United States
                           Environmental Protection
                             Office of
                             Solid Waste and
                             Emergency Response
September 1991
Guide  for Conducting  Treatability
Studies  under CERCLA:
Soil Washing
  Office of Emergency and Remedial Response
  Hazardous Site Control Division OS-220
                                            QUICK REFERENCE FACT SHEET
   Section 121 (b) of CERCLA mandates that EPA should select remedies that "utilize permanent solutions and alternative
treatment technologies or resource recovery technologies to the  maximum extent practicable" and that EPA should prefer
remedial actions in which treatment that "permanently reduces the volume, toxicity, or mobility of hazardous substances,
pollutants, and contaminants is a principal element." Treatability studies provide data to support treatment technology selection
and remedy implementation and should be performed as soon as it is evident that insufficient information is available to ensure
the quality of the decision. Conducting treatability studies early in the remedial investigation/feasibility study (RI/FS) process
should reduce uncertainties associated with selecting the remedy, and provide a sounder basis for the ROD. Regional planning
should factor in the time and resources required for these studies.

   This fact sheet provides a summary of information to facilitate the planning and execution of soil washing remedy selection
treatability studies in support of the RI/FS and the remedial design/remedial action (RD/RA) processes. This fact sheet follows
the organization of the "Guide for  Conducting Treatability  Studies Under CERCLA:  Soil Washing," Interim Guidance,
EPA/540/OOO/OOOA September 1991. Detailed information on designing and implementing remedy selection treatability studies
for soil washing is provided in the guidance document.

   There are three levels or tiers of treatability studies:
remedy screening, remedy selection, and remedy design. The
"Guide  for Conducting Treatability Studies Under CERCLA:
Soil Washing  Remedy  Selection" discusses the remedy
screening and remedy selection levels.

   Remedy screening studies are designed to provide a
quick and relatively inexpensive indication of whether soil
washing is a potentially viable  remedial technology. Soil
washing remedy screening studies should not be  the only
level  of testing performed before  final  remedy selection.
Remedy selection and remedy design studies will also be
required to determine if soil washing is a viable treatment
alternative for a site. The remedy selection evaluation should
provide   an  indication  that  reductions  in  contaminant
concentrations or in the volume of contaminated soil will meet
site-specific cleanup goals. It will also produce the design
information required for the next level of testing.  Remedy
design studies may be needed to optimize process design.
                          TECHNOLOGY DESCRIPTION AND
                          PRELIMINARY SCREENING

                          Technology Description

                             Soil  washing  is  a  physical/chemical  separation
                          technology  in which excavated soil is pretreated to remove
                          large objects and soil  clods and then washed with fluids to
                          remove contaminants. To  be effective, soil  washing must
                          either transfer the contaminants  to  the wash  fluids  or
                          concentrate the contaminants in a fraction of the original soil
                          volume, using size separation techniques. In either case, soil
                          washing must be used in conjunction with other treatment
                          technologies. Either the washing fluid or the  fraction of soil
                          containing most of the contaminant, or both, must be treated.

                             At the present time, soil washing is used extensively in
                          Europe and has had limited use in the United  States. During
                          1986-1989,  the technology was one of the selected source
                          control remedies at eight Superfund sites.
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    The determination of the need for and the appropriate level
of treatability studies required is dependent on the literature
information  available  on the technology,  expert technical
judgment,  and site-specific factors. Several  reports  and
electronic data bases exist that should be consulted to assist
in planning and conducting treatabilty studies as well as help
prescreen soil washing for use at a specific site. Site-specific
technical assistance is provided to Regional Project Managers
(RPMs) and On-Scene Coordinators (OSCs) by the Technical
Support Project (TSP).

Prescreening Characteristics

    Prescreening activities for the soil washing  treatability
testing include interpreting any available  site-related field
measurement data. The purpose of prescreening is to gain
enough information to eliminate from further treatability testing
those treatment technologies  which have little  chance of
achieving the cleanup goals.

    The three most important soil parameters to be evaluated
during  prescreening and remedy screening tests are the grain
size distribution, clay content, and cation exchange capacity.
Soil  washing  performance is  closely tied to  these three
factors. Soils with  relatively large  percentages  of sand  and
gravel (coarse material >2 mm in particle size) respond better
to soil washing than soils with small percentages of sand and
gravel. Larger percentages of clay and silt (fine particles
smaller than 0.25 mm) reduce soil washing contaminant
removal  efficiency.  In  general,   soil  washing  is  most
appropriate  for  soils that  contain  at  least  50  percent
sand/gravel, i.e., coastal sandy soils and soils with glacial
deposits. Soils rich in clay and silt tend to be poor candidates
for soil washing. Cation exchange capacity measures the
tendency of the soil to exchange weakly held cations In the
soil for cations in the wash solution, which will be more
strongly bound to the soil. Soils with relatively low CEC values
(less than 50 to 100 meq/kg) respond better to soil washing
than soils with higher CEC values. Early characterization of
these  parameters  and their variability  throughout the  site
provides valuable information for the  initial  screening  of soil
washing as an alternative treatment technology.

    Chemical and physical  properties  of  the contaminant
should also be investigated. Solubility in water (or other
washing  fluids)  is one  of the most  important physical
characteristics. Reactivity with wash fluids  may, in  some
cases, be another important characteristic to consider. Other
contaminant characteristics such as volatility  and density
may be important for the design of remedy screening studies
and  related residuals treatment  systems.  Speciation is
important   in  metal-contaminated  sites.   Specific  metal
compounds  should be  quantified  rather  than  total  metal
concentration for each metal present  at the site.

    There is no steadfast rule that specifies, when  to proceed
with remedy screening and when to eliminate soil washing as
a treatment technology  based on  a preliminary screening
analysis. A literature search indicating that soil washing may
not work at a given site should not automatically eliminate soil
washing from  consideration. On the other hand, previous
studies  indicating  that  pure  chemicals will be  effectively
treated  using soil  washing must be viewed  with  caution.
Chemical interactions in complex mixtures frequently found at
Superfund sites or interactions between soil and contaminants
can limit the effectiveness of soil washing. An analysis of the
existing literature, coupled with the site characterization, will
provide  the  information required to make an  "educated
decision." However, when in doubt, a remedy screening study
is recommended.

Technology Limitations

    Many factors affect the feasibility of soil washing. These
factors should be  addressed prior to the  selection of soil
washing, and prior to the investment of time and  funds in
further testing.  A  detailed  discussion  of  these factors is
beyond the scope of this document.

    Treatability studies should be performed in a systematic
fashion to ensure that the data generated can support the
remedy   evaluation   and   implementation  process.  A
well-designed  treatability study can significantly reduce the
overall uncertainty associated with the decision but cannot
guarantee that the  chosen alternative will  be completely
successful.  Care must be exercised to  ensure that the
treatability study is representative of the treatment as it will be
employed  (e.g.,  the  sample   is  representative   of  the
contaminated soil to be treated) to minimize the uncertainty
in  the decision.  The  method presented below provides a
resource-effective  means  for  evaluating  one or more

    There are three  levels  or tiers of treatability  studies:
remedy  screening remedy selection and  remedy  design.
Some or all  of the levels may be needed on a case-by-case
basis. The  need for, and  the  level of, treatability testing
required  are management decisions in which the time and
cost necessary to perform the testing are balanced  against
the risks  inherent in the  decision  (e.g.,  selection of an
inappropriate treatment alternative).  Figure 1  shows the
relationship  of three levels of treatability study to each other
and to the RI/FS process.
Remedy Screening

    Remedy screening is the first level of testing. It is used to
establish the ability of a technology to treat a waste. These
studies are generally low cost (e.g., $10,000 to $50,000) and
usually require hours to days to complete. The lowest level of
quality control is required for remedy screening studies. They
yield data enabling a qualitative assessment of a technology's
potential to meet performance goals. Remedy screening tests
can  identify  operating  standards  for  investigation during
remedy  selection  or remedy design testing.  They generate
little, if any, design or cost data, and should never be used as
the sole basis for selection of a remedy.
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                          Remedial Investigation/
                          Feasibility Study (RI/FS)
                                         of Alternatives
                                          Record of
                               Remedial Design/
                               Remedial Action
             the  -
and Technology
                             to Determine
                          Technology Feasibility
of Alternatives
                                              REMEDY SELECTION

                                               to Develop Performance
                                                   and Cost Data
  of Remedy
                                                                                 REMEDY DESIGN

                                                                              to Develop Scale-Up, Design,
                                                                                 and Detailed Cost Data
                      Figure 1. The Role of Ttreatability Studies in the RI/FS and RD/RA Process.
    Remedy screening soil washing treatability studies are
frequently skipped. Often, there is enough information about
the physical and chemical characteristics of the soil and
contaminant to allow an expert  to  evaluate  the potential
success of soil washing at a site. When performed, remedy
screening tests are jar tests. However, remedy selection tests
are normally the first level of treatability study executed.

Remedy Selection

    Remedy selection testing is the second  level  of testing.
Remedy selection tests identify the technology's performance
for a site.  These studies have a moderate cost (e.g., $20,000
to $100,000) and require several weeks to complete. Remedy
selection tests yield data that verify that the  technology can
meet expected cleanup goals, provide information  in support
of the detailed analysis of alternatives (i.e., seven of the nine
evaluation criteria), and give indications of optimal operating

    The remedy selection tier of soil washing testing generally
consists  of  laboratory  tests which   provide   sufficient
experimental controls such that a semi-quantitative  mass
balance can be achieved. Toxicity testing of the cleaned soil
is typically  employed  in  the  remedy  selection tier  of
treatability testing. The key question to be answered during
remedy selection testing is  how  much  of the soil will this
process   treat  by  either  particle  size  separation  or
solubilization to meet the cleanup goal. The exact removal
                               efficiency needed to meet the specified goal for the remedy
                               selection test is  site-specific.  In some  cases, pilot-scale
                               testing may be appropriate to support the remedy evaluation
                               of innovative technologies. Typically, a remedy design study
                               would follow a successful remedy selection study.

                               Remedy Design

                                   Remedy  design testing is  the third  level of testing.  It
                               provides   quantitative   performance,   cost,   and   design
                               information for remediating an operable unit. This testing also
                               produces remaining data required to optimize performance.
                               These studies are of moderate to high cost (e.g., $100,000 to
                               $500,000)  and require several months to  complete.  For
                               complex   sites   (e.g.,   sites  with  different  types   or
                               concentrations  of contaminants in  different  areas or with
                               different soil types in different areas), longer testing periods
                               may be required, and costs will be  higher. Remedy design
                               tests yield  data that verify performance to a  higher degree
                               than the  remedy selection  and provide  detailed  design
                               information.  They   are   performed  during   the   remedy
                               implementation phase of a site cleanup.

                                   Remedy design tests usually consist of bringing a mobile
                               treatment unit onto the site, or constructing a small-scale  unit
                               for   nonmobile   technologies.  Permit  exclusions  may
                               be   available   for   offsite   treatability  studies  under
                               certain  conditions.  The  goal  of  this  tier  of testing is
                               to  confirm  the   cleanup  levels  and   treatment times
                               specified  in  the  Work   Plan.  This  is  best  achieved
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by operating a field  unit under conditions similar to those
expected in the full-scale remediation project.

    Data obtained from the remedy design tests are used to:

        Design the full-scale unit

        Confirm the feasibility of soil washing based on target
        cleanup goals

        Refine cleanup time  estimates

        Refine cost predictions.

    Given the lack of full-scale experience with innovative
technologies,  remedy  design  testing  will generally  be
necessary in support of remedy implementation.


    Carefully planned treatability studies are  necessary to
ensure that the data generated are useful for evaluating the
validity or performance of a technology, The Work Plan, which
is prepared by the contractor when the Work Assignment is
in  place,  sets  forth the contractor's proposed technical
approach for completing the tasks  outlined  in the Work
Assignment. It also assigns responsibilities and establishes
the project schedule  and costs. The Work Plan  must be
approved by the RPM before initiating subsequent tasks. A
suggested organization of the Work  Plan is provided in the
"Guide for Conducting Treatability Studies Under CERCLA
Soil Washing."

Test Goals

    Setting goals for the treatability study is critical to the
ultimate  usefulness of the data generated. Goals must be
defined before the treatability study is performed. Each tier of
treatability study needs performance goals appropriate to that

    Remedy screening tests are not always performed for soil
washing processes. If remedy screening tests are performed,
an example of the goal for those tests would be to show that
the wash fluid will solubilize or remove a sufficient percentage
(e.g.,  50 percent)  of the contaminants  to warrant further
treatability studies. Another goal might be to  show  that
contaminant concentrations can be reduced in the >2 mm soil
fraction  by at least 50 percent, as compared to the original
soil concentrations, using particle size separation techniques.
These goals are only examples. The  remedy screening
treatabilty study goals must be determined on a site-specific

    Achieving the goals during this tier should merely indicate
that soil washing  has at least a limited chance  of success
and that further studies will be  useful. Frequently,  such
information is  available  based on  the  type of  soil  and
contaminant present at the site. Based on such information,
experts in soil  washing technology can often assess the
potential applicability of soil washing without  performing
remedy screening.
    The main objectives of the remedy selection tier of testing
are to:

        Measure the percentage of the contaminant that can
        be removed from the soil through solubilization  or
        from the  >2  mm soil  fraction  by  particle  size

        Produce the design information required for the next
        level of  testing,  should  the  remedy  selection
        evaluation  indicate  remedy  design  studies  are

        The actual goal for removal efficiency must be based
        on site- and  process-specific  characteristics.  The
        specified removal efficiency must meet site cleanup
        goals, which are based on a site risk assessment or
        on  the  applicable  or  relevant  and  appropriate
        requirements (ARARs).

Experimental Design

    A jar test is the type of remedy screening test that can be
rapidly performed in an  onsite  laboratory to  evaluate the
potential performance  of soil  washing as an  alternative
technology. Such  studies should be designated to maximize
the chances of success  at the remedy screening  level. The
object of this guidance document is not to specify a particular
remedy screening method but rather to highlight those critical
parameters which should be  evaluated during the  laboratory

    Contaminant characteristics to examine during remedy
screening  include solubility, miscibility, and dispersibility.
Properties of organic contaminants  are generally easier to
evaluate than those of inorganic contaminants. Inorganics,
such as heavy metals, can exist in many  compounds (e.g.,
oxides, hydroxides,  nitrates, phosphates, chlorides, sulfates,
and other more complex mineralized forms), which can greatly
alter their  solubilities. Metal  analyses typically provide  only
total metal   concentrations, More  detailed  analyses  to
determine chemical  speciation may be warranted.

    The liquid used  in the jar test is typically water, or water
with additives which might enhance the effectiveness of the
soil washing process. To save  time and money, chemical
analyses should not be performed on the samples until there
is visual evidence that physical separation  has taken place in
the jar tests. Jar tests can yield three separate fractions  from
the original  soil sample. These include a floating  layer, a
wastewater  with  dispersed  solids,  and  a solid fraction.
Chemical analysis can be performed  on each fraction.

    When performing the jar test, observe if any floating
materials can be skimmed off the top. Observe whether an
immiscible, oily layer forms,  either at the top or the bottom,
indicating  release of an insoluble organic  material. Observe
and time  the solids  settling rate and depth.  Sand  and
gravel  settle first,  followed by the  silt and  clay.  The
rate and the relative volume  of the  settling material will
provide  some indication of the particle size distribution
in  the  waste matrix  and the  potential  for soil washing
as  a  treatment  alternative.  Further evidence  can be
gained by  analyzing the settled and  filtered wash water
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for selected indicator contaminants  of  concern.  If simple
washing releases a large percentage  of these contaminants
into the wash water, then soil washing can be viewed favorably
and  more  detailed laboratory  and  bench tests  must  be

    Variations on the jar tests  can include the addition of
surfactants, chelants, or other dispersant agents to the water;
sequential washing; heated water washing versus cold water;
acidic  or basic wash water; and tests that include both a
wash and a rinse step. The rinse water and fine soil fraction
(<2 mm particle size) should be separated from the coarse
soil fraction (>2 mm  particle size) using  a #10 sieve. No
attempt should be made during jar tests to separate the soil
into discrete size fractions; this is done  at the bench-scale
tier of testing. Normally, only the coarse soil fraction should
be analyzed  for contamination. In general, at least a  50
percent reduction in total contaminant  concentration in the >2
mm soil fraction is considered  adequate to proceed to the
remedy selection tier. The separation of approximately  50
percent of the total soil volume  as clean soil also indicates
remedy selection studies may be warranted.

    To reduce analytical costs during  the remedy screening
tier,  a condensed  list  of known contaminants  must  be
selected  as  indicators  of performance. The  selection of
indicator analytes to track during jar testing should be based
on the  following guidelines:

        Select one or two contaminants present in the soil
       that are most toxic or most prevalent.

        Select  indicator compounds to  represent other
        chemical groups if they  are present in the soil (i.e.,
       volatile  and semivolatile organics, chlorinated and
        nonchlorinated species, etc.)

        If polychlorinated biphenyls (PCBs) and dioxins are
        known to be present, select  PCBs as indicators in
       the jar tests and analyze for them in the washed soil.
        It is usually not  cost-effective to  analyze for dioxins
        and other highly insoluble chemicals in the wash
       water generated from jar tests. Check for them later
        in the wash water from  remedy selection tests.

    Remedy selection tests require that electricity, water, and
additional equipment are available. The tests are run under
more controlled  conditions than the jar tests. The response of
the soil  sample to  variable washing  conditions is fully
characterized. More precision is used in weighing, mixing,
and particle size separation. There is  an associated increase
in QA/QC costs. Treated soil particles are separated during
the sieve operations to determine contaminant partitioning
with particle size. Chemical analyses are performed on the
sieved soil  particles as well as on the spent wash waters. The
impact of  process variables on  washing  effectiveness is
quantified. This series of tests  is  considerably more costly
than jar tests,  so only samples showing promise in  the
remedy screening phase (jar test) should be carried forward
into the remedy selection tier. If sufficient data are available in
the prescreening step, the remedy screening step may be
skipped. Soil samples showing  promise in the prescreening
step are carried forward to the remedy selection tier.
    A series of tests should  be designed that will provide
information on washing and rinsing conditions best suited to
the soil  matrix under study. The RREL data base should be
searched for information from previous studies. To establish
percent  of contaminant removal, particle size separation, and
distribution of contaminants in the washed soil, the following
should first be studied:  1) wash time, 2) wash water-to-soil
ratio, and 3) rinse water-to-wash water ratio. Following those
studies, the effect of wash water additives on performance
should be evaluated.

    Several factors must be considered in the design of soil
washing treatability studies. A remedy selection test design
should be geared to the type of system expected to be used
in the field. Soil-to-wash water ratios should be planned using
the results  from the jar tests,  if jar tests were performed. In
general, a ratio of 1 part of soil to 3 parts of wash water will be
sufficient to perform remedy  selection tests. The soil  and
wash water should be mixed on a shaker table for a minimum
of 10 minutes and a maximum of 30 minutes. The soil-to-wash
water ratio  and mix times presented here are rules of thumb
to be used  if no other information is available.

    Another factor to consider is the variability of the  grain
size distribution. Gilsen Wet Sieve devices are recommended
for remedy selection studies. Ro-Tap or similar sieve systems
may  also   be  used. Such  devices will  enhance  the
completeness and reproducibility of  grain size separation.
However, they are messy, expensive, and very noisy when in
operation. An alternate choice is to complete a series of four
to six  replicate runs under exactly the same set of conditions
to  obtain  information on  the variability of  the  grain  size
separation  technique. Variability in the separation  technique
can be evaluated by  comparing sieve screen weights across
runs and soil contaminant data for the same fractions from
each run. By identifying the range of variability associated with
repeated runs at the same conditions, estimates can be made
of the variability that  is likely to be associated with other test
runs under slightly different conditions.

    Normally, only the wash water  and  the soil particles
captured by the sieve  screen  need to  be analyzed  for
contaminants. Experience  has shown that  little  additional
contaminant removal is likely to be found in the rinse water.
Rinsing  is important  and must be included in the procedure
since  it  improves   the  efficiency  of  the  grain   size
separation/sieving  process. Rinsing separates the fine from
the coarse  material. This can result in  a cleaner coarse
fraction  and more contaminant  concentrated  in the  fine
fraction. Contaminant concentration in the rinse water may be
determined periodically (e.g.,  10 percent of the samples) to
evaluate the performance of the wash solution. However, very
little contamination is typically dissolved in the rinse solution.
Therefore,  analyses  of the  rinse solution  may have limited
value in  verifying wash solution performance.

    Initially,  only  the   coarse   soil  fraction   and  the
wash water should be analyzed for indicator contaminants.
If the  removal  of  the  indicator contaminants  confirms
that the technology  has the  potential to  meet cleanup
standards   at  the   site,   additional   analyses
should be performed. All three soil fractions and all  wash and
rinse  waters  must  be  analyzed  for all  contaminants to
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 perform a complete mass balance. The holding time of soil
fractions in the lab before extraction and analysis can be an
important consideration for some contaminants.

    The decision  on whether to perform remedy selection
testing on hot spots or composite soil samples is difficult and
must be made on a site-by-site basis. Hot spot areas should
be factored into the test plan if they represent a significant
portion of the waste site. However, it is more practical to test
the specific  waste matrix that will be fed  to the full-scale
system over the bulk of its operating life. If the character of the
soil changes radically (e.g., from day to sand) over the depth
of contamination, then tests should  be designed to separately
study system performance on each soil type.

    Additives such as  oil  and grease  dispersants  and
chelating agents can aid in removing contaminants from some
soils. However, they can also cause processing problems
downstream from the washing step. Therefore, use of such
additives should be approached with caution. Use of one or a
combination of those additives is a site-by-site determination.
Some soils do not respond well to additives. Surfactants and
chelating agents may form suspensions and foams with soil
particles during washing. This can clog the sieves and lead to
inefficient particle size separation during screening. The result
can be the recovery of soil fractions with higher contamination
than those cleaned by water alone. Such  results can make
the data  impossible  to  understand. Additives  can  also
complicate the rinse water process that might follow the soil
washing. Recent  studies have shown that  counter-current
washing-rinsing systems, incorporating the  use of hot water
for the initial wash step, offer the best performance in terms of
particle size separation, contaminant removal, and wastewater
management (treatment, recycling  and discharge).


    The Sampling and Analysis Plan (SAP) consists of two
parts-the  Field  Sampling   Plan  (FSP) and the  Quality
Assurance Project Plan (QAPjP).  A SAP is required for all
field activities conducted during the RI/FS. The purpose of the
SAP is to ensure that samples obtained for characterization
and testing are representative and that the quality of the
analytical data generated is known. The SAP addresses field
sampling, waste characterization, and sampling and analysis
of the treated wastes and residuals from the testing apparatus
or treatment unit. The SAP is usually  prepared after Work
Plan approval.

Field Sampling Plan

    The FSP component of the SAP describes the sampling
objectives; the type, location, and  number of samples to be
collected;  the sample  numbering system;  the  necessary
equipment and procedures for collecting the samples; the
sample chain-of-custody  procedures;  and the  required
packaging, labeling, and shipping procedures.
    Field samples are taken to provide baseline contaminant
concentrations and material for the treatability studies. The
sampling objectives must be consistent with the treatability
test  objectives. Because the primary objective  of remedy
screening studies is to provide a  first-cut evaluation of the
extent to which specific chemicals  are removed from the soil
or concentrated in a fraction of the soil by soil washing, the
primary sampling objectives should include, in general:

        Acquisition of samples representative of conditions
        typical of the entire site or defined areas within the
        site. Because this is a first-cut evaluation, elaborate
        statistically designed field sampling plans may not be
        required.  Professional  judgment  regarding   the
        sampling  locations should be exercised to select
        sampling  sites  that are  typical  of the  area  (pit,
        lagoon,  etc.)   or  appear   above  the  average
        concentration of contaminants in the area  being
        considered for the treatability  test.  This may be
        difficult because reliable site characterization  data
        may  not  be  available  early  in  the   remedial

        Acquisition of sufficient sample volumes necessary
        for testing,  analysis, and quality assurance and
        quality control.

    The sampling plan  for remedy selection will  be similar.
However,  because a mass  balance  is  required for  this
evaluation, a statistically designed  field sampling plan will be

Quality Assurance Project Plan

    The Quality Assurance Project  Plan should  be consistent
with  the overall objectives of the  treatability study. At the
remedy screening level the QAPjP  should  not  be overly

    The purpose of the remedy selection treatability study is
to determine whether soil washing can meet cleanup  goals
and  provide information to support the detailed analysis of
alternatives (i.e., seven  of the nine  evaluation criteria). An
example of a criterion  for this determination is removal of
approximately 90 percent of contaminants. The exact removal
efficiency specified as the goal for  the remedy  selection test
is site-specific. The suggested QC approach will consist of:

        Triplicate samples of both  reactor and controls

        The analysis  of surrogate  spike compounds in  each

        The extraction and analysis of a method blank with
        each set of samples

        The analysis of a  matrix spike in  approximately 10
        percent of the samples.
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    The analysis of triplicate samples provides for the overall
precision measurements that are necessary to determine
whether the difference is significant at the chosen confidence
level. The analysis of the surrogate spike will determine if the
analytical  method performance  is  consistent (relatively
accurate).  The  method  blank will  show  if  laboratory
contamination has had an impact on the analytical results.

    Selection of appropriate surrogate compounds will depend
on the  target  compounds identified  in the soil  and the
analytical methods selected for the analysis.


    The information and  results gathered from  the  remedy
screening are used to  determine if soil washing is a viable
treatment  option  and  to determine if  additional   remedy
selection and  remedy design  studies  are  warranted. A
reduction of approximately 50 percent of the soil contaminants
during the test indicates additional  treatability  studies are
warranted.  Contaminant  concentrations  can  also  be
determined for wash water and fine  soil  fractions. These
additional analyses add to the cost of the treatability test and
may not be needed. Before  and after concentrations can
normally be based on duplicate samples at each period. The
mean values are  compared to  assess the success of the
study. If the remedy screening indicates that soil washing is
a potential  cleanup  option then remedy selection  studies
should be performed.

    In remedy selection treatability studies, soil contaminant
concentrations  before  soil  washing  and  contaminant
concentrations  in the coarse fraction after  soil washing are
typically measured in triplicate. A reduction of approximately
90 percent in the mean concentration indicates soil washing
is potentially useful in  site remediation. A  number of  other
factors must be evaluated before deciding to  proceed to
remedy design studies.

    The final concentration of contaminants in the recovered
(clean) soil fraction, in  the fine soil fraction and wastewater
treatment sludge,  and  in the wash  water  are important to
evaluating the feasibility  of soil washing. The selection of
technologies  to  treat the  fine soil  and  wash  water
wastestreams depends upon the types and concentrations of
contaminants present. The amount of volume reduction
achieved is also important to the selection of soil washing as
a potential remediation technology.


    Literature information and consultation  with  experts are
critical factors in determining the need for and ensuring the
usefulness of treatability studies. A reference list of sources on
treatability studies  is  provided in the "Guide for Conducting
Treatability Studies  Under CERCLA" (EPA/540/2-89/058).
    It is recommended that a Technical Advisory Committee
(TAG) be  used.  This  committee includes experts on the
technology who provide technical support from the scoping
phase  of  the  treatability study through data  evaluation.
Members of the TAG may include representatives from EPA
(Region and/or ORD),  other Federal Agencies, States,  and
consulting firms.

    OSWER/ORD operate the Technical  Support Project
(TSP) which provides assistance in the planning, performance,
and/or review of treatability studies. For further information on
treatability study support or the TSP, please contact:

Groundwater Fate and Transport Technical
    Support Center
    Robert S.   Kerr  Environmental  Research  Laboratory
    (RSKERL), Ada, OK
    Contact:  Don Draper
    FTS 743-2200 or (405) 332-8800

Engineering Technical Support Center
    Risk Reduction Engineering Laboratory (RREL),
    Cincinnati, OH
    Contact: Ben Blaney
    FTS 684-7406 or (513) 569-7406


    In  addition  to  the  contacts  identified  above,  the
appropriate Regional Coordinator for each Region located in
the Hazardous Site Control Division/Office of Emergency and
Remedial  Response   or  the  CERCLA   Enforcement
Division/Office of Waste Programs Enforcement should be
contacted for additional information or assistance.


    The fact sheet and the corresponding guidance document
were prepared for the U.S. Environmental Protection Agency,
Office of Research and Development  (ORD), Risk Reduction
Engineering Laboratory (RREL, Cincinnati, Ohio, by Science
Applications  International Corporation (SAIC) under Contract
No. 68-C8-0061. Mr.  Mike Borst and Ms. Malvina Wilkens
served  as the EPA Technical Project Monitors. Mr. Jim Rawe
and Dr. Thomas Fogg served  as SAIC's Work Assignment
Managers. The project team included Kathleen Hurley, Curtis
Schmidt, Cynthia Eghbalnia, and Yueh Chuang of SAIC; Pat
Esposito of Bruck, Hartman & Esposito, Inc.; James Nash of
Chapman, Inc.  Mr. Clyde Dial  served  as SAIC's Senior

    Many  other Agency and  independent reviewers have
contributed their time  and comments by participating in the
expert review meetings and/or peer  reviewing the guidance
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