Cost and Performance Report
In Situ Anaerobic Bioremediation
Pinellas Northeast Site
Largo, Florida
Innovative Treatment
Remediation Demonstration
U.S. Department of Energy
April 1998
-------
This report was prepared for the U.S. Department of Energy by:
Sandia National Laboratories, Albuquerque, New Mexico; and
Hazardous Waste Remedial Actions Program, Oak Ridge, Tennessee.
For more information, please contact
Mike Hightower, Sandia National Laboratories, at (505) 844-5499.
-------
TECHNICAL REPORT DATA
ii inn mum iiiiii in
1. REPORT NO.
EPA 600/R-98/115
2.
3.
iiiiiiiiiiiiiiiiiiiiiiii
PB98-168008
4. TITLE AND SUBTITLE
COST AND PERFORMANCE REPORT; in SITU ANAEROBIC BIOREMEDIATION
PINELLAS NORTHEAST SITE, LARGO, FLORIDA
5. REPORT DATE
April 1998
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
REPORT VALIDATED BY: 'Davis S. Ingle, 2Mika Hightower,
and 3Guy W. Sewell
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
XER Program Manager; U.S. Dept of Energy; Grand Junctin Office
technical Coordinator; Innovative Treatment Remediation Demonstration
Program; Sandia Natinal Laboratories; Albuquerque, NM
3U.S. EPA; 919 Kerr Research Drive; Ada, OK
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
in-House j Collaborative
Effort.
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. EPA
NATIONAL RISK MANAGEMENT RESEARCH LABORATORY
SUBSURFACE PROTECTION AND REMEDIATION DIVISION
P.O. BOX 1198; ADA, OK 74820
13. TYPE OF REPORT AND PERIOD COVERED
Final Report
14. SPONSORING AGENCY CODE
EPA/600/15
15. SUPPLEMENTARY NOTES
PROJECT OFFICER: Guy W. Sewell 580-436-8566
16. ABSTRACT
The ITRD public/private partnership has conducted a pilot field demonstration of reductive anaerobic biological in-situ treatment technologies (RABITT) to evaluate its use as a standard
remedial technology for chloroethene contamination. System design scenarios were evaluated with respect to well configurations for delivery of these solutions and potential travel times of
injected solutions through contaminated zones. A site specific three-dimensional ground-water flow model was developed with these data and used to screen various injection and extraction
scenarios. Potential designs that did not provide sufficient transport of injected solutions through target zones, which included materials with relatively low hydraulic conductivity, in
approximately a 100 day time frame were excluded from consideration. The design chosen for the pilot study used an induced vertical flow design which incorporated infiltration galleries
and horizontal injection/extraction wells for fluid circulation.
Operational performance evaluation included evaluating delivery, and mixing of delivered electron donor, through the use of a 3D grid of sample drive points and the incorporation of
multiple tracers into the nutrient delivery mixture. Concurrent with system operation, determinations of metabolic daughter- and end-products were used evaluate the delivery strategy and
nutrient balance. Concentrations of parent contamianats were measured in extracted recirculation water and in descret multi level sample points.
At monitoring points where nutrient breakthrough was observed, significant declines in total chlorinated VOC concentrations (70-99%) were generally observed. For those wells where
electron donor arrival was not observed, generally in areas of lower permeability or in perimeter wells, only modest contaminant reductions were recorded. Degradation rates as high as 1-2
ppm per day were observed in higher concentration areas, while in areas with lower concentrations degradation rates ranging from 0.05 to 0.10 ppm per day were observed. There was little
evidence of significant daughter product buildup at monitoring wells after tracer breakthrough.
The cost of the pilot system totaled approximately $400,000, with over half the costs associated with sampling and analyses. System construction costs were about S90,000, while operating
costs were about S30.000 or SO. 12 per gallon of water treated. The extensive modeling, hydrogeologic, nutrient transport, and operating cost data developed during this pilot system operation
suggest that the Northeast Site could be remediated using nutrient injection in approximately 2-3 years at a cost of about S4-6M. From the results of the pilot study, nutrient addition to
stimulate in situ anaerobic biological degradation of chlorinated solvent contaminated soil and ground water appears to be a feasible and cost-effective remediation approach at the Pinellas
Northeast Site for areas with moderate contaminantion levels. The limiting factors for successful, cost effective implementation include the ability to deliver appropriate nutrients to all
contaminated areas, and hydraulic travel times.
17 . KEY WORDS AND DOCUMENT ANALYSIS
A. DESCRIPTORS
B. IDENTIFIERS/OPEN ENDED TERMS
C. COSATI FIELD, GROUP
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (THIS REPORT)
UNCLASSIFIED
21. NO. OF PAGES , _
40
20. SECURITY CLASS (THIS PAGE)
UNCLASSIFIED
22. PRICE
EPA FORM 2220-1 (REV. 4-77) PREVIOUS EDITION IS OBSOLETE
-------
CONTENTS
ACRONYMS iv
FOREWORD v
1. SUMMARY 1
2. SITE INFORMATION 2
3. MATRIX AND CONTAMINANT DESCRIPTION 4
4. TECHNOLOGY DESCRIPTION 7
5. IN SITU ANAEROBIC BIOREMEDIATION SYSTEM PERFORMANCE 15
6. IN SITU ANAEROBIC BIOREMEDIATION SYSTEM COSTS 26
7. REGULATORY/INSTITUTIONAL ISSUES 28
8. SCHEDULE 28
9. OBSERVATIONS AND LESSONS LEARNED 29
10. REFERENCES 30
11. VALIDATION 31
LIST OF FIGURES
Figure 1. Pinellas STAR Center location 2
Figure 2. Geologic section at the Pinellas STAR Center 4
Figure 3. Total VOCs in ground water 5
Figure 4. Map of the Pinellas bioremediation treatment area 10
Figure 5. Cross-section of treatment area looking West 11
Figure 6. MODFLOW model of system ground water flow patterns and transit times 12
Figure 7. Bioremediation pilot system process diagram 13
Figure 8. Contaminant monitoring data for well points 2D and 4B 20
Figure 9. Contaminant monitoring data for Level A and B Wells 22
Figure 10. Contaminant monitoring data for Level C and D Wells 23
Figure 11. Continuous monitoring data of the extracted ground water 24
Figure 12. Bioremediation project schedule 28
LIST OF TABLES
Table 1. Pre-treatment concentrations of contaminants 6
Table 2. Matrix characteristics affecting treatment cost or performance 6
Table 3. Operating characteristics affecting treatment cost or performance 14
Table 4. Pre and post-treatment monitoring well contaminant concentrations 16
Table 5. Bioremediation system performance summary 25
Table 6. Bioremediation project costs by interagency work breakdown structure 26
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation i i i
-------
CMS
COC
DCE
DOE
EPA
ER
FDEP
GC
GJO
HSWA
ICM
ITRD
kg
LMSC
MC
MSL
mg/L
mmol/L
M9/L
ppb
PPm
RCRA
RFA
RFI
SWMU
TCE
TOL
VC
VOC
LIST OF ACRONYMS
Corrective Measures Study
contaminant of concern
dichloroethylene
Department of Energy
Environmental Protection Agency
Environmental Restoration
Florida Department of Environmental Protection
gas chromatograph
Grand Junction Office
Hazardous and Solid Waste Amendments
Interim Corrective Measure
Innovative Treatment Remediation Demonstration
kilogram
Lockheed Martin Specialty Components
methylene chloride
mean sea level
milligrams per liter
millimoles per liter
micrograms per liter
parts per billion
parts per million
Resource Conservation and Recovery Act
RCRA Facility Assessment
RCRA Facility Investigation
Solid Waste Management Unit
trichloroethylene
toluene
vinyl chloride
volatile organic compound
iv
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
-------
FOREWORD
The Department of Energy (DOE) is working to accelerate the acceptance and application of innovative
technologies that improve the way the nation manages its environmental remediation problems. The DOE
Office of Environmental Restoration (EM-40) established the Innovative Treatment Remediation
Demonstration (ITRD) Program to help accelerate the adoption and implementation of new and innovative
soil and ground water remediation technologies. Developed as a public-private partnership in cooperation
with Clean Sites Inc., the U.S. Environmental Protection Agency (EPA) Technology Innovation Office, and
Sandia National Laboratories, the ITRD Program attempts to reduce many of the classic barriers to the
use of new technologies by involving government, industry, and regulatory agencies in the assessment,
implementation, and validation of innovative technologies.
The ITRD Program is an operational testing and evaluation program that assists DOE facilities in
identifying and evaluating innovative technologies that can remediate their sites in the most cost-effective
and responsible manner. The technologies considered for evaluation lack the cost and performance
information that would otherwise permit their full consideration as remedial alternatives. The technologies
have often shown promise in bench- or small-scale applications but have limited pilot or full-scale
operational performance data.
Funding is provided through the ITRD Program to assist participating site managers in identifying,
evaluating, implementing, and monitoring innovative technologies. The program provides technical
assistance to the participating DOE sites by coordinating DOE, EPA, industry, and regulatory participation
in each project; providing funds for site-specific treatability and pilot studies for optimizing full-scale
operating parameters; coordinating technology performance monitoring; and by developing cost and
performance reports on the technology applications.
In September 1993, the ITRD Program initiated a project at the Pinellas STAR Center (formerly the U.S.
Department of Energy Pinellas Plant) in Largo, Florida. The Pinellas Northeast Site Project is
characterized by chlorinated volatile organic compound (VOC) contamination of ground water and soil in a
shallow, sandy, surficial aquifer. Advisory groups composed of DOE, EPA, industry, and state and federal
regulatory representatives worked with the site Environmental Restoration (ER) Program to review and
evaluate approximately 20 potentially applicable innovative remediation technologies that could enhance
the cost or performance of a proposed baseline pump-and-treat system. Based on this technology review
and associated treatability studies, the Pinellas ER Program selected three technologies for possible
implementation, with final application to be based on the results of site-specific pilot-scale testing.
One of the technologies selected was in situ anaerobic bioremediation with nutrient circulation through
surface infiltration trenches and two horizontal wells (one injection, one extraction). The purpose of this
Cost and Performance Report is to document these pilot activities, present summary data, and provide
evaluation results on the cost and performance of this in situ anaerobic bioremediation system.
Participants involved in the assessment and evaluation of this technology included: regulatory
representatives from the Florida Department of Environmental Protection (FDEP) and EPA Region IV,
DOE representatives from Sandia and Oak Ridge National Laboratories; EPA representatives from the
Technology Innovation Office, Office of Federal Facility Enforcement, Superfund Innovative Technology
Evaluation Program, and R.S. Kerr Laboratory; and industry representatives from Lockheed Martin
Specialty Components, Phillips Petroleum, Exxon, General Electric, DuPont, Occidental Chemical,
Envirogen, Beak International, and Pelorus Environmental.
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
v
-------
1. SUMMARY
In early 1997, the Innovative Treatment Remediation Demonstration (ITRD Program conducted a pilot
study at the Pinellas STAR Center's Northeast Site to treat chlorinated volatile organic compounds (VOC)
using in situ anaerobic bioremediation. The Northeast Site is characterized by VOC contamination of a
shallow, sandy, surficial aquifer. Monitoring data indicate that some biodegradation of these contaminants
is already occurring at the site. The two primary objectives of this pilot study were to 1) evaluate the use of
nutrient injection to enhance in situ anaerobic biological degradation of chlorinated VOCs in areas of
moderate contaminant concentrations and 2) obtain operating and performance data to optimize the design
and operation of a full-scale system. During the short operational period of this pilot study, there was no
emphasis on reducing any contaminants to a specific regulatory level.
The pilot system was located in an area of the site that had total chlorinated contaminant concentrations in
ground water generally ranging from 10-400 ppm, with one monitoring well having concentrations in excess
of 2900 ppm. The bioremediation pilot system consisted of three 8-ft deep gravel-filled, surface infiltration
trenches and two 240-ft long horizontal wells with 30-ft screened intervals. The horizontal wells, directly
underlying and parallel to the middle surface trench, were at 16- and 26-ft depths. The study area was
about 45 feet by 45 feet and extended from the surface down to a thick, clay confining layer 30 feet below
the surface. Ground water was extracted from the upper horizontal well and recirculated via the surface
trenches and the lower horizontal well while benzoate, lactate, and methanol were added to the
recirculated water to serve as nutrients for the dechlorinating bacteria. The nutrient concentrations were
selected based on an earlier laboratory treatment study conducted through the ITRD Program. To assess
hydraulic flow characteristics and nutrient delivery, a bromide tracer was added to the water recirculated
through the deep horizontal well and an iodide tracer was added to the water fed to the surface trenches.
VOC, tracer, and nutrient concentrations were monitored biweekly at 16 well clusters (each with 4 vertically
discrete sampling intervals) spaced throughout the treatment area. VOC concentrations were also
continuously monitored in the extracted ground water.
The system operated from February 7, 1997 to June 30, 1997. During this period, ground water was
extracted and recirculated at a rate of about 1.5 gpm. Approximately 250,000 gallons of water, or based
on soil porosity about two pore volumes, were circulated during the pilot study. Tracer and nutrient
monitoring data indicated that nutrients were delivered to 90% of the central treatment area during
operations. Where nutrient breakthrough was observed, significant declines in total chlorinated VOC
concentrations (70-99%) were generally observed. These values correlate well with the results observed
from the extraction well. For those wells where nutrient arrival was not observed, generally in areas of
lower permeability or perimeter wells, only modest contaminant reductions were recorded. Degradation
rates of as high as 1-2 ppm per day were observed in higher concentration areas, greater than 100 ppm,
while in areas with lower concentrations degradation rates of 0.05 to 0.10 ppm per day were observed.
There was no evidence of significant degradation product build-up in any monitoring well, and many wells
with contaminant concentrations below 10 ppm showed contaminant reductions to regulatory allowable
levels.
The cost of the pilot system totaled approximately $400,000, with over half the costs associated with
sampling and analyses. Most of the sampling and analyses were discretionary and were used to verify the
system concept and design. This level of sampling would not be needed during a full-scale bioremediation
project. System construction costs were about $90,000, while operating costs were about $30,000 or
$0.12 per gallon of water treated. The extensive modeling, hydrogeologic, nutrient transport, and operating
cost data developed during this pilot system operation suggest that the Northeast Site could be remediated
using nutrient injection in approximately 2-3 years at a cost of about $4-6M. From the results of the pilot
study, nutrient addition to stimulate existing in situ anaerobic biological degradation of chlorinated solvent
contaminated soil and ground water appears to be a feasible and cost effective remediation approach at
the Pinellas Northeast Site for areas of moderate contaminant levels.
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
1
-------
2. SITE INFORMATION
,
Identifying Information
Facility.
Location:
OU/SWMU:
Regulatory Driver:
Type of Action:
Technology:
Period of operation:
Treatment volume:
Pinellas Science, Technology, and Research (STAR) Center,
formerly the U.S. Department of Energy Pinellas Plant
Largo, Pinellas County, Florida
Northeast Site
RCRA
ITRD Technology Demonstration
In situ anaerobic bioremediation
February 1997 to July 1997
45 ft x 45 ft x30 ft (60750 ft3)
Site Background
The Pinellas STAR Center occupies
approximately 100 acres in Pinellas
County, Florida, which is situated along the
west central coastline of Florida (Figure 1).
The plant site is centrally located within
the county, and is bordered on the north by
a light industrial area, to the south and east
by arterial roads, and to the west by
railroad tracks. The topographic elevation
of the Pinellas STAR Center site varies
only slightly, ranging from 16 feet MSL in
the southeast corner to 20 feet MSL in the
western portion of the site. Pinellas
County has a subtropical climate with
abundant rainfall, particularly during the
summer months.
The Northeast Site includes the East Pond
and is located in the northeast portion of
the Pinellas STAR Center site. The
Northeast Site is covered with introduced
landscaping grass and contains no
permanent buildings. The site contains
approximately 6 acres and is generally flat,
with slight elevation changes near the
pond. Access to the Northeast Site is
restricted and protected by fencing.
Site History
Florida
(Clecrwafer
Old Taropc Boy
¦Bryan
Dairy
PINELLAS
PLANT
Tampa Bay
Gulf of
Mexico
Figure 1. Pinellas STAR Center location.
The Pinellas Plant operated from 1956 to 1994, manufacturing neutron generators and other electronic and
mechanical components for nuclear weapons under contract to the U.S. Department of Energy and its
predecessor agencies (SIC Code 9631 A-Department of Energy Activities).
2
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
-------
The Northeast Site is associated with the location of a former waste solvent staging and storage area.
From the late 1950s to the late 1960s, before construction of the East Pond, an existing swampy area at
the site was used to dispose of drums of waste and construction debris. The East Pond was excavated in
1968 as a borrow pit. In 1986, an expansion of the East Pond was initiated to create additional storm
water retention capacity. Excavation activities ceased when contamination was detected directly west of
the East Pond.
The Northeast Site was identified as a Solid Waste Management Unit (SWMU) in a RCRA Facility
Assessment (RFA)1 conducted by EPA Region IV. Subsequently, a RCRA Facility Investigation (RFI)2 was
completed and approved in compliance with the facility's Hazardous and Solid Waste Amendments of 1984
(HSWA) permit.3
An Interim Corrective Measures (ICM) Study4 was developed and submitted to EPA for approval. EPA
issued final approval of the ICM in October 1991, and an interim ground water recovery system for the
Northeast Site was installed and commenced operation in January 1992. A Corrective Measures Study
Report was submitted to EPA in March 1993 and approved in November 19945. A Corrective Measures
Implementation Plan was submitted to EPA in March 1996 and approved in June 1996. The current
system now consists of seven ground water recovery wells equipped with pneumatic recovery pumps that
transfer ground water for temporary storage in a holding tank prior to being pumped to a ground water
treatment system.
Release Characteristics
The primary management practice that contributed to contamination at this site was the storage of
drums/containers. Because the site was used in the 1950s and 1960s for staging and burial of
construction debris and drums, some of which contained solvents, contamination at the Northeast Site is
believed to be the result of leakage of solvents or resins from those drums. The Pinellas Northeast Site
consists of a shallow ground water aquifer contaminated with a variety of VOCs, including chlorinated
solvents such as trichloroethylene, methylene chloride, dichloroethylene, and vinyl chloride. A recent
debris removal activity at the site removed multiple buried drums, many of which were empty but contained
solvent residue. The ongoing ICM system (pump and treat with air stripping) continues to recover
contaminants from the site and has been successful in preventing off-site migration of VOCs.
Site Contacts
Site management is provided by the DOE Grand Junction Office (DOE/GJO). The DOE/GJO Pinellas
STAR Center Environmental Restoration Program Manager is David Ingle [(813)-541 -8943]. The technical
contact for the Pinellas in situ anaerobic bioremediation project is Mike Hightower, the ITRD technical
coordinator at Sandia National Laboratories [(505)-844-5499],
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
-------
Wm 3. MATRIX AND CONTAMINANT DESCRIPTION
The anaerobic bioremediation system treated a matrix of soil and ground water to enhance the degradation
of chlorinated organic compounds (in situ).
Site Geology/Hydrology
Based on analysis of soil borings, details of well construction, and environmental studies at the Pinellas
STAR Center, the thickness of the surficial deposit below the site ranges from 25 to 35 feet and is primarily
composed of silty sand. Figure 2 shows the primary geologic units at the site. The top of the Hawthorn
Group (composed primarily of clay) is encountered at depths approximately 30 feet below ground surface.
The thickness of the Hawthorn Group ranges from 60 to 70 feet. The water table at the Northeast Site is
generally 3 to 4 feet below the ground surface. The ground water gradient and ground water flow velocity
at the site are both very low.
The ground water system at the
Pinellas STAR Center is composed of
three primary units: (1) an upper unit,
the surficial aquifer; (2) an intermediate
confining unit, the undifferentiated
portion of the Hawthorn Group; and
(3) a lower unit, the Floridan aquifer.
Undifferentiated sediments lie below
the surficial aquifer and above the
Floridan aquifer in Pinellas County.
Because of the low permeability of
these sediments in this region, these
upper sediments are not considered
part of the intermediate aquifer system
and are generally considered to be a
confining unit in the area of the
Pinellas STAR Center.
Measurements performed in the
bioremediation study area, including
down-hole flowmeter tests, have
suggested that the surficial aquifer in
the study area is relatively
heterogeneous with regard to hydraulic
conductivity. These heterogeneities
appear in the vertical and horizontal
direction. Specifically, zones of
reduced (i.e., by a factor of 10 or
greater) hydraulic conductivity occur at
depths between 10 to 14 feet and 22 to
27 feet. The bulk of the contamination
in the bioremediation study area has
been detected within these low
permeability layers.
Cross Section olong Longitude 82'45'
Pinellas Plant
2TS2-30"
Upper
Fioridon
Aquifer
O' M
<0 " f „ 0
„ "Q «,'1: J..- 0
^ J" V ^ % * * *
-------
Nature and Extent of Contamination
The primary contaminant group that the in situ bioremediation technology was designed to treat in this
application was chlorinated VOCs at the Northeast Site in the surficial aquifer. Contaminants of concern
(COCs) detected in Northeast Site ground water include 1,1-dichloroethane, 1,1-dichloroethylene,
benzene, ethylbenzene, 1,2-dichloroethylene (DCE) (cis and trans isomers), methylene chloride, toluene,
trichloroethylene (TCE), tetrachloroethylene, methyl tert-butyl ether, vinyl chloride, xylenes, and
chloromethane. The major contaminants of concern at this site, because of their concentrations and
cleanup levels are methylene chloride, cis 1,2-DCE, TCE, toluene, and vinyl chloride. Figure 3 shows a
contour map of VOC contamination in the ground water at the Northeast Site and in the area selected for
the bioremediation pilot-study. The concentrations prior to treatment and the solubilities of the primary
COCs within the selected bioremediation treatment area are summarized in Table 1.
There is some evidence that non-aqueous phase liquid contamination may be present in localized areas at
the Northeast site. VOC concentrations for several COCs exceeded solubility limits in some of the ground
water samples taken at the site, and the contaminant release scenario (leakage of solvents or resins from
drums stored or buried at the site) is consisent with this type of contamination. While the exact extent and
nature of this contaminant phase are unknown, these areas can provide continuing sources of ground
water contamination unless effectively addressed in a comprehensive, site remediation system design.
CD
DO
East
Pond
100
Scole In Feet
y in situ bioremediation
^ treatment area
Figure 3. Total VOCs in ground water (in jjg/L).
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
5
-------
Table 1. Pretreatment concentrations of contaminants.
Contaminant
Ground water
Solubility limit
(jjg/L)@20-25°C
Max. conc. (pg/L)
Avg. conc. (jjg/L)
TCE
1,700,000
46,600
1,100,000
Toluene
2,200,000
45,600
515,000
cis-1,2-DCE
210,000
19,200
800,000
Methylene chloride
760,000
18,450
16,700,000
Vinyl chloride
130,000
9,500
1,100-1,100,000
Hi Matrix Description and Characteristics
The surficial aquifer at this site consists predominantly of saturated beach-type silty sands (see Table 2). A
few lenses of more silty materials exist, though no clay lenses occur in the soil being treated. For these
soils, the hydraulic conductivities in the horizontal direction range from 10~3 to 10~5 cm/sec, while the
vertical conductivities are approximately 10-100 times lower. The surficial aquifer is highly anaerobic as
demonstrated by the dissolved oxygen and Eh values shown in Table 2.
Table 2. Matrix characteristics affecting treatment
cost or performance.
Parameter
Value
Soil classification
Silty sand
Clay content
low; 5-10%
Moisture content
mostly saturated (see below)
Hydraulic conductivity:
^horizontal
^vertical
7x10"5 to 2x10"3 cm/sec or 0.2-6.6
ft/day;
^verticalls approx. 10-100 times less
than Khorizontal. or 0.003 to 0.3 ft/day
Inorganic compounds:
Potassium, soluble
Nitrate/nitrite
Phosphate as P
2-10 mg/L
0.2-1.0 mg/L
0.1-0.5 mg/L
pH
5.5 to 7.2; mean 7.0
Total organic carbon
4-500 mg/L; mean 50 mg/L
Dissolved oxygen
0.1-0.8 mg/L; mean 0.1 mg/L
Eh
-175 to 30 mV; mean -50 mV
Maximum treatment depth:
Saturated thickness treated:
approximately 30 ft
25-27 ft
6
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
-------
4. TECHNOLOGY DESCRIPTION
This field demonstration evaluated in situ anaerobic bioremediation as a technology to treat chlorinated
VOCs in soil and groundwater. Bacteria metabolize soluble organic and inorganic compounds to provide
energy for the growth and maintenance of bacterial cells. The complex organic molecules that bacteria
consume are converted to new cells and various simpler compounds, such as carbon dioxide, that are
released back into the environment. This process is referred to as biodegradation. Biodegradation has
been used very cost effectively for more than a century in public and industrial wastewater treatment
systems. Since bacteria occur naturally in both soil and ground water environments, bioremediation
technologies attempt to stimulate the activity of these naturally occurring (or introduced bacteria) to
degrade contaminants in a cost-effective manner. Bioremediation is being considered more often as the
processes that control the biological degradation of contaminants in soil and ground water become better
understood.
In Situ Anaerobic Bioremediation Technology Description
In order to produce new bacterial cells, bacteria require carbon, nitrogen, phosphorus, and energy sources,
as well as a number of trace minerals. Electrons are released by the biochemical reactions that metabolize
complex organic compounds for energy. Biological systems capture this biochemical energy through a
series of electron transfer (redox) reactions. The bacteria that are most commonly used in bioremediation
systems use organic compounds as their source of carbon and energy; these carbon compounds are
referred to as electron donors. Bacterial respiration requires that some chemical compound is available to
act as a terminal electron acceptor. Common electron acceptors used by bacteria include oxygen, nitrate,
sulfate, Fe3+, and carbon dioxide.
Recently, a class of anaerobic bacteria has been identified that uses halogenated organic compounds as
their electron acceptors. The chlorinated VOCs present in the soil and ground water at the Northeast site
are among the halogenated organic compounds that can be used in this manner. Halogenated compounds
have a high oxidation state; and when a halogen (e.g. chlorine) is chemically replaced by hydrogen, the
oxidation state of the chemical is reduced. This process is referred to as reductive dehalogenation, and it
forms the basis of the anaerobic process used by the in situ bacteria at the Northeast site. Under
anaerobic conditions, chlorinated compounds can be degraded via reductive dehalogenation reactions to
successively lower chlorinated degradation products, and finally to compounds of significantly lower
toxicity. This process is illustrated for TCE below.
TCE DCE VC ethylene, ethane
step 1 step 2 step 3
Biological activity is frequently limited by the availability of a single growth factor (e.g. electron acceptor,
electron donor, nitrogen, etc.) and supplying the proper growth factor can often stimulate bacterial growth
and biodegradation rates. For in situ bioremediation applications, nutrients or electron acceptors are often
injected into the contaminated area to enhance the existing microbial degradation processes. Effectively
delivering nutrients requires that factors such as site permeability and geochemistry be considered. Each
class of contaminant varies in its susceptibility to biodegradation and factors such as aquifer oxidation-
reduction potential, microbial ecology, and contaminant toxicity will affect the success of bioremediation at
a site. The effective application of in situ bioremediation therefore depends upon careful consideration of
the geologic and hydrologic properties at the site and on the type and concentration of contaminants to be
treated. Bench scale treatability studies with aquifer soil and ground water samples are highly
recommended prior to full-scale implementation of most bioremediation projects.
The application of in situ anaerobic bioremediation for the degradation of chlorinated solvents has received
significant interest due to the excellent results obtained in laboratory and small pilot-scale applications
using these processes. These studies have shown that the injection of simple nutrients can significantly
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
7
-------
accelerate the natural degradation of compounds such as PCE, TCE, DCE, carbon tetrachloride, and
methylene chloride in soil and ground water. Some companies hold patents on certain aspects of
accelerated in situ anaerobic bioremediation for the treatment of chlorinated solvents. Sites interested in
the use of this technology should be aware that patent related issues may need to be addressed.
Evaluations of the monitoring data from the Northeast Site suggested that microbial dechlorination is
occurring naturally. DCE and vinyl chloride (VC) are degradation products of TCE that were measured in
high concentrations but were not contaminants originally disposed of at the site, which suggests that a
population of dechlorinating microorganisms is relatively active at Pinellas. Based on these evaluations
and the review of the site hydrologic conditions, it was expected that nutrient injection would be effective in
accelerating the anaerobic microbial degradation of the major COCs at the Northeast Site.
Hi Technology Advantages
The treatment of VOC-contaminated soils and ground water using nutrient injection to stimulate and
accelerate in situ anaerobic bioremediation offers the following advantages:
~ contaminants are treated in situ with little waste generation,
~ contaminant degradation can be relatively fast,
~ bioremediation is capable of reducing contaminants to very low levels,
~ the process stimulates a microbial population that can continue to feed off the dissolved phase of a
continuing source after nutrient injection ceases, and
~ often provides a low overall remediation cost relative to other technologies.
Technology Limitations
The treatment of VOC-contaminated soils and ground water using nutrient injection to stimulate and
accelerate in situ anaerobic bioremediation offers the following limitations:
~ contaminant degradation enhancement is dependent on adequate nutrient delivery to all areas of
contamination before the nutrients are directly metabolized, which often is primarily a function of site
hydrogeology and the appropriate mixing of nutrients, contaminants, and active microbes,
~ site conditions (e.g., soil and ground water chemistry, reductive processes, etc.) must be conducive to
the stimulation of biological activity to be effective,
~ bioremediation will not directly degrade contaminants occurring in an immiscible phase,
~ high concentrations of contaminants often are toxic to microoganisms,
~ bioremediation may be difficult to optimize at sites with multiple contaminants of concern,
~ incomplete biodegradation of contaminants can lead to the generation of degradation products that are
just as toxic or even more so than the parent contaminants, and
~ regulatory concerns over chemical injections into aquifers.
8
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
-------
H Treatability Study
Through the ITRD Program, laboratory batch and column biotreatment studies were performed under
anaerobic conditions using aquifer sediments and ground water from the Northeast Site. These studies
were used to assess methods for stimulating and/or optimizing the existing anaerobic biological activity at
the Northeast Site.6The laboratory studies generated information on contaminant degradation rates, the
reductive dechlorination process, and byproduct formation for several different nutrient combinations and
concentrations. The nutrient mixtures used included combinations of trace nutrients such as potassium
and phosphorus, and other nutrients such as sodium benzoate, sodium lactate, methanol, and casamino
acids. Nutrient concentrations generally ranged from 100-400 ppm.
The study showed that two nutrient combinations, both of which included methanol, were effective in
reducing both TCE and methylene chloride and that degradation rates of as high as 1-2 ppm/per day were
achievable for TCE. The results also showed that with these nutrient mixtures dehalogenaton of TCE did
not stop at any intermediate degradation products. In the case of toluene and trace contaminants, it was
not determined from this laboratory study what conditions would optimize their utilization or degradation.
Under the existing site conditions, toluene can degrade through fermentation, while simple electron
acceptors are available to accelerate toluene treatment.
Based on the laboratory data, a preliminary full-scale bioremediation system cost and performance
estimate was developed. From these engineering estimates, in situ anaerobic bioremediation appeared to
be a very cost effective and rapid technique for treating ground water of low to moderate contaminant
concentration (less than 200 ppm) at the Northeast Site. It was expected that areas of significantly higher
contaminant concentration would probably need to be treated by a more aggressive treatment method.
m Pinellas In-Situ Bioremediation Pilot System Description
Based on the laboratory treatability study results, and the engineering cost and performance estimates of
in situ anaerobic bioremediation, a large pilot-scale remediation system was designed and constructed at
the Northeast Site. The system was operated for approximately five months to assess the field
performance of this technology and to identify the optimum operating parameters for a full-scale system.
Historical data was used to select an area within the Pinellas Northeast Site that was understood to contain
the entire suite of chlorinated compounds found at the site and with contaminant levels ranging from at
least 100-200 ppm. If the initial concentrations were too high, there was a potential that the microbial
population would be inactive. If the initial concentrations were too low, contaminant degradation could be
difficult to monitor. Thus, an area expected to have mid-range contamination levels, as shown in Figure 3,
was chosen for the in situ bioremediation pilot-study.
The hydraulic modeling, design, construction, and operation of the bioremediation pilot system and the
associated monitoring well network are discussed in detail in this section. The operational concept
developed for the pilot system was to create a closed-loop ground water recirculation system where
ground water could be continually circulated through the treatment area while nutrients were added to the
circulated water to accelerate in situ contaminant degradation. This was expected to minimize external
ground water influence on performance assessment results, minimize nutrient loss and accelerate
biodegradation, and eliminate the need for ground water treatment or disposal. A large number of
clustered monitoring wells were also installed in the treatment area in order to assess contaminant
degradation and system performance throughout all levels of the treatment area.
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
9
-------
Figure 4 shows the general layout of
the treatment area and perimeter
and clustered monitoring wells. Four
fully screened monitoring wells were
installed in the perimeter of the study
area to perform flowmeter testing of
the aquifer matrix. The flowmeter
testing determined the relative
hydraulic conductivities of the zones
indicated in the cross section in
Figure 5. The central treatment area
is approximately 45 ft x 45 ft.
The overall design, configuration,
and location of the extraction and
injection wells were developed
based on a number of system
performance assessments using
MODFLOW, a two-dimensional
ground water flow model. The
modeling looked at nutrient delivery
and movement through the
treatment area based on several
possible vertical and horizontal
system configurations and well
locations as well as the site
hydrogeologic data. This modeling
effort suggested that ground water
circulation using horizontal wells and
trenches would provide better Figure 4. Map of the Pinellas bioremediation area,
nutrient delivery across the horizontal layers of
relatively low vertical hydraulic conductivity where contaminant concentrations were highest.
To achieve a vertical hydraulic gradient, a horizontal extraction well with a 30 foot screened section was
installed through the center of the treatment area in a zone of higher conductivity 16 ft below ground
surface (bgs). The ground water extracted from the horizontal well was then returned to the aquifer via
one of the four infiltration points shown in Figure 5. The first three points were gravel-filled, surface
trenches (A, B, & C) which were 30 ft long, 8 ft deep, and at least 2 ft wide. The fourth infiltration point (D)
was a horizontal well similar to the extraction well but installed at 26 ft bgs. MODFLOW simulations
indicated that this well and trench system would create a general flow pattern through the treatment area
as shown in Figure 6, under nominal operating conditions. The system was designed to allow reversal of
the extraction and infiltration points, providing flexibility in optimizing nutrient delivery to the different aquifer
levels across the treatment area if needed.
The ground water monitoring system shown in Figure 4 included 16 clusters of 4 sampling points to create
a three-dimensional monitoring network of the treatment area. These monitoring points were installed at
discrete depths starting at a depth corresponding to the elevation of the bottom of the trenches. The "A"
depth was 8-10 ft bgs, the "B" depth was 12-14 ft bgs, the "C" depth was 18-20 ft bgs, and the "D" depth
was 22-24 ft bgs. The "B" and "D" depths were chosen to correspond with the layers of lower hydraulic
conductivity within the study area, which contained the maximum contaminant concentrations. This was
an effort to monitor bioremediation system performance under worst case conditions.
PZ-11A. PZ-11E
pz-nc^
N
PJ-11D
?Z-13AJ&PZ-,3S
RZ-13C®PZ-13D
WELL TW-3
WELL TW-2
PZ If
PZ-12AS^,PZ
PZ-12C pz^J^cS
dc«bpz-i(
TRACE OF
HORIZONTAL
WELLS
8®
WELL
LINE
WELL
¦SECTION
10'
PZ-14A00PZ 148
©0
PZ-14C PZ-14D
10
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
-------
o
0
CD
Q.
&
1
0)
=3
3D
CD
"O
O
Si
T)
s'
CD
CO
C
i*
=3
0)
ct>
CD
O'
CD
3
CD
a
0)'
Grovel-Tilled
Nutrient Infiltration
Trenches
Sornple
Point
Cluster
Futty
Screened
- Well
F ully
Screened
W-lt
Lithology ond
Hydroulic
Conductivity
10*
lend Surface
Zone 1: Sond, fine
groined. sheKy,
*ith orgonics
5
Avg. Kh :* t,5 ft/doy
Kv =* 0.2 ft/doy
Zone 2: Sond, fine~to--
very fine groined. sUly.
slightly clayey
Avg. Kh £r 0.2 ft/doy
Kv a ,002 ft/doy
¦tl
--15'
Zone 3: Sond. fine
grained, slightly-to-
very slightly silty
Avg. Kh ts 6.6 ft/day
~ ~ 20' Kv a 0.7 ft/doy
Shotlow Horizontal Evtroction Well
Zone 4: Sand, fine
groined, slightly silty
~Q_
Avg. Kh 2* 0.76 ft/doy
Kv =* .008 ft/doy
2one S: Sond. fine
grained. phosphqltc
?q» Ava. Kh a? 10+ H/dov
Howthorn Group
Deep Horizontal Infiltration Well "0*
30'
Confining Unit
Feet
BIS
JT -+ IS
Figure 5. Cross Section of Treatment Area Looking West.
-------
0 5 to 15 20 25 30 35
Meters
Tick marks are 10 days on tracks
Figure 6. MODFLOW model of system ground water flow patterns and transit times.
Treatment System Schematic and Operation
Figure 7 is a process schematic of the operation of the pilot anaerobic biotreatment system. In this
system, the extracted ground water was pumped from the horizontal extraction well, monitored
continuously for contaminant concentrations with an automated field GC, had nutrients added in-line, and
was then returned to the aquifer through the infiltration trenches and the horizontal infiltration well. The
trenches had float switches installed just below ground surface that operated solenoid valves allowing
ground water and nutrients to enter at a steady rate without overflow. When all three surface trenches
were filled to their recharge capacity, a fourth solenoid valve would open to allow the nutrient rich ground
water to enter the aquifer from the lower horizontal infiltration well in the treatment area.
Each infiltration point was separately metered for flow, and each infiltration point had a separate stock tank
of nutrient solution so that the amount introduced into each point could be calibrated against the
corresponding ground water flow. Total ground water flow through each infiltration point, and the nutrient
solution used from each stock tank was recorded daily. The use of individual stock tanks also provided the
capability to conduct a multi-tracer study. The tracers were introduced into the nutrient solution tanks in a
controlled, continuous release so that nutrient transport could be easily monitored. Because both upward
and downward ground water movements were being studied, two different tracers were used. Bromide
was selected for tracking the upward flow from the horizontal infiltration well and iodide was used for
tracking the downward flow from the surface trenches.
An enclosed equipment control pad was located approximately 50 feet east of the system. All nutrient
drums, nutrient pumps, flow meters, solenoid valves, and a filter were located at the control pad.
12
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
-------
Anaerobic In-Situ Bioremediation System
Process Schematic
Control Pad (Shed)
nnn
Nutrient Drums
^ _2T ^
Nutrient Pumps
Infiltration Trenches
Horizontal Extraction Well
RW
Submersible
Pump
EXPLANATION
Horizontal Infiltration Well
Flow Meter
Solenoid Valve
Figure 7. Bioremediation pilot system process diagram.
¦¦ Key Design Criteria
The in situ anaerobic bioremediation pilot system was designed for two main objectives:
~ develop a nutrient delivery system capable of providing a mixture of nutrients to the subsurface within
the heterogeneous aquifer, such that the nutrients will be delivered to all levels in the treatment area
within an approximately 6-month operating period, and
~ create a closed-loop ground water recirculation system that minimizes external influences and losses
and requires no ground water disposal.
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
13
-------
Operating Parameters
Operating parameters were adjusted slightly during the pilot test to help optimize operating conditions for
the bioremediation system. The major operating parameters needed to assess the performance and cost
of the bioremediation system were considered to be pumping rates, nutrient concentrations, tracer
concentrations, and well redevelopment frequency. The general operating parameters for the system are
summarized in Table 3.
Table 3. Operating parameters affecting treatment cost or performance.
Parameter
Value or Specification
Optimal pumping rate from horizontal extraction well
1.5 gpm
Optimal pumping rate to infiltration trenches A, B, and C
0.2 gpm each
Optimal pumping rate to horizontal infiltration well (D)
0.9 gpm
Concentration of methanol added to the ground water
60 ppm
Concentration of sodium benzoate added to the ground water
120 ppm
Concentration of sodium lactate added to the ground water
180 ppm
Concentration of iodide to Trenches A, B, and C
250 ppm
Concentration of bromide to horizontal infiltration Well (D)
250 ppm
Frequency of redevelopment of horizontal extraction well
average of once every 3 weeks
Frequency of redevelopment of horizontal infiltration well
once
The horizontal extraction well was located at a depth of 16 feet bgs in a zone of relatively high hydraulic
conductivity. A pumping rate of 1.5 gpm was sustained through this well. The horizontal infiltration well
was at a depth of 26 feet bgs in a zone of somewhat lower hydraulic conductivity, however, it could accept
a pumping rate of 0.9 gpm of the recirculated ground water under a pressure gradient of 5-10 psi above
the ambient hydraulic head. The infiltration trenches were 8 feet deep and located in a zone of lower
hydraulic conductivity. Each trench accepted only approximately 0.2 gpm of recirculated ground water.
Nutrient concentrations added to the ground water were based on the results of the original ITRD
treatment study and follow-on discussions by the ITRD committee.6 Methanol, sodium benzoate, and
sodium lactate, at concentrations of 60, 120, and 180 ppm, respectively, were added. This mixture of
electron donors was used to provide nutrients that would be used at different rates by the bacteria in the
aquifer to degrade the major COCs so that the reducing power could be delivered to all treatment levels.
Methanol and benzoate additions were initiated on February 12, 1997 and discontinued on June 30, 1997.
Lactate was added from February 27, 1997 to June 23, 1997. The tracer concentrations added were used
to insure that the breakthrough of nutrient rich ground water could be detected at the monitoring point
locations. Iodide, at a concentration of 250 ppm, was added to trenches A, B, and C. Bromide, at a
concentration of 250 ppm, was added to the horizontal infiltration well (D). All tracer additions were
initiated on March 7, 1997. Tracer additions to trenches A, B, C, and well D were discontinued on June 4,
May 13, May 28, and April 25, respectively.
Due to subsurface conditions at the Northeast Site and possible fouling of well screens, redevelopment of
the horizontal wells by hydraulic surging was used to ensure efficient operation of the system. The
horizontal extraction well was redeveloped on February 24, March 6, March 13, March 31, April 8, April 22,
June 4, and June 16. The horizontal infiltration well was redeveloped once on June 3, 1997.
14
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
-------
5. IN SITU ANAEROBIC BIOREMEDIATION SYSTEM PERFORMANCE
The bioremediation pilot operations at the Northeast Site were conducted to assess the applicability of
nutrient injection to accelerate the degradation of the chlorinated contaminants of concern and to identify
optimal operating parameters. These data were used to determine the expected costs and performance of
a full-scale system at the site.
Hi Demonstration Objectives and Approach
The objectives of the pilot in situ anaerobic bioremediation project were as follows:
1. Convert chlorinated VOCs in the ground water at the Northeast Site to innocuous biodegradation
products using in situ anaerobic biodegradation,
2. Determine the suitability and effectiveness of this technology on site soil and ground water, and
estimate the time period needed to meet cleanup objectives,
3. Evaluate the horizontal extraction well and infiltration gallery design configuration for full-scale
implementation and determine hydraulic parameters, such as flow rates, residence times, flowpaths,
and treatment levels,
4. Determine optimal operating parameters and conditions for treatment and potential scale-up, such as
nutrient concentrations, nutrient half-lives, and contaminant degradation rates,
5. Collect sufficient cost data to support cost estimates for a full-scale system; and
6. Conduct the pilot test in a location that is representative of site-wide conditions, is not impacted by
neighboring treatment operations (rotary steam stripping), and does not detrimentally impact ongoing
ground water recovery systems.
IH Performance Evaluation Criteria
The performance criteria considered in evaluating this in situ anaerobic bioremediation system included:
~ nutrient transport and utilization in the remediation study area,
~ contaminant degradation rates and the reduction in mass of the contaminants
~ fate of chlorinated solvent degradation compounds, and
~ levels to which contaminants can be reduced.
The evaluation data were collected by a monitoring program that included: semimonthly sampling for
VOCs, methane, ethane, and ethylene; weekly tracer sampling; semimonthly sampling of nutrients
following tracer breakthrough; weekly measurements of water levels until ground water flow conditions
stabilized; and maintenance of a daily log to record operational data.
Performance Summary
Table 4 summarizes the pretreatment (February 1997) and post-treatment (July 1997) contaminant
concentrations at each of the 64 monitoring points within the bioremediation treatment area, as well as the
period of time required for the nutrients to reach each monitoring point. The conceptual model of this
microbially mediated, in situ, reductive dechlorination system requires that nutrients (primarily electron
donors), contaminants, and adapted microorganisms reside or mix at the appropriate ratios and
concentrations for significant contaminant reduction to occur.
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
15
-------
to n
ikthr
wet
7
9
16
1
8
7
9
1
11
16
11
2
7
7
16
4
7
7
2
7
9
9
1
3
4
7
1
3
16
5
1
cline
%
-104
97
-154
85
89
44
2817
99
99
-174
71
98
99
61
44
-6
97
-56
1063
99
55
-273
-324
99
-255
-4
79
99
Table 4. Pre arid post-treatment monitoring well contaminant
(Concentration units are micrograms per liter)
concentrations.
Toluene
Methylene Chloride
TCE
cis-1,2-DCE
Vinyl Chloride
before
after
decline
before
after
decline
before
after
decline
before
after decline
before
after
decline
%
%
%
%
%
47
58
-23
ND
<5
ND
<1
.
ND
<1
.
ND
<1
.
ND
13
-
ND
<5
-
ND
<1
-
220
<1
99
880
16
98
ND
<1
-
ND
<5
-
ND
<1
-
ND
<1
-
22
54
-145
310
310
0
ND
<25
-
ND
<5
-
630
<5
99
640
<5
99
1,600
130
92
ND
<10
-
ND
<2
-
ND
<2
-
83
<2
98
100
700
-600
ND
<50
-
ND
<10
-
ND
<10
-
16
<10
38
210
<10
96
ND
<50
-
ND
110
-
ND
450
-
12
990
-8150
2,200
400
82
1,400
<50
96
420
<10
98
4,200
<10
99
3,500
<10
99
190
1,100
-479
ND
<100
-
ND
<50
-
31
<50
-
240
<50
80
1,900
12,000
-
ND
<250
-
ND
370
-
1,900
21,000
-1005
11,000
14,000
-27
9,800
7,50Q...
23
1,500
<100
93
280
<100
64
6,600
1,500
77
11,000
4,100
63
1,900
J-50(L
^ 21
3,800
<50
98
560
<50
91
1,900
<50
97
2,700
150
94
3,600
3,500
3
ND
<100
-
ND
<100
-
260
<250
-
490
<250
50
190,000
74,000
61
25,000
<2,500
90
210,000
20,000
90
96,000
110,000
-15
37,000
12,000
68
4,800
20,000
-316
ND
<250
-
ND
<250
-
4,200
2,500
41
12,000
6,500
-46
7,800
16,000
-105
ND
<50
-
ND
<50
-
ND
4,700
-
ND
3,700
-
470
62
87
ND
<25
-
ND
<5
-
ND
<5.0
-
ND
<5
-
1,400
3,000
-
ND
<100
-
1,400
730
-
860
1,700
-
1,500
260
-
130
590
-354
ND
<150
-
ND
<50
-
9
67
-644
58
57
2
1,500
1,700
-13
3,300
56
98
560
<25
96
1,600
140
91
1,800
68
96
17
15
12
ND
<5
-
ND
<1
-
ND
<1
-
ND
14
-
440
2,500
-468
ND
<100
-
440
320
27
25
430
-1620
52
55
_6
530
1,400
-164
680
<500
26
230
<200
13
800
16,000
-1900
840
14,000
-1567
2,800
980
65
ND
47
-
ND
<25
-
4,600
48
99
3,400
31
99
2,000
160
92
49
<10
80
ND
<2
-
14
4
71
67
50
25
250
2,100
-740
ND
<100
-
600
200
67
ND
1,200
-
150
1,400
-833
100
1,300
-1200
ND
<50
-
ND
<20
-
31
250
-706
94
280
-198
1,600
1,600
0
ND
<50
-
ND
<25
-
3,600
59
98
4,600
43
99
2,300
4,000
-74
810
<50
94
ND
1,900
-
350
3,400
-871
700
1,300
-86
71,000
100,000
41
190,000
190,000
0
160,000
240,000
-50
210,000
170,000
19
38,000
20,000
47
150
840
-460
140
<100
29
ND
<20
-
120
59
51
320
63
80
2,400
940
61
2,900
31
99
370
<20
95
3,800
68
98
4,500
43
99
-------
o
o
CD
Q.
5
6
QJ
=3
o
CD
¦§
O
5
CD
CO
Er
Q)
3
Cr
o'
CD
O'
cB
3
CD
g.
CD*
o'
3
Time to nutrient
Well
breakthrough
Toluene
Methylene Chloride
in weeks
before
after
decline
before
after
decline
before
%
%
9A
12
46
980
-2030
ND
<100
ND
9B
9
ND
<1,100
-
160,000
140,000
13
31,000
9C
16
ND
97
-
ND
<5
-
ND
9D
5
ND
<500
-
ND
<2,500
-
ND
10A
7
9,900
2,400
76
ND
130
-
ND
10B
7
2,200,000
110,000
95
760,000
240,000
68
1,700,000
10C
11
1,000
1,200
-20
ND
<250
-
ND
10D
3
19,000
850
96
2,400
<100
96
1,200
11A
-
8
350
-
ND
<5
-
ND
11B
-
71
4,200
-
86
1,600
-
380
11C
16
ND
320
-
ND
<50
-
ND
11D
16
30
530
-1667
ND
<100
-
ND
12A
5
230
930
-304
ND
<120
-
ND
12B
-
56
250
-
22
470
-
170
12C
-
ND
92
-
ND
<100
-
ND
12D
4
72
760
-956
7
<50
-
ND
13A
.
7,500
140
.
ND
<25
.
ND
13B
16
68,000
47,000
-31
ND
<2,500
-
ND
13C
-
ND
<50
-
ND
<5
-
ND
13D
3
47
1,200
-2453
ND
<100
-
ND
14A
8
ND
<1,000
-
ND
<1,000
-
82,000
14B
16
ND
5,800
-
ND
<10,000
-
380,000
14C
-
ND
19
-
ND
<50
-
ND
14D
3
ND
1,600
-
ND
<250
-
97,000
15A
5
26
120
-362
ND
<25
-
440
15B
9
690
1,800
-161
ND
<250
-
2,000
15C
16
ND
76
-
ND
<25
-
ND
15D
2
1,300
1,100
15
1,100
<100
91
1,600
16A
9
120,000
47,000
61
ND
<2,500
-
6,000
16B
14
39,000
7,900
80
ND
<500
-
ND
16C
15
140,000
48,000
66
28,000
<2,500
91
310,000
16D
3
1,000
1,700
-70
ND
<250
-
ND
TCE
after
-J
cis-1,2-DCE
Vinyl Chloride
Total Chlorinated VOCs
sline
before
after decline
before
after
decline
before
after
decline
%
%
%
%
.
ND
<20
.
990
25
97
990
49
95
92
80,000
21,000
74
18,000
21,000
-17
289,000
182,000
37
-
ND
1,200
-
ND
1,200
-
0
2,496
-
-
56,000
21,000
63
9,000
34,000
-278
65,000
55,000
15
-
ND
77
-
ND
190
-
0
342
-
96
170,000
64,000
62
130,000
25,000
81
2,950,000
403,000
86
-
21,000
520
96
7,000
54
99
28,057
997
96
98
21,000
100
99
21,000
160
99
45,600
260
99
-
5
<10
-
21
<10
-
34
18
-
-
170
680
-
400
560
-
1,036
3,026
-
-
ND
160
-
ND
240
-
0
416
-
-
390
960
-146
900
1,400
-33
1,290
2,382
-84
-
ND
<25
-
19
<25
-
32
0
99
-
79
220
-
310
170
-
602
917
-
-
ND
260
-
ND
1,100
-
0
1,360
-
-
78
190
-144
180
290
-61
277
492
-78
-
ND
<5
-
ND
<5
.
0
60
_
-
33,000
8,100
75
36,000
24,000
22
69,000
32,100
54
-
ND
2,800
-
ND
770
-
0
7,570
-
-
31
190
-513
100
300
-200
142
490
-245
93
65,000
56,000
14
19,000
45,000
-137
166,000
107,000
36
21
490,000
390,000
20
95,000
56,000
41
965,000
746,000
23
-
ND
280
-
ND
150
-
0
640
-
99
18,000
7,800
57
ND
7,200
-
115,000
15,530
86
84
110
230
-109
55
160
-191
605
473
22
-600
570
12,000
-2005
170
1,600
-841
2,740
27,600
-907
-
ND
270
-
ND
280
-
0
660
-
97
2,500
410
84
4,500
440
90
9,700
893
91
83
110,000
13,000
88
27,000
35,000
-30
143,000
48,000
66
-
51,000
3,300
94
50,000
4,100
92
101,000
13,400
87
92
240,000
88,000
63
48,000
9,500
80
626,000
121,500
81
-
21,000
210
99
7,000
1,400
80
28,000
1,610
94
-------
Due to the nature of the subsurface hydrogeology, transport and mixing times for the added nutrients will
vary across the site, and depending on system design and operation, nutrient delivery to some portions of
the aquifer could require significant amounts of time. Therefore, good system performance often requires
nutrients that will not be consumed immediately at an injection location and can be transported quickly and
efficiently through the subsurface to all levels of the treatment area.
System Hydraulics and Nutrient Transport
At the pumping rate of 1.5 gpm, approximately 250,000 gallons of water, or about two pore volumes, were
circulated through the pilot study treatment area over a five-month period. Tracers were used to identify
nutrient breakthrough at each monitoring point for the first ten to twelve weeks of system operation. When
over 50% of the monitoring points showed breakthrough, tracer additions were stopped and nutrient
concentrations were monitored directly. Tracer and nutrient breakthrough were defined as a concentration
greater than 10% of the injected concentrations. Tracer breakthrough was observed earliest (1-2 weeks)
in several of the "D"-level wells in the central part of the treatment area. The "B" and "C" level wells
showed much slower tracer and nutrient breakthrough and the perimeter wells (Wells 9,10,11, and 14)
showed limited breakthrough during operations. Of the 48 central monitoring points, 43 wells (90%),
experienced breakthrough during the first 16 weeks of operation. Of the wells showing breakthrough in the
central treatment area, 77% did so in the first two to three months of system operation. Overall, Levels A,
B, C, and D had breakthrough in 88%, 81%, 81%, and 100%, respectively, of their monitoring points during
the first 16 weeks of operation. These results suggest that though some of the recirculated water may have
escaped from the treatment area in levels A and D, water was effectively circulated within the central
treatment area of the pilot system.
The tracer and nutrient breakthrough observations were consistent with model predictions. Based on
initial modeling with a flow rate of 2 gpm, it was expected that nutrient delivery to the ""B" level could take
three to four months. It was hoped that this flow rate could be achieved from the extraction well, though a
flow of only 1.5 gpm was sustained. A higher flow rate might have improved nutrient delivery to the "B"
level monitoring points. From field observations, it appears that the extraction well efficiency was reduced
in part due to borehole skin effects caused by the drilling fluid used during installation. Biobore™ by Baroid
was used by the drilling contractor and appears not to have degraded as well as expected. Additionally,
the infiltration trenches accepted a smaller volume of water than was initially expected, which in turn limited
nutrient delivery into the "A" and "B" level monitoring points.
Since enhanced bioremediation depends on adequate nutrient delivery, bioremediation at this site will be
controlled by the rate at which nutrients can be delivered into the middle and identified lower permeability
zones. This is one reason why the two horizontal well system was implemented, since it allows for
reversing the injection and extraction wells and providing more flexibility in delivering nutrients to all levels
in the aquifer. However, in order to minimize complications in evaluating the operational performance of
the pilot system, reversing the operation of the two horizontal wells was not exercised during the pilot
operations. Based on the results of this pilot study, it appears that a properly designed and operated
system can deliver nutrients to all of the aquifer at this site within six to eight months.
Nutrient Fate Assessment
For this pilot study, a mixture of electron donors was selected based on the consideration that the relative
degradation rates for the different compounds would allow for the delivery of the reducing power of the
nutrients to be spread throughout the treatment system. Lactate was used because it is a readily available
carbon source that should be quickly oxidized to acetate, which is expected to degrade much slower.
Benzoate was expected to degrade slower than lactate but would yield partial oxidation products such as
acetate that again should take longer to degrade. Methanol was expected to degrade slower than lactate,
but faster that benzoate, while also acting as an electron donor to accelerate biodegradation of methylene
chloride.
18
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
-------
During system operations, sodium benzoate was detected in 59 monitoring points. Of these, 5 had
reported concentrations higher than the initial feed concentrations and were not included in the
calculations. Using the remaining 54 data points, the average half-life of the nutrients in the aquifer were
calculated by the EPA's Kerr Laboratory to be about 110 days, with the calculated half-lives ranging from
12 to 949 days. The 110-day nutrient half-life should be considered a minimum in that dilution, dispersion,
and retardation effects were not accounted for due to the difficulty in assessing their relative contributions
to the observed concentration decreases.
Similar calculations for lactate proved even more difficult due to the inability to resolve lactate/acetate
contributions in the analytic methods used. It should be noted, however, that the observed concentrations
at several locations in the pilot study area yielded lactate/acetate concentrations near or even above the
initial lactate injection concentration of 180 mg/L. This suggests that lactate/acetate half lives in this system
of a year or more are possible or that benzoate was being metabolized to acetate. The methanol
concentrations varied widely across the treatment area. At some points, methanol concentrations in
excess of ten times the added concentration were reported. This suggests that components in the ground
water may have interfered with the laboratory analysis.
Together, these results suggest that the nutrients necessary to enhance bioremediation at this site were
successfully delivered to the areas reached by the injected water. The detection of significant
concentrations of benzoate, methanol, and lactate/acetate throughout the treatment area at the end of pilot
system operation suggests that the bioavailable reducing power from the injected nutrients was not a
limiting factor for this pilot effort and should not be a limiting factor in the operation of a properly designed
full-scale system. Based on the system operation, nutrient delivery can be expected to occur in all areas
of the aquifer including the middle and lower permeability areas within the effective half-lives (four months
to a year) determined for these nutrients.
Contaminant Degradation and Reduction Rates
Contaminant levels encountered at the different monitoring points within the treatment area generally
ranged from 10 to 400 ppm total chlorinated VOCs, with one monitoring point location in Level "B" having a
concentration as high as 2900 ppm. The bioremediation system at this site was designed to develop a
recirculation cell within the aquifer creating complex, three-dimensional, ground water and contaminant
mixing, making the evaluation of system performance more complicated. Because of the mixing and
recirculation of the ground water, temporal variations in contaminant levels in individual monitoring points
could be expected. Therefore, it was important to look at contaminant reductions across the whole site, at
various treatment levels, at individual wells, and in the extraction well to help assess system performance
and define actual contaminant reductions due to biological treatment.
As shown in Table 4, in wells with nutrient breakthrough, chlorinated VOC concentrations were commonly
observed to fall by 60%-99% from their pretreatment levels in as little as four to eight weeks after nutrient
arrival. In wells with at least six weeks of nutrient availability, TCE was reduced by 94%, DCE by 54%,
vinyl chloride by 58%, methylene chloride by 60%, and toluene by 80%. In wells where nutrient
breakthrough was not evident or of short duration, there was a reduction of only10-15% in total chlorinated
VOCs and toluene. These results suggest that though contaminant reduction in part is probably the result
of ground water mixing and contaminant redistribution, contaminant reduction is significantly greater in
wells where nutrients are available. Likewise, because of the ground water recirculation, increases in
contaminant levels in some wells should be expected. Contaminant increases were observed primarily in
wells with lower (~1 ppm) concentrations. Many of the increases observed were for DCE or VCE, which is
consistent with the reductive dechlorination process. Significantly fewer concentration increases were
observed for TCE and methylene chloride in the wells with long term nutrient availability.
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
19
-------
WELL 2D
0.14
350
0.12
VC
300
-- DCE
TCE
o
E
E
.E
250
- - Ethene
- - Meth. CI.
Toluene
0.08
200
Tracer
0.06
-- 150
0.04
100
0.02
-- 50
4
8
18
0
2
6
10
12
14
16
20
Weeks After Start of Nutrient Addition
WELL 4B
vc
DCE
TCE
Ethene
Meth. CI
Toluene
T racer
6 8 10 12 14
Weeks After Start of Nutrient Addition
20
Figure 8. Contaminant monitoring data for well points 2D and 4B.
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
-------
Figure 8 shows two wells, Well 2D and Well 4B, that are located in the central treatment area and provide
a range of the observed monitoring well data. Well 2D is a low concentration well with very little TCE that
is near the horizontal recirculation well. Nutrient arrival occurred shortly after nutrient addition as shown by
the tracer concentration data measured. Well 4B has a much higher concentration of TCE and is in the
lower permeability zone where nutrient breakthrough took much longer, approximately two months, and the
level of nutrients delivered to this area was probably lower, as evidenced by the much lower tracer
concentrations. The results for Well 2D are representative of many of the "D" level wells, showing a
reduction of the chlorinated contaminants to regulatory levels in several weeks. Both DCE and vinyl
chloride were reduced at a rate of 0.10-0.20 ppm per day. Since toluene was not specifically targeted for
biological degradation, toluene was monitored to assess contaminant reductions attributable to mixing and
redistribution. Over this period, toluene levels changed slightly while ethylene increased substantially,
suggesting that anaerobic reductive dechlorination was the major mechanism for contaminant reduction.
The results for Well 4B are typical of many "B" level wells, showing a much longer period for nutrient
delivery and contaminant reduction than Well 2D. This is in part due to the much higher contaminant
concentrations. The reductions in contaminant levels, including toluene, is similar until late in the
operations where TCE continues to decrease and DCE begins to increase. The initial TCE reduction rate
observed after nutrient arrival is over 2 ppm per day and as the TCE concentration approaches 0.2 mmol/L
(25 ppm), the degradation rate slows to 0.10-0.20 ppm per day observed in Well 2D.
In evaluating the monitoring data from all wells showing early to mid-period nutrient arrival, contaminant
reduction rates of 1-2 ppm per day were observed for the high (above 200 ppm) contaminant levels to
approximately 0.05-0.20 ppm per day for wells with contaminant levels of less than 20 ppm. These rates
suggest that areas with moderate TCE contamination would require one to two months after nutrient arrival
to reduce TCE to levels of 5-10 ppm and another one to two months to reduce the TCE to regulatory
levels. The further reduction of the DCE and vinyl chloride produced to ethylene could take similar periods
of time. This suggests that as much as a year may be necessary for areas of high contaminant
concentration to be reduced to regulatory levels for all contaminants following nutrient availability.
Figures 9 and 10 show contaminant reduction trends by level for toluene, TCE, DCE, and vinyl chloride
and the production of ethylene for the wells in the central treatment area that received nutrients. Since the
monitoring points in each level do not receive nutrients at the same time, a classic step-wise dechlorination
sequence was not expected. Each level was analyzed separately in an effort to identify trends in
contaminant distribution and biological degradation. Similar to the results of Figure 8, contaminant
reduction at each level begins as the wells receive nutrients. Level D, where most of the wells have
nutrient arrival very early during system operation, is the only level where measurable ethylene production
occurred. Level A, where nutrient arrival was longer, reductions in DCE and corresponding increases in
vinyl chloride are observed. In Levels B and C, which have much higher contaminant concentrations and
much shorter periods of nutrient availability, show much slower overall contaminant reductions. The
contaminant reduction results in Levels B and C are overshadowed by the data from several monitoring
points with high contaminant concentrations that had nutrient breakthrough in only the last four to five
weeks of system operation. Contaminant reduction in the wells in these two levels with longer nutrient
availability show more pronounced contaminant reductions as shown in Table 4.
Contaminant Reduction Levels
Though the pilot system was not designed nor operated to meet any specific cleanup criteria during the
short operational period, final contaminant levels for many monitoring points were measured below 50-100
ppb, while several of the lower concentration wells had contaminant concentrations reduced to below 5
ppb. The data also show that monitoring points with individual contaminant concentrations above 5-10
ppm were not reduced to allowable levels during the pilot operations. This data, along with the
degradation rate results discussed above, suggests that though contaminant degradation is rapid once
nutrients are available, the operational period of a bioremediation system could be controlled by
degradation rates at the lower contaminant levels.
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
21
-------
LEVEL A
¦ Ethene
Toluene
6 8 10 12 14
Weeks After Start of Nutrient Addition
LEVEL B
Ethene
Toluene
A
We s
6 8 10 12 14
Weeks After Start of Nutrient Addition
22
Figure 9. Contaminant monitoring data for Level A and B Wells.
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
-------
LEVEL C
Ethene
Toluene
Wells
6 8 10 12 14 16
Weeks After Start of Nutrient Addition
LEVEL D
6 8 10 12 14
Weeks After Start of Nutrient Addition
Figure 10. Contaminant monitoring data for Level C and D Wells.
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
-------
Extraction Well Monitoring Data
In addition to the 64 monitoring points, the extracted ground water was monitored every two hours using an
in-line, automated, gas chromatograph (GC). The system was continuously calibrated using a prepared
standard. The data were compared with GC data from grab samples collected from the well. Both sets of
data were shown to be within the accuracy limits of the two instruments. The average daily data, shown in
Figure 11, provide additional evidence of the biodegradation occurring in the subsurface and the overall
rates of contaminant reduction. In general, the extracted ground water trends and the data from the
monitoring points in the interior of the treatment zone correlate well. Contaminant reduction in the ground
water began to occur rapidly in mid-April, which is the time when approximately half of the monitoring wells
that would experience nutrient arrival had done so. Contaminant reduction continued throughout system
operations, but was much slower as additional wells experienced nutrient arrival. The sharp increases in
the contaminant concentrations and the data gaps shown for the GC generally correspond to
redevelopment of the extraction well, which occurred as discussed previously on February 24, March 13,
March 31, April 8, April 22, June 4, and June 16. The automated monitoring system worked well during the
pilot operations and appears to be a simple method that can be used to guide operations and define
sampling events for a full-scale bioremediation system.
10
9
VC
Note: Data gaps are periods when
the GC was not operational
8
MC
cis12DCE
7
6
TCE
TOL
5
4
3
2
03
2
Q_
<
Q_
<
cL
<
>N
<0
2
>H
CO
2
>¦.
to
:s
DATE
Figure 11. Continuous monitoring data of the extracted ground water.
Reduction of Other Contaminants
Table 4 and Figures 8-11 support the observation that across the site, enhanced bioremediation occurred
as a result of system operations. As discussed, the pilot operations were designed to optimize conditions
for the reduction of the chlorinated contaminants and were not optimized to reduce toluene. Though
toluene concentrations decreased over much of the site, residual toluene levels will have to be addressed
in a full-scale system design. This may require the addition of a different nutrient mix at some point during
operations, though oxygen injection is often used to quickly, and effectively reduce toluene concentrations
to regulatory levels.
24
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
-------
A summary of the performance of the in situ anaerobic bioremediation pilot system is provided in Table 5,
relative to stated performance measures and project objectives. Overall, the system met most of the
identified system performance objectives.
Table 5. Bioremediation system performance summary.
Performance Measures
Values/ Results
Treatment volume:
Ground water treated:
Extraction/reinjection rate:
Approximately 45 ft x 45 ft x 30 ft, 60750 ft3
Approximately 250,000 gallons, about 2 pore volumes
Approximately 1.5 gpm
System nutrient transport effectiveness:
Level A- 8-10 feet deep
Level B - 12-14 feet deep
Level C - 18-20 feet deep
Level D - 22-24 feet deep
Nutrients were distributed to approximately 90% of the
central monitoring points in 23 weeks,
Nutrients delivered to 88% of the monitoring points
Nutrients delivered to 81% of the monitoring points
Nutrients delivered to 81% of the monitoring points
Nutrients delivered to 100% of the monitoring points
Nutrient effectiveness:
Nutrient viability:
Significant reductions in all contaminants occurred
within 4-8 weeks after nutrient arrival at a well point
Average nutrient half-life of 110 days, up to > 1year
Contaminant degradation rates:
>100 ppm concentration levels
1-10 ppm concentration levels
1-2 ppm per day
0.05-0.10 ppm per day
Reduction of contaminants of concern:
Toluene
TCE, DCE, vinyl chloride, methylene chloride
50-70% within 4-8 weeks of nutrient arrival
90-95% within 4-8 weeks of nutrient arrival
Chlorinated solvent degradation product production
General decline in all contaminants with some
temporary increases in degradation products, followed
by reduction of the degradation products themselves
by biological degradation
Waste Generated
None, all extracted ground water was recirculated
Achievable contaminant reduction levels:
Some contaminants were reduced to the 50-100 ppb
level, the detection limit for most analyses. Some
monitoring points with concentrations less than 10
ppm were reduced to <5 ppb.
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
25
-------
6. IN SITU ANAEROBIC BIOREMEDIATION SYSTEM COST
The Pinellas in situ anaerobic bioremediation project was constructed and operated by Lockheed Martin
Specialty Components (LMSC) under their cost-plus-fee management and operations (M&O) contract with
the DOE. Several organizations, including the EPA National Risk Management Laboratory, Sandia, FDEP,
and several industry participants, played an important role in the design, operation, and monitoring of the
remediation system. These services were often in an advisory or consulting role, though some direct
support was provided to the project. For example, FDEP provided three-dimensional graphical data of
sampling results on the Internet for use by the ITRD participants. Where appropriate, direct support costs
are included in Table 6, which shows project costs in accordance with the interagency work breakdown
structure adopted by the Federal Remediation Technologies Roundtable.
Table 6. Bioremediation Project cost by interagency work breakdown structure.
Cost element
(with interagency
WBS Level 2 code)
Description
Costs
($)
Subtotals
($)
Mobilization and preparatory
work(331 01)
Four, fully-screened vertical wells at corners of
treatment area
$ 10,000
$ 35,000
Flow model calibration and analysis
$ 15,000
Flow meter testing
$ 10,000
Monitoring .sampling, testing,
and analysis (331 02)
Monitoring point network
$ 15,663
$ 238,310
Pre- and post-treatment coring
$ 20,000
Laboratory - VOCs (biweekly)
$ 48,728
Laboratory - methane, ethane, ethylene
(biweekly)
$ 81,900
Laboratory - tracers (biweekly)
$ 9,492
Laboratory - nutrients (weekly)
$ 8,860
Field GC Labor
$ 10,000
Iodide tracer
$ 2,568
Bromide tracer
$ 869
Labor
$ 40,230
Ground water collection and
control (331 06)
Horizontal well installation
(2 wells-240 feet long w/30 feet screens)
$ 41,235
$ 87,536
Pumps and controls
$ 9,256
3 infiltration trenches
$ 7,925
Plumbing, utilities, pad, shed, etc.
$ 29,120
Biological Treatment (331 11)
Operations labor
$ 19,440
$ 23,748
Methanol ~60kg
$ 174
Sodium benzoate -120 kg
$ 376
Sodium lactate (2 drums) -170 kg
$ 3,483
Utilities: Electricity
$ 275
General requirements (331 22)
Project management and engineering
$ 12,480
$ 12,480
TOTAL
$ 397,074
26
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
-------
As discussed earlier, the goal of the operation of this in situ anaerobic bioremediation pilot system was to
assess the ability of nutrient injection to accelerate the reduction of contaminants at the Northeast Site and
to identify optimum conditions for the design and operation of a full-scale system. Since the pilot system
was not operated to meet any specific cleanup criteria and the treatment area selected had nominal
contaminant levels higher than much of the Northeast Site, it would be inappropriate and possibly
misleading to specify a direct treatment cost for a full-scale system implementation. However, general
observations and estimates of biological treatment capital and operating costs can be made.
As can be seen from Table 6, almost two-thirds of the overall cost of the pilot system operation were
related to the extensive monitoring conducted. This level of monitoring was used in an effort to better
understand the operation of the pilot system and to track the biodegradation occurring at different levels in
the aquifer. As extensive a monitoring system and the associated costs would not be required for a full-
scale system. The monitoring cost data does show how a system like the continuous monitoring field GC
can be used to provide significant bioremediation data at a low cost. Typical fully automated continuous
monitoring systems like the one used at Pinellas are available for less than $50K.
From an operational viewpoint, the pilot system pumped approximately 250,000 gallons of water, this
allowed for treatment of approximately two pore volumes of contaminated ground water in the central
treatment area. The direct biological treatment costs for water treatment during the pilot operations were
therefore approximately $0.10-0.12 per gallon of water treated. Since additional treatment would be
required to reduce contaminants to regulatory levels in some areas, these costs are only approximate.
Actual costs will vary based on the contaminant levels and the hydrogeology encountered across the site,
though much of the site has significantly lower contaminant levels than the pilot study area.
The system construction, operations labor, and chemical costs are often proportional to the scale of a
project and can be more easily used to quantify potential full-scale system operating and construction
costs. Initial estimates of the construction and operating costs of an insitu anaerobic bioremediation
system were developed by the ITRD Program based on site hydrogeologic data and the results of the
biodegradation treatment study7. The initial estimates were developed by two, environmental, consulting
firms familiar with implementing bioremediation systems. They estimated that a vertical well based
treatment system would take approximately a year to construct, require about a year to deliver nutrients to
all areas of the site, and about six months to a year for contaminant degradation, for a three to four year
total remediation period. The nutrient costs were estimated to be about $750K, with system operational
costs of $600K per year. Capital costs for a ground water extraction and recirculation system were
estimated at $2M, for an estimated total site remediation cost of $3.5-4.5M. These cost estimates
assumed application of a bioremediaton system in the areas of low to moderate concentration (less than
200 ppm), while the higher contaminant levels would be treated with another more aggressive technology.
The performance of the pilot system substantiated many of the initial full-scale system performance and
unit cost assumptions and the related overall system cost estimates. Based on the pilot data, it appears
that it would take about 6-8 months to get nutrients to all levels of the aquifer and another 8-12 months for
contaminant degradation and reduction in all levels to regulatory limits, or about two years for system
operations. Based on nutrient costs and the levels used for the pilot and a two year operational period,
nutrient costs for treatment of the three to four-acre Northeast Site would be about $750K to $1M,
depending on the savings of buying nutrients in bulk quantities. Scaling of the construction costs of the
horizontal pilot-system for application to the entire Northeast Site suggest a full-scale cost of approximately
$3-4M. These results suggest that a full-scale bioremediation system based on a horizontal extraction
and recirculation design would cost $4.5-5.5M to construct and operate for a two to three-year period.
The required operational period and associated costs for some portions of the system might be reduced
since much of the Northeast Site has nominal contaminant levels of 10-30 ppm, rather than the higher
contaminant levels observed in the selected pilot-system treatment area.
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
27
-------
7. REGULATORY/INSTITUTIONAL ISSUES
In July 1993, DOE, EPA, FDEP, and LMSC entered into an agreement with the ITRD Program to evaluate
innovative technologies to remediate ground water contamination at the Pinellas STAR Center Northeast
Site effectively and expeditiously.
Under Section II.D.1 of the Department of Energy HSWA Permit, interim measures may be conducted at
SWMUs after EPA approval. Section II.D.3 requires the permitee to notify the EPA Regional Administrator,
as soon as possible, of any planned changes, reductions, or additions to the interim measures. The
proposed in situ anaerobic bioremediation project would temporarily interrupt the operation of the existing
interim measures (pump and treat with air stripping). Therefore, the DOE provided notice to the EPA and
FDEP of a planned change (the implementation of ITRD field activities) to the approved interim measures
and proposed implementation schedule for concurrence in August 1996. Authorization for implementation
of the activities was also received in August 1996.
Initially, both industry and regulatory participants of the ITRD committee were concerned that underground
injection control (UIC) requirements may prevent the recirculation of ground water. Through assistance
from the FDEP, discussions were held with the State of Florida, who has UIC delegation, about this issue.
Because of the system design (i.e., in situ recirculation) the state determined that no UIC permit was
required.
8. SCHEDULE
Figure 12 shows the tasks and schedule associated with the in situ anaerobic bioremediation project at the
Pinellas STAR Center.
1997
ID
Task Name
Start
Finish
Jul | Auq | Sep
Oct I Nov I Dec I Jan I Feb I Mar Apr I May I Jun I Jul I Auq I Sep
Oct I Nov | Dec I Jan
1
-------
9. OBSERVATIONS AND LESSONS LEARNED
Cost Observations and Lessons Learned
Based on the construction and operating treatment cost data from the pilot system operation, it appears
that in situ anaerobic bioremediation can be a cost-effective method for reducing chlorinated VOCs in
subsurface environments, given favorable geochemical, microbial, and hydraulic/hydrologic characteristics,
such as at the Pinellas Northeast Site.
Performance Observations and Lessons Learned
Laboratory batch and column studies, using site soil and ground water, if used correctly can help identify
whether a population of anaerobic microorganisms exists capable of remediating the contaminants of
concern at a site and which nutrients can enhance degradation of those contaminants.
Good nutrient distribution is critical to effectively enhancing contaminant degradation in a treatment area.
Therefore, a thorough and detailed understanding of the site hydrology is necessary to design an effective
nutrient delivery system. Flow meter field testing and numerical modeling should be used to help identify
the best nutrient delivery system for a site.
The recirculation system of infiltration trenches and two horizontal wells developed for this site proved
effective in the pilot operations. Because of the recirculation design, no waste water was generated.
Improvements, such as deeper surface trenches and the flexibility of switching extraction and injection
roles of the horizontal wells, could accelerate nutrient delivery to the middle and lower permeability layers
and overall remediation of the site. Effective redevelopment of long horizontal wells can sometimes be
difficult and should be considered in the overall design and operation of a full-scale system.
At monitoring points where nutrient breakthrough was observed for at least four to eight weeks, significant
declines in total chlorinated VOC concentrations (70-95%) were generally observed. These values
correlate well with the results from the extraction well. For those wells where nutrient arrival was not
observed, generally in the areas of lower permeability or in perimeter wells, only modest contaminant
reductions were recorded. Though the nutrient mixture and concentrations were not specifically optimized
during pilot operations, degradation rates as high as 1-2 ppm per day were observed in higher
concentration areas (>100 ppm), while in areas with lower concentrations degradation rates ranging from
0.05 to 0.10 ppm per day were observed. It is possible that the nutrient mixture might be adjusted to
further accelerate contaminant reduction. There was little evidence of significant degradation product
buildup at monitoring wells after nutrient arrival.
Contaminant degradation observed in the pilot study at concentrations higher than 200 ppm suggests that
anaerobic bioremediation is more robust and has a broader operational capability than previously
identified.
Summary
The extensive modeling and hydrogeologic, nutrient transport, and operating cost data developed during
the pilot system operation suggest that nutrient addition to stimulate in situ anaerobic biological
degradation of chlorinated solvent contaminated soil and ground water is a feasible, cost- effective,
remediation approach at the Pinellas Northeast Site for areas of moderate contamination. The limiting
factors for successful, cost-effective implementation are the ability to deliver appropriate nutrients to all
contaminated areas and hydraulic travel times.
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
29
-------
10. REFERENCES
1. Installation Assessment, Pinellas Plant, U.S. Department of Energy, Comprehensive Environmental
Assessment and Response Program, Albuquerque Operations Office, Albuquerque, NM, 1987.
2. RCRA Facility Investigation Report, Pinellas Plant, U.S. Department of Energy, Environmental
Restoration Program, Albuquerque Operations Office, Albuquerque, NM, 1991.
3. RCRA Hazardous and Solid Waste Amendments Permit, U. S. Department of Energy Pinellas Plant,
Largo, Florida. EPA ID No. FL6-890-090-008, U.S. Environmental Protection Agency, February 9,
1990.
4. Interim Corrective Measures Study, Northeast Site, TPA2 6350.80.01, prepared by CH2M Hill for the
U.S. Department of Energy and General Electric Company, Neutron Devices Department, Largo, FL,
May 1991.
5. Corrective Measures Study Report, Northeast Site, Pinellas Plant, Largo, Florida, U.S. Department of
Energy, Environmental Restoration Program, Albuquerque Field Office, Albuquerque, NM, 1993.
6. Flanagan, W.P., et al. "Anaerobic Microbial Transformation of Trichloroethylene and Methylene
Chloride in Pinellas Soil and Ground Water," General Electric Corporate Research and Development
Center, Schenectady, NY, May 1995.
7. Pinellas Northeast Site Project, Innovative Technology Review, letter to David Ingle, Department of
Energy, from Mike Hightower, Sandia National Laboratories, February 8, 1995.
30
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
-------
11. VALIDATION
Signatories:
"This analysis accurately reflects the performance and costs of the remediation."
S.
David S. Ingle, ER Program Marpger
U.S. Department of Energy
Grand Junction Office
Mike Hightower, Technical Coordinator
Innovative Treatment Remediation Demonstration Program
Sandia National Laboratories
Guy Sewell, Research Microbiologist
National Risk Management Research Laboratory
U.S. Environmental Protection Agency
Cost and Performance Report - Pinellas In Situ Anaerobic Bioremediation
-------
Department of
Environmental Protection
Lawton Chiles
Governor
Twin Towers Building
2600 Blair Stone Road
Tallahassee, Florida 32399-2400
Virginia B. Wetherell
Secretary
April 14, 1998
Mr. David Ingle
c/o MACTEC-ERS
7887 Brian Dairy Road
Suite 200
Largo, Florida 33777
Dear Mr. Ingle:
I have reviewed the "Cost and Performance Report, In Situ Anaerobic Bioremediation, Pinellas
Plant Northeast Site" final draft dated March 16, 1998. I concur with the purpose of the report. Unless
the EPA or other parties desire modifications, we recommend that the report proceed to "final"
designation.
If I can be of any further assistance with this matter, please do not hesitate to contact me at
904/921-9983.
Sincerely,
JohnR. Armstrong P. G.
Remedial Project Manager
Ar./ /V /f?g
Date
CC: Cheryl Walker-Smith, USEPA Atlanta
Satish Kastury, FDEP
JJcMl/ ESN 5A/
"Protect, Conserve and Manage Florida's Environment and Natural Resources"
Printed on recycled paper.
c:\aimstron\pmeI76.doc
-------
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION 4
ATLANTA FEDERAL CENTER
61 FORSYTH STREET, SW
ATLANTA, GEORGIA 30303-8909
APR 2 8 1398
4WD-FFB
CERTIFIED MAIL
RETURN RECEIPT REQUESTED
The United States Department of Energy
Pinellas Plant
ATTN: Mr. David Ingle
P.O. Box 2900
Largo, FL 34649
SUBJ: Revised Cost and Performance Report: In Situ Anaerobic Bioremediation
Pinellas Northeast Site, Largo, Florida
Final Draft - March 16, 1998
DOE Pinellas Plant, FL
EPA I.D. Number FL6 890 090 008
Dear Mr. Ingle:
The Environmental Protection Agency (EPA), Region 4, has completed our review of the
revised Cost and Performance Report for the in situ anaerobic Bioremediation project conducted
at the Northeast Site (Solid Waste Management Unit PIN 15). This work was conducted under
the Innovative Treatment Remediation Demonstration (ITRD) agreement between EPA Region
4, the Florida Department of Environmental Protection (FDEP), the U.S. Department of Energy,
Clean Sites, Inc., the EPA Technology Innovation Office, and Sandia National Laboratories.
This team's mission was to identify and demonstrate various innovative technologies applicable
to this and other contaminated waste sites around the country. This is the third innovative
technology demonstration conducted at the Northeast Site.
This project utilized the experience and expertise of personnel from the EPA National
Risk Management Research Laboratory (NRMRL) and Lockheed-Martin in the design,
construction, implementation, and sampling efforts. The FDEP participants played a key role in
system design, permitting issues, and computer support. The facilitator of the ITRD effort, Mr.
Mike Hightower, deserves special credit for unifying and focusing the efforts of this team, and in
the overall success of this ITRD project.
Recycled/Recyclable • Printed with Vegetable Oil Based Inks on 100% Recycled Paper (40% Postconsumer)
-------
2
The EPA approves of the changes made in this revised document and looks forward to
the possibility of other ITRD projects occurring across Region 4.
Any and all concerns raised by the FDEP for this revised document must be addressed
as required under their authority.
Sincerely,
Carl R. Froede Jr., P.G.
DOE Remedial Section
Federal Facilities Branch
Waste Management Division
cc: J. Crane, FDEP
E. Nuzie, FDEP
J. Armstrong, FDEP
------- |