accomplished by tearing down and rebuilding the piles. In
the static windrow system piles of compost are aerated by
a forced air system (e.g., the piles are built on top of a grid
of perforated pipes). The in-vessel system involves plac-
ing the compost into a closed reactor. Aeration is accom-
plished by tumbling, stirring, and forced aeration.

2.2 PRELIMINARY SCREENING AND
TECHNOLOGY LIMITATIONS

As mentioned in Section 1, the determination of the
need for and the appropriate level of treatability studies
required depends on the literature information available
on the technology, expert technical judgment, and site-
specific factors. The first two elements — the literature
search and expert consultation — are critical in determin-
ing if adequate data are available or whether a treatabil-
ity study is needed to provide those data, The data and
information on which this decision is made should be
documented.

2.2.1 Literature/Data Base Review

Several reports and electronic data bases exist that should
be consulted to assist in planning and conducting treatabil-
ity studies as well as to help prescreen bioremediation for
use at a specific site. Existing reports include:

* Guide for Conducting Treatability Studies Under
CERCLA, Interim Final. U.S. Environmental
Protection Agency, Office of Research and
Development and Office of Emergency and
Remedial Response, Washington, D.C.
EPA/540/2-89/058, December 1989.

* Guidance for Conducting Remedial Investigations
and Feasibility Studies Under CERCLA, Interim
Final. U.S. Environmental Protection Agency,
Office of Emergency and Remedial Response,
Washington, D.C. EPA/540/G-89/004, October
1988.

+ Superfund Treatability Clearinghouse Abstracts.
USS. Environmental Protection Agency, Office of
Emergency and Remedial Response, Washington,
D.C. EPA/540/2-89/001, March 1989.

* The Superfund Innovative Technology Evaluation
Program: Technology Profiles. U.S. Environ-
mental Protection Agency, Office of Solid Waste
and Emergency Response and Office of Research

and Development, Washington, D.C.
EPA/540/5-90/006, November 1990.

« Summary of Treatment Technology Effectiveness
for Contaminated Soil. U.S. Environmental
Protection Agency, Office of Emergency and
Remedial Response, Washington, D.C., 1989 (in
press).

* Technology Screening Guide for Treatment of
CERCLA Soils and Sludges. U.S. Environmental
Protection Agency. EPA/540/2-88/004, 1988.

Currently, RREL in Cincinnati is expanding its Superfund
Treatability Data Base. This data base will contain data
from all treatability studies conducted under CERCLA. A
repository for treatability study reports will be maintained
at RREL in Cincinnati. The contact for this data base is
Glenn Shaul at (513) 569-7408.

ORD headquarters maintains the Alternative Treatment
Technology Information Center (ATTIC), a comprehen-
sive, automated information retrieval system that integrates
hazardous waste data into a unified, searchable resource.
The intent of ATTIC is to provide the user community
with technical data and information on available alterna-
tive treatment technologies and to serve as an initial deci-
sion support system. Since ATTIC functions as a focal
point for users, it facilitates the sharing of information
within the user community and creates an effective net-
work of individuals and organizations involved in hazard-
‘ous waste site remediation.

‘The information contained in ATTIC consists of a wide
variety of data obtained from Federal and state agencies.
The core of the ATTIC system is the ATTIC Data Base,
which contains abstracts and executive summaries from
over 1200 technical documents and reports. Information
in the ATTIC Data Base has been obtained from the fol-
lowing sources:

* The Superfund Innovative Technology Evaluation
(SITE) Program

¢ California Summary of Treatment Technology
Demonstration Projects

* Data Collected for the Summary of Treatment
Technology Effectiveness for Contaminated Soil

+ North Atlantic Treaty Organization (NATO)
International Data

* Innovative Technologies Program Data



Section 3 of the QAP)P, therefore, should contain a cred-
ible plan for subsampling the material for the remed:
screening treatability study. Also, if the reactor contents
are sacrificed for analysis, the methods for aliquoting the
residual material in each reactor for different analyti
methods must be described.

This section should also describe or reference an appropriatt
analytical method and a standard operating procedure for
implementing the analytical method for each type of critical
Measurement to be made. In addition, the calibration proce:
dures and frequency of calibration should be discussed

referenced for each analytical system, instrument, device, or
technique used to obtain critical measurement data.

The methods used for analyzing the treatability study
samples should be the same as those used for chemic:
characterization of field samples. Preference should
given to’ methods in “Test Methods for Evaluating el
Waste.” @ If applicable, methods other than GC/M:
methods are recommended to conserve costs.

5.2.4 Approach to QA/QC

The treatability study is designed to compare the results of}
a biological reactor to an inhibited control reactor over al
period of time. Replicate samples (three) are taken of both!
experimental setups at T,, T,, and at least a T,. The
inhibited control is run and analyzed to account for losses|
of the target compounds due to any cause other than bio-
degradation (e.g., volatilization, adsorption).

The intended purpose of this study is to determine if|
the concentration of the target compounds decreases at
least 20 percent in the biological reactor compared to

the inhibited control at an 80 percent confidence level.
Only the relative accuracy of the analytical measure-
ments and the overall precision of the experiments are
important.

The suggested QC approach will consist of:

* _ Triplicate samples of both reactor and inhibited
control at each sampling time

* The analysis of surrogate spike compounds in
each sample

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

* The analysis of a matrix spike in approximately
10 percent of the samples.

The analysis of triplicate samples provides for the overall
precision measurements that are necessary to determine
whether the difference is significant at the 80 percent
confidence level. The analysis of the surrogate spike will
determine if the analytical method performance is consis-
tent (relatively accurate). The matrix spike will be used to
measure overall analytical accuracy. The method blank
will show if laboratory contamination has had an effect 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.



Weeks from Project Start

‘Treatability Study Execution 12

Task 4
Data Analysis & Interpretation | 2

Task 5
Report Preparation 12
Task 6 :
Residuals Management 12

TASK Span,
Weeks F772 T=] [5] 2]? [e]® [|] 2] |r] 9] 7]10] 20] 21] 22] ]z foo
Task1 M1 M2
Work Pian Preparation 4
Task 2 M3 Ma
SAP, HSP, & CRP Preparation 6 2 '
Task 3

‘mma = Administrative approval, document review, or sample “meni

M-1 Submit Work Plan Wk2

M-2_ Receive Work Plan Approval Wk4

M-3 Submit SAP, HSP, CRP Wks

M-4 Receive SAP, HSP Approvals Wk 10

M-5 Collect Sample : Wk 12 .

M-6 Receive Sample Characterization Results Wk 16
M-7 Collect Treatability Study Samples Wk 18
M-8 Collect Project Residual Samples Wk 18

M-9 Receive Treatability Study Analytical Results Wk 22
M-10 Receive Project Residual Analytical Results = Wk 22

M-1I Submit Waste Disposal Approval Form Wk 24
M-12 Submit Draft Report Wk 26
M-13 Receive Review Comments Wk 28
M-14 Receive Waste Disposal Approval Wk 28
M-15_ Submit Final Report; Conduct Briefing Wk 30
M-16 Ship Wastes to TSDF Wk 30

Figure 4-1. Example project schedule for a treatability study.

4.8 MANAGEMENT AND STAFFING

The Work Plan should discuss the management and staff-
ing of the remedy screening treatability study and identify
the personnel who will be responsible for executing the
treatability study at this level. Generally, the following

expertise is needed for the successful completion of the
remedy screening treatability study:

* — Project manager (work assignment manager)
¢ Chemist

*  Microbiologist, environmental scientist/engineer,
or bioengineer

* Lab technician

¢ Quality assurance manager.

Responsibility for various aspects of the project is typi-
cally shown in an organizational chart such as the one in
Figure 4-2.

4.9 BUDGET

The Work Plan should discuss the budget for completion
of the remedy screening treatability study. The cost of
biotreatability evaluations varies tremendously. Histori-
cally, the cause of this wide variation has been significant
differences in the scope of work associated with specific
site characteristics. The lack of established standard pro-
cedures, to date, for performing biotreatability evaluations
has led remediation firms to develop their own “standard
procedures.” This guide will serve as an important aid in
accurately defining data that should be produced from a
biotreatability remedy screening evaluation and ensuring
that the data will be sufficient for deciding whether to
proceed to the next phase of development of the
bioremediation process.

The cost of the remedy screening phase is directly related
to the method of sample collection, the number of samples
collected, the type and number of chemical analyses per-
formed on samples, and the number of replicate remedy
screening tests performed. The factor which is most likely
to influence the cost of the remedy screening is the ana-





+ Produce the design information required for the
next level of testing, should the remedy screening
evaluation be successful.

The Aerobic Biological Remedy Screening Study should

not be the only level of treatability study performed before
final remedy selection.

1.3 INTENDED AUDIENCE

This document is intended for use by Remedial Project
Managers (RPMs), Potentially Responsible Parties (PRPs),
consultants, contractors, and technology vendors. Each
has a different role in conducting treatability studies under
CERCLA. Specific responsibilities for each can be found
in the generic guide."

1.4 USE OF THIS GUIDE

This guide is organized into seven sections, which reflect
the basic information required to perform treatability stud-
ies during the RI/FS process. Section 1 provides back-
ground information on the role of treatability studies in the
RFS process, describes the purpose and scope of the
guide, and outlines the intended audience for the guide.
Section 2 describes the different types of aerobic
bioremediation processes currently available and discusses
how to conduct a preliminary screening to determine if
biological treatment is a potentially viable remediation.
technology. Section 3 provides an overview of the differ-
ent levels of treatability testing and discusses how to de-
termine the need for treatability studies. Section 4 provides
an overview of the remedy screening treatability study,
describes the contents of a typical work plan, and dis-

cusses the major issues that need to be considered when
conducting a treatability study. Section 5 discusses the Sam-
pling and Analysis Plan, including the Field Sampling and
Quality Assurance Project Plans. Section 6 explains how to
interpret the data produced from a remedy screening treatabil-
ity study and how to determine if further remedy selection
studies are justified. Section 7 contains the references.

This guide, along with guides being developed for other
technologies; is intended to be used as a companion docu-
ment to the generic guide. In an effort to avoid redun-
dancy, supporting information in other readily available
guidance documents is not repeated in this document.

This document was reviewed by representatives from EPA’s
Office of Emergency and Remedial Response (OERR),
Office of Research and Development (ORD), Office of
Waste Programs Enforcement, Technology Innovation Of-
fice, and Regional offices, as well as by a number of
contractors and academic personnel. The constructive com-
ments received from this peer review process have been
integrated and/or addressed throughout this guide.

" As treatability study experience is gained, EPA antici-

pates further comment and possible future revisions to
the document. For this reason, EPA encourages con-
structive comments from outside sources. Comments
should be directed to:

Mr. David Smith

U.S. Environmental Protection Agency
Office of Research and Development
Risk Reduction Engineering Laboratory
26 W. Martin Luther King Drive
Cincinnati, Ohio 45268

(613) 569-7957



Non-uniform particle size distribution, the type of soil,
and the permeability of the soil to air and water are the soil
characteristics that most affect the aerobic biodegradation
process, especially in situ. Organic contaminants tend to
be adsorbed to fine particles such as silts and clays. There-
fore, non-uniform particle size distribution can cause incon-
sistent degradation rates for in situ processes due to variations
in biological activity associated with variable contaminant
composition and concentrations. The presence of signifi-
cant quantities of decaying organic matter (humus, peat,
etc.) may cause high oxygen uptake rates, depleting avail-
able oxygen supplies in the soil. Materials handling and
mixing in above-ground processes are affected by particle
size distribution and debris present in the soil.

Low soil permeability can hinder the flow of air, moisture,
and nutrients, limiting the effectiveness of in situ pro-
cesses. Moisture, oxygen, and nutrient content in soils
and soil pH and temperature affect in situ microbial activ-
ity. Generally, such characteristics can be controlled or
modified through engineering practices.

The presence of an active microbial population with the
capability to degrade the contaminants of interest is essen-
tial to the success of in situ processes. The activity and

concentration of soil microbes can be stimulated by mois-
ture, nutrient, and oxygen additions. Selected microor-
ganisms can be added to enhance the natural population.
However, the ability of these organisms to compete in situ
needs to be established on a case-by-case basis. The
addition of microbes and nutrients can be severely limited
by low soil permeabilities. Even in relatively permeable
soils, ion exchange and filtration mechanisms can limit
the effectiveness of microbial and nutrient amendments.

The biodegradability of soil contaminants is affected by
the solubility, volatility, and partition coefficients of the
pure compounds. Interactions with the soil and other
contaminants may affect these chemical characteristics.
Aging of soil contaminants can lead to binding in soil
pores, which can limit the availability, even of soluble
compounds. Variable waste composition and concentra-
tion will affect the efficiency of aerobic biodegradation,
especially in situ. The presence of elevated levels of
heavy metals, pesticides, highly chlorinated organics, and
some inorganic salts can inhibit microbial activity.

The importance of these factors in deciding whether to
initiate or continue treatability studies can be illustrated by
the following example.

Example 2.

A remedy screening test shows that a contaminant is aerobically biodegradable.
However, soil sampling indicates the contaminant is located more than 25 feet deep in
asoil of very low permeability. In situ biodegradation is probably not feasible due to the
thickness of the low permeability soil layer and the depth of the contaminant. In this
case, it may not be worth spending the funds to perform remedy selection treatability
studies for in situ biological treatment processes.

12





FOREWORD

Today’s rapidly developing and changing technologies and industrial
products and practices net carry with them the increased gen-
eration of materials that, if improperly dealt with, can threaten both
public health and the environment. The U.S. Environmental Protec-
tion Agency (EPA) is charged by Congress with protecting the
Nation’s land, air, and water resources. Under a mandate of national
environmental 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
Jaws direct the EPA to perform research to define our environmental
problems, measure the impacts, and search for solutions.

The Risk Reduction Engineering Laboratory (RREL) is responsible
for planning, implementing, and managing research, development,
and demonstration programs to provide an authoritative, defensible
engineering basis in support of the policies, programs, and regula-
tions of the EPA with respect to drinking water, wastewater, pesti-
cides,. toxic substances, solid and hazardous wastes, and
Superfund-related activities. This publication is one of the products
of that research and provides a vital communication link between the
researcher and the user community.

The primary purpose of this guide is to provide standard guidance for
designing and implementing an aerobic biodegradation remedy screen-
ing treatability study in support|of remedy evaluation. Additionally,
it describes a three-tiered approach, that consists of 1) remedy screen-
ing, 2) remedy selection, and 3)|remedy design, to aerobic biodegra-
dation treatability testing. It also presents a guide for conducting
treatability studies in a systematic and stepwise fashion for determi-
nation of the effectiveness of aerobic biodegradation in remediating a
CERCLA site. The intended audience for this guide comprises Re-
medial Project Managers (RPMs), Potentially Responsible Parties
(PRPs), contractors, and technology vendors.

| E. Timothy Oppelt, Director
Risk Reduction Engineering Laboratory

iti



4.4 SAMPLING AND ANALYSIS

The Work Plan should describe the sampling pro:

to be used during field sampling and remedy screenin;
treatability studies. Appropriate methods for preserving!
samples and specified holding times for those samples’
should be used, The procedures wil be site-specific. Stan-|
dard EPA and American Society for Testing and Materials!
(ASTM) methods are generally recommended; however,
the treatability study vendor may propose modified or
equivalent methods that are more suited to the specific]
treatment process being studied. The EPA RPM must!
determine the acceptability of these alternative methods|
with respect to the test objectives and the available method
validation information provided by the vendor. The Work|
Plan also should note that the Sampling and Analysis Plan|
(SAP) will be prepared before field sampling and treat-
ability testing begins. Section 5 provides details for the;
preparation of the SAP including the Field Sampling Plan|
(SP) and the Quality Assurance Project Plan (QAP)P).

4.4.1 Field Sampling

A sampling plan should be developed that directs the
collection of representative samples from the site for the}
treatability test. The sampling plan should be site-specific
and describe the number, location, and volume of samples;
to be collected. Typically, little information is available at)
this point of the RI; therefore, good engineering judgment
must be used. An adequate volume of soil sample should
be collected from each sampling location to account for’
replicate treatability tests and analytical quality assurance/'
quality control (QA/QC) requirements.

Depending upon the goals of the remedy screening treat-
ability study, samples representative of conditions typi-
cal of the entire site or defined areas (i.e., hot spots)
within the site should be collected. The selection of soil
sampling locations should be based on knowledge of the’
site. Information from previous soil samples, soil gas
analysis using field instrumentation, and obvious odors
or residues are examples of information that can be used
to specify sample locations.

The method of sample collection is site-specific. For
example, drill rigs or hand augers can be used to collect
samples, depending on the depth of the sample required
and the soil characteristics. If the target contaminants are
volatile, care should be taken to minimize their loss when
they are composited. Compositing is usually appropriate
for soils containing non-volatile constituents; however,
compositing samples on ice is a good method of minimiz-
ing the loss of volatile compounds.

4.4.2 Sampling During the Remedy
Screening Treatability Study

During the remedy screening treatability study, the extent
of biodegradation is assessed by removing samples from a
large test reactor, or sacrificing the entire contents of smaller
test systems, at predetermined time intervals. The concen-
trations of contaminants, at a minimum, should be deter-
mined at the beginning, at some intermediate time point,
and at the end of the experiment. Therefore, a minimum.
of three sampling points is normally required. A useful
approach is to establish enough test systems so that the
remedy screening study can be extended or additional
samples can be removed and archived for analysis, if re-
quired. The length of the study will be determined by the
biodegradability of the contaminants. For example, treat-
ability tests for BTEX wastes may be conducted within 3
to4 weeks. Tests involving PAHs may take several months
because microorganisms will likely attack the structurally
less complicated molecules before more complex mol-
ecules. As discussed earlier, measures of microbial activ-
ity may be useful in identifying appropriate sampling times.

4.4.3 Analysis

The concentrations of some important matrix parameters
are determined by using standard analytical chemistry meth-
ods (Table 4-2). These parameters should be determined
before the treatability study begins. These parameters are
important for the design of remedy selection and remedy
design studies; they should not be used as an indication of
the inappropriateness of the technology.

Table 4-2. Commonly Used Analytical Chemistry
Methods for Soil Parameters

Methods
Analysis Liquid/Studge Soil
Moisture 160.3" ASTM 2216")
Nitrate 92004/300.0%5) _
Total Organic Carbon 9060°4/415,1) 9060
Total Kjeldahl Nitrogen 351.209) ASTM E778
Soluble Orthophosphate 365.19) _
Soluble Ammonia 350.109) _
pH 90404/150.109 9045)

23



+ Removal Sites Technologies Data

* Resource Conservation and Recovery Act
(RCRA) Delisting Actions

* USATHAMA Installation Restoration and
Hazardous Waste Control Technologies

* — Records of Decision (from 1988 on)
+ Treatability Studies

* Superfund Treatability Data Base (also available
through ATTIC).

In addition, the ATTIC system contains a number of resi-
dent data bases that have been previously developed, as,
well as access to on-line commercial data bases. For more|
information, contact the ATTIC System Operator at (301)
816-9153.

The Office of Solid Waste and Emergency Response!
(OSWER) maintains an Electronic Bulletin Board System|
(BBS) as a tool for communicating ideas and disseminat-
ing information and as a gateway for other Office of Solid|
Waste (OSW) electronic data bases. Currently, the BBS
has eight different components, including news and mail
services and conferences and publications on specific tech-
nical areas. The contact is James Cummings at (202) 382-
4686.

The RREL in Edison, New Jersey, contains a Computer-|
ized On-Line Information System (COLIS), which con-|
solidates several computerized data bases by RREL in|
Cincinnati and Edison. COLIS contains three files: Case
Histories, Library Search, and SITE Applications Analy-
ses Reports (AARs). The Case Histories file contains’
historical information obtained from corrective actions
implemented at Superfund sites. The Library Search sys-
tem provides access to special collections and research,
information on many RREL programs. The SITE AARs
file provides actual cost and performance information.
The contact is Pacita Tibay at (201) 906-6871.

2.2.2 Technical Assistance

The Technical Support Project (TSP) is made up of six
Technical Support Centers and two Technical Support
Forums. It is a joint service of OSWER, ORD, and the
Regions. The TSP offers direct site-specific technical
assistance to On-Scene Coordinators (OSCs) and RPMs
and develops technology workshops, issue papers, and
other information for Regional staff. The TSP: |

* Reviews contractor work plans, evaluates
remedial alternatives, reviews RI/FS, assists in
selection and design of final remedy

* Offers modeling assistance and data analysis and
interpretation

* Assists in developing and evaluating sampling
plans

* Conducts field studies (soil gas, hydrogeology,
site characterization)

* Develops technical workshops and training, issues
papers on groundwater topics, and generic
protocols

* Assists in performance of treatability studies.

The following support centers provide technical informa-
tion and advice related to aerobic biodegradation and treat-
ability studies:

1. Ground-Water Fate and Transport Technical
Support Center
Robert S. Kerr Environmental Research Laboratory
(RSKERL), Ada, OK
Contact: Don Draper
FTS 743-2202 or (405) 332-8800

RSKERL in Ada, Oklahoma, is EPA’s center for
fate and transport research, focusing its efforts on
transport and fate of contaminants in the vadose and
saturated zones of the subsurface, methodologies
relevant to protection and restoration of groundwa-
ter quality, and evaluation of subsurface processes
for the treatment of hazardous waste. The Center
provides technical assistance such as evaluating re-
medial alternatives; reviewing RI/FS and RD/RA
work plans; and providing technical information and
advice.

2. Engineering Technical Support Center

Risk Reduction Engineering Laboratory (RREL),
Cincinnati, OH
Contact: Ben Blaney

* FTS 648-7406 or (513) 569-7406

The Engineering Technical Support Center (ETSC) is
sponsored by OSWER but operated by RREL. The
Center handles site-specific remediation engineering
problems. Access to this support Center must be
obtained through the EPA remedial project manager.



i igati Record of Remedial Design/
Remedial Investigation/
Feasibility Study (QUES) Decision —<— Remedial Action —m.
| |
Identification Remedy
of Alternatives Selection

Scoping Site i i

=e | Sac | et, = | = an
RIFS Screening

| |

Literature REMEDY

Screening | SCREENING

Treatabili to Determine

study Scoping] Technology Feasibility
1 REMEDY SELECTION
to Develop Performance
and|Cost Data
| | REMEDY DESIGN
| to Develop Scale-Up, Design,

| and Detailed Cost Data

Figure 3-2. The role of treatability studies in the RI/FS and RD/RA process.

has the potential to work. Rather, it may go directly to
remedy selection to verify that performance standards can
be met. Figure 3-2 shows the relationship of three level:
of treatability study to each other and to the RI/FS process;

3.2 APPLICATION OF TREATABILITY
TESTS

Before conducting treatability studies, the objectives of
each tier of testing must be established. Aerobic biodegra-
dation treatability study objectives must be based upon the
specific needs of the RI/FS. There are nine evaluation
criteria specified in the EPA’s RI/FS Interim Final Guid+
ance Document (OSWER-9335:3-01); the treatability stud!
ies can provide data upon which up to seven of these
criteria can be evaluated. These seven criteria are:

* Overall protection of human health and environment)

* Compliance with applicable or relevant and
appropriate requirements (ARARs)

+ Reduction of toxicity, mobility, or volume through
treatment

* Short-term effectiveness

* Implementability

+ Long-term effectiveness and permanence
* Cost.

The first four of these evaluation criteria deal directly or
indirectly with the degree of contaminant reduction
achievable by the aerobic biodegradation process. How
“clean” will the treated soil be? Will the residual con-
taminant levels be sufficiently low to meet the risk-
based contaminant levels established to ensure that the
treatment technology achieves and maintains protection
of human health and the environment? What are the
contaminant concentrations and physical and chemical
differences between the untreated and the treated soil
(e.g., has contaminant toxicity, mobility, and volume
been reduced through treatment?)? The fourth criterion,
short-term effectiveness, addresses the effects of the treat-
ment technology during the construction and implemen-

15


(biodegradation) during the study period,

under appropriate conditions, naturally
large percentage of the solvent.

The second study was a remedy design
after 5 months the solvent could not be bi

|
| Even though above-ground slurry-phase

treatment is not appropriate for the site of concern, the previous study did show that,

curring microorganisms can biodegrade a

(pilot-scale) demonstration that showed that
jodegraded in situ, even with the addition of

nutrients and oxygen. This study indicates that in situ biodegradation of the solvent is

not likely to occur.

At first glance, the literature review appeat to rule out the use of in situ bioremediation
to clean up the solvent-contaminated subsurface soil. However, caution should be
used in excluding aerobic biodegradation|on the basis of one study. The intent of the
remedy screening treatability study is to, assess the potential of a technology at a
minimum cost. Ifthere is any reasonto believe aerobic biodegradation has the potential
toremediate the contaminantofinterest, ine studies should be considered.

The first study indicated that biodegradation is potentially a viable technology. How-
ever, successful biodegradation in a slurry bioreactor is not an assurance that in situ
biodegradation will occur. The second study tends to indicate thatin situ bioremediation

of this contaminant will not be possible.

this case, the RPM decided that a quick’
assess the feasibility of using biological tr

lowever, a simple change in pH or nutrient

composition, the removal of some inhitery substance, or the use of a different
microbial population could result in successful in situ bioremediation of the solvent. In

remedy screening study was warranted to
reatment at the site of concern.

Examples of classes of compounds that are readily ame-
nable to bioremediation are petroleum hydrocarbons such
as gasoline and diesel fuel; wood-treating wastes such as
creosote and pentachlorophenol; solvents such as acetone,
ketones, and alcohols; and aromatic compounds such as
benzene, toluene, xylenes, and phenols. Several documents
and review articles that present detailed information on
the biodegradability of compounds are listed in the refer-
ence section.®¢0022023 However, discretion should
be exercised when using these reference materials, as mi-
croorganisms that can biodegrade compounds tradition-
ally considered non-biodegradable are continually being
discovered through ongoing research and development
efforts.

2.2.4 Technology Limitations

Many factors impact the feasibility of aerobic biodegra-
dation in addition to the inherent biodegradability as
measured in the screening test. These factors should be
addressed prior to the selection of aerobic biodegrada-
tion and prior to the investment of time and funds in
further testing. Some of these factors are discussed in
this section. A detailed discussion is beyond the scope

of this document. The reader should consult references
15 through 18, and others, for more information on these
factors.

The concentrations of contaminants and pH are examples
of parameters that influence the feasibility of using bio-
logical treatment processes. However, it should be noted
that treatment systems can be designed and engineered to
accommodate wastes with high contaminant concentra-
tions and extreme pH values. For example, diesel-con-
taminated soil with a pH of 2 can be treated biologically.
However, a neutralization step is required to adjust the pH
to within a range conducive to biological treatment (gen-
erally 6.5 to 8.5) prior to bioremediation. Likewise, if the
concentrations of contaminants are high enough to inhibit
microbiological activity, a dilution step can be introduced
to reduce the concentrations to within ranges conducive to
biological treatment. For example, solid-phase treatment
systems are generally operated at a maximum of 5 to 10
percent extractable oil and grease. These concentrations
of oil and grease can be achieved by mixing less contami-
nated soil with heavily oiled soils in above-ground pro-
cesses. Metals may be leached or complexed to reduce
microbial toxicity and improve the potential for contami-
nant treatment.



Contaminant concentrations should be determined at the
beginning of the study and at the sample times chosen in
the experimental design. Consult U.S. EPA SW-846TM
for the appropriate methods. When determining volatile
and semi-volatile organics, GC or other appropriate meth-
ods (e.g., HPLC) should be used whenever possible, rather
than gas chromatography/mass spectrometry (GC/MS)
methods, to minimize costs. All sampling and analysis
should be performed in accordance with the SAP
(Section 5).

4.5 DATA ANALYSIS AND
INTERPRETATION

‘The Work Plan should discuss the techniques to be used in
analyzing and interpreting the data. The following data
should be reported for each treatability test:

* Concentration of chemicals in samples at the time
of sampling (field concentration) and before the
samples are added to the reactors (T, reactor

concentration)

Amount of soil used in the reactors and a descrip-
tion of all modifications to the reactors

Quantity of residual chemical(s) in each of the
reactors at each sampling time

Quantity of chemical(s) lost due to abiotic
processes

‘Temperature profile over the entire experiment
recorded in a written log indicating type, extent,
and time of any action

Any other additions, removals, changes, manipu-
lations, or mishaps that occur during the course of
the experiment should be recorded in a written log
indicating type, extent, and time of any action

¢ All cited analytical and microbiological proce-
dures (recorded in a written log)

All quality control data (e.g., recovery percentage
of spikes; contaminant concentrations, if any, in
experimental and analytical blanks).

Additional information on the interpretation of treatability
study data is presented in Section 6 of this document.

24

4.6 REPORTS

The Work Plan should discuss the organization and con-
tent of interim and final reports. Once the data have been
gathered, analyzed, and interpreted, they must be incorpo-
rated into a report. A suggested organization for the treat-
ability study report is provided in Subsection 4.12 of the
generic guide.

If the report indicates aerobic biodegradation has potential
(see Section 6 for guidance on interpretation of treatability
data), the project can progress to the next level. In gen-
eral, if the average reduction in contaminant concentration
attributable to biodegradation exceeds 20 percent during a
6- to 8-week test period, the remedy screening is consid-
ered positive. Additional studies will be required before
selecting a remedy in the ROD.

4.7 SCHEDULE

The Work Plan should discuss the schedule for complet-
ing the remedy screening treatability study. When prepar-
ing a schedule for conducting treatability studies, it is
advantageous to break down the entire process into dis-
tinct tasks that are common to most studies.

Listed below are specific tasks that should always be con-
sidered when scheduling:

Work Plan preparation

SAP preparation

Sample collection and disposal

Field sample analysis
Treatability test (including analyses)
Data validation

Report preparation.

The tasks that have the greatest potential for time variance
are usually the Work Plan preparation and the treatability
tests. The treatability test schedule is unpredictable with-
out a firm understanding of the contaminant types and
concentrations involved. For example, remedy screening
treatability tests for BTEX wastes may be conducted within
a couple of weeks; tests involving PAHs may take several
months for the reasons discussed in Subsection 4.4.2.

.

The schedule itself is usually most helpful if displayed in
the form of a bar chart, such as the one shown in Figure 4-1.


Excavation

Water Recycle

ia

Soil Screening

Nutrients
Aeration
Microorganisms

Wt

Dewatered
Solids

L

LL

C J

Dewatering

Slurry Bioreactors

Figure 2-3. Above-ground slurry-phase bioremediation.

Nutrients
Aeration
Microorganisms

Mixer

wy
impermeable
Liner

Figure 2-4. Slurry-phase bioremediation in existing lagoon.

irrigation techniques are generally used to maintain mois-
ture content, pH and nutrient concentrations within ranges
conducive to the biodegradation of contaminants. The
system can be designed to control the release of volatile
organic compounds by passing the exhaust from the
vacuum through activated carbon (Figure 2-5).

2.1.5 Composting

Composting involves the storage of biodegradable waste
with a bulking agent (e.g., chopped hay or wood chips).
‘The structurally firm bulking agent can be biodegradable,
but need not be so. Typically, two parts bulking agent are
mixed with one part contaminated soil to improve the soil
permeability. Adequate aeration, optimum temperature,



ACKNOWLEDGMENTS

This guide was prepared for the U.S. Environmental Protection Agency,
Office of Research and Development (ORD), Risk Reduction Engi-
neering Laboratory (RREL), Cincinnati, Ohio, by Science Applications
International Corporation (SAIC) along with its subcontractor,
Environmental Resource Management, Inc. (ERM), under Contract No.
68-C8-0061. Mr. David Smith served as the EPA Technical Project
Monitor. Jim Rawe served as the primary technical author and SAIC’s
Work Assignment Manager. Mr. Derek Ross served as a technical
expert and was ERM’s Subcontractor Manager. The project team
included Tom Wagner, George Wahl, and Joe Tillman of SAIC; Jonathan
Moyer of ERM; and Mike Martinson of Delta Environmental Consult-
ants, Inc. Clyde Dial served as SAIC’s Senior Reviewer, and Natalie
Bames served as the Technical Editor. The authors are especially
grateful to Mr. Steve Safferman of EPA, RREL, who has contributed
significantly by serving as a technical consultant during the develop-
ment of this document.

Ms. Robin M. Anderson of the Office of Emergency and Remedial
Response (OERR) has been the inspiration and motivation for the
development of this document. The authors want to give special thanks
to Fran Kremer, EPA, CERI; Joe Healy, EPA, Region IX; Peter
Chapman, EPA, ORD; Carol Litchfield, Environment American, Inc.;
Dick Woodward, ENSR, Inc; Paul Flathman, O.H. Materials Corpora-
tion; John R. Smith, ReTeC, Inc.; and Ronald Crawford, University of
Idaho, for their continued involvement in the development of this
document.

The following other Agency and contractor personnel have contributed
their time and comments by participating in the expert workshop and/or
peer reviewing the draft document:

Ron Lewis EPA, RREL

John Glaser EPA, RREL

Rich Haugland EPA, RREL

Henry Tabak EPA, RREL

Ben Blaney EPA, RREL

Ed Bates EPA, RREL

Pat McDonald EPA, Region VII

Chris Rascher EPA, Region I

Linda Fiedler EPA, Technical Information Officer
John Rodgers EPA, ERL - Athens

Maureen Danna ABB Environmental

Kate Devine Applied Biotreatment Association
Dick Bleam Bioscience Management

Durell Dobbins Biotrol

Tom Chresand Biotrol

viii



plete mixing of sterilization agents with soils can result i
pockets of surviving microbes in soil pores. In some >
microbial populations can transform and detoxify steriliz-
ing agents. Complete sterilization of the control is not
necessary provided that biological activity is inhibited suf-
ficiently so that a statistically significant difference be!
tween the test and control means can be determined.
However, care should be taken in interpreting remedy
screening study results. Substantial degradation in the
control (¢.g., 20-50 percent contaminant reduction, or more}
can mask the occurrence of biodegradation in the test
reactor. If the control reactor has the same or greate!
percent degradation as the test reactor, a false negative
conclusion can result. Concluding that no biodegradatior
occurred, when in fact there was some biodegradation,
can lead to elimination of this technology unnecessarily,
Alternatively, closed test systems with volatile traps c:
be used to monitor the volatilization of compounds inste:
of using inhibited controls to estimate abiotic losses.“ |
A Statistical experimental design should be used to con:
duct the treatability study in order to support decision:
made from the treatability data. The various parameters
of interest are included as factors in the experimental de-
sign. The treatability experiment should include monitor.
ing the concentration of chemicals of interest over time:
In general, at least three to four time periods should be
studied, including the time-zero (T,) analysis. However,
if the study goals are met after a sampling period, then it is
not necessary to continue sampling at additional time peri-
ods. (For example, if 70-percent reduction was achieved
after 1 week, it would not be necessary to continue testing
if the goal was to achieve only a 20-percent reduction.)

The test system can consist of a single large reactor of
multiple small reactors. In the case of the single reactor,
small subsamples are removed at various times and com!
pared to subsamples from a second reactor in which bio}
logical activity has been inhibited. Normally, triplic:

subsamples are taken at each time point. The mean con-|
taminant concentrations in the test and control reactors are}
compared to see if a statistically significant change in|
concentration has occurred. The mean contaminant con-|
centration in the inhibited control subsample can be sub-|
tracted from that in the test subsample to estimate the!
percentage the contaminant has biodegraded at each time|
point. In this type of system, heterogeneity within the soil|
system can lead to variability in contaminant concentra-
tion among the various subsamples and replicates. How-
ever, such system variability can be overcome by thorough|
mixing of the soil before it is distributed to the test and|
control systems. Examples of this type of system are large’
flasks, soil pans, and other large soil reactors. Care should|
be taken so that the system size and design do not limit the

21

availability of oxygen and moisture and cause variability
in degradation rates within the reactor.

Multiple reactors may be set up in place of a large soil
system. Triplicate reactors are established for each test
reactor and control group at each time point. Each reactor
is filled with the same amount of soil and nutrient addi-
tives. In this case, the complete reactor contents are ex-
tracted and analyzed for each of the triplicate test and control
reactors at each time point. Examples of such systems are
serum bottles, slurry reactors, and aerated soil reactors.
The advantage of this type of experimental apparatus is that
the question of subsampling representativeness is avoided.
However, the representativeness of any one reactor is ques-
tionable in this design. Thorough mixing of the soil, before
it is distributed among the individual reactors, is important.

Triplicate samples provide a measure of the overall preci-
sion of the measurements made. Surrogate spikes should
also be added to the matrix samples to ensure consistent
analytical performance. Matrix spikes should be added to
a percentage (approximately 10%) of the samples to deter-
mine overall analytical accuracy. Method blanks should
be used to monitor potential contamination of samples
during laboratory handling.

Respirometric measurements or other measures of bio-
logical activity can be used to predict the best times to take
samples. At the beginning of the experiment, activity
measurements should indicate minimal biological activity.
Continued monitoring can reveal either a rapid or rela-
tively slow onset of biological activity and indicate when
samples should be taken to monitor contaminant reduc-
tions. However, respirometric measurements can indicate
the loss of oxygen through chemical oxidation in addition
to biodegradation.)

In formulating an experimental design, the total number of
samples taken depends on the desired difference in con-
centrations that the experimenter wishes to detect, the mea-
surement variability (the analytical coefficient of variation),
and the type I and type II error probabilities. Each of these
factors is discussed below.

The goal of the remedy screening scale of treatability
testing is not to be able to ascertain whether the biotreatment
process can meet cleanup goals but rather whether biodeg-
radation is possible with the site-specific waste material in
question. Therefore, at the remedy screening scale, it is
usually not necessary to establish complete removal of the
contaminant of interest. As a guide, the experiment should
be designed so that a difference of 20 to 50 percent re-
moval of the contaminant of interest can be detected be-
tween the treatment and the inhibited control.





|
TABLE OF CONTENTS

! 1.1 Background
H 1.2 Purpose and Scope. .
i ’ 13 Intended Audience.................00005

1.4 Use of This Guide .................0006-

2. Technology Description and Preliminary Screening . .
2.1 Technology Description. .
Hl 2.2 Preliminary Screening and Technology Limitat

3. The Use of Treatability Studies in Remedy Evaluation .
H 3.1 Process of Treatability Testing in Evaluating a)
' 3.2 Application of Treatability Tests...........

4, Remedy Screening Treatability Study Work Plan... .|..

i 4.1 Test Goals ...
4.2 Experimental Design

4.3 Equipment and Materials .

44 Sampling and Analysis ..

4.5 Data Analysis and Interpretation

4.6 Reports.

4.7 Schedule. .

4.8 Management and Staffing ..

i 49 Budget...

BRRRRBRE

5. Sampling and Analysis Plan .
5.1 Field Sampling Plan. .
5.2 Quality Assurance Project Plan

' 6.  Treatability Data Interpretation ..................

‘ 7. References ..



ABSTRACT

Systematically conducted, well-documented treatability studies are an
important component of the remedial investigation/feasibility study (RV
FS) process and the remedial design/remedial action (RD/RA) process
under the Comprehensive Environmental Response, Compensation, and
Liability Act (CERCLA). These studies provide valuable site-specific
data necessary to aid in the selection and implementation of the rem-
edy. This manual focuses on aerobic biodegradation remedy screening
treatability studies conducted in support of remedy evaluation that is
conducted prior to the Record of Decision (ROD).

This manual presents a standard guide for designing and implementing
an aerobic biodegradation remedy screening treatability study. The
manual presents a description of and discusses the applicability and
limitations of aerobic biodegradation technologies and defines the
prescreening and field measurement data needed to determine if treat-
ability testing is required. It also presents an overview of the process of
conducting treatability tests and the applicability of tiered treatability
testing for evaluating aerobic biodegradation technologies. The spe-
cific goals for each tier of testing are defined and performance levels
are presented that should be met at the remedy screening level before
additional tests are conducted at the next tier. The elements of a
treatability study work plan are also defined with detailed discussions
on the design and execution of the remedy screening treatability study.

The manual is not intended to serve as a substitute for communication
with the experts and/or regulators nor as the sole basis for the selection
of aerobic biodegradation as a particular remediation technology. In
addition, this manual is designed to be used in conjunction with the
Guide for Conducting Treatability Studies Under CERCLA, Interim
Final.“® The intended audience for this guide consists of Remedial
Project Managers (RPMs), Potentially Responsible Parties (PRPs),
contractors, and technology vendors.



Visqueen Cover

Nutrients
Aeration

Microorganisms

Plastic Piping
(compatible with contaminants)

Figure 2-5. Soil

moisture and nutrient contents, and the presence of a
appropriate microbial population are necessary to enhance
the decomposition of organic compounds. The biodegra-

dation process may be thermophilic. If so, microorgan:
isms that occur naturally in the decaying organic mat

biodegrade the contaminants of concern. However, the
elevated temperatures associated with thermophilic bio-

heap bioremediation.

degradation may limit the activity of indigenous and exog-
enous organisms.

The three basic types of composting are open windrow
systems, static windrow systems, and in-vessel (reactor)
systems. In the open windrow system, the compost is
stacked into elongated piles (Figure 2-6). Aeration is

Figure 2-6. Open|windrow composting.



|
TABLES

|

|

|

Number Page
4-1. Suggested Organization of Aerobic Biodegradation|Remedy Screening Treatability Study Work Plan .... . 19
4-2, Commonly Used Analytical Chemistry Methods for Soil Parameters ............ 2 a 23

4-3. Major Cost Elements Associated With Aerobic Biological Remedy Screening Treatability Studies ...

5-1. Suggested Organization of the Sampling and Analysis Plan. eee eee tee cee tee cnet eee e ee 28
6-1. Hydrocarbon Concentration (ppm) Versus Time . | Lessee ce cnc senses eeeer cess eesneeeereeneereee 31



SEC

TION 3

THE USE OF TREATABILITY STUDIES
EVALUATION

IN REMEDY

This section presents an overview of the use of treatability,
tests in confirming the selection of aerobic biodegradation|
as the technology remedy under CERCLA. It also pro-
vides a decision tree (Figure 3-1) that defines the tiered|
approach to the overall treatability study program with,
examples of the application of treatability studies to the!
RI/FS and remedy evaluation process. Subsection 3.1
presents an overview of the general process of conducting,
treatability tests. Subsection 3.2 defines the tiered ap-
proach to conducting treatability studies and the applica-
bility of each tier of testing, based on the information!
obtained, to assess, evaluate, and confirm aerobic biodeg-
radation technology as the selected remedy.

3.1 PROCESS OF TREATABILITY TEST-
ING IN EVALUATING A REMEDY

Treatability studies should be performed in a systematic!
fashion to ensure that the data generated can support the
remedy evaluation process. This section describes a gen-|
eral approach that should be followed by RPMs, PRPs,
and contractors for all three tiers of treatability studies.
This approach includes:

+ — Establishing data quality objectives

* — Selecting a contracting mechanism

¢ — Issuing a work assignment

* Preparing the work plan

* — Preparing the Sampling and Analysis Plan

* Preparing the Health and Safety Plan

* — Conducting community relations requirements

* Complying with regulatory requirements

* Executing the study
+ Analyzing and interpreting the data
+ — Reporting the results.

These elements are described in detail in the generic
guide." The generic guide presents general informa-
tion applicable to all treatability studies first, followed
by information specific to each of the levels of treatabil-
ity testing.

Treatability studies for a particular site will often entail
multiple tiers of testing. Duplication of effort can be
avoided by recognition of this possibility in the early plan-
ning phases of the project. The work assignment, work
plan, and other supporting documents should include ail’
anticipated activities to ensure continuity in the project as
it moves from one tier to another.

* There are three levels or tiers of treatability studies: rem-

13

edy 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 (¢.g., selection of an inappro-
priate treatment alternative). These decisions are based on
the quantity and quality of data available and on other
decision factors (e.g., State and community acceptance of
the remedy, new site data). The flow diagram in Figure 3-
1 shows the decision points and factors to be considered in
following the tiered approach to treatability studies.

Technologies generally are evaluated first at the remedy
screening level and progress through the remedy selection
to the remedy design level. A technology may enter,
however, at whatever level is appropriate based on avail-
able data on the technology and site-specific factors. For
example, a technology that has been studied extensively
may not warrant remedy screening to determine whether it



SEPA

United States Office of Research and EPA/540/2-91/013A

Environmental Protection | Development July 1991
Agency Washington, DC 20460

Superfund

Guide for Conducting
Treatability Studies Under
CERCLA: Aerobic
Biodegradation

Remedy Screening

Interim Guidance



23. U.S. Environmental Protection Agency. Technology

Screening Guide for Treatment of CERCLA Soils
and Sludges. EPA/540/2-88/004, 1988.

. U.S. Environmental Protection Agency. Test Methods
for Evaluating Solid Waste. 3rd Ed., SW846, 1986.

. U.S, Environmental Protection Agency. Test Method:
The Determination of Inorganic Anions in Water by
Ton Chromatography — Method 300.0.
EPA-600/4-84/017, 1984.

36

26.

27.

U.S. Environmental Protection Agency. Treatability
Studies Under CERCLA: An Overview. Office of
Solid Waste and Emergency Response, Directive
9380.3-02FS, 1989.

40 CFR, Section 796.3400.

“U.S. Government Printing Office: 1991 — 548-187/40553





Keith Piontek
Tom Simpkin
Robert Finn
William Mahaffey
Ralph Baker
Barry Scott
John Cookson
Al Rozich

Gary Boettcher
Suxuan Huang
Ralph Portier
Anthony Bulich
Todd Stevens
Ralph Guttman
Phillip Launt
Hans Stroo
David Nutini
Rick Bartha
Larry N. Britton
Robert Irvine
James Early
Jim Spain

John A. Dickerson
Daniel Shelton
Brian Schepart

CH2M Hill
Comell University
Ecova Corporation

st Inc.

ISR, Inc.
General Physics Corporation
ERM
Geraghty & Miller, Inc.
Keystone Environmental Resources
Louist State University
Microbics
Pacific Northwest Laboratories
Polyl , Corporation
Resource Appraisals & Management
ReTeC, Inc.
RNK Environmental, Inc.
Rutgers University
Texas Research Institute, Inc.
University of Notre Dame
University of Notre Dame
US. Air Force
USDA
USDA
Wastestream Technology

|

The document was also reviewed by the Office of Waste Programs
Enforcement and the Technology Innovation Office. We sincerely
hope we have not overlooked anyone who participated in the develop-
ment of this guide.



The average contaminant concentration of the bioreactor, at each time point, is
corrected by the average contaminant concentration of the inhibited control, at the
same time point, to measure the biodegradation at that time point. The inhibited con-
trol accounts for contaminant losses due to volatilization, adsorption to soil particles,
and chemical reactions. Some contaminant loss in the control due to biodegradation
may occur since total sterilization is difficult to accomplish. However, if a statistically
significant difference between the test and control means exists, then biodegradation
has occurred in the test bioreactor. The difference between the two means is tested
using Analysis of Variance (ANOVA) methods at the 80 percent confidence level for
each of the test times. If the difference between the two means is significant at T;, no
further test measurements are required. If the difference between the two means is
not significant at T;, then the remedy screening test continues until some Tz. This
process is repeated until a statistically significant difference between the two means
is found or the treatability study is determined to be unsuccessful and is discontinued.
In this example, a statistically significant difference between the two means occurs at
Tg. The data, therefore, indicate that bioremediation is a viable treatment option and
that further remedy selection studies are appropriate. The 80% confidence interval
about each mean is shown in Figure 6-1 to graphically describe the variation associ-
ated with each mean.

€
a
&
o
°
=
*
<
&
g
=
Oo
Co
i=
8
oO

A. inhibited contro! @ non-inhibited control

Figure 6-1. Plot of hydrocarbon concentration versus time.



the treatability study is performed. Each tier of the treatability
study needs performance goals appropriate to that tier. For
example, to use remedy screening tests to answer the question,
“Does aerobic biodegradation work on this contaminant?,” itis
necessary to define “work” (ie., set the goal of the study). A
pollutant reduction of at least 20 percent during the remedy
screening tests may satisfy the test for validity of the process
and indicate that further testing at the remedy selection level is
appropriate to determine if the technology can meet the antici-
pated performance criteria of the ROD.

4.1.1. Remedy Screening Goals

The main goals of the remedy screening evaluation are to:

* Provide an indication that reductions in contami-
nant concentrations are due to biodegradation and
not abiotic processes such as photodecomposition,
volatilization, and adsorption

Produce the design information required for the
next level of testing, should the screening
evaluation be successful.

Normally, the average contaminant concentration should
be reduced by at least 20 percent during a 6- to 8-week
study, as compared to an inhibited control, to conclude
aerobic biodegradation is a potential treatment technology
for the site under investigation. The 20-percent contami-
nant reduction is arbitrary, but is designed to maximize the
chances of success at the remedy screening tier. The
choice of a 6- to 8-week study is to provide a consistent
endpoint for remedy screening studies. The choice of the
remedy screening treatability study goals (time and con-
taminant reduction) will be site-specific decisions.

Example 4 is provided to demonstrate typical goals of a
remedy screening study and what decision can be made
when these goals are achieved.

4.2 EXPERIMENTAL DESIGN

A number of different approaches can be used to conduct
the remedy screening test. These range from simple shake
flask evaluations to soil pans or soil slurry reactors. The
soil may be either saturated or unsaturated, depending on
the goals of the study. Soil slurries will optimize mixing
and will tend to maximize biological degradation. Such
studies will maximize the chances of success at the rem-
edy screening level. Unsaturated soils will often limit
mixing and result in slower degradation rates. However,
such systems will correlate better with field conditions in
many cases and result in better extrapolation to remedy
selection test systems. The object of this guidance docu-
ment is not to specify a particular remedy screening method
but rather to highlight those critical parameters that should
be evaluated during the laboratory test.

The test should include controls to measure the impact of
non-biological processes such as volatilization, sorption,
and photodecomposition on the concentrations of con-
taminants. Inhibited controls can be established by using
formaldehyde, mercuric chloride, or sodium azide to in-
hibit microbiological activity. However, care should be
exercised when selecting a sterilizing agent. For example,
sodium azide can, under certain circumstances, promote
spontaneous explosive reactions. Mercuric chloride com-
plexes certain petroleum hydrocarbons and results in arti-
ficially low hydrocarbon concentrations. Soil structure
also can be modified by sterilization agents. Complete
sterilization of soils can be difficult to accomplish. Incom-

Example 4

The soil of a former wood-preserving site is contaminated with pentachlorophenol
(PCP) waste. The literature search indicated that PCP has been successfully
biodegraded at other sites. The RPM decided a remedy screening study was needed
to measure the potential for successful biodegradation at this site. A goal of 25 percent
reduction of the PCP concentrations was set. The study period was set at 6 to 8 weeks.
These study goals were established to maximize the chances of success for
biodegradation.

A remedy screening study was performed to determine if bioremediation is a viable
cleanup method for the soil. The average PCP concentration was reduced by 37
percent, over a 6-week period, after correction for the inhibited control. The RPM
decided that further treatability studies were warranted and elected to have a remedy
selection treatability study performed to attempt to optimize degradation.





SECTION 4
REMEDY SCREENING TREATABILITY STUDY
WORK PLAN

Section 4 of this document is written assuming that |a
Remedial Project Manager is requesting treatability stud-
ies through a work assignment/work plan mechanism.
Although the discussion focuses on this mechanism, it
would also apply to situations where other contra
mechanisms are used.

This section focuses on specific elements of the Wor
Plan that require detailed discussion because they relat
to the remedy screening level of aerobic biodegradatio}
treatability studies but are not presented in other sec-
tions of the document. These elements include test goals,
experimental design and procedures, equipment and ma-
terials, reports, schedule, management and staffing, an
budget. These elements are described in Subsection
4.1 through 4.9. Complementing these subsections
Section 5, Sampling and Analysis Plan, which includ
the Quality Assurance Project Plan, and Section 6, Treat-
ability Data Interpretation, that address the samplin|
and analysis and data analysis and interpretation ele

ments of the Work Plan. The Work Plan elements are
listed in Table 4-1.

Carefully planned treatability studies are necessary to en-
sure that the data generated are useful for evaluating the
validity or performance of a technology. The Work Plan,
which is prepared by the contractor when the Work As-
signment 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 subse-
quent tasks. For more information on each of these sec-
tions, refer to the generic guide.“

4.1 TEST GOALS

Setting goals for the treatability study is critical to the ultimate
usefulness of the data generated. Goals must be defined before

Table 4-1. Suggested Organization of Aerobic Biodegradation Remedy
Screening Treatability Study Work Plan

Project Description

Experimental Design anc
Equipment and Material

Data Management

Data Analysis and interpt
Health and Safety

10. Residuals Management
11. Community Relations
12. Reports (see Subsection
13. Schedule (see Subsector

OPMONAAARONS>

Remedial Technology Description

Test Goals (see Subsecti

ion 4.1)
Procedures (see Subsection 4.2)
(see Subsection 4.3)

Sampling and Analysis (see Subsection 4.4)

‘tation (see Subsection 4.5)

4.6)
in 4.7)

14, Management and Staffing (see Subsection 4.8)

15. Budget (see Subsection

4.9)

19



FIGURES

Number Page_
2-1. In Situ Bioremediation of Groundwater .............e eee e cece eee cece e rete teen eeee eee teeeneee 4
2-2. Solid-Phase Bioremediation .

2-3. Above-Ground Slurry-Phase Bioremediation ........ 2... ccc eee e nec ence eee eect eee en en ennenes 6
2-4. Slurry-Phase Bioremediation in Existing Lagoon .......... 0. eee eee cece ener een e nee en eeeen en enees 6
2-5. Soil Heap Bioremediation ........ 6.66: eee eee cece cece eee een ener een eee n een n tenn eee e eee 7
2-6. Open Windrow Composting

3-1. Flow Diagram of the Tiered Approach ........ 0... ccs c ence eee reece ener n ence eee en ener er eeeee 14
3-2. The Role of Treatability Studies in the RI/FS and RD/RA Process .........0.0ecececeeeeeeeneneeeee 15
4-1, Example Project Schedule for a Treatability Study... 26.0.0... cece cece cece eee n ence eee e ec ee eens 25
4-2. Organization Chart. + 26
6-1. Plot of Hydrocarbon Concentration versus Time ........ 6.0 e cece e ener e rece eet e ener ener een ceee 32

vi



RREL offers expertise in contaminant source control
structures; materials handling and decontamination;
treatment of soils, sludges and sediments; and treat-
ment of aqueous and organic liquids. The following
are examples of the technical assistance that can be
obtained through ETSC:

Screening of treatment altematives

Review of the treatability aspects of R/FS

Review of RI/FS treatability study Work Plans
and final reports

Oversight of RI/FS treatability studies
Evaluation of alternative remedies
Assistance with studies of innovative technologies

Assistance in full-scale design and start-up

2.2.3 Prescreening Characteristics

‘The major parameter that influences the feasibility of us-
ing biological processes is the biodegradability of the com-
pounds of concern. Prior to conducting a remedy screening
of bioremediation it is important to confirm that the com-
pounds of concern are indeed amenable to biological
treatment.

As discussed in Subsection 2.2.1, a literature search should
be performed for the compounds or wastes of interest,
including compounds of similar structure. The key ques-
tion to be answered is whether any evidence of aerobic

biodegradation of these compounds or wastes exists. The
literature review should not be limited to a biodegradation
technology that has been chosen for preliminary consider-
ation. Evidence of aerobic biodegradation under condi-
tions not likely to be applicable to a site should not be
eliminated from consideration. Likewise, a literature search
indicating that biodegradation is unlikely should not auto-
matically eliminate aerobic biological technologies from
consideration. On the other hand, previous studies indi-
cating that pure chemicals will be degraded must be viewed
with caution. Chemical interactions or inhibitory effects of
contaminants can alter the biodegradability of chemicals in
complex mixtures frequently found at Superfund sites.

The literature search should also investigate the chemical
and physical properties of the contaminants. The volatil-
ity of the contaminants is one of the most important physi-
cal characteristics. Knowledge of the contaminant volatility
is important in the prescreening step since highly volatile
contaminants may be difficult to degrade, especially in
stirred or highly aerated reactors because they volatilize
before thay can be degraded.

There is no steadfast rule that specifies when to proceed
with remedy screening and when to eliminate aerobic bio-
degradation as a treatment technology based on a prelimi-
nary screening analysis. An analysis of the existing
literature coupled with the site characterization will pro-
vide the information required to make an educated deci-
sion. However, when in doubt, a remedy screening study
is recommended. Several guidance documents are avail-
able to aid in determining the key contaminant and matrix
characteristics which are needed to prescreen various tech-
nologies.“®2) Example 1 is a hypothetical literature
search provided to illustrate some of the complexities of
this analysis.

Example 1.

Asite is contaminated with an organic solvent. The contamination extends to a depth
of 50 feet below the surface. Considering the overall extent of the zone of contamina-
tion, removal of the soil for above-ground treatments not considered as a remediation
technology for the site. However, a review of the literature reveals only two previous
studies on the biodegradation of the solvent of concern.

The first study showed that greater than 95 percent of the semi-volatile solvent could
be removed over a 3-week period with a slurry-phase biological treatment process
utilizing naturally occurring soil microorganisms. The study made no attempt to
measure losses due to volatilization. However, a 12-percent loss of solvent was
measured in a control reactor where biodegradation was inhibited with mercuric
chloride to account for abiotic losses (chemical degradation, sorption and volatiliza-
tion). Therefore, 83 percent of the contaminant was removed by biotic processes

10



SECTION 5 —

SAMPLING AND ANALYSIS PLAN

The SAP consists of two parts — the Field Sampling Plan
(FSP) and the QAPjP. This section identifies the contents
of and aids in the preparation of these plans. 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

the quality of the analytical data generated is known. f
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 jis
usually prepared after the Work Plan is approved.

5.1 FIELD SAMPLING PLAN

The FSP component of the SAP describes the sampling
objectives; the type, location, and number of samples to
collected; the sample numbering system; the necessary
equipment and procedures for collecting the samples; the
sample chain-of-custody procedures; and the required pack-
aging, 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 treat-
ability test objectives. Because the primary objective of
remedy screening studies is to provide a first-cut evalua-
tion of the extent to which specific chemicals are removed
from the soil by biological process, the primary sampling
objectives should include, in general:

+ Acquisition of samples representative of condi-
tions typical of the entire site or defined areas
within the site. Because this is a first-cut evalua:
tion, 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 investigation.

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

From these two primary objectives, more specific objec-
tives should be developed. When developing the more
detailed objectives, the following types of questions should
be considered.

* Will samples be composited to provide more
representative samples for the treatability test, or
will the potential loss of target VOCs prohibit
this sample collection technique?

° — Are there adequate data to determine sampling
locations indicative of the more contaminated
areas of the site?

* — Is sampling of a worst-case scenario warranted to
determine if either indigenous or inoculated
microorganisms are able to break down contami-
nants at their highest known concentrations in the
field.

After the sampling objectives are clearly identified, an
appropriate sampling strategy should be described. Spe-
cific items that should be briefly discussed are:

* Sampling objectives

¢ Calibration procedures

* Sample location selection
¢ Sample collection

* Sampling procedures

+ Sample transportation

* Sampling equipment

« Responsible persons

* Sample media type
Sampling strategy



* Sample location map

* Sample history recording procedures

* Sample preservation methods/holding times

* Sample custody and chain-of-custody procedures
Table 5-1 presents the suggested organization of the SAP.

TABLE 5-1. Suggested Organization of the Sampling
and Analysis Plan

Field Sampling Plan
Site Background
Sampling Objectives
Sample Location and Sampling Frequency
Sample Designation
Sampling Equipment and Procedures
Sample Handling and Analysis

Quality Assurance Project Plan

1. Experimental Design

2. Quality Assurance Objectives

3. Sampling and Analytical Procedures
4. Approach to QA/QC

5.2 QUALITY ASSURANCE PROJECT
PLAN

The QAPjP should be consistent with the overall objec-
tives of the treatability study. At the remedy screening
level, the QAPjP should not be overly detailed.

5.2.1 Experimental Design

Section 1 of the QAPjP must include an experimental
project description that clearly defines the experimental
design, the experimental sequence of events, each type
of critical measurement to be made, each type of matrix
(experimental setup) to be sampled, and each type of
system to be monitored. This section may reference
Section 4 of the Work Plan; however, all details of the
experimental design not finalized in the Work Plan should
be defined in this section.

The following items should be included:
* Number of samples (area) to be studied

* Identification of treatment conditions (variables)
to be studied for each sample

Type of reactors to be used for each sample
Target compounds for each sample

Number of replicates per condition per sampling
event

+ Number and time of each sampling event.

The project description should clearly define and distin-
guish the types of critical measurements or observations
that will be made, as well as any system conditions (e.g.,
process controls or operating parameters) that will need to
be monitored routinely. Critical measurements are those
measurement, data-gathering, or data-generating activities
that directly affect the technical objectives of a project. At
a minimum, the determination of the target compound
(identified above) in the initial soil and treated soil samples
will be critical measurements.

“The purpose of the remedy screening treatability study is

to determine whether biological treatment is potentially
applicable to the site under consideration. An example of
a criterion for this determination is a 20 percent reduction
in concentration of the select target compounds at the 80
percent confidence level. If a 20 percent reduction is
obtained, then additional remedy selection studies would
be indicated to optimize the treatment and determine the
cost-effectiveness in comparison to other technologies.

5.2.2 Quality Assurance Objectives

Section 2 should list the QA objectives for each type of
critical measurement and for each type of sample matrix
defined in Section 1, for each of the six data quality indi-
cators: precision, accuracy, completeness, representative-
ness, comparability, and, where applicable, method
detection limit. See reference 21 for additional informa-
tion on the preparation of a QAPjP.

5.2.3 Sampling and Analytical
Procedures

The procedures ‘used to obtain the field samples for the
remedy screening treatability study are described in the
FSP and need not be repeated in this section, but should be
incorporated by reference.



tation of a remedy until the response objectives have
been met.

The implementability assessment evaluates the technical
and administrative feasibility of alternatives and the avail-
ability of required goods and services. The key to assess-
ing aerobic biodegradation under these criteria is whether
the contaminant is biodegradable under site-specific con-
ditions. Additionally, the assessment evaluates whether
vendors and process equipment are available to perform
the remediation, if adequate space exists to perform treat-
ment operations, and what materials handling problems
might be encountered if soil must be excavated.

Long-term effectiveness assesses how effective treat-
ment technologies are in maintaining protection of hu-
man health and the environment after response objectives
have been met. Basically, the magnitude of any residual
tisk and the adequacy and reliability of controls must be
evaluated. The residual risk factor, as applied to aerobic
biodegradation, assesses the risks remaining from re-
sidual contaminant concentrations at the conclusion of
remedial activities.

The final EPA evaluation criterion that can specifically be
addressed during a treatability study is cost. Aerobic bio-
degradation is basically a process that biologically de-
grades organic compounds to carbon dioxide and water or
to some intermediate degradation product. Remedy de-
sign treatability studies provide data to estimate the fol-
Jowing important cost factors:

¢ The initial design of the full-scale unit

° The estimated capital and operating and mainte-
nance costs
Initial estimate of the time required to achieve
target concentrations.

In some cases, remedy selection treatability studies can
provide preliminary estimates of the same cost factors.

3.2.1. Remedy Screening

Remedy screening is the first level of testing. It is used to
establish the validity of a technology to treat a waste.
‘These studies are generally low cost (¢.g., $10,000-$50,000)
and usually require 1 week to several months to complete.
They yield data that can be used as a preliminary indication
of a technology’s potential to meet performance goals and
can identify operating standards for investigation during
remedy selection testing. They generate little, if any, de-
sign or cost data and should not be used as the sole basis for
selection of a remedy.

Typically, aerobic biological remedy screening studies
are performed in test reactors provided with sufficient
nutrients and oxygen. Generally, these studies are batch
processes. These reactors may be small sacrificial batch
reactors (approximately 40 ml to 1 liter in size) or larger
ecosystems (1 to 10 liters) that are subsampled to monitor
the progress of biodegradation. The reactors may contain
saturated or unsaturated soil or slurries in water. Slurry-
phase treatability tests optimize the availability of nutri-
ents and oxygen and offer the best chance of success for
remedy screening studies. Normally, pH and contami-
nant loading rates are adjusted to increase the chances of
success. The microbial population can be indigenous to
the site, from another acclimated source (i.e., wastewater
treatment sludge or another area on site), selectively cul-
tured, a proprietary mixture provided by a vendor, or any
combination of the above. The bioreactors are set up for
replicate sampling at several time points. The test reac-
tors are compared to inhibited controls at each time point
to determine if aerobic biological degradation occurred.
The inhibited reactors are treated with sterilization agents
in an effort to reduce or eliminate the biological activity
in the control reactors. The mean contaminant concentra-
tion in the inhibited control replicates is compared to the
mean contaminant concentration in the test reactors. The
goal for a successful treatability test is a removal rate,
due to biological processes, that is greater than the ana-
lytical error inherent in the test design. A reduction of
the contaminant concentration over a 3- to 6-week period
of 20 percent (minimum) to 50 or 60 percent (corrected
for non-biological losses) would be typical of a success-
ful treatability study. However, for some contaminants,
slower degradation rates may still indicate favorable re-
sults. More information on experimental design is pro-
vided in Subsection 4.2.

Example 3 illustrates the type of information that might
result from a remedy screening study and the conclusions
that might be drawn from that information.

However, even if the remedy screening tests do not meet
the established goals, the test results should be examined
for the potential cause(s) of failure. If such parameters
can be adjusted or corrected to improve the chances of
success of the remedy screening studies, the RPM or con-
tractor should consider running additional remedy screen-
ing tests.

3.2.2 Remedy Selection
Remedy selection testing is the second level of testing. It

is used to identify the technology’s performance on a
waste-specific basis for an operable unit. These studies



DISCLAIMER

‘The information in this document has been funded wholly or in part by
the U.S. Environmental Protection Agency (EPA) under contract No.
68-C8-0061, Work Assignment No. 2-10, to Science Applications In-
ternational Corporation (SAIC). It has been subjected to the Agency's
peer and administrative reviews, and it has been approved for publica-
tion as an EPA document. Mention of trade names or commercial
products does not constitute endorsement or recommendation for use.



10.

. American Society for Testing and Materials. 1987.

SECT
REFER

Annual Book of ASTM Standards.

Box, G.EP., W.G. Hunter, and J.S, Hunter. Statistics
for Experimenters. Wiley, 1978.

Gibson, D.T. Microbial Degradation of Organic Com-
pounds. Microbiology Series. Marcel Dekker, Inc.,
New York, 1984.

Kukor, JJ., and R. H. Olsen. Diversity of Toluene
Degradation Following Long Term Exposure to BTEX
In Situ. In: Biotechnology and Biodegradation.
Daphne Kanely, A. Chakrabarty, and G. Omenn, eds.
Gulf Publishing Co., Houston, Texas, 1989. pp. 405-
421.

Lentner, M., and T. D, Bishop. Experimental Design
and Analysis. Valley Book Company, Blacksburg,
Virginia, 1986.

Loehr, R.C. Land Treatment as a Waste Manage-
ment Technology: An Overview. Land Treatment:
A Hazardous Waste Management Alternative. R.C.
Loehr, et al., eds. Center for Research in Water Re-
sources, The University of Texas at Austin, 1986. pp.
7-17.

Marinucci, A.C., and R. Bartha. Apparatus for Moni-
toring the Mineralization of Volatile “C-Labeled Com-
pounds. Applied and Environmental Microbiology,
38(5):1020-1022, 1979.

Munnecke, D.M., L.M. Johnson, H.W. Talbot, and S.
Barik. Microbial Metabolism and Enzymology of
Selected Pesticides. In: Biodegradation and Detoxifi-
cation of Environmental Pollutants. A.M.
Chakrabarty, ed. CRC Press, Boca Raton, Florida,
1982.

Odeh, R.E. and M. Fox. Sample Size Choice. Marcel
Dekker, Inc., New York, 1975.

Pramer, D., and R. Bartha. Preparation and Process-
ing of Soil Samples for Biodegradation Studies. En-
vironmental Letters, 2(4):217-224, 1972.

11.

12.

13.

14.

15.

16.

17.

18.

19,

21

| 99,

ION 7
ENCES

Pitter, P., and J. Chudoba. Biodegradability of Or-
ganic Substances in the Aquatic Environment. CRC
Press, Boca Raton, Florida, 1990.

Reineke, W., and H. J. Knackmuss. Microbial Deg-
radation of Haloaromatics. Ann. Rev. Microbial.
42:263-287, 1988.

Ross, D. Application of Biological Processes to the
Clean Up of Hazardous Wastes. Presented at The
17th Environmental Symposium: Environmental
Compliance and Enforcement at DOD Installations in
the 1990’s, Atlanta, Georgia, 1990.

Sims, R. C. Treatment Potential for 56 EPA Listed
Hazardous Chemicals In Soil. EPA/600/6-88/001,
U.S, Environmental Protection Agency, 1988.

U.S. Environmental Protection Agency. A Compen-
dium of Technologies Used in the Treatment of Haz-
ardous Wastes. EPA/625/8-87/014, 1987.

U.S. Environmental Protection Agency. Engineering

Bulletin: In Situ Biodegradation Treatment. EPA/

540/0-00/000, unpublished.

U.S, Environmental Protection Agency. Engineering
Bulletin: Slurry Biodegradation. EPA/540/2-90/016,
1990.

U.S. Environmental Protection Agency. Guide for
Conducting Treatability Studies Under CERCLA, In-
terim Final. EPA/540/2-89/058, 1989.

US. Environmental Protection Agency. Methods for
Chemical Analysis of Water and Wastes. EPA/600/4-
791020, 1979.

. U.S. Environmental Protection Agency. Microbio-

logical Decomposition of Chlorinated Aromatic Com-
pounds. EPA 600/2-86/090, 1986.

U.S. Environmental Protection Agency. Preparation
Aids for the Development of Category IV Quality
Assurance Project Plans. EPA/600/8-91/006, 1991.

U.S. Environmental Protection Agency. ROD An-
nual Report: FY 1989, EPA/540/8-90/006, 1989.



If the remedy screening indicates that bioremediation is a
potential cleanup option then remedy selection studies
should be performed. Remedy selection testing is the
second level of testing. It is used to identify the
technology’s performance on a contaminant-specific basis.
Costs for these studies generally range from $50,000|to
$250,000. They yield data that verify that the technology
can meet expected clean up goals and can provide infor-
mation in support of the detailed analysis of the alternative
ie., the nine evaluation criteria).

During the remedy selection studies, microcosms designed
to simulate the proposed full-scale bioremediation system
are generally established. Specifically, the goals of the
remedy selection microcosms are to:
* — Estimate the rate at which the contaminants can

be biodegraded
° Determine the impact of parameters such as

nutrient addition, loading rate, and inoculation ot
the rate of biodegradation

¢ Estimate the cleanup levels achievable
* Develop design parameters for the next level of

* Develop preliminary cost and time estimates for
full-scale bioremediation.

If required, several bioremediation processes can be eval |
ated simultaneously to determine which process or comb
nation of processes is most appropriate for the cleanup
a given site. For example, if the affected materials at a si
can be effectively remediated with either a solid-phase

ee

* a slurry-phase biological treatment process, both of th

processes may be evaluated simultaneously. The biodeg-
radation rates measured during the solid-phase and slurry-
phase remedy selection evaluations can then be used fo
estimate the treatment time, equipment, and land area re-
quired by each treatment process. This procedure permit
determination of which process or combination of pt
cesses can achieve most cost-effectively, the requi

cleanup levels in the required period of time. If sufficient
design and cost information are acquired during the rem-
edy selection tests to permit full-scale system design, fur-
ther remedy design testing may be unnecessary.

Remedy design testing is the third level of testing in the
RI/FS process. These studies generally range from
$100,000 to $500,000. As discussed in the preceding
paragraph, remedy design studies are not always required.
When remedy design tests are performed, they are typi-
cally post-ROD. Therefore, if a remedy design program is
conducted, it should produce the data required for final
full-scale remedy design and costing. The remedy design
program is usually conducted on-site and should test all
equipment and processes so that accurate specifications
can be made for the full-scale system.

Example 7 demonstrates the decision process to proceed
from remedy screening, through remedy selection, and on
to remedy design. This example is a continuation of
Example 4 on page 20.

The size and scope of the remedy design program may be
decided by several factors including the quantity of mate-
tial available for testing, the complexity of the process,
cost, time, and equipment availability. An important fac-
tor that should not be overlooked when a remedy design
program is being set up is that the equipment must be
sized so that realistic scale-up factors can be used for
going to full-scale operation.

In conclusion, technologies generally are evaluated first at
the remedy screening level and progress through the rem-
edy selection to the remedy design level. A technology
may enter, however, at whatever tier or level is appropri-
ate based on available data on the technology and site-
specific factors. For example, a technology that has been
studied extensively may not warrant remedy screening to
determine whether it has the potential to work. Rather, it
may go directly to remedy selection testing to verify that
performance standards can be met.

Example 7.

Even though the reduction in PCP conbonaton during the remedy screening study
was sufficient to justify continuing to the remedy selection tier of treatability testing,
H the percentage of degradation, as compared to the control, indicated that process
changes were needed at the remedy selection tier. High PCP concentrations may
have been inhibiting microbial activity. [The RPM decided to investigate mixing less-
contaminated soil with the highly contaminated soil to lower PCP concentrations and
stimulate biodegradation. Remedy selection studies, using the design modifications
suggested by the remedy screening studies, resulted in an average removal of 93
percent of the PCP. Remedy design, studies were performed to provide design
information for a full-scale system, which was used to remediate the site successfully.

33



SECTION 2
TECHNOLOGY DESCRIPTION AND
PRELIMINARY SCREENING

This section describes the various full-scale aerobic vg
degradation technologies currently available and discusses
the information necessary to screen the technology prior
to commitment to a treatability test program. Subsection
2.1 describes several full-scale aerobic biodegradation sys-
tems that potentially can be used at Superfund sites. Sub-
section 2.2 discusses the literature and data base searche

required, the technical assistance available, and the review
of field data required to prescreen these technologies. Tech-
nology limitations are also reviewed in this subsection. |
2.1 TECHNOLOGY DESCRIPTION ;

Bioremediation generally refers to the breakdown of ot-
ganic compounds (contaminants) by microorganisms. In
situ, solid-phase, slurry-phase, soil-heaping, and compost:
ing biological treatment techniques are available for the
remediation of contaminated soils.“ Aerobic biodeg-
tadation can be used as the only treatment technology at a
site or along with other technologies in a treatment train,
Use of aerobic biodegradation, especially in situ, has bee
very limited at CERCLA sites. However, the technology
shows promise for degrading, immobilizing, or trans-
forming a large number of organic compounds com
monly found at CERCLA sites to environmentally
acceptable compounds.

As of fiscal year 1989, biodegradation has been selected
as a component of the remedy for 22 Superfund sites
having groundwater, soils, sludges, or sediments contami}
nated with various volatile organics; phenols; creosotes}
polynuclear aromatic hydrocarbons (PAHs); and benzene,
toluene, ethyl benzene, and xylene (BTEX) compounds:'

Information on the technology applicability, the latest per,
formance data, the status of the technology, and sources
for further information is provided in a series of | engineer!
" ing bulletins being prepared by the EPA Risk Reduction
Engineering Laboratory (RREL) in Cincinnati, Ohio.097}

2.1.1. In Situ Bioremediation

In situ bioremediation involves enhancing the microbial
degradation of contaminants in subsurface soil and water
without excavation of the contaminated soil. The technol-
ogy usually involves enhancing natural biodegradation pro-
cesses by adding nutrients, oxygen (if the process is
aerobic), and in some cases, microorganisms to stimulate
the biodegradation of contaminants. Moisture control may
be required to optimize biodegradation. If oxygen is the
rate-limiting parameter, oxygen sources such as air, high-
purity oxygen, or hydrogen peroxide are usually used to
increase the amount of oxygen available for biodegracla-
tion. Laboratory studies indicate the addition of methane
or other substrates may aid in the co-metabolic biodegra-
dation of low molecular weight chlorinated organics. Re-
cent evidence has shown that anaerobic processes that use
nitrate as a terminal electron acceptor may be effective for
the in situ treatment of benzene, toluene, xylenes, and
some PAHs.

Tn situ bioremediation is often used in conjunction with a
groundwater-pumping and soil-flushing system to circu-
late nutrients and oxygen through a contaminated aquifer
and associated soils. The process usually involves intro-
ducing aerated, nutrient-enriched water into the contami-
nated zone through a series of injection wells or infiltration
trenches and recovering the water down gradient. Water-
soluble contaminants are flushed out of the soil; less soluble
contaminants remain in the soil and are biodegraded. The
recovered water can then be reintroduced or disposed of
on the surface (Figure 2-1). Depending on the concentra-
tion of water-soluble contaminants in the recovered water,
additional treatment may be required before the water can
be disposed of or recycled to the soil treatment system.

In situ bioremediation has primarily been used for the
treatment of saturated soils; however, in a few instances,
the technology has been used to treat unsaturated soils.
The in situ bioremediation of unsaturated soils has typi-



Excavation

Microorganisms.
Nutrients .
Aeration | Plast
Spray Headers
Overhead

99

oo

Tp rehhouses

Soil Screening

Zone of
Incorporation’

c ee

Digtnibution
ystem

Treatment Area

Spray Nozzles
Sand

Con

inment Area

; Leachate Collection System

Figure 2-2. Solid-phase bioremediation.
|

the contaminants. The contaminants are degraded, immo-
bilized, or transformed to environmentally acceptable
components. ©

Decomposition and immobilization of the contaminants
occur within both the zone of incorporation, usually the
top 15 to 30 centimeters, and the underlying layers. The
zone of incorporation and the underlying soils, where ad-
ditional treatment and immobilization of the contaminants
occurs, are referred to as the treatment zone. The treat-
ment zone depth may be as much as 1.5 meters. Most of
the transformations, immobilization, and biodegradation
occur in the zone of incorporation.

2.1.3 Slurry-Phase Bioremediation
(Liquid/Solids Treatment)

In slurry-phase bioremediation, excavated contaminated
soil is typically placed in an on-site, stirred-tank reactor(s)
where the soil is combined with water to form a slurry.
The solids content of the slurry depends on the type of
soil, the type of mixing and aeration equipment available,
and the rates of contaminant removal that need to be

achieved. The water used in the process can be contami-
nated surface or ground water, thus facilitating the simul-
taneous treatment of contaminated soil and water. If
required, nutrients and microorganisms are added to the
| _ slurry, which is then aerated and agitated to optimize con-
tact between the microorganisms, nutrients, and oxygen
so that efficient biodegradation of the contaminants can
occur. The process can be operated in either a batch or a
continuous mode (Figure 2-3).

As with solid-phase bioremediation, the process can be
designed to contain and treat volatile organic com-
pounds. Slurry-phase bioremediation systems can be
used to treat sludges and sediments in existing lagoons
and impoundments, thus eliminating the need for soil
excavation (Figure 2-4). An impermeable layer should
be present under the slurry-phase system to prevent
contaminant migration.

2.1.4 Soil Heaping
Soil heap bioremediation involves piling contaminated soil

in heaps of several meters in height. Aeration is usually
provided by pulling a vacuum through the heap. Simple

a


EPA/540/2-91/013A.
duly 1991

GUIDE FOR CONDUCTING TREATABILITY STUDIES
UNDER CERCLA: AEROBIC BIODEGRADATION
REMEDY SCREENING

INTERIM GUIDANCE

US. Environmental |Protection Agency
Risk Reduction Engineering Laboratory
Office of Research and Development
Cincinnati, Ohio 45268

and
Office of Emergency and Remedial Response

Office of Solid Waste and Emergency Response
Washington, D.C. 20460

&B Printed on Recycled Paper



CONTRACTOR or WORK QUALITY ASSURANCE MANAGER
ASSIGNMENT MANAGER * Overseé Quality Assurance

» Report to EPA Remedial © Prey "
pare applicable sections

Project Manager of Report and Work Plan
* Supervise overall project

MIGROBIOLOGIST (ENVIRONMENTAL CHEMIST

‘SCIENTIST/ENGINEER or
BIOENGINEER) . Oversea one collection

* Oversee Treatabillty ¢ Prepare applicable sections

Study execution
* Prepare applicable sections of Report and Work Plan

of Report and Work Plan

LAB TECHNICIAN
* Perform Treatability Study
* Sample collection and analysis

Figure 4-2. Organization chart.

lytical costs which are directly tied in with the number of _rather than GC/MS methods also should help to minimize
replicates, One method to minimize costs is to use an costs. Table 4-3 summarizes the major cost elements
inexpensive analysis of an indicator parameter and to per- _ associated with remedy screening treatability tests for bio-
form a limited number of analyses for the more expensive degradation of a contaminated site.

volatile and semi-volatile priority pollutants. Use of GC

Table 4-3. Major Cost Elements Associated with Aerobic Biological
Remedy Screening Treatability Studies

Cost Range
Cost Element (thousands of dollars)

Work Plan Preparation 1-5
SAP Preparation 1-5
Field Sample Collection 1-5
Field Sample Chemical Analysis : 2-10
Laboratory Setup/Materials 2-10
Treatability Test Chemical Analysis 2-10
Data Presentation/Report 1-5

TOTAL COST RANGE 10- 50



Technology
Potentially
Viable?

MANAGEMENT DECISION FACTORS:

* State and Community Acceptance

* Schedule Constraints
* Additional Data.

Treatability Management

Decision Factors}

Remedy
Screening
Studies

Remedy
Selection Screen
Studies Out

Detailed Analysis
of Alternatives

Figure 3-1. Flow diagram of the tiered approach.







In general, for sampling and analysis of soils and slud-
ges, the analytical variability can be quite high (on the
order of 20 to 50 percent). Therefore, a sufficient num-
ber of samples must be taken for statistically significant
effects to be observed. Additional information on sample
size selection is available in many statistical text-
books.245K)

‘The type I error probability is the chance of the experiment
indicating that there is a statistically significant treatment
effect when, in reality, there is not. Conversely, the type I
error probability is the chance of not detecting a significant
treatment effect when, in reality, the treatment was effec-
tive. Traditionally, experimental designs have been con-
structed so that these error probabilities are on the order of
5 percent (i¢., 95 percent confidence levels). This error
probability is not appropriate for the remedy screening scale
of treatability testing. Error rates on the order of 10 to 20
percent (i¢., 80 to 90 percent confidence levels) are more
consistent with the philosophy of remedy screening.

It is beyond the scope of this document to go into great
detail on experimental design but many good texts on the
subject are available.

An example of a simple experimental design is included
in Example 5.

4.3 EQUIPMENT AND MATERIALS

The Work Plan should specify the types of equipment
and materials to be used during the treatability test. For
example, the size and type of glassware to be used
during the test should be specified. Standard laboratory
methods normally dictate the types of sampling contain-
ers that can be used with various contaminant groups.
The RPM should consult such references for the appro-
priate containers to be used for the treatability studies.
Normally, glass reactors with Teflon® fittings should be
used. Stainless steel also can be used with most con-
taminants. Care should be taken when using various
plastic containers and Tygon® tubing. Such materials
will adsorb many contaminants and also can leach plas-
ticizer chemicals, such as phthalates, into the soil ma-
trix. Typically, such analytical equipment as gas
chromatograph (GC), high-pressure liquid chromatograph
(HPLC), total organic carbon (TOC) analyzers, and pH
meters will be required.

Example 5. Bioremediation Study

Twenty-four 20-gram samples of soil containing approximately 100 ppm phenol were
added to separate 500 ml flasks along with 80 ml of water containing phosphate buffer
(pH = 7.0), ammonium sulfate, and trace metals. Twelve of the resulting soil slurries
were inoculated with a suspension containing approximately 10* phenol degrading
bacteria/ml. The other 12 flasks were inoculated and then “sterilized” with mercuric
chloride to form the control group. The test and inhibited control flasks were stoppered
and stirred at moderate speed on stirring plates while incubating at 20°C. Three test
flasks were immediately sacrificed (T,) by adding 100 ml of methanol and shaking
vigorously to extract the phenol for analysis. One ml subsamples from each flask were
centrifuged at high speed in a microcentrifuge to remove soil particles. Phenol was
quantified via high-pressure liquid chromatograph. At each of three subsequent time
points (T,, T,, T,), three additional test flasks were sacrificed and subsampled as
previously described. Three inhibited control flasks were also sacrificed at each time
point. The mean phenol concentration of the three test flasks was compared to the
mean phenol concentration of the three control flasks at each time point to see if
significant biodegradation was occurring.



SEC

TION 6

TREATABILITY DATA INTERPRETATION

This section is designed to help the RPM or contractor to
interpret treatability data in screening and selecting a rem-
edy. The information and results gathered from the rem-
edy screening are used to determine if bioremediation is a
viable treatment option and to determine if additional rem-
edy selection and remedy design studies are needed prior
to the implementation of a full-scale bioremediation pro-
cess. A threshold of greater than 20 percent reduction in
the concentrations of the compounds of concern, com-

pared to the abiotic control, indicates that bioremediation
is potentially a viable cleanup method and further testing
is warranted. For some compounds or sites, a period of
time longer than the typical 6-8 weeks may be indicative
of a successful remedy screening study. An example
method for interpreting the results from a remedy screen-
ing treatability study is provided below. Other valid sta-
tistical methods may be used as appropriate.

Ex

average hydrocarbon concentration in
200 ppm (T,), a reduction of greater |t!

TABLE 6-1. Hydrocarbon i

In a remedy screening treatability study for soil contaminated with a solvent, the
average solvent concentrations in both the inhibited control andinthe biologically active
system were 1300 ppmatT,. The average solvent concentration in the inhibited contro!
was reduced to 550 ppm ty, a reduction of greater than 57 percent (Table 6-1). The

‘oncentration (ppm) Versus Time

1 biologically active system was reduced to
han 84 percent for the same time period.

SAMPLE T T, T, T,
Inhibited Control (C)
Replicate 1 1220 1090 695 875
Replicate 2 1300 854 780 580
Replicate 3 1380) 1056 688 495.
Mean Value 1300(Gi,) 1000G,) 721) 850)
Concentration Change ty -300  -579-~ 750
G,-Gi) =0,1,2,3)
Bioreactor (C,)
Replicate 1 1327 982 550 225
Replicate 2 1320 865 674 310
Replicate 3 1253 203. 666, 65
Mean Value 1300|(GB,) 850 ) 630 Cb) 200 (Ch)
Concentration Decrease 0 -450 - 670 - 1100
,- Cb) (T=0,1,2,3)



Example 3.

A site contains 27,000 cubic yards of soil|contaminated with chlorinated hydrocarbons.
A remedy screening study is being performed to determine if bioremediation is a viable
cleanup method for the soil. The objectives of the study in this case would be to determine
if biological processes could reduce the ai Yerage chlorinated hydrocarbon concentration
by greater than 20 percent, as compared a chemically inhibited control, in a 6-week
study. The mean contaminant concentration, corrected for the abiotic control, shows a
38 percent reduction after two months. biodegradation is
a potentially viable technology and that remedy selection studies are warranted.

TM RPM decides that aerobi

|
generally are of moderate cost (e.g., $50,000-$250,000)
and may require several weeks to months to complete!
They yield data that verify that the technology is likely to,
meet expected cleanup goals and can provide information|
in support of the detailed analysis of the alternative (i.c.,|
seven of the nine evaluation criteria).

The remedy selection tier of testing for aerobic biodegrada-,
tion normally consists of bench-scale tests which provide,
sufficient experimental controls such that a quantitative mass-|
balance can be achieved. Such studies often incorporate,
volatile traps. Toxicity testing of residual contaminants and|
intermediate degradation products is usually required. At
the remedy selection level, reduction of organic contami-
nants to the cleanup goals, over a 1- to 3-month period,
would signify the treatability test was a success. The exact)
removal efficiency specified as the goal for the remedy
selection test is site specific.

Pilot-scale testing may be needed for remedy selection, es-
pecially for complex sites where in situ biodegradation is,
being considered. RREL is planning to develop additional
guidance on remedy selection treatability studies for aerobic
biodegradation.

3.2.3 Remedy Design

performance to a higher degree than the remedy selection
studies 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 non-mobile technologies. In some cases, remedy
design tests may be a continuation of remedy selection
tests using the same apparatus. A complete mass balance,
including all non-biological pathways, should be performed
at this level of testing. Typical testing periods are from 2
to 6 months. For more complex sites (.g., sites with
different types of contaminants in different areas or with
different geological structures in different areas), longer
testing periods may be required.

The goal of this tier of testing is to confirm the cleanup
levels and treatment times specified in Subsection 4.1.1.
This is achieved by operating a field unit under conditions
similar to those expected in the full-scale remediation project.

Data obtained from the pilot-scale tests should be used as
follows:

* Design full-scale unit

° Determine feasibility of aerobic biodegradation

based on target cleanup goals
Remedy design testing is the third level of testing. It is . .
used to provide quantitative performance, cost, and design * Refine cleanup time estimates
information for remediating a site. This level of testing ¢ — Refine cost predictions.

also can produce data required to optimize performance.
These studies are of moderate to high cost (e.g., $100,000-
$500,000) and’ may require several months or more to
complete. Remedy design studies yield data that verify

17

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



SECTION 1
INTRODUCTION

1.1. BACKGROUND

Section 121(b) of the Comprehensive Environmental Re-
sponse, Compensation and Liability Act (CERCLA) man-
dates the Environmental Protection Agency (EPA) to select
remedies that “utilize permanent solutions and alternative
treatment technologies or resource recovery technologies
to the maximum extent practicable” and to prefer remedial
actions in which treatment that “permanently and signifi-
cantly reduces the volume, toxicity or mobility of the
hazardous substances, pollutants, and contaminants is a
principal element.” Treatability studies provide data to
support treatment technology selection and remedy imple-
mentation and should be performed as soon as it is evident
that insufficient information is available to ensure the qual-
ity of the decision. Conducting treatability studies early in
the remedial investigation/feasibility study (RI/FS) pro-
cess should reduce uncertainties associated with selecting
the remedy and provide a sounder basis for the Record of
Decision (ROD). Regional planning should factor in the
time and resources required for these studies.

Treatability studies conducted during the RI/FS phase in-
dicate whether a given technology can meet the expected
cleanup goals for the site, whereas treatability studies con-
ducted during the remedial design/remedial action (RD/
RA) phase establish the design and operating parameters
for optimization of technology performance. Although the
purpose and scope of these studies differ, they comple-
ment one another (i.e., information obtained in support of
remedy selection may also be used to support the remedy
design). °

This document refers to three levels or tiers of treatability
studies: remedy screening, remedy selection, and remedy
design. Three tiers of treatability studies are also defined in
the Guide for Conducting Treatability Studies Under
CERCLA, Interim Final, referred to as the “generic guide”
hereafter in this document. The generic guide refers to the
three treatability study tiers, based largely on the scale of
test equipment, as laboratory screening, bench-scale testing,
and pilot-scale testing. Laboratory screening is typically
used to screen potential remedial technologies and is equiva-

lent to remedy screening. Bench-scale testing is typically
i used for remedy selection, but may fall short of providing
| enough information for remedy selection. Bench-scale stud-
ies can, in some cases, provide enough information for full-
scale design. Pilot-scale studies are normally used for
remedial design, but may be required for remedy selection
| in some cases. Because of the overlap between these tiers,
| and because of differences in the applicability of each tier to
| different technologies, the functional description of treat-
ability study tiers (i.e., remedy screening, remedy selection,
and remedy design) has been chosen for this document.

Some or all of the levels of treatability study testing may
be needed on a case-by-case basis. The need for and the
level of treatability testing required are managerial deci-
sions in which the time and cost necessary to perform the
testing are balanced against the risks inherent in the deci-
sion (e.g., selection of an inappropriate treatment alterna-
tive). These decisions are based on the quantity and quality
of data available and on other decision factors (¢.g., State
and community acceptance of the remedy and experience
with the technology at other sites). The use of treatability
i studies in remedy selection is discussed further in Section
3 of this document,

1.2 PURPOSE AND SCOPE

This guide is designed to ensure a credible approach is
taken to evaluate whether aerobic biodegradation should
be considered for site remediation. This guide discusses
| only the remedy screening level. Remedy screening stud-
jies are designed to provide a quick and relatively inexpen-
sive indication of whether biological degradation is a
potentially viable remedial technology. Remedy selection
| studies will also be required to determine if bioremediation
is a viable treatment alternative for a site. The remedy
screening evaluation should:

* Provide a preliminary indication that reductions in
contaminant concentration are due to biodegrada-
tion and not abiotic processes such as photo
decomposition, volatilization, or adsorption, and



Nutrients
Aeration
| Microorganisms

Injection Wells

Treatment

Optional

Mixing -=—=

—
a

U1 Low Permeability Bedrock
oo

Figure 2-1. In situ bioremediation of groundwater.

cally been limited to fairly shallow depths over groundwa-
ter that is already contaminated. The treatment of unsatur-
ated soils is difficult to control and relies on the use of percolation
techniques to introduce nutrient-adjusted water and vacuum
extraction techniques to enhance air exchange in the soil matrix.

In situ bioremediation treats contaminants in-place, elimi-
nating the need for soil excavation and limiting the release
of volatiles into the air. Consequently, the risks and costs
associated with materials handling are reduced or elimi-
nated. Furthermore, in situ bioremediation has the poten-
tial to clean up the source material responsible for the
groundwater contamination.

2.1.2 Solid-Phase Bioremediation

Solid-phase bioremediation (sometimes referred to as land
treatment) is a process that treats soils in an above-grade
treatment system using conventional soil management prac-
tices to enhance microbial degradation of contaminants.
Solid-phase bioremediation can be designed using shal-
low “tanks” to meet land-ban requirements.

Solid-phase bioremediation at CERCLA sites usually in-
volves placing excavated soil in an above-grade soil treat-
ment area. If required, nutrients and microorganisms are
added to the soil, which is tilled at regular intervals to
optimize aeration and contact between the microorgan-
isms and the contaminants. During the operation of a solid-
phase bioremediation system, pH, nutrient concentrations,
and moisture content are maintained within ranges condu-
cive to microbial activity (Figure 2-2). In some cases, the
contaminated soil has to be mixed with clean soil to re-
duce the concentration of contaminants to levels that do
not inhibit microbial activity. Solid-phase treatment sys-
tems can be modified to contain and treat soil leachate by
adding underdrain and liquid treatment systems. Volatile
organic compounds (VOCs) can be contained by adding
an optional cover. Conventional VOC treatment can be
added as part of a treatment train.

A variety of processes influence the fate of contaminants
in solid-phase treatment systems. These include physical
and chemical processes (such as leaching, adsorption, des-
orption, photodecomposition, oxidation, volatilization, and
hydrolysis) and biodegradation. The physical, chemical,
and biological properties of the contaminants and soil in-
teract with site-specific variables to influence the fate of