vvEPA
EPA 540/R-09/004
October 2009
Hydrogen Release Compound (HRCŪ) Barrier
Application at the North of Basin F Site,
Rocky Mountain Arsenal
Innovative Technology Evaluation Report
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EPA 540/R-09/004
October 2009
Hydrogen Release Compound (HRCŪ) Barrier
Application at the North of Basin F Site,
Rocky Mountain Arsenal
Innovative Technology Evaluation Report
Prepared for:
Randy Parker
National Risk Management Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH 45268
National Risk Management Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
11
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NOTICE
The information in this document has been funded by the U.S. Environmental Protection Agency
(EPA) under Contract No. 68-C-00-181 to Tetra Tech EM Inc. It has been subjected to the Agency's
peer and administrative reviews and has been approved for publication as an EPA document.
Mention of trade names or commercial products does not constitute an endorsement or
recommendation for use.
in
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FOREWORD
The U.S. Environmental Protection 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 nurture life. To meet this mandate, EPA's research program is
providing data and technical support for solving environmental problems today and building a science
knowledge base necessary to manage our ecological resources wisely, understand how pollutants
affect our health, and prevent or reduce environmental risks in the future.
The National Risk Management Research Laboratory is the Agency's center for investigation of
technological and management approaches for reducing risks from threats to human health and the
environment. The focus of the Laboratory's research program is on methods for the prevention and
control of pollution to air, land, water, and subsurface resources; protection of water quality in public
water systems; remediation of contaminated sites and groundwater; and prevention and control of
indoor air pollution. The goal of this research effort is to catalyze development and implementation
of innovative, cost-effective environmental technologies; develop scientific and engineering
information needed by EPA to support regulatory and policy decisions; and provide technical support
and information transfer to ensure effective implementation of environmental regulations and
strategies.
This publication has been produced as part of the Laboratory's strategic long-term research plan. It is
published and made available by EPA's Office of Research and Development to assist the user
community and to link researchers with their clients.
Sally C. Gutierrez, Director
National Risk Management Research Laboratory
IV
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ABSTRACT
This Innovative Technology Evaluation Report documents the results of a demonstration of the hydrogen
release compound (HRCŪ) barrier technology developed by Regenesis Bioremediation Products, Inc., of
San Clemente, California. HRCŪ is a proprietary, food-quality glycerol polylactate ester that slowly
releases lactic acid when injected into groundwater aquifers. The HRCŪ enhances natural anaerobic
degradation of organic contaminants in the groundwater. The technology was evaluated from February
2001 to October 2002 at the North of Basin F site at the Rocky Mountain Arsenal (RMA) in Commerce
City, Colorado. The demonstration evaluated the technology's ability to treat groundwater containing
contaminants generated during the processing of chemical warfare agents and during commercial
production of pesticides.
The technology evaluation was conducted in an alluvial, surficial aquifer consisting of an upper 1- to 3-
foot interval of well-graded sand/gravel and a lower 7- to 8-foot interval of unconsolidated sand to
poorly cemented sandstone; the aquifer overlays the claystone of the Denver Formation. A 50-foot by
30-foot L-shaped permeable barrier of HRCŪ was installed; each leg of the barrier consisted of three
staggered rows of injection points on 6-foot centers. HRCŪ was injected from the bottom up using
direct-push methods at a dose rate of about 10 pounds per foot over a 10-foot interval (from about 44 to
54 feet below ground surface). A total of 4,200 pounds of HRCŪ was injected in 42 points.
Groundwater samples were collected from an array of monitoring wells to evaluate the technology's
performance. The wells were located upgradient, within, and downgradient from the HRCŪ barrier.
The primary objective of the technology evaluation was to determine the ability of the technology to
significantly reduce the primary contaminants of concern (COC) in the North of Basin F plume study
area. The primary COCs consisted of di-isopropylmethylphosphonate (DIMP), chlorophenylmethyl
sulfide, chlorophenylmethyl sulfone, dieldrin, dicyclopentadiene (DCPD), chloroform, methylene
chloride, and tetrachloroethene (PCE). Benzene, trichloroethene (TCE), l,2-dibromo-3-chloropropane,
and n-nitroso-dimethylamine were evaluated as secondary COCs. Results of the evaluation showed
decreasing trends for the following COCs: PCE, TCE, DIMP, DCPD, and benzene. Percent reductions
for these COCs were generally in the 50 to 80 percent range at multiple downgradient wells, although
higher percent reductions were observed for PCE and DCPD (90 to 95 percent). Downgradient
concentrations of PCE, DCPD, and benzene were also reduced over the course of the evaluation to below
applicable site-specific remediation goals.
An economic analysis of the HRCŪ technology indicated that costs can vary considerably and are based
on several factors, including the type and scale of the application, contaminant types and levels,
regulatory criteria, and various site-specific factors. The estimated cost for the scenario in the economic
analysis section of this report, which incorporates actual costs for 1 year of treatment under conditions
similar to those encountered at RMA, was approximately $0.55 per gallon of treated water. Over a
longer period of time, this unit cost would likely be significantly reduced.
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CONTENTS
Section Page
ACRONYMS AND ABBREVIATIONS xi
CONVERSION FACTORS xiii
ACKNOWLEDGMENTS xiv
EXECUTIVE SUMMARY ES-1
1.0 INTRODUCTION 1
1.1 PURPOSE AND ORGANIZATION OF THE ITER 1
1.2 DESCRIPTION OF THE DEMONSTRATION SITE 1
1.2.1 Site Location and History 3
1.2.2 Site Geology/Hydrogeology 3
1.2.3 Existing Remediation Systems and Containment Concentrations 3
1.3 DESCRIPTION OF THE HRCŪ TECHNOLOGY 4
1.3.1 Principles of the Technology 4
1.3.2 Previous Demonstrations and Treatability Studies 8
1.4 FIELD CONSTRUCTION ACTIVITIES FOR THE EVALUATION 8
1.4.1 Installation of Groundwater Monitoring Wells 8
1.4.2 Construction of the HRCŪ Permeable Barrier 10
1.5 EVALUATION OBJECTIVES 10
1.6 KEY CONTACTS 12
2.0 TREATMENT EFFECTIVENESS 13
2.1 EVALUATION APPROACH AND METHODS 13
2.1.1 Experimental Design 13
VI
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CONTENTS (Continued)
Section
2.1.2 Sampling Frequency 13
2.1.3 Sampling and Analytical Methods 13
2.2 EVALUATION RESULTS 14
2.2.1 Impact of HRCŪ Injection on Groundwater Chemistry 14
2.2.2 COC Degradation Trends 20
2.2.3 Quality Control Program 39
2.3 EVALUATION OF RESULTS AGAINST THE OBJECTIVES 40
2.3.1 Objective PI 40
2.3.2 Objective SI 40
2.3.3 Objective S2 41
2.3.4 Objective S3 42
2.3.5 Objective S4 42
3.0 ECONOMIC ANALYSIS 43
3.1 GENERAL ISSUES AND ASSUMPTIONS 43
3. .1 Type and Scale of Application 43
3. .2 Contaminant Types and Levels 43
3. .3 Regulatory Criteria 44
3. .4 Site-Specific Features 44
3. .5 General Assumptions 44
3.2 HRCŪ REMEDIAL APPLICATION 45
3.2.1 Site Preparation Costs 45
3.2.2 Permitting and Regulatory Costs 50
3.2.3 Mobilization and Startup Costs 50
3.2.4 Equipment Costs 50
3.2.5 Labor Costs 51
3.2.6 Supply Costs 51
3.2.7 Utility Costs 51
3.2.8 Effluent Treatment and Disposal Costs 51
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CONTENTS (Continued)
Section Page
3.2.9 Residual Waste Shipping and Handling Costs 51
3.2.10 Analytical Services Costs 52
3.2.11 Equipment Maintenance Costs 52
3.2.12 Site Demobilization Costs 52
3.3 CONCLUSIONS OF THE ECONOMIC ANALYSIS 52
4.0 TECHNOLOGY APPLICATIONS ANALYSIS 54
4.1 FACTORS AFFECTING PERFORMANCE 54
4.1.1 Applicable Wastes 54
4.1.2 Hydrogeologic Characteristics 56
4.1.3 Operating Parameters 59
4.1.4 Maintenance Requirements 61
4.2 SITE CHARACTERISTICS AND SUPPORT REQUIREMENTS 61
4.2.1 Site Access, Area, and Preparation Requirements 61
4.2.2 Climate Requirements 62
4.2.3 Utility and Peripheral Supply Requirements 62
4.2.4 Required Support Systems 62
4.2.5 Personnel Requirements 63
4.3 MATERIAL HANDLING REQUIREMENTS 63
4.4 TECHNOLOGY LIMITATIONS 63
4.5 POTENTIAL REGULATORY REQUIREMENTS 64
4.5.1 Comprehensive Environmental Response, Compensation, and Liability Act.... 66
4.5.2 Resource Conservation and Recovery Act 67
4.5.3 Clean Water Act 68
4.5.4 Safe Drinking Water Act 69
4.5.5 Clean Air Act 69
4.5.6 Mixed Waste Regulations 69
4.5.7 Occupational Safety and Health Act (OSHA) 70
4.6 STATE AND COMMUNITY ACCEPTANCE 70
5.0 TECHNOLOGY STATUS 71
REFERENCES 73
Vlll
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CONTENTS (Continued)
Appendix
A VENDOR'S CLAIMS FOR THE TECHNOLOGY
IX
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LIST OF FIGURES
Figure Page
1-1 LOCATION MAP 2
1-2 BREAKDOWN OF LACTIC ACID AND RELEASE OF HYDROGEN 7
1-3 LOCATION OF MONITORING AND BARRIER INJECTION POINTS 9
2-1 TIME-SERIES PLOT FOR LACTIC ACID 16
2-2 TIME-SERIES PLOT FOR PROPIONIC ACID 17
2-3 TIME-SERIES PLOT FOR BUTYRIC ACID 18
2-4 TIME-SERIES PLOT FOR ACETIC ACID 19
2-5 TIME-SERIES PLOT FOR OXIDATION REDUCTION POTENTIAL 21
2-6 TIME-SERIES PLOT FOR pH 22
2-7 TIME-SERIES PLOT FOR IRON 23
2-8 TIME-SERIES PLOT FOR SULFATE 24
2-9 TIME-SERIES PLOT FOR DI-ISOPROPYLMETHYLPHOSPHONATE 26
2-10 TIME-SERIES PLOT FOR CHLOROPHENYLMETHYL SULFIDE 27
2-11 TIME-SERIES PLOT FOR CHLOROPHENYLMETHYL SULFONE 28
2-12 TIME-SERIES PLOT FOR DIELDRIN 29
2-13 TIME-SERIES PLOT FOR DICYCLOPENTADIENE 30
2-14 TIME-SERIES PLOT FOR BENZENE 31
2-15 TIME-SERIES PLOT FOR CHLOROFORM 32
2-16 TIME-SERIES PLOT FOR METHYLENE CHLORIDE 33
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LIST OF FIGURES (Continued)
Figure Page
2-17 TIME-SERIES PLOT FOR TETRACHLOROETHENE 34
2-18 TIME-SERIES PLOT FOR TRICHLOROETHENE 35
2-19 TIME-SERIES PLOT FOR DICHLOROETHENE 36
3-1 HRCŪ ESTIMATED COST BREAKDOWN 53
LIST OF TABLES
Table Page
1 -1 HISTORICAL ANALYTICAL RESULTS, BASIN A NECK SYSTEM INFLUENT 5
1 -2 CONTAMINANTS OF CONCERN AND GROUND WATER REMEDIATION GOALS 11
2-1 ANALYTICAL METHODS 15
2-2 CONTAMINANTS OF CONCERN AND AVERAGE BASELINE
CONCENTRATIONS 25
3-1 AQUIFER CHARACTERISTICS 46
3-2 INITIAL CONTAMINANT CONCENTRATIONS 47
3-3 GEOCHEMICAL PARAMETERS 47
3-4 ESTIMATED COSTS BY CATEGORY 48
4-1 SUMMARY OF TREATABLE CONTAMINANTS ACCORDING TO REGENESIS 55
4-2 SUMMARY OF ENVIRONMENTAL REGULATIONS 65
XI
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ACRONYMS AND ABBREVIATIONS
AEA Atomic Energy Commission
APC Applied Power Concepts, Inc.
ARAR Applicable or relevant and appropriate requirement
bgs Below ground surface
CAA Clean Air Act
CDPHE Colorado Department of Public Health and Environment
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act
cfu/mL Colony forming units per milliliter
COC Contaminant of concern
CPMS Chlorophenylmethyl sulfide
CPMSO2 Chlorophenylmethyl sulfone
CWA Clean Water Act
DCE Dichloroethene
DCPD Dicyclopentadiene
DIMP Di-isopropylmethylphosphonate
DNAPL Dense nonaqueous-phase liquid
DO Dissolved oxygen
EPA U.S. Environmental Protection Agency
FDEP Florida Department of Environmental Protection
ft/day Feet per day
GAC Granular activated carbon
HRCŪ Hydrogen release compound
IDW Investigation-derived waste
IP HRCŪ injection points
ITER Innovative Technology Evaluation Report
LCS/LCSD Laboratory control sample/laboratory control sample duplicate
L/min Liters per minute
ug/L Micrograms per liter
umol Micromole
mg/L Milligrams per liter
MS/MSD Matrix spike/matrix spike duplicate
mV Millivolts
NAPL Nonaqueous-phase liquid
NJDEP New Jersey Department of Environmental Protection
NPDES National Pollutant Discharge Elimination System
NRC Nuclear Regulatory Commission
NRMRL National Risk Management Research Laboratory
ORP Oxidation-reduction potential
OSHA Occupational Safety and Health Administration
OSWER Office of Solid Waste and Emergency Response
PCE Tetrachloroethene
POTW Publicly owned treatment works
QAPP Quality assurance project plan
xn
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ACRONYMS AND ABBREVIATIONS (Continued)
QC Quality control
RCRA Resource Conservation and Recovery Act
Regenesis Regenesis Bioremediation Products, Inc.
RMA Rocky Mountain Arsenal
ROD Record of Decision
RVO Remediation Venture Office
SDWA Safe Drinking Water Act
SITE Superfund Innovative Technology Evaluation
SOP Standard operating procedure
SVOC Semivolatile organic compound
TCE Trichloroethene
TER Technology Evaluation Report
Tetra Tech Tetra Tech EM Inc.
UIC Underground injection control
VOC Volatile organic compound
Xlll
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CONVERSION FACTORS
To Convert From: To:
Multiply By:
Length:
Area:
Volume:
inch
foot
mile
square foot
acre
gallon
cubic foot
cubic foot
cubic foot
centimeter
meter
kilometer
square meter
square meter
liter
cubic meter
gallon
cubic centimeter
2.54
0.305
1.61
0.0929
4,047
3.78
0.0283
7.48
28,317
Mass:
pound
kilogram
0.454
Temperature:
(Fahrenheit - 32) °Celsius
0.556
Time
days
minutes
1440
xiv
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ACKNOWLEDGMENTS
This report was prepared for the U.S. Environmental Protection Agency (EPA) Superfund Innovative
Technology Evaluation (SITE) Program by Tetra Tech EM Inc. under the direction and coordination of
Mr. Paul DePercin of the National Risk Management Research Laboratory (NRMRL) in Cincinnati,
Ohio.
The HRCŪ technology evaluation was a cooperative effort that involved the following personnel from the
EPA SITE Program, EPA Region VIII, Colorado Department of Public Health and the Environment
(CDPHE), Remediation Venture Office (RVO), U.S. Fish and Wildlife Service (USFWS), and the U.S.
Army, Rocky Mountain Arsenal (RMA):
Mr. Randy Parker EPA, NRMRL, SITE Program Director
Mr. Terrence Lyons EPA, NRMRL, Task Order Manager
Mr. Scott Jacobs EPA, NRMRL, Quality Assurance Manager
Mr. Larry Kimmel EPA Region VIII, Federal Facilities
Mr. Ed LaRock CDPHE
Mr. Anthony LaChance RVO, Remedial Project Manager
Mr. Stephen Smith RVO, USFWS
Mr. Stan Lynn Tetra Tech
Mr. Tom James U.S. Army, RMA
xv
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EXECUTIVE SUMMARY
This Innovative Technology Evaluation Report documents the results of a evaluation of the hydrogen
release compound (HRCŪ) barrier technology developed by Regenesis Bioremediation Products, Inc., of
San Clemente, California. HRCŪ is a proprietary, food-quality glycerol polylactate ester that slowly
releases lactic acid when injected into groundwater aquifers. The HRCŪ enhances natural anaerobic
degradation of organic contaminants in the groundwater. Other microorganisms use the controlled slow
production of hydrogen to enhance their capability of reductive dechlorination, which is recognized as
one of the primary attenuation mechanisms by which groundwater contaminated with chlorinated solvents
can be remediated.
The technology was evaluated from February 2001 to October 2002 at the North of Basin F site at the
Rocky Mountain Arsenal (RMA) in Commerce City, Colorado. The demonstration evaluated the
technology's ability to treat groundwater containing contaminants generated during the processing of
chemical warfare agents and during commercial production of pesticides. The primary contaminants in
groundwater at the North of Basin F site consisted of di-isopropylmethylphosphonate (DIMP),
chlorophenylmethyl sulfide, chlorophenylmethyl sulfone, dieldrin, dicyclopentadiene (DCPD),
chloroform, methylene chloride, tetrachloroethene (PCE), benzene, trichloroethene (TCE), 1,2-dibromo-
3-chloropropane, and n-nitroso-dimethylamine.
The primary objective for the evaluation was to determine the technology's ability to significantly reduce
the concentrations of each of the contaminants of concern (COC) in the North of Basin F plume.
Secondary objectives included (1) evaluating the technology's ability to achieve site-specific remediation
goals, and (2) monitoring time-plots of the concentrations of treatment-derived products and parameters
that might indicate anaerobic conditions.
The statistical evaluation of the analytical data collected from downgradient wells during the evaluation
found decreasing concentrations for the following COCs as a result of HRCŪ injection: PCE, TCE,
DIMP, DCPD, and benzene. Percent reductions for TCE, DIMP, and benzene were between 50 and 80
percent at multiple downgradient wells, while percent reductions for PCE and DCPD were higher at 90 to
95 percent. Analytical data for the remaining COCs did not show any well-defined or consistent
decreasing trends, suggesting that degradation of the remaining COCs was not accelerated by injection of
HRCŪ. Downgradient concentrations of PCE, DCPD, and benzene were consistently reduced to below
applicable remediation goals for the site.
Several other parameters, including volatile fatty acids, competing electron acceptors, and degradation
by-products, were evaluated in groundwater samples collected from downgradient wells to determine if
anaerobic conditions were sustained throughout the evaluation period. Analytical data indicated that
initial aquifer conditions were only mildly aerobic; however, a high dose of HRCŪ was required to
overcome competing electron acceptors, including iron and sulfate. Iron concentrations reached
maximum levels about 4 to 5 months following HRCŪ injection, and then declined gradually at most
wells. Sulfate concentrations fell from an average baseline concentration of 550 milligrams per liter
(mg/L) to less than 100 mg/L. In spite of the high hydrogen demand presented by the competing electron
acceptors, sufficient volatile fatty acids (lactic, propionic, butyric, and acetic acid, which are the hydrogen
sources), remained after 18 months following HRCŪ injection. Oxidation-reduction potential levels
ranged from -50 to -300 millivolts, and groundwater pH was reduced due to the release of the volatile
fatty acids, which indicates that anaerobic conditions were sustained and dechlorination continued
throughout the evaluation period.
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Analytical data from several wells showed a direct correlation between increasing concentrations of cis-
1,2-dichloroethene, which is a daughter product from the dechlorination of TCE, and decreasing
concentrations of TCE. However, further degradation of cis-l,2-DCE to vinyl chloride and ethene was
not observed.
An economic analysis of the HRCŪ technology was conducted for the barrier-based application
demonstrated at the RMA North of Basin F site. The cost estimate was primarily based on the
assumptions and unit costs provided by Regenesis, as well as information obtained during the SITE
technology evaluation. The cost estimate was based on actual costs experienced at RMA for 1 year of
application. The overall cost for lyear of treatment and monitoring was estimated to be $302,360, or
$0.55 per gallon of water treated, based on the estimated groundwater flow velocity for the aquifer.
However, most of the costs during the first year are one-time expenses, and the frequency of monitoring
would likely decrease in subsequent years, which would lower the costs proportionately if treatment was
extended beyond 1 year.
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1.0 INTRODUCTION
The Hydrogen Release Compound (HRCŪ) bioremediation technology developed by Regenesis
Bioremediation Products, Inc. (Regenesis), of San Clemente, California is designed to enhance
natural anaerobic degradation of organic contaminants in groundwater aquifers. A barrier
application of this technology was evaluated during a demonstration at the North of Basin F site
on the Rocky Mountain Arsenal (RMA) in Commerce City, Colorado. The evaluation was
conducted by the U.S. Environmental Protection Agency's (EPA) Superfund Innovative
Technology Evaluation (SITE) Program in cooperation with EPA Region VIII, the Colorado
Department of Public Health and Environment (CDPHE), and the Remediation Venture Office
(RVO) at RMA, which is staffed by representatives from the U.S. Army, Shell Oil Company, and
the U.S. Fish and Wildlife Service.
The technology evaluation occurred from February 2001 to October 2002. The technology
evaluated the ability of an HRCŪ barrier to treat groundwater containing contaminants generated
during the processing of chemical warfare agents by the government and during commercial
production of pesticides. This Innovative Technology Evaluation Report (ITER) summarizes the
results of that evaluation and provides other pertinent technical and cost information for potential
users of the technology. A separate Technology Evaluation Report (TER) provides detailed
information regarding the evaluation, including all data and associated statistical evaluations. For
additional information about the technology, the evaluation site, and the SITE Program; refer to
key contacts listed at the end of this section.
1 1 PURPOSE AND ORGANIZATION OF THE ITER
Information presented in the ITER is intended to assist decision-makers in evaluating specific
technologies for treatment of contaminated media. The ITER represents a critical step in the
development and commercialization of a treatment technology. The report discusses the
effectiveness and applicability of the technology and analyzes costs associated with its
application. The technology's effectiveness is evaluated based on data collected during the
evaluation. The applicability of the technology is discussed in terms of waste and site
characteristics that could affect technology performance, material handling requirements,
technology limitations, and other factors.
The purpose of this ITER is to present information that will assist decision-makers in evaluating
the HRCŪ technology for application to a particular site cleanup. This report provides
background information and introduces the HRCŪ bioremediation technology (Section 1.0),
analyzes the technology's effectiveness in treating contaminated groundwater at the RMA North
of Basin F site (Section 2.0), analyzes the economics of using the HRCŪ technology to treat
contaminated groundwater (Section 3.0), analyzes the technology's applications (Section 4.0),
summarizes the technology's status (Section 5.0), and presents a list of references used to prepare
the ITER. Vendor's claims for the HRCŪ technology are presented in Appendix A.
1.2 DESCRIPTION OF THE EVALUATION SITE
This section provides background information on the RMA and describes the North of Basin F
site at RMA. Figure 1-1 shows the location of this site and the surrounding features at RMA.
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1.2.1 Site Location and History
RMA occupies more than 17,000 acres (approximately 27 square miles) in southern Adams
County, Colorado. It is located approximately 10 miles northeast of downtown Denver,
Colorado.
The U.S. Government purchased the property in 1942 for use in World War II to manufacture and
assemble chemical warfare materials, such as mustard and lewisite, and incendiary munitions.
The nerve agent GB (isopropyl methylphosphonofluoridate) was produced during the 1950s. The
facility was also used for chemical warfare materials destruction during the 1950s and 1960s. In
addition to these military activities, major portions of the facility were leased to private industry,
primarily for pesticide manufacturing. Pesticides were produced from 1947 to 1982 while
portions of the arsenal were leased to Shell Oil Company.
During the 1940s and 1950s, the North Plants Area and the South Plants Area were accumulation
areas for aqueous industrial wastes. These wastes were typically discharged into several unlined
evaporation ponds. During the mid-1950s, groundwater contamination was suspected when
minor crop damage occurred on land located north and northwest of the RMA. The discovery of
this contamination led to the placement of an asphalt liner in Basin F. During this time, aqueous
wastes from Basin A and aqueous wastes produced thereafter were transferred directly to Basin F.
Figure 1-1 shows the location of these features at RMA, and highlights the location of the
evaluation site, which is located just north of
Basin F.
1.2.2 Site Geology/Hydrogeology
The geological and hydrostratigraphic units of interest at RMA include surficial, unconsolidated
alluvial and eolian sediments, collectively referred to as the alluvium. The alluvium in the area
north of Basin F is approximately 40 to 50 feet thick. The material consists primarily of sand and
silt with minor amounts of gravel and clay. The bedrock underlying the alluvium is the Denver
Formation, which consists of sandstones, siltstones, lignites, and claystones (EPA and U.S. Army
2000).
The North of Basin F site is located within an alluvial paleochannel, surficial aquifer consisting of
an upper 1 to 3 foot interval of well-graded sand/gravel and a lower 7 to 8 foot interval of
unconsolidated sand to poorly cemented sandstone; the aquifer overlays the claystone of the
Denver Formation. Groundwater in the area of Basin F generally flows north-northeast to east
(EPA and U.S. Army 2000). The hydraulic gradient and conductivity are on the order of 0.001
foot per foot and 250 feet per day (ft/day), respectively (Foster Wheeler Environmental
Corporation 1999).
1.2.3 Existing Remediation Systems and Contaminant Concentrations
Investigations evaluating the presence or absence of contamination in the flora and fauna at the
RMA have been conducted since the early 1950s (EPA and U.S. Army 2000). These
investigations were initiated as a result of observations of wildlife mortality and agricultural
damage. In 1974, CDPHE detected di-isopropylmethylphosphonate (DIMP) in the groundwater
north of RMA (EPA and U.S. Army 2000).
Additional investigations were completed by the U.S. Army Toxic Hazardous Materials Agency
in the 1970s and 1980s (EPA and U.S. Army 2000). Results of these investigations indicated that
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contamination exists primarily in the alluvial sediments and groundwater. Minor amounts of
contamination were observed in the Denver Formation.
The RMA site selected for the HRCŪ evaluation program is located just north of Basin F.
Aqueous industrial wastes containing various chemical warfare agents and pesticides were
discharged into Basin F at RMA and resulted in groundwater contamination at this site. As a
result, a pump-and-treat system was installed north of Basin F to remediate contaminated
groundwater. The extraction wells for the pump-and-treat system are located within and along
the boundary of RMA. The pump-and-treat system handled over 1 billion gallons of water in
1996 (EPA 1999).
Groundwater is extracted from Well 23311 at the North of Basin F site (EPA 1999). The
groundwater is pumped to the Basin A Neck System water treatment plant, located approximately
1.7 miles from Basin F, where it is treated through the use of granular activated carbon (GAC)
and an air stripper prior to injection back into the subsurface. The influent to the Basin A Neck
System water treatment plant is analyzed on a periodic basis; historical results of the analyses of
organic contaminants are presented in Table 1-1.
1.3 DESCRIPTION OF THE HRCŪ TECHNOLOGY
This section describes the Regenesis HRCŪ technology, as well as the site-specific design that
was implemented for the evaluation at the RMA North of Basin F site.
1.3.1 Principles of the Technology
HRCŪ is a proprietary, food-quality polylactate ester used to enhance in situ biodegradation rates
by slowly releasing lactic acid into the subsurface. The lactic acid is metabolized by naturally
occurring microorganisms, thereby creating anaerobic aquifer conditions and the production of
hydrogen. The microorganisms use the hydrogen to enhance their anaerobic degradation of
organic contaminants through reductive dechlorination of chlorinated organic contaminants in
groundwater. Reductive dechlorination results in the step-by-step biological degradation of
chlorinated contaminants. Figure 1-2 illustrates these chemical processes using tetrachloroethene
(PCE) as an example of a chlorinated organic compound that is reductively dechlorinated as
hydrogen is released from the anaerobic degradation of lactic acid. According to Regenesis,
HRCŪ can be used to degrade a range of chlorinated and other oxidized organic compounds,
including: chlorinated degreasing solvents (PCE, trichloroethene [TCE], trichloroethane, and their
breakdown products), carbon tetrachloride, chloroform, methylene chloride, certain pesticides
and herbicides, perchlorate, nitrate, nitroaromatic explosives and dyes, and chlorofluorocarbons
(Regenesis 2000).
HRCŪ is supplied as a viscous (20,000 centipoise), honey-like mixture of tripolylactate and
glycerol that can be directly injected into contaminated groundwater and saturated soils. HRCŪ is
specifically designed to slowly release lactic acid when it contacts water. For the HRCŪ process
to function efficiently, however, microbial colonies must be present in the soil that (1) are
suitable to perform the remediation, and (2) respond to an increase in both the biochemical energy
and the hydrogen generated from HRC Ū (Applied Power Concepts, Inc. [APC] 2000).
-------
Table 1-1
Historical Analytical Results, Basin A Neck System Influent
Parameter
Atrazine
Benzene
Chloroform
Di-isopropyl methyl
phosphonate
Chlorophenylmethyl
sulfide
Chlorophenylmethyl
sulfone
Dibromochloro-
propane
Dicyclopentadiene
Dieldrin
Year
1996 - 1999
1996 - 1999
1996 - 2000
1996 - 1999
1996 - 1999
1996 - 1999
1996 - 2000
1996 - 2000
1996 - 1999
Range of
Concentration
micrograms per
liter (jig/L)
< 0.346 -22.5
< 3.08 -< 500
590 - 18900
490 - 1000
68.6-230
86.3-380
< 44 - < 0.27
130 - 1000
(estimated)
< 10 -0.025
Average
Concentration
jig/L
22.5
10
10209
837
152
225
4
256
1.5
Trends
No Trend
No trend
Decreasing
Decreasing
Decreasing
Decreasing
No trend
No trend, but
one
anomalous
high
No trend
Comments
Detected in
one of 32
samples
Not detected
when
detection
limits greater
than 50 ug/L
Detected in 29
of 29 samples
Detected in 23
of 23 samples
Detected in 28
of 28 samples
Detected in 28
of 28 samples
Detected in 6
of 23 samples
Detected in 36
of 36 samples
Detected in 14
of 30 samples
-------
Table 1-1 (continued)
Historical Analytical Results, Basin A Neck System Influent
Parameter
Methylene chloride
Trichloroethene
Tetrachloroethene
N-Nitrosodimethyl-
amine
Year
1996 - 2000
1996 - 2000
1996 - 2000
1996 - 2000
Range of
Concentration
Jig/L
< 3.28 -< 500
40.8-93
50 - 200
0.89 -< 10
Average
Concentration
jig/L
49
62
140
2.2
Trends
No trend
Increasing
Decreasing
No trend
Comments
Detected in 14
of 29 samples
Detected in 29
of 29 samples
Detected in 29
of 29 samples
Detected in 15
of 20 samples
-------
FIGURE 1-2
BREAKDOWN OF LACTIC ACID AM) .EELEASE OF HYDROGEN
Figure 1-2
-------
HRCŪ is typically applied using direct injection techniques. This process enables HRCŪ to be
pressure- injected into the zone of contamination and forced into the aquifer. Once in the
subsurface, HRCŪ will reside within the soil matrix and continue to provide a slow release of
lactic acid for up to 18 months. The HRCŪ is typically injected into the aquifer matrix in a series
of closely spaced rows to form a "permeable barrier" or "treatment wall" that cuts off an
advancing contaminant plume.
1.3.2 Previous Evaluations and Treatability Studies
An initial SITE Program evaluation, which was conducted from 1990 to 1993, involved a
sequential anaerobic/aerobic biodegradation bench-scale test using various electron donors.
Results of the bench-scale test indicated that lactic acid (HRCŪ as lactate source) was the most
effective electron donor. The SITE Program conducted a second evaluation that involved
isolating a small circulating groundwater cell, using a series of extraction and injection wells, in
the central area of a chlorinated solvent plume at a site in Watertown, Massachusetts from 1997
to 1998. Results of the test indicated a 97 percent reduction in total mass for chlorinated volatile
organic compounds (VOC) in groundwater using HRCŪ.
The RMA site that was selected for the HRCŪ evaluation program is located just north of the
source zone, referred to as Basin F (see Figure 1-1). Aqueous industrial wastes consisting of
various chemical warfare agents were discharged into Basin F at RMA and resulted in
groundwater contamination. To investigate alternatives to the existing pump-and-treat system for
the remediation of contaminated groundwater at this site, a series of bench-scale studies involving
three in situ treatment technologies was proposed. The three alternatives included HRCŪ,
Oxygen Release Compound, and Zero Valent Iron. Following the bench-scale studies, an in situ
field evaluation of the HRCŪ technology was proposed at the North of Basin F site. Regenesis
was contracted to initiate the evaluation at the North of Basin F site.
Prior to the evaluation, APC conducted a series of treatability studies for Regenesis to determine
the suitability of natural microbial populations to (1) remediate contaminated groundwater at the
RMA North of Basin F site, and (2) understand how the colonies would respond to an increase of
biochemical energy and hydrogen generated from HRCŪ. Results of the treatability studies
indicated that the soil at RMA contains appropriate microbial colonies for application of HRCŪ
(APC 2000).
1.4 FIELD CONSTRUCTION ACTIVITIES FOR THE EVALUATION
Field construction activities for the evaluation at the RMA North of Basin F site included the
installation of a series of monitoring wells upgradient and downgradient of the intended HRCŪ
barrier location, followed by the construction of the barrier itself. Figure 1-3 is a schematic
depicting the barrier and monitoring well layout.
1.4.1 Installation of Groundwater Monitoring Wells
A location along the alluvial aquifer was identified as the location for installation of the HRCŪ
barrier wall for the evaluation. To characterize the contaminated groundwater upgradient and
downgradient from the barrier wall, 12 monitoring wells were installed upgradient and
downgradient from the planned barrier location. One set of downgradient wells was installed
along the central axis of the barrier parallel to the
-------
RANGE OF CROUNDWATER
FLOW D)REGION
23254^
23006
23532
A
23311
23237
Note: Well color codings arc used in time plots to denote locations
relative to uroundw utcr flow and Ihc harrier:
Him- tor background (upgnidicnt)
Red tor near (harrier) downyradicnt
Black KM mid downgrudicnl
tut t'.ir downgradienl
LEQfUP
+ MOM TORI 1C WELL LOCATION
A
EXISTING EXFWCTION WELL
(NOT CURRENTLY OPERAINC)
IMMOQEN RELEASE COMPOUND (HRC)
INJECTION POIKT LOCATION
THT SAMPLE LOCADON
3258
23264
Z3259
23263
1B 17 16
6 S 4
HRC Barrier
'- Y 2 1
HKC UtUONSlKAIIQN
ROCKY MOUNTAIN ARSENAL
FIGURE 1-3
LOCATION Or MON TORINC AND
BARRIER INXCTION POINTS
Tŧlra TŦt* EM In a
Figure 1-3
assumed easterly groundwater flow direction (wells 23255 through 23259). Existing well 23006
served as the upgradient, on-axis well. For groundwater potentially flowing north-northeast, a
similar axial arrangement was used with well 23265 serving as the upgradient, on-axis well. The
series of wells oriented along the north-northeast groundwater flow axis, including 23263, 23264,
23258, and 23262; served as the downgradient wells along this axis of the barrier. Figure 1-3
shows the locations of the monitoring wells in relation to the HRCŪ barrier.
The wells were constructed of 2-inch-diameter, flush-threaded, Schedule 40 polyvinyl chloride
pipe and were screened at the base of the alluvial channel (approximately a 10-foot interval from
about 43 to 53 feet below ground surface [bgs]). A sand pack with a 10/20 nominal sieve size
was installed around and up to a minimum of 2 feet above the top of the screened interval, and a
bentonite seal of minimum 2-foot thickness was installed above the sand pack. Wells were
located from 45 feet upgradient to about 30 feet downgradient from the 12-foot-wide barrier.
-------
1.4.2 Construction of the HRC Permeable Barrier
Based on historical groundwater elevation data, groundwater flow directions at this site vary from
north-northeast to east, depending on the time of year and other factors. A tracer study conducted
at the site prior to the evaluation indicated that the primary groundwater velocity vector was
northeast at the time of the study.
Due to the variability of the groundwater flow direction at this site, the barrier was installed in an
"L" shape to ensure that groundwater flowing to any of the downgradient wells would pass
through the treatment wall. To satisfy this arrangement, a 50-foot by 30-foot L-shaped HRCŪ
permeable barrier was installed across the alluvial aquifer north of Basin F, as shown in Figure 1-
3. HRCŪ was injected from the bottom up into each direct-push borehole at a dose rate of about
10 pounds per foot over a 10-foot interval from about 44 to 54 feet bgs. A total of about 4,200
pounds of HRCŪ was injected in these 42 points.
The constructed HRCŪ barrier was 12 feet in width with a 6-foot spacing between each of three
rows of injection points. Injection of the HRCŪ barrier took about 1 week. The injections started
at the upgradient row and progressed to the downgradient row so that a complete treatment effect
would be observed in the first element of groundwater that passed through the barrier.
1.5 EVALUATION OBJECTIVES
The evaluation was initially designed to achieve five specific objectives, including one primary
(P) objective and four secondary (S) objectives, as listed below:
P1 Determine the ability of the Regenesis in situ groundwater treatment technology to
significantly reduce the concentrations of each of the contaminants of concern (COC) in
the North of Basin F plume.
S1 Qualitatively evaluate the potential for the technology to achieve state and federal
regulatory clean-up goals for the site.
S2 Qualitatively evaluate the presence or absence of treatment-derived products and
indications of anaerobic conditions in groundwater samples.
S3 Qualitatively evaluate the COC concentrations in the peripheral monitoring wells located
along the string of downgradient wells.
S4 Obtain and evaluate data associated with the cost of implementation of the Regenesis
HRCŪ technology for the destruction or removal of COCs as encountered at RMA.
For purposes of implementing the evaluation objectives, the list of COCs and their associated
remediation goals included two components. First, the list included COCs identified in the 1996
Record of Decision (ROD) for the North Boundary Containment System at the RMA. These
eight COCs are listed in Table 1-2, along with the site-specific remediation goals listed in the
ROD.
10
-------
Table 1-2
Contaminants of Concern and Groundwater Remediation Goals
Contaminant of Concern
Di-isopropylmethyl phosphonate 2
Chlorophenylmethyl sulfide3
Chlorophenylmethyl sulfone3
Dieldrin2'3
Dicyclopentadiene3
Chloroform2'3
Methylene Chloride
Tetrachloroethene3
Contaminant
System
Remediation
Goal1
(Mg/L)
8
30
36
0.05
46
6
5
5
Notes:
1 North Boundary Containment System Remediation Goal
2 Also a Northwest Boundary Containment System COC
3 Also a Basin A Neck Treatment System COC
Second, the list included four additional compounds of regulatory interest, which are identified as
follows, along with their corresponding remediation goals:
Benzene, 3.0 g/L
TCE, 3.0 g/L
l,2-Dibromo-3-chloropropane (DBCP), 0.20 g/L
N-nitroso-dimethylamine, 0.007 g/L
The complete list of COCs for the evaluation included 12 compounds of direct regulatory interest
at the site.
11
-------
1.6 KEY CONTACTS
Additional information on the HRCŪ technology, the North of Basin F site, and the SITE
Program is available from the following sources:
Randy Parker
U.S. Environmental Protection Agency
National Risk Management Research Laboratory
26 West Martin Luther King Drive
Cincinnati, Ohio 45268
Telephone: (513) 569-7271
Fax:(513)569-7676
E-mail: parker.randy(a),epa.gov
12
-------
2.0 TREATMENT EFFECTIVENESS
This section presents the results of the evaluation of the Regenesis HRCŪ barrier at the North of
Basin F site at RMA.
2.1 EVALUATION APPROACH AND METHODS
The following sections describe the evaluation approach, including the experimental design,
sampling frequency, and sampling and analytical methods. Each of these elements of the overall
approach was designed to address the evaluation objectives.
2.1.1 Experimental Design
The HRCŪ barrier was installed to intercept groundwater flowing through the alluvial
paleochannel in the study area. Groundwater monitoring wells were installed parallel to the
paleochannel axis, both upgradient and downgradient from the barrier, to monitor the
technology's effectiveness during the evaluation. The experimental design for the technology
evaluation incorporated the analysis of groundwater samples from both the upgradient and
downgradient monitoring wells to determine the impact of the HRCŪ barrier on groundwater
quality.
2.1.2 Sampling Frequency
The evaluation sampling was conducted from February 2001 to October 2002. Three background
groundwater sampling events were conducted from February to May 2001, prior to barrier
installation, to establish background concentrations. Following injection of the HRCŪ barrier in
mid-May 2001, eight groundwater sampling events were conducted over an 18-month period to
determine the effectiveness of the technology in reducing contaminant concentrations in
groundwater downgradient from the barrier.
Based on an estimated groundwater flow velocity of 0.8 ft/day, the impacts of the barrier in the
furthest downgradient well were estimated to manifest within 6 weeks of barrier installation.
Over the anticipated 1-year post-injection test period, and based on an estimated groundwater
flow velocity of 0.8 ft/day, more than three pore volumes of groundwater were expected to pass
through the aquifer from the mid-point of the barrier to the furthest downgradient well. Therefore
results obtained toward the end of the 1-year period were expected to reflect a complete
displacement of the initial groundwater with groundwater that had passed through the barrier.
2.1.3 Sampling and Analytical Methods
Groundwater levels in each well were measured during each sampling event, and groundwater
samples were collected for a series of field and laboratory analyses. Groundwater samples were
collected using low-flow sample collection techniques to limit inclusion of otherwise immobile
colloids and target compounds that are sorbed to these particles. To facilitate sample collection,
each monitoring well was equipped with a dedicated submersible bladder pump positioned in the
middle, or slightly above the middle, of the saturated zone. Each well was purged at a pumping
rate of 0.1 liter per minute (L/min) to flush formation water through the dedicated pump, sample
tubing, and an in-line flow meter and water quality meter (flow-through cell) connected to the
tubing. Purge rates were then increased step-wise to a maximum rate of 0.5 L/min, and the water
level in the well casing was periodically monitored to ensure that draw-down did not exceed 0.1
meter (0.3 foot).
13
-------
Temperature, conductivity, oxidation-reduction potential (ORP), dissolved oxygen (DO), pH, and
turbidity were monitored every 5 minutes while purging with an in-line water quality meter.
Purging was continued until these parameters stabilize to within ą1.0 °F for temperature, ą3
percent for conductivity, ą20 millivolts (mV) for ORP, ą10 percent for DO, ą0.1 units for pH
over three consecutive readings, and a 20 percent range in readings for turbidity over three
consecutive measurements. Purging was continued until these parameters stabilized or three
casing volumes had been removed. Sample collection began immediately following purging.
Several laboratory tests were conducted on each groundwater sample to characterize the general
chemical properties, as well as to measure the specific target compounds of interest. The
parameters that were analyzed in each groundwater sample included the target COCs, degradation
parameters such as the organic acids that are released from the HRCŪ, and general groundwater
chemistry parameters. The methods used to analyze each of these parameters are listed in Table
2-1.
2.2 EVALUATION RESULTS
The results of the evaluation are described in the following sections, with respect to the impact of
the HRCŪ on groundwater chemistry, non-direct indicators of degradation rates and pathways,
and the observed trends in COC concentrations.
2.2.1 Impact of HRCŪ Injection on Groundwater Chemistry
Once injected into the subsurface, HRCŪ rapidly hydrolyzes to yield lactic acid. Anaerobic
degradation of lactic acid generates acetic acid and hydrogen, which facilitates the formation of
other volatile fatty acids, including propionic acid and butyric acid. As a result, the measurement
of these volatile fatty acids provides an indicator of HRCŪ activity in the subsurface.
Groundwater concentrations of lactic, propionic, butyric, and acetic acids over the entire period of
the evaluation are plotted in Figures 2-1 through 2-4, respectively. These time-series plots show
the concentration in each well, both upgradient and downgradient from the HRCŪ barrier, and
both before and after the HRCŪ injection. As shown in Figure 2-1, lactic acid concentrations rose
dramatically immediately following HRCŪ injection, but declined rapidly over the next several
months. Propionic, butyric, and acetic acid concentrations also rose immediately following
HRCŪ injection, but exhibited a slower initial rise and a slower decline as compared with lactic
acid. It should be noted that significant concentrations of these volatile fatty acids remained even
18 months after injection of the HRCŪ. The
14
-------
Table 2-1
Analytical Methods
Parameter
Method
Reporting
Units
Reference
Target COCs
Semivolatile Organics3
Volatile Organicse
Dieldrin
EPA Method 3510Cb/8270Cc
EPA Method 5030B/8260Bf
EPA Method 35 IOC/8081 A
ug/L
ug/L
ug/L
SW-846d
SW-846
SW-846
Degradation Indicators
Volatile Fatty Acids
Dissolved Gases'
Total Heterotrophs
Laboratory Standard Operating
Procedure (SOP)m
ASTMD-1945
SM9215
mg/L
mg/L
cru/mLn
Laboratory SOP
ASTMk
SMEWW1
General Chemistry
Total Organic Carbon
Total & Dissolved Metals8
Nitrite/Nitrate
Total Kjeldahl Nitrogen
Sulfate
Sulfide
Chloride
EPA Method 9060
EPA Method 30 10/60 10
EPA Method 353.2
SM 4500-N ORG
EPA Method 300.0
EPA Method 376.2
EPA Method 300.0
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
SW-846
SW-846
MCAWWh
SMEWW1
MCAWW
MCAWW
MCAWW
Notes:
Semivolatile organics include di-isopropylmethyl phosphonate, chlorophenylmethyl sulfide, chlorophenylmethyl
sulfone, dicyclopentadiene, n-nitrosodimethyl amine.
35 IOC was modified by performing the extraction at base/neutral pH conditions.
Modified according to Rocky mountain Arsenal (RMA) Method UM-58. The analyte list of 8270C was modified to
include the Semivolatile critical contaminants. Di-isopropylmethyl phosphonate and chlorophenylmethyl sulfone
will be included in one blank and matrix spike.
Test Methods for Evaluating Solid Waste, Physical/Chemical Methods, U.S. Environmental Protection Agency, SW-
846, Third Edition, 1986 with 12/96 Updates.
Volatile organics include benzene, chloroform, l,2-dibromo-3-chloropropane, methylene chloride, tetrachloroethene,
trichloroethene, and vinyl chloride.
Modified according to RMA Method UM-57.
Metals include iron and manganese.
Methods for the Chemical Analysis of Water and Wastes, U.S. Environmental Protection Agency, EPA 600/4-79-020,
1979, Revised March 1983.
Standard Methods for the Examination of Water and Wastewater, American Public Health Association, American
Water Works Association, and Water Environment Federation, 20th Edition, 1998.
Carbon dioxide, methane, ethane, and ethene.
American Society of Testing and Materials.
Laboratory method using high performance liquid chromatography with an ultraviolet absorption detector.
cfU/mL : colony forming units per milliliter.
15
-------
Figure 2-1 Lactic Acid
600
500 -
400 -
300 -
Concentration,
200 -
100 -
60C
50C
40C
30C
*Well 23006 bkgdW
4 Well 23256
X-Well 23257
Well 23258
Well 23259
Well 23262
Well 23265 bkgd S
Well 23263
Feb-01 Apr-01
Aug-02
Oct-02
16
-------
2500
-Well 23006 bkgdW
-+-Well 23256
-X-Well 23257
Jun-01 Aug-01 Oct-01
Feb-02 Apr-02 Jun-02 Aug-02 Oct-02
Figure 2-2 Propionic Acid
17
-------
100
90
Well 23006 bkgdW
+-Well 23256
X-Well 23257
X-Well 23258
-Well 23259
A-Well 23262
Well 23265 bkgd S
-Well 23263
1000
900
800
700
600
500
400
300
200
100
Feb-01 Apr-01 Jun-01 Aug-01 Oct-01 Dec-01 Feb-02 Apr-02 Jun-02 Aug-02 Oct-02
Date
Figure 2-3 Butyric Acid
18
-------
1400
1200
Well 23006
-+-Well 23256
-X-Well 23257
-X-Well 23258
--Well 23259
-A-Well 23262
--Well 23263
Well 23265
Apr-01
Jun-01
Aug-01
Oct-01
Dec-01 Feb-02
Date
Apr-02
Jun-02
Aug-02
Oct-02
Figure 2-4 Acetic Acid
19
-------
Ū
effect of HRC injection on ORP and pH are shown in the time-series plots in Figures 2-5 and 2-
6. As shown in the figures, ORP was reduced to less than 0 millivolts immediately following
HRCŪ injection, and remained negative in downgradient wells throughout the 18 months of post-
injection monitoring. The range of ORP values shown in the downgradient wells following
HRCŪ injection was consistent with anaerobic biodegradation. The pH of the groundwater was
also reduced in downgradient wells following HRCŪ injection due to the release of volatile fatty
acids, which act as weak acids, from the injected HRCŪ.
Although initial aquifer conditions were only mildly aerobic, a high HRCŪ dose rate was used
during the evaluation to overcome competing electron acceptors, including ferric iron and sulfate.
Hydrogen from HRCŪ is used to reduce these competing electron acceptors to create redox
conditions that are conducive to reductive dechlorination. Time-series plots for iron and sulfate
are shown in Figures 2-7 and 2-8, respectively. As shown in Figure 2-7, baseline ferric iron
concentrations in groundwater were low, but high levels of ferric iron on soil particles yielded
dissolved (ferrous) iron levels following injection of from 50 mg/L to more than 200 mg/L. The
ferrous iron concentrations reached maximum levels about 4 to 5 months after injection and then
began to decline gradually at most wells. As shown in Figure 2-8, sulfate concentrations fell
from an average baseline concentration of 550 mg/L to typically less than 100 mg/L. Despite the
high hydrogen demand presented by these competing electron acceptors, sufficient volatile fatty
acids (hydrogen source) remained, and ORP levels remained negative 1 8 months following
HRCŪ injection, and dechlorination appeared to continue throughout the evaluation period.
Total heterotrophic plate counts in the downgradient wells increased from an average of 537
colony- forming units per milliliter (cfu/mL) of groundwater before HRCŪ injection to 2,090
cfu/mL following HRCŪ injection. This increase reflects the growth of respiring microorganisms
as a result of HRCŪ injection. However, the total heterotrophic plate count data showed
substantial variability from sampling event to sampling event, and did not reveal any other clear
trends. Further, heterotrophic plate counts based on groundwater samples may not be reflective
of changes in the total microbial mass in the subsurface because a large fraction of that microbial
mass is in the form of attached growth.
2.2.2 COC Degradation Trends
Only 10 of the 12 identified COCs including DIMP, chlorophenylmethyl sulfide (CPMS),
chlorophenylmethyl sulfone (CPMSO2), dieldrin, dicyclopentadiene (DCPD), chloroform,
methylene chloride, PCE, benzene, and TCE were consistently detected in the monitoring wells
before injection of HRCŪ. Trends for n-nitrosodimethyl amine and l,2-dibromo-3-chloropropane
could not be evaluated due to lack of baseline data for comparison with post-injection
concentrations. The measured average background concentrations of these 10 COCs are
presented in Table 2-2. Groundwater concentrations of these 10 COCs, along with the TCE
degradation product cis-l,2-dicloroethene (DCE), over the entire period of the evaluation, are
plotted in Figures 2-9 through 2-19, respectively. These time-series plots show the COC
concentration in select wells, both upgradient and downgradient from the HRCŪ barrier, and both
before and after the HRCŪ injection, and compare these concentrations to the site-specific
remediation goals, where applicable.
Trends in COC concentrations were assessed using linear regression analysis, the Kendall Tau
Test, and nonlinear decay modeling. A description of the detailed statistical evaluation of the
groundwater analytical data using these models is provided in the TER. The overall trends shown
in each of the time-series plots is discussed below for each COC.
20
-------
250
Ŧ-Well23006bkgdW
X-Wei I 23256
X-Wei I 23257
-Well 23258
A-Well 23259
-Well 23262
Well 23263
*-Well23265bkgdS
0-Well23237bkgdFW
01 Apr-01
-550
Date
Figure 2-5 ORP
21
-------
7.5
c
-*-Well 23006 bkgdW
--Well 23237 bkgd FW
-X-Well 23256
-X-Well 23257
--Well 23258
-*-Well 23259
--Well 23262
Well 23263
Well 23265 bkgd S
4.5
Feb-01 Apr-01 Jun-01 Aug-01
Oct-01
Dec-01
Date
Feb-02 Apr-02 Jun-02 Aug-02
Oct-02
Figure 2-6 pH
22
-------
300
250 -
200 -
O)
1 150
is
c
01
o
c
o
O
100 H
--Well 23006 bkgdW
-*-Well 23237 bkgdFW
-+-Well 23256
-X-Well 23257
-X-Well 23258
--Well
-A-Well
Apr-01
Jun-01
Aug-01
Oct-01
Dec-01 Feb-02
Date
Apr-02
Jun-02
Aug-02
Oct-02
Figure 2-7 Iron
23
-------
1200
1000 -
800 -
)
E
c"
g
is
-------
Table 2-2
Contaminants of Concern and Average Baseline Concentrations
Notes:
Contaminant of
Concern
Average Baseline1
Concentration
milligrams per liter
(mg/L)
Di-isopropylmethyl phosphonate 0.520 (0.306)
Chlorophenylmethyl sulfide 0.0032 (0.0071)
Chlorophenylmethyl sulfone 0.048 (0.021)
Dieldrm
Dicyclopentadiene
Chloroform
Methylene Chloride
Tetrachloroethene
Trichloroethene 3
0.00060 (0.00087)
0.039 (0.072)
0.131 (0.280)
0.00332
0.014(0.019)
0.057 (0.048)
Benzene 3
0.0028 (0.00076)
1 Calculated for all wells; average for background (upgradient) wells only in
parentheses.
Secondary COC.
Not detected, value listed is the laboratory reporting limit.
25
-------
1200
1000
o>
D
c"
o
-------
Figure 2-10 CPMS
--Well 23006 bkgdW
-+-Well 23237 bkgdFW
-X-Well 23256
-X-Well 23257
--Well 23258
-A-Well 23259
--Well 23260
Well 23263
-*- Well 23262
Well 23265 bkgd S
Aug-02
Oct-02
27
-------
160
140
0
Feb-01
--Well 23006 bkgdW
-*- Well 23237 bkgd FW
-+Well 23256
-X-Well 23257
-X-Well 23258
--Well 23259
-A-Well 23262
--Well 23263
Well 23265 bkgd S
Apr-01
Jun-01
Aug-02 Oct-02
Figure 2-11CPMSO2
28
-------
--Well 23006 bkgdW
-*- Well 23237 bkgd FW
-+-Well 23256
-X-Well 23257
-X-Well 23258
--Well 23259
-A-Well 23262
--Well 23263
Well 23265 bkgd S
Feb-01 Apr-01 Jun-01 Aug-01 Oct-01 Dec-01 Feb-02
Date
Apr-02 Jun-02 Aug-02 Oct-02
Figure 2-12 Dieldrin
29
-------
160
140
-ŧ-Well 23006 bkgdW
+ Well 23256
-X-Well 23257
-X-Well 23258
--Well 23259
-A-Well 23262
--Well 23263
Well 23265 bkgd S
Well 23237 bkgd FW
Remediation Goal = 46 ug/L
Feb-01 Apr-01 Jun-01 Aug-01 Oct-01 Dec-01 Feb-02 Apr-02 Jun-02 Aug-02 Oct-02
Date
Figure 2-13 DCPD
30
-------
Figure 2-14 Benzene
--Well 23006 bkgdW
-+ Well 23237 bkgd FW
-X-Well 23256
-X-Well 23257
--Well 23258
-A-Well 23259
--Well 23260
Well 23262
Well 23263
Well 23265 bkgd S
Remediation Goal = 3 ug/L
0
Feb-01 Apr-01 Jun-01 Aug-01 Oct-01
Dec-01
Date
Feb-02 Apr-02 Jun-02 Aug-02 Oct-02
31
-------
Figure 2-15 Chloroform
500
450
o>
*-Well 23006 bkgdW
-Well 23237 bkgdFW
X-Well 23256
'X-Well 23257
-Well 23258
A-Well 23259
-Well 23260
Well 23262
Well 23263
Well 23265 bkgd S
Feb-01 Apr-01 Jun-01 Aug-01 Oct-01 Dec-01 Feb-02 Apr-02 Jun-02 Aug-02 Oct-02
Date
32
-------
Well 23006 bkgd W
--Well 23237 bkgd FW
-X-Well 23256
-X-Well 23257
--Well 23258
-A-Well 23259
--Well 23262
-4Well 23263
-*- Well 23265 bkgd S
Apr-02 Jun-02
Aug-02
Oct-02
Figure 2-16 Methylene Chloride
33
-------
-Well 23006 bkgdW
*- Well 23237 bkgd FW
+ Well 23256
X-Well 23257
X-Well 23258
-Well 23263
A-Well 23262
-Well 23265 bkgd S
Well 23259
Remediation Goal = 5 ug/L
Feb-01 Apr-01 Jun-01 Aug-01 Oct-01
Dec-01
Date
Feb-02 Apr-02 Jun-02 Aug-02 Oct-02
Figure 2-17 PCE
34
-------
120
100
O)
o
I
o
o
Ŧ-Well 23006 bkgd W
+-Well 23256
X-Well 23258
A-Well 23262
Well 23265 bkgd S
-*- Well 23237 bkgd FW
-X-Well 23257
--Well 23259
--Well 23263
20
0
Feb-01 Apr-01 Jun-01 Aug-01 Oct-01 Dec-01 Feb-02 Apr-02 Jun-02 Aug-02
Date
Figure 2-18 TCE
Oct-02
-------
40
35
30
--Well 23006 bkgdW
-*- Well 23237 bkgd FW
+Well 23256
-X-Well 23257
-X-Well 23258
--Well 23259
-A-Well 23262
--Well 23263
Well 23265 bkgd S
Apr-01
Jun-01
Aug-01
Oct-01
Dec-01 Feb-02
Date
Figure 2-19 DCE
Apr-02
Jun-02
Aug-02
Oct-02
36
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DIMP
The time-series plot for DIMP (Figure 2-9) shows a distinct decreasing trend for five wells
immediately downgradient from the HRCŪ barrier (wells 23255, 23256, 23257, 23260, and
23261). For all these wells, the decreasing trend was statistically significant by the Kendall Tau
Test. Overall declines in DIMP concentrations at these wells over the course of the evaluation
ranged from 50 to 80 percent, based on maximum pre-injection concentrations between 280 and
720 ug/L. However, the post-injection concentrations for DIMP remained well above the site-
specific remediation goal of 8 ug/L.
DIMP concentrations in other downgradient wells were more variable, but tended to show slight
declines, whereas concentrations in upgradient wells were variable or increasing throughout all
sampling events. Wells further downgradient showed apparent decreases in concentrations of 15
to 20 percent. After about 5 to 6 months, DIMP concentrations appeared to stabilize.
CPMS
The time-series plot for CPMS (Figure 2-10) shows the lack of clear trends in CPMS
concentrations in the downgradient wells following installation of the HRCŪ barrier. This lack of
trends suggests that degradation of CPMS was not accelerated by injection of the HRCŪ barrier.
Concentrations appeared to increase to a maximum of between 6 and 24 ug/L in the middle of the
evaluation (sampling events five through eight), and then declined. No CPMS concentrations
were reported above the remediation goal of 30 ug/L during the evaluation.
CPMSO2
The time-series plot for CPMSO2 (Figure 2-11) also shows no clear trends in CPMSO2
concentrations in the downgradient wells following installation of the HRCŪ barrier. This lack of
clear trends suggests that degradation of CPMSO2 was not accelerated by the injection of HRCŪ.
Dieldrin
The time-series plot for dieldrin (Figure 2-12) does not show any well-defined or consistent
trends for this COC in the downgradient wells. However, only two wells (upgradient well 23006
and downgradient well 23259) exhibited dieldrin concentrations greater than 1 ug/L during the
evaluation period. Given the overall low concentration levels observed, sampling and analytical
imprecision may have affected the results for this COC, and it is impractical to conclude whether
any increased degradation of this COC occurred as a result of the HRCŪ injection.
DCPD
The time-series plot for DCPD (Figure 2-13) shows a decreasing trend for most of the
downgradient wells. The largest overall decline was observed at well 23259, where the DCPD
concentration dropped almost 90 percent by the end of the evaluation from a maximum pre-
injection concentration of 100 ug/L. Other wells displaying overall DCPD reductions in the 90
percent range include wells 23258, 23262, and 23263. Post-injection concentrations at these
wells were consistently below the remediation goal of 46 ug/L. Compared with the downgradient
wells, no significant trend was observed for DCPD in the single upgradient well in which it was
detected, indicating that degradation was occurring in the HRCŪ barrier.
37
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Benzene
The time-series plot for benzene (Figure 2-14) shows decreasing concentrations at most
downgradient wells following HRCŪ injection, indicating that degradation was occurring in the
HRCŪ barrier. The decreasing trend was greatest at well 23259, where the concentration was
reduced from a pre-injection maximum of 10 ug/L to post-injection concentrations just below 2
ug/L (greater than 80 percent reduction). Post-injection concentrations were also reduced at
several other downgradient wells to the 1 to 2 ug/L range, but from lower initial (pre-injection)
concentrations (2 to 6 ug/L). The post-injection concentrations of benzene in the downgradient
wells declined to concentrations below the remediation goal of 3 ug/L.
Chlorinated Methanes (Chloroform and Methylene Chloride)
The time-series plot for chloroform in Figure 2-15 shows that concentrations of chloroform were
highly variable in upgradient and downgradient wells, with few definitive trends. The general
variability of the chloroform results and the declining trend prior to HRCŪ injection complicated
the evaluation of contaminant reduction by the HRCŪ technology; therefore, no percent
reductions were estimated. Moreover, none of the downgradient wells displayed post-injection
concentrations that were consistently below the remediation goal of 6 ug/L.
Methylene chloride was identified as a COC not only based on its historical occurrence at RMA,
but also because it can be produced by reductive dechlorination of chloroform. However, this
COC was detected only in one upgradient and four downgradient wells during the HRCŪ
evaluation, and concentrations were generally below 10 ug/L. The time-series plot for methylene
chloride (Figure 2-16) shows that post-injection concentrations of methylene chloride were
consistently below the remediation goal of 5 ug/L in wells 23256, 23257, and 23259.
Chlorinated Ethenes (PCE, TCE, DCE, vinyl chloride)
The time-series plot for PCE (Figure 2-17) shows a decline in concentration over the course of
the HRCŪ evaluation for wells upgradient and downgradient from the HRCŪ barrier. Except for
upgradient well 23006, the post-injection concentrations in the well network stabilized below the
remediation goal of 5 ug/L, and were generally closer to the method reporting limit of 0.73 ug/L.
The largest percent reduction in PCE during the evaluation was observed at downgradient well
23259, where the concentration declined from a pre-injection maximum of 45 ug/L to between
0.75 and 1.9 ug/L over the last five post-injection sampling events (greater than a 95 percent
reduction). The declines observed in the upgradient wells were consistent with the recent overall
declines in PCE concentration observed in this area of RMA due to the operation of an extraction
well (well location 23311). This extraction well operated from 1996 to 2000, and produced
notable declines in PCE and chloroform concentrations beginning in 1998.
TCE is the initial daughter product from reductive dechlorination of PCE. The time-series plot
for TCE (Figure 2-18) shows few overall trends. No wells attained the remediation goal of 3
ug/L for TCE by the end of the evaluation. The lack of any overall significant reductions in TCE
concentrations following HRCŪ injection may reflect a relative balance between creation of TCE
as a daughter product and anaerobic degradation of PCE.
Though not a COC, cis-l,2-DCE is formed through the reductive dechlorination of TCE. The
time-series plot for cis-l,2-DCE (Figure 2-19) shows increases in concentration during the
evaluation for one upgradient and eight downgradient wells. Specifically, cis-l,2-DCE
concentrations increased from pre-injection values below 5 ug/L to post-injection concentrations
38
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between 10 and 40 ug/L at the end of the evaluation, with the largest increases observed at wells
23258, 23262, and 23263. For some wells, the magnitude of the cis-l,2-DCE concentration
increase showed an approximate correlation with TCE degradation. For example, well 23263
displayed a decline of approximately 50 ug/L in TCE concentration over the course of the
evaluation, along with an increase of approximately 35 ug/L in cis-l,2-DCE concentration. This
decline amounts to a decrease of 0.38 micromoles of TCE that corresponds with an essentially
equivalent increase of 0.36 umol of cis-l,2-DCE. However, such correlations were not apparent
for all wells. Overall, these results appear to reflect the creation of cis-l,2-DCE as a daughter
product of TCE degradation and the lack of any significant degradation of cis-l,2-DCE.
Upon further dechlorination, cis-l,2-DCE degrades to vinyl chloride. In turn, vinyl chloride can
be dechlorinated through either aerobic or anaerobic processes to form the fully hydrogenated
compound ethylene. Because no detections were reported for either vinyl chloride or ethylene
during the evaluation, trends for these compounds could not be assessed. It should be noted,
however, that the sample reporting limits obtained for ethylene (5 to 12 ug/L) may have generally
been too high to detect ethylene formation given the levels of TCE and cis-l,2-DCE reported in
the well network during the evaluation period.
2.2.3 Quality Control Program
A quality assurance project plan (QAPP) outlining the evaluation activities and planned quality
control procedures was completed and approved by project participants (Tetra Tech EM Inc.
[Tetra Tech] 200la; 200Ib). As required by the QAPP, various field and laboratory quality
control (QC) checks were implemented during the evaluation.
A full data quality review was also conducted to evaluate all field and laboratory results,
document data use limitations for data users, and remove unusable values from the evaluation
data sets. This effort included reviews of sample chains-of-custody, holding times, and critical
parameter identification and quantification. The results of this review were used to produce the
final data sets used to assess the HRCŪ technology.
Field QC samples included field blanks, field duplicates, equipment blanks, and trip blanks. Field
QC checks were also conducted to determine the quality of field activities, including sample
collection, handling, and shipment.
Laboratory QC samples, including laboratory control samples and laboratory control sample
duplicates (LCS/LCSD) and matrix spike/matrix spike duplicates (MS/MSD), were also
processed according to the reference methods identified in Table 2-1 and the QAPP. Laboratory
QC checks were designed to determine analytical precision and accuracy, demonstrate the
absence of interferences and contamination from glassware and reagents, and ensure the
comparability of data.
A review of the QC sample results did not indicate any broad QC issues or overall limitations on
the data. Some results were flagged as estimated because the precision and accuracy objectives
were exceeded in the MS/MSD results, but the number of estimated results was small, and none
of these results impacted the overall assessment of data trends. The TER contains a detailed
assessment of QC sample results and other QC checks for each sampling event.
39
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2.3 EVALUATION OF RESULTS AGAINST THE OBJECTIVES
The evaluation was designed to achieve five specific objectives, including one primary (P)
objective and four secondary (S) objectives. The results of the evaluation, described in the
previous section, are evaluated against each of these objectives in the following sections. In each
section, the objective is listed first, followed by a discussion of whether the results met this
objective.
2.3.1 Objective PI
PI Determine the ability of the Regenesis HRCŪ treatment technology to significantly reduce
the concentrations of each of the primary COCs in the North of Basin F plume.
The objective was evaluated by comparing upgradient and downgradient COC concentrations in
groundwater to determine reductions in the COCs. After initial distribution testing using the
Shapiro-Wilk Test and the generation of summary statistics and plots for the pre- and post-
injection data sets, statistical evaluation of the analytical data from the HRCŪ evaluation focused
on the identification of general and significant trends in results for the 10 COCs and selected
degradation products. As described in Section 2.2.2, this evaluation involved the preparation of
time-series plots, linear and nonlinear regression analysis, and application of the Kendal Tau Test
for trends. Statistical evaluation of the data is discussed further in the TER.
The evaluation found decreasing trends for the following COCs: PCE, TCE (after an initial
increase in concentration at some wells), DIMP, DCPD, and benzene. Percent reductions for
these COCs were generally in the 50 to 80 percent range at multiple downgradient wells, although
higher percent reductions were observed for PCE and DCPD (90 to 95 percent). Except for TCE
and DIMP, downgradient concentrations of these COCs were reduced over the course of the
evaluation to below applicable site-specific remediation goals. Based on the evaluation results,
the HRCŪ barrier appears to have facilitated the degradation of these five COCs at RMA.
Increasing trends in concentrations were observed in the evaluation data for cis-l,2-DCE, a
daughter product from the reductive dechlorination of TCE. However, further degradation of cis-
1,2-DCE to vinyl chloride and ethylene was not observed.
CPMS increased in many wells as the evaluation progressed, but then declined in the later
sampling events. Conditions created by HRCŪ may have produced CPMS from CPMSO2, which
then further degraded. The analytical data for the remaining COCs, including chloroform,
methylene chloride, CPMSO2, and dieldrin, were variable and did not show significant or
consistent trends for the set of wells sampled overthe 18-month post-injection period.
2.3.2 Objective SI
SI Qualitatively evaluate the potential for the technology to achieve state and federal
regulatory clean-up goals for the site.
This objective evaluated the technology's ability to achieve state or federal clean-up or
remediation goals as specified in the ROD for this site. Evaluation of this objective focused on
wells 23259 and 23262, located furthest downgradient from the HRCŪ injection wall. The
qualitative analysis for this objective consisted of generating concentration versus time plots for
the COCs and comparing the data graphically to remediation goals. As described in Section
2.2.2, the post-injection concentrations of DCPD, PCE, and benzene at wells 23259 and 23262
40
-------
were the only COCs that showed post-injection concentrations consistently below the
corresponding remediation goals of 46 (ig/L, 5 (ig/L, and 3 (ig/L, respectively.
The concentrations of CPMSO2 and chloroform were also below the remediation goals for the
furthest downgradient wells (23259 and 23262) during post-injection sampling events. However,
the time series plots did not show any well-defined or consistent trends for the two downgradient
wells, which suggested that this achievement was the result of HRCŪ injection. Methylene
chloride was consistently detected below the remediation goal of 5 (ig/L in other downgradient
wells, but not in the furthest downgradient wells selected for this objective.
2.3.3 Objective S2
S2 Qualitatively evaluate the presence or absence of treatment-derived products and
indications of anaerobic conditions in groundwater samples.
This objective was evaluated by comparing pre- and post-injection data for groundwater
chemistry with treatment-derived products, including volatile fatty acids, degradation by-
products, and certain inorganic constituents in groundwater. The qualitative analysis for this
objective consisted of generating concentration versus time plots for these parameters.
As described in Section 2.2.1, lactic acid concentrations increased dramatically following HRCŪ
injection. Propionic, butyric, and acetic acid concentrations also increased dramatically following
HRCŪ injection, but exhibited a slower initial increase and slower decline compared with lactic
acid.
A high HRCŪ dose rate was used during the evaluation to overcome competing electron
acceptors, including ferric iron and sulfate. Despite the high hydrogen demand presented by
these competing electron acceptors, the following data indicate that active anaerobic
biodegradation was sustained throughout the evaluation period: (1) sufficient volatile fatty acids
remained throughout the 18 months of post-injection monitoring; (2) ORP levels were reduced to
less than 0 mV and remained negative during the 18 month period; and (3) the pH of groundwater
in all downgradient wells was reduced following HRCŪ injection due to the release of volatile
fatty acids.
The lack of overall significant reductions in TCE concentrations following HRCŪ injection may
reflect a relative balance between creation of TCE as a daughter product and anaerobic
degradation of TCE. This correlation was also apparent in the data for cis-l,2-DCE, which is a
degradation product of TCE. For some wells, cis-l,2-DCE concentrations increased, which
showed an approximate correlation with TCE degradation. Cis-l,2-DCE further degrades to
vinyl chloride, which can be dechlorinated to form the fully hydrogenated compound ethylene.
Although no detections were reported for vinyl chloride or ethylene during the evaluation, the
limited ability of the analytical methods to detect these compounds may have been the cause.
2.3.4 Objective S3
S3 Qualitatively evaluate the COC concentrations in the peripheral monitoring wells located
along the string of downgradient wells.
The planned HRCŪ permeable barrier was enlarged and changed to an L-shape, as described in
Section 1.4.2, following formation of the evaluation objectives. The design was changed to
ensure interception of all groundwater flowing to the downgradient wells regardless of minor
41
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changes in groundwater flow direction. Thus, all downgradient wells were considered
collectively in the data analysis, and Objective S3 ceased to be a separate objective.
2.3.5 Objective S4
S4 Obtain and evaluate data associated with the cost of implementation of the Regenesis HRCŪ
technology for the destruction or removal ofCOCs as encountered at RMA.
A detailed discussion of costs associated with implementation of the HRCŪ technology is
included in Section 3.0 of this report.
42
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3.0 ECONOMIC ANALYSIS
This economic analysis presents estimated costs for commercial application of the HRCŪ
technology to enhance natural anaerobic degradation of chlorinated organic compounds in
groundwater. The cost data provided in this section are for a barrier-based design, as was
demonstrated at the RMA North of Basin F site. The estimates are based on the assumptions and
costs provided by Regenesis; data compiled during the SITE technology evaluation; information
provided by the site engineering and operations contractors; and additional information obtained
from current construction cost estimating guidance, as well as SITE Program experience. For
comparability, these costs have been placed into the 12 categories applicable to typical clean-up
activities at Superfund and Resource Conservation and Recovery Act (RCRA) sites (Evans 1990).
The costs presented in this section are considered to be order-of-magnitude estimates.
3.1 GENERAL ISSUES AND ASSUMPTIONS
Prior to presenting the cost estimate for the selected application, it is important to describe how
costs associated with the HRCŪ application can vary based on numerous factors, such as the type
and scale of the application, contaminant types and levels, regulatory criteria, and site-specific
factors. Sections 3.1.1 through 3.1.4 discuss some of the primary factors that affect the cost of an
HRCŪ system. Section 3.1.5 discusses general assumptions used in the subsequent cost analysis
provided in Section 3.1.5.
3.1.1 Type and Scale of Application
The HRCŪ technology would typically be used as an in situ treatment of groundwater
contaminated with chlorinated organic compounds. In a remedial application, HRCŪ may be
used at a RCRA corrective action or Superfund site. There are two basic conceptual designs of
the HRCŪ system:
Grid-based design
Barrier-based design
A grid-based design is generally applicable to relatively small contaminant plumes where it is
cost effective to inject HRCŪ at closely spaced intervals (approximately 5 to 10 feet) throughout
the plume. The plume may be remediated with a single treatment event. The shape of the grid
and number of injection points is determined from the shape and areal extent of the plume. The
injection intervals are based on the saturated thickness and vertical extent of contamination.
For larger contaminant plumes, where the grid-based design is not cost effective, a barrier-based
design may be applicable. The barrier design is essentially a containment strategy. HRCŪ
injection points are aligned in a row or a few rows across the axis of the plume and perpendicular
to the direction of contaminant migration. This type of design requires fewer injection points, but
will likely require repeat treatments on an approximate annual basis. The time required to
achieve remedial objectives may range from years to decades.
3.1.2 Contaminant Types and Levels
Factors affecting the mass of HRCŪ required to remediate a contaminant plume include the
following:
Characteristics of the individual contaminants
43
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Concentration or mass of the contaminants
Naturally occurring chemicals that may inhibit HRCŪ chemical reactions
In dechlorination chemistry, HRCŪ acts as the electron donor while the chlorinated organic
compounds act as electron acceptors. Essentially, the chlorine atoms of the chlorinated organic
compounds are replaced with the hydrogen of the HRCŪ and the compound is thereby
dechlorinated. Thus, the mass of HRCŪ required for remediation is proportional to the type and
mass of the contaminants. However, some naturally occurring chemical species, such as oxygen
and iron, are competing electron acceptors and will inhibit the HRCŪ remediation process. The
mass of HRCŪ may have to be increased to compensate for the additional electron demand.
3.1.3 Regulatory Criteria
Permitting requirements for this type of application would typically include an underground
injection permit. Some regulatory entities may also require permits for boring/well installation.
Benchmark concentrations established in the remedial action objectives must be considered when
determining the mass of HRCŪ required and the period of remediation.
Regulatory agencies will generally require a monitoring program to assess the performance of the
remedial system over time. This program will likely consist of periodic groundwater sampling
until the remedial action is complete. More stringent regulatory criteria for the treated
groundwater can affect the HRCŪ dose rate and the effluent monitoring costs.
3.1.4 Site-Specific Features
Site-specific issues include aquifer characteristics, site access, existing structures, and
underground utilities. Depending on the nature of the site, these factors may considerably affect
costs.
The density of naturally occurring microorganisms that are capable of degrading chlorinated
organic compounds is also a consideration. For HRCŪ to work, native anaerobic biota must be
present in the subsurface soil or bedrock. If an aquifer has a high microbial population, it will
metabolize a given mass of HRCŪ at a faster rate and achieve faster contaminant reductions. It is
likely that a treatability study will be required to determine the presence of a sufficient native
microbial population to support the remediation scenario and to assist with the overall design.
3.1.5 General Assumptions
Certain assumptions were made to simplify the cost estimating. Real-world situations would
require complex engineering and financial considerations. The following general assumptions
were made for the cost analysis:
Costs are rounded to the nearest $ 10
Seventeen percent was added to unit costs and labor rates to account for general and
administrative costs. An additional 15 percent was added to labor rates for field
work to account for health and safety monitoring and equipment
A treatability study will be conducted to determine initial contaminant
concentrations, competing electron acceptors, and microbial population
Aquifer characteristics are similar to those presented on Table 3-1
44
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Initial contaminant concentrations are similar to those presented on Table 3-2
Competing electron acceptors are similar to those presented on Table 3-3
A barrier-based design application is used
Drilling locations are readily accessible
Costs were calculated for 1 year only; other factors are noted, besides inflation, that
may affect the costs in subsequent years.
3.2 HRCŪ REMEDIAL APPLICATION
The estimated costs for the HRCŪ remedial application are presented on Table 3-4. The
following sections provide the bases for the cost calculations associated with each of the
following 12 cost categories: (1) site preparation, (2) permitting and regulatory, (3) mobilization
and startup, (4) equipment, (5) labor, (6) supplies, (7) utilities, (8) effluent treatment and disposal,
(9) residual waste shipping and handling, (10) analytical services, (11) equipment maintenance,
and (12) site demobilization.
3.2.1 Site Preparation Costs
Site preparation can vary considerably. These costs typically include preliminary costs necessary
to physically prepare the site for access by a direct-push drill rig, treatability studies, site-specific
design of the remedial system, and project-related administration and management. For this
application, it was assumed that drilling locations were accessible by a truck-mounted drilling rig,
and that the property owner's permitted access and demolition of existing structures was not
required. It was assumed that physical preparation of the site consisted of an underground utility
survey at a cost of $1,000.
It was assumed that a treatability study would be conducted at the site and a hydrogeologic
investigation was already completed and therefore not included as part of the study. For this
scenario, it was assumed that eight soil and eight water samples would be collected from three
45-foot borings with a direct-push rig. Total cost of the drilling, field supplies, shipping, and
labor for sample collection is estimated to be $7,880. The cost for laboratory analysis of the
samples was assumed to be $10,000. The samples would be analyzed for the COCs, volatile fatty
acids, dissolved gases, filtered and total inorganics, microbial population, and field parameters. It
should be noted that treatability study costs can vary considerably and are highly dependent on
the site, COCs, and amount of site characterization data already available.
Once the treatability study has been conducted, the design of the remedial system can be readily
accomplished. Information can be entered into a spreadsheet where the amount of HRCŪ is
automatically calculated. This service is typically provided at no charge by Regenesis.
Project management and administrative expenses were estimated to be $1,890. Total site
preparation costs were estimated to be $20,770.
45
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Table 3-1
Aquifer Characteristics
Parameter
Soil Type
Depth to groundwater
Hydraulic conductivity1
Hydraulic gradient2
Saturated thickness
Length of barrier
Area3
Volumetric flow rate4
Volumetric flow rate
Value
Unconsolidated
sand and gravel
44
89
0.0009
10
250
2,500
200
1,496
Units
feet
feet per day
unitless
feet
feet
square feet
cubic feet per day
gallons per day
Notes
Saturated thickness x length of barrier
From Darcy's Law (Q=KAI)
Notes:
1 Identified as K in Darcy's Law.
Identified as I in Darcy's Law
Identified as A in Darcy's Law
Identified as Q in Darcy's Law, where Q = KAI
46
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Table 3-2
Initial Contaminant Concentrations
Parameter
Diisopropylmethylphosphonate
Chlorophenylmethyl sulfide
Chlorophenylmethyl sulfone
Dieldrin
Dicyclopentadiene
Chloroform
Methylene Chloride
Tetrachloroethene
Trichloroethene
Benzene
Total
Baseline
Concentration
ftig/L)
800
not applicable2
80
1
100
200
NA
20
80
10
21,291
Mass Flux1
(gallons/year)
61,660
-
166
2.1
207
414
41.4
166
20.7
2,677
Notes:
'Based on volumetric flow rate of 1,496 gallons per day or 546,000 gallons per
year.
2Compound concentration was below detection limit or remedial goal.
Table 3-3
Geochemical Parameters
Parameter
Oxygen (O2)
Nitrate (NO3)
Manganese (Mn)
Iron (Fe)
Sulfate (SO4)
Effective Concentration
(HS/L)
2,000
500
20,000
100
400
47
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Table 3-4
2003 Estimated Costs by Category
Category
Site Preparation
Permitting and Regulatory
Mobilization and Startup
Equipment
Labor
Supplies
Utilities
Effluent Treatment and
Disposal
Residual Waste Shipping
and Handling
Analytical Services
Equipment Maintenance
Site Demobilization
Task
Utility Survey
Treatability Study
Vendor Design
Project Management
UIC Permit
Work Plan
Project Management
HRCŪ Injection
Install 7 Monitoring Wells
Project Management
Survey 7 Wells
Dedicated Sampling Pumps
Pump Installation
Performance Sampling
Manage Data
Rental Equipment and
Expendables
Not Applicable for this
Scenario
Not Applicable for this
Scenario
Not Applicable for this
Scenario
Laboratory Analysis
Shipping
Not Applicable
Decommission Wells
Item
Subcontractor
Labor
Drilling Subcontractor
Laboratory
Field Supplies
Labor
Labor
Labor
Labor
HRCŪ Material
Labor
Drilling Subcontractor
Drilling Subcontractor
Labor
Labor
Subcontractor
Pumps
Labor
Labor
Labor
-
-
-
-
See Section 3. 2. 10 for
Specific Analyses
-
-
Drilling Subcontractor
Item
Cost
$1,000.00
$3,280.00
$4,000.00
$10,000
$600.00
$0.00
$1,890.00
$1,590.00
$13,200.00
$1,380.00
$81,750.00
$18,040.00
$32,500.00
$24,700.00
$9,560.00
$1,870.00
$1,500.00
$4,100.00
$1,040.00
$20,120.00
$6,670.00
$5,670.00
$0.00
$0.00
$0.00
$46,500.00
$1,000.00
$0.00
$8,600.00
Category
Total
$20,770
$16,170
$169,920
$5,140
$26,790
$5,670
$0
$0
$0
$47,500
$0
48
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Labor
$1,800.00
II Total Estimated Cost
$10,400
$302,360)
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3.2.2 Permitting and Regulatory Costs
Permitting and regulatory costs are highly dependent on site-specific factors, site regulatory status
(such as whether treatment is performed at a Superfund or RCRA corrective action site), and how
any wastes are disposed of. Superfund site remedial actions must be consistent with applicable
and relevant or appropriate requirements (ARAR) that include environmental laws, ordinances,
regulations, and statutes, including federal, state, and local standards and criteria. Remediation at
RCRA corrective action sites requires additional monitoring and recordkeeping, which can
increase base regulatory costs. In general, ARARs must be determined on a site-specific basis.
For this application, it was assumed that a permit for underground injection control (UIC) would
be required. Costs for obtaining the permit were estimated to be $ 1,590.
Regulatory agencies typically require a work plan and health and safety plan for implementing
this type of remedial action. Costs for labor associated with preparation of the plans are
estimated to be $13,200. Project management and administrative costs are estimated to be
$1,380. Total permitting and regulatory costs are estimated to be $16,170.
3.2.3 Mobilization and Startup Costs
The remedial design for this scenario assumed a 250-foot barrier application, 150 HRCŪ injection
points to a depth of 54 feet, with an estimated 10 feet of saturated thickness at each location.
HRCŪ would be injected at a rate of 9.1 pounds per foot of saturated thickness, or 91 pounds per
location. The remedial system would be installed with a direct-push drill rig that averaged eight
injection points, or 432 feet per day.
At a cost of $5.50 per pound of HRCŪ and accounting for shipping and tax, the cost of the HRCŪ
material is estimated at $81,750. The cost of the drilling subcontractor is estimated at $32,500.
The labor cost for a geologist to conduct oversight during HRCŪ injection is estimated at
$18,040.
In addition to the HRCŪ injection, it was assumed that seven monitoring wells would be installed
to a depth of 55 feet for system performance monitoring. Investigation-derived waste (IDW) is
assumed to be disposed of at the site's treatment, storage, and disposal facility. It is estimated to
require 9 days to complete the task. The cost of the drilling subcontractor to drill, install, and
develop the wells is estimated at $24,700. The labor for a geologist to conduct oversight during
monitoring well installation activities is estimated at $9,560. The cost of surveying the wells is
estimated at $1,500.
Project management and administrative costs are estimated to be $1,870. Total mobilization and
startup costs are estimated at $169,920.
3.2.4 Equipment Costs
The HRCŪ remedial system is passive; therefore, equipment required for this remedial scenario is
primarily that used to inject the HRCŪ material. These costs are included under Mobilization and
Startup Costs (Section 3.2.3). For this application, it was assumed that operational equipment
would consist of dedicated bladder pumps installed in the seven performance monitoring wells
discussed in Section 3.2.3. The cost of seven pumps, including tubing, fittings, and freeze
protection, is estimated to be $4,100. Installation of the pumps is estimated to cost $1,040. Total
equipment costs are estimated to be $5,140.
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3.2.5 Labor Costs
Once the HRCŪ is injected, no further field activity is required except for performance
monitoring until the HRCŪ material is expended and re-application is warranted. According to
Regenesis, re-application generally occurs on an approximately annual basis. For this remedial
scenario, it was assumed that the seven performance monitoring wells would be sampled five
times during 1 year of treatment. The monitoring events would be conducted at 2 months, 4
months, 6 months, 9 months and 12 months following the first HRCŪ treatment event. It is
assumed that IDW can be disposed of at the site's treatment, storage, and disposal facility. It was
estimated that each sampling event would require 2 days of field work. It is estimated that the
labor cost for the five sampling events would be $20,120. It is assumed that some data
management will also be required. The labor cost for this task is estimated at $6,670. Total cost
for this category is $26,790.
Performance monitoring is typically conducted frequently during the initial stages of a remedial
action and is reduced during subsequent years as more site-specific knowledge is gained. This
monitoring may include a reduction in the number of wells that are sampled. It is likely that
performance monitoring would also be reduced for this remedial scenario; thus, the labor costs in
subsequent years may be significantly reduced.
3.2.6 Supply Costs
Supplies for this remedial scenario consist of those materials required to conduct the performance
sampling. These supplies include rental equipment such as a pump controller, compressed gas for
pump operation, air monitoring equipment, water level indicator, and water quality meters for
DO, ORP, pH, and temperature. Expendable supplies include water filters, field calibration
solutions, personal protective equipment, buckets for purge water, sample bottles, shipping
containers, ice, duct tape, and other miscellaneous supplies. The supply costs are estimated to be
$5,670 for five sampling events during the first year. As with Labor Costs (Section 3.2.5), these
costs may be reduced in subsequent years due to reduced monitoring frequency.
3.2.7 Utility Costs
The HRCŪ remedial system is passive and requires no field operations other than performance
monitoring. Utilities associated with performance monitoring would consist primarily of batteries
for the water quality meters and water for decontamination. The estimated costs assume that the
batteries will be included with the rental equipment and that water is readily available at the site.
For this reason, this cost estimate assumes no utility costs.
3.2.8 Effluent Treatment and Disposal Costs
The waste generated during routine operations would consist only of purge water and IDW. It is
assumed that this material requires no treatment and can be disposed of on site. For this reason,
this cost estimate assumes no effluent treatment and disposal costs.
3.2.9 Residual Waste Shipping and Handling Costs
Residual waste would be expected to consist of a relatively small volume of purge water and
IDW. It is assumed that this waste can be disposed of on site. Costs associated with transport
and handling of the residual waste would be primarily labor. The labor costs for this item are
included in the cost estimate for the Labor category provided in Section 3.2.5.
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3.2.10 Analytical Services Costs
Analytical services include costs for laboratory analyses, data reduction, and QC. It is assumed
that groundwater samples collected during the five performance sampling events will be analyzed
for VOCs, semivolatile organic compounds (SVOC), pesticides, major anions, filtered metals,
total metals, volatile fatty acids, dissolved gases, and heterotrophic plate counts. These analyses
are assumed to be analyzed in accordance with RMA methodologies and encumber RMA costs.
The cost estimate also includes analysis of all associated QC samples. The estimated analytical
cost for five sampling events, including shipping, is estimated to be $47,500. As discussed in
previous sections, these costs will likely decrease as a result of reduced sampling frequency in
subsequent years.
3.2.11 Equipment Maintenance Costs
The dedicated bladder pumps are the only equipment required for this remediation scenario. The
estimate assumes that bladder pumps would not require maintenance during the first year of use.
For this scenario, HRCŪ treatment is expected to last only 1 year; therefore, this cost estimate
assumes no maintenance costs.
3.2.12 Site Demobilization Costs
Site demobilization includes decommissioning of the seven performance monitoring wells when
the remedial objectives are attained. It is assumed that the services of a driller will be required
for an estimated 2 days to decommission the wells. The cost of drilling services is estimated at
$8,600. The labor cost for a geologist to conduct oversight during well decommissioning is
estimated at $1,800. Total demobilization costs are therefore estimated at $10,400.
3.3 CONCLUSIONS OF THE ECONOMIC ANALYSIS
This analysis presents costs for treating groundwater contamination using an HRCŪ barrier. The
estimate is based on actual costs experienced at RMA for 1 year. The treatment event is expected
to last approximately 1 year at a cost of approximately $302,360. The aquifer characteristics
described in Table 3-1 indicate that approximately 546,040 gallons of contaminated groundwater
would migrate through the treatment barrier per year. This treated volume translates to a cost of
approximately $0.55 per gallon of water. A breakdown of the relative costs by category is
provided on Figure 3-1.
The unit cost provided in the preceding paragraph reflects expenses relative to the first year of
remediation. It must be recognized that some first-year expenses are likely one-time expenses.
Examples of likely one-time expenses are as follows:
Site preparation costs
Permitting and regulatory costs
Equipment costs, although over a period of years there may be some minimal costs
associated with maintenance of the bladder pumps
Installation of performance monitoring wells in the mobilization and startup
category
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In addition to one-time expenses, the frequency of monitoring would likely decrease in
subsequent years. This decrease would reduce costs in the labor, supply, and analytical services
categories proportionately; thus, the unit cost of treated water would likely decrease if HRCŪ
treatment is considered for a longer period of time.
Figure 3-1
HRCŪ Estimated Cost Breakdown
Site Demobilization 3.4%
Site Preparation 6.9%
Analytical
Services 15.7%
Supplies 1.9%
Labor 8.9%
Mobilization and
Startup 56.2%
Equipment 1.7%
Permitting and
Regulatory 5.4%
Notes:
Utilities, effluent treatment and disposal, residual waste sampling, and equipment
maintenance categories
were not included, because they do not appear to be applicable to this remedial application.
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4.0 TECHNOLOGY APPLICATIONS ANALYSIS
This section of the report discusses the following topics regarding general applicability of the
Regenesis HRCŪ technology: factors affecting technology performance, site characteristics and
support requirements, material handling requirements, technology limitations, potential
regulatory requirements, and state and community acceptance. This analysis is based primarily
on the evaluation results at the RMA site; however, the evaluation results are supplemented by
data provided by Regenesis and other applications of the HRCŪ technology. Vendor's claims
regarding the effectiveness and applicability of the HRCŪ technology are included in Appendix
A.
4.1 FACTORS AFFECTING PERFORMANCE
Factors potentially affecting the performance of the HRCŪ technology include the following:
Waste contaminant types and characteristics
Site hydrogeologic characteristics, which affect how HRCŪ is introduced
into the aquifer
Operating parameters, including HRCŪ physical and chemical properties
and the aquifer's geochemistry and microbiology, all of which affect the
type and amount of HRCŪ needed to effectively treat contaminated
groundwater
Maintenance requirements, which are a function of the hydrogeologic
and operating parameters, will be a factor at sites requiring multiple
injections of HRCŪ
The following sections further discuss how these factors can potentially affect the HRCŪ
technology's performance.
4.1.1 Applicable Wastes
Release and fermentation of the lactic acid in HRCŪ yields hydrogen and produces a reductive,
anaerobic environment. As such, those contaminants most applicable to the technology are
typically electron acceptors and those susceptible to anaerobic, biotic, or abiotic reductive
degradation or transformation. According to Regenesis, HRCŪ can treat several of these types of
contaminants, including chlorinated solvents, nitroaromatics, inorganics, and heavy metals (see
Table 4-1). Most of these contaminants, especially organics, are treated through enhanced
biodegradation processes. However, abiotic processes aided by a conducive geochemistry can
serve as a secondary mechanism. According to Regenesis, the technology is most effective for
passive in situ treatment of dissolved-phase contaminants, but it can also be used for sorbed and
free-phase applications under proper conditions. In addition, the technology can be incorporated
into an active in situ bioremediation system employing extraction and reinjection of groundwater.
Such an approach can be used where surface features limit access to the aquifer, when hydraulic
control is needed or variable groundwater flow directions are encountered, or when the
contaminant concentrations necessitate longer treatment times.
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Table 4-1
Summary of Treatable Contaminants According to Regenesis
Contaminant Group HRCŪ
Chlorinated Ethenes
Perchloroethene XXX
Trichloroethene XXX
Dichloroethene XXX
Vinyl Chloride XXX
Chlorinated Ethanes
Trichloroethane XXX
Dichloroethane XXX
Chloroethane XXX
Chlorinated Methanes
Carbon Tetrachloride XX
Chloroform XX
Dichloromethane XX
Chloromethane XX
Chlorofluorocarbons XXX
Chlorinated Aromatics
Pesticides XXX
Chlorobenzenes XXX
Pentachlorophenol XX to XXX
Furans XXX
Nitroaromatics
Explosives XXX
Dyes XXX
Inorganics
Nitrate XXX
Perchlorate XXX
Heavy Metals
Chromium XXX
Arsenic XXX
RATING SCALE: XXX = Highly Effective, XX = Effective, and X= Partially
Effective
NOTE: Relative effectiveness can vary based on site conditions.
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4.1.2 Hydrogeologic Characteristics
Site hydrogeology significantly affects the performance of the HRCŪ technology by controlling
the following: (1) the implementability of the technology; (2) the selection of the type of HRCŪ
application (treating the entire groundwater plume or source [grid-based design], creating a
permeable hydrogen barrier to intercept a plume [barrier-based design], or treating the source area
after excavation); and (3) the HRCŪ injection technique (soils or bedrock setting). Hydrogeologic
characteristics that affect performance of the HRCŪ technology application are discussed further
in the following paragraphs.
Implementability
Implementation of the HRCŪ technology is directly affected by several hydrogeologic factors,
including the depth to the saturated zone, the types of soil or bedrock and their permeability, the
groundwater seepage velocity, and the saturated thickness of the contaminated aquifer.
The depth to the saturated zone can be a factor in determining the appropriate method for
emplacing HRCŪ into the subsurface. The most common method used to emplace HRCŪ into the
saturated zone is by direct-push technology. This method allows for direct contact with soils to
ensure that HRCŪ is injected into the formation. HRCŪ is typically injected from the bottom up
using commercially available high-pressure pumps (see Section 4.2.1). Injecting from the bottom
up is time-efficient and allows for monitoring of injection dose rates (pounds of HRCŪ injected
per foot of aquifer). However, most direct-push methods have depth-of-application limits and
typically cannot extend past 100 to 150 feet bgs, thereby limiting HRCŪ injection depths.
Another limiting factor of direct-push methods is refusal by subsurface materials containing large
gravel or cemented sediments. Relocation of injection points may be necessary when refusal
occurs.
Soil permeability can affect the type of injection method and the density of injection locations.
Tight, less permeable soils will require higher injection pressures. Low permeability conditions
may require a greater density of injection points due to the limited penetration of HRCŪ into the
formation. Higher penetration pressures for all soil types will also be encountered in deeper
applications as a result of greater overburden and hydrostatic heads.
Groundwater seepage velocity does not affect the injection method but can affect (1) the density
of injection points in a grid, or (2) the location and number of barriers needed to intercept
groundwater flow. Seepage velocity is also a design parameter that will affect HRCŪ dose rates
and longevity, and will need to be assessed prior to HRCŪ application. HRCŪ dose rates and
longevity are discussed further in Section 4.1.3.
Another critical factor to consider is the thickness of the saturated zone. Many chlorinated VOCs
are denser than water. When released in sufficient quantity, these dense nonaqueous-phase
liquids (DNAPL) will migrate down through the unsaturated and saturated zones under the
influence of gravity. If sufficient volumes of DNAPL have been released to the environment,
they will continue to migrate downward in an aquifer until an impermeable barrier stops further
downward migration. This process can result in dissolved contaminant being present several tens
to hundreds of feet bgs. For effective treatment, HRCŪ will need to be injected to ensure that
flow throughout the entire contaminated interval of the saturated zone is intercepted.
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Application to Treat an Entire Groundwater Plume: Grid-Based Design
In this application, HRCŪ is injected directly into the aquifer matrix in a grid pattern over the
horizontal extent and across the vertical zone of the contaminant plume or source area. The shape
of the area to be treated is determined primarily by the shape of the contaminant plume or source,
or by the accessible area within the plume or source. According to Regenesis, the technology is
most applicable to dissolved contaminants, but it can treat adsorbed and free-phase contaminants.
For source treatment application, the period of remediation will typically be extended to account
for the added mass transfer limitations imposed by the location or phase of the contaminants
(such as adsorbed or free-phase nonaqueous-phase liquids [NAPL]). Dissolved contaminants are
more readily available for the microbes to use. Adsorbed contaminants must desorb first or, by
chance, be adsorbed near active microbes. As dissolved contaminants are degraded, additional
contaminant will desorb from the soil surface to maintain equilibrium or diffuse from high
concentration areas to lower concentration areas as a result of increased concentration gradients.
This process can be slow and impeded further by diffusion limitations imposed not just near the
soil surface but also through the soil pores. An additional phenomenon that can aid degradation
of adsorbed contaminants is the secretion of bio-surfactants by microbes. These surfactants will
also aide the dissolution or solubilization of contaminants from soils.
Large pools of NAPL can limit HRCŪ application and can have toxic effects on microbes, which
can impede the biological degradation of NAPL. However, DNAPL often exists as dispersed
pockets of narrow ganglia, stringers, or small blobs resulting from residual free product that has
been trapped within the soil pores. Therefore, through phenomena similar to those described
above for adsorbed contaminants (shifts in surface-water partitioning, enhanced diffusion
gradients, and bio-surfactants), enhanced degradation will also occur in free product source areas.
When adsorbed or free-phase contamination exists, water concentrations of total VOCs may
actually increase after injection. This evidence for potential degradation of adsorbed and free-
phase contaminants has been observed in the field for chlorinated ethenes. Chlorinated ethenes
degrade through a sequential dechlorination process in which a parent contaminant such as PCE
degrades to TCE, cis-DCE, and vinyl chloride. The rate of anaerobic degradation decreases as
the ethene is dechlorinated. Therefore, concentrations of certain daughter products, cis-DCE in
particular, will increase and take longer to decay. Concentrations of cis-DCE have been observed
that exceed the original parent concentrations in groundwater, indicating that an additional source
of the parent compound exists as a separate phase.
The type of soils can further complicate the use of HRCŪ in source zones. Soils with a high
organic carbon content will adsorb more contaminant. However, these same soils already contain
a carbon food source that may make the use of other substrates unnecessary to achieve anaerobic
conditions. Highly porous, low permeability soils can retain more adsorbed-phase contaminants
and are typically regions where NAPL will collect. Consideration must be given to this
phenomenon both in terms of effects on injection pressures, dose rates, and remediation times.
Permeable Hydrogen Barrier Application: Barrier-Based Design
When a groundwater plume is large and an HRCŪ injection grid is not cost-effective, an
alternative approach is to use one or more HRCŪ barriers. HRCŪ barriers are installed
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perpendicular to the groundwater flow direction at one or more intervals throughout the length of
the plume. In this design approach, a unit volume of contaminated water moving in the plume is
subject to single or sequential doses of hydrogen to enhance or stimulate the reductive reactions
as the plume migrates.
As was demonstrated at the RMA site, HRCŪ is emplaced in one or more rows of injection points
to form an HRCŪ barrier, thereby creating an anaerobic treatment zone oriented to intercept the
downgradient migration of contaminants. In this application, the HRCŪ hydrogen barrier does
not form a solid wall or true "barrier", but rather a series of discrete HRCŪ injections that produce
the desired levels of dissolved hydrogen. The location of injection points in each row is
staggered with respect to points in other rows to minimize the effective spacing perpendicular to
groundwater flow. The HRCŪ technology under this application would be termed a permeable
reactive barrier; however, this approach does not require slurry walls or sheet piles to channel
groundwater through the reactive material. It is also not a barrier in which treatment is completed
once groundwater passes through. An anaerobic plume is generated downgradient from the
barrier; the size of which will be dependent on factors such as seepage velocity, microbial
population, and hydrogen demand (see Section 4.1.3). Degradation begins at the barrier and
continues to progress as groundwater and contaminants move downgradient. Therefore, the
barrier must be placed sufficiently upgradient from receptors or point-of-compliance wells.
As described above, the HRCŪ hydrogen barrier application involves placing a row of HRCŪ
injection points perpendicular to the plume flow direction. In areas of high groundwater velocity
or contaminant loading, multiple rows of injection points may be required to provide sufficient
contact time for the microbes to degrade the contaminants. HRCŪ barriers may also be
constructed in an iterative fashion so that injection point arrays are installed over time to satisfy
regulatory criteria, remediation budgets, and the overall environmental strategy for a given site.
HRCŪ barriers are typically directed toward containment of a contaminant or point of compliance
strategy and do not provide for source area remediation. If the contaminant source area is not
remediated, the HRCŪ barrier will need to be maintained over time through re-injection events or
combined with other treatment technologies.
Source Area Excavation Application
The HRCŪ excavation application provides for a hydrogen source across a large treatment area in
the bottom of an open excavation. This approach can be used in conjunction with source removal
actions where contaminated soil in a source area is excavated. This application is only effective
when excavation extends into the saturated zone. HRCŪ is emplaced directly into the bottom of
the excavation prior to backfilling to enhance or stimulate biodegradation of the remaining bound
and dissolved-phase contaminants in soil. However, this application will not treat dissolved-
phase contaminants that have migrated away from the source area.
Injection in Soils Setting
For soils, the most effective method to emplace HRCŪ into the subsurface is to inject the material
through direct-push rods using hydraulic equipment. This approach allows for relatively quick
distribution of HRCŪ throughout the aquifer. Soils with moderate to high permeability
characteristics (gravels and sands) and bounded by lower permeable soils (clays and silts) present
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the fewest obstacles and complications to HRCŪ application. The RMA site evaluation involved
treating a groundwater plume in unconsolidated soils with a lower boundary of claystone.
However, the penetration depths that can be achieved by direct-push technology limit this method
of product delivery.
Injection in Bedrock Setting
HRCŪ emplacement techniques in bedrock aquifers are dictated by the characteristics of the
aquifer and the bedrock. HRCŪ can be injected into cased or open-hole completed groundwater
wells using down-hole packers to isolate the injection interval or by backfilling the borehole with
a tremie pipe. The HRCŪ installation method should be a function of the bedrock aquifer
material type, the nature and distribution of fractures, and the potential radius of influence for the
HRCŪ away from the borehole.
The best emplacement conduit in a fractured bedrock aquifer is typically an open-hole
groundwater well. An open-hole well application allows HRCŪ to come into direct contact with
the bedrock fractures. This direct contact can be by tremie-backfill or packer-assisted
emplacement methods. If the bedrock matrix is sufficiently competent to support a packer, HRCŪ
can be injected into the treatment zone under pressure. To place HRCŪ into direct contact with
the fracture system under pressure, the operator must apply HRCŪ at a pressure that does not
exceed the inflation pressure of the down-hole packers. This method allows for application of
HRCŪ into defined sections of the aquifer; however, distribution of the HRCŪ is controlled in part
by the distribution, orientation, and interconnectedness of the fractures in the treatment zone.
When packers cannot be used, HRCŪ can be delivered by tremie backfill into an open-hole
completed groundwater well. This approach requires that the entire saturated section of the
borehole be backfilled with HRCŪ material. HRCŪ distribution is accomplished by gravity flow
of the material into the aquifer matrix. However, the viscous nature of the HRCŪ may limit
distribution of the material into some portions of the aquifer pore space.
In bedrock aquifers where open-hole completions are impossible or impractical, HRCŪ can be
applied through small diameter injection wells (2-inch). These injection wells are typically
completed at the surface to allow connection to a pump so HRCŪ can be injected under pressure.
Numerous wells may need to be installed to adequately distribute HRCŪ throughout the treatment
zone. This application could result in substantially higher remediation costs compared to the
other bedrock application techniques due to the number of wells that would be required to
adequately distribute the HRCŪ material.
4.1.3 Operating Parameters
Since HRCŪ is a time-released product, the required dose rate and longevity is a function of the
product chemistry and transport properties and certain biological and geochemical features of the
aquifer. According to Regenesis, HRCŪ has been shown to have a direct effect on microbial
populations through the release of lactic acid and subsequent production of secondary organic
acids. The physical and chemical characteristics of HRCŪ, and the effects of aquifer
geochemistry and microbiology on HRCŪ longevity and dose rates, are discussed in more detail
in the following paragraphs
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HRCŪ Physical and Chemical Characteristics
The "active ingredient" of HRCŪ, glycerol (tri) polylactate (GPL), is one of a family of
polylactate esters, defined by patent, that upon hydration break down to release lactic acid.
Structurally, an ester is the product of a reaction between an organic acid (COOH group) and an
alcohol (OH group). In this reaction, the two groups react, water drops out, and the ester link is
formed. Polylactate esters are formed from the combination of certain alcohols with a unique
lactic acid complex serving as the organic acid group. The alcohols are compounds such as
glycerol (3 OH groups), xylitol (5 OH groups), and sorbitol (6 OH groups). These "foundation"
molecules are then esterified with a polylactic acid complex. The unique feature of the polylactic
acid complex is that lactic acid is esterified to itself. This is possible because lactic acid has both
an OH and a COOH group. This reaction produces trimers or tetramers of lactic acid and creates
a "polylactic acid complex" or "polylactate complex," which is in turn esterified to the foundation
OH donor.
The exact chemical nature of a specific polylactate ester, such as GPL, is a major factor in
product longevity. The degree of complexity and esterification of the molecule control its
viscosity, which is a critical factor in reactivity. This in turn controls product longevity under a
given set of conditions. For example, the (tri)polylactate form of GPL would be more viscous
than the (di)polylactate form, and a molecule built with tetramers of lactic acid would be more
viscous than one made with trimers. Esters produced with longer chain alcohols such as sorbitol
will be more viscous than a glycerol polylactate ester because it is based on 6 carbons rather than
3 carbons. Viscosity becomes a dominant issue in longevity because it is a measurement of
resistance to flow. As a result, viscosity controls the speed at which HRCŪ becomes soluble in
water. Therefore, as a polylactate formulation breaks down it becomes less viscous, thus
exposing more of the compound to chemical and microbiological attack. Groundwater seepage
velocity is another physical design parameter affecting HRCŪ dissolution. The more pore
volumes that pass through the injected HRCŪ over a given time frame, the more HRCŪ will
dissolve.
Aquifer Microbiology
The nature and extent of microbial populations has a significant effect on the longevity of HRCŪ
(Farone, W.A., S.S. Koenigsberg and J. Hughes 1999). Most microbes, and not just the kinds that
ferment lactic acid into hydrogen or those that promote reductive dechlorination, will produce
esterases and Upases that degrade HRCŪ and release lactic acid. Therefore, if an aquifer has a
high microbial population, it will metabolize a given mass of HRCŪ at a faster rate than if the
microbial counts are moderate to low.
According to Regenesis, HRCŪ degrades slowly, on average, over about a 9-month period (as
modulated by certain features in the contaminated aquifer). Residual hydrogen will remain
present in the aquifer after the HRCŪ degrades. Biomass should continue to accumulate and be
available as fermentable carbon. Regenesis estimates the standard formulation of HRCŪ will
stimulate reductive dechlorination within the aquifer for at least 12 months following injection.
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Aquifer Geochemistry
Biodegradation is fundamentally an electron transfer process in which electrons are removed
from reduced compounds (electron donors) and transferred to more oxidized compounds
(electron acceptors); the energy released in the process is used by microbes to sustain metabolism
and growth. Like humans, microbes eat electron donors and breath electron acceptors. The most
energetically favorable electron acceptor is oxygen.
The concentrations of competing electron acceptors such as dissolved oxygen, nitrate, ferric iron,
and sulfate can have an effect on the dose rate and longevity of HRCŪ for enhancing in-situ
bioremediation. Hydrogen from HRCŪ is used to reduce these electron acceptors to create redox
conditions that are conducive to reductive dechlorination. As a result, the demand of these
various electron acceptors for hydrogen (and consequently HRCŪ) must be considered in the
specification of the amount of HRCŪ required for a project. Groundwater data indicating the
actual site values for these parameters are important in determining an accurate final design for
HRCŪ application.
4.1.4 Maintenance Requirements
Maintenance requirements for in situ HRCŪ treatment are minimal. After HRCŪ is injected into
the subsurface, there are no active maintenance requirements. Additional HRCŪ may need to be
injected to replace HRCŪ that has been used in the treatment reactions. The frequency at which
HRCŪ may need to be replaced is highly site-specific.
4.2 SITE CHARACTERISTICS AND SUPPORT REQUIREMENTS
Site-specific factors can affect application of the in situ HRCŪ technology, and these factors
should be considered before selecting the technology for remediation of a specific site. Site-
specific factors addressed in this section include site access, area, and preparation requirements;
climate; utility and peripheral supply requirements; support systems; and personnel requirements.
4.2.1 Site Access, Area, and Preparation Requirements
In addition to the hydrogeologic conditions that determine the HRCŪ technology's applicability
and design, other site characteristics affect implementation of this technology. The actual amount
of space required for an in situ system depends on the required depth to the contamination and the
number of HRCŪ injection points required for coverage of the treatment area.
The site must be accessible to and have sufficient operating and storage space for light- to
medium-duty construction equipment. Underground utilities crossing the path of the proposed
system may force modification of the HRCŪ injection field. Overhead space should be clear of
utility lines for direct-push technology and drilling equipment to operate. The HRCŪ injection
field may also need to be constructed around existing aboveground structures on site.
A positive displacement pump (such as a piston pump) that can meet the recommended minimum
pressure, displacement, and discharge requirements needed to successfully inject HRCŪ into the
subsurface will be required. According to Regenesis, the R.E. RUPE Company Model
ORC/HRC 9-1500 and the recently developed Geoprobe GS-2000 pumps meet the pressure and
volume requirements needed for HRCŪ injection. When injecting measured volumes of HRCŪ
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through probe boreholes, the installer should have a means to measure the HRC as it is pumped
into the subsurface.
Internal pump mechanisms and injection hoses should be cleaned by circulating hot water and a
biodegradable cleaner such as Simple GreenŪ. As a result, the installer must have a supply of
water and equipment to heat the water. In order to maintain optimal pumping conditions, pure
glycerin should be circulated through the pump after the pump has been thoroughly cleaned. A
small volume of glycerin should be left in the pump works and hopper during storage or shipping.
Further cleaning and decontamination (if necessary due to subsurface conditions) should be
performed according to the equipment supplier's standard procedures and any local regulatory
requirements.
4.2.2 Climate Requirements
The viscosity of HRCŪ is affected by temperature; as a result, the product must be warmed to a
working temperature (95 °F recommended) prior to pumping it into the ground. At RMA, the
product was stored inside a building overnight until it was used. The installation contractor used
a portable steam cleaner and a galvanized trough to heat the HRCŪ to the required temperature.
Extreme cold temperatures may necessitate additional handling, storage, emplacement
requirements, and equipment.
Aboveground equipment associated with sampling programs to monitor the effectiveness of the
HRCŪ injection may be affected by below freezing temperatures. At RMA, water samples were
collected from groundwater monitoring wells installed at the site. The samples were collected
with dedicated bladder pumps. Each pump was outfitted with a freeze protection device to
prevent sample water from freezing in the discharge tube.
4.2.3 Utility and Peripheral Supply Requirements
Existing on-site sources of power and water may facilitate construction activities. During
installation, water will be required to clean the injection system; however, this water can be
transported to the site if an on-site source does not exist. Portable electrical generators can be
used to supply electrical needs, if no power source exists on site. After the initial construction
phase, the HRCŪ system installed at the RMA site required no electrical power or other utility
support. For most applications, the wash water from the injection equipment is normally
disposed of through a municipal publicly owned treatment works after appropriate permits are
obtained.
Supply requirements specific to the technology may include additional HRCŪ for subsequent
injections. The frequency at which HRCŪ may need to be replaced is highly site-specific. Other
supplies indirectly related to the technology include typical groundwater sampling supplies and
equipment for use during system monitoring activities.
4.2.4 Required Support Systems
No pretreatment of groundwater is necessary for HRCŪ applications. The application of HRCŪ to
aquifers containing chlorinated ethene compounds may lead to the formation of vinyl chloride;
however, only as a transitional state as the dechlorination process proceeds the vinyl chloride will
eventually degrade to ethene. In cases where site conditions do not allow the vinyl chloride to
have an adequate residence time in contact with HRCŪ, it is possible that vinyl chloride could
move off-site without conversion to ethene. A second HRCŪ treatment application or other
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secondary treatment may need to be installed downgradient of the original HRCŪ injection area if
it is determined that further treatment is necessary.
4.2.5 Personnel Requirements
Personnel requirements for monitoring the HRCŪ system are minimal. Site personnel will be
required to collect periodic groundwater samples to evaluate system performance. Groundwater
should be analyzed at the site during sample collection for redox conditions, dissolved oxygen,
and pH. Some laboratory analyses require specialized sample preparation and handling
techniques. Field personnel should have skills and experience to prepare and handle these
samples and to generate these types of field data.
Personnel requirements for long-term maintenance will depend on the type of maintenance
activities. Personnel working with the system at a hazardous waste site may be required to
complete the training requirements under the Occupational Safety and Health Act (OSHA)
outlined in Title 29 of the Code of Federal Regulations 1910.120, which covers hazardous waste
operations and emergency response. Personnel may also be required to participate in a medical
monitoring program as specified under OSHA.
4.3 MATERIAL HANDLING REQUIREMENTS
HRCŪ has no special handling requirements from a health and safety standpoint. HRCŪ is a
polylactate ester that is a food-grade substance. In the subsurface environment, lactic acid
products are eventually completely removed either as methane or carbon dioxide and water,
leaving no residue.
HRCŪ is shipped in 4.25-gallon buckets and each bucket has a gross weight of approximately 32
pounds (net weight of HRCŪ is 30 pounds). At room temperature, HRCŪ is a sticky gel with a
viscosity of approximately 20,000 centipoises (roughly equivalent to cold honey). The HRCŪ
material has a nominal density of 1.3 grams per cubic centimeter or approximately 10.8 pounds
per gallon. The viscosity of HRCŪ is temperature sensitive, and it becomes viscous below the
manufacturer-recommended operating temperature. The temperature/viscosity relationship is
non-linear.
Regenesis recommends the following handling procedures:
HRCŪ should be stored in a warm, dry place that is protected from direct
sunlight
HRCŪ should be mixed into a relatively uniform fluid prior to injection
Product uniformity is most easily achieved by pre-heating the HRCŪ
material before pouring it into the pump hopper
Scrape any separated HRCŪ material from the bottom of each bucket
Field personnel should take the following precautions while handling and applying HRCŪ: (1) use
appropriate safety equipment, including eye and splash protection; (2) gloves should be used as
appropriate based on the exposure duration and field conditions; (3) field staff should review the
Material Safety Data Sheet that is provided with the shipment; and (4) personnel who operate
field equipment during the installation process should have appropriate training, supervision, and
experience with pressurized mechanical pump systems.
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4.4 TECHNOLOGY LIMITATIONS
Recent studies by Regenesis and others indicate that a broad range of contaminants may be
reduced by the HRCŪ technology in addition to chlorinated VOCs (see Table 4-1). Past studies
have shown that HRCŪ has been effective in reducing concentrations of petroleum hydrocarbons
(aliphatic and aromatic hydrocarbons), simple aromatics (benzene, toluene, ethylbenzene, and
xylene), polyaromatic hydrocarbons, certain classes of solvents (aldehydes, ketones, and
alcohols/phenols), and ethers (methyl tertiary butyl ether, and 1,4-dioxane) in groundwater. Sites
involving multiple types of groundwater contaminants may not be ideally suited for this
technology alone; however, it can be effective at sites where a treatment train approach is used
(such as sequential anaerobic/aerobic degradation barriers, air sparging, or soil vapor extraction).
4.5 POTENTIAL REGULATORY REQUIREMENTS
This section discusses regulatory requirements pertinent to using the HRCŪ technology at
Superfund, RCRA corrective action, and other cleanup sites. The regulations applicable to
implementation of this technology depend on site-specific remediation logistics and the type of
contaminant being treated; therefore, this section presents a general overview of the types of
federal regulations that may apply under various conditions. State and local requirements should
also be considered; because these requirements vary from state to state, they are not presented in
detail in this section. Table 4-2 summarizes the environmental laws and associated regulations
discussed in this section.
During the SITE evaluation of the HRCŪ technology at RMA, no groundwater was pumped to the
ground surface as a part of the installation or operation of the system. Groundwater was pumped
to the surface for sample collection as part of the evaluation, and the purge water was handled and
disposed of as waste. Purge water was handled and disposed of in accordance with federal and
state laws.
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Table 4-2
Summary of Environmental Regulations
Act/Authority
Comprehensive
Environmental
Response,
Compensation, and
Liability Act
(CERCLA)
Resource
Conservation and
Recovery Act
(RCRA)
Clean Water Act
(CWA)
Safe Drinking
Water Act
Clean Air Act
Atomic Energy Act
(AEA) and RCRA
Occupational
Safety and Health
Administration
(OSHA)
Underground
Injection Control
Applicability
Cleanups at
Superfund sites
Cleanups at
Superfund and
RCRA sites
Discharges to
surface water
bodies
Water discharges,
water reinjection,
and sole-source
aquifer and wellhead
protection
Air emissions from
stationary and
mobile sources
Mixed wastes
All remedial actions
Underground
Injections
Application to the HRC Technology
This program authorizes and regulates the
cleanup of releases of hazardous substances. It
applies to all CERCLA site cleanups and
requires that other environmental laws be
considered as appropriate to protect human
health and the environment.
RCRA regulates the transportation, treatment,
storage, and disposal of hazardous wastes.
RCRA also regulates corrective actions at
treatment, storage, and disposal facilities.
National Pollutant Discharge Elimination
System requirements of CWA apply to both
Superfund and RCRA sites where treated water
is discharged to surface water bodies.
Pretreatment standards apply to discharges to
publicly owned treatment works. These
regulations do not typically apply to in situ
technologies.
Maximum contaminant levels and contaminant
level goals should be considered when setting
water cleanup levels at RCRA corrective action
and Superfund sites. Sole sources and protected
wellhead water sources would be subject to their
respective control programs.
If volatile organic compound emissions occur or
hazardous air pollutants are of concern, these
standards may be applicable to ensure that use of
this technology does not degrade air quality.
State air program requirements also should be
considered.
AEA and RCRA requirements apply to the
treatment, storage, and disposal of mixed waste
containing both hazardous and radioactive
components. Office of Solid Waste and
Emergency Response and Department of Energy
directives provide guidance for addressing
mixed waste.
OSHA regulates on-site construction activities
and the health and safety of workers at
hazardous waste sites. Installation and operation
of the technology at Superfund or RCRA clean-
up sites must meet OSHA requirements.
These regulations govern injection of substances
into groundwater.
Citation
Title 40 of the Code
Federal Regulations
(CFR)part300
40 CFR parts 260 to
270
40 CFR parts 122 to
125, part 403
40 CFR parts 141 to
149
40 CFR parts 50,
60, 61, and 70
of
AEA (10 CFR part 60)
and RCRA (see above)
29 CFR parts 1900 to
1926
40 CFR part 144
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4.5.1 Comprehensive Environmental Response, Compensation, and Liability Act
The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), as
amended by the Superfund Amendment and Reauthorization Act (SARA), authorizes the federal
government to respond to releases of hazardous substances, pollutants, or contaminants that may
present an imminent and substantial danger to public health or welfare. CERCLA pertains to the
HRCŪ technology by governing the selection and application of remedial technologies at
Superfund sites. Remedial alternatives that significantly reduce the volume, toxicity, or mobility
of hazardous substances and provide long-term protection are preferred. Selected remedies must
also be cost effective, protective of human health and the environment, and must comply with
environmental regulations to protect human health and the environment during and after
remediation.
CERCLA requires identification and consideration of environmental requirements that are
ARARs for site remediation before implementation of a remedial technology at a Superfund site.
Subject to specific conditions, EPA allows ARARs to be waived in accordance with Section 121
of CERCLA. The conditions under which an ARAR may be waived are as follows:
An activity that does not achieve compliance with an ARAR, but is part
of a total remedial action that will achieve compliance (such as a removal
action)
An equivalent standard of performance can be achieved without
complying with an ARAR
Compliance with an ARAR will result in a greater risk to health and the
environment than will noncompliance
Compliance with an ARAR is technically impracticable
A state ARAR that has not been applied consistently
For fund-lead remedial actions, compliance with the ARAR will result in
expenditures that are not justifiable in terms of protecting public health
or welfare, given the needs for funds at other sites
The justification for a waiver must be clearly demonstrated (EPA 1988b). Off-site remediations
are ineligible for ARAR waivers, and all applicable substantive and administrative requirements
must be met.
Depending on the treatment application, post-treatment (secondary treatment) such as air sparging
or soil- vapor extraction may be used in conjunction with the HRCŪ technology. This particular
method of secondary treatment system would require air emissions and effluent discharge either
on or off site. CERCLA requires on-site discharges to meet all substantive state and federal
ARARs, such as effluent standards. Off-site discharges must comply not only with substantive
ARARs, but also state and federal administrative ARARs, such as permitting, designed to
facilitate implementation of the substantive requirements.
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4.5.2 Resource Conservation and Recovery Act
RCRA, as amended by the Hazardous and Solid Waste Amendments of 1984, regulates
management and disposal of municipal and industrial solid wastes. EPA and the states
implement and enforce RCRA and state regulations. Some of the RCRA Subtitle C (hazardous
waste) requirements under 40 CFR parts 264 and 265 may apply at CERCLA sites because
remedial actions generally involve treatment, storage, or disposal of hazardous waste. However,
RCRA requirements may be waived for CERCLA remediation sites, provided equivalent or more
stringent ARARs are followed.
Use of the HRCŪ technology may constitute a treatment as defined under RCRA regulations in 40
CFR part 260.10. Because treatment of a hazardous waste usually requires a permit under
RCRA, permitting requirements may apply if the HRCŪ technology is used to treat a listed or
characteristic hazardous waste. Regulations in 40 CFR part 264, subpart X, which regulate
hazardous waste treatment, storage, and disposal in miscellaneous units, may be relevant to the
HRCŪ process. Subpart X requires that in order to obtain a permit for treatment in miscellaneous
units, an environmental assessment must be conducted to demonstrate that the unit is designed,
operated, and closed in a manner that protects human health and the environment. Requirements
in 40 CFR part 265, subpart Q (Chemical, Physical, and Biological Treatment), could also apply.
Subpart Q includes requirements for waste analysis and trial tests. RCRA also contains special
standards for ignitable or reactive wastes, incompatible wastes, and special categories of waste
(40 CFR parts 264 and 265, subpart B). These standards may apply to the HRCŪ technology,
depending on the waste to be treated.
In the event the HRCŪ technology is used to treat contaminated liquids at a hazardous waste
treatment, storage, and disposal facility as part of a RCRA corrective action, regulations in 40
CFR part 264, subparts F and S may apply. These regulations include requirements for initiating
and conducting RCRA corrective actions, remediating groundwater, and operating corrective
action management units and temporary units associated with remediation operations. In states
authorized to implement RCRA, additional state regulations more stringent or broader in scope
than federal requirements must also be addressed.
Although not typically required, if secondary treatment is used in conjunction with the HRCŪ
technology, additional RCRA regulations may apply. If secondary treatment involves extraction
and treatment of groundwater, and the groundwater is classified as hazardous waste, the treated
groundwater must meet Land Disposal Restriction treatment standards (40 CFR part 268) before
reinjection or placement on the land (for example, in a surface impoundment).
RCRA parts 264 and 265, subparts AA, BB, and CC address air emissions from hazardous waste
treatment, storage, and disposal facilities. These regulations would not apply directly to the
HRCŪ technology, but may apply to the overall process if it incorporates secondary treatment,
such as air sparging or soil-vapor extraction. Subpart AA regulations apply to organic emissions
from process vents on certain types of hazardous waste treatment units. Subpart BB regulations
apply to fugitive emissions (equipment leaks) from hazardous waste treatment, storage, and
disposal facilities that treat waste containing organic concentrations of at least 10 percent by
weight. Many organic air emissions from hazardous waste tank systems, surface impoundments,
or containers will eventually be subject to the air emission regulations in 40 CFR parts 264 and
265, Subpart CC. Presently, EPA is deferring application of the Subpart CC standards to waste
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management units used solely to treat or store hazardous waste generated on site from remedial
activities required under RCRA corrective action or CERCLA response authorities (or similar
state remediation authorities). Therefore, Subpart CC regulations may not immediately affect
implementation of a secondary treatment technology associated with the HRCŪ technology used
in remedial applications. EPA may remove this deferral in the future.
4.5.3 Clean Water Act
The Clean Water Act (CWA) governs discharge of pollutants to navigable surface water bodies or
publicly owned treatment works (POTW) by providing for the establishment of federal, state, and
local discharge standards. On-site discharges to surface water bodies must meet substantive
National Pollutant Discharge Elimination System (NPDES) requirements, but do not require an
NPDES permit. A direct discharge of CERCLA wastewater qualifies as "on site" if the receiving
water body is in the area of contamination or in close proximity to the site, and if the discharge is
necessary to implement the response action. Off-site discharges to a surface water body require a
NPDES permit and must meet NPDES permit limits. Discharge to a POTW is considered an off-
site activity, even if an on-site sewer is used. Therefore, compliance with the substantive and
administrative requirements of the national pretreatment program is required. General
pretreatment regulations are included in 40 CFR Part 403. Any local or state requirements, such
as state anti-degradation requirements, must also be identified and satisfied.
Any applicable local or state requirements, such as local or state pretreatment requirements or
water quality standards (WQS), must also be identified and satisfied. State WQS are designed to
protect existing and attainable surface water uses (for example, recreational and public water
supply). WQSs include surface water use classifications and numerical or narrative standards
(including effluent toxicity standards, chemical-specific requirements, and bioassay requirements
to demonstrate no observable effect level from a discharge) (EPA 1988b). These standards
should be reviewed on a state- and location-specific basis before discharges are made to surface
water bodies.
Because the HRCŪ technology is deployed in situ and treats groundwater within the aquifer and
does not require groundwater extraction or discharge of effluent to surface water bodies or
POTWs, the CWA would not typically apply to the normal operation and use of this technology.
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4.5.4 Safe Drinking Water Act
The Safe Drinking Water Act (SOWA), as amended in 1986, required EPA to establish
regulations to protect human health from contaminants in drinking water. EPA has developed the
following programs to achieve this objective: (1) a drinking water standards program, (2) a UIC
program, and (3) sole-source aquifer and wellhead protection programs.
SDWA primary (health-based) and secondary (aesthetic) maximum contaminant levels generally
apply as clean-up standards for water that is, or may be, used as drinking water. In some cases,
such as when multiple contaminants are present, more stringent maximum contaminant level
goals may be appropriate. In other cases, alternate concentration limits (ACL) based on site-
specific conditions may be applied. CERCLA and RCRA standards and guidance should be used
in establishing ACLs (EPA 1987a).
The underground injection control program regulates water discharge through injection wells.
Injection wells are categorized as Classes I through V, depending on their construction and use.
Reinjection of treated water involves Class IV (reinjection) or Class V (recharge) wells and
should meet SDWA requirements for well construction, operation, and closure. The EPA or
states with approved UIC programs require a UIC permit to inject HRCŪ into an aquifer. At
RMA, a Class V UIC permit was required by EPA Region VIII for injection of HRCŪ during the
evaluation program and two tracer dyes (Uranine and Phloxine B) that were used to confirm
groundwater flow direction in the treatment area. Since HRCŪ is a food-grade substance that is
degraded by naturally occurring microorganisms and the two tracer dyes are considered non-
toxic, application for the injection permit presented no significant additional technical or
administrative requirements at the test site.
The sole-source aquifer and wellhead protection programs are designed to protect specific
drinking water supply sources. If such a source is to be remediated using the HRCŪ technology,
appropriate program officials should be notified, and any potential regulatory requirements
should be identified. State groundwater anti-degradation requirements and WQSs may also
apply.
4.5.5 Clean Air Act
The Clean Air Act (CAA), as amended in 1990, regulates stationary and mobile sources of air
emissions. CAA regulations are generally implemented through combined federal, state, and
local programs. The CAA includes pollutant-specific standards for major stationary sources that
would not be ARARs for the HRCŪ process, and would apply only if secondary treatment (such
as air sparging or soil-vapor extraction) were employed. State and local air programs have been
delegated significant air quality regulatory responsibilities, and some have developed programs to
regulate toxic air pollutants (EPA 1989). Therefore, state air programs should be consulted
regarding secondary treatment if used in conjunction with the HRCŪ technology.
4.5.6 Mixed Waste Regulations
Use of the HRCŪ technology at sites with radioactive contamination might involve treatment of
mixed waste. As defined by the Atomic Energy Act (AEA) and RCRA, mixed waste contains
both radioactive and hazardous waste components. Such waste is subject to the requirements of
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both acts. However, when application of both AEA and RCRA regulations results in a situation
that is inconsistent with the AEA (for example, an increased likelihood of radioactive exposure)
AEA requirements supersede RCRA requirements (EPA 1988a).
Office of Solid Waste and Emergency Response (OSWER), in conjunction with the Nuclear
Regulatory Commission (NRC), has issued several directives to assist in identification, treatment,
and disposal of low-level radioactive, mixed waste. Various OSWER directives include guidance
on defining, identifying, and disposing of commercial, mixed, low-level radioactive and
hazardous waste (EPA 1987b). If the HRCŪ technology is used to treat groundwater containing
low-level mixed waste, OSWER/NRC directives should be considered. If high-level mixed waste
or transuranic mixed waste is treated, internal DOE orders should be considered when developing
a protective remedy (DOE 1988). The SDWA and CWA also contain standards for maximum
allowable radioactivity levels in water supplies.
4.5.7 Occupational Safety and Health Act
OSHA regulations in 29 CFR Parts 1900 through 1926 are designed to protect worker health and
safety. Both Superfund and RCRA corrective actions must meet OSHA requirements,
particularly §1910.120, Hazardous Waste Operations and Emergency Response. Part 1926,
Safety and Health Regulations for Construction, applies to any on-site construction activities.
Any more stringent state or local requirements must also be met. In addition, health and safety
plans for site remediation projects should address chemicals of concern and include monitoring
practices to ensure that worker health and safety are maintained.
The HRCŪ technology does not require active operation by on-site personnel once installed.
Work activities involved with operating this technology are limited to peripheral activities such as
performance monitoring or periodic maintenance. All personnel involved in such activities are
required to complete an OSHA training course and must be familiar with all OSHA requirements
relevant to hazardous waste sites.
4.6 STATE AND COMMUNITY ACCEPTANCE
State regulatory agencies will likely be involved in most applications of the HRCŪ process at
hazardous waste sites. Local community agencies and citizen groups are often also actively
involved in decisions regarding remedial alternatives.
Because few long-term applications of the HRCŪ technology have been completed, limited
information is available to assess long-term state and community acceptance. However, state and
community acceptance of this technology is generally expected to be high, for several reasons:
(1) relative absence of intrusive surface structures that restrict use of the treatment area;
(2) absence of noise and air emissions; (3) the system is capable of significantly reducing
concentrations of hazardous substances in groundwater; and (4) the system generates no residual
wastes requiring off-site management and does not transfer waste to other media.
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5.0 TECHNOLOGY STATUS
The HRCŪ technology, developed by Regenesis, was first introduced in 1999 and is specifically
designed to supply a controlled release of hydrogen into the subsurface. Hydrogen in
groundwater is essential to a naturally occurring, microbially driven, anaerobic process known as
reductive dechlorination. The HRCŪ technology is currently available commercially and
Regenesis was granted a U.S. Patent for the product on July 16, 2002.
Regenesis will design HRCŪ systems to suit specific site needs and has developed a software to
provide assistance in estimating appropriate HRCŪ volumes and determining the proper design
for a bioremediation project. Designs for bioremediation projects focus on delivering HRCŪ into
contaminated groundwater plumes in grid-based or barrier-based configurations or a combination
of both. Design selection depends primarily on the size and shape of the plume, groundwater
velocity, site accessibility for injection equipment, and time frame for remediation.
Regenesis' HRCŪ technology has been applied to over 350 sites worldwide and makes up about
75 percent of all electron donor applications performed in the U.S. The technology's capabilities
with regard to removal of chlorinated contaminants have been demonstrated through bench-,
pilot-, and full-scale testing. According to Regenesis, the HRCŪ technology can also treat some
nitroaromatics (explosives and dyes), inorganics (nitrate and perchlorate), and heavy metals
(chromium and arsenic).
HRCŪ was recently proven as a low cost and effective remediation technology for the cleanup of
dry cleaner sites. The EPA sponsored state coalition for remediation of dry cleaner sites recently
published an article prepared by Florida's Department of Environmental Protection (FDEP) that
reports the cost effectiveness of using HRCŪ to treat groundwater contaminated with PCE as a
result of dry cleaning operations. The data presented in this article shows that a 96 percent
decrease in PCE contaminant mass was achieved at one site for approximately $28,000, which is
reportedly a fraction of the cost compared to other treatment options. FDEP's Bureau of
Petroleum Storage Systems subsequently deemed the HRCŪ technology as an environmentally
acceptable product for accelerated in situ bioremediation of groundwater at contaminated sites in
Florida.
The New Jersey Department of Environmental Protection (NJDEP) recently announced that
HRCŪ was the first innovative technology to be approved under a new state program designed to
promote brownfields development. An integral part of this endorsement was the evaluation of
HRCŪ as an effective, energy efficient and secondary pollution reducing site remediation
technology. An analysis prepared by NJDEP concluded that the use of HRCŪ as it relates to
energy issues is beneficial as its application only requires that it be injected into groundwater.
NJDEP reported that there is no permanent above-ground machinery, piping or equipment needed
and the absence of these elements precludes any major capital and energy expenditures beyond
the initial injection.
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The HRCŪ process is currently in operation at a Department of Energy environmental
management project in Ashtabula, Ohio. The site ground-water is contaminated with
radionuclides and other hazardous chemicals, including TCE. The installation consisted of
injecting HRCŪ into the saturated zone to speed the natural biodegradation of TCE into non-
hazardous end products. Recent studies completed by Argonne National Laboratories and
Northwestern University have shown that HRCŪ also facilitated biological reduction and
immobilization of radionuclides migrating out of the remediation zone at the Department of
Energy site.
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REFERENCES
American Public Health Association. 1998. Standard Methods for the Examination of Water and
Wastewater. American Water Works Association, and Water Environment Federation,
20th Edition.
Applied Power Concepts, Inc. 2000. Treatability Study - DIMP. April.
Evans, G. 1990. "Estimating Innovative Treatment Technology Costs for the SITE Program."
Journal of Air and Waste Management Association. Volume 40, Number 7. July.
Farone, W.A., S.S. Koenigsberg, and J. Hughes. 1999. "A Chemical Dynamics Model for CAH
Remediation with Polylactate Esters." In: A. Leeson and B.C. Alleman (Eds.), Engineered
Approaches for In Situ Bioremediation of Chlorinated Solvent Contamination, pp. 287-292.
Battelle Press, Columbus, OH.
Foster Wheeler Environmental Corporation. 1999. Rocky Mountain Arsenal - Long-Term
Monitoring Plan for Groundwater. December.
Tetra Tech. 200 la. Quality Assurance Project Plan for the Regenesis HRCŪ Technology
Evaluation at Rocky Mountain Arsenal. January 24.
Tetra Tech. 200 Ib. Addendum to Quality Assurance Project Plan for the Regenesis HRCŪ
Technology Evaluation at Rocky Mountain Arsenal. April 25.
U.S. Department of Energy. 1988. Radioactive Waste Management Order. DOE Order
5820.2A. September.
U.S. Environmental Protection Agency (EPA). 1979. Methods for Chemical Analysis of Water
and Wastes. EPA-600/4-79-020 and Subsequent EPA-600/4 Technical Additions.
Environmental Monitoring and Support Laboratory, Cincinnati, Ohio.
EPA. 1988a. Protocol for a Chemical Treatment Demonstration Plan. Hazardous Waste
Engineering Research Laboratory. Cincinnati, Ohio. April.
EPA. 1988b. CERCLA Compliance with Other Environmental Laws: Interim Final. OSWER.
EPA/540/G-89/006. August.
EPA. 1989. CERCLA Compliance with Other Laws Manual: Part II. Clean Air Act and Other
Environmental Statutes and State Requirements. OSWER. EPA/540/G-89-006. August.
EPA. 1991. Preparation Aids for the Development of Category II Quality Assurance Project
Plans. EPA/600/8-91/004. ORD.
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EPA. 1997. Test Methods for Evaluating Solid Waste, Physical/Chemical Methods, Laboratory
Manual, Volumes 1A through 1C, and Field Manual, Volume 2. SW-846, Third Edition, EPA
document control no. 955-001-00000-1 Office of Solid Waste. September.
EPA. 1999. Experimental Results for the Batch Adsorption/Oxidation Study - Rocky Mountain
Arsenal. November.
EPA and U.S. Army. 2000. Interim Response Action (IRA) Summary Report - Groundwater
Intercept and Treatment System North of Basin F. May.
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APPENDIX A
VENDOR'S CLAIMS FOR THE TECHNOLOGY
Note: information in this Appendix was obtained from Regenesis Bioremediation Products,
Inc. (Regenesis) website, http://www.regenesis.com, May 2003.
A.I Introduction
The HRCŪ technology can be used to degrade a range of chlorinated compounds in groundwater
including degreasing agents (PCE, TCE, TCA and their breakdown products) carbon
tetrachloride, chloroform, methylene chloride, certain pesticides/herbicides, perchlorate, nitrate,
nitroaromatic explosives and dyes, chlorofluorocarbons, certain metals, and radionuclides. The
technology, developed by Regenesis, has been successfully implemented at over 350 sites and
makes up about 75 percent of all electron donor applications performed in the U.S.
A.2 Technology Description
Regenesis' patented HRCŪ process is designed specifically for the treatment of chlorinated
solvent based contamination or any anaerobically degradable substance in the groundwater
environment. HRCŪ is a viscous liquid that is pressure injected directly into the subsurface.
Upon contact with water, HRCŪ slowly hydrolizes and is broken down by microbial action.
During this process, lactic acid is released and utilized by microbes to produce hydrogen. The
resulting hydrogen is then used in a microbial mediated process known as reductive
dechlorination. This step-by-step biodegradation process (reductive dechlorination) reduces
harmful contaminants into harmless compounds, such as ethene and ethane. Under the influence
of HRCŪ, this process may continue at an accelerated rate for up to 18 months.
A.3 Advantages of the Technology
The HRCŪ process has a number of advantages that make it uniquely suitable for use as a
treatment process for chlorinated compounds in groundwater. These advantages are briefly
described below.
Slow-release of lactic acid to support anaerobic microbial activity and produce hydrogen
in a range which is optimal for reductive dechlorination
Long-term source of lactic acid/hydrogen to the subsurface (up to 18 months)
Clean, low-cost, non-disruptive application
Not limited by presence of surface structures
No operations and maintenance following injection
Faster and often lower cost than drawn out natural attenuation
Complimentary product application design and site analysis from Regenesis
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A.4 HRC System Applications
There are two general designs (grid- or barrier-based configuration) for delivering HRCŪ into
contaminated groundwater plumes and selection is generally based on the size of the
contaminated plume, groundwater velocity, and required time frame for remediation. A third
application that is also sometimes used involves the emplacement of HRCŪ directly into the
bottom of an excavated area. This is typically applied to an area that has undergone a source
removal action and heavily contaminated soil has been removed via excavation and hauling.
HRCŪ will degrade any lingering source material and prevent recharge of groundwater
contaminants into the aquifer.
Grid-based designs are typically used for small- to medium-sized contaminant plumes where a
relatively short remediation period is desired. For this application, HRCŪ is injected into the
aquifer matrix in a grid pattern over the areal extent and across the vertical zone of the
contaminant plume. The shape of the area to be treated is determined primarily by the shape and
accessibility of the contaminant plume.
For very large plumes where a grid-based design is not cost effective, a barrier-based design is
typically applied. HRCŪ barriers are installed perpendicular to groundwater flow direction at
regular intervals throughout the length of the contaminant plume. In this approach, a unit volume
of water moving in the contaminant plume is subject to sequential doses of hydrogen to promote
reductive dechlorination reactions.
A.5 HRCŪ Design Considerations
There are a number of factors that need to be determined prior to implementing a grid- or barrier-
based design for a specific project. Regenesis has developed an HRCŪ design software to assist
experienced environmental professionals in the proper design of accelerated
attenuation/bioremediation projects. As with any remediation design, the first step is to gather
relevant site assessment data including lithologic data, contaminant concentrations, extent of
impacted groundwater, aquifer redox conditions, and groundwater velocity to determine which
design is more appropriate for the project. The next step is to determine the scope of the
remediation. After evaluating site-specific remediation strategies including health risks,
groundwater quality thresholds, and regulatory criteria, the remediation design is developed and
constructed.
The quantity of HRCŪ needed to fuel the reductive dechlorination process is estimated using the
site assessment data and general design guidelines. The HRCŪ design process is simplified by
using the HRCŪ Grid or Barrier Design Worksheets found on the HRCŪ Application Software
(available from Regenesis) and consists of specifying the following design variables:
1) Site Information: plume dimensions, aquifer transport parameters, and contaminant and
competing electron acceptor concentrations.
2) Demand Factors: microbial demand factor required for remediation of a source area or plume
cutoff (3x is typically used for treating a contaminant source with one application of HRC ; a
demand factor of 3x and an additional 2x is typically selected for a barrier application since the
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majority of contaminant load comes from flow into the barrier as opposed to potential sorbed or
residual phase in a source area).
3) HRCŪ Delivery Point Spacing: a delivery point spacing of 5 to 15 feet-on-center is typically
used to provide a reasonable distribution of HRCŪ into the contaminant plume. Spacing
specification depends primarily on groundwater velocity, sediment permeability, amount of
HRCŪ required, and HRCŪ grid or barrier size.
4) HRC Injection Rate: the HRCŪ injection rate for each point typically ranges from 4 to 10
pounds/foot, and its specification depends on the contaminant and competing electron acceptor
loading rate, competing microbial demand, and soil type.
A.6 Recommended Groundwater Monitoring Program for HRCŪ Pilot/Full Scale
Application
Monitoring of selected wells should be conducted to validate the HRCŪ-based enhancement of
reductive dechlorination processes. The monitoring well network would ideally include wells
from the following locations:
1) Inside Treatment Area: provides information on geochemical conditions and contaminant
trends induced by the HRC process.
2) Downgradient of Treatment Area: provides information on residence time effects. Since the
contaminant has to be in contact with the electron donor for a given length of time, the actual
performance may be evident at downgradient locations for sites with moderate to high
groundwater velocities.
3) Upgradient of Treatment Area: provides a measure of contaminant mass and competing
electron acceptor load entering treatment area.
4) Background: allows comparison of geochemical changes induced by addition of HRCŪ. An
initial or "baseline" round of sampling should be performed to determine pre-treatment
groundwater conditions. After application of HRCŪ, samples should be collected every other
month for a six to eight month period. After the initial biodegradation and geochemical trends
have been determined, the monitoring frequency can be decreased to a quarterly, semiannual, or
annual program.
Groundwater monitoring should be conducted using standard low flow groundwater sampling
techniques and include the measurement of the following field/chemical parameters:
All Relevant Contaminants
Field Parameters: DO, ORP, pH, temperature, and ferrous iron (optional field
measurement)
Natural Attenuation/Inorganic Parameters: dissolved iron and manganese, nitrate,
sulfate, sulfide, chloride, and alkalinity
HRC-Based Electron Donor: total organic carbon and metabolic acids (lactic, pyruvic,
acetic, propionic, and butyric)
End-Product Dissolved Gases: carbon dioxide, methane, ethane and ethene
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A qualified laboratory should conduct the analytical testing for metabolic acids, otherwise most
laboratories can provide testing for the remaining parameters. A typical cost for the above testing
program is approximately $300 per sample.
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