, and reduced treatment process efficiency and reliability.
Restriction Waste Characteristics
Biological systems require consistent, stable operating conditions, as abrupt changes
in wastestream characteristics can generate shock loading to the biomass. The
biomass can be vulnerable to highly elevated levels of heavy metals or halogenated
organics unless proper acclimation procedures are followed. Equally important is
maintenance of stable levels of key environmental parameters in the wastestream,
including dissolved oxygen, nutrients, pH, and alkalinity. Biological systems are
well suited for treatment of contaminated groundwater because groundwater
characteristics remain relatively stable.
Mobile System Considerations
Equipment required for aqueous waste treatment is relatively simple. Large tanks
equipped with aeration systems and agitators are used for the conventional activated
sludge biological treatment. The modified systems such as fixed film reactors and
trickling filter systems are more space efficient and transportable, and these systems
are currently offered as mobile units by several firms. Most systems require pumps
for circulation and aeration. The treated effluent from these units may need
additional treatment for clarification and removal of remaining organics and heavy
metals or for discharge to a municipal treatment system. Available mobile systems
require minimal labor when used with stable, consistent wastestreams. Fixed-film
or trickling filter systems offer significant advantages because of their
transportability, compact size, low operating costs, and high biomass growth surface
area relative to total volume. More conventional activated sludge systems require
sludge disposal for the accumulated biomass, and may be less well suited for mobile
systems. Sequential batch reactors can treat aqueous wastestreams with elevated
levels of contaminants, including certain halogenated organics. Pilot studies are
necessary to determine process feasibility. Careful monitoring of the biodegradation
process and water quality parameters will be necessary, particularly for more
concentrated wastestreams, thus requiring on site laboratory facilities.
Environmental Impacts
Settled sludge and/or excess biomass residues will need treatment or disposal and
may contain elevated levels of organics or heavy metals. Variation in wastestream
characteristics may generate shock loading and breakdown of the treatment train,
5/93 16
-------
BIOLOGICAL TREATMENT
necessitating preliminary monitoring. Undesirable odors may be generated, and it
may become necessary to drive off volatile organic compounds in the aeration basin.
Costs
The capital and operating costs depend on the specific process selected. Simple
treatment of low-level organic contamination can cost as little as 1/10 of a
comparable activated carbon system on a cost/gallon basis. More complicated waste-
streams may necessitate a more expensive, multiple step treatment train.
Commercial Applications
Polybac Corporation offers transportable systems for spill site decontamination using
microbial biodegradation.
Contact: Technical Services Coordinator
954 Mancon Boulevard
Allentown, PA 18103
215/264-8740
Detox, Inc., offers a series of portable, fixed-film aerobic reactors for a variety of
wastestreams.
Contact: Sales Manager
64 Marco Lane
Dayton, OH 45459
513/433-7394
OH Materials and Total Recovery offer transportable aeration tanks for aerobic
biodegradation.
Contact: Sales Manager Sales Manager
OH Materials Total Recovery
Fudley, OH Cleveland, OH
419/423-3526 215/644-6267
Groundwater Decontamination Systems offers transportable systems for aerobic
biological treatment of contaminated groundwater.
Contact: Sales Manager
Suite 210
140 Route 17 North
Paramus, NJ 07652
201/265-6727
5/93 17
-------
BIOLOGICAL TREATMENT
Anaerobic Digestion
Anaerobic digestion is biodegradation, a process that has the capability to handle high-
strength wastestreams which would not be efficiently treated by aerobic biodegradation
processes. Research has indicated that anaerobic treatment can break down halogenated
organics such as pesticides through reductive dehalogenation of carbon ring structures.
Additional advantages of anaerobic digestion processes include low production of biomass
sludges, low power requirements and operating costs, and the production of utilizable
methane gas. However, the reliability of anaerobic digesters is not ideal because of their
susceptibility to variation in the wastestream and the prolonged time periods required by the
slow rates of biodegradation. FIGURE 2 depicts a typical anaerobic digestion system.
Waste Types Handled
Anaerobic biological treatment is suitable for aqueous wastestreams with low to
moderate levels of organic contamination. Anaerobic systems can handle certain
halogenated organics better than aerobic systems, but the biodegradation process
(composed of two steps) can be prolonged.
Restrictive Waste Characteristics
As with aerobic systems, anaerobic systems are vulnerable to highly elevated levels
of heavy metals or halogenated organics unless proper acclimation procedures are
followed. Stable environmental conditions must be maintained in the wastestream,
including dissolved oxygen, nutrients, pH, and alkalinity. Changes in wastestream
characteristics may result in damage to the biomass and termination of the
biodegradation process.
Mobile System Considerations
Anaerobic digestors are available in single tank (standard rate) or two-tank (high
tank) systems. Volumetric flow through these systems is low and retention times are
long (10-30 days), which may seriously limit the application as mobile systems. Pilot
studies are necessary to determine process feasibility. Digestors also require careful
monitoring of operating parameters, necessitating an onsite laboratory. Sludge
disposal requirements are considerably less than for aerobic systems. Methane gas
is produced in significant quantities and must be used onsite or disposed of. Effluent
from the digestor will require additional treatment (FIGURES 3a, 3b & 3c).
Costs
Anaerobic digestors are traditionally used because they are more effective at
processing concentrated wastestreams (primarily biodegradable organic by products)
than comparable aerobic systems, and they have lower operating costs, produce less
biomass sludge, and produce utilizable methane gas. Costs for mobile units are not
available.
5/93 18
-------
SO
VO
INFLUENT
WASTEWATER
WITH
ORGANIC
MATERIAL
and C0
EFFLUENT
WASTEWATER
WITH
OXIDIZED
ORGANICS
o
s
2
n
>
i
FIGURE!
SCHEMATIC OF ROTATING BIOLOGICAL CONTACTOR
-------
I/I
VD
Gas removal
Sludge
inlets
K)
O
Digested
sludge
Gas storage
Scum Layer
Supernatant
outlets
Actively digesting
sludge
Sludge
outlets
FIGURE 3a
CONVENTIONAL, STANDARD-RATE, SINGLE-STAGE PROCESS
-------
Fixed
cover
CH4 + C02
^ Sludge
outlets
w
1—4
o
s
2
n
FIGURE 3b
HIGH-RATE, CONTINUOUS-FLOW STIRRED TANK
-------
LSI
Digester gas outlet
Fixed
cover
K)
to
Floating cover
Scum layer
First Stage
(completely mixed)
Second Stage
(stratified)
Supernatant
layer and
outlets
Sludge
outlet$
W
>-*
o
r
o
o
o
>
r
H
>
H
FIGURE 3c
TWO-STAGE TYPICAL ANAEROBIC DIGESTORS
-------
BIOLOGICAL TREATMENT
Commercial Applications
There are no commercial mobile units available at present.
Bioreclamation
General Description
Bioreclamation is a technique for treating zones of contamination by microbial
degradation. The basic concept involves altering environmental conditions to enhance
microbial catabolism or cometabolism of organic contaminants, resulting in the
breakdown and detoxification of those contaminants. The technology has been
developed rapidly over recent years, and bioreclamation appears to be one of the
most promising of the in-situ treatment techniques.
Considerable research conducted over the past several decades has confirmed that
microorganisms are capable of breaking down many of those organic compounds
considered to be environmental and health hazards at spill sites and uncontrolled
hazardous waste sites. Laboratory, pilot, and field studies have demonstrated that it
is feasible to use this capability of microorganisms in-situ to reclaim contaminated
soils and groundwater.
Microbial metabolic activity can be classified into three main categories: aerobic
respiration, in which oxygen is required as a terminal electron acceptor; anaerobic
respiration, in which sulfate or nitrate serves as a terminal electron acceptor; and
fermentation, in which the microorganism rids itself of excess electrons by exuding
reduced organic compounds.
The bioreclamation method that has been most developed and is most feasible for in-
situ treatment is one which relies on aerobic (oxygen-requiring) microbial processes.
This method involves optimizing environmental conditions by providing an oxygen
source and nutrients that are delivered to the subsurface through an injection well or
infiltration system to enhance microbial activity. Indigenous microorganisms can
generally be relied upon to degrade a wide range of compounds given proper
nutrients and sufficient oxygen. Specifically adapted or genetically manipulated
microorganisms are also available and may be added to the treatment zone.
Anaerobic microorganisms are also capable of degrading certain organic
contaminants. Methanogenic consortiums, groups of anaerobes that function under
very reducing conditions, are able to degrade halogenated aliphatics (e.g., PCE,
TCE) while aerobic organisms cannot. The potential for anaerobic degradation has
been demonstrated in numerous laboratory studies and in industrial waste treatment
processes that use anaerobic digesters or anaerobic waste lagoons as part of the
treatment process. Using anaerobic degradation as an in-situ reclamation approach
is theoretically feasible.
5/93 23
-------
BIOLOGICAL TREATMENT
Applications and Limitations
The feasibility of bioreclamation as an in-situ treatment technique is dictated by waste
and site characteristics. The factors that determine the applicability of a
bioreclamation approach are:
• Biodegradability of the organic contaminants
• Environmental factors that affect microbial activity
• Site hydrogeology.
Bioreclamation can be expected to reduce the concentration of only those organic
compounds which are amenable to biological degradation. These are compounds that
are either substrates for microbial growth and metabolism (the organism uses the
compound as a carbon and energy source) or are cometabolically broken down as the
microorganism uses another primary substrate as its carbon and energy source.
An extensive review of research on the relative biodegradabilities of environmental
pollutants can be found in Evaluation of Systems to Accelerate Stabilization of Waste
Piles (US EPA, 1985). Relative aerobic biodegradability of compounds can also be
estimated using laboratory data associated with oxygen requirements for
decomposition (i.e., 5-day and 21-day biological oxygen demand [BOD5, BOD21],
COD, and the ultimate oxygen demand [UOD].) TABLE 5 presents relative
biodegradabilities by adapted sludge cultures of various substances in terms of a
BOD5/COD ratio. A Property Estimation Methods (Lyman, Reehl, and Rosenblatt,
1982) provides additional information on methods of estimating biodegradability.
TABLE 6 summarizes organic groups subject to microbial metabolism by aerobic
respiration, anaerobic respiration, and fermentation. "Oxidation" indicates that the
compound is used as a primary substrate, and "co-oxidation" indicates that the
compound is cometabolized. These tables and estimation methods provide only a
general indication of degradability of compounds. In most instances, treatability
studies will be required to determine degradability of specific waste components.
For most compounds, the most rapid and complete degradation occurs aerobically.
There are some compounds, most notably the lower molecular weight halogenated
hydrocarbons, which will only degrade anaerobically. (However, recent research
conducted at EPA's Robert S. Kerr Laboratory has discovered degradation of TCE
in the presence of oxygen and methane gas [Wilson, 1984]).
It can be generalized that for the degradation of petroleum hydrocarbons, aromatics,
halogenated aromatics, polyaromatic hydrocarbons, phenols, halophenols, biphenyls,
organophosphates, and most pesticides and herbicides, aerobic bioreclamation
techniques are most suitable. For the degradation of halogenated lower molecular
weight hydrocarbons, such as the unsaturated alkyl halides PCE and TCE and the
5/93 24
-------
BIOLOGICAL TREATMENT
saturated alkyl halides 1,1,1-trichloroethane and trihalomethane, anaerobic
degradation under very reducing conditions appears to be the most feasible approach
in terms of the current understanding of microbial degradative capability. However,
aerobic degradation in the presence of methane gas appears promising for some low
molecular weight halogenated hydrocarbons.
The availability of the compound to the organism will also dictate its
biodegradability. Compounds with greater aqueous solubilities are generally more
available to degradative enzymes. For example, c/s-l,2-dichloroethylene is
preferentially degraded relative to frms-l,2-dichloroethylene. The most likely
explanation for this is because the cis configuration is more polar than trans and is
therefore more water soluble (Parsons et al., 1982). The use of surfactants can
increase the solubility and therefore the degradability of compounds (Ellis and Payne,
1984).
Environmental factors that affect microbial activity and population size will determine
the rate and extent of biodegradation. Hydrogeology will affect not only microbial
activity, but also the feasibility of in-situ treatment. These factors include:
• Appropriate levels of organic and inorganic nutrients trace elements
• Oxygen
• Redox potential
• pH
• Degree of water saturation
• Hydraulic conductivity of the soil
• Osmotic potential, including total dissolved solids
• Temperature
• Competition, including the presence of toxins and growth inhibitors
• Predators
• Types and concentrations of contaminants.
5/93 25
-------
BIOLOGICAL TREATMENT
TABLE 5
BODS/COD RATIOS FOR VARIOUS ORGANIC COMPOUNDS
Compound
Relatively Undegradable
Butane
Butylene
Carbon tetrachloride
Chloroform
1 ,4-Dioxene
Ethane
Heptane
Isobutane
Liquified natural gas
Liquified petroleum gas
Methane
Methyl bromide
Methylchloride
Monochlorodifluoromethane
Ratio
-0
-0
-0
-0
-0
-0
-0
-0
-0
-0
-0
-0
-0
-0
Compound
Nitrobenzene
Propane
Propylene
Propylene oxide
Tetrachloroethylene
Tetrahydronaphthalene
1-Pentene
Ethylene dichloride
1-Octene
Morpholine
Ethylenediaminetetraacetic acid
Triethanolamine
o-Xylene
m-Xylene
Ethylbenzene
Ratio
-0
-0
-0
-0
-0
-0
< 0.002
0.002
> 0.003
< 0.004
0.005
< 0.006
< 0.008
< 0.008
< 0.009
TABLE 5 CONT.
BODj/COD RATIOS FOR VARIOUS ORGANIC COMPOUNDS
Compound
Moderately Degradable
Ethyl ether
Sodium alkybenzenesulfonates
Mineral spirits
Cyclohexanol
Acrylonitrile
Nonanol
Undecanol
Methylethylpyridine
1-Hexene
Methyl isobutyl ketone
Diethanolamine
Formic acid
Ratio
0.012
-0.017
-0.02
0.03
0.031
> 0.033
< 0.04
0.04-0.75
< 0.044
< 0.044
< 0.049
0.05
Compound
Styrene
Heptanol
sec-Butyl acetate
n-Butyl acetate
Methyl alcohol
Acetonitrile
Ethylene glycol
Ethylene glycol monoethyl ether
Sodium cyanide
Linear alcohols (12-15 carbons)
Allyl alcohol
Dodencanol
Ratio
> 0.06
< 0.07
0.07-0.23
0.07-0.24
0.07-0.73
0.079
0.081
< 0.09
< 0.09
> 0.09
0.091
0.097
5/93
26
-------
BIOLOGICAL TREATMENT
TABLE 5 CONT.
BOD5/COD RATIOS FOR VARIOUS ORGANIC COMPOUNDS
Compound
Relatively Degradable
Valeraldehyde
n-Decyl alcohol
p-Xylene
Urea
Toluene
Potassium cyanide
Isopropyl acetate
Amyl acetate
Chlorobenzene
Jet fuels (various)
Kerosene
Monoisopropanolamine
Gas oil (cracked)
Gasolines (various)
Furfural
2-Ethyl-3-propylacrolein
Methylethylpyridine
Vinyl acetate
Diethylene glycol
monomethylether
Naphthalene (molten)
Dibutyl phthalate
Hexanol
Soybean oil
Paraformaldehyde
n-Propyl alcohol
Methylmethacrylate
Acrylic acid
Sodium alkyl sulfates
Triethylene glycol
Acetic acid
Acetic anhydride
Ethylenediamine
Formaldehyde solution
Ethyl acetate
Octanol
Ratio
< 0.10
> 0.10
< 0.11
0.11
< 0.12
0.12
< 0.13
0.13-0.34
0.15
-0.15
-0.15
< 0.02
-0.02
-0.02
0.17-0.46
< 0.19
< 0.20
< 0.20
< 0.20
< 0.20
0.20
-0.20
-0.20
0.20
0.20-0.63
< 0.24
0.26
-0.30
0.31
0.31-0.37
> 0.32
0.26
0.36
< 0.36
0.37
Compound
Sorbitol
Benzene
n-Butyl alcohol
Propionaldehyde
n-Butyraldehyde
Range oil
Glycerine
Adeponitrile
Ethyleneimine
Monoethanolamine
Pyridine
Dimethylformamide
Dextrose solution
Corn syrup
Maleic anhydride
Propionic acid
Acetone
Aniline
Isopropyl alcohol
n-Amyl alcohol
Isoamyl alcohol
Cresols
Crotonaldehyde
Phthalic anhydride
Benzaldehyde
Isobutyl alcohol
2 ,4-Dichlorophenol
Tallow
Phenol
Benzoic acid
Carbolic acid
Methylethyl ketone
Benzoyl Chloride
Hydrazine
Oxalic acid
Ratio
< 0.38
< 0.39
0.42-0.74
< 0.43
< 0.43
-0.15
< 0.16
0.17
0.46
0.46
0.46-0.58
0.48
0.50
-0.50
> 0.51
0.52
0.55
0.56
0.56
0.57
0.57
0.57-0.68
< 0.58
0.58
0.62
0.63
0.78
-0.80
0.81
0.84
0.84
0.88
0.94
1.0
1.1
5/93
27
-------
BIOLOGICAL TREATMENT
TABLE 6
SUMMARY OF ORGANIC GROUPS SUBJECT TO BIODEGRADATION
Substrate Compounds
Straight Chain Alkanes
Branched Alkanes
Saturated Alkyl Halides
Unsaturated Alkyl Halines
Esters, Glycols, Epoxides
Alcohols
Aldehydes, Ketones
Carboxylic Acids
Amides
Esters
Nitriles
Amines
Phthalate Esters
Nitrosamines
Thiols
Cyclic Alkanes
Unhalogenated Aromatics
Halogenated Aromatics
Simple Aromatic Nitro
Compounds
Aromatic Nitro
Compounds with
Other Functional
Groups
Phenols
Halogenated Side Chain
Aromatics
Fused Ring Hydroxy
Compounds
Nitrophenols
Halophenols
Phenols-Dihydrides, Poly-
hydrides
Two- and Three-Ring
Fused Polycyclic
Hydrocarbons
Biphenyls
Chlorinated Biphenyls
Four-Ring Fused Polycyclic
Hydrocarbons
Fused Polycyclic Hydro-
carbons
Organophosphates
Pesticides and Herbicides
Respiration
Aerobic
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
4-
+
Anaerobic
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
Fermination
+
+
+
+
+
+
Oxidation
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
Co-oxidation
+
+
+
+
+
+
+
+
5/93
28
-------
BIOLOGICAL TREATMENT
Microorganisms, like all living organisms, require specific inorganic nutrients (e.g.,
nitrogen, phosphate-phosphorus, and trace metals), and a carbon and energy source
to survive. Many organic contaminants provide the carbon and energy and thus serve
as primary substrates. If the organic compound that is the target of the
bioreclamation is only degraded cometabolically, a primary substrate must be
available. Aerobes need oxygen, nitrate respirers need nitrate, and sulfate respirers
need sulfate. Various anaerobic populations require specific reducing conditions.
Optimum microbial activity for bioreclamation purposes occurs within a pH range of
6.0 to 8.0, with slightly alkaline conditions being more favorable.
The temperature range for optimal organism growth in aerobic biological wastewater
treatment processes has been found to range from 20° to 37°C (68° to 99°F).
According to the "Q-10" rule, for every 10°C decrease in temperature in a specific
system, enzyme activity is halved. FIGURE 4 illustrates typical groundwater
temperatures throughout the United States. Although microbial populations in colder
waters are adapted to lower temperatures, biodegradation rates can be expected to be
much slower than at higher temperatures. It may not be feasible to attempt the
bioreclamation approach in the extreme north.
52°
67" 72s
FIGURE 4
TYPICAL GROUNDWATER TEMPERATURES (*F)
AT 100 FT. DEPTH IN THE UNITED STATES
5/93
29
-------
BIOLOGICAL TREATMENT
Concentrations of inorganic and/or organic contaminants could be so high as to be
toxic to the microbial populations. TABLE 7 lists concentrations at which certain
compounds have been found to be toxic in industrial waste treatment.
Microorganisms present in the subsurface may be more tolerant to high
concentrations of these compounds. This determination must be made on a case-by-
case basis. Conversely, a situation may prevail in which the contaminant
concentrations are so low (<0.1 mg/1) that the assimilative processes of the
microorganisms are sometimes not stimulated. Thus, adaptation to the particular
substrate will not occur and the substrate will not be degraded (SCS Engineers,
1979). It is also possible that even if the contaminant is present in acceptable
concentrations, if there is another "preferred" carbon source available, the
microorganisms will catabolize it preferentially.
It is feasible to manipulate some of these factors insitu to optimize environmental
conditions. Nutrients and oxygen (or NO3") can be added to the subsurface. It may
be feasible in some cases to enhance reducing conditions, thereby lowering the redox
potential. The pH can be adjusted with the addition of dilute acids or bases. Water
could be pumped into an arid zone. Bioreclamation could be preceded by other
treatments that could reduce toxic concentrations to a tolerable level. Even raising
the temperature of a contaminated zone by pumping in heated water or recirculating
groundwater through a surface heating unit may be feasible under conditions of low
groundwater flow. This was done at a bioreclamation site in West Germany to
increase the groundwater temperature by 10°C (see TABLE 8) (Stief, 1984).
There are some factors that cannot be corrected, such as the presence of predators,
competition between microbial populations, or the salinity of groundwater. This
points to one of the advantages of relying on indigenous microorganisms rather than
added microorganisms to degrade wastes. Although the added specialized
microorganisms may have a superior degradation capability as developed in the
laboratory or enriched in a surface biological reactor, they may not be able to survive
subsurface conditions (e.g., salinity, light intensity, temperature, and type of
predators). However, through countless generations of evolution, natural populations
have developed that are ideally suited for survival and proliferation in that
environment. This is particularly true of uncontrolled hazardous waste sites where
microorganisms have been exposed to the wastes for years or even decades.
However, use of specialized microorganisms can be expected to have the greatest
application at spill sites where the exposure time has not been long enough for a
substantial adapted indigenous population to evolve.
5/93 30
-------
BIOLOGICAL TREATMENT
TABLE 7
PROBLEM CONCENTRATIONS OF SELECTED CHEMICALS
Chemical
n-Butanol
sec-Butanol
t-Butanol
Allyl alcohol
2-Ethyl-l-hexanol
Formaldehyde
Crotonaldehyde
Acrolein
Acetone
Methyl isobutyl ketone
Isophorone
Diethylamine
Ethylenediamine
Acrylonitrile
2-Methyl-5-ethylpyridine
N,N-dimethylaniline
phenol
Ethyl benzene
Ethyl acrylate
Sodium acrylate
Dodecane
Dextrose
Ethyl acetate
Ethylene glycol
Diethylene glycol
Tetraline
Kerosene
Cobalt chloride
Problem Concentration (mg/1)
Substrate(1)
..
..
> 1000
500-1000
200
> 1000
> 1000
> 1000
> 1000
> 1000
> 1000
> 1000
600-1000
> 1000
> 1000
> 1000
> 1000
> 1000
«
~
Nonsubstrate(2)
> 1000
> 1000
> 1000
> 1000
50-100
50-100
> 1000
> 1000
300-1000
100-300
100
100
300-1000
300-600
> 500
> 1000
> 900
> 1000
> 500
> 1000
(1) Substrate limiting represents the condition in which the subject compound is the sole
carbon and energy source.
® Nonsubstrate limiting represents the condition in which other carbon and energy sources
are present.
Source: SCS Engineers, 1979
5/93
31
-------
UJ
to
TABLE 8
SITE RECLAMATIONS USING BIODEGRADATION, INDIGENOUS MICROORGANISMS
Location
Ambler, PA
1972
Millville, NJ
1976
LaGrange, OR
1982
Biocraft Labs
Waldwick, NJ
1981
Karlsruhe
West Germany
1982
Frankenthal
West Germany
Granger, IN
1984
Kelly Air Force
Base. TX
1985
Contaminant
Gasoline spill
Gasoline spill
Gasoline leak
Methylene chloride,
butanol, dimethyl
online, acetone
Petroleum products,
cyanide
Aromatic and
aliphatic
hydrocarbons
including benzene,
styrene, toluene,
xylene, and
naphthalene
Gasoline leak
Jet fuel
hydrocarbons,
halogenated alkanes
and aromatics, heavy
metals
Waste Site
Characteristics
Soil and groundwater
contamination in a
dolomite aquifer
Soil and groundwater
contamination in a sandy
aquifer
Soil and groundwater
contamination in a
shallow, highly permeable
aquifer
Soil and groundwater
contamination in a layer of
glacial fill
Soil and groundwater
contamination in a
sandy/gravelly aquifer
Soil and groundwater
contamination in a sandy,
high permeability aquifer
Soil and groundwater
contamination in a sandy
aquifer
Hazardous waste disposal
site; soil and groundwater
contamination in clayey,
low permeability aquifer
Treatment
Physical recovery followed by in-situ treat-
ment. Nutrient solution delivered; air
sparged through wells. Producing wells
controlled groundwater flow.
Physical recovery followed by in-situ treat-
ment. Nutrient solution delivered; air
sparged through wells. Producing wells
controlled groundwater flow.
Physical recovery followed by in-situ treat-
ment. Nutrient addition; groundwater
recycled through site. Air supplied at
bottom of injection trench with diffusers.
Physical recovery followed by surface bio-
logical treatment with indigenous micro-
organism; reinjection and in-situ treatment
using aeration wells. Producing wells
controlled groundwater flow.
Groundwater pumped to surface, treated
with ozone, then reinfiltrated.
Physical recovery followed by in-situ treat-
ment. Nitrate respiration enhanced by the
addition of nitrate, recirculated flushing
water stripped and filtered before rein-
jection. Water temperature increased 10°C.
Physical recovery followed by in-situ
treatment. Hydrogen peroxide as oxygen
source and nutrients added in-line to
recycled water.
In-situ treatment planned. Nutrients and
hydrogen peroxide will be added to recycled
groundwater.
Comments
No gasoline left in aquifer
10 months after treatment;
estimated from 744 to 944
barrels degraded
No free product detected at
end of program; phenol
concentrations reduced to
acceptable levels
System operated one year,
after which no free product
detected
Concentrations reduced from
100 to 700 mg/1 down to 0. 1
mg/1 or less in groundwater
after two year program
Drinking water quality
produced
In 3 months aromatics gone
and aliphatics reduced to 1/4
initial concentrations
Program evaluation not yet
available
Treatment to commence
Spring of 1985
Reference
Raymond,
Jamison, and
Hudson, 1976
Raymond et al.,
1978
Minugh et al.,
1983
Jhaveri and
Mazzacca, 1984
Nageietal., 1982
in Lee and Ward,
1984
Stief, 1984
API, Washington,
DC., personal
communication
Wetzel, Henry,
and Spooner, 1985
-------
BIOLOGICAL TREATMENT
Significant and active microbial populations have been found in the subsurface.
Many types of bacteria have been isolated from subsurface soils and groundwater,
and a considerable amount of research has recently been conducted to enumerate and
characterize subsurface populations (e.g., Hirsch and Rades-Rohkohl, 1983; White
et al., 1983; Ghiorse and Balkwill, 1983; Wilson et al., 1983; Ehrlich et al., 1983,
Ventullo and Larson, 1983; and Harvey, Smith, and George, 1984).
Research confirms that substantial adapted populations do exist in contaminated zones
and that bacterial numbers are elevated in contaminated zones relative to
uncontaminated zones (i.e., the organic contaminants are being metabolized, leading
to an increase in bacterial biomass). For example, in one study, significant bacterial
populations were found in groundwater contaminated with gasoline, fuel oil, and
other petroleum products (Litchfield and Clark, 1973). Groundwater containing less
than 10 ppm of these hydrocarbons generally had populations of less than 103
organisms/ml, whereas groundwater with greater than 10 ppm hydrocarbons
contained populations on the order of 106 organisms/ml. An investigation of a
hazardous waste site contaminated with high concentrations of jet fuel hydrocarbons,
industrial solvents, and heavy metals revealed bacterial numbers on the order of 107
cells/wet gram sample in core samples taken from the upper unsaturated zone and the
saturated zone (Wetzel, Henry, and Spooner, 1985). A biodegradation study
conducted with subsurface soil and groundwater from this site revealed that both
aerobic and anaerobic populations were present that were capable of degrading the
organic contaminants.
Even if substantial, active microbial populations are present, the wastes are
biodegradable, and there are parameters that can be altered to optimize
biodegradation insitu, bioreclamation will not be feasible if the hydrogeology of the
site is not suitable. The hydraulic conductivity must be great enough and the
residence time short enough so that added substances, oxygen, and nutrients are not
"used up" before reaching the distant portions of the treatment zone. Sandy and
other highly permeable sites will be far easier to treat than sites containing clayey
soils.
There is also the possibility that added substances may react with the soil
components. Oxidizing the subsurface could result in the precipitation of iron and
manganese oxides and hydroxides. If precipitation is extensive, the delivery system
and possibly even the aquifer could become clogged. The in-situ bioreclamation of
a site near Granger, Indiana, developed problems with precipitation and clogging of
the aquifer (TABLE 9). Addition of phosphates could result in the precipitation of
calcium and iron phosphates. If calcium concentrations are high, the added
phosphate can be tied up by the calcium and would therefore not be available to the
microorganisms.
5/93 33
-------
LA
TABLE 9
EXAMPLES OF BIOLOGICAL RENOVATION AT CONTAMINATED SITES
Waste Site
Contamination
Styrene
Atrazine
Sludge con-
taining Tri-
chlorophenate
Petroleum
Distillate
Acrylonitrile
Formaldehyde
Ortho - Chloro-
phenol
Concentration
(ppm)
25
Saturated
300
12,000
1,000
1,400
15,000
:. , ;Wa^tfe.::&;;- ;•;;. < ::-
Characteristics
Railroad tankcar spill, area
soils contaminated to a
depth of 8 inches
50-acre field
Sludge spread on soil to a
depth of 6 inches
Spill covering 4 acres at an
oil tank farm
Soil and groundwater
contamination
Soil and groundwater
contamination
Soil and groundwater
contamination
Biological
Agent
BI-CHEM SUS-8
BI-CHEM-PBO-6
BI-CHEM-GEC-1
BI-CHEM-SUS-8
PHENOBAC
PHENOBAC
MUTANT
BACTERIA
Treatment Time
(days)
21
28
21
90
22
274
Residual
Concentration
(ppm)
less than 1
less than 1
less than 1
less than 1
less than 1
less than 1
w
M
I
NH
g
Source: US EPA, 1982a
-------
BIOLOGICAL TREATMENT
Heavy metals, bound in the soil matrix, could be mobilized into the groundwater.
In reduced conditions, especially when there is ample organic carbon available,
metals are likely to be bound in the soil as organic/metal chelates and as sulfides.
When oxidized, the metal cations could coprecipitate with ferric hydroxide and/or
precipitate in calcium/phosphate complexes. If iron and phosphate precipitation does
not occur to a significant extent, the soluble metallic cations will remain in the
aqueous phase. The soils may also plug as a result of excess biological growth.
Design Considerations
Biological treatment at contaminated sites encompasses both in-situ treatment
approaches and treatment approaches involving groundwater withdrawal and treatment
in biological reactors on the surface. This section addresses in-situ treatment and the
combined use of in-situ and aboveground treatment.
Aerobic Bioreclamation
The first site remediation to treat hydrocarbon contamination insitu was conducted by
Raymond, Jamison, and coworkers at Suntech in the early 1970s. The first treatment
approaches involved stimulating the indigenous microflora through the delivery of nutrients
and air to the subsurface. Considerable developments have been made since the early 1970s,
and many different treatment approaches have been used successfully to enhance
biodegradation in contaminated zones. The indigenous microflora have been used in some
site cleanups to degrade wastes. Specialized microorganisms, either adapted strains or
genetically altered strains, have been used at other site remediations. Air was used in the
earlier site remediations to provide oxygen. Hydrogen peroxide or possibly ozone now
appear to be feasible alternatives to air or pure oxygen as an oxygen source. The earlier
applications involved gasoline spills (Raymond, Jamison, and Hudson, 1976). Biological
degradation is now being tested at a hazardous waste disposal site that contains a complex
range of organics (Wetzel, Henry, and Spooner, 1985). TABLE 8 lists site reclamations that
have involved stimulating the indigenous microflora. TABLE 9 lists site reclamations in
which specialized microorganisms were used.
Oxygen Supply
Oxygen can be provided to the subsurface through the use of air, pure oxygen,
hydrogen peroxide, or possibly ozone. TABLE 10 summarizes the advantages and
disadvantages of the oxygen supply alternatives.
Air can be added to extracted groundwater before reinjection, or it can be injected
directly into the aquifer. The first method, in-line aeration, involves adding air into
the pipeline and mixing it with a static mixer (FIGURE 5). This can provide a
maximum of approximately 10 mg/1 O2.
5/93 35
-------
BIOLOGICAL TREATMENT
TABLE 10
OXYGEN SUPPLY ALTERNATIVES
Substance
Air
Oxygen-
Enriched Air
or Pure
Oxygen
Hydrogen
Peroxide
Ozone
Application
Method
In-line
. In-situ wells
In-line
In-situ wells
In-line
In-line
Advantage
• Most economical
• Constant supply of
oxygen possible
• Provides considerably
higher 02 solubility
than does aeration
• Constant supply of
oxygen possible
• Moderate cost
• Intimate mixing with
groundwater
• Greater O2 concent-
rations can be
supplied to the sub-
surface (100 mg/1)
H2O2 provides 50
mg/1 O2
• Helps to keep wells
free of heavy
biogrowth
• Chemical oxidation
will occur, rendering
compounds more bio-
degradable
Disadvantages
• Not practical except
for trace
contamination < 10
mg/1 COD
• Wells subject to
blowout
• Not practical except
for low levels of
contamination < 25
mg/1 COD
• Very expensive
• Wells subject to
blowout
• H2O2 decomposes
rapidly upon contact
with soil, and
oxygen may bubble
out prematurely
unless properly
stabilized
• Ozone generation is
expensive
• Toxic to micro-
organisms except at
low concentrations
• May require
additional aeration
5/93
36
-------
BIOLOGICAL TREATMENT
Air
Flow
FIGURES
CONFIGURATION OF STATIC MIXER
Source: US EPA, 1985
This concentration is sufficient only for degradation of about 5 mg/1 hydrocarbons,
and would therefore provide an inadequate oxygen supply. A pressurized line and
the use of pure oxygen can increase oxygen concentrations.
The equilibrium oxygen concentration in water increases with increased air pressure
according to Henry's Law (Sawyer and McCarty, 1967):
5/93
37
-------
BIOLOGICAL TREATMENT
where: CL = PHk
CL = concentration of oxygen in liquid (mg/1)
= volume fraction (0.21 for O2 in air)
P = air pressure (atm)
Hk = Henry's Law Constant for oxygen.
The value of Henry's Law constant is 43.8 mg/1-atmosphere at 68°F (20°C).
Pressure increases with groundwater depth at the rate of 0.0294 atmospheres per foot.
The use of in-situ aeration wells (FIGURE 6) is a more suitable method for injecting
air into contaminated leachate plumes. A bank of aeration wells can be installed to
provide a zone of continuous aeration through which the contaminated groundwater
would flow. Oxygen saturation conditions can be maintained for degrading organics
during the residence time of groundwater flow through the aerated zone. The
required time for aeration can be derived from bench-scale studies. Residence time
(t,) through the aerated zone can be calculated from Darcy's equation (Freeze and
Cherry, 1979) using groundwater elevations (i.e., head) and hydraulic conductivity
as follows:
t, = (La)2/K(hrh2)
where
t,. = residence time (sec)
K = hydraulic conductivity (ft/sec)
La = length of aerated zone (ft)
h! = groundwater elevation at beginning of aerated zone (ft)
h2 = groundwater elevation at end of aerated zone (ft).
In the design of an in-situ aeration well zone system, the zone must be wide enough
to allow the total plume to pass through. The flow of air must be sufficient to give
a substantial radius of aeration but small enough to not cause an air barrier to the
flow of groundwater.
5/93 38
-------
BIOLOGICAL TREATMENT
Plane View
iont of Aeration
Surf«c» Contour*.
Direction of Groundwittr Flow
Cross-sectional
View
. Air Injection Wells
• e •
•
•
• •
W
. Aarated Zone
FIGURE 6
POSSIBLE CONFIGURATION OF IN-SITU AERATION WELL BANK
Source: US EPA, 1985
5/93
39
-------
BIOLOGICAL TREATMENT
Various methods can be used to inject air or pure oxygen. Air has been sparged into
wells using diffusers. For example, Raymond et al. (1975) sparged air into wells
using diffusers attached to paint sprayer compressors that could deliver approximately
2.5 cubic feet per minute. They were fitted with steel end plates and fittings to
accommodate a polyethylene air line and a nylon rope and were suspended into the
wells.
A blower can also be used to provide the flow rate and pressure for aeration. At the
groundwater bioreclamation project in Waldwick, New Jersey, 5 pounds per square
inch pressure is maintained in nine 10-foot aeration wells, each with an air flow of
5 cubic feet per minute (Groundwater Decontamination Systems, Inc., 1983).
Microdispersion of air in water using colloidal gas aprons (CGA) creates bubbles
25-50 micrometers in diameter. This is a newly developed method which holds great
promise as a means of introducing oxygen to the subsurface (Michelsen, Wallis, and
Sebba, 1984). With selected surfactants, dispersions of CGAs can be generated
containing 65-percent air by volume.
Oxygenation systems, either in-line or in-situ can also be installed to supply oxygen
to the bioreclamation process. Their advantage over conventional aeration systems
is that higher oxygen solubilities and, hence, more efficient oxygen transfer to the
microorganisms can be attained. Solubilities of oxygen in various liquids are 4-5
times higher under pure oxygen systems than with conventional aeration. Therefore,
in-line injection of pure oxygen will provide sufficient dissolved oxygen to degrade
20-30 mg/1 of organic material, assuming 50-percent cell conversion. The higher
oxygen solubilities may provide some flexibility in the design of cell banks, especially
at greater pressures, because the oxygen may not be used up immediately, as with
aeration.
Hydrogen peroxide (H2O2) as an oxygen source has been used successfully at the
cleanup of several spill sites (Brubaker, G.R., FMC Aquifer Remediation Systems,
Princeton, New Jersey, personal communication, 1985). Advantages of hydrogen
peroxide include:
• Greater oxygen concentrations can be delivered to the subsurface. 100 mg/1
H2O2 provides 50 mg/1 O2.
• Less equipment is required to oxygenate the subsurface. Hydrogen peroxide
can be added in-line along with the nutrient solution. Aeration wells are not
necessary.
• Hydrogen peroxide keeps the well free of heavy biogrowth. Microbial
growth and subsequent clogging are sometimes a problem in air injection
systems (Yaniga, Smith, and Raymond, 1984).
5/93 40
-------
BIOLOGICAL TREATMENT
Hydrogen peroxide is cytotoxic, but research has demonstrated that it can be added
to acclimated cultures at up to 1,000 ppm without toxic effects (Texas Research
Institute, 1982). The remediation at Granger, Indiana, involved adding an initial
concentration of 100 ppm and increasing it to 500 ppm over the course of the
treatment (API, Washington, DC, personal communication, 1985).
Hydrogen peroxide decomposes to oxygen and water (H2O2-»O2 + H2O). In the
subsurface, hydrogen peroxide decomposition is catalyzed by chemical and biological
factors. There has been some concern that decomposition could occur so rapidly that
oxygen would bubble out near the site of injection and no oxygen would be made
available to the distant portions of the treatment zone. Research has shown that high
concentrations of phosphates (10 mg/1) can stabilize peroxide for prolonged periods
of time in the presence of ferric chloride, an aggressive catalyst (Texas Research
Institute, 1982). However, there are problems associated with adding such high
phosphate concentrations to the subsurface. One problem is precipitation. One
company claims to have developed specially stabilized hydrogen peroxide products
for aquifer remediation. However, process performance information on these
products is not available.
Ozone is used for disinfection and chemical oxidation of organics in water and
wastewater treatment. In commercially available ozone-from-air generators, ozone
is produced at a concentration of 1-2 percent in air (Nezgod, W., PCI Ozone
Corporation, West Caldwell, New Jersey, personal communication, 1983). In
bioreclamation, this ozone-in-air mixture could be contacted with pumped leachate
using in-line injection and static mixing or using a bubble contact tank. A dosage of
1-3 mg/1 of ozone can be used to attain chemical oxidation (Nezgod, W., PCI Ozone
Corporation, West Caldwell, New Jersey, personal communication, 1983). However,
German research on ozone pretreatment of contaminated drinking waters indicates
that the maximum ozone dosage should not be greater than 1 mg/1 of ozone per mg/1
total organic carbon; higher concentrations may cause deleterious effects to
microorganisms (Rice, R.G., Rip G., Rice, Inc., Ashton, Maryland, personal
communication, 1983). At many sites, this may limit the use of ozone as a
pretreatment method to oxidize refractory organics, making them more amenable to
biological oxidation.
A petroleum products spill in Karlsruhle, Germany, was cleaned up in-situ using
ozone as an oxygen source for biological degradation (Nagel et al., 1982, in Lee and
Ward, 1984). The groundwater was pumped out, treated with ozone, and
recirculated. Approximately 1 gram of ozone per gram of dissolved organic carbon
was added to the groundwater and was allowed a contact time of 4 minutes in the
aboveground reactor. This increased the oxygen content to 9 mg/1 with a residual of
0.1-0.2 grams of ozone per cubic meter in the treated water.
5/93 41
-------
BIOLOGICAL TREATMENT
Nutrients
Nitrogen and phosphate are the nutrients most frequently present in limiting
concentrations in soils. Other nutrients required for microbial metabolism include
potassium, magnesium, calcium, sulfur, sodium, manganese, iron, and trace metals.
Many of these nutrients may already be present in the aquifer in sufficient quantities
and need not be supplemented.
The optimum nutrient mix can be determined by laboratory growth studies and from
geochemical evaluations of the site. Caution must be exercised in evaluating
microbial needs based on soil and groundwater chemical analysis. Chemical analysis
does not necessarily indicate what is available to the microorganisms. In some cases
generalizations can be made (e.g., if calcium is present at 200 mg/1 [a very high
concentration], it is likely that calcium supplementation is unnecessary).
The form of nutrients may or may not be critical in terms of microbial requirements,
depending on the site. Studies have shown that forms of nitrogen and phosphate were
not critical for microorganisms (Jamison, Raymond, and Hudson, 1976). However,
it has been recommended that an ammonia-nitrogen source is preferable to a nitrate-
nitrogen source because ammonia-nitrogen is more easily assimilated by
microorganisms (FMC, 1985). Nitrate is also a pollutant limited to 10 mg/1 in
drinking water.
The site geochemistry may be a critical factor in determining the form of nutrients,
as well as the added concentrations. For example, use of diammonium phosphate
could result in excessive precipitation (Jamison, Raymond, and Hudson, 1976), and
nutrient solution containing sodium could cause dispersion of the clays, thereby
reducing permeability (Anderson, D., K.W. Brown and Associates, Inc., College
Station, Texas, personal communication, 1985). Where calcium is high, it is likely
to lead to the precipitation of added phosphate, rendering it unavailable to microbial
metabolism. If a site is likely to encounter problems with precipitation, iron and
manganese addition may not be desirable. If the total dissolved solids content in the
water is extremely high, it may be desirable to add as little extra salts as possible.
The compositions of some basal salts media are given in TABLES 11 and 12. Only
phosphate and nitrogen had to be added to a site in Ambler, Pennsylvania. Bulk
quantities of ammonium sulfate [(NH4)2SO4)], disodium phosphate (NajHPO^, and
monosodium phosphate (NaH2PO4) were mixed in a 2,200-gallon tank truck and
added to the groundwater in the form of a 30-percent concentration in water that was
metered into the injection wells (Raymond, Jamison, and Hudson, 1976). Phosphate
concentrations in injection wells varied from 200 to 5,800 mg/1 throughout the site
cleanup. Phosphate concentrations in all wells were determined weekly and injection
rates were adjusted accordingly.
5/93 42
-------
BIOLOGICAL TREATMENT
TABLE 11
COMPOSITION OF BASAL SALTS MEDIA
Salt Type
KH2PO4
Na2HOP4
(NH4)N03
MgSO47H2O
Na2CO3
CaCl22H2O
MnSO24H2O
FeSO47H2O
Concentration (mg/1)
400
600
10
200
100
10
20
5
Source: Jamison, Raymond, and Hudson, 1976
TABLE 12
BASAL SALT MEDIUM USED BY CDS, INC.
Salt
Concentration (mg/1)
NH4C1
KH2PO4
K2HPO4
MgS04
Na2CO3
CaCl2
MnSO4
FeSO4
500
270
410
1.4
9
0.9
1.8
0.45
Groundwater Decontamination Systems, Inc., 1983
CDS, Inc., used the basal salt medium listed in TABLE 12 in the combined
surface//n-5/m treatment system at the Biocraft site (Jhaveri and Mazzacca, 1984).
The nutrient solution used at the Granger, Indiana, site was composed of ammonium
nitrate and disodium phosphate (FMC, 1985).
5/93
43
-------
BIOLOGICAL TREATMENT
An organic carbon source, such as citrate or glucose, could be added if the compound
of interest is only degraded cometabolically and a primary carbon source is required.
Such additions could also be made when low levels of contaminants are present and
are not sufficient to sustain an active microbial population. Citrate, or another
chelator such as EDTA, could be added to hold metals in solution if water is alkaline,
a condition under which metals may precipitate. Citrate, however, will be
preferentially degraded relative to other organics, and could slow the degradation of
contaminants. Addition of low concentrations of a source of amino acids, such as
peptone or yeast extract, could promote biodegradation. However, high
concentrations of these compounds could inhibit degradation of contaminants because
of preferential degradation.
Design of Delivery and Recovery Systems
One of the major factors determining success of an in-situ treatment system is to
ensure that the injection and recovery systems are designed to accomplish the
following:
• Provide adequate contact between treatment agents and contaminated soil or
groundwater
• Provide hydrologic control of treatment agents and contaminants to prevent
their migration beyond the treatment area
• Provide for complete recovery of spent treatment solutions and/or
contaminants where necessary.
A number of design alternatives are available for delivering nutrients and oxygen to
the subsurface and for collecting and containing the groundwater. These methods can
generally be categorized as gravity flow or forced methods. Most of the systems that
have been used for bioreclamation have involved the use of subsurface drains (gravity
system), injection wells, and extraction wells. Some examples of delivery and
recovery systems are described below.
FIGURE 7 illustrates a hypothetical configuration in which groundwater is extracted
downgradient of the zone of contamination and reinjected upgradient. In-situ aeration
supplies oxygen directly to the contaminant plume, while nutrients and oxygen are
added in-line by way of mixing tanks. Treated water is infiltrated through
contaminated soil to flush contaminants from the soil. Extraction and injection wells
can be used to treat contaminants to almost any depth in both the saturated and
unsaturated zone. However, their use becomes cost-prohibitive in very low
permeability soils because of the need to space the wells very close together to ensure
complete delivery or recovery. Subsurface drains can be used under conditions of
moderately low permeability, although delivery and recovery of chemicals will be
slow. They are generally limited to depths of 40 feet or less because of the cost
associated with excavation (shoring, dewatering, and hard rock excavation) of the
5/93 44
-------
BIOLOGICAL TREATMENT
trench. Surface gravity delivery systems (e.g., spray irrigation, flooding, and
ditches) that involve application of treatment solutions directly to the surface, as
illustrated by "surface flushing" in FIGURE 7, are most effective for treating shallow
contaminated zones located in the unsaturated zone. They can also be used to treat
contaminants in the saturated zone, provided the following conditions are met:
• The soil above the saturated zone (through which treatment solutions
percolate) is sufficiently permeable to allow percolation of treatment solutions
to the groundwater within a reasonable length of time
• Groundwater flow rates must be sufficient to ensure complete mixing of the
treatment solutions with the groundwater.
The feasibility and effectiveness of these methods are affected by topography and
climate.
FIGURE 8 shows the design of a groundwater injection/recovery system that is
currently being used for bioreclamation at an Air Force site (SAIC/JRB, 1985). The
system, which is designed to operate in moderately low permeability soils, consists
of nine pumping wells and four injection wells. Groundwater is pumped at an even
rate from the pumping wells to a central flow equalizer (surge tank). Flow is
metered from this tank into a length of pipe into which measured amounts of nutrients
and hydrogen peroxide are added. The treated water then flows to a distribution box
to be distributed at an even rate to each of the four injection wells. Overflow from
the equalization tank will flow into an onsite storage tank.
The injection/recovery system was designed using a two-dimensional, geohydrologic,
nonsteady flow model that simulated the flow of groundwater at the site in response
to an injection/recovery pumping system.
Important criteria used for the design of the injection/recovery system include the
following:
• The groundwater injection rate will be the same as the rate determined during
the field testing program
• All injected groundwater and associated elements are to be kept within the
site boundary to prevent the transport of contaminants to adjacent areas (this
implies that there may be some net groundwater pumpage at the site)
• The distance between the injection-pumping wells should be such that
approximately six injection-pumping cycles can be completed within a 6-
month period.
5/93 45
-------
BIOLOGICAL TREATMENT
Injtciion
Wei
View of
BioiccUmition of
Sol and Groundwaier
AefnJoo Zone
of CieunOwtltr Flow >—^v
FIGURE?
SIMPLIFIED VIEW OF GROUNDWATER BIORECLAMATION
5/93
46
-------
BIOLOGICAL TREATMENT
KEY t
(7) Puoplnj We 111
(7) Injection Veils
Untreated Crouadvater Lines
— — — Treated Groundvater Lines
FIGURES
PLAN VIEW OF EXTRCTION/INJECTION SYSTEM
USED AT AN AIR FORCE SITE
5/93
47
-------
BIOLOGICAL TREATMENT
FIGURE 9 illustrates an injection trench used in the treatment of the Biocraft site
(Jhaveri and Mazzacca, 1983). The trench was 10 feet deep by 4 feet wide by 100
feet long. The trench had a IS mil plastic liner installed on the bottom, back, ends,
and top such that reinjected water only flowed out of the front (downgradient) face
of the trench. About 40 feet of slotted steel pipe was installed horizontally in the
trench to carry reinjected water into the trench system. As water flowed into the
injection trench, the water was forced to exit only from the front face. Backflow is
minimized by this design feature. Barriers can also be used behind the trench and
extended to a point where backflow is further minimized. In extreme cases, total
control over backflow and plume containment can be obtained by installing a
circumferential wall barrier.
Optimum extraction and injection flow rates will many times be predetermined by
aquifer yield limits or hydraulic design for plume containment.
Aquifer flow rates should be sufficiently high so that the aquifer is flushed several
times over the period of operation. Thus, if the cleanup occurs over a 3-year period,
flow rates between injection and extraction wells should be such that a residence time
of 6 months or less occurs between the well pairs. This corresponds to six or more
flushes. Several recycles would result in (1) flushing of soils containing organics,
preventing the clogging caused by microorganism buildup because of increased flow
rate; (2) more even distribution of nutrients and organic concentration within the
plume; and (3) better and more controlled degradation. Flow rates and recycle
should not be high enough to cause excessive pumping costs, loss of hydraulic
containment efficiency because of turbulent conditions, corrosion, excessive
manganese deposition, flooding, or well blowout. The operating period will depend
on the biodegradation rate of the contaminants in the plume and the amount of
recycle. If the period of operation is excessively long (e.g. more than 5 years), the
operating costs of bioreclamation may outweigh the capital costs of another remedial
alternative.
Anaerobic Bioreclamation
Anaerobic treatment is generally not as promising for site remediation as aerobic treatment.
Anaerobic processes are slower, fewer compounds can be degraded, and the logistics of
rendering a site anaerobic have not been developed to date.
Anaerobic metabolism includes (1) anaerobic respiration, in which nitrate or sulfate may be
used by nitrate or sulfate reducers as a terminal electron acceptor and (2) interactive
fermentative/methanogenic processes, which are carried out by "methanogenic consortiums."
If it were possible to provide proper reducing conditions, degradation by methanogenic
processes would be promising. A considerable body of research indicates that methanogenic
consortiums are active in the subsurface and are capable of degrading certain organics
(Ehrlich et al., 1982; Parsons et al., 1982; and Suflita and Gibson, 1984). Most notably
methanogenic consortiums are able to degrade TCE, PCE, and other lower molecular weight
5/93 48
-------
u»
Piano View
ol Enilh Mound
I" Wtl
4" Dlamoloi Wntliod Stono
Front View
4" Dlirnlet Pintle
W«H Mind Slollid
^-Enlh Mound
Wiim^m
Plltlle Itnst
lOvnlipped 1-3 Tlm««)
7" Diimtler Win
Hand Slotted
4" Olnnotot
Wnl.id Slon*
Appioi. to*
i Sind Bin
I on Top _
I ot llnoi 6"
Sand Olf*
Oelow Llnir
c-.ir
too1
Gridt
Pintle Unm
Uppvd Z 3 TVrwtl
4" DUmdtf
Wlihtd Slont
Plulk Lhigi
Sind But
on Top
ol Llnci
Sind Bui
Bilow Llnti
(AppfO*. 1 Ft. Thick
No Liu Thin 8"!
w
1—I
o
s
o
I-H
n
>
r
H
>
H
FIGURE 9
CONFIGURATION OF REINJECTION TRENCHES
NOTE: Treated water exits only from one side of the trench.
Source: Jhaveri and Mazzacca, 1983
-------
BIOLOGICAL TREATMENT
halogenated organics that generally cannot be degraded by aerobic or other respiratory
processes. Reductive dehalogenation appears to be the primary mechanism involved in
degradation. Methanogenic consortiums are also able to degrade various aromatics,
halogenated aromatics, and some pesticides. Degradation of petroleum hydrocarbons, as well
as straight-chain and branched alkanes and alkenes, is not possible under methanogenic
conditions.
Methanogenic activity requires a very low redox potential, -250 mv or less. If O2, NO3", or
S042" are present, the redox potential will not be low enough. Currently, there are no
demonstrated methods for rendering a site anaerobic. When the contamination is shallow,
an aquitard is below the zone of contamination, and the flow of groundwater can be
contained, it might be possible to induce reducing conditions by flooding the site, (similar
to a rice paddy). Another possible method of rendering the site anaerobic would be to add
excessive amounts of easily biodegradable organics so that the oxygen would be depleted.
One other promising possibility might be to circulate groundwater to the surface through
anaerobic digesters or anaerobic lagoons. These methods may require long retention times
because of slow degradation rates under anaerobic conditions. There have been no reports
of pilot or field studies using anaerobic degradation under methanogenic conditions.
Nitrate respiration may be a feasible approach to decontaminating an aquifer. Denitrification
(the reduction of NO3 to NH3 or N2) has been demonstrated in contaminated aquifers.
Nitrate respiration was used successfully in the treatment of an aquifer contaminated with
aromatic and aliphatic hydrocarbons (TABLE 8) (Stief, 1984). Nitrate can be added in-line
along with other nutrients and intimate mixing with groundwater can occur. The cost is
moderate; all that is required is the nutrient feed system and an in-line mixer.
Nitrate, however, is a pollutant, limited to 10 ppm in drinking water. Consequently, it may
be more difficult to obtain permits for use of nitrate at a site than for oxygen or hydrogen
peroxide. Additionally, degradation rates under aerobic conditions are more rapid and a
broader range of compounds can be degraded. There is no reason why nitrate respiration
would be a better treatment approach given the amount of success that has been demonstrated
with aerobic treatment approaches to date.
Operation and Maintenance
Operation and maintenance of a bioreclamation process involve aspects of the
hydraulic system as well as the biological system. The hydraulic aspects relate to
pumps, extraction and injection wells, and injection trenches.
Monitoring a number of parameters is necessary to determine process performance.
Monitoring of groundwater can be performed at the injection and extraction wells,
as well as at monitoring wells. Monitoring wells should be placed onsite to monitor
process performance and offsite to monitor for pollutant migration and provide
background information on changes in subsurface conditions due to seasonal
fluctuation. TABLE 13 lists parameters that should be monitored and suggests
methods which can be used to monitor these parameters.
5/93 50
-------
BIOLOGICAL TREATMENT
In a biological system, pH should be maintained in a range between 6 and 8, and
concentrations of both nutrients and organics should be kept as uniform as possible
to protect against shock loading. Dissolved oxygen should be maintained above the
critical concentration for the promotion of aerobic activity, which ranges from 0.2
to 2.0 mg/1, with the most common being 0.5 mg/1 (Hammer, 1975).
Clogging of the aquifer, injection wells or trenches, or extraction wells by
microbiological sludge is a possibility. CDS Inc., installed two wells in each of their
injection trenches in case flushing was ever required to remove sludge. After IVi
years of operation, clogging had not occurred (Groundwater Decontamination
Systems, Inc., 1983). However, problems with biofouling and plugging of sparging
points was encountered during a spill cleanup conducted by Groundwater Technology
(Yaniga, Smith, and Raymond, 1984). This interfered with oxygen transfer and
necessitated frequent mechanical cleaning. When hydrogen peroxide was substituted
for air sparging in order to deliver increased quantities of oxygen to the aquifer, one
added benefit was that the hydrogen peroxide kept the wells free of heavy biogrowth.
The permeability of the aquifer could be reduced because of precipitation. Other
factors, such as dispersion of clays, could reduce aquifer permeability. When
calcium concentrations are high in the soil, phosphates can be rapidly attenuated
because they precipitate with calcium, and become unavailable for microbial
metabolism. Nutrient formulations should be devised with the help of experienced
geochemists to minimize problems with precipitation and dispersion of clays. One
company claims to have developed special soil preconditioners and nutrient
formulations which reduce these problems and maximize nutrient mobility and
solubility; however, no process performance data are available on these products.
Maintenance of the bacterial population at their optimal levels is also important,
especially for selective mutant organisms which tend to be more sensitive than
naturally occurring species. A continuous incubation facility operating at higher
temperatures and under more controlled conditions could be used to maintain the
microbial population. The high biomass-containing stream formed from such a
facility could then be reinjected via wells or trenches to reinnoculate the subsurface
continuously with microorganisms.
Aeration wells may be particularly susceptible to operational problems. If injected
gas fluidizes the material around it, soil substrata shifts can occur that may cause a
well blowout (free passage of air to the surface). The cone of influence in a blown-
out well will be greatly reduced, requiring the installation of a new well. The best
method to prevent blowouts is to keep gas velocities below those necessary to cause
fluidization, or to place wells deep enough so that overburden pressure prevents
excessive fluidization, or both (Sullivan, Chemineer Kinecs, Dayton, Ohio, personal
communication, 1983). Suntech stated that a number of aeration wells became
inoperative because of blowout during their groundwater cleanup in 1972 and had to
be replaced (Raymond, Jamison, and Hudson, 1976). This suggests that aeration
5/93 51
-------
BIOLOGICAL TREATMENT
well blowout could become a commonly encountered problem if attention is not paid
to the design criteria.
TABLE 13
RECOMMENDED PARAMETERS TO MONITOR
Parameter
Total organic carbon (TOC)
Priority pollutant analysis or
analysis of specific organics
Microbiology-cell enumerators
Temperature conductivity dissolved
oxygen (DO) pH
Alkalinity
Acidity, M&P
Chloride
NH3-N
NO3-N
PO4 all forms
SO4
Total dissolved solids (TDS)
Heavy metals (if present)
Hydrogen peroxide (H2O2)
Location
of Analysis
laboratory
laboratory
laboratory
field
field
field
field
laboratory
field
Media
groundwater
soil and
groundwater
soil and
groundwater
groundwater
groundwater
groundwater
groundwater
soil and
groundwater
groundwater
Analytical Method
TOC analyzer
CG/MS(1)
Direct counts. Plate
counts on groundwater
media or enriched media.
Plate counts with portable
water test kits (e.g., Soil
Test Inc., Evanston, IL).
In-situ water quality
monitoring instrument or
prepackaged chemicals;
field test kits.
Prepackaged chemicals/
field test kits; water
analyzer photometer (Soil
Test, Inc., Evanston, IL;
Lamotte Chemical,
Chestertown, MD).
Prepackaged chemicals/
test kits; GC/MS;
AAS.(2>
Prepackaged chemicals
for H2O2, test strips
available. Titanium
sulfate titration and
spectrophotometer
analysis for H2O2 for
greater accuracy.
(1) GC/MS = gas chromatography/mass spectrometry
(2) AAS = Atomic absorption spectrometry
5/93
52
-------
BIOLOGICAL TREATMENT
Technology Selection/Evaluation
Aerobic bioreclamation has been demonstrated to be effective in degrading organics
at more than 30 spill sites. Although it has not yet been demonstrated at hazardous
waste sites, it can be expected to be effective and reliable provided the organics are
amenable to aerobic degradation and the hydraulic conductivity of the aquifer is
sufficiently high. There are substantial research data to suggest that microorganisms
found at uncontrolled hazardous waste sites are wellacclimated to the wastes.
Effectiveness and reliability could be adversely affected by factors such as
precipitation, which could reduce the permeability of an aquifer.
Relative to conventional pump and treat methods, bioreclamation may be more
effective because it is capable of degrading organics sorbed to soils. Sorbed organics
are not removed using conventional pump and treat methods.
The nature of the delivery systems can affect the reliability of the bioreclamation
approach. Pumping systems are prone to mechanical and electrical failure.
However, repairs can be made relatively quickly. Subsurface drains are less prone
to failure since there are no electrical components. When mechanical failures do
occur, repairs can be both costly and time consuming.
Implementation of a remedial action involving bioreclamation will take longer than
excavation and removal of contaminated soils. Depending on the site, it could also
take longer than a conventional pump and treat approach. The advantage of in-situ
bioreclamation over a pump and treat approach is that in-situ biodegradation treats
contaminated subsurface soils, thereby removing the source of groundwater
contamination.
The increased time required for in-situ bioreclamation is primarily dependent on the
degradation rates, which are, in turn, dependent on oxygen availability. The form
in which oxygen is delivered to the subsurface and the aquifer permeability are the
critical factors. As discussed previously, far more oxygen can be delivered to the
subsurface in the form of hydrogen peroxide.
Other aspects of implementation are similar to implementation of conventional
pumping or subsurface drain systems with a few exceptions. Depending on the
hydraulic conductivity, drains or wells must generally be spaced closer together to
ensure nutrient and oxygen availability at all portions of the zone being treated. The
lower the flow rate of the nutrient/oxygen-enriched water and the more rapidly
nutrients and oxygen are attenuated, the closer the injection wells or drains must be
spaced. Well/drain spacing will also be dictated by the need, if any, to contain the
contaminant plume or treatment solution.
There are few additional safety hazards associated with in-situ bioreclamation aside
from those hazards normally associated with being on a hazardous waste site or a
drill site. Because wastes are treated in the ground, the danger of exposure to
5/93 53
-------
BIOLOGICAL TREATMENT
contaminants is minimal during a bioreclamation operation relative to excavation and
removal.
A nutrient/oxygen or nutrient/hydrogen peroxide solution does not represent an
environmental threat. Most of the nutrients will be used and attenuated by microbial
activity. If the form of the nutrient is carefully selected (e.g., ammonia-nitrogen
rather than nitrate-nitrogen), the remaining nutrients will not present an
environmental threat. The hydrogen peroxide will rapidly decompose in the
subsurface to oxygen and water.
The only treatment reagent that could pose a hazard, if used, is the concentrated
hydrogen peroxide solution prior to mixing with groundwater. Worker protection for
operations involving hydrogen peroxide outside of a closed container or pipe should
include the use of chemically resistant gloves, an apron, and a face shield. Safety
training in the use of hydrogen peroxide should be provided by qualified personnel.
Costs
Costs for biological in-situ treatment are determined by the nature of the site geology
and geohydrology, the extent of contamination, the kinds and concentrations of
contaminants, and the amount of groundwater and soil requiring treatment. There
is no easy formula for predicting costs. Costs provided for actual site cleanups
indicate that biological treatment can be far more economical as an alternative to, or
in conjunction with, excavation and removal or conventional pump and treat methods.
In-situ treatment costs include costs for well construction and pumping. Unit costs
for chemicals, nutrients, and hydrogen peroxide are provided in TABLE 14. Cost
data for actual and hypothetical site cleanups involving in-situ treatment are presented
below.
Total capital and research and development costs for cleanup of the Biocraft site
(TABLE 15) were $926,158, including $446,280 which was spent on process
development (R&D). Project costs also included the hydrogeological study, design
and operation of the groundwater injection and collection system, and the
biostimulation plant. Total operating costs, based on treating 13,680 gallons/day,
were approximately $226/day, or $0.0165/gal. The total cost including amortization
based on projected costs is $0.03S8/gal over a 3-year period. Prior to the biological
treatment program, contaminated water had been removed at a rate of 10,000
gal/month. The average disposal cost had been $0.3S/gal (Jhaveri and Mazzacca,
1984). The costs of biological treatment of an equal number of gallons is an order
of magnitude less than that for disposal. The Biocraft site employed surface
biological reactors and enhanced in-situ treatment by reinfiltrating oxygen and
nutrient-treated groundwater. Costs for in-situ treatment alone would have been less
because process plant design and equipment would not be included in an in-situ
approach.
5/93 54
-------
BIOLOGICAL TREATMENT
TABLE 14
CHEMICAL COSTS
Category
Acids
Bases
Chelating agents
Fertilizers
(Microbial nutrients)
Liming material
Oxidizing agents
Reducing agents
Precipitating agents
Surfactant
Anionic
Nonionic
Chemical
Hydrochloric acid, 20° Baume tanks
Nitric acid 36° to 42° Baume tanks
Sulfuric acid
Virgin, 100%
Smelter, 100%
Caustic soda, liquid 50%, low iron
Ammonium chloride
Citric acid
Ammonia, anhydrous, fertilizer
Ammonium chloride
Ammonium sulfate
Sodium monophosphate
Sodium diphosphate
Phosphoric acid
75 % , commerical grade
52-54% a. p. a., agricultural grade
Potassium muriate, 60 to 62%, minimum
Potassium chloride
Potassium-magnesium sulfate
Agricultural limestone (dolomite)
Lime
Hydrated lime
Hydrogen peroxide, 35 %
Potassium permanganate
Caustic soda, liquid 50%, low iron
Ferrous sulfate
Heptahydrate
Monohydrate
Witconate 605A
Witconate P-1020BV
(calcium sulfonates)
Adsee 799
Cost/Unit
$55-105/ton
$195/ton
$61-95. 9/ton
$48-65/ton
$255-285/ton
$18/100 Ibs
$0.81-$1.19/lb
$140-$215/ton
$18/100 Ibs
$73-79/ton
$55.75/100 Ibs
$54.50/100 Ibs
$27.5/100 Ibs
$43.10/unit-tona
$0.82-0.92/unit-ton
$105/ton
$59/ton
$3.50-34/tonb
$30.75-45/ton
$32.5-34.5/ton
$0.24/lb
$1.03-1.06/lb
$255-285/ton
130/ton
160/ton
0.65-0. 85/lbc
0.70-0. 88/lbc
0.75-0. 87/bc
* Unit-ton: 1 percent of 2,000 pounds of the basic constituent or other standard of the material. The percentage
figure of the basic constituent multiplied by the unit-ton price gives the price of 2,000 pounds of the material.
b Source: US EPA, J984a.
c Source: Witco Chemical Corp. , Houston, TX, personal communication, 1985: cost varies depending on quantity
purchased (drum, truckload, or bulk).
Source: Schnell, 1985, unless otherwise noted.
5/93
55
-------
VO
OJ
TABLE 15
SUMMARY OF PROJECT COSTS - BIOCRAFT LABORATORIES, WALDWICK, NJ
Task
A. Hydrogeological study-problem definition
B. In-house process development (R&D)
C. Groundwater collection/injection system total
1 . Design
2. Installation
D. Biostimulation plant design and construction total
1. Engineering design
2. Masonry construction
3. Equipment and miscellaneous installation
Actual
Expenditure
$73,948
$446,280
$184,243
($61,490)
($122,753)
$221,207
($58,400)
($73,975)
($88,832)
Unit Cost
—
Period of
Performance
1976-1978
1978-1981
1980-1981
1981
1981
1981
1981
CAPITAL AND R&D TOTAL $926,158
E. Operation & maintenance (O&M)
1. Utilities
i.) Electricity - 26.4 kw (24 hrs/day)
ii.) Steam - 72 pounds (33kg)/day @
90PSI
2. Maintenance (see text)
3. Nutrient Salts
$47.40/day
($46.82/day)
(58C/day)
$159.93/day
$19.20/day
7.39C/kwh
0.8C/pound
1983 rates
1981
1983
Total water treated - 13,680 gallons (51,779)/day O&M total: $226.53/day $0.0165/gallon
$0.004/1)
BIOLOGICAL TREATMENT
Source: US EPA, 1984b
-------
BIOLOGICAL TREATMENT
TABLE 16
ESTIMATED COSTS FOR HYPOTHETICAL BIORECLAMATIONS
USING HYDROGEN PEROXIDE AS AN OXYGEN SOURCE
Contamination
Formation
Flow Rate
Project Time
Estimated Costs
Site A
300 gallons
gasoline
Sand/gravel
50 gpm
6-9 months
$70-120M(1)
SiteB
2,000 gallons
diesel fuel
Fractured bedrock
10 gpm
18-24 months
$200-300M(1)
SiteC
10,000 gallons jet
fuel
Coarse gravel
100 gpm
18-24 months
$500-700M(1)
(1)M = 1000
Source: FMC, 1985
TABLE 16 presents the estimated site cleanup costs for hypothetical sites involving
the use of hydrogen peroxide as an oxygen source for the enhancement of in-situ
biodegradation (FMC, 1985). The cleanup of 300 gallons of gasoline from a sand
gravel aquifer over a period of 6 to 9 months is between $70,000 and $120,000 (Site
A). Cleanup of 3,000 gallons of diesel fuel from a fractured bedrock formation is
estimated to require 9 to 12 months and cost from $160,000 to $250,000.
5/93
57
-------
Section 10
-------
INCINERATION
STUDENT PERFORMANCE OBJECTIVES:
At the conclusion of this unit, participants will be able to:
• Identify at least four applicable wastes and briefly describe why they are
suitable for incineration
• Briefly describe the incineration process
• Briefly describe the following incinerator designs:
Rotary kiln
Fluidized bed
Infrared
• Briefly describe typical preparations needed for onsite use of
mobile/transportable incinerators.
5/93
-------
NOTES
INCINERATION
• Incinerator
• Heat materials to combustion
• Residual solids
• Combustion products released
INCINERATION
ADVANTAGES
• Established technology
• Destruction of organics
• Volume reduction
• Residues may be delisted
WASTE CHARACTERISTICS
• Btu > 8,000 Btu/lb
• Moisture - energy sink
• Inorganics > 5% alkali metals
corrosive
• Halogens > 8% dry weight
corrosive
5/93
Incineration
page 1
-------
NOTES
COMBUSTION FACTORS
• Time
• Temperature
• Turbulence
• Oxygen
PRINCIPLE ORGANIC
HAZARDOUS CONSTITUENTS
POHCs are substances that scientific
studies have shown to be toxic or have
carcinogenic, mutagenic.or teratogenic
effects on humans or other life forms
(Listed at 40 CFR 261 APR VIII)
PERFORMANCE STANDARDS
DESTRUCTION REMOVAL EFFICIENCY (ORE)
DRE=-
W1B-W.
out
w,
X100
in
where W = Mass feed rate of POHC in the waste
stream feed
W
out
Mass emission rate of the POHC in the
stack gas prior to release into the
atmosphere
RCRA 99.99% most wastes
Specific wastes 99.9999%
Incineration
page 2
5/93
-------
NOTES
PERFORMANCE STANDARDS
• HCI
>99% reduction or <1.8 kg/hr
• Particulates
<180 milligrams/dscm
INCINERATOR DESIGNS
• Rotary kiln
• Fluidized bed
• Infrared
Rotary Kiln Incinerator
Primiry Secondary -,
Conbuitlon CombuiUen JLlut
Ch.mb.r ctomt* «"
Tank
L*gtnd
1 Influent Wutt 4 Secondary Burner
2 Primary Burner t Scrubber Water
3 Aah 6 Flue Qa*
5/93
Incineration
page 3
-------
NOTES
Fixed Bed Fluldized Bed Circulating Bed
Ollga.
Low air flow Med. air flow High air flow
(0.5 ft per sec.) (5 ft. per sec.) (15 ft per sec.)
Circulating Bed Incinerator
Bolld Umuuni
F««d
INFRARED INCINERATION
• Continuous conveyor belt furnace
• Electric power
• 100 tons per day
Incineration
page 4
5/93
-------
NOTES
SYSTEM COMPONENTS
• Feed hoppers
• Primary chamber
• Secondary combustion chamber
• Scrubber system
PEAK OIL COMPANY
TAMPA, FLORIDA
• Oil rerefinery
Contaminated sludges and soil
Contaminated groundwater
CONTAMINANTS
• PCBs
• Lead
5/53
Incineration
page 5
-------
NOTES
Mobile Treatment
at CERCLA Sites
CHARACTERISTICS OF
MOBILE UNITS
• Typically smaller than permanent units
• Carried to site by truck or rail
• Include several components
MOBILE TREATMENT
ADVANTAGES
• Allows fast response to emerging situations
• Enhances availability of innovative
technologies
• Can easily tailor treatment to each site
• Handles most waste
• No danger from transportation of waste
Incineration
page 6
5/93
-------
NOTES
MOBILE TREATMENT
DISADVANTAGES
• Requires site preparation
• Operating expenses may be higher
• Possible negative reaction of local
community
ON-SITE INCINERATION
• Mobilization/demobilization
• Site preparation
• Utilities
• Support equipment
• Residuals/effluents handling
SITE PREPARATION
• Access roads
• Graded area for setup
• Concrete base
• Spill control
• Site security
5/93
Incineration
page 7
-------
NOTES
UTILITIES
• Process water
• Electric power
• Auxiliary fuel
SUPPORT EQUIPMENT
• Fuel storage
• Waste storage
• Process water
• Ash storage
• Solids preparation/handling
• Wastewater treatment
• Residual disposal
INCINERATION
Small applications: > $1000/ton
Large applications: < $300/ton
Incineration
page 8
5/93
-------
INCINERATION
General Description
Incineration occurs when a substance is heated to the point of combustion in the
presence of oxygen. Hazardous waste incinerators are specifically designed to
incinerate contaminated liquids, solids, and sludges in an environmentally safe
manner. The process is relatively simple:
1. Wastes are fed into a specialized piece of equipment called an incinerator.
2. Within the incinerator's combustion chamber the waste is heated in the
presence of oxygen to combustion temperatures.
3. Residual solids, called ash, are removed following combustion.
4. Combustion products are released to the atmosphere.
Incineration of wastes may be conducted offsite at a permitted facility or onsite
through the use of a mobile/transportable incinerator. Offsite incineration is normally
used for small volumes of hazardous wastes. The potential for waste spills along
transportation routes and the necessity of material handling at the remote facility are
compelling reasons for using onsite incineration when there are relatively high
volumes of waste to be treated.
A review of all the RODs for NPL sites through 1988 show that for all sites selected
to receive treatment, 38 percent selected incineration or another form of thermal
treatment. Therefore, thermal treatments are the most selected treatments for NPL
sites. Furthermore, incineration of RCRA and TSCA wastes is routinely done by
generators of these wastes. The reasons for selecting this technology include:
• It is an established technology
• It results in destruction of organic contaminants
• The volume of waste is reduced
• Residues may be delisted.
Applicable Wastes
Liquids, sludges, and solids may be incinerated. However, wastes with high organic
contents, low moisture contents, and low concentrations of metals are the best
candidates for this technology. Furthermore, wastes that contain high concentrations
5/93
-------
INCINERATION
of halogenated materials or organic phosphorus may cause problems with refractory
linings or pose emission control problems. TABLE 1 shows the waste characteristics
that impact incineration processes. Additionally, wastes that have a minimum BTU
value of 8,000 may sustain combustion without the addition of supplemental fuels.
TABLE 1
HIGH-TEMPERATURE THERMAL TREATMENT - GENERAL *
Characteristics
Impacting Process
Feasibility
Reason for Potential Impact
Data
Collection
Requirements
High moisture
content
Moisture content affects handling and feeding and has
major impact on process energy requirement.
Analysis for
percent moisture
Elevated levels of
halogenated organic
compounds
Halogens from Hcl, HBr, or HF when thermally treated;
acid gases may attack refractory material and/or impact
air emissions.
Quantitative
analysis for
organic Cl, Br,
and F
Presence of PCBs,
dioxins
PCBs and dioxins are required to be incinerated at higher
temperatures and long residence times. Thermal systems
may require special permits for incineration of these
wastes.
Analysis for
priority pollutant
Presence of metals
Metals (either pure or as oxides, hydroxides, or salts)
that volatilize below 2,000°F (e.g., As, Hg, Pb, Sn) may
vaporize during incineration. Those emissions are
difficult to remove using conventional air pollution
control equipment. Furthermore, elements cannot be
broken down to nonhazardous substances by any
treatment method. Therefore, thermal treatment is not
useful for soils with heavy metals as the primary
contaminant. Additionally, an element such as trivalent
chromium (Cr3*) can be oxidized to a more toxic valence
state, hexavalent chromium (Cr6*), in a combustion
system with oxidizing atmospheres.
Analysis for
heavy metals
Elevated levels of
organic phosphorous
compounds
During combustion processes, organic phosphorous
compounds may form phosphoric acid anhydride (P2O3),
which contributes to refractory attack and slagging
problems.
Analysis for
phosphorous
Applicable to fluidized bed, infrared, rotary kiln, wet air oxidation, and pyrolytic as well as
vitrification processes.
Source: USEPA, 1988
5/93
10
-------
INCINERATION
Process Description
Incineration is a combustion process, and all efficient combustion processes depend
on a balance of four components:
• Time
• Temperature
• Turbulence
• Oxygen.
Combustion is not instantaneous. It does require time for oxidation reactions to be
completed. However, the time it takes for any individual reaction to come to
completion is related to the temperature at which the reaction is being carried out.
Normally the higher the temperature, the faster the rate of reaction. Therefore, less
reaction time is required for oxidation reactions to be carried out at higher
temperatures. For incinerators that burn hazardous wastes, a retention time of
approximately 2 seconds at a temperature of about 2000°F is sufficient to oxidize
hazardous wastes to carbon dioxide, water vapor, and other components. This
assumes that the waste is in contact with an excess concentration of oxygen when the
temperature is reached. The contact of waste with oxygen inside the combustion
chamber is a function of the turbulence within the chamber. Turbulence caused by
air movement through the combustion chamber actually provides mixing of the waste
with air that is drawn through the incinerator's combustion chamber. If insufficient
mixing occurs, or if the quantity of oxygen is low, unreacted or partially reacted
wastes will be exhausted.
Ideally there should be no unreacted wastes exhausted from an incinerator. However,
even under ideal conditions it is difficult to achieve complete combustion for some
chemicals. Some substances are more stable than others under incineration
conditions. These include some highly halogenated substances such as carbon
tetrachloride and PCBs. The greatest concern is for substances that may be released
to the atmosphere that scientific studies have shown to have toxic, carcinogenic,
mutagenic, or teratogenic effects on humans or other life forms (listed at 40 CFR
261, App. VIII). Substances identified in that list which have the highest thermal
oxidation stability are designated as principle organic hazardous constituents (POHC)
by permit writers and are used as indicators of performance for hazardous waste
incinerators.
The performance of an incinerator is based on its destruction removal efficiency
(DRE) of a POHC within the wastestream. It is calculated according to:
5/93 11
-------
INCINERATION
r _ ur \
DRE = —"Lsai *. 100%
where:
Win = mass feed rate of a POHC to the incinerator
1 in
Wout = mass emission rate of the same POHC present in exhaust emissions.
The DRE for most hazardous wastes must be a minimum of 99.99 percent.
However, for a number of specific wastes, including PCBs and tetra-, penta-, and
hexachlorodibenzo-/?-dioxins and F020 through F023, F026, and F027 wastes (40
CFR 264.343), the DRE must be greater than, or equal to 99.9999 percent.
In addition to achieving the appropriate DRE for a given waste, the incinerator also
must not discharge paniculate matter in excess of 180 milligrams per dry standard
cubic meter (0.08 grains per dry standard cubic foot) based upon excess oxygen
determinations. Furthermore, acid gases may be formed when wastes that contain
chlorine atoms are incinerated. Therefore, the concentration of hydrogen chloride
discharged from a hazardous waste incinerator must be controlled if more than 1.8
kilograms per hour (4 pounds per hour) is generated. Both excess particulates and
acid gases may be controlled through the use of exhaust gas scrubbing systems.
There are several mobile/transportable incinerator designs that are used for hazardous
wastes. These include:
• Rotary kiln
• Fluidized bed
• Infrared
Regardless of the design, individual incinerators are designed to handle a limited
volume of waste per unit time. The rate at which a given volume of waste can be
incinerated is its design capacity. This is given in terms of BTUs, and may be given
as tons/day or tons/hour. The small transportable incinerators may be capable of
handling 1 ton/hour, whereas some of the larger units may be rated at 100 tons/day.
These rated capacities are based on the units' capabilities of heat transfer. The
assumption is made that all equipment is operating properly. In practice, material
feed systems, ash withdrawal systems, and air pollution control equipment often fail
to operate at maximum efficiency and, therefore, it is wise to find out the actual
operating capacity for a specific incinerator. Such information should be available
from the equipment vendor.
5/93 12
-------
INCINERATION
The rotary kiln design has been used more extensively for hazardous waste
incineration than other designs. This is because it is capable of incinerating both
solid and liquid waste. Additionally, the rotary kiln design is easily adapted to a
mobile/transportable system. FIGURE 1 is a schematic representation of a rotary
kiln incinerator. There are numerous variations of this basic design; however, a
typical rotary kiln includes:
• Solids feed system
• Rotary kiln
• Ash drop
• Air pollution controls
• Process stack.
5/93 13
-------
VO
OJ
p
§Q
a
33
s
r
z —
£ 2
2 °
S »
>. w
d-
o
05
n
n
A-
S. Sov/atx*- W«»e*
Suck
Z
O
-------
INCINERATION
Process operation involves the introduction of wastes and auxiliary fuel into the high
end of a cylindrical, refractory, lined kiln. TABLE 2 shows the waste characteristics
that impact rotary kiln processes. The kiln is heated to temperatures of 1,200 to
1,800°F, or up to 2,400°F if the system uses no afterburner. When the appropriate
temperature has been reached, waste materials are fed into the system. Solids often
are screened through a material classifier that will not permit material greater than
2 inches in diameter to enter the incinerator. The larger pieces of wastes may be
reduced in size by a material shredder or a pug mill before they are incinerated.
TABLE 2
ROTARY KILN INCINERATION *
Characteristics
Impacting Process
Feasibility
Oversized debris such as
large rocks, tree roots,
and steel drums
Volatile metals (Hg, Pb,
Cd, Zn, Ag, Sn)
Alkali metal salts,
particularly sodium and
potassium sulfate
(NaSO«, KS04)
Fine particle size of soil
feeds such as clay, silts
Ash fusion temperature
of waste
Heating value of waste
Reason for Potential Impact
Difficult to handle and feed; may cause
refractory loss through abrasion. Size
reduction equipment such as shredders must
be provided to reduce solid particle size.**
May result in high metals concentration in
flue gas, thus requiring further treatment.
Cause refractory attack and slagging at high
temperatures. Slagging can impede solids
removal from the kiln.
Results in high paniculate loading in flue
gases because of the turbulence in the rotary
kiln.
Operation of the kiln at or near the waste ash
fusion temperature can cause melting and
agglomeration of inorganic salts.
Auxiliary fuel is normally required to
incinerate wastes with a heating value of less
than 8,000 BTU.
Data
Collection
Requirements
Size, form, quantity of
oversized debris. Size
reduction engineering data.
Soil and stack gas analysis for
subject metals.
Percent Na, K.
Soil particle size distribution,
USGS *** soil classification.
Ash fusion temperature.
BTU content.
* See also TABLE 1, HIGH-TEMPERATURE THERMAL TREATMENT (GENERAL)
** See TABLES 3 and 4.
*** U.S. Geological Survey.
Source: USEPA, 1988
5/93
15
-------
INCINERATION
Immediately upon entering the kiln, the waste is heated. Substances that have low
thermal oxidation stability, such as gasoline or other petroleum by-products, will
combust early in the process and the energy that is released will minimize the need
for the addition of auxiliary fuel to maintain incineration temperatures. Substances
with high thermal oxidation stability will desorb from solids that they may have been
associated with and will volatilize. These thermally stabile compounds will combust
at the higher temperatures. Therefore, many rotary kiln incinerators are designed
with a secondary combustion chamber, or afterburner, which heats the volatilized
gases to the higher temperatures necessary for combustion. This secondary chamber
normally follows the ash drop and is just ahead of the induced draft fan. It is
important to keep a hazardous waste incinerator under negative pressure during
operation. This ensures that there will be no leakage of potentially harmful gases out
of the kiln or secondary combustion chamber. It also ensures that there will be
excess oxygen and adequate turbulence within the combustion chambers. The air
pollution control equipment may vary from system to system. However, many
incinerators use a wet scrubber design. These scrubbers often use an alkaline
scrubbing fluid (hydrated lime) to neutralize acid gases and remove airborne
particulates. Following this treatment, the gases are exhausted to the atmosphere
through a process stack.
Fluidized-bed incinerators consist of a refractory, lined vessel containing a bed of
inert, granular, sand-like material (sized crushed refractory). TABLE 3 shows the
waste characteristics that impact fluidized-bed processes. Solids, sludges, and liquids
can be injected directly into the bed or at its surface. If contaminated soil is being
processed, the soil mass acts as the bed material. Combustion air is forced up
through the bed to fluidize the material at a minimum critical velocity. The heating
value of the waste plus minimal auxiliary fuel maintains the desired temperature
within the vessel. Solids may be withdrawn on a continuous basis or they may be
circulated within the vessel. The circulating bed combustor is designed to permit
feeding limestone along with solids (FIGURE 2). The limestone will neutralize acid
gases that form. Therefore, a baghouse dust collector may be used instead of an acid
gas scrubber for air pollution control.
5/93 16
-------
INCINERATION
TABLE 3
FLUIDIZED BED INCINERATION*
Characteristics
Impacting Process
Feasibility
Reason for Potential Impact
Data
Collection
Requirements
Feed particle size
Large particle size affects feeding and removal
of solids from the bed. Solids greater than 1
inch (2.5 cm) must be reduced in size by
shredding, crushing, or grinding. (Note:
Waste-Tech fluid bed system can handle up to
3-in. feed.) Fine particles (clays, silts) result
in high paniculate loading in flue gases.
Size, form, quantity
of solid material; size
reduction engineering
data; soil particle size
distribution; USGS
soil classification.
Low-melting point
(less than 1,600°F)
constituents,
particularly alkali
metal salts and
halogens (e.g., Na,
Cl compounds)
Defluidization of the bed may occur at high
temperatures when particles begin to melt and
become sticky. Melting point reduction
(eutectics) may also occur. Alkali metal salts
greater than 5 % (dry weight) and halogen
greater than 8 % (dry weight) contribute to
such refractory attack, defluidization, and
slagging problems.
Ash fusion
temperature.
Ash content
Ash contents greater than 64% can foul the
bed. (Note: Waste-Tech's continuous bed
letdown, screening, and reinjection minimize
this type of problem.)
Ash content.
Waste density
As waste density increases significantly,
particle size must be decreased for intimate
mixing and heat transfer to occur.
Waste-bed density
comparison.
Presence of
chlorinated or
sulfonated wastes
These wastes require the addition of sorbents
such as lime or sodium carbonate into the bed
to absorb acidic gases or the addition of a flue
gas scrubbing system as part of the treatment
train.
Analysis for priority
pollutants.
* See also TABLE 1, HIGH-TEMPERATURE THERMAL TREATMENT (GENERAL)
Source: USEPA, 1988
5/93
17
-------
INCINERATION
Hot Vy»
FIGURE!
AN EXAMPLE OF A CIRCULATING BED COMBUSTOR
Source: GA Corp., undated
5/93
18
-------
INCINERATION
Infrared incinerators (FIGURE 3) use silicon carbide elements to generate thermal
radiation beyond the red end of the visible spectrum. TABLE 4 shows the waste
characteristics that impact infrared incineration processes. Solid materials that are
to be treated pass through the primary combustion chamber on a continuous belt and
are exposed to the radiation. The gaseous components pass into a secondary
combustion chamber where they are further treated with infrared energy or a
combination of infrared energy and conventional gas-fired burners. Air pollution
controls are similar to those used with rotary kiln incinerators.
Source: &A-ORD
FIGURE 3
BLOCK FLOW DIAGRAM OF INFRARED INCINERATION SYSTEM
5/93
19
-------
INCINERATION
TABLE 4
INFRARED THERMAL TREATMENT*
Characteristics
Impacting Process
Feasibility
Reason for Potential Impact
Data
Collection
Requirements
Nonhomogeneous feed size
Nonuniform feed size requires pre-
treatmem before feeding and con-
veyance through the system. The
largest solid particle size processable
is 1 to 2 inches. Debris such as
rocks, roots, and containers must be
crushed or shredded to allow for
feeding.**
Size, form, quantity
of solid material; size
reduction engineering
data.
Moisture content
Waste material is conveyed through
the system on a metal conveyor belt,
so soils and sludges must be firm
enough (usually >22% solids) to
allow for proper conveyance. Soils
and sludges with excess water content
(e.g., lagoon sediments) require
dewatering prior to feeding.**
Moisture analysis.
**
See also TABLE 1, HIGH-TEMPERATURE THERMAL TREATMENT
(GENERAL).
See TABLES 2 and 3
Source: USEPA, 1988
Onsite incineration of wastes requires a greater degree of preparation and planning
than offsite incineration. This is because the mobile unit must be erected onsite.
This can be similar to a major construction effort and will require:
• Mobilization/demobilization
• Site preparation
• Utilities
• Support equipment
• Residuals/effluents handling.
5/93
20
-------
INCINERATION
Mobilization/demobilization of equipment involves the set up and take down of the
incinerator and other support equipment. The amount of time involved for this
depends on the specific incinerator and existing site conditions. For small systems
a minimum set-up time will be 1 week under ideal conditions. For large-scale
systems, 6-8 weeks may be necessary. Furthermore, since onsite construction is
necessary, a crane is often needed to assist in assembly and take-down of the
incinerator. Demobilization may take an equivalent amount of time and will include
decontamination and disassembling the incinerator. The decontamination may be
operated with clean fuel for a specified period of time and/or the equipment may be
steam cleaned.
Before any equipment arrives onsite it will be necessary to ensure that the site is
ready to receive it. Site preparation includes:
• Access roads
• Graded, graveled area for setup
• Concrete base for incinerator and ancillary equipment
• Spill control/containment
• Site security (fencing).
In addition to these items, consideration must be given to the equipment that will be
used to feed the incinerator. If excavation is required, a sufficient volume of
excavated material should be stored so that the incinerator can remain in operation
when excavation equipment is temporarily inoperable.
All process operations require utilities so that they may function. These include:
• Process water
• Electric power
• Auxiliary fuel.
Supplying each of these is site specific. In urban areas, process water may be
supplied through municipal supplies, whereas in rural settings, a supply well may be
necessary. Check with the technology vendor for the power requirements of the
specific incinerator and the availability of such power from the local electrical utility.
At some remote sites it may be necessary to use diesel- or gasoline-powered
generators for power supply. Also, propane, natural gas, or fuel oil will be required
to operate the system. Provisions must be made to ensure that a consistent supply
will be available onsite before the system is mobilized.
5/93 21
-------
INCINERATION
Support equipment includes all the equipment necessary to ensure continued operation
of the systems. The specific equipment will vary depending on the site and the
system that will be used. Some of this equipment includes:
• Bulk fuel storage tanks
• Waste storage
• Process water tanks
• Ash storage
• Solids preparation/handling
• Wastewater treatment facilities
• Residual disposal.
Residuals/effluents include the solids, liquids, and gaseous materials produced as a
result of incinerator operation. Solids include the ash, slag, and fly ash that are not
combusted during the incineration process. Incineration of soil results in relatively
little volume reduction, because of its high volumes of incombustible materials. Wet
scrubbers produce a liquid wastestream that may contain alkaline wastes. These may
require additional treatment prior to discharge. Gaseous materials include the
combustion by-products and products of incomplete combustion (PIC). These are
directly discharged to the atmosphere through the process stack.
Monitoring
Waste characteristics can directly affect the performance of incinerators. Therefore,
it is essential that the data collection requirements outlined in TABLES 1 and 4 are
obtained prior to initiating processing.
Monitoring and inspection requirements for incineration of hazardous wastes are
listed in 40 CFR 265.347 and are presented in TABLE 5. In addition to these,
individual states may have specific monitoring and inspection requirements which are
designated as applicable or relevant and appropriate requirements (ARARs).
Provisions should be made to ensure that ash analysis is completed expeditiously.
This will minimize the amount of ash storage area necessary and will permit ultimate
disposal of the ash.
5/93 22
-------
INCINERATION
TABLE 5
MONITORING AND INSPECTION REQUIREMENTS
Monitoring Parameter
Combustion Temperature
Waste Feed Rate
Combustion Gas Velocity
Carbon Monoxide (between the
combustion zone and release
Ash Composition
Exhaust Emissions
Waste Feed Chemical Analysis
Inspection Parameter
Incinerator and Associated Equipment
Emergency Waste Feed Cutoff System
and Alarms
Frequency of Monitoring
Continuous
Continuous
Continuous
Continuous
Upon request of EPA Regional Administrator
Upon request of EPA Regional Administrator
Determined by EPA Regional Administrator
Frequency of Inspection
Daily
Weekly (or Monthly with Regional
Administrator consent)
Cost
Mobile/transportable incinerators are leased from firms that specialize in this
technology. Therefore, lease agreements are normally used to define costs associated
with this technology. Lease agreements vary from vendor to vendor; however, it is
usual to have the vendor supply operating personnel. An important item here is to
identify the limits of operation. Responsibilities for operation of incinerator feed
equipment and ash handling must be spelled out in any lease agreement. Failure to
do so may mean that the incinerator would be delivered and set up without a means
of conveying wastes to or from the unit.
Because many cost-related items are site specific, it is difficult to project overall costs
for incineration. However, in general, costs range from $200 to $1,000 per ton. An
estimate of the annual operating cost of a rotary kiln system is presented in TABLE
6. Compared with other technologies, incineration is expensive, but may be the least
cost option for specific wastes.
5/93
23
-------
INCINERATION
TABLE 6
ESTIMATE OF ANNUAL OPERATION AND
MAINTENANCE COSTS FOR A ROTARY KILN
Item
Personnel (1 supervisor, 2 operators, 4 yard-crew workers, 1 secretary.)
Electricity (473 hp) (7,200 h/yr.)
Water (3.2 x 108 gal./yr.)
Auxiliary fuel
Startup (10) (8 h) (10 x 105 BTU/h)
Operating (4.8 x 106 BTU/h) (7,200 h/yr.)
Chemicals (2.25 x 106 Ib. lime/yr.)
Effluent disposal:
Scrubber liquid (3.2 x 105 gal./yr.)
Ash (2.88 x 106 Ib/yr.)
Laboratory
Maintenance (10% of total equipment cost)
Refractory replacement (8-yr. life)
Direct operating cost
Value of recovered steam
Net operating cost
1985 Cost $/yr.*
$151,322
130,772
257,393
4,670
430,407
39,128
386,089
14,945
62,272
157,238
26,984
1,661,220
1,245,450
415,770
* Costs updated from 1983 to 1985 dollars using ENR Construction Index.
Adapted from Vogel and Martin, 1984.
5/93
24
-------
Section 11
-------
SOIL FLUSHING AND WASHING
STUDENT PERFORMANCE OBJECTIVES:
At the conclusion of this section, participants will be able to:
• Briefly describe the difference between soil washing and soil flushing, and list
at least two advantages and two disadvantages of each
• List at least four components of a typical soil flushing system
• Briefly describe the operation of a typical soil flushing system
• List at least four components of a typical soil washing system
• Briefly describe the operation of a typical soil washing system.
5/93
-------
NOTES
SOIL FLUSHING
• Desorbing and removing
contaminants from soil using
a liquid flushing solution
• In-situ process
5/93
Soil Flushing and Washing
paget 1
-------
NOTES
Soil Flushing and Washing
page 2
t
5/93
-------
NOTES
SOIL FLUSHING SOLUTIONS
• Water
• Acids and bases
• Complexing and chelating agents
• Surfactants
WATER FLUSHING
• Water-soluble organics
Ketones, aldehydes, aromatics,
and some halogenated
hydrocarbons such as TCE
(low to medium molecular
weight)
• Soil/water partition coefficient
WATER FLUSHING
• Water-soluble inorganics
Metal salts such as nickel,
zinc, and copper carbonates
• pH adjustment
5/93
Soil Flushing and Washing
page 3
-------
NOTES
ACID FLUSHING
• Metal salts and basic organics
Hydroxides, oxides, and
some carbonates
amines, ethers, and anilines
• Weak, low toxicity acids
Acetic acid, dilute sulfuric
acid
COMPLEXING/CHELATING
AGENT FLUSHING
• Water soluble metal-chelate
complexes
• Common agents
Ethylene diamine tetra acetic acid
(EDTA)
Diethylene triamine penta acetic acid
(DTPA)
SURFACTANT FLUSHING
• Non-soluble and hydrophobic
organics
• Emulsifies organics and desorbs
them from soil particles
• Laboratory/bench scale testing
recommended
Soil Flushing and Washing
page 4
5/93
-------
NOTES
FEASIBILITY STUDY
• Site geology
• Site hydrology
• Waste characteristics
• Soil characteristics
SOIL CHARACTERISTICS
• Soil type
Carbon content
Clay content
Other minerals
• Biological activity
• Soil characteristics
SOIL CHARACTERISTICS
• Density
• Porosity
• Permeability
• Water content
• Depth to contamination
5/93
Soil Flushing and Washing
page 5
-------
NOTES
Soil Flushing and Washing
page 6
SOIL WASHING
• Separating soil sizes and/or
desorbing and removing
contaminants from soil using
mechanical action and a liquid
flushing solution
• On-site process
>r
STONES
SPENT
FLUID
SOIL WASHER
SOIL FINES
SOIL FINES
CLEAN SAND
RAW FEED FINES WASHER
^
+
CLEAN
SOIL
5/93
-------
NOTES
SPENT
FLUID
RAW FEED SOIL FLOW
"-IT
CLEAN
SOIL
SPENT
FLUID
HAWFEEO LIQUID FLOW
CLEAN
SOIL
SOIL WASHING SYSTEM
Froth Flotation
Cells
5/93
So// Flushing and Washing
page 7
-------
SOIL FLUSHING AND WASHING
Soil Flushing
Organic and inorganic contaminants can be washed from contaminated soils by means of an
extraction process termed "soil flushing," "solvent flushing," "ground leaching," or "solution
mining." Water or an aqueous solution is injected into the area of contamination, and the
contaminated elutriate is pumped to the surface for removal, recirculation, or onsite treatment
and reinjection. During elutriation, sorbed contaminants are mobilized into solution by
reason of solubility, formation of an emulsion, or by chemical reaction with the flushing
solution.
Solutions with the greatest potential for use in soil flushing fall into the following classes:
• Water
• Acids and bases
• Complexing and chelating agents
• Surfactants
• Certain reducing agents.
Water can be used to flush water-soluble or water-mobile organics and inorganics.
Hydrophilic organics are readily solubilized in water. Organics amenable to water flushing
can be identified according to their soil/water partition coefficient or estimated using the
octanol/water partition coefficient. Octanol-water partition coefficients are available for a
large number of compounds in Substituent Constants for Correlation Analysis in Chemistry
and Biology (Hansch and Leo, 1979). Chemical Property Estimation Methods (Lyman, Reehl
and Rosenblatt, 1982) provides various methods for estimating the octanol-water partition
coefficient using readily available physical and chemical data. Organics considered soluble
in the environmental sense are ones with a partition coefficient (K) of approximately less than
1,000 (log K = 3). High solubility organics, such as lower molecular weight alcohols,
phenols, and carboxylic acids, and other organics with a coefficient less than 10 (log K£l)
may have already been flushed from the site by natural flushing processes. Medium
solubility organics (K = 10 to 1,000) that could be effectively removed from soils by water
flushing include low to medium molecular weight ketones, aldehydes, and aromatics, and
lower molecular weight halogenated hydrocarbons such as trichloroethylene (TCE) and
tetrachloroethylene (PCE). Inorganics that can be flushed from soil with water are soluble
salts such as the carbonates of nickel, zinc, and copper. Adjusting the pH with dilute
solutions of acids or bases (to be discussed) will enhance inorganic solubilization and
removal.
5/93
-------
SOIL FLUSHING AND WASHING
The remedial actions at the Goose Farm site in Plumstead, New Jersey, involved the
installation of a wellpoint collection and recharge system and the flushing of contaminants
from the soil with water (USEPA, 1984b). Water flushing has been used over a 5- to 6-year
period to reclaim a former herbicide factory site in Sweden (Truett, Holberger, and Sanning,
1982). Cleanup of a TCE spill in Germany involved water flushing of contaminated soils
and effected a 50-percent decrease in TCE over an 18-month period (Stief, 1984).
Dilute solutions of acids have been widely used in industrial processes to extract metal ions.
Solutions of sulfuric, hydrochloric, nitric, phosphoric, and carbonic acid are used in
industrial applications to dissolve basic metal salts (hydroxides, oxides, and carbonates).
However, because of the toxicity of many acids, it is desirable to use weak acids for in situ
treatment. Sodium dihydrogen phosphate (NaH2PO4) and acetic acid (CH3COOH) have low
toxicity and are reasonably stable. A stronger dilute acid such as sulfuric acid would be used
if the soil contained sufficient alkalinity to neutralize it. Acidic solutions may also serve to
flush some basic organics such as amines, ethers, and anilines.
Complexing and chelating agents may also find use in a solution mining removal system for
heavy metals. Some commonly employed substances are citric acid, ethylenediamine-
tetraacetic acid (EDTA), and diethylenetriaminepentaacetic acid (DTPA) (Rogoshewski and
Carstea, 1980). Chelating agents used for in situ treatment must result in a stable metal-
chelate complex that is resistant to decomposition and degradation.
Another possibility for mobilizing metals that are strongly adsorbed to manganese and iron
oxides in soils is to reduce the metal oxides which results in release of the heavy metal into
solution. Chelating agents or acids can then be used to keep the metals in solution.
Treatment agents that may be suitable for this purpose include hydroxylamine plus an acid
or sodium dithionite/citrate.
Surfactants can be used to improve the solvent property of the recharge water, emulsify
nonsoluble organics, and enhance the removal of hydrophobic organics sorbed onto soil
particles. Surfactants improve the effectiveness of contaminant removal by improving both
the detergency of aqueous solutions and the efficiency by which organics may be transported
by aqueous solutions (USEPA, 1985). Surfactant washing is among the most promising of
the in situ chemical treatment methods.
Numerous environmentally safe and relatively inexpensive surfactants are commercially
available. Use of surfactants to date has been restricted to laboratory research. Most of the
research has been performed by the petroleum industry for tertiary oil recovery (Barakat et
al., 1983; Cash et al., 1977; Doe, Wade, and Schecter, 1977; and Wilson and Brandner,
1977). Aqueous surfactants have also been proposed for gasoline cleanup. In a study
performed by the Texas Research Institute (1979) for the American Petroleum Institute, a
mixture of anionic and nonionic surfactants results in contaminant recovery of up to 40
percent. In a laboratory study conducted by Ellis and Payne (1983), crude oil recovery was
increased from less than 1 percent to 86 percent, and PCB recovery was increased from less
than 1 percent to 68 percent when soil columns were flushed with an aqueous surfactant
solution.
5/93 10
-------
SOIL FLUSHING AND WASHING
Characteristics of surfactants and their environmental and chemical properties are listed in
TABLE 1 (USEPA, 1985). This table can be used to aid in the preliminary selection of a
surfactant. However, laboratory testing of the surfactant should be performed to verify
surfactant properties.
An economically feasible soil flushing method may involve the recycling of elutriate through
the contaminated material, with make-up solvent being added to the system while a fraction
of the elutriate stream is routed to a portable wastewater treatment system. The appropriate
types of wastewater treatment operations will depend on wastestream characteristics.
The advantages of the soil flushing process are that, if the waste is amenable to this
technique, and distribution, collection, and treatment costs are relatively low, solution mining
can present an economical alternative to the excavation and treatment of the wastes.
Extraction/Soil Washing
Process Description
The extraction of contaminants from soil matrices by mixing the soils with water,
surfactants, chelating agents, or organic solvents has been applied at a number of
hazardous wastes sites. The process extracts the contaminants off the soil by the
principle of partitioning and then the leachate is treated for the removal of the
contaminants. Subsequently, the water may be reinjected to enhance the process.
The soils can be excavated into a loose pile or left undisturbed for in situ treatment
depending on the soil characteristics and the washing effectiveness.
This system can be used in conjunction with a mobile groundwater treatment system
in order to regenerate the leaching medium. The leaching of contaminated soils will
enhance the removal of source contaminants that threaten to enter the groundwater.
This will reduce the time required for site cleanup and groundwater remediation.
Combining a groundwater treatment system with a soil washing system will save
costs of both offsite trucking of soil materials and a stand-alone soil washing system.
A recent evaluation of the use of water flushing techniques for the extraction of
hydrophobic and slightly hydrophilic organics revealed that the addition of selective
water-soluble surfactants greatly enhanced the effective removal of these organics.
Additional field work has also demonstrated similar results for the removal of metals
from soils by adding chelating agents to the flushing medium. The washing fluid
may contain additives such as acids, alkalies, detergents, and selected organic
solvents that will enhance the transfer of contaminants from the soils.
5/93 11
-------
VO
to
TABLE 1
SURFACTANT CHARACTERISTICS
Surfactant Type
ANIONIC 1) Carboxy lie Acid Salts
2) Sulfuric Acid Ester Salts
3) Phosphoric & Polyphosphoric
Acid Esters
4) Perfluorinated Anionics
5) Sulfonic Acid Salts
CATIONIC 1) Long Chain Amines
2) Diamines & Polyamines
3) Quaternary Ammonium Salts
4) Polyoxycthylenated Long-Chain
Amines
NONIONIC 1) Polyoxyethylenated Alkylphenols
Alkylphenol Elhoxy iates
2) Polyoxyethylenated Straight
Chain Alcohols and Alcohol
Ethoxy iates
3) Polyoxyethylenated
Polyoxypropylene Glycols
4) Polyoxyethylenated Mercaptans
S) Long-Chain Carboxylic Acid
Esters
6) Alkylolamine "Condensates,"
Alkanolamides
7) Tertiary Acetylenic Glycols
AMPHOTERICS 1) pH Sensitive
2) pH Insensitive
Selected Properties & Uses
• Good Detergency
• Good Wetting Agents
• Strong Surface Tension
Reducers
• Good Oil in Water
Emulsifiers
• Emulsifying Agents
• Corrosion Inhibitor
• Emulsifying Agents
• Detergents
• Wetting Agents
• Dispersants
• Foam Control
• Solubilizing Agents
• Wetting Agents
Solubility
• Generally Water
Soluble
• Soluble in Polar
Organics
• Low or Varying Water
Solubility
• Water Soluble
• Generally Water
Soluble
• Water Insoluble
Formulations
• Varied (pH dependent)
Reactivity
• Electrolyte Tolerant
• Electrolyte Sensitive
• Resistant to
Biodegradation
• High Chemical Stability
• Resistant to Acid and
Alkaline Hydrolysis
• Acid Stable
• Surface Adsorption to
Siliceous Materials
• Good Chemical Stability
• Resistant to
Biodegradation
• Relatively Nontoxic
• Subject to Acid and
Alkaline Hydrolysis
• Nontoxic
• Electrolyte Tolerant
• Adsorption to
Negatively Charged
Surfaces
CO
o
CO
s
2
o
V)
a
2
o
Source: USEPA, 1985
-------
SOIL FLUSHING AND WASHING
Waste Type Handled
Contaminants amenable to this process include heavy metals (such as copper, lead,
and zinc), halogenated aliphatics (such as trichloroethylene, trichloroethanes, and
chloroform), aromatics (such as benzene, toluene, cresol, and phenol), and volatile
motor fuels (such as jet fuel spills and gasoline spills). Enhanced extraction with
surfactant additives has also been effective on hydrophobic organics (such as
polycyclic aromatic hydrocarbons, aliphatic and aromatic hydrocarbons,
polychlorinated biphenyls, and chlorinated phenol mixtures).
Soil characteristics such as soil type matrix (sand, gravel, or clay), low organic
content, and high hydraulic conductivity enhance this process. A sandy porous soil
with less than 1-percent organic content would be well suited for this treatment
process.
Restrictive Characteristics
A soil matrix with a high organic content and low water permeability will resist
desorption of the contaminants and may act as a binding agent, preventing natural
leaching of the contaminated soil. Low water permeability might indicate small
particle size and reduced interparticle void space. A reduced surface area for contact
between the water and the soil matrix will reduce the rate of contaminant transfer
from the soil into the water phase. Clay and silty soils may not be amenable for the
soil washing technique because interactions between soil surface and pollutants may
retard mobility of contaminants. Other factors that tend to decrease the mobility of
pollutants include chemical reactions with soil, cation exchange, and pH effects.
Another hinderance to this process has been the regeneration of water-surfactant
solutions losing the surfactants.
Mobile System Considerations
All systems employing this process are mobile and are set up at the contamination
site. Transportation costs for moving the soil would make this system uneconomical.
The most common method to employ this technique is in conjunction with a
contaminated groundwater treatment system where the treated groundwater is
reinjected upgradient (sprayed above soils if in the unsaturated zone) and leaches
through the in situ contaminated soil matrix. The leachate is then recollected,
treated, and reinjected back into the system, thus providing for a closed-loop system.
Variations to this process include aboveground contacting systems such as
countercurrent extraction equipment, a pug mill, a truck-loaded cement mixer, etc.
A soil scrubbing system treating excavated contaminated soils can provide a more
effective removal process through better soil-water contact and enable less water
volume to be used for an equivalent waste removal process. The washing fluid may
contain additives such as acids, alkalies, detergents, and selected organic solvents that
may enhance soil decontamination.
5/93 13
-------
SOIL FLUSHING AND WASHING
The major site-specific conditions that dictate the successful implementation of this
process are the soil properties related to organic content porosity, permeability, pH,
and temperature. Each site is truly unique for this application and actual laboratory
and field studies have to be performed before recommending this process. The soil
scrubbing technique in connection with a conventional groundwater treatment system
can tolerate much higher soil-water partition coefficients and more washing fluid
volume throughout than soil washing systems without groundwater treatment systems
because of the major cost of regenerating the washing medium.
Environmental Impacts
The leaching medium must be reused for economic reasons; therefore, regeneration
of the liquid must also be accomplished along with soil washing. The leachate
collected from the contacting process can be recycled by selecting a treatment process
for the particular contaminants (i.e., air stripping of water for VOC removal). The
separation of the extracted contaminants from the washing fluid can be accomplished
by conventional treatment systems suited to the particular contaminants. Problems
have arisen with the use of water/surfactant systems because a leachate treatment
system has not yet been developed to selectively remove contaminants and pass the
surfactants through intact.
Costs
Several cost systems have been employed at hazardous waste sites. However, none
have been developed to commercial status for estimating costs. The soil washing
system used at Lee's Farm, Wisconsin, had an estimated cost of about
$150-$200/yd3 excluding development costs. The major cost of the project is usually
associated with the leachate treatment system.
Commercial Applications
Currently, several hazardous waste sites throughout the country employ this
extraction/soil washing technique for the cleanup of contaminated soils. Some have
reached more developed stages than others, but all have had to test this system on
the site-specific conditions of concern.
Sites where this technology has been used include:
• Volk Air National Guard Base, Juneau County, Wisconsin, performed by the
Air Force Engineering and Service Center, Tyndall AFB, FL 32403-6001.
"In Sim Treatment of JP-4 Contaminated Soil."
Soils contaminated with volatile organics were leached with water/2-percent
surfactant and the leachate was regenerated by air stripping.
5/93 14
-------
SOIL FLUSHING AND WASHING
• Lee's Farm Wisconsin, Battery Manufacturing. Wastes include lead, zinc,
copper, etc. Contact Charlie Castle, on-scene coordinator in EPA Region
V, 312/535-2318.
Lead-contaminated soils were leached with water/5-percent EDTA and the leachate
was regenerated by electrolysis.
• Celtor Chemical Works, Hoopa Indian Reservation, Ore Enrichment Plant.
Tailings include cadmium, copper and zinc. Contact Nick Morgan, project
manager for EPA Region IX, 916/243-5831.
5/93 15
-------
SOIL FLUSHING AND WASHING
APPENDIX I
INNOVATIVE TECHNOLOGY
SOIL WASHING
Technology Description
Soil washing is potentially
effective in treating various
organic and inorganic waste
groups. It was designed for
the separation/segregation
and volumetric reduction of
hazardous materials in soils,
sludges, and sediments. The
process involves high-energy
contacting and mixing of
excavated contaminated soils
with an aqueous-based
washing solution in a series
of mobile washing units. A
typical soil washing treatment
flow diagram is shown in
FIGURE 1.
Before treatment, the con-
taminated soil is passed
through a coarse-mesh sieve
to remove material greater
than 2 inches (e.g., rocks,
debris). The remaining
material then enters a soil
scrubbing unit, where it is
sprayed with a washing fluid
and subsequently rinsed.
Contaminants are primarily
concentrated in the fine-
grained soil fraction (i.e., silt
and clay) and are less tena-
ciously sorbed on the
coarser-grained particles
(i.e., sand). Accordingly,
the sand fraction of the soil
usually requires only the
initial rinsing treatment to
meet designated performance
criteria prior to redeposition.
The remaining silt/clay soil
fraction enters a four-stage
countercurrent contactor to
further separate the co'ntam-
inants from the solids. The
treated solid fractions (less
than 74 microns) are then
rinsed, dewatered, and
redeposited. The contam-
inated washing fluid, con-
taining highly contaminated
fine fractions (greater than
74 microns) is recycled
through a conventional
wastewater treatment system
and is reintroduced into the
treatment process. The fines
are separated, removed, and
dewatered and are handled/
disposed of as a manifested
hazardous waste material.
Advantages of soil washing
include a closed treatment
system that permits control
of ambient environmental
conditions, potential signi-
ficant volume reduction of
the contaminant mass (depen-
ding on soil characteristics),
wide application to varied
waste groups, mobility of
technology (hazardous wastes
remain onsite), and relati-
vely low cost compared to
other multicontaminant treat-
ment technologies. Disad-
vantages include (1) little
reduction of the contaminant
toxicity, (2) potentially
hazardous chemicals (e.g.,
chelating washing solutions)
may be brought onsite to be
used in the process, and (3)
The chemicals may be
difficult to remove from the
treated soil fraction.
Applications and limitations
of soil washing are discussed
in the following sections.
Site Characteristics
Affecting Treatment
Feasibility
Soil washing has the potential
to treat a wide variety of
contaminants such as heavy
metals, halogenated solvents,
aromatics, gasoline and fuel
oils, PCBs, and chlorinated
phenols. The projected ef-
fectiveness of this treatment
on general contaminant
groups is provided in
TABLE 1-1; treatability tests
are required to determine the
feasibility of soil washing for
specific target contaminants
at a particular site.
Factors limiting the effective-
ness of soil washing include
complex waste mixtures,
high humic content in the
soil, inhibiting solvent-soil
reactions, and a high fine-
grained clay particle fraction.
5/93
16
-------
SOIL FLUSHING AND WASHING
f~f^~ff \J~ ~tf~ltfm • /" ¥ J1 1 f
^J^**- I/" *f •*.*'
# ScTMnog
' (Dcbnt
FIGURE 1-1
SCHEMATIC DIAGRAM OF A MOBILE SOIL WASHING TREATMENT FACILITY
5/93
17
-------
SOIL FLUSHING AND WASHING
TABLE 1-1
EFFECTIVENESS OF SOIL WASHING TREATMENT ON GENERAL
CONTAMINANT GROUPS FOR SOIL AND DEBRIS
Treatability Groups
Halogenated volatiles
Halogenated semivolatiles
Nonhalogenated volatiles
Nonhalogenated semivolatiles
PCBs
Pesticides
Dioxins/furans
Organic cyanides
Organic corrosives
Volatile metals
Nonvolatile metals
Asbestos
Radioactive materials
Inorganic corrosives
Inorganic cyanides
Oxidizers
Reducers
Effectiveness
Q
Q
Q
Q
Q
Q
9
Q
Q
Q
Q
Q
9
O
Q
Q
Q
5/93
18
-------
SOIL FLUSHING AND WASHING
APPENDIX II
FIGURE II-l
VOLUME REDUCTION UNIT - SOIL WASHING PROCESS
5/93
19
-------
VO
u>
K)
O
o
H
O
>
r
§
M
o
V}
w
Wato I It AIM
Scr«*««d So* Fmciloot (» t/Zlndi)
(• 12.000 irknxn)
W«h«J tot (• 12.000 to . 2.000 micron*)
Wa^wd W3« (-2.000 to » 250 rricrom)
Stud9e«Conlan*ut*d PlnM (-2SO lo 35 n
Wa*l««ral«< lor AnalfiJi (Flrwt Ftocoilalhxv)
Wavtawatw (or Ajiftlytl* (Wxlaf CLiillcatlon)
F»«r Cifc* tor O
2:
o
C/3
a
^H
2
O
-------
Section 12
-------
IMMOBILIZATION
STUDENT PERFORMANCE OBJECTIVES:
At the conclusion of this unit, participants will be able to:
• List at least two advantages of using immobilization
• Briefly describe the functional differences between absorbants and stabilizers
• Briefly describe cement-based, silicate-based, and thermoplastic
immobilization processes
• List four types of immobilization systems
• Briefly describe vitrification.
5/93
-------
NOTES
IMMOBILIZATION
• A process designed to render
contaminants less soluble, mobile,
and/or toxic
• The process prevents leaching from a
solid matrix
IMMOBILIZATION
ADVANTAGES
• Improves waste handling
• Decrease in surface area
• Limited solubility or toxicity
• Readily available materials
• Large number of suppliers
IMMOBILIZATION
DISADVANTAGES
• Not a destruction technology
• Increase in waste volume
• Unproven for long-term leachability
5/93
Immobilization
page 1
-------
NOTES
ABSORBANTS
Physically hold liquid waste within
pores by capillary action or tension
Vermiculite
Fuller's earth
Bentonite
Fly ash
Saw dust
STABILIZERS
Chemically react with waste to
remove free liquids and produce a
monolith block
Portland cement
Pozzolanic material
(lime with silicates)
Fly ash
Kiln dust
IMMOBILIZATION PROCESSES
• Cement-based process
• Silicate-based process
• Thermoplastic process
Immobilization
page 2
5/93
-------
NOTES
CEMENT-BASED PROCESS
• Mixing waste with Portland cement
• Waste incorporated into matrix
• Waste not chemically bound and Is subject to
leaching, needs secondary containment for
disposal
• Not effective in immobilizing organics
• Incompatible waste:
Sodium salts of arsenate, borate, phosphate,
iodate, and sulfide
CEMENT-BASED PROCESS
• Preparation: limestone, clays, and silicates are fired In
a rotary kiln at 3000 degrees F
• Type I - Normal strength
• Type II • Moderate sulfate resistance
• Type III - High early strength
• Type IV • Low heat of hydration
• Type V • High sulfate resistance
• Type K • Low matrix shrinkage
SILICATE-BASED PROCESS
Stabilizes waste oil, solvents, and metals
Interference
Secondary containment required
Unbound water may leach out
5/93
Immobilization
page 3
-------
NOTES
SILICATE-BASED PROCESS
• Reaction between silicate material and polyvalent
metal ions
Silicate material such as fly ash, blast furnace
slag, or other types of pozzolanic material is
added to the waste
Polyvalent metal ions from the waste or added
setting agents initiate the solidifying process
The best setting agents are lime, gypsum,
Portland cement, and calcium carbonate
(Al, Fe, Mg)
THERMOPLASTIC PROCESS
• Asphalt, paraffin, and polyethylene
• Waste is dried, heated, then added to the
matrix
• Heavy metals and electroplating waste
• Incompatible waste:
Nitrates and perchlorates
Xylene and toluene
Solvents and greases
Immobilization
page 4
5/93
-------
IMMOBILIZATION
SOLIDIFICATION/STABILIZATION
Solidification and stabilization are terms used to describe treatment systems that accomplish one or
more of the following objectives (USEPA, 1982b):
« Improve waste handling or other physical characteristics of the waste
• Decrease the surface area across which transfer or loss of contained pollutants can occur
• Limit the solubility or toxiciry of hazardous waste constituents.
Solidification is used to describe processes where these results are obtained primarily, but not
exclusively, by production of a monolithic block of waste with high structural integrity. The
contaminants do not necessarily interact chemically with the solidification reagents, but are
mechanically locked within the solidified matrix. Contaminant loss is minimized by reducing the
surface area. Stabilization methods usually involve the addition of materials that limit the solubility
or mobility of waste constituents even though the physical handling characteristics of the waste may
not be improved (USEPA, 1982b; Cullinane and Jones, 1985). Methods involving combinations of
solidification and stabilization techniques are often used.
Solidification/stabilization methods can be categorized as follows:
• Cement solidification
• Silicate-based processes
• Sorbent materials
• Thermoplastic techniques
• Surface encapsulation
• Organic polymer processes
• Vitrification.
Detailed discussions of solidification/stabilization methods can be found in Guide to the Disposal of
Chemically Stabilized and Solidified Waste and Technical Handbook for Solidification of Hazardous
Waste (Cullinane and Jones, 1985).
5/93
-------
IMMOBILIZATION
These documents should be consulted for detailed information on these processes. Many
manufacturers are marketing processes that use various combinations of alkaline earth materials (e.g.,
lime, cement kiln dust, silicaceous materials, and cement) combined with organic polymers and
proprietary chemicals.
Cement-Based Solidification
General Description
This method involves mixing the wastes directly with Portland cement, a very
common construction material. The waste is incorporated into the rigid matrix of the
hardened concrete. Most solidification is done with Type I Portland cement, but
Types II and V can be used for sulfate or sulfite wastes. This method physically or
chemically solidifies the wastes, depending on waste characteristics (USEPA, 1982b).
The end product may be a standing monolithic solid or may have a crumbly, soil-like
consistency, depending on the amount of cement added.
Applications/Limitations
Most hazardous wastes slurried in water can be mixed directly with cement and the
suspended solids will be incorporated into the rigid matrix. Although cement can
physically incorporate a broad range of waste types, most wastes will not be
chemically bound and are subject to leaching.
Cement solidification is most suitable for immobilizing metals because at the pH of
the cement mixture, most multivalent cations are converted into insoluble hydroxides
or carbonates. However, metal hydroxides and carbonates are insoluble only over
a narrow pH range and are subject to solubilization and leaching in the presence of
even mildly acidic leaching solutions (e.g., rain). Portland cement alone is also not
effective in immobilizing organics.
The end product of cement solidification will not be acceptable for disposal without
secondary containment regardless of whether the wastes are organic or inorganic in
nature. Another major disadvantage is that cement-based solidification results in
wastes that are twice the weight and volume of the original material, thereby
increasing transportation and disposal costs (USEPA, 1982b). Because of these
limitations, Portland cement is generally used only as setting agent in other
solidification processes, particularly silicate-based processes.
Another problem with cement solidification is that certain wastes can cause problems
with the set, cure, and permanence of the cement waste solid unless the wastes are
pretreated. Some of these incompatible wastes are (USEPA, 1982b):
• Sodium salts of arsenate, borate, phosphate, iodate, and sulfide
• Salts of magnesium, tin, zinc, copper, and lead
5/93
-------
IMMOBILIZATION
• Sodium salts of arsenate, borate, phosphate, iodate, and sulfide
• Salts of magnesium, tin, zinc, copper, and lead
• Organic matter
• Some silts and clays
• Coal or lignite.
Major advantages to the use of cement include its low cost and the use of readily
available mixing equipment.
Costs
Cement costs range from $60 to $90 per ton at the mill. However, capital
expenditure and transportation will vary widely depending on the site and the waste.
Cost information for specific wastes should be obtained from vendors. Vendors
include Atcor Washington, Inc., Park Mall, Peeksville, New York, and Chemfix,
Inc., Kenner, Louisiana.
Silicate-Based Processes
General Description
Silicate-based processes refer to a very broad range of immobilization methods that
use a siliceous material plus lime, cement, gypsum, and other suitable setting agents.
Extensive research is currently underway on the use of siliceous compounds in
solidification. Many of the available processes use proprietary additives and claim
to stabilize a broad range of compounds from divalent metals to organic solvents.
The basic reaction is between silicate material and polyvalent metal ions. The silicate
material that is added in the waste may be fly-ash, blast furnace slag, or other readily
available pozzolanic materials. Soluble silicates such as sodium silicate or potassium
silicate are also used. The polyvalent metal ions, which act as initiators of silicate
precipitation and/or gelation, come either from the waste solution, an added setting
agent, or both. The setting agent should have low solubility and a large reserve
capacity of metallic ions so that it controls the reaction rate. Portland cement and
lime are most commonly used because of their ready availability. However, gypsum,
calcium carbonate, and other compounds containing aluminum, iron, and magnesium
are also suitable setting agents. The solid that is formed in these processes varies
from a moist, clay-like material to a hard, dry solid similar in appearance to concrete
(Granlund and Hayes, undated).
5/93
-------
IMMOBILIZATION
Some of the additives used in silicate-based processes include (Cullinane and Jones,
1985):
• Selected clays to absorb liquid and bind specific anions or cations.
• Emulsifiers and surfactants that allow the incorporation of immiscible organic
liquids.
• Proprietary absorbents that selectively bind specific wastes. These materials
may include carbon, zeolite materials, and cellulosic sorbents.
There are a number of silicate-based processes that are currently available or are
under research. Manufacturers' claims differ significantly in terms of the capabilities
of these processes for stabilizing different waste constituents.
The Chemfix process uses soluble silicates with cement as the setting agent.
Research data show that the process can stabilize sludges containing high
concentrations of heavy metals even under very acidic conditions (Spencer,
Reifsnyder, and Falcone, 1982).
The Envirosafe I process uses fly ash as the source of silicates and lime as the
alkaline earth material. This method has been shown to stabilize oil-bearing sludge
(49 percent oil and grease) and neutralize inorganic metal sludge. Success was
demonstrated by suing compressive strength tests following ASTM methods (TABLE
1) and leaching tests (Smith and Zenobia, 1982) (TABLE 2).
The DCM cement shale silicate process is a proprietary process formulated by
Delaware Custom Material, Inc., State College, Pennsylvania. It involves use of
cement, an emulsifier for oily wastes, and sodium silicate. Testing by Brookhaven
National Laboratories showed that the process could stabilize oily wastes with up to
a 30-percent volumetric loading (Clark, Colombo, and Neilson, 1982).
Manufacturers claim that the process can be used to solidify wastes containing acids,
organic solvents, and oils (Hayes and Granlund, undated).
PQ Corporation of Lafayette Hill, Pennsylvania, has done extensive research on the
use of silicates. Their research describes successful stabilization of a mixed heavy
metal/organic sludge; a waste containing high levels of organics and petroleum by-
products; and a waste containing organic solvents using modifications of the process
that uses sodium silicates (Spencer, Reifsnyder, and Falcone, 1982).
5/93
-------
IMMOBILIZATION
TABLE 1
PHYSICAL AND CHEMICAL TESTS
USED IN THE CHEMFIX SITE DEMONSTRATION
Name of test
Unconfmed compressive
strength (UCS)
Hydraulic conductivity
Wet/dry resistance
Freeze/thaw resistance
Oxidation/reduction
Electrical conductivity
Reference
ASFHM D1633
EPA draft protocol
ASTM D4843
ASTM D4842
EPA Method 9045
(modified)
ASA 10.-3.3
Description
Used to assess structural
integrity of monolith
Used to assess resistance of
material to water flow
Indication of durability in
wet/dry environment
Indication of durability in
wet/dry environment
Determine oxidation/
reduction state of waste
matrix
Determine amount of ionic
materials present in solution
TABLE 2
LEACHING TESTS USED IN THE CHEMFIX SITE DEMONSTRATION
Name of Test
TCLP
MEP
ANS 16.1
Reference
40 CFR Part 268
EPA Method 1320
(SW 846)
American Nuclear
Society 16.1
Description
Ground material subject to 18-hour
extraction process with acetic acid
leachate to simulate codisposal
environment with municipal waste
Ground material subject to 24-hour
extraction with acetic acid leachate
followed by nine sequential extractions
with acidic rain simulated leachate
Monolithic material placed in distilled
water that is replaced over discrete
time intervals (diffusion model)
5/93
-------
IMMOBILIZATION
Applications/Limitations
There is considerable research data to suggest that silicates, used together with lime,
cement, or other setting agents, can stabilize a wide range of materials including
metals, waste oil, and solvents. However, the feasibility of using silicates for any
application must be determined on a site-specific basis, particularly in view of the
large number of additives and different sources of silicates that may be used. Soluble
silicates such as sodium and potassium silicate are generally more effective than fly
ash, blast furnace slag, etc.
There are some data to suggest that lime-fly ash materials are less durable and stable
to leaching that cement fly ash materials (Cullinane and Jones, 1985).
Common problems with lime-fly ash and cement-fly ash materials relate to
interference in cementitious reactions that prevent bonding of materials.
Materials such as sodium borate, calcium sulfate, potassium dichromate, and
carbohydrates can interfere with the formation of bonds between calcium silicate and
aluminum hydrates. Oil and grease can also interfere with bonding by coating waste
particles (Cullinane and Jones, 1985). However, several types of oily sludges have
been stabilized with silicate-based processes.
One of the major limitations with silicate-based processes is that a large amount of
water, which is not chemically bound, will remain in the solid after solidification.
In open air, the liquid will leach until it comes to some equilibrium moisture content
with the surrounding soil. Because of this water loss, the solidified product is likely
to require secondary containment.
Silicate-based processes can employ a wide range of materials, from those which are
cheap and readily available, to highly specialized and costly additives.
The services of a qualified firm are generally needed to determine the most
appropriate formulation for a specific waste type.
Implementation Considerations
Commercial cement mixing and handling equipment can generally be used for
silicate-based processes. Equipment requirements include chemical storage hoppers,
weight- or volume-based chemical feed equipment, mixing equipment, and waste
handling equipment. Ribbon blenders and single and double shaft mixers can be used
for mixing. A number of mobile, trailer-mounted systems are available.
Silicate-based solidification can also be accomplished on a batch basis in drums.
Equipment requirements include onsite chemical storage system, chemical batching
system, mixing system, and drum handling system. One company has developed a
solidification kit for processing wastes in a drum. The kit consists of a drum
5/93 10
-------
IMMOBILIZATION
containing a disposable mixer blade with the shaft held by bearings welded to the
inside of the lid and the bottom of the drum. The upper end of the shaft is accessible
through a bung in the lid for turning with an external motor. The cement can be
added to the drum before it is capped. The liquid waste and silicate are added
through bungs in the lid. An air-driven motor is clamped to the drum lid to turn the
mixer (Granlund and Hayes, undated).
Solidification can also be accomplished in situ using a lagoon or mixing pit. This
would involve the use of common construction machinery such as a backhoe or pull
shovel to mix the waste and reagents. However, the ability of in situ solidification
to prevent leaching of contaminants would need to be demonstrated on a case-by-case
basis.
Costs
TABLE 3 provides estimated costs for silicate solidification using three different
mixing methods: in-drum mixing, in situ mixing, and a mobile cement mixing
system. In all cases it was assumed that 500,000 gallons (2,850 tons) of wastes were
solidified with 30-percent Portland cement and 2-percent sodium silicate. Onsite
disposal was assumed. These costs are intended mainly to show the relative cost of
various mixing methods and the proportion of total cost for reagents, equipment, and
labor. It should be emphasized that actual costs are highly waste and site specific and
that specific site and/or waste characteristics could change these cost estimates by
several fold.
In-drum mixing is by far the most expensive alternative and requires the greatest
amount of labor and production time. Because of the high cost, in-drum mixing is
limited to sites with highly toxic or incompatible wastes in drums (Cullinane and
Jones, 1985).
The cost of in situ mixing and mobile treatment are much more comparable. All are
quite sensitive to reagent cost because this cost typically makes up from 40 to 65
percent of the total cost. The in situ technique is the fastest and most economical of
the bulk-methods because the wastes typically only have to be handled once, or not
at all if they are to be left in place. Labor and equipment each made up less than 5
percent of the total treatment cost. However, in situ mixing is the least reliable
because of difficulties in accurate reagent measurement and difficulties in getting
uniform and/or complete mixing of wastes and treatment reagents. Mobile mixing
plants, although giving excellent mixing results and reasonably good production rates,
require that both the treated and untreated product be handled, thereby increasing the
costs above those for in situ treatment.
5/93 11
-------
IMMOBILIZATION
TABLE 3
SUMMARY COMPARISON OF RELATIVE 1985 COSTS OF
STABILIZATION/SOLIDIFICATION ALTERNATIVES1
Parameters
Metering and mixing
efficiency
Processing days required
In-drum3
Good
374
Plant Mixing3
In-situ4
Fair
4
Pumpable
Excellent
10
Unpumpable
Excellent
14
Cost/ton
Reagent
Labor & per diem
Equipment rental
Used drums @
$11 /drum
Mobilization/demobil-
ization
Cost of treatment
processes
Profit and overhead
(30%)
TOTAL COST/TON
$24.46
(9%)5
61.09
(23%)
44.43
(17%)
57.69
(21%)
18.76
7%
$206.38
61.91
(23%)
$248.29
$21.27
(63%)
1.41
(4%)
1.43
(4%)
1.64
5%
$ 25.75
6.73
(23%)
$ 33.48
$21.27
(53%)
3.97
$10%)
4.07
(10%)
1.48
4%
$ 30.79
9.29
(23%)
$ 40.03
$21.27
(42%)
7.19
(14%)
7.82
(16%)
2.34
5%
$ 38.62
11.59
(23%)
$ 50.21
1 Costs updated from 1983 costs using 1985 ENR Index.
2 Assumed pumpable sludge had a daily throughput of 250 yd3 and the unpumpable
sludge a throughput of 180 ydVday. Remedial action is assumed to be located 200
miles from the nearest equipment.
3 Assumed 49 gallons of untreated waste per drum and a processing rate of 4.5 drums
per hour.
4 Assumed wastes would be mixed by backhoe with a lagoon and left there. Remedial
Action is located 200 miles from its nearest equipment
5 Percent of total cost/ton for that alternative.
5/93
12
-------
IMMOBILIZATION
Sor bents
General Description
Sorbents include a variety of natural and synthetic solid materials that are used to
eliminate free liquid and improve the handling characteristics of wastes. Commonly
used natural sorbent materials include flyash, kiln dust, vermiculite, and bentonite.
Synthetic sorbent materials include activated carbon, which sorbs dissolved organics;
Hazorb (product of Dow Chemical), which sorbs water and organics; and Locksorb
(product of Radecca Corp.), which is reportedly effective for all emulsions (Cullinane
and Jones, 1985).
Applications/Limitations
Sorbents are widely used to remove free liquid and improve waste handling. Some
sorbents have been used to limit the escape of volatile organic compounds. They
may also be useful in waste containment when they modify the chemical environment
and maintain the pH and redox potential to limit the solubility of wastes (Cullinane
and Jones, 1985). Although sorbents prevent drainage of free water, they do not
necessarily prevent leaching of waste constituents and secondary containment is
generally required.
Implementation Considerations
The quantity of sorbent material necessary for removing free liquid varies widely
depending on the nature of the liquid phase, the solids content of the waste, the
moisture level in the sorbent, and the availability of any chemical reactions that take
up liquids during reaction. It is generally necessary to determine the quantity of
sorbent needed on a case-specific basis. Equipment requirements for addition and
mixing of sorbents are simple.
Thermoplastic Solidification
General Description
Thermoplastic solidification involves sealing wastes in a matrix such as asphalt
bitumen, paraffin, or polyethylene. The waste is dried, heated, and dispensed
through a heated plastic matrix. The mixture is then cooled to form a rigid but
deformable solid. Bitumen solidification is the most widely used of the thermoplastic
techniques.
Applications/Limitations
Thermoplastic solidification involving the use of an asphalt binder is most suitable for
heavy metal or electroplating wastes. Relative to the cement solidification, the
5/93 13
-------
IMMOBILIZATION
increase in volume is significantly less and the rate of leaching significantly lower.
Also, thermoplastics are little affected by either water or microbial attack.
There are a number of waste types that are incompatible with thermoplastic
solidification. Oxidizers such as perchlorates or nitrates can react with many of the
solidification materials to cause an explosion. Some solvents and greases can cause
asphalt materials to soften and never become rigid. Xylene and toluene diffuse quite
rapidly through asphalt. Salts that partially dehydrate at elevated temperatures can
be a problem. Sodium sulfate hydrate, for example, will lose some water during
asphalt incorporation, and if the waste asphalt mix containing the partially dehydrated
salt is soaked in water, the mass will swell and crack due to rehydration. This can
be avoided by eliminating easily dehydrated salts or coating the outside of the
waste/asphalt mass with pure asphalt. Chelating and complexing agents (cyanides
and ammonium) can cause problems with containment of heavy metals (Cullinane and
Jones, 1985).
High equipment and energy costs are principal disadvantages of thermoplastic
solidification. Another problem is that the plasticity of the matrix-waste mixture
generally requires that containers be provided for transportation and disposal of
materials, which greatly increases the cost.
Certain wastes, such as tetraborates and iron and aluminum salts, can cause
premature solidification and plug up the mixing machinery (USEPA, 1982b).
Implementation Considerations
Thermoplastic solidification requires specialty equipment and highly trained operators
to heat and mix the wastes and solidifier. The common range of operating
temperatures is 130°-230°C. The energy intensity of the operation is increased by
the requirement that the wastes be thoroughly dried before solidification.
Costs
Cost data for thermoplastic solidification outside of the nuclear industry is not readily
available. Wernen and Pfleudern Corporation has developed an asphalt binder-based
process called the Volume Reduction and Solidification System; solidification costs
for nonradioactive materials are estimated at $20-$70 per ton. This cost includes
secondary containment but not final transport and disposal (Doyle, 1980).
5/93 14
-------
IMMOBILIZATION
Surface Microencapsulation
General Description
Surface encapsulation describes those methods that physically microencapsulate waste
by sealing them in an organic binder or resin. Surface encapsulation can be
accomplished using a variety of approaches. Three methods which have been the
subject of considerable research are described briefly below.
One process developed by Environmental Protection Polymers involves the use of 1,2-
polybutadiene and polyethylene to produce a microencapsulated waste block onto
which a high-density polyethylene (HDPE) jacket is fused. The 1,2-polybutadiene is
mixed with particulated waste which yields, after solvent evaporation, free-flowing,
dry, resin-coated particulates. The resulting polymers are resistant to oxidative and
hydrolytic degradation and to permeation by water. The next step involves formation
of a block of the polybutadiene/waste mixture. Powdered, HDPE is grafted
chemically onto the polymer backbone to provide a final matrix with ductile qualities.
Various combinations of the two resins (polybutadiene and polyethylene) permit
tailoring of the matrix's mechanical properties without reduction of system stability
when exposed to severe chemical stress. In the final step, a 1A-inch-thick HDPE
jacket is mechanically and chemically locked to the surface of the microencapsulated
waste (Lubowitz and Wiles, 1981).
Another encapsulation method developed by Environmental Protection Polymers
involves a much simpler approach. Contaminated soils or sludges are loaded into an
HDPE overpack. A portable welding apparatus developed by Environmental
Protection Polymers is then used to spin weld a lid onto the container, thereby
forming a seam-free encapsulate.
A third surface encapsulation method involves use of an organic binder to seal a
cement-solidification mass. United States Gypsum Company manufactures a product
called Envirostone Cement, which is a special blend of high-grade polymer modified-
gypsum cement. Emulsifiers and ion-exchange resins may be added along with the
gypsum cement, which hydrates to form a free-standing mass. A proprietary organic
binder is used to seal the solidified mass (United States Gypsum Co., 1982). The
process can be used to stabilize both organic and inorganic wastes. It has been shown
to effectively immobilize waste oil present at concentrations as high as 36 volume
percent (Clark, Colombo, and Neilson, 1982). The volume of waste is smaller than
that obtained with cement solidification alone.
Applications/Limitations
Current research shows that the major advantage of encapsulation processes is that the
waste material is completely isolated from leaching solutions. These methods can be
used for both organic and inorganic waste constituents. However, each of the
5/93 15
-------
IMMOBILIZATION
available encapsulation processes are quite unique and the feasibility must be
determined on a case-specific basis.
Other advantages associated with hazardous waste encapsulation include (USEPA,
1982b):
• The cubic and cylindrical encapsulates allow for efficient space use during
transport, storage, and disposal
• The hazard of accidental spills during transport is eliminated
• Materials used for encapsulation are commercially available, very stable
chemically, nonbiodegradable, mechanically tough, and flexible
• Encapsulated waste materials can withstand the mechanical and chemical
stresses of a wide range of disposal schemes (landfill, disposal in salt
formations, and ocean disposal).
The major disadvantages associated with encapsulation techniques include:
• Binding resins required for agglomeration/encapsulation (HDPE and
polybutadiene) are relatively expensive
• The processes are energy intensive and relatively costly
• Skilled labor is required to operate molding and fusing equipment.
Costs
Environmental Protection Polymers has estimated that the cost of the
polybutadiene/HDPE microencapsulation method will be approximately $90/ton.
Encapsulation in the seam-free HDPE overpack is approximately $50-$70 for an 80-
gallon drum load (Lubowitz, H., Environmental Protection Polymers, personal
communication,October 13 and 14, 1983).
Vitrification
General Description
Vitrification of wastes involves combining the wastes with molten glass at a
temperature of 1,350°C or greater. However, the encapsulation might be done at
temperatures significantly below 1,350°C (a simple glass polymer such as boric acid
can be poured at 850°C). This melt is then cooled into a stable, noncrystalline solid
(USEPA, 1982b).
5/93 16
-------
IMMOBILIZATION
Applications/Limitations
This process is quite costly and has been restricted to radioactive or very highly toxic
wastes. To be considered for vitrification, the wastes should be either stable or
totally destroyed at the process temperature.
Of all the common solidification methods, vitrification offers the greatest degree of
containment. Most resultant solids have an extremely low leach rate. Some glasses,
such as borate-based glasses, have high leach rates and exhibit some water solubility.
The high energy demand and requirements for specialized equipment and trained
personnel greatly limit the use of this method.
Implementation Considerations
Vitrification of wastes is an extremely energy-intensive operation and requires
sophisticated machinery and highly trained personnel.
Cost
No cost information was available for vitrification.
Technology Selection/Evaluation
Evaluation of the technical feasibility and effectiveness of stabilization/solidification
methods must be determined on a case-by-case basis. Commercial firms specializing
in these processes should be consulted whenever solidification/stabilization is being
considered. Samples of the solidified product will need to be subjected to extensive
leaching tests unless a reliable, effective means of secondary containment is to be
used. It should be noted that secondary containment is recommended with most of
the previously described methods (except microencapsulation and glassification for
some waste types). Similarly, where the end product is intended to be a monolithic
block, samples must be subjected to compressive strength tests.
Solidification/stabilization methods range from those that use simple, safe, readily
available equipment (cement and most silicate-based processes) to those that require
highly sophisticated, costly, and specialized equipment (e.g., glassification and
thermoplastic techniques). Use of these high technology processes should be limited
to wastes that cannot be treated cost-effectively using any other methods. Regardless
of the simplicity of some of the equipment, professionals trained in these processes
should be consulted because formulations including proprietary additives are very
waste specific.
5/93 17
-------
IMMOBILIZATION
Immobilization
Immobilization methods are designed to render contaminants insoluble and prevent leaching
of the contaminants from the soil matrix and their movement from the area of contamination.
Little is currently known about the effectiveness and reliability of immobilization techniques.
Innovative Immobilization Technologies
Immobilization methods that are currently being investigated include precipitation, chelation,
and polymerization.
Precipitation is the most promising method for immobilizing dissolved metals such as lead,
cadmium, zinc, and iron. Some forms of arsenic, chromium, mercury, and some organic
fatty acids can also be treated by precipitation (Huibregtse and Kastman, 1979). All of the
divalent metal cations can be precipitated using sulfide, phosphate, hydroxide, or carbonate.
However, the solubility product and the stability of the metal complexes vary. Because of
the low solubility product of sulfides and the stability of the metal sulfide over a broad pH
range, sulfide precipitation looks most promising. The remaining anions decrease in
effectiveness in the following order: phosphate > hydroxide > carbonate. Metal carbonates
and hydroxides are stable only over a narrow pH range and the optimum pH range varies for
different metals. Precipitation of the metal as the metal phosphate may require very high
concentrations of orthophosphate because calcium and other naturally occurring soil cations
present in high concentrations will precipitate first.
Sodium sulfate used in conjunction with sodium hydroxide has shown widespread
applicability for precipitation of metals. Precipitation takes place at a neutral or slightly
alkaline pH. Resolubilization of sulfides is low. Addition of sodium hydroxide minimizes
the formation of hydrogen sulfide gas by ensuring an alkaline pH. Experiments with sulfide
precipitation of zinc indicate that a high residual of unreacted sulfide may remain in solution.
As with other in situ techniques, precipitation is most applicable to sites with sand or coarse
silt strata. Disadvantages include the injection of a potential groundwater pollutant, the
potential for formation of toxic gases (in the case of sulfide treatment), the potential for
clogging soil pore space, and the possibility of precipitate resolubilization.
The use of chelating agents may also be a very effective means of immobilizing metals,
although considerable research is needed in this area. Depending on the specific chelating
agent, stable metal chelates may be highly mobile or may be strongly sorbed to the soil.
Tetran is an example of a chelating agent that is strongly sorbed to clay in soils (USEPA,
1984a).
A third method for immobilizing metals applies specifically to chromium and selenium.
These metals can be present in the highly mobile, hexavalent state but can be reduced to less
mobile Cr (III) and Se (IV) by addition of ferrous sulfate. Arsenic exists in soils as either
arsenate, As (V), or as arsenite, As (III), the more toxic and soluble form. Arsenic can be
5/93 18
-------
IMMOBILIZATION
effectively immobilized by oxidizing As (III) to As (IV) and treating the As (IV) with ferrous
sulfate to form highly insoluble FeAsO4.
Polymerization involves injection of a catalyst into a groundwater plume to cause
polymerization of an organic monomer (e.g., styrene, vinyl chloride, isoprene, methyl
methacrylate, and acrylonitrile). The polymerization reaction transforms the once fluid
substance into a gel-like, nonmobile mass. In situ polymerization is a technique most suited
for groundwater cleanup following land spills or underground leaks of pure monomer.
Applications for uncontrolled hazardous waste sites are very limited. Major disadvantages
include very limited application and difficulty of initiating sufficient contact of the catalyst
with the dispersed monomer (Huibregtse and Kastman, 1979). In situ polymerization was
successfully performed to remedy an acrylate monomer leak, in which 4,200 gallons of
acrylate monomer leaked from a corroded underground pipeline into a glacial sand and gravel
layer. Soil borings indicated that as much as 90 percent of the monomer had been
polymerized by injection of a catalyst, activator, and wetting agent (Williams, 1982).
In situ treatment of a leachate plume using precipitation or polymerization techniques
probably has limited application. Problems associated with these techniques include:
• Need for numerous, closely spaced injection wells even in coarse-grained deposits
because the action of precipitation or polymerization will lower hydraulic
conductivities near injection wells and reduce treatment effectiveness
• Contaminants are not removed from the aquifer or some chemical reactions can be
reversed, allowing contaminants to again migrate with groundwater flow
• Injection of a potential groundwater pollutant or the formation of toxic by-products.
Therefore, prior to the application of an in situ precipitation or polymerization technique at
a hazardous waste site, thorough laboratory- and pilot-scale testing should be conducted to
determine deleterious effects and ensure complete precipitation or polymerization of the
chemical compounds.
Solidification methods used for chemical soil consolidation can also immobilize contaminants.
Solidification and stabilization techniques are assessed in terms of their applicability for in
situ treatment of landfilled wastes in Guide to the Disposal of Chemically Stabilized and
Solidified Wastes (USEPA, 1982). The assessment concluded that most work with these
techniques has not involved in situ treatment. Most techniques are not applicable to
hazardous waste sites, and most of the techniques involve a thorough mixing of the
solidifying agent and the waste (Truett, Holberger, and Sanning, 1982). Injection of silicate
gel may be feasible to immobilize subsurface contaminants, but may negatively impact
groundwater quality (Truett, Holberger, and Sanning, 1982).
5/93 19
-------
IMMOBILIZATION
MONITORING
Wastestream characterization prior to selecting any treatment technology is essential. Also essential
is knowing the characteristics of these streams following treatment. Therefore, sampling plans must
be prepared which will identify that a technology has met its treatment objectives. Because
solidification/stabilization treatments are designed to immobilize contaminants, it is important to test
the solidified product to determine whether wastes are indeed immobilized. Therefore, representative
product samples must be collected. These samples are collected in cylindrical waxed cardboard or
PVC forms following a batch mix, and then are allowed to cure. The length of curing time can
affect test results. In the Chemfix process, a curing time of 28 days was used prior to conducting
tests.
Tests performed to assess the effectiveness of solidification/stabilization treatments may be classified
as physical tests or chemical tests. Physical tests are performed to quantify physical changes to the
treated material and include such things as material bulk density and moisture content. Some
common physical tests include those listed in TABLE 1. A more extensive list of physical and
chemical tests may be found in Stabilization/Solidification of CERCLA and RCRA Wastes (EPA
document number 625/6-89/022). The unconfined compressive strength of a solidified material is
considered to be satisfactory when it is a minimum of 50 psi according to USEPA OSWER Directive
No. 9437.00-2A. Interpretation of results from other physical tests have not been standardized.
Chemical tests are performed to evaluate the stability of the treated material within the environment.
Therefore, sample preparations that specify leaching procedures can yield important data regarding
contaminant mobility. TABLE 2 shows several of the leaching procedures that are used to evaluate
contaminant mobility. The Toxicity Characteristic Leaching Procedure (TCLP) was specified to
replace the Extraction Procedure Toxicity Test (EP Tox) as the criterion for defining whether a waste
is hazardous. The intent was to use a procedure that would yield "worst case" conditions for waste
leaching. However, several studies have shown that TCLP leaching of cement-based waste forms
may not necessarily yield maximum concentrations. Multiple extraction tests, such as the Monofill
Waste Extraction Procedure (MWEP) or the Multiple Extraction Procedure (MEP), may be needed
to assess maximum leachate concentrations under different pH conditions.
The short-term environmental impact of stabilizing most amenable wastes is small, but long-term
reliability is not well known. Leachate that may be produced as a result of the curing process should
be collected and analyzed to determine the necessity for treatment before disposal. The volume of
leachate is usually minimal. Gas monitoring, collection, and treatment may be necessary with wastes
containing ammonium ions or volatile organics. The alkalinity of cement drives off ammonium ions
as ammonia gas. The heat generated by the curing or setting of the stabilized product can drive off
organic volatiles.
Because the long-term effects of this technology have not been documented, site monitoring by means
of leachate collection and institutional controls may be warranted.
5/93 20
-------
IMMOBILIZATION
APPENDIX I
ADVANTAGES AND DISADVANTAGES OF CEMENTS AND POZZOLANS
Advantages
Disadvantages
CEMENTS
Inexpensive and plentiful raw materials.
High strengths and low permeabilities are
possible.
Technology and equipment are commonplace.
System is tolerant of most chemical
variations.
Dewatering is not necessary.
POZZOLANS
Very inexpensive raw materials.
High strengths and low permeabilities are
possible.
Reactions are well understood.
Dewatering is not necessary.
Large quantities of cement often required.
Ultimate leachability not guaranteed.
Susceptible to borates, sulphates, and acids.
Handling of lime can be difficult.
Susceptible to acids, and sugars.
Ultimate leachability not guaranteed.
Source: USEPA, 1980
5/93
21
-------
IMMOBILIZATION
APPENDIX II
TECHNOLOGY SUMMARY
Waste Type: Soils and Sludges
Technology: Stabilization/Solidification
Characteristics
Impacting Process
Feasibility
Sodium arsenate, berates,
phosphates, iodates, sulfide, and
carbohydrates
Sulfates
Volatile organics
Presence of leachable metals
Phenol concentration greater than
5%
Presence of coal or lignite
Organic content should be no
greater than 20-45 % by weight
when using cement-based
technologies
Semivolatile organics
> 10,000 ppm
PAHs
> 10,000 ppm
Wastes with less than 15% solids
Reason for Potential Impact
Retard setting and curing and weaken
strength of final product.
Retard setting and cause swelling and
sp ailing.
Volatiles not effectively immobilized.
Driven off by heat of reaction.
Sludges containing volatile organics can be
treated using a heated extruder/evaporator to
evaporate free water and VOCs and mixing
with asphalt. VOCs with flashpoint below
350°F, thermally unstable materials, solvents
in sufficient concentrations to soften the
asphalt, and highly reactive materials require
pretreatment.
Effectiveness of stabilization methods may
vary.
Results in marked decreases in compressive
strength
Coals and lignite can cause problems with
setting, curing, and strength of the end
product.
Organics interfere with bonding of waste
materials.
Organics interfere with bonding of waste
materials.
Large volumes of cement or other reagents
required, greatly increasing the volume and
weight of the end product. Waste may
require reconstitution with water to prepare
waste/reagent mix.
Data
Collection
Requirements
Bench-scale testing
Analysis for sulfate
Analysis for volatile
organics, bench-scale testing
Analysis for priority
pollutants, bench-scale
testing
Analysis for phenols
Core sampling with specific
analysis for coal
Analysis for volatile solids,
total organic carbon
Analysis for semivolatile
organics, PAHs
Analysis for total solids and
suspended solids
5/93
22
-------
IMMOBILIZATION
TECHNOLOGY SUMMARY
Waste Type: Soils and Sludges
Technology: Stabilization/Solidification
Characteristics
Impacting Process
Feasibility
Oil and grease should be < 10%
when using cement-based
technology
Fine particle size
Halides
Soluble salts of manganese, tin,
zinc, copper, and lead
Cyanides
>3,000ppm
Reason for Potential Impact
Weaken bonds between waste particles and
cement by coating the particles
Insoluble material passing through a No. 200
mesh sieve can delay setting and curing.
Small particles can also coat larger particles,
weakening bonds between particles and
cement or other reagents. Particle size < 14
inch in diameter not suitable.
May retard setting; easily leached.
Reduce physical strength of final product;
cause large variations in setting time; reduce
dimensional stability of the cured matrix,
thereby increasing teachability potential.
Cyanides interfere with bonding of waste
materials
Data
Collection
Requirements
Analysis for oil and grease
Soil particle size distribution
Analysis for total halides
Analysis for inorganic salts
Analysis for cyanides
5/93
23
-------
Section 13
-------
DISPOSAL OPTIONS
STUDENT PERFORMANCE OBJECTIVES:
At the conclusion of this unit, participants will be able to:
• Briefly describe the federal regulations covering hazardous waste land
disposal
• List at least two sources of information about EPA Land Disposal Restrictions
• Briefly describe the steps needed to complete a waste characterization record
for shipping hazardous waste
• List at least three alternative hazardous waste disposal methods.
5/93
-------
/VOTES
HOW DID WE GET
WHERE WE ARE NOW ?
• Resource Conservation and
Recovery Act (RCRA) of 1976
• Hazardous and Solid Waste
Amendments (HSWA) of 1984
LAND DISPOSAL
• EPA defined land disposal to include, but not
be limited to, any placement of hazardous waste
in:
Landfills
Surface impoundments
Waste piles
Injection wells
Land treatment facilities
Salt domes or salt bed formations
Underground mines or caves
Concrete vaults or bunkers intended for
disposal purposes
LANDMARK LAND DISPOSAL DATES
• November 1986 - Spent solvents and dioxins
• July 1987 - "California List" liquid wastes
Cyanides
Heavy metals
Polychlorinated biphenyls (PCBs)
Halogenated organic compounds (HOCs)
Acids with pH ^ 2
5/93
Disposal Options
page.1
-------
NOTES
LANDBANS
• August 1988-First third
• June 1989-Second third
• May 1990-Third third
DO YOU HAVE A HAZARDOUS WASTE?
• Characteristic wastes (D001 - D043)
Ignitable(DOOI)
Corrosive (D002)
Reactive (D003)
Heavy metals (D004 - D011)
Pesticides (D012-D017)
Newly listed organics (D018 - D043)
DO YOU HAVE A HAZARDOUS WASTE?
Listed wastes
Spent solvents (F001 - F005)
Production by-products "K"
Poisons "P"
Unused products "U"
Disposal Options
page 2
5/93
-------
NOTES
DO YOU HAVE A HAZARDOUS WASTE?
• Other listed wastes
Metal treating or electroplating
wastes (F006-F019)
Wastes containing dioxin
(F023, F026 - F028)
Leachate (F039)
TREATMENT STANDARDS
• Concentration-based
• Required technologies
WASTEWATER VERSUS
NONWASTEWATER
• Wastewater definition
Aqueous waste
< i% total suspended solids (TSS)
< 1% total organic carbon (TOC)
• Nonwastewater definition
Any waste of treatment residue
not meeting the above definition
5/93
Disposal Options
page 3
-------
NOTES
CONCENTRATION-BASED
TREATMENT STANDARD
• Based on Best Demonstrated Available
Technology (BOAT)
• Hazardous constituents in treatment
residue
• Technology example:
Incinerator ash
Incinerator scrubber water
CONSTITUENT CONCENTRATIONS IN WASTES (CCW)
Regulated Hazardous Wastewaters Nonwastewater
Waste Code Constituent Cone, (mg/l) Cone, (mg/l)
F001-F005 1,1,2-Trichloroethane 0.03
(Spent Solvents)
Benzene 0.07
7.6
3.7
TREATMENT STANDARD BASED ON
REQUIRED TECHNOLOGIES
• Treatment or disposal method specified
for waste
• Impossible, to establish concentration
limits
• Analytical results difficult to reproduce
Disposal Options
page 4
5/93
-------
NOTES
TECHNOLOGY-BASED STANDARDS
Waste Code Waste Description Wastewaters Nonwastewaters
and/or Treatment Technology
Subdivision Code
F005 2-Ethoxyethanol BIODGorlNCIN INCIN
K113 Toluenediamine CARBN or INCIN FSUBS or INCIN
0002 Acid or alkaline DEACT DEACT
TREATMENT STANDARD BASED ON
REQUIRED TECHNOLOGIES
• Examples of available technologies
Alkaline chlorination
Carbon adsorption
Fuel substitution
Incineration
Stabilization
TREATMENT, STORAGE, AND
DISPOSAL FACILITIES (TSD)
• Treatments available
Secure landfill
Incineration
Stabilization
Deepwell injection
Distillation (solvent recycling)
Metals reclamation
5/93
Disposal Options
page 6
-------
NOTES
TREATMENT, STORAGE, AND
DISPOSAL FACILITIES (TSD)
• Approval process
Representative sample
Profile sheet
Analytical information
Land disposal restriction (LDR) forms
State approval
Approval fees
Contract
TREATMENT, STORAGE, AND
DISPOSAL FACILITIES (TSD)
Shipping requirements per HM-181
Selection of carrier
Manifest
Labeling requirements
Packaging requirements
Notification & certification
TREATMENT, STORAGE, AND
DISPOSAL FACILITIES (TSD)
• Shipping containers for solids
Roll-off boxes (bulk)
Drums
• Shipping containers for liquids and sludges
Tankers (bulk)
Vacuum tankers (bulk)
Tote bins (200 - 300 gals.)
Drums (steel, plastic)
Disposal Options
pages
5/93
-------
/VOTES
TREATMENT, STORAGE, AND
DISPOSAL FACILITIES (TSD)
• Special containers
Lab-packs
Burnable containers for incineration
THESE STATES HAVE AT LEAST ONE
HAZARDOUS WASTE INCINERATOR
THESE STATES HAVE AT LEAST ONE
HAZARDOUS WASTE LANDFILL
5/93
Disposal Options
page 7
-------
DISPOSAL OPTIONS
Offsite Disposal
General Description
This section describes the major factors that must be considered when selecting an
offsite disposal facility and preparing wastes for offsite transport. Offsite disposal,
as described in this section, includes landfilling and incineration.
Applications/Limitations
Determining the feasibility of offsite disposal requires knowledge of Resource
Conservation Recovery Act (RCRA) regulations (40 CFR Parts 261-265) and other
regulations developed by state governments. RCRA manifest requirements, under 40
CFR Parts 262 and 263, must be complied with for all wastes that are shipped
offsite. In addition, the waste generator (or other responsible party, when the
generator is unknown) must comply with RCRA manifest requirements under 40 CFR
Parts 262 and 263, and the generator should comply with applicable hazardous waste
generator requirements under 40 CFR Part 262. In addition, the generator must
comply with all applicable federal and state environmental and public health statutes.
Under 40 CFR 264.12, RCRA storage and disposal facilities are required to notify
the generator, in writing, that they are capable of managing the wastes. The
generator must keep a copy of this written notification on file as part of the operating
record.
Offsite Landfilling
Landfilling of hazardous materials is becoming increasingly difficult and more expensive due
to steadily growing regulatory control of this technology. Therefore, wastes that are
amenable to treatment or incineration should be segregated from wastes for which no
treatment alternative is known. Landfilling should usually be regarded as the least attractive
alternative at a site cleanup action.
Landfilling costs are approximately $240/ton for highly toxic wastes (e.g., high levels of
chlorinated hydrocarbons), $120/ton for ignitable materials (40 CFR Part 264.312 must be
complied with), $85/ton for most industrial sludges, and $40-$50/ton for municipal treatment
sludges.
Incineration
The most important factors that a treatment facility considers in determining the suitability
of wastes for incineration include BTU content of the waste, viscosity, water content, halogen
content and ash content. Many incineration facilities' permit conditions specify a minimum
5/93
-------
DISPOSAL OPTIONS
acceptable BTU content. The minimum acceptable BTU is generally not less than about
5,000 BTU/lb because at this heating value, the incineration process can often be self
sustaining and require no auxiliary fuel. High water content in a waste tends to reduce the
heating value; therefore, many facilities will specify a maximum allowable water content.
Certain incinerators are not equipped to handle highly viscous or solid wastes, and this may
be yet another criterion that facilities use to accept or reject a waste load.
EPA regulations (under RCRA) for hazardous waste incineration require that paniculate
emissions be no more than 180 mg/Nm3 and that hydrogen chloride removal efficiency from
the exhaust gas be no less than 99 percent. Trial burns are conducted prior to issuance of
a permit to determine the maximum ash and chlorine content that a waste can contain in
order to meet these requirements. Thus, the facility is likely to have maximum limits for
halogen content and ash. Incineration of PCBs and low-level radioactive wastes requires
special permits and there are only a limited number of facilities permitted to handle these
wastes.
IMPLEMENTATION
Preparation of Wastes for Offsite Treatment/Disposal
Where drums or multiple impoundments are present, it is often most cost-effective to
consolidate their contents in a tank truck. Compatibility testing should be performed prior
to bulking wastes for offsite transport to ensure that consolidation will not result in
incompatible waste reactions or in large volumes of waste that are unacceptable for offsite
disposal. Compatibility testing refers to simple, rapid, and cost-effective testing procedures
that are used to segregate wastes into broad categories. By identifying broad waste
categories, compatible waste types can be safely bulked onsite without risk of fire, explosion,
or release of toxic gases, and disposal options can be determined without an exhaustive
analysis of each waste type.
Compatibility testing protocols have been developed by a number of cleanup contractors and
generators. Often, however, the procedures must be tailored to meet the testing requirements
of prospective treatment/disposal facilities. The Chemical Manufacturers Association (CMA,
1982) has developed a compatibility testing protocol that has been used at a number of sites.
Based on the CMA protocol, wastes can be segregated into the following broad waste
categories:
• Liquids
- Radioactive
- Peroxides and oxidizing agents
- Reducing agents
- Water-reactive compounds
5/93 10
-------
DISPOSAL OPTIONS
• Water insolubles
- Low halogen, low PCB
- Mixed halogen, high PCB
- High halogen, low PCB
• Acids
- Strong (pH < 2)
- Weak (pH 7-12), with or without cyanides or sulfides
• Bases
- Strong (pH > 12), with and without cyanides or sulfides
- Weak (pH 7-12), with and without cyanides or sulfides
• Solids
- Radioactive
- Nonradioactive.
Testing to determine gross halogen content is sometimes eliminated if all insoluble wastes are
to be incinerated at a facility capable of handling chlorinated organics. However, testing for
PCBs is required regardless of the need for testing other halogenated compounds.
The CMA protocol also requires that small samples of wastes that are intended to be bulked
are mixed together. Visual observations are then made for precipitation, temperature
changes, or phase separation.
There are some differences between the CMA compatibility protocol and the protocol used
by some cleanup contractors. One commonly used procedure is to conduct flammability and
ignitability tests on a drum-by-drum or waste-by-waste basis for both liquid and solid drums.
CMA, on the other hand, recommends that these tests be performed on composite samples
before bulking, because these tests require more costly and time-consuming analysis (torch
test and closed cup flame test). Another common practice is to conduct further testing on
samples from drums containing solids. These tests may include water reactivity, water
solubility, pH, and the presence of oxidizers. In general, the decision to perform these
analyses on each waste rather than on a composite sample (prior to bulking) is made based
on the number of drums and the types of wastes known to be present onsite.
Hatayama et al. (1980a, 1980b) have also provided guidance on waste incompatibilities that
can be useful during the waste consolidation process. These researchers have developed a
hazardous waste compatibility protocol that allows the user to evaluate potential adverse
reactions for binary combinations of hazardous wastes. Binary waste combinations are
evaluated in terms of the following adverse reactions: heat generation from a chemical
5/93 11
-------
DISPOSAL OPTIONS
reaction, fire, toxic gas generation, flammable gas generation, explosion, and violent
polymerization of a toxic substance.
A detailed waste analysis is generally required before a waste is accepted by a
treatment/disposal facility. TABLE 1 specifies the types of analyses that are typically
required before a waste can be considered for offsite disposal at a particular facility.
However, requirements vary considerably depending upon the facility permits, state
regulations, physical state of the wastes, and the final disposal option that is selected.
Onsite pretreatment of wastes may be required to make them acceptable for offsite transport
or to meet the requirements of an incineration or disposal facility. For incineration or land
disposal facilities, pretreatment will likely be limited to the following:
• Acid-base neutralization (land disposal and incineration)
• Metal precipitation/solidification (land disposal)
• Hypochlorite oxidation of cyanide and sulfide (land disposal and incineration)
• Flash point reduction (land disposal)
• Removal of free liquids by addition of soils, lime, fly ash, polymers, or other
materials that remove free water (land disposal).
Transportation
The transportation of hazardous wastes is regulated by the U.S. Department of Transportation
(DOT), the Environmental Protection Agency, the states, and, in some instances, by local
ordinances and codes. In addition, more stringent federal regulations also govern the
transportation and disposal of highly toxic and hazardous materials such as PCBs and
radioactive wastes. Applicable DOT regulations include:
• Department of Transportation 49 CFR, Parts 172-179
• Department of Transportation 49 CFR, Part 2387 (46 FR 30974, 47073)
• Department of Transportation DOT-E 8876.
The EPA regulations under RCRA (40 CFR Parts 262 and 263) adopt DOT regulations
pertaining to labeling, placarding, packaging, and spill reporting. These regulations also
impose certain additional requirements for compliance with the manifest system and record-
keeping.
Vehicles for offsite transport of hazardous wastes must be DOT approved and must display
the proper DOT placard. Liquid wastes must be hauled in tanker trucks that meet certain
requirements and specifications for the waste types. Contaminated soils are hauled in box
5/93 12
-------
DISPOSAL OPTIONS
trailers and drums in box trailers or flatbed trucks. The trucks should be lined with plastic
and/or absorbent materials.
Before a vehicle is allowed to leave the site, it should be rinsed or scrubbed to remove
contaminants. Both bulk liquid containers and box trailers should be checked for proper
placarding, cleanliness, tractor-to-trailer hitch, and excess waste levels. Bulk liquid
containers should also be checked for proper venting, closed valve positions, and secured
hatches. Box trailers should be checked to ensure correct liner installation, secured cover
tarpaulin, and locked lift gate.
TABLE 1
POTENTIAL ANALYTICAL REQUIREMENTS FOR DISPOSAL
Physical State
Physical state at 70°F
Number of layers
Free liquids (percent by volume)
pH
Specific gravity
Flash point
Viscosity
Waste Composition
EP toxic metals (arsenic, barium, cadmium, chromium, lead, mercury, selenium, and
silver)
EP toxic pesticides (endrin, lindane, methoxychlor, toxophene, 2,4-D, 2,4,5-TP)
Hydrocarbon composition (must account for 100 percent)
Organochlorine
Sulfur
Cyanide
PCB content
Hazardous Characteristics
Reactive (pyrophoric or shock sensitive)
Explosive
Water reactive
Radioactive
Ignitable
5/93 13
-------
DISPOSAL OPTIONS
Selection/Evaluation Considerations
Excavation and removal can almost totally eliminate the contamination at a site and the need
for long-term monitoring. Once excavation is begun, the time to achieve beneficial results
can be short relative to such alternatives as in situ treatment, subsurface drains, and, in some
instances, pumping. Excavation and removal can be used in combination with almost any
other remedial technologies.
The biggest drawbacks with excavation, removal, and offsite disposal are associated with
worker safety, short-term impacts, cost, and institutional aspects. Where highly hazardous
or toxic materials are present, excavation can pose a substantial risk to worker safety. Short-
term impacts such as fugitive dust emissions, toxic gases, and contaminated runoff are
frequently a major concern, although mitigative measures can be taken. Costs associated
with offsite disposal are high and frequently result in exclusion of complete excavation and
removal as a cost-effective alternative. The location of a RCRA-approved landfill or
incinerator also has a substantial impact on cost.
Implications of RCRA
Subtitle C of RCRA is designed to provide comprehensive regulation of hazardous wastes.
Intended to protect the environment, regulations under the act will place added waste
management responsibilities on organizations. RCRA will affect the generation, storage,
treatment, transport, and disposal of hazardous wastes. These provisions are covered under
Sections 3001 to 3010 of the act. Hazardous wastes generated from spills and abandoned
hazardous waste sites are affected as well.
Code of Federal Regulations
Sections 3001-3010 of RCRA provide the basis for regulations. Hazardous waste
management is regulated under the Code of Federal Regulations (CFR), Title 40 - Protection
of the Environment and Parts 260 through 265 as follows:
1. Part 260: Definitions & General Provisions
2. Part 261: Identification and Listing of Hazardous Waste
3. Part 262: Generation Standards (as Amended)
4. Part 263: Transporter Standards (as Amended)
5. Part 264: Facility Standards
6. Part 265: Interim Status Standards.
5/93 14
-------
DISPOSAL OPTIONS
Regulatory Relationships
40 CFR 260-265 relates to 40 CFR 122-125, Consolidated Permit Regulations administered
by EPA and 49 CFR 100-199, regulating materials transportation under the Hazardous
Materials Transportation Act (HMTA) administered by the DOT.
1. Consolidated Permit Regulations
a. Part 122: Permit Requirements
b. Part 123: State Program Requirements
c. Part 124: Procedures for Decision-makers
d. Part 125: NPDES Amendment
HMTA
a.
Part 172: Hazardous Materials & Communications
b. Pan 173: Shippers General Requirements
RCRA
a. The relationship between RCRA, the act, and the resulting
regulations can be seen in the following comparisons:
b. RCRA
RCRA
SECTION
(3001)
(3002)
(3003)
40 CFR
261
262
263
SUBJECT
Contains criteria and listing of hazardous wastes. Defines what
is considered to be hazardous for waste generators.
Lists standards and responsibilities applicable to generators of
hazardous wastes. Covers recordkeeping, manifest system, and
reporting requirements.
Lists standards applicable to transporters of hazardous wastes.
Includes recordkeeping, labeling, and coordination with DOT.
5/93
15
-------
DISPOSAL OPTIONS
(3004) 264,265
(3005)
(3006)
122, 124
123
(3007)
(3008)
(3009)
(3010) 45 FR 12746
Lists design and operating standards applicable to owners and
operators of hazardous waste treatment, storage, and disposal
facilities (TSD).
Describes the permit requirements for TSD and related
administrative requirements and procedures.
Gives individual states the responsibility of administering and
enforcing the act by briefly outlining the requirements for
obtaining authorization from EPA and retaining this authority
thereafter.
Provides inspection authority to EPA and state officers for the
collection of samples and filed information. This section also
addresses the extent of confidentiality of information obtained.
Discusses the enforcement actions, civil and criminal penalties,
and fines exacted on violators of the act's requirements. After an
unheeded 30-day allowance for corrective action, a violator may
be assessed a $25,000 fine for each day of continued
noncompliance. Knowingly violating the requirements of the act
can result in the same fine and/or imprisonment for up to one (1)
year upon conviction.
Sets up the EPA regulations as minimal requirements, causing the
states to align with the act.
Requires that hazardous waste generators, transporters, and
owners/operators of TSDs formally notify EPA of all hazardous
waste activities. Federal agencies must also comply with the
notification requirements.
Transporter Standards
40 CFR 263, Transporter Standards (as Amended) relate closely to 49 CFR Parts 100-199
regulating materials transportation under the HMTA. Specifically, 49 CFR 172, Hazardous
Materials Table and Hazardous Materials Communications Regulations, along with 49 CFR
173, Shippers - General Regulations for Shipments and Packaging, relate to 40 CFR 263.
HMTA regulations administered by the DOT do not apply to federal, state, or local
governments carrying hazardous materials as part of a governmental function using
governmental employees, facilities, and vehicles. Also, HMTA highway transportation
regulations generally apply only to interstate commerce; hence, intrastate hazardous material
transportation by highway is not directly regulated. However, the EPA-administered RCRA
5/93
16
-------
DISPOSAL OPTIONS
transporter regulations do apply to (1) all governmental agencies, regardless of function, and
(2) both interstate and intrastate commerce.
Operations Under Regulations
1. Storage and classification
2. Site management
a. Sampling procedures
b. Chain of custody
c. Spill prevention
d. Water and air monitoring
3. Transportation
a. Containerization and handling
b. Labeling
c. Manifesting
d. Shipping
4. Ultimate Disposal
a. Onsite
b. Offsite
5/93 17
-------
DISPOSAL OPTIONS
HAZARDOUS AND SOLID WASTE AMENDMENTS OF 1984
EPA has drafted a rule to amend EPA's existing hazardous waste regulations to reflect the provisions
of the Hazardous and Solid Waste Amendments of 1984 (HSWA), which have immediate or short-
term effects on the regulated community. The rule will be issued in interim final form and will
become effective immediately. In the preamble to the rule, EPA invites public comment on the
regulatory amendments and on the issues raised by the amendments. The following is a summary
of the major regulatory changes:
1. Ban on placement of noncontainerized liquid hazardous waste and nonhazardous
liquids in landfills. The new regulations impose an absolute ban on placement of
bulk of noncontainerized liquid hazardous waste or hazardous waste containing free
liquids in any permitted or interim status landfill effective May 8, 1985. Effective
November 8, 1985, placement of nonhazardous liquids in permitted or interim status
landfills is banned. An owner or operator may obtain an exemption from the ban on
nonhazardous liquids by demonstrating that the only reasonably available disposal
alternative for such liquids is a landfill or unlined surface impoundment that may
already contain hazardous waste, and that disposal in the owner or operator's landfill
will not present a risk of contamination to any underground source of drinking water.
2. Minimum technological requirement for permitted and interim status facilities.
Permits issued after November 8, 1984, for new landfills and surface impoundments
must require two or more liners and a leachate collection system above (for landfills)
and between the liners. These requirements may be necessary to protect human
health and the environment. Variances are available for monofills and for alternative
designs. Interim status landfills and surface impoundments, except for existing units,
must also meet the new technological requirements with respect to waste received
beginning May 8, 1985. New interim status waste pile units must install single liners
with a leachate collection system above the liner.
3. Redefinition of "regulated unit" for purposes of the groundwater monitoring and
response program. General groundwater monitoring and corrective action
requirements of Subpart F of Part 264 apply at the time of permitting to landfills,
surface impoundments, waste piles, and land treatment units that receive hazardous
waste after July 16, 1982. (The former cut-off date was January 26, 1983.)
4. Obligation to institute corrective action at permitted facilities. Any permit issued
after November 8, 1984, must require corrective action for all releases of hazardous
waste or constituents from any solid waste management unit (including inactive units)
regardless of when waste was placed at the unit. When such corrective action does
not occur before permitting, the permit issued to a facility containing solid waste
management units must include a schedule of compliance and an assurance of
financial responsibility for completing corrective action.
5/93 18
-------
DISPOSAL OPTIONS
5. Cleanup beyond a facility's property boundary. The owner or operator of a
permitted facility must institute corrective action beyond the facility boundary where
necessary to protect human health and the environment, unless the owner or operator
shows that he or she is unable to obtain permission to undertake such action on
adjacent property.
6. Elimination of the double-liner variance from the groundwater monitoring and
response program. The new rule deletes the groundwater monitoring waiver
formerly available to landfills, surface impoundments, and waste piles that have a
double liner and are located entirely above the seasonal high water table. The rule
also deletes the groundwater monitoring waiver for waste piles that are located above
the seasonal high water table and have periodic liner inspections.
7. Variance from groundwater monitoring for certain engineered structures. A
groundwater monitoring variance is available to an engineered structure that does not
receive or contain liquid waste, is designed and operated to exclude liquid from
precipitation or other runoff, has multiple leak detection systems built into the inner
and outer layers of containment, is operated and maintained through the end of the
post-closure period, and prevents the migration of hazardous constituents beyond the
outer layer of containment prior to the end of the post-closure care period.
8. Ban on disposal in certain salt dome formations, caves, and underground mines. The
new rule bans placement of bulk or noncontainerized liquid hazardous waste in salt
dome formations, salt bed formations, underground mines, or caves in permitted
facilities. This ban will remain in effect until EPA is able to make a series of
findings and issues a permit for the facility. In addition, interim status facilities are
absolutely prohibited from placing any hazardous waste in the four enumerated
settings. This ban does not apply to the Department of Energy Waste Isolation Pilot
Project in New Mexico.
9. Ban on use of materials mixed with hazardous waste for dust suppression. The new
regulations prohibit the use of waste or used oil or other material that is contaminated
with dioxin or any other hazardous waste (other than a hazardous waste identified
solely on the basis of ignitability) for dust suppression or road treatment.
10. Manifest and destination requirements for small quantity generators. Small quantity
generators generating between 100 and 1,000 kilograms of hazardous waste per
calendar month must either (1) treat, store, or dispose of such waste at a facility with
interim status or a RCRA permit; (2) treat, store, or dispose of such waste at a
facility authorized by a state to manage municipal or industrial solid waste; (3) store
no more than 1,000 kilograms of the waste onsite; or (4) recycle the waste. These
requirements remain in effect until EPA promulgates new standards applicable to
small quantity generators or until March 31, 1986, whichever occurs first. No later
than August 7, 1985, hazardous waste shipped offsite by a small quantity generator
must be accompanied by a copy of the EPA Uniform Hazardous Waste Manifest.
5/93 19
-------
DISPOSAL OPTIONS
11. Variance from preconstruction ban. Current regulations prohibit the construction of
new hazardous waste management facilities without a finally effective RCRA permit.
The new rule exempts from this ban any facility for the incineration of PCBs that has
an EPA approval under TSCA.
12. Permit life. Any permit for a treatment, storage, or disposal facility must be for a
fixed term, not to exceed 10 years. Each permit for a land disposal facility must be
reviewed 5 years after the date of issuance or reissuance and must be modified where
necessary to comply with applicable requirements or to protect human health and the
environment.
13. Authority to add conditions. In deciding whether to issue a permit, EPA must
consider adding additional requirements, beyond those contained in EPA regulations,
where necessary to protect human health and the environment.
14. Extension of interim status to newly regulated units. A facility may qualify for
interim status if it is in existence on the effective date of a statutory or regulatory
change under RCRA that requires the facility to have a permit (e.g., a facility which
treats, stores, or disposes of newly listed hazardous wastes). The facility must also
comply with the other prerequisites specified in the statute (e.g., submission of a Part
A application) to actually obtain interim status.
15. Loss of interim status. Interim status terminates automatically for any facility that
fails to submit a Part B application by a specified deadline. Land disposal facilities
must also certify compliance with applicable groundwater monitoring and financial
responsibility requirements. Application deadlines are November 8, 1985, for land
disposal facilities, November 8, 1986, for incinerators, and November 8, 1988, for
all other facilities.
16. Ban on hazardous waste in certain cement kilns. Any cement kiln located in an
incorporated city with a population greater than 500,000 many not burn hazardous
waste, or any fuel containing a hazardous waste, unless the cement kiln complies with
RCRA regulations applicable to incinerators. The ban is effective until EPA develops
substantive standards for cement kilns burning hazardous waste.
17. Labeling of hazardous waste fuels. Beginning February 6, 1985, any person who
produces, distributes, or markets fuel produced from hazardous waste or containing
hazardous waste must include a warning label on the invoice or bill of sale. The
regulations provide exemptions from the labeling requirement for hazardous waste-
derived petroleum coke and for two types of hazardous waste-derived fuels from
petroleum refining operations.
18. Clarification of household waste exclusion. A resource recovery facility recovering
energy from burning municipal waste is not considered to be managing hazardous
waste as long as the facility (1) receives and burns only household waste and non-
hazardous solid waste from other sources and (2) does not accept hazardous wastes.
5/93 20
-------
DISPOSAL OPTIONS
19. Exposure information and health assessments. Beginning August 8, 1985, Part 8
permit applications for surface impoundments and landfills must be accompanied by
information on the potential for the public to be exposed to hazardous wastes through
releases related to the unit. Owners or operators who submitted Part B applications
prior to November 8, 1984, must submit the required exposure information by
August 8, 1985.
20. Additional criteria and procedures for delisting petitions. In evaluating a delisting
petition, EPA must consider factors including additional constituents other than those
for which the waste was listed if the Administrator has a reasonable basis to believe
that such additional factors could cause the waste to be a hazardous waste. Delisting
petitions must include sufficient information for this determination. The rule also
eliminates EPA's procedure for granting temporary exclusions without notice and
comment.
21. Research and development permits. EPA is authorized to issue permits for research,
development, and demonstration treatment activities for which permit standards have
not been established in the regulations. Permits may be issued independent of the
substantive standards in Parts 264 and 265. EPA may waive or modify its basic
permitting procedures in order to expedite permitting. Permits are issued for 1 year
and may be renewed 3 times.
22. Extension of interim authorization for state programs. Interim authorization under
RCRA now ends on January 26, 1986.
23. Requirement that state programs ensure public availability of information.
Information obtained by authorized states regarding facilities and sites for the
management of hazardous waste must be made available to the public in substantially
the same manner as would be the case if EPA were carrying out the RCRA program
in the state.
24. Requirements effective in authorized states prior to state authorization. Any
requirements or prohibition imposed by HSWA takes effect on the same date in both
authorized and nonauthorized states. The Administrator will carry out such
requirements directly in an authorized state until the state is granted authorization to
do so. A state or local requirement that is more stringent than a requirement in the
new rule will remain in effect.
25. Moving target provision. Under EPA's current regulations, EPA may base its
decision to authorize a state's program on the federal program in effect 1 year prior
to submission of the state's application. HSWA specifically endorses this approach.
For purposes of the new provisions addressed by the codification rule, the "effective
date" under the moving target rule is the date and codification rule that appears in the
Federal Register.
5/93 21
-------
DISPOSAL OPTIONS
26. Conforming amendments to state authorization regulations. The codification rule
adds several new provisions to EPA's regulatory program. States may begin to seek
authorization to implement those provisions in lieu of the federal program. EPA's
state authorization rules will be modified, as needed, to provide requirements for state
programs that parallel the new requirements.
27. Recordkeeping for hazardous waste exports. Any person exporting hazardous waste
must file with EPA, no later than March 1 of each year, a report summarizing types,
quantities, frequency, and ultimate destination of all hazardous waste exported during
the previous year.
28. Waste minimization certification and reporting requirements. Effective September
1, 1985, a generator (except for a small quantity generator) must sign a certification
in the Uniform Hazardous Waste Manifest Form that the generator has a program to
minimize the amount and toxicity of wastes generated and that the generator's
proposed treatment, storage, or disposal method minimizes the threat to human health
and the environment. Generators must submit information regarding such waste
minimization efforts in their biennial report to EPA. Effective September 1, 1985,
any permittee who treats, stores, or disposes of hazardous waste on the premises
where the waste was generated must provide a certification in the written operating
record regarding efforts taken to minimize the amount and toxicity of the generated
wastes.
29. Requirements for new underground storage tanks. Effective May 7, 1985, the new
rule prohibits the installation of any new underground storage tank unless the tank (1)
will prevent releases due to corrosion or structural failure for the operational life of
the tank, (2) is cathodically protected against corrosion, constructed of noncorrosive
material, or designed to prevent releases, and (3) is constructed of material that is
compatible with the substances stored. An exemption from the corrosion protection
requirement is available for tanks that are installed in soils with a resistivity of
12,000 ohm/cm or more. These requirements remain in effect until EPA
promulgates standards for new tanks.
5/93 22
-------
DISPOSAL OPTIONS
APPENDIX I
TABLE 1
LAND DISPOSAL RESTRICTIONS REGULATIONS1
Date
May 28, 1986
November 7, 1986
June 4, 1987
July 8, 1987
July 26, 1988
August 16, 1988
February 27, 1989
May 2, 1989
June 14, 1989
June 23, 1989
September 6, 1989
June 1, 1990
June 13, 1990
January 31, 1991
Federal Register2
51 FR 19305
51 FR 40636
52 FR 21014
52 FR 25787
53 FR 28118
53 FR 30908
54 FR 18266
54 FR 18837
54 FR 25422
54 FR 26647
54 FR 36970
55 FR 22683
55 FR 23935
56 FR 3876
Contents
Provides implementation schedule
Solvents and dioxins rule
Corrections to November 7, 1986 rule
"California List Wastes" (halogenated wastes,
certain metal-bearing wastes, polychlorinated
biphenyls [PCBs], and cyanide and corrosive
wastes)
Underground Injection Control (UIC): Solvents
and Dioxins
UIC: California List and some "First Third"
wastes (specific F, K, P, and U hazardous waste
codes)3
Amendment to schedule for multi-source leachate
Amendments to "First Third" rule
UIC: "Second Third" wastes (see §148.15)
"Second Third" wastes (see §268.11)
Corrections to August 17, 1988, and May 2, 1989,
"First Third" rules
"Third Third" wastes and characteristic wastes
(D001-D017)(see§268.12)
Corrections to September 6, 1989, rule
"Third Third" and characteristic wastes technical
correction notice
1 LDR regulations promulgated as of January 1991 are summarized in this document.
2 Federal Register (FR) citations (e.g., 51 FR 19305) are read Volume 51, Federal Register,
page number 19305.
*" Hazardous waste code will be used throughout this document to reference hazardous waste
numbers identified in 40 CFR §261.20-§261.24 and §261.33.
4 Notations such as §268.10, appearing in this document, refer to the section of Title 40 of
the Code of Federal Regulations (CFR) in which information pertaining to the specific
subject matter can be found.
5/93
23
-------
DISPOSAL OPTIONS
GLOSSARY OF TERMS
California List: Effective July 8, 1987, this rulemaking prohibited disposal (except by deep well
injection) of California List wastes. California List wastes are liquid and nonliquid hazardous wastes
containing HOCs above 1,000 ppm, liquid hazardous wastes containing PCBs above 50 ppm, certain
toxic metals above specified statutory concentrations, or corrosive liquid wastes that have a pH level
below 2. This list is based on regulations developed by the California Department of Health
Services.
Certification: A written statement of professional opinion and intent signed by an authorized
representative that acknowledges an owner or operator's compliance with applicable land disposal
restriction requirements. Certifications are required for treatment surface impoundment exemption
requests, applications for case-by-case extensions to an effective date, no-migration petitions, and
waste analysis and recordkeeping provisions applicable to any person who generates, treats, stores,
or disposes of hazardous wastes. The information referenced by the certification must be true,
accurate, and complete. There are significant penalties for submitting false information, including
fines and imprisonment.
Extraction Procedure Toxicity Test: The Extraction Procedure Toxicity Test (EP Tox Test) is used
to determine the toxicity characteristic of a waste. It is now being replaced by the TCLP.
Facility: A facility is defined as all contiguous land and structures (or other appurtenances) and
improvements on the land used for treating, storing, or disposing of hazardous waste. A facility may
consist of several treatment, storage, or disposal operational units (e.g., one or more landfills,
surface impoundments, or combinations of them).
First Third Rule: Effective August 8, 1988, this rule prohibited the land disposal of 62 wastes and
set restrictions on 121 others. It regulates some of the F-coded wastes such as bath solutions from
electroplating processes, some of the K-coded wastes such as acetonitrile production wastes, and
some of the P- and U-coded wastes that are discarded commercial chemical products such as
formaldehyde.
Hazardous and Solid Waste Amendments (HSWA): Amendment to RCRA in 1984. It minimizes
nation's reliance on land disposal of hazardous waste by, among other things, requiring EPA to
evaluate all listed and characteristic hazardous wastes according to a strict schedule to determine
which wastes should be restricted from land disposal.
Hazardous Waste: Waste that because of its quantity, concentration, or physical, chemical, or
infectious characteristics may cause, or significantly contribute to, an increase in mortality or an
increase in serious irreversible or incapacitating reversible illness, or pose a substantial present or
potential hazard to human health or the environment when improperly treated, stored, transported,
disposed of, or otherwise managed.
Hazardous Waste Code: The number assigned by EPA to each hazardous waste listed in 40 CFR
Part 162, Subpart D, and to each characteristic waste identified in 40 CFR Part 261, Subpart C.
5/93 24
-------
DISPOSAL OPTIONS
Lab Pack Wastes: A lab pack waste is an overpack container, usually a steel or fiber drum,
containing small quantities of chemicals of the same hazardous class.
Land Disposal Restrictions: Prohibits the land disposal of hazardous wastes into or on the land
unless EPA finds that it will not endanger human health and the environment. EPA must develop
levels or methods of treatment that substantially diminish the toxicity of the waste or the likelihood
that hazardous constituents will migrate from the waste that must be met before the waste is land
disposed. Strict statutory deadlines were imposed on EPA to regulate the land disposal of specific
hazardous wastes, concentrating first on the most harmful. EPA has met all of the Congressionally
mandated dates.
Notification: When restricted wastes are being shipped offsite for treatment, storage, and disposal
or are managed onsite, EPA has established a tracking system that requires that notifications and
certifications be sent to the receiving facility or, if applicable, to EPA or the appropriate EPA
representative. These requirements are outlined in 40 CFR §268.7.
Prohibition Levels: Treatment standards that when exceeded trigger statutory land disposal
prohibitions on certain wastes. These levels were established by the California List rule that
Congress incorporated into the 1984 amendments to RCRA.
Resource Conservation and Recovery Act (RCRA): The Resource Conservation and Recovery Act
of 1976 regulates hazardous waste generation, storage, transportation, treatment, and disposal. This
act was amended on November 8, 1984. The 1984 amendments (HSWA) significantly expanded the
scope and requirements of RCRA.
Second Third Rule: Effective June 8, 1989, this rule established treatment standards for 67
additional wastes and for the F-coded wastes not addressed in the first third rulemaking. Besides
specifying BDAT treatment standards, this rule expressed treatment standards as concentrations
measured in the treatment residues or required specific treatment methods (such as incineration) for
some wastes.
Solvents and Dioxins Rule: Effective November 7, 1986, this rule prohibited further land disposal
(except by deep well injection) of spent solvent wastes with EPA hazardous waste codes F001-F005
and dioxin wastes with hazardous waste codes F020-F023 and F026-F028. The rule also requires
that these wastes be treated prior to land disposal.
Subtitle C Facility: Solid waste regulated under Subtitle C of RCRA are hazardous and are directed
to Subtitle C disposal facilities. These facilities fall into three general categories: landfills, surface
impoundments, and land treatment facilities.
Subtitle D Facility: Solid waste regulated under Subtitle D of RCRA are primarily nonhazardous
and are directed to Subtitle D disposal facilities. These facilities fall into four general categories:
landfills, surface impoundments, land application facilities, and waste piles.
5/93 25
-------
DISPOSAL OPTIONS
Third Third Rule: Effective May 8, 1990, this fifth and final rulemaking pursuant to the
Congressionally mandated dates set treatment standards and imposed restrictions on 344 listed wastes
and all characteristic wastes. Two-thirds of the listed wastes have treatment standards expressed as
concentrations in the treated wastes, whereas the remaining wastes have treatment standards
expressed as specific technologies.
Tolling Agreement: A tolling agreement is a contract between a small quantity generator and a
recycling facility that arranges for collection and reclamation of a specified waste and for redelivery
of regenerated material at a specified frequency.
Toxicity Characteristic Leaching Procedure (TCLP): Promulgated in the November 7, 1986,
solvents and dioxins rule, this testing procedure was specifically initiated for evaluation of solvent-
and dioxin-containing wastes. EPA requires that when a waste extract is tested, the TCLP is used
to determine whether a waste requires treatment. Additionally, the TCLP is used to determine
whether a waste is hazardous and serves as a monitoring technique to determine whether a treated
waste meets the applicable waste extract treatment standard.
5/93 26
-------
Section 14
-------
ALTERNATIVE TREATMENTS
STUDENT PERFORMANCE OBJECTIVES:
At the conclusion of this section, participants will be able to:
• Briefly describe the reverse osmosis process
• Briefly describe the ultraviolet oxidation process
• Briefly describe the thermal desorption process
• Briefly describe the dehalogenation process
• Briefly describe the in situ vitrification process.
5/93
-------
NOTES
ALTERNATIVE TREATMENTS
• Reverse osmosis
• Ultraviolet oxidation
• Thermal desorption
• Dehalogenation
• Vitrification
REVERSE OSMOSIS
ADVANTAGES
• Selective ion removal
• Large volumes of liquid waste can be
treated
• Volume of waste for final disposal is low
• Ion recovery is possible
REVERSE OSMOSIS
DISADVANTAGES
Non-destructive, waste disposal required
pH and temperature range limited
Chlorine intolerance
5/93
Alternative Treatments
page 1
-------
NOTES
Osmosis
Osmotic
Pressure
Semipermeable
Membrane
Reverse Osmosis
SIMPLIFIED REVERSE OSMOSIS UNIT
Concentrated
Waste Water
Alternative Treatments
page 2
5/93
-------
NOTES
REVERSE OSMOSIS UNIT
Contaminated
Water
Treated
Water
Semipermeable
Membrane
Concentrated
Waste Water
REVERSE OSMOSIS SYSTEM
Storage
Tank
NaOH
V
Clarifier
^^^x-"
REVERSE OSMOSIS
COST
FLOW RATE
(gpm )
25
50
100
CAP. COST
($)
69,000
126.000
235,000
O & M COST
( $/yr )
30,000
41 ,000
76,000
5/93
Alternative Treatments
page 3
-------
NOTES
UV RADIATION/OXIDATION
Transformation of O.or H2 O2 to highly
reactive (OH) radicals
Initial attack of the target organics by UV
light
Applicable to waste streams
EFFECTS
Control
UV
UV / H2O2
Og/HjO,,
UV/03
UV / O3 / H2O2
Concentration
OF UV - 03
CH3CI2
100
42
17
21
16
7.6
- mg/l
-Hp2
CH3OH
75
75
75
-
31
1.2
UV OXIDATION SYSTEM
03
v^3
UV
Lamps -.
*pY —
&
0
-~~-,
o
o
0
O
•^
0
0
o
0
C
k
0
o
0
o
o
0
>
O
0
O
0
O
a
o
0
0
j
O
)
0
O
0
Q
0
0
o<
o
o
0
0
0
o
i
0
9
0
o
C
o
0
o
0°
o
9
0
O
o
o
O
o
0
oo o 0- o~ OO o°
Alternative Treatments
page 4
5/93
-------
NOTES
TREATMENT COSTS
Ozone @ 0.06/Kwh 0.119
H202@0.75/lb 0.118
UV including power and 0.133
annual lamp replacement
0 & M cost 0.440
Capital amortization 0.290
Total treatment costs $0.75/1000 gal
Flow rate: 210 gpm
Influent cone.: 5500 ug/l TCE
Effluent cone.: 1 ug/l TCE
LOW TEMPERATURE DESORPTION
ADVANTAGES
• Removes high percent of volatile organics
• Less expensive than incineration
• Contaminated soil returned to location
• Able to process 120-180 tons/day
• Will process volatile organics, semi-volatiles,
PCBs, and volatile metals (Hg and Pb)
LOW TEMPERATURE DESORPTION
DISADVANTAGES
• Not a destruction technology
• Process only works if the soil contains < 10% total
organics
• Technology only applicable to soil within the pH range
of 5-11
• Additional costs are incurred for carbon regeneration
and/or carbon disposal
• Process cannot be used on soils with high moisture
- contents
5/53
Alternative Treatments
page 5
-------
NOTES
Chemical Waste Management, Inc.
X* TRAX: Process Flow
Diagram
DEHALOGENATION
ADVANTAGES
Toxicity reduction of target compound
Mobility of treatment unit
Short residence time
Cost effective
DEHALOGENATION
DISADVANTAGES
• Limited to halogenated compounds
• Residuals
• Formation of explosive gases
Methyl sulfide
Chloroacetylene
• Severe corrosion problems
Alternative Treatments
page 6
5/93
-------
NOTES
Dehalogenation Flow Diagram
Nitrogen
-To *mo«ph.r.
Furttnt
> TrHtmen!
olOfl-SIU
Containing PCBl
or CJoiIni
VITRIFICATION
DESIGN SPECIFICATIONS
• Maximum and minimum area treated
• Fluxing material added
• Full-scale operation
In situ vitrification processes 4 to 6
tons/hour
0.3 to 0.5 kwh/pound of soil
Dual phase system requires 1.9
Mw/phase
VITRIFICATION
ADVANTAGES
Waste is fixed in a solid glass
monolith
Obsidian
Limited mobility of contaminants
5/93
Alternative Treatments
page 7
-------
NOTES
VITRIFICATION
DISADVANTAGES
• Not a destruction technology
• Possibility of leaching
• Limited number of vendors
• High energy consumption
• Backfill required
IN SITU VITRIFICATION
APPLICATION & EVALUATION
• Geosafe Corporation
• Inorganics and organics
• Soil matrix
• Cost data
$250-350 per ton
Alternative Treatments
page 8
5/93
-------
ALTERNATIVE TREATMENTS
THE QUEST FOR ALTERNATIVE TECHNOLOGIES
When Superfund was launched, land disposal was the most common method of handling hazardous
waste. Land disposal entailed immobilizing hazardous waste in a specially prepared pit, landfill, or
surface impoundment. Though cost-effective in the short run, it often led, through leaks and other
defects, to extremely expensive long-term environmental problems.
By the time the Resource Conservation and Recovery Act was reauthorized in 1984, opinion had
shifted dramatically in the direction of more permanent methods of handling hazardous waste. The
Superfund Amendments and Reauthorization Act of 1986 (SARA) continues the pendulum swing in
that direction.
SARA requires EPA, to the maximum extent practicable, to select remedial actions that create
permanent solutions and, in doing so, to make use of alternative or resource recovery technologies.
The least preferred remedial method is to transport untreated Superfund wastes to landfills.
Even before the passage of SARA, Superfund was making use of alternatives to land disposal.
Thermal destruction technology has been used in approximately 50 percent of all Superfund removal
actions. It is currently planned for use in approximately 40 percent of all Superfund remedial
actions. Various forms of chemical and physical treatment are included in current plans for
approximately 70 percent of remedial actions.
The leading technologies under consideration as alternatives to land disposal can be categorized
according to whether they destroy, immobilize, or separate the waste.
Waste Destruction Technology
"Destroying" hazardous waste means getting rid of most of it. Some harmful residues may
still be left behind, however, and these must be properly disposed of.
Thermal Treatment
The most common type of thermal treatment heats waste over a flame-powered incinerator.
Currently, if waste at a Superfund site is to be burned, it is usually removed from the site
and taken to the incinerator. In the future, EPA will make greater use of mobile
incinerators, which can be moved from one site to another as needed.
Various types of flame-free thermal treatments are now being developed to destroy hazardous
waste, including fluidized bed treatment, infrared treatment, plasma arc, and pyrolysis.
5/93
-------
ALTERNATIVE TREATMENTS
Neutralization
Certain types of hazardous waste can be "neutralized." For example, an acid can be added
to an excessively alkaline waste, or a base can be added to an overly acidic waste.
Waste Immobilization Technology
Immobilizing a waste puts it into a solid form that is easier to handle and less likely to enter
the surrounding environment. It is useful for dealing with wastes, such as heavy metals, that
cannot be destroyed. Once a waste has been immobilized, the material resulting from the
immobilization process must be properly disposed of.
Fixation and Solidification
Two popular methods of immobilizing waste are fixation and solidification. Engineers and
scientists mix materials such as fly ash or cement into hazardous waste. This either "fixes"
hazardous particles, in the sense of immobilizing them or making them chemically inert, or
"solidifies" them into a solid mass. Solidified waste is sometimes made into solid blocks that
can be stored more easily than a liquid.
Waste Separation Technology
Waste separation entails either separating one hazardous waste from another, or separating
hazardous waste from a nonhazardous material that it has contaminated. Sometimes this
separation is achieved by changing the waste from one form (solid, liquid, gas) to another.
Regardless of the way it is achieved, separation results in end products that can be adaptable
to recycling.
Air Stripping and Steam Stripping
Air stripping is sometimes used to remove volatile chemicals from water. Volatile chemicals,
which have a tendency to vaporize easily, can be forced out of liquid when air passes through
the liquid. Steam stripping works on the same general principle, except that it uses heated
air to raise the temperature of the liquid and force out volatile chemicals ordinary air would
not.
It should be noted that the mixture of air and chemicals that results from air and steam
stripping is still hazardous and must be further treated before release.
An interesting variation on this technology is now being used at the Verona Well Field site
in Michigan to remove volatile organic chemicals from the soil above an aquifer. Another
promising variant is landfill gas extraction, in which vacuum wells are used to remove gases
from soil.
5/93 10
-------
ALTERNATIVE TREATMENTS
Carbon Adsorption
Carbon adsorption tanks contain particles of carbon that have been specially activated to treat
hazardous chemicals in gaseous and liquid hazardous waste. The carbon chemically
combines with the waste or catches hazardous particles just as a fine wire mesh catches
grains of sand. Contaminated carbon must then be disposed of or cleaned and reused.
Precipitation
Precipitation involves adding special materials to a liquid waste. These bind to hazardous
chemicals and cause them to precipitate out of the liquid and form large particles called
"floe." Floe that settles can be separated as sludge; floe that remains suspended can be
filtered.
Soil Washing and Flushing
Soil containing easily dissolved chemicals can sometimes be cleaned by soil washing.
Cleaning liquid, added at the top of a tank of contaminated soil, picks up waste as it passes
through the soil. The contaminant-laden cleaning liquid must be further treated or properly
disposed of.
Soil flushing works on the same principle, except that it occurs in the ground rather than in
a tank. Soil is purified when cleaning liquid is passed through it; each time the liquid passes
through, it is collected by pipes or wells located at the base of the contaminated area.
Removing Obstacles to Innovation
While alternative technologies may be currently available, there are often serious
impediments to their use at Superfund sites. These include certain factors that EPA cannot
control, such as economic and marketplace uncertainties. One major uncertainty is the
degree to which the public will accept a particular means of handling hazardous waste. This
has been a special problem in the case of incineration.
There are other steps EPA can take to create a climate more receptive to alternative
technologies. EPA is moving ahead with them.
For example, EPA is setting up a quicker and more flexible method for selecting contractors
to clean up Superfund sites and to determine how Superfund wastes may be treated. EPA's
Office of Solid Waste is also working to streamline the Superfund Permitting process to give
high priority to issuing permits for alternative treatment technologies.
A new provision of SARA also fosters the use of alternative technologies by giving EPA the
authority, under certain circumstances, to assume liability for contractor efforts to test or
demonstrate alternative technologies.
5/93 11
-------
ALTERNATIVE TREATMENTS
In addition, a Superfund Innovative Technology Evaluation (SITE) program has been
established to demonstrate new and innovative technologies. Starting in the summer of 1987,
such technologies will be tested on real wastes in full-scale.situations at Superfund sites.
The results of these tests will generate vital cost and performance data, making it easier for
new technologies to compete in the real world. EPA has also developed a program to
communicate SITE data to appropriate offices within Superfund.
What Lies Ahead
Congress, EPA, and the U.S. public are seeking reliable, long-term solutions to the problem
of managing Superfund sites. Land disposal is no longer a preferred remedy, but it will take
some time for alternative technologies to develop sufficient capacity to fill the gap.
During the years ahead, alternative technologies will be substituted for landfilling at an
increasing number of Superfund sites. EPA is doing everything possible to hasten the day
when enough safe and reliable remedies exist to ensure that Superfund cleanups are
permanent.
Reverse Osmosis
General Description
Osmosis is the spontaneous flow of solvent (e.g., water) from a dilute solution
through a semipermeable membrane (impurities or solute permeates at a much slower
rate) to a more concentrated solution. Reverse osmosis is the application of sufficient
pressure to the concentrated solution to overcome the osmotic pressure and force the
net flow of water through the membrane toward the dilute phase. This allows the
concentration of solute (impurities) to be built up in a circulating system on one side
of the membrane while relatively pure water is transported through the membrane.
Ions and small molecules in true solution can be separated from water by this
technique.
The basic components of a reverse osmosis unit are the membrane, a membrane
support structure, a containing vessel, and a high-pressure pump. The membrane and
membrane support structure are the most critical elements. FIGURE 1 illustrates the
principle of reverse osmosis.
Applications/Limitations
Reverse osmosis is used to reduce the concentrations of dissolved solids, both organic
and inorganic. In treatment of hazardous waste contaminated streams, use of reverse
osmosis would be primarily limited to polishing low flow streams containing highly
toxic contaminants. In general, good removal can be expected for high molecular
weight organics and charged anions and cations. Multivalent ions are treated more
effectively than are univalent ions. Recent advances in membrane technology have
5/93 12
-------
ALTERNATIVE TREATMENTS
made it possible to remove such low molecular weight organics as alcohols, ketones,
amines, and aldehydes (Gooding, 1985). TABLE 1 shows removal results obtained
during testing of a mobile reverse osmosis unit using two favorable membrane
materials (Whittaker, 1984).
PRESSURE VESSEL
FEED
HIGH-PRESSURE
PUMP
CONCENTRATED
SOLUTION
DILUTE
SOLUTION
PERMEATE
REGULATING
VALVE
SEMIPERMEABLE
MEMBRANE
CONCENTRATE
FIGURE 1
REVERSE OSMOSIS
5/93
13
-------
ALTERNATIVE TREATMENTS
TABLE 1
RESULTS OF PILOT-SCALE TESTING OF A REVERSE OSMOSIS UNIT
Chemical
Dichloromethane
Acetone
1,1-Dichloroethene
Tetrahydrofuran
Diethyl ether
Chloroform
1 ,2-Dichloroethane
1 , 1 , 1-Trichloroethane
Trichloroethene
Benzene
Bromoform
Hexane
Feed
Concentration
(ppb)
406
110
34
17,890
210
270'
99
659
24'
539
12'
10'
Percent
Concentration
in
Concentrate
203
355
795
467
439
567
415
651
346
491
633
704
Percent removed in permeate
Polyether-
polysulphone
membrane
58
84
99
98
97
98
92
99.8
99
99
99.1
99.8
Polyester/
amide
polysulphone
membrane
52
76
95
89
89
92
85
97
99
99
98
97
1 No standard available; concentration estimated.
Source: Whittaker, 1984
Reverse osmosis units are subject to chemical attack, fouling, and plugging.
Pretreatment requirements can be extensive. Wastewater must be pretreated to
remove oxidizing materials such as iron and manganese salts, to filter out
particulates, adjust pH to a range of 4.0-7.5, and to remove oil, grease, and other
film forms (DeRenzo, 1978). The growth of slimy biomass on the membrane
surface, or the presence of organic macromolecules, may also foul the membrane.
This organic fouling can be minimized by prechlorination, addition of biocides,
and/or pretreatment with activated carbon (Ghassemi, Yu, and Quinlivan, 1981).
Design Considerations
The most critical design consideration applicable to reverse osmosis technology is the
design of the semipermeable membrane. In addition to allowing the achievement of
the required degree of separation at an economic flux level under ideal conditions,
the membrane must be incorporated into an operating system that satisfies the
following practical requirements (Conway and Ross, 1980):
5/93
14
-------
ALTERNATIVE TREATMENTS
• Minimum concentration polarization (i.e., ratio of impurity concentration at
the membrane surface to that in the bulk stream)
• High packing density (i.e., membrane surface area per unit volume of the
pressure module)
• Ability to handle any paniculate impurities (by proliferation if necessary)
• Adequate support for the membrane and other physical features such as
effectiveness of seals, ease of membrane replacement, and ease of cleaning.
Membranes are usually fabricated in flat sheets or tubular forms and are assembled
into modules. The most common materials used are cellulose acetate and other
polymers such as polyamides and polyether-polysulphone. There are three basic
module designs: tubular, hollow fiber, and spiral wound. These are illustrated in
FIGURES 2a, 2b, and 2c. Each type of membrane module has its own advantages
and limitations. The tubular module provides the largest flow channel and allows for
turbulent fluid flow regime; thus, it is least susceptible to plugging by suspended
solids and has the highest flux. However, because of its small area to volume ratio,
the total product recovered per module is small. The cost of a tubular module is
approximately 5 times that for the other modules for an equivalent rate of water
recovery, and the total space requirements is about 3-5 times that for the spiral
wound system (Ghassemi, Yu and Quinlivan, 1981).
A hollow fiber membrane is constructed of polyamide polymers and cellulose
triacetate by Dupont and Dow, respectively. The polyamide membrane permits a
wider operating pH range than cellulose acetate, which is commonly used for the
construction of spiral wound and tubular membranes. The flow channel and the flux
are about an order of magnitude lower than the other configurations. This small flux,
however, is compensated for by the large surface area to volume ratio, with the total
product water per module being close to that obtainable with spiral wound modules.
However, because of the small size of the channels (about 0.004 in.) and the laminar
fluid flow regime within the channels, this module is susceptible to plugging and may
require extensive pretreatment to protect the membrane (Ghassemi, Yu, and
Quinlivan, 1981).
5/93 15
-------
ALTERNATIVE TREATMENTS
CASING
\
S3>-
WATER
PLOW
MEMBRANE
FIGURE 2a
TUBULAR MEMBRANE
ROLL TO ,
ASSEMBLE ,-',
FEED SIDE
SPACER
FEED FLOW
V
PERMEATE FLOW
(AFTER PASSAGE
THROUGH MEMBRANE)
PERMEATE OUT
PERMEATE SIDE BACKING
MATERIAL WITH MEMBRANE ON
EACH SIDE AND GLUED ABOUND
EDGES AMD TO CENTER TUBE
FIGURE 2b
HOLLOW FIBER MODULE
5/93
16
-------
ALTERNATIVE TREATMENTS
CONCtXTKATE
OUTLET
FLOW
OPEN END
OF FIBERS
EPOXY
TUBE SHEET
POROUS
BACK-UP DISC
,SNAP KING
PERMEATE
END PLATE FIBER
SHELL
POROUS FEED V / iTC
DISTRIBUTOR "0" RING END PVATE
TUBE SEAL
FIGURE 2c
SPIRAL WOUND MODULE
Source: Ghassemi, Yu, and Quinlivan, 1984
The reverse osmosis unit being tested by Environment Canada can handle flow up to
11,000 gpd and costs approximately $60,000. Membranes vary considerably in cost.
The Toray and DSI membranes discussed in TABLE 1 for example, cost $360 and
$915, respectively (Whittaker et. al., 1985).
The spiral wound module consists of an envelope of flat sheet membranes rolled
around a permeate collector tube. This configuration provides for a higher flux and
greater resistance to fouling than the hollow fiber modules. It is also less expensive
and occupies less space than a tubular module (Ghassemi, Yu, and Quinlivan, 1981).
Technology Selection/Evaluation
Reverse osmosis is an effective treatment technology for removal of dissolved solids
presuming appropriate pretreatment has been performed for suspended solids
removal, pH adjustments, and removal of oxidizers, oil, and grease. Because the
process is so susceptible to fouling and plugging, on-line monitors may be required
to monitor pH, suspended solids, and other parameters on a continuous basis.
Reverse osmosis has not been widely used for treatment of hazardous wastes. A flow
diagram FIGURE 3 for a reverse osmosis unit at the PAS site in Oswego, NY is
shown.
5/93
17
-------
In-ground storage
tank
200,0001
Static mixer
02. micron
cartridge
filters
5 micron
cartridge filters
RO feed tank
Cap. 2,000 1
Reaction tank
Cap. 8001
Sludge: to disposal
RO system
02 micron
cartridge
filters
PC
2
>
H
FIGURES
PRETREATMENT SYSTEM UTILIZED FOR
THE PHASE II ENGINEERING STUDIES AT THE PAS SITE IN OSWEGO, NY
-------
ALTERNATIVE TREATMENTS
Reverse osmosis will not reliably treat wastes with a high organic content, because
the membrane may dissolve in the waste. Lower levels of organic compounds may
also be detrimental to the unit's reliability, because biological growth may form on
a membrane that is fed an influent containing biodegradable organics.
The fact that reverse osmosis units can be operated in series or in parallel provides
some flexibility in dealing with increased flow rates or concentration of dissolved
species.
Memtek Corporation of Ontario, Canada has developed a mobile reverse osmosis unit
for Environmental Canada. The unit, which is capable of handling low flows of
about 10 gpm, is currently being tested for various types of spills (Whittaker, 1984).
The volume of the reject generated by osmosis is about 10-25 percent of the feed
volume. Provisions must be made to treat this potentially hazardous waste.
Costs
Costs for various sizes of reverse osmosis units are presented in TABLE 2. The
construction costs include housing, tanks, piping, membranes, flow meters, cartridge
filters, acid and polyphosphate feed equipment, and cleanup equipment. These costs
are based on influent total dissolved solids concentrations of less than 10,000 ppm.
The operation and maintenance costs include electricity for the high-pressure feed
pumps (450 psi operating pressure), building utilities, routine periodic repair, routine
cleaning, and membrane replacement every 3 years. Operation and maintenance
costs do not include costs for pretreatment chemicals because of the extreme usage
rate variability between plants.
TABLE 2
REVERSE OSMOSIS COST
Flow Rate (gpm)
25
50
100
Cap. Cost ($)
69,000
126,000
235,000
O&M Cost ($/yr)
30,000
41,000
76,000
5/93
19
-------
ALTERNATIVE TREATMENTS
Freeze Crystallization
Freeze crystallization is the general separation process used to remove pure components from
solutions by crystallizing the materials to be removed. This process has been used for
applications as diverse as organic chemical refining and fruit juice concentration. It is
especially suited for treating hazardous wastes. The process can be used in site remediation
activities, including treating contaminated soils, where it can be used to recover valuable by-
products from RCRA and other industrial wastestreams. The basis for this process's
usefulness in mixed (hazardous and radioactive) wastes is also discussed.
Freeze Technologies Corporation has built a mobile, site remediation prototype of a
commercial plant to demonstrate the field remediation aspects of this technology. The
capacity of the unit is nominally 10 gpm of ice production from a leachate or groundwater,
at 90-percent water recovery. It is contained in two modules that are transported on standard
low-boy trailers and requires less than 1 week to set up.
Freeze crystallization has several advantages for remediation and waste recovery applications.
First, it is a very efficient volume reduction process, producing a concentrate that has no
additional chemicals added to it. If disposal in a hazardous waste landfill or incinerator
destruction is required, these costs will be substantially reduced. When a large fraction of
the solvent (usually water) is removed from a waste, the remaining impurities often begin to
crystallize as well; they are often sufficiently pure to have by-product value for resale.
Processing costs with freezing are generally low, ranging from $.03 to $.15 for 40 and 5
gpm plants, respectively.
Freeze Process Description
The basic operation involved in freeze crystallization is the production of crystals by
removing heat from a solution. Crystals produced in this manner invariably have very high
purities. Once small, uniform crystals have been produced, they must be washed to remove
adhering brine. The brine is recycled to the crystallizer, so that as much solvent as desired
can be recovered. The pure crystals are usually melted in a heat-pump cycle, which further
improves the energy efficiency of the process.
When one or more of the solutes exceeds its solubility additional crystal forms are produced,
but they are formed separately from each other and from the solvent crystals. Because in
most waste applications the solvent is water, and ice is always less dense than the solution
and the solutes are usually more dense, it is easy to separate these crystals by gravity.
A freeze crystallization process is then composed of the following components, as illustrated
in the process flow diagram of FIGURE 4:
• A CRYSTALLIZER, where heat is removed to lower the temperature of the material
to the freezing temperature of the solution (usually crystallizing the solvent first)
5/93 20
-------
ALTERNATIVE TREATMENTS
MELT
HEAT
REJECTION
CONDENSER
U-'
HEAT
REJECTION
COMPRESSOR
txj >- CONCENTRATE
OUTLET
FIGURE 4
FREEZE PROCESS FLOW SCHEMATIC
A EUTECTIC SEPARATOR to segregate the crystals of solvent and solute into
different streams, so that each can be recovered in pure forms
CRYSTAL SEPARATOR/WASHERS that function to remove the crystals from the
mother liquor in which they are slurried, and to wash adhering brine to very low
levels so that the recovered crystals have high purity
5/93
21
-------
ALTERNATIVE TREATMENTS
• A HEAT-PUMP REFRIGERATION CYCLE to remove refrigerant vapor from the
crystallizer and compress it so that it will condense and give up its heat to melt the
purified crystals
• HEAT EXCHANGERS to recover heat from the cold effluent streams, improving the
heat efficiency of the process
• DECANTERS and STRIPPERS are required in some processes to remove volatile
materials and/or refrigerant from the effluent streams before discharge
• UTILITIES, CONTROLS, ELECTRICAL SWITCH GEAR, PUMPS and PIPING
to implement the freeze process in a continuous, closed system.
The design, operating characteristics, capabilities, and limitations are determined largely by
the type of crystallizer that is used, of which there are three basic choices:
1. INDIRECT CONTACT, using a scraped surface or similar heat exchanger that will
crystallize by removing heat through the heat transfer surface.
2. TRIPLE POINT crystallizers use the solvent as the refrigerant at its triple point
(where solid, liquid, and vapor phases are all in equilibrium). For instance, with
aqueous systems, the triple point occurs at less than 3 mm Hg absolute pressure at
30°F or below.
3. SECONDARY REFRIGERANT freezing uses an immiscible refrigerant that is
injected directly into the process fluid and evaporates at several hundred to several
thousand times the vapor pressure of the solvent.
The third option offers a number of advantages in treating hazardous wastes, resulting in a
less expensive process that is inherently capable of producing higher quality effluents and
effecting a greater reduction of the final volume.
10 gpm Remediation Prototype
The freeze crystallization process that has been accepted into EPA's SITE Program is a
secondary refrigerant process. A prototype commercial remediation plant has been designed
and built for that program. The capacity of the plant is a nominal 10 gpm of ice produced
from an aqueous wastestream with a freezing point of 20°F.
The plant contained all of the components described in a typical freeze crystallization process
above, including the crystallizer, eutectic separator, crystal separator/washer, heat
exchangers, heat pump (pen cycle screw compressor), decanters and strippers, and ancillary
utility related systems.
5/93 22
-------
ALTERNATIVE TREATMENTS
The plant was designed for ultimate transportability, using modular design concepts
developed by Applied Engineering Co., Orangeburg, South Carolina, the acknowledged
leader in this field. The plant was contained in two modules designed for transport on the
back of low-boy trailers. Each measures approximately 50 ft 1 in. by 13 ft by 11.5 ft. They
were picked off upon arrival at the site by a standard road crane, and one was placed on top
of the other. The 3 electrical and 30 flanged-piping interconnections take about a day to
complete.
The plant is totally self-contained except for electrical supply, containing instrument air,
cooling water, electrical distribution, and electrical heating components. It has a distributed
digital processor that is programmed to operate without attendance, using on-line quality
sensors to evaluate process efficiencies and discern any operating problems, recycling effluent
for reprocessing if warranted. Cost summary results show three different size units. The
greater the flow rate, the more economical the system will be to operate (TABLE 3).
TABLE 3
FREEZE CRYSTALLIZATION COST SUMMARY
Cost Component
Amortization, 5-year SLD
Labor
Electricity
Supplies, chemicals, etc.
Maintenance
TOTALS
Cost at Plant Size, $/Gal.
5 gpm
$.08
.04
.008
.010
.007
.145
10,gpm
$.05
.02
.0075
.0075
.005
.09
40 gpm
$ .015
.005
.006
.005
.004
.035
5/93
23
-------
ALTERNATIVE TREATMENTS
SITE Demonstration Program - Stringfellow NPL
The FTC Direct Contact Secondary Refrigerant Freeze Crystallization Process was accepted
by EPA's Office of Research & Development, SITE Program, into the third phase of their
program, when first proposed by Freeze Technologies. A program with the State of
California, Department of Health Services, Alternative Technologies Office, was already in
place, and the selection of the Stringfellow NPL site had been agreed to with the state.
The goals of the SITE program are, among other things, to demonstrate applicability of a
technology on as general a wastestream as can be found and to develop the best economic
and performance criteria that can be projected from test results. Freeze Technologies
proposed that testing could be performed with either a 0.5 gpm portable pilot plant or with
a 10 gpm prototype remediation plant, designed specifically for Superfund work. The groups
involved in the demonstration of this technology concurred unanimously that the larger plant
is a better vehicle for accomplishing the goals of the program.
The current schedule will have the equipment at the Stringfellow NPL site in late July and
installed and ready to operate in early August. The SITE tests and sampling program will
occur over a 2- to 3- week schedule in August, with a public visitors day on Sunday, August
16, 1989. Further testing for reliability and longer-term performance confirmation will
continue into September and the plant will be removed from the site by the end of
September, after appropriate decontamination.
This demonstration program is designed to have minimal impact on the host site, a condition
that is paramount in the planning at the EPA Regional level and with local communities. The
freeze equipment will be fit in as a "black-box" in the pipeline that carries wastes from the
NPL site to the onsite pretreatment plant. We will intercept the wastes between the collection
wells and the pretreatment plant, process the wastes, then recombine them for transfer to the
pretreatment plant. The residence time in the freeze crystallization plant, including storage
before and after the actual freeze processing equipment, will be 72 hours.
Because the freeze process operates in closed vessels, with recycling of refrigerants and
wastes at temperatures well below ambient, there are no emissions from the process. An
option exists at Stringfellow for treating the concentrated effluent for metals recovery, for
organic by-product extraction, or by solidifying the concentrate for subsequent landfilling.
The by-product recovery is an attractive option because it eliminates a large volume that is
now landfilled. TABLE 4 shows the analysis of the feed and melt.
5/93 24
-------
ALTERNATIVE TREATMENTS
TABLE 4
STRINGFELLOW LEACHATE ANALYSES
Component
pH
Conductivity, mS/cm
Dissolved Organic Carbon
p-CBSA
Volatile halocarbons
Volatile ketones
Na
Total heavy metals
Al
Cd
Cr(6+)
Cu
Fe
Mg
S04
NO3
Concentration, mg/1
Feed
3.5
39
1125
1670
9.7
14.
820
3385
1650
2.5
85
9
335
1160
16,200
335
320
Melt
6.5
0.02
<1
<1
< 0.010
< 0.010
<1
<5
<1
<0.010
<0.010
<0.010
<1
<1
<5
<1
<1
Waste Treatment with Bv-Product Reclamation
Remediation offers some opportunities for by-product recovery, but more frequently these
applications occur in on-going RCRA generation facilities. The following discussion covers
generic conditions that favor freeze crystallization treatment and how other unit processes can
be used with freezing to offer a complete remediation or by-product recovery process train.
In addition, a few recent applications that have been reviewed and tested using freeze
crystallization will also be discussed.
Generic Application Considerations
Freeze crystallization works by making pure crystals from water, or other components, in
a waste solution. The waste must be in liquid form, so contaminated soils are treated by first
washing the impurity out of the soil into a wash solvent (usually water). In the case of
5/93
25
-------
ALTERNATIVE TREATMENTS
aqueous-based wastes, the crystal that is produced is ice, and all impurities are excluded and
remain in the concentrated liquid portion. The process is effective in removing water from
these wastes, thereby reducing the volume that must be dealt with.
Because crystallization excludes all impurities from the ice, all impurities are equally
removed. The freeze process is capable of treating wastes with heavy metals, all types of
dissolved organics, and radioactive materials. All impurities are reduced in concentration
in the effluent bv a factor of about 10.000.
Freeze crystallization is not the answer for all applications. The information in FIGURE 5
indicates the conditions that favor its use over alternative treatment technologies. The chart
demonstrates that freezing becomes more economically and technically competitive as the
waste becomes more concentrated and more complex. For instance, wastes with heavy
metals require concentrations of 1,000-10,000 mg/1 to be economically recoverable with
freezing. Aqueous streams require organic concentrations of 3-7 wt-% before it is more
economical to treat with freeze crystallization than by conventional means. Yet, when the
waste contains both organics and heavy metals, freeze crystallation becomes more economical
than multiprocess treatment trains using conventional technologies at between 0.5 and 1.5 wt-
% total contaminants.
1
N
C
R
E
A
5
E
D
C
0
N
C
E
N
T
R
A
s,
N1
'
TYPE OF CONTAMINANT
VOLATILE HEAVY
ORGANICS ORGANICS
SALTS
STRIPPING
CARBON ADSORPTION
BIOLOGICAL & CHEMICAL
OXIDATION
R
HEAVY
METALS
ION EXCHANGE
ELECTRODIALYS1S
EVERSE OSMOSIS
EVAPORATION
FREEZE CRYSTALLIZATION
FIGURE 5
TECHNOLOGY COMPARISON CHART
5/93
26
-------
ALTERNATIVE TREATMENTS
UV Radiation. Ozone. Hydrogen Peroxide
This section provides an overview of the Ultrox technology and a description of the treatment
system equipment, support equipment, and utility requirements. Detailed descriptions of the
Ultrox treatment technology are present in the Demonstration Plan (PRC, 1989).
Process Description
The use of oxidants such as ozone, hydrogen peroxide, and ultraviolet (UV) radiation
to destroy organic contaminants present in groundwater is gaining considerable
attention, mainly because the oxidants destroy the contaminants instead of transferring
them to another phase. Alternative treatments, such as air stripping, granular
activated carbon (GAC) adsorption, and reverse osmosis, require additional treatment.
Ultrox International developed a technology that uses three oxidants: ozone,
hydrogen peroxide, and UV radiation. The Ultrox technology is best suited for
destroying dissolved organic contaminants, including chlorinated hydrocarbons and
aromatic compounds, in water with low suspended solids levels. This technology is
currently treating contaminated groundwater at facilities located in Kansas City,
Missouri; Nashua, New Hampshire; and Muskegon, Michigan. Groundwater at these
sites is contaminated with trichloroethylene, tetrachloroethylene, vinyl chloride,
pentachlorophenol, phenol, and various other organics. The design flow rates of
these facilities are in the range of 20 to 210 gpm.
Process Chemistry
Processes in which ozone is used in combination with hydrogen peroxide or UV
radiation may be categorized as catalytic processes. These processes accelerate ozone
decomposition, thereby increasing the hydroxyl radical (OH~) concentration and
promoting the oxidation rate of the compounds of interest. Specifically, hydrogen
peroxide, hydroxide ion, UV radiation, and some transition metal ions such as
ferrous iron (Fe2+) have been found to initiate ozone decomposition and accelerate
the oxidation of refractory organics via the free radical reaction pathway. Natural
water components such as carbonate ions, bicarbonate ions, cyanide ions, nitrite ions,
and several other species that consume oxidants act as free radical scavengers and
effectively consume hydroxyl radicals.
The ozone-hydrogen process is affected by the molar ratio of the oxidants used. For
example, the expected stoichiometry for hydroxyl radical formation from ozone and
hydrogen peroxide is two, as shown in the following equation:
H2O2 + 203 ** 2 OH" + 3 O2
5/93 27
-------
ALTERNATIVE TREATMENTS
In the treatment of water containing trichloroethylene and tetrachloroethylene, Aieta
et al. (1988) observed maximum removals at a molar ratio of 2 or a 2.86 weight ratio
of ozone to hydrogen peroxide, which agrees with the expected stoichiometry. The
removals were significantly less when the molar ratio was not 2. Although in this
case the expected stoichiometry for pure water agreed with the molar ratio at which
optimum removal was observed, several factors may influence the molar ratio (Aieta
et al., 1988). These factors are summarized below:
• Hydrogen peroxide can act as a free radical scavenger itself, thereby
decreasing the hydroxyl radical concentration if it is present in excess
• Ozone can directly react with hydroxyl radicals, consuming both ozone and
hydroxyl radicals
• Ozone and hydroxyl radicals may be consumed by other constituents, known
as scavengers, of the water to be treated.
In the ozone-UV process, the UV photolysis of ozone in water yields hydrogen
peroxide rather than two hydroxyl radicals. Thus, the ozone-UV process resembles
the ozone-hydrogen peroxide process, but offers the additional advantage that direct
photolysis and photosynthesized processes also decompose organic substrates.
The Ultrox process, therefore, can be viewed as a catalytic ozonation process and the
oxidation of contaminants is likely to occur either by direct reaction of the oxidants
added or by reaction of the hydroxyl radicals with the contaminants. The optimum
proportion of the oxidants for maximum removals cannot be predetermined; rather,
the proportion must be experimentally determined for each wastestream. The
following section identifies specific factors that influence the effectiveness of the
Ultrox technology in treating the groundwater at the LB&D site.
Factors Affecting the Ultrox Technology
The factors that affect the Ultrox technology can be grouped into three categories:
1. Performance evaluation parameters
2. Operating parameters
3. Miscellaneous parameters.
The performance evaluation parameters of the Ultrox technology at the LB&D site
under specified conditions were specific chemical constituents. These constituents are
volatile organic compounds (VOCs), semivolatile organics, polychlorinated biphenyls
(PCBs), and pesticides. The influent concentrations of these constituents can
significantly influence the treatment efficiency of the technology.
5/93 28
-------
ALTERNATIVE TREATMENTS
Operating parameters are those parameters that were manually varied during the
treatment process to achieve a desired degree of treatment efficiency. Such
parameters included hydraulic retention time, ozone dose, hydrogen peroxide dose,
UV radiation intensity, and influent pH level.
Because the Ultrox technology is an oxidation process and is intended for the
destruction of organic contaminants, any other species present in the contaminated
water that consume oxidants were viewed as an additional load for the system. These
species, called scavengers, include anions such as carbonates, bicarbonates, sulfides,
nitrites, bromides, and cyanides. Also, metals present in reduced states, such as
trivalent chromium (Cr3*), ferrous iron (Fe2"1"), and several others, are likely to be
oxidized. In addition, physical characteristics of the influent, such as temperature
and pH, also influence the Ultrox process.
Treatment System Equipment
The treatment system used to demonstrate the Ultrox process is shown in FIGURE
6. This system (Model PM-150) uses UV radiation, ozone, and hydrogen peroxide
to oxidize the modules designed for transport with either a flatbed truck or in an
enclosed trailer. The major components of the system include the following:
• UV radiation/oxidation reactor module
• Ozone generator module
• Hydrogen peroxide feed system
• Catalytic ozone decomposer unit.
5/93 29
-------
ALTERNATIVE TREATMENTS
nn-
I I U_ E«ii.~>t
tio..o>
FIGURE 6
ULTROX SYSTEM FLOW DIAGRAM
An isometric view of the Ultrox system is given in FIGURE 7. The UV
radiation/oxidation reactor used for this demonstration has a wet volume of 150
gallons and is 3 ft by 1.5 ft by 5.5 ft. The reactor is divided by 5 vertical baffles
into 6 chambers and contains 24 UV lamps (65 watts each) in quartz sheaths. These
lamps are installed vertically and are evenly distributed throughout the reactor (four
lamps per chamber). Each chamber also has one sparger that covers the width of the
reactor. These spargers provide a supply of uniformly diffused ozone gas from the
base of the reactor into the treated groundwater.
5/93
30
-------
W.TWOX
UV/OXJO»TX)M REACTOR
TH6ATEO
EfTVUEHT
TOOtSCMAflCE
All
FIGURE 7
ISOMETRIC VIEW OF ULTROX SYSTEM
-------
ALTERNATIVE TREATMENTS
The ozone generator requires compressed air as a source of oxygen for onsite
generation of ozone. The air compressor operates in association with an air dryer,
which removes moisture. In addition, a water cooler recirculates cooling water
supplied to the ozone generator.
The hydrogen peroxide feed system introduces a predetermined concentration of
hydrogen peroxide to the reactor via an influent feed line. Commercial-grade
hydrogen peroxide of known concentration (about 35 percent) was purchased from
a chemical supplier and diluted with distilled water to the appropriate concentration.
An in-line static mixer disperses the hydrogen peroxide from the feed tank into the
groundwater as groundwater is pumped through the influent feed line.
The catalytic ozone decomposer unit (Ultrox Model 3014 FF ozone decomposer)
catalytically decomposes ozone to oxygen using a nickel catalyst. The ozone
decomposer (Decompozon) unit can accommodate flows of up to 10 standard cubic
feet per minute. The unit is rated to decompose ozone concentrations ranging from
1 to 20,000 ppm (by weight) to less than 0.1 ppm.
During the demonstration operation, contaminated groundwater came in contact first
with hydrogen peroxide as it flowed through the influent line to the reactor. It then
came in contact with UV radiation and ozone while it flowed through the reactor at
a specified rate to achieve the desired hydraulic retention time. The hydrogen
peroxide dose was controlled by varying the ratio of the hydrogen peroxide feed flow
rate to the influent contaminated water flow rate. Similarly, the ozone dose was
controlled by varying the ration of the ozone gas flow rate to the contaminated water
flow rate and, also, the ozone feed gas concentration. The treatment system was
designed so that ozone present in the off-gas from the reactor could be destroyed
using a catalyst by the Decompozon unit. Treated groundwater effluent was pumped
from the reactor to a storage tank.
Treatment System Support Equipment
Typically, support equipment is needed depending on the site logistics, required
operating procedures, and equipment limitations. Submersible discharge pumps may
be needed to bring groundwater from the source to the Ultrox system. In addition,
a submersible pump is commonly needed to pump the effluent from a small capacity
container to a storage tank. As discussed previously, an air compressor is frequently
used to generate ozone from air. However, in some applications an alternative air
source is used, such as compressed air or oxygen cylinders.
For the demonstration, two collapsible bladder tanks were used to store site
groundwater in order to reduce VOC losses. The treated water was pumped from
an effluent collection tank to an effluent storage tank in all test runs. The combined
effluent from all the runs was stored in the storage tanks until the effluent was
analyzed and found to be acceptable for discharge into Coyote Creek, a nearby
watercourse.
5/93 32
-------
ALTERNATIVE TREATMENTS
Utility Requirements
Utilities required for the Ultrox system demonstration included water, electricity, and
telephone service.
• Water - Tap water was required for the Ultrox process and for equipment and
personnel decontamination. During operation, the Ultrox system required
less than 3.5 gpm of cooling water. A recirculating chiller enabled reuse of
cooling water. Water used for equipment and personnel decontamination was
provided using existing site pipelines.
• Electricity - Electricity was required to operate the Ultrox system, the office
trailer, and the laboratory equipment. The Ultrox system required 480-volt,
3-phase electrical service. Also, 110-volt, single-phase power was needed for
lighting the field trailer and operating the onsite laboratory equipment.
Oxygen Enhanced Incineration
Technology Description and Explanation of Developers Claim
The Pyretron Thermal Destruction System is designed for application to a rotary kiln
incinerator. It consists of two burners, one installed in the primary combustion
chamber (kiln) and one installed in the afterburner; valve trains for supplying these
burners with controllable flows of auxiliary fuel, oxygen, and air; a computerized
process control system; an oxygen supply system; and a kiln water injection system.
A schematic of the system is shown in FIGURE 8. The Pyretron burners use a
parallel combustion approach based on the independent introduction of two distinct
oxidizers to each burner, each of which has significant differences in oxygen content.
In most situations, as demonstrated in this test program, one of the two oxidizers will
be pure oxygen, whereas the second oxidizer will be air and/or oxygen-enriched air.
5/93 33
-------
VO
OJ
r
rf
i
Afterburner Pyretron burner
Transfer
duct
Ash
pit
Afterburner
r
r
Kiln Pyretron
burner
Measured
process
parameters
i
n
r*
o
9
-------
ALTERNATIVE TREATMENTS
The burner is designed to provide a pyrolytic combustion zone where fuel is mixed
with pure oxygen under substoichiometric conditions. This pyrolytic zone, which is
located inside the flame envelope, is used to provide high flame luminosity and
stability. A second combustion stage is established by secondary oxidizing gas,
typically air or oxygen-enriched air. The secondary oxidizing gas is directed toward
the pyrolytic flame core from the area surrounding the core inside a water-cooled
burner chamber. The resulting oxidation of the fuel stream from both inside and
outside directions results in rapid oxidation and expansion of the combustion products
before they leave the burner tunnel, thus providing a high-velocity, highly turbulent
flame that serves to enhance oxygen mass transfer inside the incineration chambers.
The system uses a programmable logic controller to effect process control. The
control system is based on a process control algorithm that is designed to maintain
both process temperature and excess oxygen levels. This control algorithm allows
preset responses to process deviations (discussed below) by changing the amount of
nitrogen-containing combustion air introduced into the incineration process. Nitrogen
occupies a major fraction of a conventional combustion chamber volume and likewise
represents a sink for a major fraction of the burner heat input. In the Pyretron
system, the amount of nitrogen can be controlled by varying the ratio of the two
oxygen sources (air and oxygen) delivered to the burners.
When the combustion system of a conventional kiln and afterburner uses only air to
supply combustion oxygen, the only process parameter that can be controlled to
maintain the desired operating temperatures is the auxiliary fuel heat input introduced
by the burners. When the Pyretron system is used, an additional process control
parameter exists, namely the percent of oxygen in the combustion air supplied to the
burners. With the Pyretron system it is possible to replace 50 percent of the amount
of combustion oxygen available for organic contaminant destruction without adding
additional diluent nitrogen. Combustion gas temperatures can be maintained with a
lower auxiliary fuel heat input because the combustion gas heat sink represented by
the additional nitrogen is removed. In addition, combustion gas residence time is
increased because the diluent nitrogen is removed from the combustion gas volume.
Dedicated carbon monoxide (CO) and oxygen analyzers are used in addition to stack
gas analyzers to supply the computerized control system information on the measured
levels of CO and excess oxygen in the exhaust gases from the primary combustion
chamber. When the levels of CO and/or excess oxygen deviate from a level deemed
appropriate for the given composition and feed volume of the waste, the system can
initiate a preprogrammed firing schedule in the primary and afterburner chambers to
bring the process back to the desired operating conditions through an automatic
increase in the oxygen feed rates, with or without a simultaneous reduction in
combustion air supply.
In a typical application, the control algorithm increases the flow rate of oxygen to
both the kiln and afterburner burners when one of three events occur:
5/93 35
-------
ALTERNATIVE TREATMENTS
• A batch waste change event with a predetermined and preset (in the
algorithm) subsequent time lapse
• Kiln exit CO levels exceed a predetermined and preset level
• Kiln exit 02 levels decrease below a predetermined and preset level.
A baseline oxygen flow rate to each burner is also preset, as in the increased level
to which oxygen flow is increased following one of the other above events. When
one of the three events occurs, oxygen flow rates are increased from the baseline
levels to the preset higher levels and held at these levels for preset period of time.
After this time period, oxygen flow rates are returned to baseline levels provided no
triggering condition still exists (e.g., sustained high CO or low
Burner air flow rates are typically controlled to maintain a preset ratio of air to
auxiliary fuel. Thus, air flow rates increase and decrease with corresponding changes
in auxiliary fuel feed rates. Fuel feed rates, in turn, are varied in response to
combustor (kiln, afterburner) temperature variations. The control system varies fuel
flow rates to maintain combustor temperatures at their set points. Preset changes in
air flow rates accompanying the oxygen flow rate changes can be incorporated over
and above the preset air/fuel ratio if desired. This additional air flow rate control is
optional:
ACI proposes that three major advantages will result from application of the system
to a rotary kiln incinerator:
• The Pyretron system will be capable of reducing the magnitude of transient
high levels of CO, unburned hydrocarbon, and soot ("puffs") that can occur
with repeated batch charging of a high heat content waste to a rotary kiln
• The Pyretron system will allow increased waste feed rate to the kiln while
still achieving the hazardous waste incinerator performance standards for
POHC destruction and removal efficiency (DRE) and paniculate emissions
• The Pyretron system is more economical than conventional incineration.
The basis for the first claim is as follows. Rotary kiln incinerators are unique in that
they are designed to allow at least a portion of the waste load to be introduced or
charged to the system in a batch, rather than continuous, mode. For organic, heating
value-containing wastes, a portion of the heat input to the system is correspondingly
introduced in a batch mode. Typically, waste containerized in cardboard, plastic, or
punctured steel drums is charged to the kiln at established intervals. Upon entry to
the kiln, the waste containers are heated until they rupture or burn. This then
exposes the waste contents to the hot kiln environment. Volatile organic material
then rapidly vaporizes and reacts with available oxygen in the combustion gas.
5/93 36
-------
ALTERNATIVE TREATMENTS
However, if the devolatilization of organic material is more rapid than the rate at
which combustion oxygen can be supplied to the kiln, incomplete combustion can
result. This can lead to a puff of incompletely destroyed organic material exiting the
kiln. In most instances, this puff will be destroyed in the system's afterburner. In
fact, afterburners are included in rotary kiln incinerator systems for this very reason.
However, if the puff is of sufficient magnitude, insufficient excess oxygen and/or
residence time may exist in the afterburner to allow its complete destruction.
In conventional incineration systems, the only way to ensure that sufficient oxygen
exists in the kiln to allow complete waste oxidation is to increase the air flow rate to
the kiln. This can be accomplished either by steadily firing the kiln burner at higher
excess air than needed to burn the burner fuel or by increasing the air flow rate in
anticipation of or in response to a puff. In either instance, an increased air flow rate
adds both increased oxygen for waste combustion and increased nitrogen. The
increased diluent nitrogen flow is detrimental to complete waste destruction for two
reasons. Its presence in the combustion gas volume decreases kiln combustion gas
residence time, and, because the nitrogen must be heated, it decreases combustion gas
temperature.
In contrast, the Pyretron system offers the capability to increase the amount of
oxygen in the combustion process in anticipation of or in response to a puff while not
adding diluent nitrogen. Thus, kiln temperature can be more easily maintained and
additional oxygen needed for waste puff destruction can be introduced with far less
an effect on combustion gas volume, hence combustion gas residence time, than
possible with air alone. This extra oxygen, without diluent nitrogen, is available for
waste puff oxidation. With this additional kiln condition control flexibility, the
magnitude of transient puffs should be reduced as compared to similar operating
conditions with conventional incineration.
The basis for the second claim, that the Pyretron System will allow increased waste
feed rate in a given kiln system, follows from the basis of the first claim. The
maximum feed rate of a high organic content waste in a conventional incinerator is
determined by the onset of transient puffs that survive the afterburner. When this
occurs, waste constituent destruction is less than complete and eventually falls below
the regulation mandated 99.99 percent hazardous constituent DRE.
The discussion supporting the first claim noted that because the additional oxygen to
support waste combustion would be supplied without diluent nitrogen in the Pyretron
system, incineration residence times would be greater for a given waste and auxiliary
fuel feed rate. Therefore, incineration destruction efficiency would be greater.
Thus, a feed rate that produced unacceptable transient puffs under conventional
incineration would not do so with the Pyretron system. Correspondingly, the onset
of unacceptable transient puffs under Pyretron operation would occur at a higher
waste feed rate. Thus, acceptable operation at higher waste feed rate (or throughput)
should be possible with the Pyretron system.
5/93 37
-------
ALTERNATIVE TREATMENTS
The Pyretron system uses oxygen for a portion of the waste oxidant (instead of air).
Therefore, a given set of incineration temperatures can be maintained with less
auxiliary fuel feed than is possible with conventional incineration. Less diluent
nitrogen is fed, thereby obviating the need to heat it to combustion temperature.
Thus auxiliary fuel use per unit of treated waste is less for the Pyretron system than
for conventional incineration.
In addition, if higher waste feed rates can be employed in a given combustor with the
Pyretron system, then the treatment time required per unit of waste is decreased.
This affords further operating cost savings as well as capital recovery cost savings
per unit of waste treated.
The test program discussed here was specifically designed to evaluate the first two
of the above claims and to establish needed data to evaluate the third.
Dehalogenation
Technology Description
The alkaline metal hydroxide/polyethylene glycol (APEG) dehalogenation technology
uses a glycolate reagent generated from an* alkaline metal hydroxide and a glycol to
remove halogens (e.g., chlorine, bromine, and fluorine) from halogenated aromatic
organic compounds in a batch reactor. KPEG (potassium hydroxide/polyethylene
glycol) is the most commonly used type of APEG reagent. Potassium hydroxide, or
sodium hydroxide/tetra-ethylene glycol (ATEG), is another variation of the reagent.
APEG processes involve heating and physical mixing of contaminated soils, sludges,
or liquids with the chemical reagents. During the reaction, water vapor and volatile
organics are removed and condensed. Carbon filters^re used to trap volatile organic
compounds that are not condensed in the vapor. The treated residue is rinsed to
remove reactor by-products and reagent and then dewatered before disposal. The
process results in treated soil and wash water.
Application
• Selected by EPA for cleanup at three Superfund sites: Wide Beach, New
York; Re-Solve, Massachusetts; and Sol Lynn, Texas. None of these
cleanups has been completed.
• Approved by EPA's Office of Toxic Substances to treat PCBs under the
Toxic Substances Control Act.
5/93 38
-------
ALTERNATIVE TREATMENTS
Technology Strengths
• Greater public acceptance than for incineration.
• Reduces the toxicity of halogenated organic compounds, particularly
dioxins and furans, PCBs, and certain chlorinated pesticides in soils,
sludges, sediments, and liquids.
• Has successfully treated contaminant concentrations of PCBs reported
as high as 45,000 ppm to less than 2 ppm.
• Uses standard reactor equipment to mix/heat soil and reagents.
• Energy requirements are moderate, and operation and maintenance
costs are relatively low.
Technology Limitations
• Most effective with aromatic halides when APEG and KPEG reagents
are used, although ATEG reportedly works with aliphatic halides.
The presence of other pollutants, such as metals and other organics,
can interfere with the process.
• Wastewater will be generated from the residual washing process.
Treatment may include chemical oxidation, biodegradation, carbon
adsorption, or precipitation.
• Engineering controls, such as a lined and bermed treatment area and
carbon filters on gas effluent stacks may be necessary to guard against
releases to the environment.
Waste Characteristics Affecting Performance
• Treatability studies are necessary to help determine the residence time
in the reactor. The treatment process is affected by the type of
contaminant; initial and desired final concentrations; pH; water
content; and humic and clay content of soils (TABLE 5).
• The ability to recover and recycle reagents is key to determining
process cost-effectiveness.
• Although individual batch units may have limited capacity, several
may be operated in parallel for a large-scale remediation.
5/93 39
-------
ALTERNATIVE TREATMENTS
TABLE 5
WASTE CHARACTERISTIC
Waste Type:
Technology:
Soils and Sludges
Glycolate Dechlorination
Characteristics
Impacting Process
Feasibility
Reason for Potential Impact
Data
Collection
Requirements
Elevated Concentrations of
chlorinated organics
Concentrations greater than
5% require excessive
volumes of reagent (low ppm
is optimum).
Analysis for priority
pollutants
Presence of:
• Aliphatic organics
• Inorganics
• Metals
Reagent effective only with
aromatic halides (PCBs),
dioxins, chlorophenols, and
chlorobenzenes.
Analysis for priority
pollutants
High moisture content
Water may require excessive
volumes of reagent.
Soil moisture content
LowpH(<2)
Process operates under highly
alkaline conditions.
pH testing
Presence of other alkaline
reactive
Aluminum and possible other
metals that react under highly
alkaline conditions may
increase amount of reagent
required by competing for the
KPEG. The reaction may
also produce hydrogen gas.
Metals analysis
High humic content in soil
Increases reaction time. Clay
and sandy soils as well as
high organic content soils can
be treated with increased
reaction time.
Organic content in soil
Source: Technology Screening Guide for Treatment of Soils and Sludges EPA/540/2-88/004
5/93
40
-------
ALTERNATIVE TREATMENTS
BASE-CATALYZED DECOMPOSITION (BCD)
BCD is another technology for removing chlorine molecules from contaminants such as PCBs,
dioxins, and pentachlorophenols. The EPA and the U.S. Navy are conducting extensive research
on this new technology. Like the KPEG process, BCD requires the addition of a reagent to the
contaminated soils and heating of the material for the reaction. But because the reagent is not a
glycol reagent, it is significantly less expensive than the KPEG reagent.
Laboratory research indicates that the BCD process is appropriate for PCBs, pentachlorophenol,
dioxins, and chlorinated pesticides with a very high destruction/removal rate. It also appears to work
well on all types of soils. Because this technology has not been widely applied, it is difficult to
predict what difficulties will arise at future sites. To be effective, it requires the soil to be screened
or ground. In 1991, the U.S. Navy will be applying BCD at a site in Guam.
In Situ Vitrification
Technology Description
In situ vitrification (ISV) uses electrical power to heat and melt contaminated soils and
sludges to form a stable glass and crystalline structure with very low leaching characteristics.
ISV (FIGURE 9) uses a square array of four electrodes inserted into the ground to establish
a current in the soil. This heats the soil to a range of 1,600 to 2,000°C, well above a typical
soil's melting point. As the melt is generated downward from the surface, organic
contaminants are destroyed by pyrolysis. The pyrolized products then migrate to the surfaces
of the vitrified zone, where they combust in the presence of oxygen. Nonvolatile inorganic
contaminants are dissolved and incorporated into the melt. The resulting product is devoid
of residual organics. A vacuum hood placed over the area collects off-gases, which are
treated before being released into the atmosphere.
5/93 41
-------
ALTERNATIVE TREATMENTS
SdU containing oroanlcs
and Inorganics
Extrem* heat
(-1600-2000eQ
In Situ
Vitrification
Vttrtfledsoll
Treated oflgasei
Spent activated cortxjn
Scrubber water from APC
FIGURE 9
IN SITU VITRIFICATION
Application
To date, only engineering and pilot-scale tests have been conducted on ISV of
hazardous wastes. Full-scale remediation of hazardous waste is expected to
commence in 1991.
A large-scale test has been conducted at Hanford, Washington, on mixed radioactive
and chemical wastes containing chromium.
Only one vendor is licensed by the U.S. Department of Energy to perform ISV.
ISV has been selected for evaluation under the SITE program.
5/93
42
-------
ALTERNATIVE TREATMENTS
• Two EPA regions have selected ISV to treat contaminated soils at three Superfund
sites contaminated with PCBs, heavy metals, organics, pesticides, and low-level
dioxins.
• Currently there is a difference of opinion concerning the fate of organic
contaminants. The issue concerns the completeness of destruction and the possibility
that organic vapors may migrate away from the soil mass that is being vitrified.
Technology Strengths
• Has the potential to destroy, remove, or immobilize all contaminant groups.
• Successfully tested for the treatment of radioactive and hazardous wastes.
• Produces a stable crystalline structure encapsulating the residual inorganic waste with
long-term durability.
Technology Limitations
• Requires off-gas collection and treatment, as well as disposal of spent activated
carbon, scrubber water, and other waste materials from the air pollution control
equipment that may be hazardous.
• May require backfilling with clean soil because volume can decrease 20-40 percent.
• Only one licensed vendor for commercial applications.
• High electrical energy consumption.
Waste Characteristics Affecting Performance
• Soil moisture, which must be driven off before melting occurs, can have a major
effect on cost.
• A second major factor affecting cost is the price of electricity.
• The capability of the system depends on two factors: (1) the capabilities of the power
supply and (2) the capacity of the off-gas system.
• The two factors that affect the ability of the power supply system are the presence
of groundwater and buried metals. Vitrification can take place in saturated soils with
low permeabilities if the melting rate is greater than the rate of recharge.
• Miscellaneous buried metal, such as drums, should have little or no effect on the
ability to process a site. A conduction path that could lead to shorting between
electrodes should be avoided.
5/93 43
-------
ALTERNATIVE TREATMENTS
The off-gas system should maintain a negative pressure to prevent any release of
contamination. Gas can be released from relatively short transient events such as the
release of entrapped air from intrusions into void spaces, penetration of a drum
containing combustible material, and intrusion into areas containing solid or liquid
combustible materials.
Treatability tests should focus on performance requirements for the off-gas treatment
system and the type and quantity of secondary waste generated. Almost all soils can
be vitrified, and this is generally not a serious consideration during treatability
testing.
TABLE 6 identifies additional characteristics impacting in situ vitrification feasibility.
5/93 44
-------
ALTERNATIVE TREATMENTS
TABLE 6
WASTE CHARACTERISTICS
Waste Type: Soils and Sludges
Technology: In Situ Vitrification
Characteristics
Impacting Process
Feasibility
Presence of groundwater
and soil permeability less
than 1 x 10'$ cm/sec
Buried metals (drums)
occupying over 90% of
linear distance between
electrodes
Loosely packed rubbish,
buried coal
Combustible liquids*
(9,600 Ib/yd of depth or
7wt%)
Combustible packages*
(1.2 yd3 or 32 ft3)
Volatile metal content
and depth
Combustible liquids
Void volumes
Reason for Potential Impact
Severity limits economic practicality
because much energy will be
expended in driving off water.
Buried metals can result in a
conductive path that would lead to
electrical shorting between electrodes.
May start underground fire.
Time-ordered limits to the capacity of
the off-gas system to contain
combustion gas. Not cumulative
capacity.
Time-ordered limits to the capacity of
the off-gas system to contain
combustion gas. Not cumulative
capacity.
Retention of volatile metals in melt is
reduced as surface is approached.
Clean soil may be placed on top to
increase depth to which off-gas
treatment may be relied on.
9,600 Ib/yd of depth or 7% by
weight.
5-6 ydj or 152 ft3.
Data Collection
Requirements
Percolation test/water
table mapping
Site mapping
Site mapping
Site mapping, analysis
for priority pollutants,
feasibility testing
Site mapping, analysis
for priority pollutants,
feasibility testing
Site mapping analysis
for Cd, Pb, Hg, As
* Concentration limits are generic in nature; individual applications need to be reviewed in
detail.
Source: Technology Screening Guide for Treatment of Soils and Sludges, EPA/540/2-88/004
5/93
45
-------
ALTERNATIVE TREATMENTS
Thermal Desorption
Technology Description
Thermal desorption technologies consist of a wide variety of processes that vaporize
volatile and semivolatile organics from soil or sludge. After desorption, the
volatilized organics may be subsequently treated in an afterburner, or condensed for
reuse or destruction in am incinerator. Air pollution control (APC) equipment may
be used to treat the exhaust gas by removing acid gas (scrubber), dust and
parti9ulates (cyclone, baghouse, or venturi), and residual organics (activated carbon
adsorption unite). Although there are no generally accepted definitions for grouping
the different types of thermal desorption, the following four terms may be used to
describe the different processes:
• Low-temperature direct-fired desorber
• Low-temperature indirect-fired desorber'
• Oxygen-free thermal processors
• In situ steam extraction
Soils containing organics
Heat(300°F-1200eF)
Thermal
Desorption
Treated residual
Recovered contaminants
Water from ARC'
Treated offgases
Partlculate control dust
Spent carbon *
* D*p«r>clrtg on toehnoiogy
5/93
46
-------
ALTERNATIVE TREATMENTS
Low-Temperature Direct-Fired Desorber
Direct fired systems use a fuel burner as a heat source which fires directly into the
primary soil heating chamber. These units operate at temperatures of less than SOOT
and are generally applicable to the treatment of nonchlorinated organics. Exhaust
gasses from the rotating cylinder pass through a dust collection system prior to
secondary combustion. OH Materials, Inc. operates a low-temperature direct-fired
desorber.
Low-Temperature Indirect-Fired Desorber
Indirectly heated systems use a heat transfer medium such as hot oil or an external
flame. Heat may be transferred through metal surfaces to the waste or by externally
heated air. Indirect heating results in greater control and lower volume of exhaust
gas. A low gas flow results in a low loading for the exhaust gas treatment and air
pollution control systems. This facilitates the use of more sophisticated emission
control equipment and the potential for treatment of chlorinated hydrocarbons.
Desorbed organics may be condensed an/or removed by carbon adsorption.
Examples of vendors for this technology include Canonie Environmental and Weston
Services, Inc. Canonie Environmental has a low-temperature thermal aeration
system, which consists of a rotating dryer that heats incoming air from 300°F to
600°F by an external flame. The system forces heated air countercurrent to the flow
of soils in a rotary drum dryer. Weston Services has a low-temperature thermal
stripping process, which uses a hollow screw mixer that is filled with hot oil to heat
the soil to approximately 450°F.
Oxygen-Free Thermal Processors
These processors operate with indirect heating at higher temperatures (>600°F).
They process soils and sludges in an oxygen-free environment that prevents
oxidation/combustion and may be used to treat PCBs. Two examples of this
technology are Chemical Waste Management's X'TRAX System and SoilTech's
AOSTRA Taciuk Processor. Both processes recover contaminants for subsequent
recycling or destruction. The X*TRAX System uses a nitrogen atmosphere to keep
the process oxygen free. Waste is treated in an indirectly heated rotating dryer at
temperatures ranging from 600°F to 900°F. The volatilized organics are carried to
a gas treatment system that condenses and recovers the contaminants. The Taciuk
process consists of a preheating chamber that operated at 300°F to 400°F, followed
by a primary pyrolysis zone that operated at 1,100°F to 1,200°F. Hydrocarbons are
desorbed and then recovered in a condenser.
In Situ Steam Extraction
This process uses hollow-stem drills to inject steam and hot air into the ground.
Volatile organics are stripped form the soil (or groundwater) and collected in a
shroud at the surface. The technology is especially applicable for volatile
5/93 47
-------
ALTERNATIVE TREATMENTS
contamination near the surface. Toxic Treatments (USA) has used their unit to treat
soil at a Superfund site. Steam (at 450°F) and hot air (at 300°F) are injected through
counter-rotating drills up to 30 feet in depth. Volatile contaminants and water vapor
are collected and removed from the off-gas stream by condensation
Application
• Currently selected for 12 Superfund sites. Several variations on the
technology exist.
• See article on status of thermal remediation in the Incineration
chapter.
• Operating at lower temperatures, these processes use less fuel than
incineration.
• Decontaminated soil still retains some organics and soil properties (it
is not an ash).
Waste Characteristics Affecting Performance
• Temperature and residence time are the primary factors affecting
performance.
• Wastes with high moisture content significantly increase fuel use.
• Fine silt and clay may result in greater dust loading to the
downstream air pollution control equipment.
5/93 48
-------
VO
TABLE 7
STRENGTHS AND LIMITATIONS OF FOUR THERMAL DESORPTION PROCESSES
H
Process;: Type
Strengths
Limitations
Low-Temperature Direct-Fired
Relatively simple
Technology consists of primary combustion,
dust collection, and afterburner
Low cost
Appropriate for nonchlorinated hydrocarbons
Limited applicability
High exhaust gas flow rate
Likely to be considered same as an
incinerator by the public
Low-Temperature Indirect-Fired
Low exhaust gas flow allows more
sophisticated air emission control equipment
Low air flow limits paniculate carryover
from primary chamber
May be used for chlorinated hydrocarbons
Afterburner not necessarily required;
condensed or adsorbed gases may be
removed offsite
Lack of direct combustion minimizes
formation of products of incomplete
combustion (PICs)
Operation at lower temperatures
may limit applicability to volatile
organics
Oxygen-Free Thermal
Potential use on PCB waste
Hydrocarbons may be collected for offsite
destruction or reuse
Closed systems eliminate exhaust gases
Lower capacity and higher cost
than low-temperature direct- and
indirect-fired units
In Situ Steam Extraction
May be used for volatile contamination near
the surface (where vacuum extraction is not
effective
Although not generally applicable
for semivolatiles, some removal
may take place
-------
ALTERNATIVE TREATMENTS
TABLE 8
WASTE CHARACTERISTICS
Waste Type: Soils and Sludges
Technology: Low-Temperature Thermal Stripping
Characteristics
Impacting Process
Feasibility
Reason for Potential Impact
Data Collection
Requirements
Presence of:
• Metals
• Inorganics
• Less volatile organics
Some processes effective only for
highly volatile organics (Henry's Law
Constant >3 x 10'3 atm-mVmole).
X*TRAX System can treat organics
with boiling points up to about 800°F
Analysis for priority
pollutants
pH
Corrosive effect on system
components
pH analysis
Presence of mercury (Hg)
Boiling point of mercury (356°C)
close to operating temperature for
process (100°C to 300°C)
Analysis for mercury
Unfavorable soil
characteristics:
• High percent of clay
or silt
• Tightly aggregated
soil or hardpan
• Rocky soil or glacial
till
• High moisture content
Fugitive dust emissions during
handling
Incomplete devolatilization during
heating
Rock fragments interfere with
processing
High energy input required.
Dewatering may be required as
pretreatment.
Grain size analysis
Soil sampling and
mapping
Soil mapping
Soil moisture content
Source: Technology Screening Guide for Treatment of Soils and Sludges, EPA/540/2-88/004
5/93
50
-------
United States Office of Emergency and Environmental
Environmental Protection Remedial Response Response
Agency Emergency Response Division Team
xvEPA
Treatment Technologies
for Superfund
Workbook
-------
TREATMENT TECHNOLOGIES FOR SUPERFUND (165.3)
WORKBOOK
CONTENTS
COMMONLY USED ACRONYMS IN HAZARDOUS WASTE MANAGEMENT 1-4
CLASS PROBLEMS:
Bulking Hazardous Waste 5-26
Nampa, Idaho 27-32
Houston, Missouri - PCP Incident 33-38
Sydney Mines Waste Disposal Site 39-49
-------
COMMONLY USED ACRONYMS IN HAZARDOUS WASTE MANAGEMENT
AA
ACGIH
AIHA
ANSI
ARAR
ARCS
ATSDR
BOAT
BM
BOD
CAA
CAG
CBD
CDC
CERCLA
CERCLIS
CERI
CFR
CHEMTREC
CHRIS
CMA
COD
COE
CRS
CWA
DE
DOA
DOD
DOE
DQI
DOJ
DOL
DOT
DQO
Assistant Administrator (EPA)
American Conference of Governmental Industrial Hygienists
American Industrial Hygiene Association
American National Standards Institute
Applicable or Relevant and Appropriate Requirement
Alternative Remedial Contracting Strategy
Agency for Toxic Substances and Disease Registry
Best Demonstrated Available Technology
Bureau of Mines
Biochemical Oxygen Demand
Clean Air Act
Cancer Assessment Group
Commerce Business Daily
Center for Disease Control
Comprehensive Environmental Response, Compensation, and Liability Act
CERCLA Information System
Center for Environmental Research Information
Code of Federal Regulations
Chemical Transportation Emergency Center
Chemical Hazard Response Information System
Chemical Manufacturers Association
Chemical Oxygen Demand
Corps of Engineers
Congressional Research Services
Clean Water Act
Destruction Efficiency
Department of Agriculture
Department of Defense
Department of Energy
Department of the Interior
Department of Justice
Department of Labor
Department of Transportation
Data Quality Objectives
5/93
1
-------
COMMONLY USED ACRONYMS IN HAZARDOUS WASTE MANAGEMENT CONT'D
ORE - Destruction and Removal Efficiency
EERU - Environmental Emergency Response Unit
EPTC - Extraction Procedure Toxicity Characteristics
EPA - Environmental Protection Agency
ERCS - Emergency Response Cleanup System
ERT - Environmental Response Team
FCO - Federal Coordinating Officer
FEMA - Federal Emergency Management Agency
FIFRA - Federal Insecticide, Fungicide, and Rodenticide Act
FIT - Field Investigation Team
FS - Feasibility Study
GAC - Granular Activated Carbon
GWA - Ground Water Act of 1987
HA - Health Assessment
HC - Hydrocarbon
HHS - Department of Health and Human Services
HRS - Hazard Ranking System
HSWA - Hazardous and Solid Waste Amendments (to RCRA, 1984)
IFB - Invitation for Bids
IUPAC - International Union of Pure and Applied Chemists
LUST - Leaking Underground Storage Tank
MCL - Maximum Contaminant Level
MCLG - Maximum Contaminant Level Goal
MSHA - Mine Safety and Health Administration
MSW - Municipal Solid Waste
NAS - National Academy of Sciences
NEAR - Nonbinding Preliminary Allocation of Responsibility
NCP - National Oil and Hazardous Substances Pollution Contingency Plan
NFPA - National Fire Protection Association
NIPSH - National Institute of Occupational Safety and Health
NOAA - National Oceanic and Atmospheric Administration
NPDES - National Pollutant Discharge Elimination System
NPL - National Priority List
NRC - National Regulatory Commission or National Response Center
5/93 2
-------
COMMONLY USED ACRONYMS IN HAZARDOUS WASTE MANAGEMENT CONT'D
NRT
NSF
NTIS
OERR
OHMTADS
O&M
ORD
OSC
OSHA
OSWER
OTA
PA
PAAT
PAC
PAH
PCDD
PCB
PCDF
PCP
PIAT
PIC
PM
POHC
POM
POTW
PRP
QA/QC
RA
RBC
RCRA
RD
RD&D
REMFIT
RFP
National Response Team
National Science Foundation
National Technical Information System
Office of Emergency and Remedial Response
Oil and Hazardous Materials Technical Assistance Data System
Operation and Maintenance
Office of Research and Development
On-Scene Coordinator
Occupational Safety and Health Administration
Office of Solid Waste and Emergency Response
Office of Technology Assessment
Preliminary Assessment
Public Affairs Assistance Team
Powdered Activated Carbon
Polycyclic Aromatic Hydrocarbons
Polychlorinated Dibenzo-p-dioxin
Polychlorinated Biphenyl
Polychlorinated Dibenzofuran
Pentachlorophenol
Public Information Assistance Team
Product of Incomplete Combustion
Project Manager
Principle Organic Hazardous Constituent
Polycyclic Organic Matter
Publicly Owned Treatment Works
Potentially Responsible Party
Quality Assurance/Quality Control
Remedial Action or Regional Administrator
Rotating Biological Contactor
Resource Conservation and Recovery Act
Remedial Design
Research Development and Demonstration
Field Investigation Team for EPA Remedial Actions
Request for Proposal
5/93
-------
COMMONLY USED ACRONYMS IN HAZARDOUS WASTE MANAGEMENT CONT'D
RI/FS - Remedial Investigation/Feasibility Study
RO - Reverse Osmosis
ROD - Record of Decision
RPM - Regional Project Manager
RQ - Reportable Quantity
RRC - Regional Response Center
RRT - Regional Response Team
SARA - Superfund Amendments and Reauthorization Act
SITE - Superfund Innovative Technology Evaluation
SQG - Small Quantity Generator
SSC - Scientific Support Coordinator
SWDA - Solid Waste Disposal Act
TAT - Technical Assistance Team
TCLP - Toxicity Characteristic Leaching Procedure
T&E - Test and Evaluation Facility
TOC - Total Organic Carbon
TSCA - Toxic Substances Control Act
TSDF - Treatment, Storage, and Disposal Facility
TUHC - Total Unburned Hydrocarbons
USCG - United States Coast Guard
USGS - United States Geological Survey
VOC - Volatile Organic Chemical or Volatile Organic Compound
5/93
-------
CLASS PROBLEM: BULKING HAZARDOUS WASTE
THE SITUATION:
A site that contains a minimum of 700 drums has been found in southwest Ohio. The land is owned
by the Hamilton County Park District. Representatives of the park district have stated that the site
is relatively inaccessible and they have no idea how the drums got there.
You have been assigned to remove the drums and dispose of them properly. Furthermore, because
the cost of removal must be minimized, you are to determine which drums you may safely bulk.
You started by preparing the site, staging the drums, and sampling each container. You assigned
a field chemist the task of field categorization. The results of the chemist's work can be found on
the following pages.
ANSWER THE FOLLOWING QUESTIONS:
1. Which of the drums may be bulked safely? Why?
2. What other information may be helpful for you to complete
your job?
3. What are your major concerns about the bulking operation?
5/93
-------
HAZARDOUS WASTE CATEGORIES
Drum ff_
Drum #_
Drum #_
Drum #_
Drum #
GROUP #1
TYPE:
Drum #_
Drum #_
Drum#_
Drum #_
Drum #
Drum #
Drum #
Drum #
Drum #
Drum #
GROUP #2
TYPE:
Drum #
Drum#
Drum#
Drum #
Drum #
Drum #
Drum #
Drum ti
Drum #
Drum #
GROUP #3
TYPE:
Drum #
Drum #
Drum #
Drum #
Drum #
5/93
-------
HAZARDOUS WASTE CATEGORIES
Drum #
Drum #
Drum #
Drum #
Drum #
GROUP #4
TYPE:
Drum #
Drum #
Drum #
Drum #
Drum #
Drum #
Drum ft
Drum #
Drum #
Drum #
GROUP #5
TYPE:
Drum #
Drum #
Drum #
Drum #
Drum #
Drum#_
Drum ti_
Drum #_
Drum #_
Drum #
GROUP #6
TYPE:
Drum #_
Drum #_
Drum #_
Drum #_
Drum #
5/93
-------
HAZARDOUS WASTE CATEGORIES
Drum #
Drum #
Drum ft
Drum #
Drum #
GROUP #7
TYPE:
Drum #
Drum#
Drum #
Drum #
Drum #
Drum #
Drum #
Drum #
Drum #
Drum #
GROUP #8
TYPE:
Drum #
Drum #
Drum #
Drum #
Drum #
DISCREPANCIES:
5/93
-------
HAZARDOUS WASTE CATEGORIES
COMMENTS:
5/93
-------
FIELD ANALYSIS WORKSHEET
1.
2.
3.
Drum Number:
Drum Type and Condition: £5 &AL. C.H
Markings or Labels:
Drum Location:
5.
7.
8.
Drum Volume:
Drum Color
Comments:
6.
Solid Heel:
9.
10.
11.
13.
14.
16.
17.
18.
20.
22.
24.
Head Space CGI: A/6
Head Space PIP: 2OOO
pH: £
Water Solubility:.
Specific Gravity:
Water Reactivity:
Flash Point:
ZOO °f
.Acid Solubility: A/£.
Beilstein:.
Cyanide:_
Other:
A/I.
12. ORP:
15. Density Gradient:
19.
21.
23.
Base Solubility :
PCB:
Sulfide:
5/93
11
-------
FIELD ANALYSIS WORKSHEET
1.
2.
3.
Drum Number:_
Drum Type and Condition: S5GAL (Ltl
Markings or Labels:.
Poof
Drum Location:
A
5.
7.
8.
Drum Volume:.
Drum Color
Comments:
6.
Solid Heel:
9.
10.
11.
13.
14.
16.
17.
18.
20.
22.
24.
Head Space CGI: ^
Head Space PIP: /£
pH:
-A/0 &AAIA/G-
Water Solubility:_
Specific Gravity: /
Water Reactivity: A/O
Flash Point: > ZOO V
Acid Solubility:
Beilstein: A/ K,
Cyanide: A/
Other:
12. ORP: 3%Q
15. Density Gradient:
19. Base Solubility: M £.
21. PCB:_
23. Sulfide:
5/93
12
-------
FIELD ANALYSIS WORKSHEET
1.
2.
3.
Drum Number:.
Drum Type and Condition
Markings or Labels.
Drum Location:
*/O A/f
5.
7.
8.
Drum Volume:.
Drum Color
Comments:
6.
Solid Heel:
9.
10.
11.
13.
14.
16.
17.
18.
20.
22.
24.
Head Space CGI:
Head Space PID:.
pH: i
A/fe
A/O
/
Water Solubility:.
Specific Gravity:,
Water Reactivity:.
Flash Point: > ZOO °f
Acid Solubility:
Beilstein: A/ ^.
Cyanide:_
Other:
12. ORP:
-------
FIELD ANALYSIS WORKSHEET
1.
2.
3.
5.
7.
8.
Drum Number:
Drum Type and Condition:
Markings or Labels: /.c
Drum Location:
Drum Volume:.
Drum Color &AC.Z
Comments:
r OZ.L "
6.
Solid Heel:
9.
10.
11.
13.
14.
16.
17.
18.
20.
22.
24.
Head Space CGI: /OO
Head Space PIP: 2.OOQ
pH: 13.
Water Solubility:_
Specific Gravity :_JI
Water Reactivity:_
Flash Point: >HOr
Acid Solubility: A/O
Beilstein:.
Cyanide:_
Other:
A/1.
12. ORP:
15. Density Gradient:.
19.
21.
23.
Base Solubility: A/0
PCB: A/- &.
Sulfide:
5/93
14
-------
FIELD ANALYSIS WORKSHEET
1.
2.
3.
5.
7.
8.
Drum Number:
Drum Type and Condition: /2./Jsrz(L
Markings or Labels:.
S &AL
Drum Location:
Drum Volume:.
Drum Color
Comments:
A
AXUH /Saw
6.
Solid Heel:
Z5
9.
10.
11.
13.
14.
16.
17.
18.
20.
22.
24.
Head Space CGI:
Head Space PID:
pH: /
Water Solubility:.
Specific Gravity:.
Water Reactivity:
Flash Point:
Acid Solubility:.
Beilstein:
Cyanide:
Other:
Jfa
V&S
A//g.
12. ORP:
15. Density Gradient: A/OA/C
19. Base Solubility: A/ A?.
21. PCB:
23. Sulfide:
5/93
15
-------
FIELD ANALYSIS WORKSHEET
1.
2.
3.
Drum Number:
Drum Type and Condition: Oti £5 &AL
Markings or Labels:
Drum Location:
4*JA
A
5.
7.
8.
Drum Volume:.
Drum Color
Comments:
6.
Solid Heel:
9.
10.
11.
13.
14.
16.
17.
18.
20.
22.
24.
: V5 %
Head Space CGI
Head Space PIP: 2OOO
pH: _ ^.y
Water Solubility:
Specific Gravity:
/
Acid Solubility:_
Beilstein: AJ.
Cyanide:
Other:
12. ORP: A//.
15. Density Gradient: A/.
Water Reactivity:
Flash Point: < HO* f > lOQ'F
19. Base Solubility: A/0
21. PCB:
23. Sulfide:
5/93
16
-------
FIELD ANALYSIS WORKSHEET
1.
2.
3.
Drum Number:
Drum Type and Condition:
Markings or Labels: A/QA/C
&AL
&A&A&C.C
Drum Location:
A
5.
7.
8.
Drum Volume:.
Drum Color
Comments:
35-
6.
Solid Heel:
9.
10.
11.
13.
14.
16.
17.
18.
20.
22.
24.
Head Space CGI:.
Head Space PIP:
oH:
Water Solubility:
Specific Gravity: /
A&0\/^
Water Reactivity:
Flash Point: > 2OO °-r
Acid Solubility:
Beilstein:
Cyanide:
Other:
12. ORP: V/O
15. Density Gradient:
19. Base Solubility:.
21. PCB:_
23. Sulfide:
5/93
17
-------
FIELD ANALYSIS WORKSHEET
1.
2.
3.
5.
7.
8.
Drum Number: _
Drum Type and Condition:
Markings or Labels: (jO£*.OSZ. l/€
55 fi-AL
Drum Location:
XT
Drum Volume:.
Drum Color
Comments:
6. Solid Heel: A/QA/C
9.
10.
n.
13.
14.
16.
17.
18.
20.
22.
24.
Head Space CGI:.
Head Space PIP:
pH:__/V
-------
FIELD ANALYSIS WORKSHEET
1.
2.
3.
Drum Number:
Drum Type and Condition: £t-1 65 &AL
Markings or Labels:
Drum Location:
5.
7.
8.
Drum Volume: 35
Drum Color
Comments:
6. Solid Heel: A>6?A/£
9.
10.
11.
13.
14.
16.
17.
18.
20.
22.
24.
Head Space CGI: /OO
Head Space PIP:
pH:
Water Solubility:
Specific Gravity: /
Water Reactivity: A/QA/£
Flash Point: < /GO °f
Acid Solubility:
Beilstein:
Cyanide:
Other:
12. ORP: 3?O
15. Density Gradient: M?A/£
19. Base Solubility:
21. PCB:
23. Sulfide:
5/93
19
-------
FIELD ANALYSIS WORKSHEET
1.
2.
3.
5.
7.
8.
Drum Number:
Drum Type and Condition: I// &OOA 55 GrtL.
Markings or Labels:.
Drum Location:
Drum Volume:
Drum Color
Comments:
A
6. Solid Heel:_/UW£
9.
10.
11.
13.
14.
16.
17.
18.
20.
22.
24.
Head Space CGI: < /
Head Space PIP: 2.OOO
PH: 7Q
Water Solubility: A/3
Specific Gravity: ^ /
Water Reactivity: AA &
Flash Point: > ZOO °f
Acid Solubility:
Beilstein:
Cyanide:
Other:
12. ORP: 3ZO
15. Density Gradient:
19. Base Solubility:
21. PCB:
23. Sulfide:
5/93
20
-------
FIELD ANALYSIS WORKSHEET
1.
2.
3.
Drum Number:.
Drum Type and Condition: 55 &AL
Markings or Labels:
CM
Drum Location:
5.
7.
8.
Drum Volume:
Drum Color
Comments:
Solid Heel:
9.
10.
11.
13.
14.
16.
17.
18.
20.
22.
24.
Head Space CGI:
Head Space PID:
PH: ?-
i
Water Solubility:,
Specific Gravity:_
Water Reactivity:.
Flash Point: > 2JOO *f
Acid Solubility:.
Beilstein: // K. •
Cyanide:
Other:
12. ORP:
15. Density Gradient:
19.
21.
23.
Base Solubility:
PCS:
Sulfide:
5/93
21
-------
FIELD ANALYSIS WORKSHEET
1.
2.
3.
Drum Number:
Drum Type and Condition: 55 CrAL
Markings or Labels:.
Drum Location:
A
/&*€
5.
7.
8.
Drum Volume:.
Drum Color
Comments:
6.
Solid Heel:
9.
10.
11.
13.
14.
16.
17.
18.
20.
22.
24.
Head Space CGI: /OP*?*
Head Space PIP: 2QOO
pH: 7. /
Water Solubility:
Specific Gravity: '
12. ORP: 3XO
15. Density Gradient: A/OA/£
Water Reactivity:
Flash Point: > IQP 'f
-------
FIELD ANALYSIS WORKSHEET
1.
2.
3.
5.
7.
8.
Drum Number:
Drum Type and Condition:^/ 65/j
Markings or Labels: A/OM&
Drum Location:
/O
Drum Volume:.
Drum Color
Comments:
Solid Heel:
9.
10.
11.
13.
14.
16.
17.
18.
20.
22.
24.
Head Space CGI:
Head Space PIP:
pH: _ ^
< / n
Water Solubility: A/0
Specific Gravity: '
Water Reactivity:
Flash Point: > ZOO °r
Acid Solubility:
Beilstein:
Cyanide:
Other:
12. ORP:
15. Density Gradient:
19. Base Solubility:
21. PCB:
23. Sulfide:
5/93
23
-------
FIELD ANALYSIS WORKSHEET
1.
2.
3.
5.
7.
8.
Drum Number: //A/003
Drum Type and Condition: 5*5 CrAL 3T&C.L CH
Markings or Labels:
Drum Location:
Drum Volume:
Drum Color
Comments:
6. Solid Heel: A/Ofi/6.
9.
10.
11.
13.
14.
16.
17.
18.
20.
22.
24.
Head Space CGI: &O A
Head Space PIP: 2-OOO
pH: 6-O
Water Solubility:
Specific Gravity:
A/O
Water Reactivity:_
Flash Point: >/OO °:
Acid Solubility: A/O
Beilstein:
Cyanide:
Other:
12. ORP:
15. Density Gradient:
*f
19.
21.
23.
Base Solubility: A/Q
PCB:
Sulfide:
5/93
24
-------
FIELD ANALYSIS WORKSHEET
1.
2.
3.
5.
7.
8.
Drum Number:,
Drum Type and Condition:
Markings or Labels: /Jo/J£
ID
Drum Location:
Drum Volume:.
Drum Color
Comments:
/
6. Solid Heel: A/QA/t.
SotrA
9.
10.
11.
13.
14.
16.
17.
18.
20.
22.
24.
Head Space CGI: < /
Head Space PIP: A/*fJ6
pH: /ff5o6AA g £.Z
Water Solubility:.
Specific Gravity: /
Water Reactivity: A/0
Flash Point:
Acid Solubility:
Beilstein:_
Cyanide:_
Other:
///e
12. ORP:
15. Density Gradient:
19. Base Solubility:
21. PCB:
23. Sulfide:
5/93
25
-------
FIELD ANALYSIS WORKSHEET
1.
2.
3.
Drum Number:
ANfoo I
3O &AL SrGC.t
Drum Type and Condition:.
Markings or Labels. AetQMTAHX*lATl*lGr
_^ AS-Z
Drum Location:
5.
7.
8.
Drum Volume:.
Drum Color
Comments:
6.
Solid Heel:
9.
10.
11.
13.
14.
16.
17.
18.
20.
22.
24.
Head Space CGI: ^ >
Head Space PIP: 3
pH: /^^A/. - 5.5"
Water Solubility:
Specific Gravity:
/
Water Reactivity:
Flash Point:
Acid Solubility: //<<•
Beilstein:
Cyanide:
Other:
12. ORP:
72^7
15. Density Gradient:
19.
21.
23.
Base Solubility: A/A-
PCS: A/1-
Sulfide:
A//.
5/93
26
-------
CLASS PROBLEM: NAMPA, IDAHO
THE SITUATION:
The aquifer underlying the city of Nampa, Idaho, has been contaminated with a light petroleum-type
material for a number of years. During certain times of the year, the water table is close to the
ground surface, causing these materials to collect in basement sumps and fumes to permeate buildings
in the downtown area.
Using the information supplied, design a simple groundwater study that will determine:
1. Direction of groundwater flow.
2. The estimated extent of contamination by the petroleum
materials.
3. The possible source.
THE APPROACH:
Plot on the accompanying map the height of the water column in each well (see TABLE 1 for well
data). Establish a few equipotential surface lines. Assuming that the groundwater will flow in
pathways at right angles to these equipotential lines, determine general flow direction. (The result
is a very simplified flow net.)
Well data in TABLE 1 will also provide information concerning observed contamination at each well
point. Using this information, estimate the extent of contamination and draw a rough outline on the
map of the plume.
After establishing the location of the contamination and the possible source or sources, prepare a
general approach to recovery.
1. What are the treatment concerns for the water recovered with the oil?
2. What are discharge considerations for this wastewater?
3. What kind of simple treatments might be applicable to render this wastewater
suitable for discharge?
4. Are there any wastewater or oil storage difficulties?
5/93 27
-------
CLASS PROBLEM: NAMPA, IDAHO
ABBREVIATIONS USED ON MAP: A - Trumbull Oil
B - Town Pump
C - Sinclair
D - Chevron
E - Union
F - Fleetway
G - Ace Oil
5/93 28
-------
CLASS PROBLEM: NAMPA, IDAHO
TABLE 1
DATA ON TEST WELLS
Well Number
Water Column Elevations (ft)
Comments
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
2,474.77
2,474.34
2,473.74
2,473.50
2,473.44
2,473.19
2,473.95
2,474,24
2,475.64
2,475.27
2,475.33
2,474.94
2,475.53
2,476.05
2,476.03
2,477.60
2,478.44
2,477.58
2,476.83
2,476.55
2,477.06
2,477.98
2,477.68
2,477.70
2,475.78
Nothing observed
Nothing observed
HNU down hole 160
HNU down hole 150
HNU down hole 6
HNU down hole 6
HNU down hole 130
HNU down hole 130
Nothing observed
HNU down hole 150
HNU down hole 120
Nothing observed
Nothing observed
HNU in mud 200
Nothing observed
HNU down hole 8
Nothing observed
Nothing observed
HNU down hole 100
Nothing observed
Oily
Nothing observed
Nothing observed
Nothing observed
Running water
5/93
29
-------
CLASS PROBLEM: NAMPA, IDAHO
TABLE 1
DATA ON TEST WELLS
Well Number
Water Column Elevations (ft)
Comments
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
51
2,474.27
2,475.40
2,474.64
2,473.80
2,473.40
2,473.06
2,473.23
2,472.36
2,472.36
2,472.56
2,472.90
2,473.08
2,472.18
2,472.99
2,472.36
2,471.43
2,472.66
2,472.51
2,471.89
2,472.16
2,479.00
2,479.86
2,481.75
2,478.09
2,471.34
Nothing observed
HNU down hole 15
Nothing observed
Nothing observed
Nothing observed
HNU down hole 120
Nothing observed
Nothing observed
HNU down hole 50
HNU down hole 50
HNU in mud 200
Nothing observed
Black stained sand
Oily sand
Nothing observed
Nothing observed
Black stained sand
Nothing observed
Nothing observed
HNU in mud 50
Nothing observed
Nothing observed
Nothing observed
Nothing observed
Nothing observed
5/93
30
-------
CLASS PROBLEM: NAMPA, IDAHO
TABLE 1
DATA ON TEST WELLS
Well Number
Water Column Elevations (ft)
Comments
52
S7
S8
Nl
N2
N3
N4
N5
N6
N7
N8
N9
N10
Nil
2,473.77
2,474.36
2,471.99
2,470.34
2,470.16
2,467.31
2,467.70
2,467.44
2,467.47
2,467.45
2,467.00
2,468.35
2,467.07
2,465.00
Nothing observed
Nothing observed
Nothing observed
Nothing observed
HNU down hole 15
HNU down hole 6
Nothing observed
Nothing observed
Nothing observed
Nothing observed
HNU down hole 100
Nothing observed
Nothing observed
Nothing observed
5/93
31
-------
ISl
• 49
(pf
48
•
(
•47
(C\17
~ .22
^- 1^
•18
23
•
•
•
•
•
•46
00 .15 ,13
•21
.14
20
25 10
• 9
27
28
29
11
•
2
1? 26
.8
•1
4
•
• '3
•
,7
5
FURNITURE
/ ©
s-
•ORL
/ 30 37
t • '
31 36
•
' 35
•
•
*
•
40
• r
43
k
'42
• . ..
45
•
44
34 38 39
H-+++-H-H-H III! MHHH-hHH-HH-H-HH-f-t-H-|-IH-l-|-|-l-l-l-H-HH-{-H-f-{-M-f-l
-H I i I I i i I I I -i i i I H
HMH-IM-l-{H--{-|-H-[-iHH-l-|-l-}-l-[-H-H-T--r-|-f-l-l I I I I H
i i i i i HH
Well locations
INDIAN CREEK
NAMPA, IDAHO
-------
CLASS PROBLEM: HOUSTON, MISSOURI - PCP INCIDENT
INCIDENT:
An aboveground storage tank collapsed from its supports, causing breach of the tank and subsequent
discharge of a large amount of oil containing a high concentration of pentachlorophenol (PCP).
LOCATION:
Houston Chemical Co., two and one-half miles south of Houston, Missouri.
BACKGROUND:
A representative of the Cairo Treating Plant of Houston Chemical Co. in Houston, Missouri, called
the EPA Regional Office at 8:30 a.m.', June 18, 1979, to report a four-day-old spill of an estimated
15,000 gallons of oil and pentachlorophenol (5-percent PCP by volume). This PCP/oil mixture is
used by the Cairo Plant as a preservative in a wood treatment process. The initial spiller's report
stated that the material had been contained by a dike and was being removed by a pump truck. The
spiller reported no problem with the cleanup and no potential for the product to enter drinking water
supplies.
At approximately 4:30 p.m., June 18, a Missouri conservation commission agent called the regional
spill line and reported that an estimated 90 percent of the spilled product had escaped the plant
containment structures and had been temporarily caught in a small farm pond, a tributary to Hog
Creek and Big Piney River. The pond reportedly was covered with a layer of PCP/oil and had very
little freeboard to prevent discharge if rain, which was predicted, occurred.
The threat of heavy rains and subsequent contamination of public drinking water supply (Big Piney
River) mandated immediate action. On June 19, representatives of the U.S. Environmental
Protection Agency; U.S. Coast Guard; Occupational Safety and Health Administration; U.S. Food
and Drug Administration; U.S. Army Corps of Engineers; Missouri Department of Health, Natural
Resources, Conservation, and Highways; and a commercial cleanup contractor met in Houston to
determine the course of action to be followed to alleviate the threat to public health and the
environment.
An early morning investigation revealed that the large storage tank (21,300 gallons) collapsed after
being filled to capacity from a nearby mixing plant (see map). The west (front) end of the tank
struck the ground, and the drain valve and pipe sheared off, causing continuous discharge. Total
spillage was estimated at 15,000 gallons. The PCP/oil ran down a dirt driveway. Some of the
materials filled the holding pit behind the mixing facility and overflowed through a drain pipe and
5/93 33
-------
CLASS PROBLEM: HOUSTON, MISSOURI - PCP INCIDENT
into a drainage ditch. The remainder of the mixture ran down the drive into the same drainage ditch.
The PCP/oil ran down the ditch, through a culvert, under a side road, then through a culvert under
U.S. Route 63 into a water catch basin. The material then traveled underground approximately 75
feet, leaching into a small pond (7/10 of an acre, approximately 250 feet long, 122 feet wide, and
6 Vi feet deep). At the time of the investigation, the pond was covered with a Vi-inch layer of
PCP/oil. Under high water conditions, the water overflows the pond at the northeast corner
spillway, draining into Hog Creek, then to the Big Piney River. Further studies provided the
following information:
• There was a total fish kill in the pond
• The tank was located in an undiked area, at the top of the ridge to the west
• The pond is at a 20-foot-lower elevation than the spill site
• The well located just south of the mixing facility was fouled by the PCP/oil
• There are a number of residential wells in the vicinity
• Pond temperature is 68°F.
Representatives of the Missouri Department of Conservation and the U.S. Fish and Wildlife Service
recommended a treatment level of 10 ppb in order to restore conditions for aquatic life.
TASK:
1. Develop a control and cleanup plan for this situation.
2. Using the information provided in the scenario and supplemental fact sheet,
solve the following problems:
a. Determine the volume in gallons of water in the pond.
b. Determine the volume in gallons of spilled material on the
pond surface.
c. Determine the percentage of the spilled material collected
on the surface of the pond.
5/93 34
-------
CLASS PROBLEM: HOUSTON, MISSOURI - PCP INCIDENT
d. Determine the amount of PCP, in grams, in the pond water.
What assumptions, if any, must you make?
e. Under laboratory conditions it has been determined that one
brand of activated carbon has an adsorption capacity of 40
mg/g carbon. How much of this carbon is required to
remove all the PCP in the pond water? (Calculate the
maximum that can be dissolved under optimum conditions.)
CONVERSION FACTORS:
1.06 quarts = 1 liter
1 gallon = 0.1337cu. ft.
2.2 pounds = 1 kilogram
Solubility of PCP in water = 14 mg/1 @'68°F.
SUPPLEMENTARY FACT SHEET:
A report of a "Penta" spill in Houston, Missouri, was received on the EPA Action Line in the
Kansas City office. The information was immediately given to the emergency response section.
Phenol is a compound produced from coal tar and is used in making explosives and synthetic resins.
It is a strong corrosive poison. Pentachlorophenol is produced by mixing phenol with chlorine. It
is used as a wood preservative to lengthen the life of structural wood products. Its sodium salts are
widely used as pesticides.
EPA was concerned about the chemical getting into drinking water supplies because ingestion causes
lung, liver, and kidney damage.
EPA became involved when conversations with the spiller and a Missouri conservation agent
revealed that the actions taken by the spiller were inadequate to protect public health.
The Regional Response Team was activated to evaluate the situation and determine whether a federal
cleanup would be necessary to protect public health and environmental resources.
The Regional Response Team is composed of representatives from federal and state agencies who
can contribute to the identification of hazards and cleanup actions.
5/93 35
-------
CLASS PROBLEM: HOUSTON, MISSOURI - PCP INCIDENT
Federal and state involvement is recommended for spills from 10 pounds up.
The contaminated soil must be removed because the chemical will remain toxic for an indefinite
period of time.
The contaminated soil will be disposed of at Bob's Home Service Landfill in Wright City, Missouri.
This is (was) an approved permitted landfill.
If the spiller had provided for onsite spill retention, the cost of the cleanup would have amounted
to approximately $5,000. Without such precautions, the estimated cleanup is $500,000.
5/93 36
-------
vo
UJ
North
Mtxina bld£. \Storage
tank v. 15,000 f>al
1 '
o I «-
'cylindrical
storage tank
21,300 gal-
to Houston,
Missouri
1.5 miles
Water catch basin
(man-made)
Dry drainage ditch
old U.S. 63
O
oo
V)
8
O
W
g
2
C/3
O
o
2:
n
MAP FOR HOUSTON, MISSOURI - PCP INCIDENT
-------
CLASS PROBLEM: SYDNEY MINES WASTE DISPOSAL SITE
HISTORY:
The site is located in Hillsborough County, Florida, on land that was stripmined for phosphate ore
during the 1930s and 1950s, and then abandoned. Hillsborough County leased the site in 1973 as
a permitted solid waste disposal facility and constructed a sludge pond for disposal of grease trap,
septic waste, and waste oil. A second pond was added in 1979 to separate the disposal of septic
waste from oil waste. These two surface impoundments are the primary disposal facilities onsite.
The septic waste pond occupies 6,070 square meters (1.5 acres); the smaller oil waste pond covers
2,430 square meters (0.6 acres). The disposal area of concern covers approximately 10 acres in a
mining area of over 100 acres.
The county ceased waste disposal activities at the site in November 1981 and retained a consultant
in June 1982 to assist in filing a site closure application with the Florida Department of
Environmental Regulation. Previous site investigations and additional intensive sampling indicated
toxic organics were present in the disposal ponds and the perched groundwater table below the
ponds. The consultant was retained to provide engineering design and construction management for
remedial activities.
The waste disposal ponds are located above an area that was mined twice and reclaimed by
backfilling with phosphatic clay wastes called slimes. Perimeter retention dikes were constructed
during mining operations to form clay, slime-settling ponds. The highly impermeable slimes are
covered with tailing sands from 1 to 6 meters (20 feet) deep. A perched water table recharged by
rainfall has developed in the sand tailings, as shown in the figure below. This perched water table
is not used for water supply. It is separated from the Floridian aquifer, which lies approximately
90 meters (300 feet) below land surface, by the clay slimes and the natural clay strata that underlie
the clay slimes.
The disturbed, rather than natural, geological setting of the waste disposal ponds has created unique
circumstances of contaminant migration. The perched water table has no outlet for groundwater
flow, except during rainy periods when a rising water table allows flow into the northern settling
pond dike wall.
Surface cleanup is the most complex portion of the Sydney Mine site closure. Waste disposal pond
contents, including oil, sludges, and contaminated bottom sands, must be treated and/or disposed of
in an acceptable and cost-efficient manner.
The septic waste pond covers approximately 1.5 acres, is 200 feet wide by 300 feet long, and is 10
feet deep in tailing sands 20 feet thick. Because of drought conditions, free liquids have evaporated,
leaving concentrated toxic organic sludge nearly 5 feet deep. Sampling of pond contents (EP Tox
and heavy metals and pesticides) showed wastes to be within RCRA toxicity limits. Oil
contamination is visible in the sand. Lateral seepage is limited to 1 foot and vertical seepage is
approximately 5 feet.
5/93 39
-------
CLASS PROBLEM: SYDNEY MINES WASTE DISPOSAL SITE
Perched
Water Table
Contaminant Septic Wastes
Flow Pond
\ Oil Waste Pond I
/ /- N 1
Clay Slimes
/' / / Unmiried Impermeable Layer
.'S'S.tfst' •
-^
The oil disposal pond is deeper than the septic waste pond and extends almost into the clay slimes.
The pond is 150 feet wide, 175 feet long, and 18 feet deep. There are waxes, emulsified oils, VOC-
contaminated waters, and floating oils in the pond with an estimated 2 feet of sludge in the bottom.
Liquids (including the sludge) are 10 feet deep in the pond. Lateral seepage is limited to 1 foot and
vertical seepage extends to the clay slimes.
INSTRUCTIONS PART I:
1. Estimate the volume of sands and sludges to be excavated.
a. Use a depth of 20 feet for the tailing sands.
b. The septic pond is empty of water but contains 2 feet of
sludge.
5/93
40
-------
CLASS PROBLEM: SYDNEY MINES WASTE DISPOSAL SITE
c. The oil pond contains liquids, floating product, and 2 feet
of sludge. Liquids will go to a separator. The separator
process will generate 2 tons of sludge that will subsequently
be disposed of with the solids.
d. Use a lateral seepage distance of 1 foot.
e. Vertical seepage can be estimated to extend 5 feet.
2. Using a soil density of 118 pounds per cubic foot, calculate the tonnage of
excavated soil.
3. Determine the cost of treatment and disposal for the following alternatives:
a. Excavation costs for all alternatives
can dig 1,200 cu. yds. per day
costs $1,970 per day
b. Landfilling
costs per ton shipping $75.00
cost per ton placement $100.00
analysis costs $30,000
continued responsibility
c. Stabilization and in situ placement
costs per ton $150.00
analysis cost $20,000
continued monitoring, extra costs
continued responsibility
d. Incineration onsite
cost per ton $190.00
includes ash disposal and setup.
4. Based on cost and other concerns, select a treatment method(s).
5/93 41
-------
CLASS PROBLEM: SYDNEY MINES WASTE DISPOSAL SITE
A 10-acre area surrounding the waste ponds is isolated by the construction of a slurry trench cutoff
wall. The total depth of tailing sands is 20 feet, but the saturated thickness is only 10 feet. The
ultimate porosity or volume of voids to total volume is 0.40.
INSTRUCTIONS PART II:
1. Using the saturated volume and the porosity, calculate water content.
2. There are 40 pumps providing an average of 6 gpm to an equalization tank
of 200,000 gal. Calculate detention time in the tank (volume/flow rate =
time).
The following pages contain information of the groundwater contaminant constituents, chemical
information, a list of conditions concerning treatment, and four treatment descriptions. Construction
costs, operation and maintenance costs per unit, and efficiencies are provided for each.
3. Using efficiencies, select a treatment unit or units to treat the groundwater
wastestream to the specified discharge limits.
1 ppb volatile organics or detection limits
10 ppb extractable organics or detection limits
design of each unit has been preselected
4. Calculate the annual cost of treatment.
spread construction costs over 5 years.
flow rate is 200,000 gpd (5 years of treatment)
cost analysis is greatly simplified and not demonstrative of
a complete cost-benefit analysis
CONDITIONS:
1. Treatment units in packet were selected to meet the ARARs in general sense.
2. Unit design features such as size, retention time, overflow rates, and other
parameters were preselected. Design of the units themselves would be an
effort beyond the scope of this course.
5/93 42
-------
CLASS PROBLEM: SYDNEY MINES WASTE DISPOSAL SITE
3. Cost factors were calculated using averages and only gross costs are
provided for simplicity. Actual cost-benefit comparisons are much more
complex and would be too time-consuming for the course.
4. All removal efficiencies were arbitrarily selected from averages and would
not necessarily hold true for a specific wastestream.
5. The selection of appropriate treatment systems is much more complex than
is possible to simulate in detail within the time constraints of this course.
However, every effort has been made to provide a problem that covers the
most important aspects of the process.
INFLUENT FLOW RATE
200,000 GPD
DISCHARGE LIMITS
1 ppb volatile organics and
10 ppb extractable organics and pesticides or detection
limits
DURATION OF TREATMENT
Five years estimated duration would naturally vary for
different treatment systems, but the time has been
established for the problem set to simplify
comparisons.
5/93
43
-------
CLASS PROBLEM: SYDNEY MINES WASTE DISPOSAL SITE
DISCHARGE WILL BE THROUGH AN ONSITE IRRIGATION SYSTEM
Irrigation will be over the site, providing a flush of the contaminated area. Concentrations of
contaminants in the influent will decrease as treatment progresses. This decreasing load would make
it necessary to design considerable flexibility of treatment into each unit. For our purposes, assume
that the design of each unit takes this need into account.
1. Only construction and operation and maintenance costs will be considered.
Salvage, depreciation, replacement, and interest costs will be ignored.
2. Suspended solids content in the groundwater wastestream is 20 ppm.
3. The solids in the oil pond waste will require removal. Oil pond waters after
oil/water separation will be included in the water treatment system.
Approximately 2 tons of sludge will be generated.
4. Design concentrations will be provided in a table and will represent the total
wastestream to be treated.
5. Discharge limits on all compounds are one ppb, and 10 ppb or detection
limits.
6. Units provided in the packet can meet necessary regulations in operation, if
not alone, then in combination with another in the packet.
DESIGN CONCENTRATIONS
Benzene 100 ng/\
Carbon Tetrachloride 100 /xg/1
Chloroform <20/*g/l
1,1-Dichloroethane 25 /ig/1
1,2-Dichloroethane 50 /ig/1
1,1-Dichloroethene 200 /ig/1
rra/w-l,2-Dichloroethene 30 /ig/1
Methylene Chloride 1000 /ig/1
1,1,1-Trichloroethane 50 /ig/1
Trichloroethylene 100 /ig/1
Toluene 500 /ig/1
Vinyl Chloride 50 /ig/1
Pentachlorophenol 250 /ig/1
2,4-D 50 /*g/l
2,4,5-TP 30 /ig/1
5/93 44
-------
CLASS PROBLEM: SYDNEY MINES WASTE DISPOSAL SITE
VOLATILE ORGANICS:
BENZENE
CARBON TETRACHLORIDE
CHLOROFORM
1,1-DICHLOROETHANE
1,2-DICHLOROETHANE
1,1 -DICHLOROETHENE
solubility - l,780mg/l
Henry's Law constant - .00559 atm-m3/mole
adsorption - 76 mg compound/g carbon
biodegradation - degradable
solubility - 800 mg/1
Henry's Law constant - 0.0241 atm-m3/mole
adsorption - 76 mg compound/g carbon
biodegradation - refractory/nondegradable
solubility - 8,000 mg/1
Henry's Law constant - 0.00278 atm-mVmole
adsorption - 1.6 mg compound/g carbon
biodegradation - refractory to nondegradable
solubility - 5,500 mg/1
Henry's Law constant - 0.00431 atm-mVmole
adsorption -
biodegradation - degradable
solubility - 8,520 mg/1
Henry's Law constant - 0.000978 atm-mVmole
adsorption -
biodegradation - degradable
solubility - 2,250 mg/1
Henry's Law constant - 0.0340 atm-m3/mole
adsorption -
biodegradation - degradable
TRANS-1.2-DICHLOROETHANE solubility - 6,300 mg/1
Henry's Law constant - 0.00656 atm-mVmole
adsorption -
biodegradation - degradable
METHYLENE CHLORIDE
solubility - 20,000 mg/1
Henry's Law constant - 0.00203 atm-m3/mole
adsorption - 2.7 mg compound/g carbon
biodegradation - degradable
5/93
45
-------
CLASS PROBLEM: SYDNEY MINES WASTE DISPOSAL SITE
1,1,1 -TRICHLOROETHANE
TRICHLOROETHYLENE
TOLUENE
VINYL CHLORIDE
solubility - 4,400 mg/1
Henry's Law constant - 0.0144 atm-m3/mole
adsorption - 155 mg compound/g carbon
biodegradation - degradable
solubility - 1,100 mg/1
Henry's Law constant - 0.0091 atm-nWmole
adsorption - 140 mg compound/g carbon
biodegradation - refractory
solubility - 515 mg/1
Henry's Law constant - 0.00637 atm-nWmole
adsorption - 147 mg compound/g carbon
biodegradation - degradable
solubility - 1.1 mg/1
Henry's Law constant - 0.0891 atm-nWmole
adsorption - trace
biodegradation - refractory
EXTRACTABLE ORGANICS:
PENTACHLOROPHENOL
solubility - 14 mg/1
biodegradation - degradable
PESTICIDES AND PCBs:
2,4-D
2,4,5-TP
solubility - 890 mg/1
biodegradation - degradable
adsorption - trace
solubility - 278 mg/1
biodegradation - refractory
adsorption - trace
5/93
46
-------
CLASS PROBLEM: SYDNEY MINES WASTE DISPOSAL SITE
CONSTRUCTION COSTS
Air stripping unit: $50,000
Steam stripping unit: $75,000
Carbon adsorption unit: $50,000
Rotating biological contactor unit: $60,000
Oil/water separation unit: $15,000 includes solids removal
Units are sized to accommodate 200,000 gpd which is the design flow rate of our system.
Costs are generic and may not reflect actual system costs in an area.
OIL/WATER SEPARATION
Oil pond is separated into free oils, sludges, and an aqueous portion. Using NaOH, alum and a
polymer, solids are flocced and settled from the aqueous portion after which they are passed through
a filter unit and pumped to the equalization tank in the groundwater treatment system. Free oil and
the hydroxide sludges are to be incinerated.
Cost per 1,000 gallons: $0.03
Concentration of contaminants is included in design concentrations for groundwater treatment system.
In actual practice, such additions to the groundwater would be a major increase in load over the
period the pond wastes are treated. The shock of the load can be dampened by dilution in the
equalization tank.
5/93 47
-------
CLASS PROBLEM: SYDNEY MINES WASTE DISPOSAL SITE
AIR STRIPPING
Limits: Compounds with a Henry's Law constant greater than 0.003 atm-m3/mole.
Efficiency: Removal to 98 percent, lower efficiencies for compounds out of limits.
Cost per 1,000 gallons: $0.04 exclusive of vapor treatment.
Design features such as tower fabrication, media selection, and air to water ratio have been
optimized for the problem.
STEAM STRIPPING
Limits: Organic compounds
Henry's Law constant of 0.0004 atm-m3/mole or greater
Vapor treatment unnecessary
Efficiency: 99 percent
Cost per 1,000 gallons: $0.80
Unit design features optimized as part of problem.
CARBON ADSORPTION
Limits: Low solubility (less than 1 or 2 percent)
Nonpolar
Adsorptive capacity 50 mg/g carbon
Concentration below 1 percent
Suspended solids less than 50 ppm
Oil and grease less than 10 ppm
Efficiency: Varies with wastestream for the purpose of this exercise. If the compound meets the
constraints in the limits listed above, the removal rate will be 90 percent. Do not consider
regeneration for the exercise.
Cost per 1,000 gallons: $0.25 if used primary unit
$0.05 if used as a polish unit
5/93 48
-------
CLASS PROBLEM: SYDNEY MINES WASTE DISPOSAL SITE
BIOLOGICAL TREATMENT
Limits: Compound degradable
Nontoxic concentrations
BOD greater than 50 mg/1
Efficiency: Degradable compound removal 95 percent
Refractory compound removal 30 percent
Cost per 1,000 gallons: $0.03
Unit is an RBC and has been sized for the problem. Removal rates of refractory compounds are
arbitrarily selected at 30 percent for the problem.
CALCULATIONS
PART 1:
A. Volume to be excavated
B. Weight of excavated sands
C. Disposal cost totals
D. Disposal method selected
PART 2:
A. Water content
B. Retention time of equalization
tank
C. Treatment unit selection
D. Annual cost of treatment
5/93
49
-------
SOURCES FOR U.S. ENVIRONMENTAL PROTECTION AGENCY DOCUMENTS
Center for Environmental Research Information (CERT) (no charge for documents)
Center for Environmental Research Information (CERI)
ORD Publications
26 West Martin Luther King Drive
Cincinnati, OH 45268
(513) 569-7562 FTS 8-684-7562
Public Information Center (PIC) (no charge for public domain documents)
Public Information Center (PIC)
U.S. Environmental Protection Agency
PM-211B
401 M Street, S.W.
Washington, D.C. 20460
(202) 382-2080 FTS 8-382-2080
Superfund Docket and Information Center (SDIC)
U.S. Environmental Protection Agency
Superfund Docket and Information Center (SDIC)
OS-245
401 M Street, S.W.
Washington, D.C. 20460
(202) 260-6940 FTS 8-382-6940
National Technical Information Services (NTIS) (cost varies)
National Technical Information Services (NTIS)
U.S. Department of Commerce
5285 Port Royal Road
Springfield, VA 22161
(703) 487-4650 l-800-553-NTIS(6847)
Superintendent of Documents
Government Printing Office
(202) 783-3238
5/93
------- |