NCD980840409_19940201_Charles Macon Lagoon & Drum_FRBCERCLA RA_Anaerobic Bioremediation Study Work Plan-OCR

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IRECIEIVED
FEB O 7 1994
SUPERFUND SECTION
CONFIDENTIAL BUSINESS INFORMATION
ANAEROBIC BIOREMEDIATION
STUDY WORK PLAN
Macon/Dockery Site
Richmond County, North Carolina
Prepared by:
DuPont Environmental Remediation Services
6324 Fairview Road
Senlor Environmental Enginee1
Charlotte, NC 28210
[phone]
DERS Project Number 2785
~:frzf:jf,/4,
Senior Environmental Scientist
DuPont Environmental Remediation Services · I
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TABLE OF CONTENTS
1.0 INfRODUCTION ................................................................................ 1
1.1 Background ................................................................................... 1
1.2 Previous Studies and Relevant Information .............................................. 1
1. 3 Objectives ..................................................................................... 2
2.0 ANAEROBIC BIOREMEDIATION TECHNOLOGY .......................................... 3
2.1 Anaerobic Bioremediation Review ........................................................ 3
2.2 Anaerobic Bioremediation Application .................................................. .4
3.0 BIOREMEDIATION STUDY WORK PLAN .................................................... 6
3.1 Site Assessment And Characterization ................................................... 7
3.2 Laboratory Optimization Study ............................................................ 8
3.2.1 Study Area ....................................................................... 8
3.2.2 Methodology ..................................................................... 9
3.2.3 Data Analysis and Reporting ................................................ 10
3.3 Groundwater Tracer Study ............................................................... 10
3.3.1 Tracer Study Wells ........................................................... 10
3.3.2 Methodology ................................................................... 12
3.3.3 Data Analysis and Reporting ................................................ 12
3.4 Pilot-Scale Field Test ..................................................................... 12
3.4.1 Study Area ..................................................................... 13
3.4.2 Methodology ................................................................... 13
3.4.3 Data Analysis and Reporting ................................................ 14
4.0 SCHEDULE .......................................................................................... 15
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5.0 REFERENCES ...................................................................................... 16
DuPont Environmental Remediation Services · iii
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Table 1-1
Table 3-1
LIST OF TABLES
Summary of Source Area Groundwater Parameters
Pilot Study Indicator List-Parameters and Methods
DuPont EnvironmenJal Remediation Services · iv
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Figure 3-1
Figure 4-1
LIST OF FIGURES
Proposed Monitoring Well Locations
Project Schedule
DuPont Environmental Remediation Services · v
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LIST OF APPENDICES
Appendix A Procedures for Tracer and Substrate Additions
DuPont Environmental Remediation Services · vi
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1.0 INTRODUCTION
January 19, 1994
Project Number: 2785
Page I
This report presents a work plan for evaluating the potential application of in-situ anaerobic
bioremediation for chlorinated aliphatic hydrocarbons in groundwater at the Macon/Dockery
Superfund site. This section presents background on the site and identifies the specific objectives
of the work plan.
1.1 Background
The Macon/Dockery Site is located approximately I. 6 miles southwest of the town of Cordova in
Richmond County, North Carolina. The site comprises two non-contiguous tracts. The first,
known as the Macon Tract, is 40-acres in dimension. The second, referred to as the Dockery
Tract, is 570 acres in size.
The area of focus in this work plan is the portion of the Macon property known as the Upper
Macon area. A Remedial Investigation (Sirrine Environmental, 199 I) conducted in this area
discovered several chlorinated aliphatic compounds, including tetrachloroethene (PCE) and
trichloroethene (TCE) in the surficial saturated unit.
The United States Environmental Protection Agency (USEP A) has issued a Unilateral
Administrative Order for Remedial Design and Remedial Action for the Macon/Dockery Area.
Specific work elements in this Order include control of groundwater in the Upper Macon Area. A
preliminary design for site groundwater control and treatment (RMT, 1993) has recently been
submitted to USEP A.
1.2 Previous Studies and Relevant Information
Numerous investigations (on a regional and site-specific scale) have produced information related
at the hydrogeologic, geologic, and geotechnical conditions within the study area. A June 29,
1993 groundwater sampling event involving five monitoring wells at Upper Macon was
conducted during the Preliminary Design Investigation to gain more information on subsurface
conditions as it might pertain to microbial degradation of PCE and TCE. Previous data had
indicated that chlorinated hydrocarbons were degrading into less-chlorinated substances as shown
by the presence of vinyl chloride in source area wells. The major findings of this sampling are
summarized in the RMT Preliminary Design report ( 1993) and are as follows:
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January 19, 1994
Project Number: 2785
Page2
• The presence of cis-1,2-dichloroethene and ethene provide strong evidence that biological
processes are mineralizing PCE and TCE.
• The abundance of dissolved iron and manganese in the Upper Macon aquifer indicates that
biological reduction of these compounds is potentially occurring and that iron and manganese
act as electron acceptors for subsurface microorganisms which degrade PCE and TCE.
• The presence of sulfides and lack of sulfates strongly indicate that sulfates were previously
used as an electron acceptor by microorganisms but have been reduced to sulfides and largely
depleted.
Table 1-1 summarizes groundwater data from source area wells.
1.3 Objectives
The objectives of the work plan are to:
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Determine if existing anaerobic microorganisms are capable of completely biodegrading
the chlorinated aliphatic compounds.
Estimate reaction-rate constants for enhanced anaerobic biodegradation;
Identify any lack of nutrients in the formation that limits microbial growth;
Identify the substrate that provides the most rapid and complete biodegradation;
Evaluate optimized bioremediation in the field; and
Provide recommendations for proceeding to a full-scale program, if appropriate .
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January 19, 1994
Project Number: 2785
Page 3
2.0 ANAEROBIC BIOREMEDIATION TECHNOLOGY
2.1 Anaerobic Bioremediation Review
Anaerobic bioremediation is a viable technology for the reduction of chlorinated aliphatic
constituents such as those found at the Macon/Dockery Superfund site. The predominant organic
contaminants at the site are tetrachloroethene (PCE), trichloroethene (TCE), I, 1-dichloroethene
(!, 1-DCE), 1,2-dichloroethene (1,2-DCE), trichloroethane (TCA), dichloroethane (DCA) and
vinyl chloride (VC). Based primarily on DuPont's experiences and support by published research,
all of these organic contaminants are known to be biodegradable under anaerobic conditions.
Chlorinated aliphatic compounds are biodegradable under anaerobic conditions. During anaerobic
biodegradation, chlorines are removed from chlorinated aliphatic compounds in a step-wise
manner (e.g., PCE is reduced in the sequence: PCE to TCE to 1,2-DCE to VC to ethene) in a
process known as reductive dehalogenation. The biodegradation of chlorinated aliphatic
compounds will occur under either sulfate-reducing or methanogenic conditions. Under sulfate-
reducing conditions, the microbes convert sulfate to hydrogen sulfide, typically with an organic
compound or molecular hydrogen serving as the electron donor and the chlorinated aliphatic
compound as the electron acceptor. Under methanogenic conditions, bacteria biodegrade
chlorinated aliphatic compounds while using a limited number of simple organic substrates
( e.g., acetate or methanol) as electron donors and either carbon dioxide or bicarbonate as electron
acceptors. Chlorinated aliphatic compounds can be completely dechlorinated under anaerobic
conditions, without the accumulation of intermediate compounds such as DCE or VC, resulting in
the formation of innocuous end products such as ethylene and carbon dioxide.
In order for biodegradation to occur, environmental conditions, such as pH, redox, and
temperature, must be suitable for microbial growth. The primary requisites for biodegradation
include: a carbon source; electron acceptors, and; nutrients (Lee et al. 1988). The carbon source,
usually referred to as "the substrate", provides energy and carbon for microbial growth and can
serve as an electron donor. Electron acceptors used for biodegradation include: oxygen; sulfate;
nitrate; iron; and manganese. Nutrient requirements include: nitrogen; phosphorus; potassium;
and trace elements. The redox potential of the groundwater will have a significant impact on the
type of electron acceptor and microbial activity predominating in the aquifer.
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January 19, 1994
Project Number: 2785
Page 4
A wide variety of organic substrates have been reported to serve as electron donors during the
biodegradation of chlorinated aliphatic compounds. Gibson and Sewell (1992) reported that PCE
dechlorination occurred with lactate, ethanol, propionate, crotonate, and butyrate as substrates.
Di Stefano et al. (I 991) reported methanogenic reductive dechlorination using methanol as the
substrate. Beeman et al. (in press) successfully used benzoate under sulfate-reducing conditions
for the in-situ dechlorination of PCE. In unpublished studies conducted at DuPont's Glasgow
laboratories, trimethylamine, yeast extract, acetate and benzoate have been used successfully. It
has been suggested that any compound that increases the hydrogen pool may be a viable candidate
for use as an electron donor (Gossett et al., 1992).
Anaerobic biotreatment processes have the following advantages over aerobic processes:
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Anaerobic electron acceptors have a higher solubility in water than oxygen. Therefore,
they are less likely to limit the rate of degradation;
Anaerobic electron acceptors generally produce less microbial biomass, which
decreases the potential for aquifer plugging; and
• Many anaerobic microorganisms possess metabolic capabilities not found in aerobes;
therefore, they can degrade some compounds, such as chlorinated aliphatic compounds
that are not readily biodegradable under aerobic conditions.
2.2 Anaerobic Bioremediation Application
Natural anaerobic biodegradation of the contaminants at the Upper Macon site appears to be
occurring based on the presence in the groundwater of the PCE and TCE biodegradation
products cis-1,2-dichloroethene (cis-1,2-DCE), vinyl chloride, and ethene. The natural
biodegradation process can likely be accelerated by supplying amendments that may be
limiting microbial growth, and thereby, enhance degradation to innocuous end products.
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January 19, 1994
Project Number: 2785
Page5
The amendments necessary to enhance bioremediation at the Upper Macon site will be
determined during the laboratory optimization evaluation which will be performed as part of
this study and is described in subsequent sections of this workplan. It is anticipated that the
amendments would include an organic substrate (such as a simple sugar), an electron acceptor
(such as sulfate) and inorganic nutrients (such as nitrogen and phosphorus). An Injection Well
permit will be obtained from the Groundwater Section of NCDEHNR prior to injecting any
amendments or tracers into the groundwater. Once approval is obtained, the amendments
would be added to groundwater through an injection well and move through the treatment zone
with groundwater flow. Downgradient sampling points would be used to monitor groundwater
parameters and contaminant biodegradation in order to assess performance. Following the
tracer study, an estimate of travel time to the planned site containment system will be
provided.
Of potential concern is the production and migration of vinyl chloride, which may move
more rapidly through the aquifer than the parent compounds (PCE, TCE). It has been
DuPont's experience at other sites where DuPont has successfully conducted similar pilot
activites that vinyl chloride will be biodegraded to ethene within the study area. Both vinyl
chloride and ethene were found in well MW-09 at the Upper Macon site during the March
1993 Sampling Event, indicating that vinyl chloride is being degraded as it is produced
during perchloroethene and trichloroethene degradation. Additionally, a plume
containment system is scheduled to be constructed 550 feet downgradient of MW-09 in
1994. Any vinyl chloride generated during the pilot study and migrating downgradient will
move approximately as fast as the 60-foot per year average groundwater velocity calculated
from area aquifer tests. This compound would therefore require several years to migrate to
the boundary of the plume contaiment system. Any vinyl chloride not degraded in-situ will
be captured in the containment system and subsequently treated.
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3.0 BIOREMEDIA TION STUDY WORK PLAN
January 19, 1994
Project Number: 2785
Page 6
A brief overview of the proposed activities is presented in this section. Further detail is provided
in subsequent sections. The treatability testing consists of the following four components:
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Site assessment and characterization;
Optimization studies;
• Tracer study; and
• In-situ pilot test.
The project commences with site assessment and characterization to verify conditions are
favorable for anaerobic bioremediation. The site assessment and characterization consists of
reviewing groundwater analytical data; collecting additional data to fill data gaps; determining the
presence of metabolic end products; and determining existing nutrient and other environmental
conditions. In addition, the hydrogeological conditions will be evaluated and groundwater
modeling will be conducted in support of the pilot field study. The results of this assessment will
provide the preliminary information needed to proceed with the subsequent studies.
The optimization study will be conducted in the laboratory to determine the most favorable
conditions for biodegradation under site-specific conditions. The information obtained from the
laboratory optimization study will be used for designing and operating the field pilot test.
The tracer study is designed to confirm groundwater flow direction and travel times among wells.
The information obtained from the tracer study will be used to optimize the operation of the in-
situ pilot test and to evaluate the effectiveness of the pilot test.
The field pilot test will be conducted to evaluate in-situ bioremediation at the site. The results of
the other study components (site assessment and characterization, laboratory optimization study,
and tracer study) will be used to establish a field study area, the location of injection and I monitoring points, and the groundwater amendments for the field bioremediation demonstration.
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The pilot test will provide an understanding of technology implementation and effectiveness. The
results of the pilot testing will determine the potential of anaerobic bioremediation as a
supplemental remedial activity for the Upper Macon site. Based on pilot test results, additional
studies may be recommended to obtain additional information prior to full-scale implementation
of this technology.
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January 19, 1994
Project Number: 2785
Page 7
The current site-specific Health and Safety Plan will be followed. Sample quality assurance and
quality control (QA/QC) developed for the site will be employed for pilot study. The laboratory
optimization study will be conducted entirely within DuPont's Glasgow laboratory. Frequency for
QA/QC sample collection, decontamination procedures, and analytical protocols and reporting
will be consistent with those specified in the site plan.
3.1 Site Assessment And Characterization
During the site assessment and characterization, groundwater data will be examined for evidence
of biological activity, biodegradation products, and environmental conditions that may affect
biodegradation. If needed, groundwater samples will be collected from select monitoring wells
and analyzed for the constituents of concern, metabolic end products, electron acceptors,
nutrients, and other parameters influencing microbial growth and characterizing aquifer chemistry.
Historic groundwater elevation data will be evaluated to assist with selecting piezometer locations
for the pilot study. Groundwater modeling will be used to assist in determining amendment
concentrations.
The specific objectives of the site assessment and characterization are to:
• Verify occurrence of anaerobic biodegradation of the chlorinated aliphatic compounds;
• Determine potential limiting factors for the metabolic activity of the indigenous
microorganisms; and
• Complete the groundwater chemistry characterization necessary for implementing in-situ
bioremediation at the site.
Based on the current groundwater analytical data, wells MW06, MW09, and MW13 have been
selected for monitoring during the first phase of this work plan. These wells were selected based
on their capacity to characterize groundwater at a variety of depths, provide accessibility for the
installation of downgradient piezometers, and provide sufficient historical groundwater-quality
data.
An evaluation of subsurface conditions at the selected wells will be conducted by reviewing
drilling logs, groundwater-quality data, and other available hydrogeologic data. This phase has
been largely completed as described in Section 1.2. The results will be used to more precisely
select the study area and injection and monitoring points for the tracer study and
in-situ pilot test.
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January 19, 1994
Project Number: 2785
Page 8
The proposed pilot test methodology will be based upon the site assessment, tracer studies,
and lab optimization studies that will be conducted. Agency (USEPA, NCDEHNR) review
and approval will be sought for specific methodology for the pilot test prior to
implementation. Additionally, all permits applicable to this study will be obtained from
NCDEHNR prior to any planned activity.
3.2 Laboratory Optimization Study
DERS will conduct a laboratory optimization study to determine the optimal conditions for the
microbial anaerobic biodegradation of constituents of concern. The combination of electron
donors and acceptors providing the maximum rate and extent of biodegradation of the
contaminants will be determined. The optimization study will be conducted in the DuPont
Glasgow laboratory using groundwater and aquifer soil samples collected from the Upper Macon
site.
Specific objectives of the optimization study are to determine:
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Whether indigenous microorganisms can effectively biodegrade the chlorinated aliphatic
constituents of concern;
Whether methanogenic or sulfate-reducing conditions provide the maximum
biodegradation activity for the chlorinated solvents at the Macon/Dockery site; and
Which substrate ( electron donor) provides the most rapid and complete biodegradation
and the optimal rates of anaerobic biodegradation of chlorocarbons that can be achieved.
3.2.l Study Area
Groundwater and aquifer soil will be collected from areas known to contain elevated
concentrations of chlorinated aliphatic compounds. Based on a review of existing site data, the
proposed study area is near well MW09.
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3.2.2 Methodology
January 19, 1994
Project Number: 2785
Page9
Groundwater and aquifer soil samples will be collected following the procedures presented in the
Site Quality Assurance Project Plan (QAPP; RMT, 1992). Aquifer soil will be collected during
installation of piezometers with a drilling rig and split-spoon sampling procedures.
After collection, the aquifer soil samples will be purged with nitrogen to maintain low oxygen
conditions. All samples will be delivered to the DuPont Glasgow laboratory without refrigeration.
to preserve indigenous microorganisms.
Duplicate microcosms will be spiked with IO percent soil and 90 percent groundwater containing
5 milligrams per liter (mg/I) each of 1, I, 1-TCA and PCE in each treatment. The treatments will
include a mercuric chloride (HgCI 2) poisoned control ( negative control) and an unamended
treatment without additional electron donors. An inorganic nutrient solution containing 25 mg/I
nitrogen and 5 mg/I phosphorus will be added to each treatment. Both sulfate-reducing and
methanogenic conditions will be evaluated. The electron donors that will be used are acetate,
trimethylamine, and yeast extract. The concentrations of TCA, I, 1-DCA and 1,2-DCA,
chloroethane, PCE, TCE, cis and trans 1,2-and I, 1-dichloroethene ( cDCE, tDCE, and I, 1-DCE),
and VC will be analyzed by gas chromatography and mass spectroscopy (GC/MS) EPA 624.
Final metabolic end products (ethene, ethane, and methane) will also be monitored. The
laboratory evaluation will be conducted for approximately 12 weeks.
While a microcosm spiked with 10% soil and 90% water is not completely representative of
subsurface conditions, this experimental configuration will adequately test the study
hypothesis, which is whether or not reductive dechlorination is the mechanism by which
perchloroethene and trichloroethene are being degraded. While the rates of
biodegradation may differ because there will be lower numbers of microbes present in the
microcosms than would be present in the subsurface, it is expected that the
biotransformation processes should be the same as those presently thought to be occurring
in the Upper Macon aquifer. A larger volume of liquid than soil is required to enable
repeated sampling of the microcosms to allow for statistical analysis. The lab studies are
designed to look at the electron acceptors and organic substrates which will augment
naturally-occurring conditions so that biodegradation of the compounds will be enhanced.
Once these have been identified, a field pilot will be conducted to confirm the efficacy of the
selected approach. The specific approach regarding the methodologies to be employed for
the field pilot study will be documented and submitted for agency review and approval
prior to implementation.
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January 19, 1994
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The optmuzation study analyses will be conducted by DuPont's Glasgow laboratory using
Environmental Protection Agency (EPA) Method SW-846 protocols and QA/QC procedures.
The Glasgow laboratory will provide a more rapid turnaround time for the analyses, which is
necessary to adjust sampling frequency, than is available from an EPA contract laboratory
program (CLP) laboratory.
3.2.3 Data Analysis and Reporting
Data will be compiled and analyzed to determine which amendments promote the most rapid and
complete degradation of the chlorinated aliphatic contaminants. The combination of the substrate
and electron acceptor providing the maximum dechlorination will be used in the subsequent field
pilot test. A technical memorandum will be prepared and submitted to USEP A that summarizes
the results of this work. A schedule for this submittal and other project milestones is presented as
Figure 4-1.
3.3 Groundwater Tracer Study
A groundwater tracer study will be conducted prior to and concurrent with the bioremediation
field test. The goals of the tracer study will be to demonstrate that groundwater flows from the
injection well to the downgradient monitoring points and to estimate groundwater constituent
travel time in the aquifer. Once flow direction and rate have been confirmed, the additional
piezometers will be installed, if needed, to effectively monitor the treatment zone.
3.3.1 Tracer Study Wells
One injection well ( existing well MW09) and six piezometers, as shown in Figure 3-1, will be
used in the tracer study and the subsequent field test. Based on evaluation of the existing data,
the area in the vicinity of well MW09 has an active microbial community that is producing the
metabolic byproducts expected of the anaerobic bioremediation process.
Piezometers will be constructed of 3 04 stainless steel screen. Borings will be advanced using a
hollow-stem auger and pneumatic air hammer. The compressed air used to operate the air
hammer will be cooled and filtered by an inline air filter to remove particulate materials and
volatile constituents prior to introduction of the air downhole. The aquifer will be fully screened
to bedrock. On the basis of prior site experience, a screen slot size of 0.01 inch will be used.
Screen will be machine slotted.
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January 19, 1994
Project Number: 2785
Page II
Prior to installation, monitoring well casing and screen materials will be steam-cleaned and
decontaminated according to the procedures described in the Site QAPP. During transport fro
the decontamination area to the well site, the materials will be wrapped in plastic and will remain
wrapped until ready for installation.
Annular space around the well screen will be packed with clean quartz sand appropriate to the
well screen slot size. A minimum of six inches of filter pack material will be placed under the
bottom of the well screen to provide a firm footing and unrestricted flow under the well screen.
The sand pack will emplaced by tremie and extend approximately two feet above the top of the
screen. If the top of the sand pack is less than 50 feet below land surface, the top of the sand
pack will be seated with bentonite pellets dropped down the annular space. The remaining
annular space will then be grouted to approximately two feet below the land surface. A framed
and sloping concrete pad will be poured around each piezometer. Each piezometer will be
lockable.
Aquifer soil samples will be collected with split spoon samplers. These samples will be used to
establish baseline conditions and will serve as the study material for the laboratory optimization
study. Drill cuttings will be containerized and placed in labeled DOT-approved 55-gallon drums.
Drill cuttings will be staged on-site and disposed of at a later date after being analyzed for
appropriate parameters.
Well MW09 will be used as the injection well. Newly drilled piezometers, located downgradient
from well MW09, will be used both as monitoring points for the groundwater tracer study and the
bioremediation field test. The exact number and location of the piezometers may be changed
based on a groundwater elevation evaluation conducted during the initial phase of this study. At
this time, it is anticipated that six piez6meters will be located downgradient of well MW09 and
perpendicular to groundwater flow. Groundwater velocity will be estimated based on existing
data. The injection well and piezometers will be located at a distance equivalent to approximately
two weeks of groundwater travel time. This two-week travel time should be sufficient for the
microbes to degrade the constituents during the bioremediation field test.
It is recognized that MW09 may not be suitable as a monitoring well after its use in the
pilot study. However, it is believed that, upon the construction of the planned network of
compliance monitoring wells and through the use of other existing monitoring wells, MW09
will not be an essential element of the site monitoring program.
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January 19, 1994
Project Number: 2785
Page 12
After each piezometer is installed, the observed groundwater elevation will be compared to the
predicted elevation before installation. If a significant elevation difference exists, indicating that
the injected tracer would not be expected to reach the downgradient monitoring point, a new
location will be field selected and a new piezometer installed.
3.3.2 Methodology
Details of the field procedures for the tracer test are presented in Appendix A. Sodium bromide
and/or sodium iodide tracers will be used to trace groundwater-flow direction. The use of two
different tracer compounds may be needed to prevent confusion if it is necessary to conduct two
tracer tests. The tracer compounds will be added to the groundwater at concentrations higher
than the background concentrations measured during the site assessment. Five-gallon batches of
tracer solution will be added to the injection well for five consecutive days. The exact tracer
concentrations and volumes to be added will be calculated based on the estimated volume of
groundwater present in the zone between the well and piezometers. Beginning with the day when
tracer addition begins, downgradient monitoring points (piezometers) will be sampled and
analyzed daily for the tracer. Each tracer experiment will be discontinued 5 days after the tracer is
detected in the downgradient location.
3.3.3 Data Analysis and Reporting
A technical memorandum will be issued to summarize the results, conclusions, and
recommendations of the tracer study. The memorandum will include maps showing the locations
of piezometers and injection well and graphs of tracer added versus time and tracer concentration
in the downgradient location versus time for each piezometer.
3.4 Pilot-Scale Field Test
Results of the site assessment and characterization, optimization, and tracer studies will provide a
high level of confidence for defining the indigenous anaerobic microbial activity, metabolic
conditions required for anaerobic biodegradation, and area-specific groundwater flow regime.
After completing these preliminary studies, DERS will initiate an in-situ bioremediation pilot test
at the Upper Macon site. The objectives of this test are to deten:nine
• The feasibility of promoting the in-situ biological dechlorination of target contaminants
using indigenous microbes and anaerobic conditions.
• The biodegradation rates under enhanced field conditions .
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The results of the pilot test will be used to support the evaluation of bioremediation's effectiveness
and implementability for supplementing the site groundwater remedy. Further pilot-scale field
investigations may be necessary to support the full-scale design if the technology proves to be
applicable to site.
3.4.1 Study Area
The pilot test will be conducted in the same area as the tracer study. Based on the existing data,
the area in the vicinity of well MW09 has been selected as the study area. This location is known
to have elevated concentrations of the contaminants.
3.4.2 Methodology
Details for the pilot test methodology will be developed based on the results of the other
treatability evaluation activities. Briefly, the field test sequence will include preparing
amendments (identified in the optimization study) and dosing the upgradient injection well to
create favorable biodegradation conditions in the area-specific groundwater zone which can be
monitored at downgradient piezometers. Well dosing will occur continuously in the upgradient
well until conditions have been established in the test cell, as monitored at the downgradient
piezometers.
Groundwater samples will be collected bi-weekly in the first third of the pilot study, and monthly
thereafter from the downgradient observation piezometers during the test period and will be
analyzed for the following parameters:
• Constituents of concern;
• Metabolic end products (ethane, ethene, methane);
• Phosphorus;
• Alkalinity; and
• Hydrogen sulfide .
Field parameters (temperature, pH, Eh, and DO) will also be analyzed to ascertain crucial
microbial parameters. All samples will be analyzed following appropriate QA/QC procedures. A
summary of field parameters is provided in Table 3-1.
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3.4.3 Data Analysis and Reporting
January 19, 1994
Project Number: 2785
Page 14
After data has been accumulated and evaluated, DERS will issue a report documenting the
findings of the pilot study and providing recommendations for a future course of action.
Sufficient infonnation should be available to reasonably assess the site-specific potential of
bioremediation after completion of this pilot study. Any additional infonnation required for full-
scale design will be identified after this study is complete and will be delineated in the pilot study
report.
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4.0 SCHEDULE
January 19, 1994
Project Number: 2785
Page 15
The schedule, as illustrated in Figure 4-1, for the anaerobic bioremediation work plan commences
with the implementation of the site assessment and characterization and concludes with the
completion of the pilot test.
The total duration of the site assessment and characterization is four weeks. It is anticipated that
the site assessment and characterization will include two weeks to compile the results and prepare
a technical memorandum.
The tracer and optimization studies may commence at any time after the preliminary results of the
site assessment and characterization are available. The optimization and tracer studies must be
completed prior to field test start-up. The laboratory optimization study will require
approximately 12 weeks to complete. The total duration of the tracer study is anticipated to be 8
weeks, including new piezometer installations (2 weeks), tracer addition and testing (four weeks),
data analysis, and technical memorandum preparation.
The field test ( consisting of field testing and the tracer study) is anticipated to take a maximum of
3 6 weeks to complete. The actual field testing will require 12 to 20 weeks; however, this period
may need to be extended to ensure the accuracy of the results. The technical memorandum
documenting the results of the field test is anticipated to require four weeks to prepare following
the conclusion of the pilot field test. The remainder of the scheduled time is for analytical
turnaround and data reduction.
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5.0 REFERENCES
January 19, 1994
Project Number: 2785
Page 16
Beeman, R. E., et al. (in press). A Field Evaluation of In-Situ Microbial Reductive
Dehalogenation by the Biotransformalion of Chlorinated Ethylenes. To be presented at the
Second International Symposium on In-Situ and On-site Bioreclamation, April 5-8, 1993. San
Diego, California.
DiStefano, T. D., J.M. Gossett, and S. H. Zinder. 1991. "Reductive Dehalogenation of High
Concentrations of Tetrachloroethene to Ethene by an Anaerobic Enrichment Culture in the
Absence ofMethanogenesis." Applied and Environmental Microbiology 57:2287-2292.
Gibson, S. A., and G. W. Sewell. 1992. "Stimulation of Reductive Dechlorination of
Tetrachloroethene in Anaerobic Aquifer Microcosms by Addition of Short-chain Organic Acids or
Alcohols." Applied and Environmental Microbiology 5 8: 13 92-13 93.
Gossett, J.M., T. D. DiStefano, and S. H. Zinder. 1992. "The Role of Hydrogen in the
Biotransfonnation of Chlorinated Ethenes by an Anaerobic Mixed Culture-Implications for
Bioremediation." In Lesage, S. (ed.), In-Situ Bioremedialion Symposium '92. Niagara-on-the-
Lake, Ontario. pp. 124-149.
Lee, M. D., et al. 1988. "Biorestoration of Aquifers Contaminated with Organic Chemicals."
CRC Critical Reviews in Environmental Control, 18:29-89.
RMT, Inc. 1993. "Preliminary Design Report for the Macon/Dockery site."
1993. "Health and Safety Plan for the Macon/Dockery site."
1992. "Sampling and Analysis Plan for the Macon/Dockery site."
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TABLE l·l
SUM;\tARY Of SOURCE AREA GROUNDWATER PARAMETERS
(Jl,farch, 1993 Sampling;)
Par~mcr.cr
Total Dissolved Solids
Hardness as CnCO3
Total Organic Carbon as NPOC
Biochemical Oxygen Demand
Chemical o~-ygcn Demand
Sulfate
Sulfide
Dissolved Iron
Dissolved Manganese
Dissolved Copper
Mcthancb
Ethancb
Ethylcncb
Propancb
Tclr.ichlorocthc11c
Trichloroctl1cnc
I, 1-Dichlorocthcnc (DCEJ
1.2-Dichloroclhci,c (lot:il)
cis-1,2-DCE
tr:ins-1 ,2-DCE
Vin)·l chloride
Carbon tetrachloride
Methyl chloride
Chloroform
Chloromcthanc
MWO<i
48
9.9
0.81
<2
<5
<10
1.3
<0.100
<0.015
<0.020
0.0123
<0.0138
<0.0298
<0.0387
0.027
0.086
0.018
0.020
0.013
<0.010
<0.010
<0.010
<0.010
<0.010
<0.010
Macon Site
Upper
MW09
180
47
19
6
130
<10
1.3
1.300
1.7G
<0.020
0.523
<0.0133
O.SG4
<0.372
0.025, 0.031D
0.028, 0.0310
0.012, O.OlGDJ
0.034
0.055
<0.025
0.35E, 0.360
<0.025
0.004BJ
<O.OIO ppm
<0.025
Docl,ery Site
Lower Upper
MW13 MWIS
100 70
39 14
3.3 7.4
6 6
21 42
<10 <10
<1.0 <l.O
<0.100 <0.100
0.251 0.157
<0.020 <0.020
0.0123 <0.0141
<0.0130 <0.0133
<0.0281 <0.0287
<0.0365 <0.0374
0.0021 0.0-0071
0.026 0.004J, 0.005D1
0.037 0.52E, O.GKD
0.0441 0.0021
0.003 <0.050
<0.010 <0.050
<0.010 <0.010
<0.010 <0.050
<0.010 0.0051, O.OllDJ
<0,010 <0.010
<0.010 <0.0S0
Lower
MWIG
160
84
4.5
<2
20
19
1.3
<0.100
0.0894
<0.020
0.0lGS
<0.0135
<0.0291
<0.0378
<0.010
0.0051
0.024
<0.010
<0.010
<0.010
<0.010
<0.010
<0.010
<0.010
<0.010 L ____________________________ __J
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Results reported in parts per million
July, 1993 s.,mpling
Estimated concentration
Concentration exceeds Instrument Calibration Range
Results Crom diluted sample
Concentration is Below Detection Limits or Instrument Quantification Limit
Highlighted parameters are indicative or naturally-occurring microbial reductive dechlorination
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TABLE 3-1
PILOT STUDY ANALYTICAL
PARA.i'\-IETERS AND 1\-IETHODS
··•<in,f1H:Hfi;:\~~;paf"ain'iter•?''••·:•1•·_•• --~ i/HHLSu~~~ted:.Xha1·rH~l-•·-Nf e'fti6:d _.·!ili.l,
Organic Contaminants
Volatile Organics EPA Method 624
GenP.i"al Analyses
Total Or2anic Carbon EPA Method 415.1
Ch-emical Oxve:en Demand EPA Method 410.1
Ca,bonate Alkalinity EPA Method 310.1
Inor:!anic Nutrients
Ammonia-Nitroeen EPA Method 350.2
Kiddahl-Nitroeen EPA Method 3S1.3
Total Phosphorus EPA Method 36S.2
Final Metabolic End Products
Methane Gas Chromato2raphy
Ethane Gas Chromato2raphy
Ethene Gas Chromatography
J\,b i or Cations and Anions
Bromide, Total EPA Method 405 or IC
Iron, Dissolved EPA Method 236.1 or ICP
Iron. Total EPA Method 236.1 or ICP
Maenesium, Total EPA Method 242.1 or ICP
Potassium. Total EPA Method 2S8.1 or ICP 1',,lane;anese, Dissolved EPA Method 243.1 or ICP
Man2anese. Total EPA Method 243.1 or ICP
----- - - - -------· -- --
OV-4
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-$-[1datln4j1 ObHN<lllan Well
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UPON
30
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Houdon, fu,:u
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OV-J
TANK 9
PSP..I
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Proposed Monitoring Point Locofions
Upper Macon Aquifer Pilot Bioremedia!ion Study
Macon/Dockery Site, Richmond County, NC
I I TANK 5
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4
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I BlDG. ·2
\ \ \ \ \ '---
-----
Oil'IN: D[S.: PRo...t:CI NO..:
KPL
CHKO: APPO, 402550
COL COL 1------<----1 OGUJ,( NO.:
DAl[: R(Y.:
10/22/9J 1
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1.0 TRACER TEST
October 13, 1993
Project Number: 278S
Page I
The tracer test is designed to verify the direction of groundwater flow from the injection well
to the newly installed piezomcters chosen for the experiment. This test consists of the
following protocol:
• Injection Well
Five gallons of sodium bromide and/or sodium iodide solution will be surged into
upgradient injection well (MW09) in the morning for five consecutive days according
to the following protocol:
Unlock injection well to be used.
Decontaminate prior to introduction to the well and piezometers. Using
a dedicated surge block, clean the screen/open-hole interval of the well by
moving the surge block up and down several times. The surge block can be
constructed of readily available plumbing/hardware materials.
-Prepare the tracer solution in a decontaminated 5-gallon bucket by
dissolving a predetermined quantity of sodium bromide and/or sodium iodide in
5 gallons of potable water.
-Pour the tracer solution into the well. Wash the casing with a small
quantity of potable water.
-Surge the well with the surge block for approximately five minutes to
disperse the tracer solution adequately into the aquifer.
-Wash the casing with a small quantity of potable water.
The tracer concentration and, therefore, the quantity of sodium bromide and/or sodium iodide,
will be calculated based on its dilution in an estimated volume of water in the zone between the
injection well and the new piezometers. The new piezometers will be installed at a point
downgradient of the injection well so that solutions introduced to the aquifer will reach the
piezometers after approximately two weeks. The distance between the new piezometers and
the injection well will be calculated using the following equation:
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whore:
D -Diswice betwe.,n piezometers and injection well
K = Estimated hydraulic conductivity of the aquifer
1 m Estimated hydr•ulic gradient
n = Approximate porosity
I ~ Travel time (i.e., rwo w<lclcs)
October 13, 1993
Project !'lumber: 278S
Page 2
Once the piezometers are installed, the volume of water between the piezometers and injection
well can .be estimated using the following equation:
V = DbW
where:
V = Estimated volume of water between injection point (Well MW09) and
observation point (piezometars)
D = Distance between piezometers and injection well
b -Average saturated thickness
W = Width fraction to allow for dispersion/diffusion of slug
In calculating the total quantity of the tracer and/or substrate to be added throughout the study,
it is assu.med that the tracer/substrate added will be completely diluted in the estimated volume
of water between the injection well and the piezometers.
For the tracer test, a "target" tracer concentration for the piezometers equal to 10 times the
background concentration observed at that well will be used. For e,;ample, if bromide were
detected at the piezometers at a concentration of 3 parts per million (ppm), then the target
bromide concentration to be observed at the observation well after tracer solution injection at
the injection well would be 30 ppm. Therefore, the quantity of tracer compound to be added
for the entire test is defined by the following equation:
M = Targ~t concentntion (v + V)
where:
M -Mass of tracer to be addc>d
v = Volume of tracer solution to be added
V c Volume of water between piezometcrs and well
The trac,!r quantities and volumes to be used on a per injection basis are equal to the total to be
used for the entire test divided by the number of injections.
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• Piezometers
October 13, 1993
Project Number: 2735
Psg• J
For five days prior to the initiation of tracer injection, groundwater from the
pi~zometers will be sampled daily for analysis to establish baseline bromide and/or
iodide concentrations at the piezometer. Beginning with the first day that the tracer
injection is initiated, groundwater samples will be collected daily from each piezometer
ar.d analyzed for bromide and/or iodide. Efforts will be made to keep the time of day
in which injection of the tracer and well sampling are performed. uniform. Sampling
will be performed in accordance with the field sampling procedures previously
developed for the site. In general, sampling will occur according to the following
protocol:
-Collect groundwater sample using a dedicated Teflon® bailer.
Thoroughly decontaminate all dedicated sampling materials prior to use. Do not
purge the piezometers as this will disrupt natural hydrologic conditions (e.g.,
gradients) on which tracer test parameters were derived.
-Collect conductivity, dissolved oxygen, Eh, pH, and temperature field
measurements twice daily. Collect measurements in the morning prior to tracer
injection and in the afternoon during sampling.
-Fill appropriate bottle set for tracer analysis.
The test will be discontinued five days after the tracer is detected. To minimize the time lag
between receipt of analytical results and deciding when to end the tracer test, an accelerated
laboratory turnaround time for tracer analysis will be utilized.
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2.0 PILOT TEST (FORMATION FEEDJNG)
October 13, 1993
Project Numbor: 2785
Page 4
After completing the laboratory optimization and tracer study, a bioremediation pilot test will
be initiat,!d. The objectives of this test are to determine:
• The feasibility of promoting the in situ biological dechlorination of target contaminants
u:;ing indigenous microbes and anaerobic conditions; and
• Biodegradation rates under enhanced conditions in the field.
This test will consist of dosing the upgradient well with substrate and electron donor solutions
to drive the aquifer anaerobic and the monitoring for a variety of analytical parameters to
evaluate the presence of microbial dechlorination. The test includes the following:
• Irjection Well
A substrate solution will be injected into the injection well in the morning, three times
a week, throughout the length of the test according to the following procedure:
Unlock the wen to be used.
Using the surge block, clean the screen of the piezometer by moving the
surge block up and down several times.
-Mi:ic the substrate solution in a decontaminated 5-ga11on bucket using
predetermined quantities of amendments.
Pour the substrate solution into the well. Wash the casing with potable
water.
Surge the well with the surge block for 10 to 15 minutes to disperse the
substrate mi:icture into the aquifer.
Wash the casing with potable water.
• PZewmeters
Tne observation piezometers will be sampled for a variety of field and laboratory
analysis parameters according to the following protocol:
-Purge the piezometers of.one volume of water. Collect a groundwater
sample using a dedicated TEFLON bailer.
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October IJ, 1993
Project Number: 2785
Pago 5
-Collect conductivity, dissolved oxygen, Eh, pH, and temperature field measurements daily. Collect measurements prior to substrate injection and sampling. ·
-Fill the appropriate bottle for laboratory analysis according to the frequency established in the work plan.
-Field-filter the samples collected for soluble analytical parameters through 45-micron filter paper and a hand vacuum filtration assembly. Preserve the samples where applicable. Decontaminate the filtration assembly thoroughly between samples.
The types of materials to be included in the substrate mixture will be determined based on the
results c.f the optimization studies. The quantities to be used during the field test will also be
derived based on the results of the optimization study and the hydraulic conditions evaluated
during the tracer test.
Efforts will be made to keep the time of day in which the injection of the substrate and
sampling are performed uniform. The same dedicated equipment from the tracer test will be
used for surging and sampling throughout the field test. Analytical services will be provided
by a contract laboratory.