NCD980840409_19950425_Charles Macon Lagoon & Drum_FRBCERCLA SPD_Ground Water Bioremediation Pilot Study-OCR

•:~.,-·_·
State of North Carolina
Department of Environment,
Health and Natural Resources
Division of Solid Waste Management
James B, Hunt, Jr., Governor
Jonathan B. Howes, Secretary
William L. Meyer, Director
April 21, 1995
Memorandum
TO: Arthur Mouberry, Chief
Groundwater Section
Division of Environmental Management (DEM)
FROM:
RE:
David J. Lown ~
Environmental Engineer
Superfund Section
Prefinal Remedial Design -Upper Macon Source Area
Groundwater Treatment System
Charlie Macon Lagoon and Drum Storage (Macon Dockery) NPL Site
Cordova, Richmond County
EPA is completing a Remedial Design Report for this National Priorities List site. The
NC Superfund Section is reviewing the draft reports and will be submitting comments to EPA by
May 10, 1995.
The documents being reviewed are attached. The remediation plan calls for pumping and
treating the groundwater plume for VOCs and discharging the treated water to infiltration
galleries, The substantive requirements for a non-point source discharge permit will have to be
met; however, because the discharge is on-site, a permit is not required. Source areas will be
treated with soil vapor extraction technology,
Please forward this document to the appropriate sections of DEM and submit any
comments to the NC Superfund Section, We would like to have the views and permitting
requirements of Air Quality, Groundwater, and Water Quality Sections of DEM. If you or your
staff have questions, please call me at (919) 733-280 I.
Attachment
cc: Jack Butler
P.O. Box 27687, Raleigh, North Carolina 27611-7687 Telephone [phone] FAX 919-71&-3605
An Equal Opportunity Affirmative Action Employer 5m':, recycled/ l 0% post-consumer paper
• Macon/Dockery Site
Richmond County, North Carolina
February 6, 1995
Ms. Giezelle Bennett
Remedial Project Manager
U.S. EPA, Region IV
345 Courtland Street
Atlanta, GA 30365
RECEl'fE.O
FEB 141995
5UPERFUND SECTION
•
Reply to: Technical Committee
c/o David L. Jones
Clark Equipment Company
P. 0. Box 7008
South Bend, IN 46634
Phone: [phone]
Fax: [phone]
RE: Macon/Dockery Site -Cordova, North Carolina
Groundwater Bioremediation Pilot Study
Dear Ms. Bennett:
The Macon/Dockery Site Group's Technical Committee recently h~ld a .meeting with their
contractors and technical consultants: ·Representatives from eacli of the participating PRPs,
de maximis, inc., RMT, Inc., and DuPont Environmental Remediation Services (DERS)
attended the meeting. The primary focus of this meeting was to discuss progress to date on
the Groundwater Bioremediation Pilot Study. As you are aware, the study was initiated on
December 19, 1994 with the introduction of substrate amendments into the six nutrient
addition wells.
Issues discussed at the meeting included several topics of concern shared by EPA during the
recent teleconference on January 6, 1995. The following conclusions were formed at this
meeting:
1. The right timeframes and schedule restrictions under which the demonstration program
must be conducted indicates that there simply wi 11 not be sufficient data and too many
unknowns for the completion of a 90% design submittal for this innovative technology
by April 17, 1995. As you are aware, this is the agreed upon date for which the
Group's consultants were to provide you with a 90% design for either the
bioremediation technology or the groundwater extraction and treatment technology.
2. Additional site information has allowed DERS, our subcontractor for this pr_oje~t, to
revise the present worth estimates for this· project. The new estimates dearly show that
yeast extract is not a cost-effective choice as a substrate and that a new substrate, as yet
unidentified, would need to be found.
• •
Ms. Giezelle Bennett Page 2 February 6, 1995
Based on the above conclusions, the Group's Technical Committee has made a decision to
terminate the bioremediation field demonstration program and will authorize RMT to begin
preparation of the design elements for the groundwater extraction and treatment components
for all Site source areas. Nutrient amendments and site sampling have been terminated as of
February 3, 1995. DERS will prepare a final summary report which will present all
demonstration program data and the laboratory microcosm study data for the soil samples
collected at other site source areas. This report will be submitted following receipt of all
laboratory data. In the meantime, RMT will continue to assist the Group with bidding the SVE
system and the perimeter groundwater extraction and treatment systems and will also begin
preparation of the 90% design of the source area groundwater extraction and treatment
system. This 90% design will be submitted to. U.S. EPA on April 17, 1995 in accordance with
the approved schedule.
In closing, the Group and their contractors and consultants would like to emphasize that this
decision to switch the technology selection for the Macon/Dockery Site source areas is based,
at this time, on the factors of schedule and cost-effectiveness. It is not founded in the
interpretation of technical and scientific data generated from the site studies. In fact, the data
that is available from the studies to date are very positive with regard to the viability of
bioremediation technologies at this Site. The Group intends to continue to explore the
feasibility of intrinsic bioremediation as it may apply to the site source areas.
It is also requested that the option to reopen an investigation into bioremediation technologies
be retained for the Macon/Dockery Site source areas. The important factors that the Group
will consider for potentially requesting U.S. EPA to reopen and reconsider the bioremediation
technology include: developments in the use of alternate and more cost-effective substrate
materials; development and demonstration of alternative amendment distribution systems; and
indications of significant limitations on the ability of the groundwater extraction and treatment
system to meet performance standards.
If there are any questions concerning the contents of this letter, please contact me at
[phone] or \,Vayne Barto of de maximis, inc. at [phone].
Very truly yours,
p~~
David L. Jones
Project Coordinator
Macon/Dockery Group Technical Committee Chairman
/b
cc: Macon/Dockery Site Group Members
Wayne F. Barto, de maximis, inc.
Paul Furtick -RMT, Inc.
Kevin White, DERS
•
~
DuPont Chemicals
• DuPont Chemicals
1007 Market Street
Wilmington, DE 19898
[:s~'-: ~:C~'; '.October 20.
OCT 2 ~ ;99~-\
1994
Mr. David J. Lown SUPE:sriJMD S:':G?'.Oflf / ·
North Carolina Dept. of Environment-;-Health--;-and-Natural Resources
Division of Solid Waste Management
Superfund Section
P.O. Box 27687
Raleigh, NC 27611-7687
RE: Information regarding the use of in situ microbial
reductive dehalogenation at the Macon-Dockery Site
Dear Dave:
Enclosed please find two pieces of Information which relate to the
current status of microbial reductive dehalogenation in remediating
chlorinated aliphatic hydrocarbons. The first document describes the
definitive effort made by DuPont at our Victoria, TX site which provided the
basis for our current U.S. patent on this process. The second document is
an EPA flier describing a current EPA/industry collaboration to develop
promising innovative technologies in which microbial reductive
dehalogenation is a key technology to be evaluated in this program.
We believe that significant opportunity exists at the Macon-Dockery
site for a successful demonstration of this technology, which has been shown
at other sites to remediate TCE to levels which are below current laboratory
analytical detection limits. DuPont and the Macon-Dockery Technical
Committee look forward to further discussions with NCDEHNR and EPA-
Region IV on this important issue.
cc: Ms. Giezelle Bennett
Mr. David Jones
Mr. Wayne Barto
E. I, du Pont do Nemours and Company
Since el~
Clifford Lee
Senior Consulting Engineer
DuPont Corporate Remediation Group
@Printod 011 Rccyclod Papor
CH-7651 Rev. 5/93
' I • •
A FIELD EVALUATION OF IN SITU MICROBIAL REDUCI1VE DEHALOGENATION
BY THE BIOTRANSFORMATION OF CHLORINATED ETHENES
R. E. Beeinan, I. E. Howell, S. H. Shoemaker, E A Salazar, and J. R. Buttram
ABSTRACT
Results have demonstrated the 'in-situ" biotra.asformation of tetrachloroethene (PCE),
trichloroethene (TCE), 1,2-dichloroethene (DCE), ch!oroethane (CA), and vinyl chloride (VC) to
ethane and cthcne ming microbial reductive dehalogenation. These investigations were conducted
in a 12.2 X 36.6 m test zone in ao aquifer which has PCE contamination at the Du Pont Plant
near Victoria, Texas. Initial concentrations in the aquifer of PCE, TCE, and DCE approximated
10, 4, 4 µM (1700, 535, 385 ppb), respectively. After 2 year.; of anaerobic treatment, chlorinated
hydrocarbons were below detectable !eve.ls (BDLs) in some monitoring wells using United States
Environmental Protection Agency (EPA) Method 8240 (PCE, TCE, DCE <5 ppb; 0.03, 0.04,
0.05 µ..\{, respectively; VC, CA < 10 ppb, <0.16 /ol-1'\i}-Microbial reductive dechlorination was
accomplished by alternately pumping either a benzoate or sulfate solution into the circulating
groundwater. MaM balance estimates using bromide in the test zone apprmrimated 55 percent,
while recovery o[ influent PCE and daughter products as ethene in the last monitoring well also
approximated 55 percent AJ a control, two additional wells near the test site were circulated in a
similar manner. but did not receive benzoatc or sulfate addition.. No lo.ss of the PCE was
observed in the control site. We conclude that in some aquifers, reductive dehalogenation can be
used to remove halogenated hydrocarbons from groundwater.
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INTRODUCTION
Toe p=nce and problems of halogenated organic compounds in aquifers have been well
documented. Conventional pump and treat technologies may contain or control halogenated
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organic plume movement. However, pump and treat technologies have limited applications for
aquifer and groundwater restoration. Innovative technologies which have the potential to
remediate aquifers, such as biological reductive dehalogenation, have been widely sought.
This paper summarizes a two-year investigation of 'in situ" microbial reductive
debalogenation of PCE to cthene in an aquifer underlying the E. L du Pont de Nemours and
Company (Du Pont) plant near Victoria, Texas. The study was completed in two phases. First, it
was demonstrated that PCE could be dechlorinated "in situ." ~nd, in a controlled field
experiment, PCE and its daughter products were degraded to ethene and ethane 'in situ,' under
sulfate-reducing conditions using benzoate as the electron donor. Initial concentrations of PCE,
TCE, and DCE in the pilot site approximated 10, 4 and 4 µM, respectively, while VC was not
detected. After two years, aquifer concentrations of PCE, TCE, DCE, VC, CA, and
dichloroethane (DCA; <5 ppb; 0.04 µM) were BDI..s.
MATERIALS AND METHODS
Study Area
The te45t aquifer underlies the former West Landfill on the Du Pont Pinnt near Victoria
Texas. Landfill construction depth apprCll<imated 5 m (15 ft; Figure 1) below the surface. The
landfill received a variety of solid and liquid wastes from industrial activities for about 20 years,
beginning in the early 1950s. It is underlain by a semi-confined sand aquifer (Zone B) the top of
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which is located about 18.3 m (60 ft) below tbe surface. Toe overlying strata stratigraphy consists
of interbedded san~ and clays of late Pleistocene age, leading down to the Zone B sand, which is
a relatively continuou& water-bearing sand averaging 12.2 to 18.3 m ( 40 to 60 ft) !hick.
The Zone B sand is composed of quartz. p!agioclase, potassium feldspars, carbonate rock
fragmentx, and rare mica grains. Analysis of 22 samples from the Zone B sand indicate an
average TOC of appraxim.ately 0.1 percent with a range between 0.07 to 0.71 percent. Hydraulic
conductivity of the sand was determined to be approximately 30 m/day from pump test data. The
natural groundwater movement is southwesterly at approximately 0.3 m/day with discharge toward
a man-made canal (Figure 1, Barge Canal) along the southwestern site boundary. PCE and
benzene waste placed in the landfill have migrated through the overlying strata and into the
Zone B aquifer. Currently, a state-of-the-art, pump and treat facility is used to control and
contain this groundwater contamination. This facility meets or exceeds all regulatory concerns of
the Texas Water CommiMion and EPA
Pilot Site Description. In Phase I, a 12.2 m X 18.3 m (40 X 60 ft) test site was
established in the '.Zone B sand consisting of recovery, monitoring, and recharge wells (Figures 1
and 2). All wells were screened in the top 4.6 m (15 ft) of the aquifer. The wells do not fully
penetrate the Zone B sand.
Wells 4N, 4, and 4S were extraction wells, while 1N, 1, and IS were re<:harge wells
(Figure 2). Wells 2 and 3 were monitoring wells. Pumping rates from Wells 4N, 4, and 4S were
11.4, 26.6, and 11.4 Umin (3, 7, 3 gpm), respectively. Wells lN, 1, and 1S delivered water back to
the Zone B sand at 11.4, 26.6, and 11.4 Umin, respectively. ~ water was brought to the surface
from the recovery wells, it passed through a sealed mixing manifold where nutrient additions were
made. Delivery from the nutrient feed tank was at 3.8 L/hr. A final concentration of either
0.3 mM (38 ppm) sodium benzoate or 0.4 mM (56 ppm) magnesium sulfate was pumped down
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the recharge wells. The recovery and recharge system was designed 10 prevent volatile losses due
to air stripping of the volatile organic compounds (VOCs).
For Phase II, a cew section of aquifer was included in the experiment (Figure 2). 1lris
was adjacent to Wells 4N, 4, and 4S. These wells were established at the same depth with the
same screened intervals as in Phase L The site dimen.1ions were enlarged to 12.2 X 36.6 iii ( 40 X
120 ft), and the recovery and recharge rateg remained the same as previously described.
Wells 7N, 7, and 75 were used as extraction wells, while Wells 2, 3, 4N, 4, 4S, 5, and 6 were wed
as monitoring wells. As before, Wells 1N, 1, and 1S were used to delivered water back to the
aquifer. For background gas anal)'Sis, Well 15 (not shown), which is located in the VOC plume,
but outside the hydraulic influence of the pilot site, was sampled.
Separately, Welli 99 and 174 were established near this second site as a control (Figure 2).
They were used to test the effects of simple circulation on the VOGi. This site was circulated at
approximately 19 Umin (5 gpm) without nutrient or feed stock additions.
Modeling of the circulation pattern between 99 and 174 and the flow of the pilot site
revealed significant interaction on both recovery and recharge patterns ( data not shown).
Therefore, after approximately 4 months of operations. flow between 99 and 174 was discontinued
and Well 99 was used as a monitoring well.
ANALYI'ICAL
Samples from wells were collected following proper EPA protocol. Briefly, monitor wells
were purged for three well volumes and then sampled using dedicated purge and gas bladder
pumps. Analy$is for halogenated compounds was accomplished using gas chromatography and
mass spcctromeuy by EPA Method 8240. Analysis for gases was by gas chromatography with
flame ionization detection following EPA Method 8015.
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RESULTS
Phase I: Demonstration ot PCE and TCE degradation "In-Situ"
Aerobic Treabnent. Figures 3, 4, and 5 display the variation in PCE, TCE, and DCE groundwater
concentration during 1990 in Wells 2, 3, 4N, 4, and 4S (Figure 2). This period encompassed the
time before and after the start of anaerobic treatment Anaerobic treatment began with the
addition of benzoate to the pilot site, on day 203.
Efforts to degrade PCE in the pilot site using aerobic techniques were unsuccessful
through day 203 (Figure 3). However, the aerobic remediation efforts reduced the groundwater
concentration of benzene in the pilot site to BDLs ( <5 ppb; data not shown).
GroUI1dwater PCE, TCE, and DCE median concentrations approximated 10, 4, and 4 µM,
respectively (Figures 3, 4, and 5), while the site was aerobic. No VC was detected while the site
was aerobic (Figure 6; <.16 ,..M; <10 ppb). Under aerobic conditions, the PCE, TCE, and DCE
concentrations were ~table, indicating no significant aerobic biodegradation during this period.
Anaerobic Treatment. Groundwater PCE and TCE concentration showed decreases after
1 month of anaerobic treatment beginning on day 203 (Figures 3 and 4). PCE concentrations in
all wells continued to decrease with time during Phase L PCE concentrations in Wells 2 and 3
decreased to BDL ( <0.1 µM; < 15 ppb), a reduction of at least 98 percent from previous aerobic
concentrations.
The TCE concentrations also decreased with time during Phase I (Figure 4 ). However,
unlike PCE, TCE remained detectable in groundwater from Wells 2 and 3 throughout Phase I.
Overall, through 4 months of anaerobic treatment, the groundwater TCE concentrations in
Wells 2 and 3 decreased approximately 85 and 89 percent, respectively.
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Toe groundwater DCE concentrations increased in all the wells until day 280 when it
began to decrease (Figure S). DCE in Wells 2 and 3 reached maximums near 23 and 26 µM
(2200 and 2500 ppb), respectively, an increase of approximately 7-8 fold. Groundwater DCE
concentrations decreased in all wells after day 280 to a final concentration ranging between
2-3 fold that of the original DCE concentration, before anaerobic trc,atment started.
Vinyl chloride concentrations remained undetectable or less than 1 µ.M in the site until
day 280 (Figure 6). Larger concentrations approximating 5 µ.M (310 ppb) were I.hen observed in
Wells 2 and 3. The increase in VC formation coincided with the decreas" in DCE concentration
(Figura 5).
We concluded that the groundwater concentrations of PCE and TCE in the pilot site were
converted to DCE and VC by microbial reductive dehalogenation. Also, we conclude that PCE
could be biodegraded to BOI....
Phase Il: PCE Daughter Product Blodegradation
The well field schematic for Phase II is shown in Figure 2. To test rhe effects of
circulation on the volatile chlorinated concentrations, Well 99 was circulated to Well 174.
Figure 7 displa)'3 the concentrations of PCE in Wells 2, 3, 7N, 7, 7S and Well 99. Circ.tlation of
Well 99 to 174 continued from day Oto 110, approximately 4 months. During this period,
groundwater PCE concentration increased at Well 99 from 15 to 24 µM (2475 ro 3960 ppb). This
compares to ground water PCE concentration of nondetectable for Wells 2 and 3 ( <0.1 ,..,\.i;
< 15 ppb) in the pilot site. This demonstrates that simple circulation of water did not cause the
disappearance of the PCE from the site. Similar results were obtained for TCE (data not shown).
Phase II site ciic:ulation began 011 day O for Graphs 7, 8, and 9 and lasted for 250 days.
During Phase II, sulf.ate anion concentration Wll$ kept above l mM in the pilot site. As before,
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the groundwater PCE and TCE were transformed rapidly into DCE and VC in the pilot site
(Figure& 7, 8, and 9; TCE data not shown). "The PCE and TCE concentrations were typically less
than 0.03 and 0.04 µ.M, respectively, in Wells 2, 3, 5, and 6 ( <5 ppb; Figure 7, TCE data not
sh=}-In contrast, groundwater DCE concentration increased to a maximum approximating
12 µ.M (1150 ppb) by day 110 in Wells 3, 5, and 6 (Figure 8). Therea~r. DCE declined until
day 187 in all the wells, nearing 1 ~ (96 ppb), where it remained through day 250.
The VC concentrations started at 3.5 ~ (186-310 ppb) and increased to a maximum
between 5-9 µM (190-560 ppb) fer Wells 2, 3, 5, and 6 (Figure 9). The VC concentration started
to decline on day 110 and continued to decline throughout the remainder of the year.
The DCE and VC could be biotransformed to ethenc gas, but previous research indicated
that biotransformation rates from VC to ethene gas were slow under anaerobic conditions (Major
and Hodgins, 1987). Also, a comparison of reed and daughter product formation in the site
needed to be performed.
The daughter production from the biodegradation of PCE has been identified as TCE,
DCE, VC, DCA, CA, and both ethenc and ethane (Sims et al. 1991). Therefore, we began an
investigation for these products in the groundwater at our pilot site on days 314 and 426 (Tablt:S
1 and 2, respectively).
Concentration of components in the feed stream were determined by analyzing Wells 7N,
7, and 7S for the •pecific halogenated compounds. These concentrations were multiplied by the
fractional contn1mtion for each well to define the total feed stream concentration. The results
were then summed for Wells 7N, 7 and 7S as the feed stream concentration. Flow from the feed
tank into this stream was ignored.
Table 1 displays the specific componenL'I in groundwater from each well, plus the
calculated feed stream on day 314. The feed stream contained 1.42 µ.M of PCE (235 ppb; Table
1). However, as the flow moved downgradient past Well 2, the groundwater PCE concentration
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was reduced by more than 90 percent to 0.06 µM. (10 ppb ). Groundwater from Wells 3, S, and 6
revealed no detectable PCB concentration ( <0.03 µM; <5 ppb).
Toe feed stream TCE concentration was 0.72 ,,M (95 ppb; Table 1). Groundwater
sampled from Wells 2 and 3 revealed concentrations of 0.09 and 0.19 µM., respectively. However,
TCE concentratiom were BDI.s in groundwater from Wells 5 and 6 ( <0.03 ,,M; <5 ppb ). ··
The feed stream DCE concentration was 0.85 µM (83 ppb; Table 1 ). This decreased in
the groundwater samples taken from downgradient wells to 0.25 µM in Well 6, a 71 percent
decrease acroM the pilot site.
The feed •tream VC concentration was 0.48 µM (30 ppb; Table 1). The VC
concentration increaoed in the groundwater taken from Well 2 to 1.07 µM. (67 ppb) and then
decreased to 0.58 (36 ppb) in groundwater taken downgradient in Well 6. The increase in VC is
comisteot with the biotransformation of PCB to VC. \Jsing the VC concentration in the
groundwater from Well 2, the decrease across the pilot site to Well 6 was 46 percent.
The f.eed stream CA concentration was 0.24 µ.M (15 ppb; Table 1). This concentration
increased in the groundwater acr~ the site to 0.50 µ.M (32 ppb) in Well 6. This is an increase of
two fold acros., the pilot site.
For ethene, the feed stream concentration was 0.87 µ.M (25 ppb; Table 1). No
groundwater samples were taken from Wells 2 and 3 for gas analysis. The ethene concentration
increased to 1.75 µ.M (52 ppb) in groundwater in Well 6. Ethane was not detected in the feed
stream or groundwater from the monitoring wells ( <0.16 µM; < 10 ppb ). Ethene was not
detected in Well 15, which is outside tbe pilot site. Therefore, the ethene present in the site was
due to the biodegradation of PCE and its daughter products to elhene.
The data shown in Table 1 indicates that PCE entering the pilot site in the feed stream
was being biotransformed into VC in the groundwater by WeU 2. 1bis was further biotransfonned
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into ethenc in groundwater by Well 6. It was concluded that some of PCE entering the site
appeared to be biotran.sformed into ethene.
Other daughter products were being formed and degraded "in situ." With the exception of
CA, th= daughter products should also form ethene. To estimate the mass balance in the pilot
site, individual halogenated concentrations in the feed stream were summed and compared ·to the
products found in groundwater from Well 6. Concentrations BDI.,; were ignored in these
summations. The summation of the components in the feed stream equaled 4.58 µ.M (Table 1}.
Summation of the components in Well 6 produced 3.08 µM. Comparison of the products in the
groundwater from Well 6 to the reactants in the feed •tream approximated 65 percent recovery.
To interpret the product recovety in the pilot site, a comparison was made to a
conservative tracer. This would account for dilution and dispersion with water outside the site. A
bromide anion tracer demonstrated that 55 percent of the bromide placed into the lN-1S wells
was recovered in the 7N-7S well!. Comparison between the recovery of the end products from
PCE degradation, 6S %, to the recovery of the bromide tracer, 55 %, indicated that the major
end product! from PCE biodegra.dation in the aquifer were reconciled.
Table 2 displays the specific components in groundwater from each well, plus the
calculated feed stream on day 426. PCE was present in the feed stream at 0.86 µM (143 ppb ).
The PCE concentration was BDI.., in all of the remaining monitoring wells.
TCE was also present in the feed stream at 0.79 µM (105 ppb; Table 2). It was BDI..s in
Wells 2, 4N, 4, 4S, 5, and 6. The only detectable concentration of TCE was in groundwater taken
from Well 3, just above the detection limit, at 0.06 µM (8 ppb ).
For DCE, the concentration present in the feed stream was 0.66 µ.M (64 ppb; Table 2).
Groundwater DCE concentiations were detected from Wells 2 and 3 at 0.06 and 0.19 µM (6 and
18 ppb), respectively. The groundwater concentration of DCE in Wells 4N, 4, 4S, 5, and 6 were
BDI..s.
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VC WM not present in the feed streams although it was detected on day 314 (Tables 1 and
2). Nor was it present in groundwater from the remaining monitoring wells ( <0.16 µM; 10 ppm.
Table 2} on the day 426 sampling. CA also was not detected in the pilot site on day 426, with the
exception of Well 6 where the concentration o[ chloroethane was 0.16 µM (10 ppb).
Ethene was detected in the feed stream at 0. 75 µM (Table 2). ln groundwater taken from
Wells 4N, 4, 4S, and 6, the concentration of elhene had increased to 1.46, 1.43, 2.11, and 1.71 µM
( 47, 46, 68, and 54 ppm), respectively. Ethene was BDl.s in groundwater ta.ken from Wells 15
and 99 ( <0.16 µ.M. <10 ppb). Since wells outside the pilot site (15 and 99} had no detectable
ethcne or ethane, then ethene or ethane in the pilot site must have come from the
biodegradation of halogenated hydtocarbom, notably PCE biodegradation. Ethane was only
present in groundwater taken from Wells 4N ar,.d 4 at 0.29 µM (10 ppm}. Since ethane was not a
detectable background gas, then the ethane in the pilot site came from the biodegradation of
chloroethane. DCA or 1,1 DCE were not detected in the pilot groundwater.
Recovery of feed stream reactants as products in groundwater from Well 6 reveal
appromnately 60 percent recovery on day 426 sampling. The ethene found in Well 6
approximated 55 percent of the chlorinated hydrocarbons in the feed stream. Again, both
compare favorably to the 55 percent recovery for the bromide tracer. Groundwater taken from
Wells 4N. 4, 4S, and 5 were free of demonstrable chlorinated hydrocarbons at the detection limits
of EPA Method 8240. Also, groundwate~ taken from Wells 2, 3, and 6 reveal low concentrations
of PCE daughter products ranging between 0.06 and 0.19 µM for DCE, TCE, or CA
In summary, PCE and its daughter products, TCE, DCE, VC, CA have been anaerobically
biodegraded to BDL6 in wells 4N, 4S, and 5. Ethene and ethane, the dechlorinated products
from microbial PCE degradation, are detected at near stoichiometric concentrations based upon
the chlorirulted hydrocarbons in the feed stream. We conclude that microbial reductive
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dehalogenation of PCE can be used to remove chlorinated ethenes from some subsurface
groundwater aquifen.
DISCUSSION
Ptevious studies have demonstrated the anaerobic dechlorination of PCE using aquifer
solids and water in the laboratory (Parsons et al., 1984, Wilson et aL, 1983, Wilson et al., 1986,
and Suflita et aL 1987). To be a successful remediation method, PCE and its daughter products
must be completely dechlorinated in a contaminated site (Major and Hodgins, 1987). However,
previous laboratozy studies have indicated only limited success with the removal of PCE or its
daughter compounds using reductive dehalogenation (Suflita et aL, 1987, Freedman and Gossett.
1989). This work has demonstrated that PCE and its daughter products can be biodegraded to
concentrations which arc BDLs using EPA method 8240. Therefore, microbial reductive
dehalogenation is a potential remedial mechanism for halogenated compounds in groundwater
aquifers and deserves further invcstigation.t.
Ethene was the major metabolic product detected in these wells. To our knowledge, this
is the first demonstration that PCE can bt, degraded to ethene under sulfate-reducing conditions.
Toe produced ethcne is considered to be environmentally acceptable, since ethene has not been
associated with long-term toxicological problems and it is a natural-occurring plant hormone (Sims
et aL, 1991 ). Furthermore, elhene ~ known to further biodegrade to carbon dioxide under
aerobic environmental conditions.
VC was thought to persist in anaerobic environments and be more toxic to bacteria than
the parent compounds (Major and Hodgins, 1989). Our work does not support either theory. In
this work, after about 6 months of operation in Phase II, both VC and DCE appeared to have
biodcgraded to ethene i!lld ethane. Toe pattern of increase and disappearance of DCE and VC
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C:l0'39t!d 'OdlnN3 OJONOJ WOd~
• •
from Phase II 15 suggestive of microbial ouCCC3sion. We speculate that microbial sue.cession may
be a mechanism which completes reductive dehalogenation of DCE and VC to ethene and
ethane. From this assumption, it follows that bacterial consortia, rather than a single spa-ies,
would be required to completely dehalogenate PCE to ethene and ethane.
ACKNOWLEDGEMENTS
We thank Clifford Moczygemba, Mary Norvell, Bill Muldoon, John Coleman, Dr. Charles
Bleckmann, the Du Pont and Conoco organizations and Nancy Frank of the Texas Water
Cor:nm.wion for their dedicate efforts in support of this project.
REFERE."llCES
Freedman, D. L and J. M. GossetL 1989. "Biological Reductive Dechlorination of
Tetrachloroethylene and Trichloroethylene to Ethylene Under Methanogenic Conditions." Ann!.
Environ. Microbial. ~ 2144-2151.
Major, D. W. and E. W. Hodgins. 1991. "Field and Laboratory Evidence of In Situ
Biotransformation of Tetrachloroethene to Ethene at a Chemical Tranofer Facility in North
Toronto.• In Hinchee R. E. and R. F. Olfenbuttel (Ed•), On-Site Bioreclamation: Process for
Xenobiotic and Hydrocarbon Treatment pp. 147-178. Butterworth-Heineman, Stoneham, MA
Parsons, F., P. R. Wood P. R. and J. De.'-farco. 1984. "Transformationo of Tetrachloroethene ,md
Trichloroethene in Microcosms and Groundwater.' J. Am. Water Works Assoc. 7§, 56-59.
12
810"3:ltJd ·o~I~N3 OJONO) WO~o s2:r1 26, r J3a
• •
Sims, J. L, J. M. Suflita and H. H. Russell. 1991. "Reductive Dehalogenation of Organic
Contaminants in Soils and Ground Waters." EPA Ground Water Issue, EPA/540/4-90/054.
Suflita, J. M., S. A. Gibson and R. E. Beeman. 1988. • Anaerobic Biotransformation of Pollutant
Chemicals in Aquife.s". J. Ind113t. Microbiol. ~ 179-194.
Wilson B. II., G. B. Smith and J. F. Rees. 1986. "Biotran.sformation of Selected Al.kylben..enes
and Halogenated Aliphatic Hydrocarboos in Methanogenic Aquifer Material: A Microcosm
Study." Environ. Sci. Technol. m 997-1002.
WLlson, J. T, J. F. McNabb. B. H. Wilson, and M. J. Noonan. 1983. "Biotransiormation of
Selected Organic Pollutants in Groundwater." Dey. Ind. Microbial. ~ 225-233.
13
1710"39od "OolnN3 OJONOJ WO~3
• •
TABLE L Groundwater concentrations (µ.M) of PCE, TCE, DCE, VC, CA, ethane and ethene
in the Wells lN-1S, 2, 3, S, 6, and control well 15 on day 314.
(µM)
Feed to
Component/Well lN-1S 2 3 s 6 15
PCE 1.42 0.06 ND ND ND NS
TCE 0.72 0.09 0.19 ND ND NS
DCE ( cis-and trans-) 0.85 0.40 0.37 0.16 0.25 NS
vc 0.48 1.07 0.37 0.29 0.58 NS
CA 0.24 0.31 0.34 0.57 0.50 NS
Ethene 0.87 NS NS 0.71 1.75 ND
Ethane ND ND ND ND ND ND
Summation 4.58 ---3.08 -
ND == Not Detected. For PCE <.03 µ.M; 5 ppb. For TCE <.04 µ.M; 5ppb. For DCE <.05
µM; S ppb. For VC <.16 µ.M; 10 ppb. For CA <.16 µ.M; 5 ppb. For ethene <.35
µ.M; 10 ppb. For ethane <.33 µM; 10 ppb.
NS = Not Sampled.
14
£10"391:id sz:v1 zs, ~ J30
• •
TABLE :z. Concentrations of PCE, TCE, DCE, VC, CA, ethane and ethene in Wells lN-1S, 2, 3,
4N, 4, 4S, S, 6, and control wells 99 and 15 on day 426.
(:,.M)
Feed to
Component/Well lN-lS 2 3 4N 4 4S s 6 99 15
PCE 0.86 ND ND ND ND ND ND ND 3.98 NT
TCE 0.79 ND 0.06 ND ND ND ND ND 0.31 NT
DCE ( ci.s-and trans-) 0.66 0.06 0.19 ND ND ND ND ND ND' NT
vc ND ND ND ND ND ND ND ND ND' NT
CA ND ND ND ND ND ND ND 0.16 ND' NT
Ethene 0.75 0.46 0.57 1.46 1.43 2.11 0.50 l.71 ND ND
Ethane ND ND 0.3 0.3 ND ND ND ND ND ND
Summation 3.06 . -. -. . 1.87 . -
ND = Not Detected. For PCE <.03 µM; 5 ppb. For TCE <.04 µM; 5ppb. For DCE <.05
µ.M; 5 ppb. For VC <.16 µM; 10 ppb. For CA <.16 µM; 5 ppb. For ethene <.35
µM; 10 ppb. For ethane <.33 µ.M; 10 ppb.
NT = Not Tested.
ND' = Higher detection Jimiu since a 1 :4 dilution of sample wa.s made. Detection limits are
4 ti.mes that of ND values.
15
910'39t,d ·o~InN3 OJONOJ WO~~
• •
LIST OF FIGURE AND TABLE CAPTIONS
TABLE 1. OroUlldwater concentrations (µM) of PCE, TCE, DCE, VC, CA, ethane and
ethene in Wells 1N-1S, 2, 3, 5, 6, and control wells 99 and 15 on day 314.
TABLE 2. Groundwater concentrations (µM) of PCE, TCE, DCE, VC, CA, ethane and
ethene in Wells 1N-1S, 2, 3, 4N, 4, 4S, 5, 6, and control wells 99 and 15 on day
426.
FIGURE 1. Geologic cross section of the West Victoria Landfill.
Two sands underlay the landfill. The shallow zone A sand is thin, discontinuous,
and lies above the water table. The deeper zone B sand is the aquifer where the
pilot work wu perfonne.!.
FIGURE 2. Well flow diagrams used during Pha.se I and II of this study. Note the additional
wells used during Phase II (5, 6, 7N, 7, 7S).
FIGURF.S 3-6. Tctrachloroethenc, trichloroethene, dichloroethcne, and vinyl chloride
concentrations during Ph.ase L Note the pilot site was aerobic from day O to 203,
then an.aerobic from day 203 to 336.
FIGURES 7-9, Tctrachloroethene, dichloroethene and vinyl chloride concentrations during Phase
IL Note that the time ( days) restarts with zero for phase II.
Ll0"391:1d
Key Words in Context
Key Words and Chemicals
1) dehalogenation
2) biotransfonnation
3) chlorinated ethcncs
4) biotramformation
6) tetrachloroethcne
7) Tetracbloroetbylene
S)PCE
9) Benzoate
8 I 0 · 39t:ld
• •
92:vt 26, v )30
m
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w
lO
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0
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Lu
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0 z
0 u
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Ct:
u_
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(ft)
70
60
50
40
30
20
10
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-10
-20
-30
-40
-50
-60
-70
--
-----
---
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-
----
-

-
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'
Figure 1
Geologic Cross Section
West Victoria Landfill
Du Pont Victoria Plant
Horb:onlll Scale: _tcm a 20m
l 3--Primarily Clay c=]--Primarily Sand
--------------
== ZQne A Sand
-------
-

-
--
---
Zone B Sand
Sandy Clay/Clayey Sand ' , --
(m)
20
15
10
5
0
-10
-15
-20
• •
F/61./RE 2 ~ FLOW 0/AGRAMS Feed Tonk
4N
PHASE/ 4
4S
◄ GROUNOJi/ATER
FL.OW
IN
IS
·---------------------------------------------------------
7N
PHASE .I.I 7 +6
1sL.
SOOIG II'\ We:ter-:s
I I I
0 5 10
02:0. 39tid
Feed Tank
-tN IN
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◄ GR(lljNOWATER
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Control Circulation Site
LEGEND
Recover:,, Pipe = Del Iver:,, Pipe
<j Recovery We I Is t + Monitor-Wal I$
O Recharge We I le
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Figure 3
Tetrachloroethene .~ ....... ....
.. i"~f;:":.;::, •••• ;:-;; ••• -::--: ••.• ""···""···::-: •••• :,,: ..• :c:: ... c'::. ··""···"'"····""···-:-:-: .•• ::-: •.•• C,: •. ,,:-.•.• ::-:: ••• -::o .. ?.~1!>0:-: .. ::-c •.•• c:: .. :-:-:-.... ::;:.,~==_:::."!'.::(. I
1) ·······"····. --:::----·· II •••••••••••••
• II U loO fl 1U IU 1d lt-0 11,1 10 -IN IC Mf not al Ull
""
Figure 4
Trichloroethon
I ~ •••••••••..••••.•••••. : .•••• ~• •••••••.••••••••••.••••..•••• ?./~ ..... .
•
----·• --··
------··
!I M ~ W ,u 125 HI ,.. ,.. Ila N SM :t!1:1 "' HCI au 6W ,.,.
,. ..
,.,.
1, .•
•
---·· ----·· ----···
Figure 5
Dlchloroethene
~ _..,. 1
·•······· .... ·······•·•··•·•···••••••·•••• ..•• ···············"······· .::>-.
,.. ·········•······················----··························•·····
... •••••••••••••••••-••••••••••••••"'"'""'u•••••••••••••••• ••••••••••••••••••••••••••••••••
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... ...
...
• ll U N N Ill 1ft, HI lM 1111 112 JO) Pl ell "' J:IO m :JI ..,..
Figure 6
Vinyl Chlorld
.. ,-..t ·---
J .;. ...................... ._ ..................................... :?~Ii' .......................... -~.l --....... -.c>---··· ·····················•·········································
---••Ill --·· ___ , ..
,a. 4-........................................................................................... .
.... ····································--··················--···•····························
:l(IO ........................................................................................ .
I.OIi ...................................................................................... .
1) UM H 111 ltt 141 I~ 1M 1U ~ m ~~I~ W ~ ....
•
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4 '=1;..::: l 4 i::'.1::::1 ~ROM CONOCO ENUIRO.
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·•••••··•••·······•••·········•••••··• ········• Ml
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• f '
• • TOTAL
PAGE.022
PAGE.022 **