5
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 o
                         /A newsletter about soil, sediment, and groundwater characterization and remediation technologies
                        Issue 55

This issue o/Technology News and Trends highlights assessment and remediation of sites where
past use of tetrachloroethene (PCE) at drycleaners resulted in environmental contamination.
Topics include commonly used technologies such as soil vapor extraction (SVE), bioremediation,
and in situ chemical oxidation (ISCO); renewable energy to power these technologies; and studies
on controlling contaminant vapor mitigation.
             Three-Pronged Remedial Approach Used at Highly
                          Contaminated Site in Florida
  Approximately 14% of the 314 drycleaning
  sites assessed by the  Florida Drycleaning
  Solvent Cleanup Program (DSCP) to date
  have groundwater with PCE concentrations
  exceeding 15,000 Jlg/L (10% of the aqueous
  solubility of PCE). These sites are considered
  highly contaminated and likely contain dense
  non-aqueous phase liquid (DNAPL) in the
  saturated zone, making them the most costly
  and challenging to remediate. One such site
  is the Holiday Plaza French Cleaners in
  Pembroke Pines. Since 2005, the cleanup has
  involved excavation followed by SVE and,
  more recently, bioremediation. Sampling
  results compiled earlier this year indicate a
  99% reduction  in  source  area PCE
  concentrations due to the cleanup measures.

  Drycleaning operations using  PCE were
  conducted at this  shopping center facility
  from 1982 until 1999 when it was converted
  to a dry drop-off operation. In early 2004,
  direct push technology, a mobile laboratory,
  and a sonic drilling rig were used to collect
  and analyze soil and groundwater samples.
  Results  revealed two contaminant source
  areas: a  stormwater drainage system within
  a service alley behind the drycleaning
  building, and soil beneath the floor slab (in
  the upper 30 feet of the saturated zone near
  the former drycleaning bay).

  The  highest contaminant concentrations
  detected in sediment collected from the
  stormwater drain were 6 mg/kg PCE, 19
  mg/kg trichloroethene (TCE),  5.5 mg/kg
                           cis-1,2-dichloroethene (DCE), and 2.5 mg/kg
                           vinyl chloride  (VC). In groundwater, the
                           highest concentration of PCE was 135 mg/L,
                           which suggested the presence of free-phase
                           PCE.  PCE degradation  products were
                           detected in groundwater at concentrations
                           reaching 17.2 mg/L TCE, 90.4 mg/L cis-1,2-
                           DCE, 4.9mg/L /rara-l,2-DCE, and6.5 mg/L VC.

                           The lithology consists of medium-grained sand
                           with limestone stringers to approximately 34 feet
                           below ground surface (bgs). From 34 to 38 feet
                           bgs, fossiliferous limestone overlies limestone
                           extending to 90 feet bgs. Depth to groundwater
                           at the site ranges from 5 to 6 feet bgs.

                           In August 2005, cleanup was initiated
                           through an interim source removal involving
                           excavation around the readily  accessible
                           storm drain. The target area covered about
                           18 by  56 feet to  a depth of 5 feet except
                           around the drain, where excavation extended
                           to 10 feet bgs. Approximately  120.6 tons of
                           contaminated soil  and sediment were
                           removed, and the stormwater system was
                           reinstalled. After excavation, a 94% decline
                           in total VOC  concentrations in groundwater
                           was measured in a water table monitoring well
                           near the drain.

                           In May-July 2009, the  SVE system was
                           constructed to  address contaminated soil
                           under the drycleaning building and part of
                           the service alley. Three vertical wells were
                           installed, two beneath the building floor slab
                                             [continued on page 2]
                                                                                     September 2011
                                                                                 Contents
 Three-Pronged
 Remedial Approach
 Used at Highly
 Contaminated Site
 in Florida
 Renewable Energy
 for Drycleaner
 Cleanups
                                                                                             pagel
page3
 Gravity-Feed as an
 Alternative to
 Pressurized
 Injections for ISCO    page 3
 Evaluating the
 Effects of Vapor
 Migration  Control
 Systems             page 5
     Online Resources
The State Coalition for
Remediation of Drycleaners
(SCRD) offers online profiles
summarizing remediation
systems at 177 drycleaner
sites. Other SCRD search-
able databases or online
publications address common
issues at drycleaner sites
such as the variable chemistry
of solvents, vapor intrusion,
and suitable site character-
ization technologies. To
learn more or subscribe to
the SCRD's semi-annual
newsletter, visit:
www.drvcleancoalition.org/.
        Recyc led/Recycl abl e
        Printed wilh Soy/Carrola Ink on paper llral
        contains at least 50% recycled fiber

-------
[continued from page 1]
and the third in the alley. Each well was
constructed of 4-inch-diameter PVC pipe
screened from 1 to 4.5 feet bgs. Through
use of a 15-hp rotary blower, the system
operates at an average flow rate of 150 cfm
with an operating vacuum of 1.3 psi. Well
offgas is treated in a  140-pound granular
activated carbon (GAC) vessel.

In situ biostimulation was selected as the
groundwater remedy due to evidence that
reductive dechlorination occurs at the site
anaerobically. Indicators included low
dissolved oxygen (ranging from 0.2 to 0.7
mg/L)  and an  oxidation-reduction
potential of-201 to-101 mV (near the ideal
range for  reductive  chlorination). The
presence of ethene  and ethane as PCE
degradation products, along with existing
microbial populations known to degrade
chlorinated hydrocarbons (Dehalococcoides
ethenogenes), provided additional evidence.

The carbon-rich amendment  chosen to
stimulate bioremediation was an emulsified
oil substrate consisting of soybean oil,
fast-release sodium lactate, food additives,
extracts, and water. Since installation of
injection wells beneath the shopping
center was  infeasible, a groundwater
recirculation system using two  1.5-hp
submersible pumps was designed to
distribute the reagent across the source
area. The recirculation  system consisted
of four 5-inch-diameter wells in two-well
clusters, one for  injection and one for
recovery. One of the wells in each cluster
was screened at a shallow depth (10-30 feet
bgs) and the second was screened 20 feet
deeper. The injection cluster was positioned
adjacent to the former dry cleaning bay with
the extraction cluster approximately 100 feet
away, on the opposite side of the building.
The anticipated extraction rate for each well
was 30 gpm, with an estimated 41 days for
the solution to disperse under the building.

In July 2009, 275 gallons of substrate and
24,960 gallons of water were injected into
the shallow-zone well, yielding an injection
concentration of 1.09% (equivalent to a
carbon application  concentration of 7,903
mg/L). For the deeper zone, 275 gallons of
substrate and 36,480 gallons of water were
injected to achieve a concentration of 0.75%
(5,426 mg/L carbon). Vitamin B12 was also
injected in each well to provide additional
microbial nutrition. The injection occurred
at a rate of one liter of substrate per minute
followed by chase water at 30 gpm.

Shortly after concurrent startup of the
groundwater recirculation system, the
annular seal for the shallow injection well
failed. A second shallow injection well was
immediately installed but its seal also
failed. As  a result, operations were
modified to allow future injections/
recovery at lower flow rates, and the
shallow recovery well's 1.5-hp pump was
replaced with a 0.75-hp pump.  Subsequent
shallow-zone recovery rates were reduced
from approximately 32 gpm to  18 gpm, but
injection rates in the deeper wells remained
at approximately 38 gpm.

A second injection was conducted in April
2010. A total of 357.5 gallons of the same
1 60 000
140 000 -
^ 120 000 -
3.
*"~"* inn nnn -




20,000
0 i
Jun
-+- PCE
**\ -•-TCE


/\ -K- cfe-1,2-DCE
/ 1 -*- frans-1,2-DCE
.r \. % Vinyl chloride


-08 Dec-08 Jul-09 Jan-10 Aug-10 Feb-11 Sep-11
substrate and 23,500 gallons of water were
injected in the shallow zone to yield a 1.5%
concentration (10,867 mg/L carbon). In the
deeper zone, 357.5 gallons of substrate and
61,000 gallons of water were injected for a
0.58% concentration (4,225 mg/L carbon).

Fouling occurred in the shallow recovery
well four months after the second injection
and in the deep recovery well 1 -2 months
later. As a result, recirculation was
suspended.  Through September 2010, the
shallow recirculation  system  had
recovered/re-injected approximately 4.5
million gallons of water and  the  deep
recirculation system recovered/re-injected
approximately 15.4 million gallons.
Extracted groundwater was treated in
two 2,000-pound GAC vessels operating
in parallel.

Significant  declines  in contaminant
concentrations,  along with apparent
conversion  of PCE to daughter products,
indicate that the  soil and groundwater
treatment   successfully  accelerates
reductive dechlorination.  As of January
2011, comparison  of pre-treatment
contaminant concentrations in the source
area monitoring well near the storm drain
(where previously excavated) showed a
99.8% reduction of PCE, 98.9% reduction
of TCE, 91.3% reduction of cw-l,2-DCE,
and 70.9%  reduction of VC (Figure  1).
Monitoring of the second source  area,
beneath the building floor slab,  showed
PCE was reduced by 99.2%, TCE by 95.6%,
and cw-l,2-DCE by 71.8% , with a 323%
increase in  VC (from a detection limit of
620 mg/L to 2,000 mg/L).

The Florida Department of Environmental
Protection  (FL  DEP)  anticipates
                 [continued on page 3]
                                                                             Figure 1. Sampling results from one
                                                                             representative well at Holiday Plaza French
                                                                             Cleaners since July 2008 SVE startup
                                                                             suggest a cumulative effect of the emulsified
                                                                             oil substrate injections, which were
                                                                             conducted in July 2009 and April 2010.

-------
[continued from page 2]

continued operation of the SVE system
and a  third  injection  following
rehabilitation of the biofouled recovery
wells later this  year. Costs for  the
project, which is  administered  and
funded under the  State's DSCP, total
approximately $750,700 to date, including
site assessment  ($185,800), excavation
($141,700), design and construction of
the SVE and biostimulation/recirculation
systems ($248,200), and operation  and
maintenance ($175,500).
Contributed by Bill Linn, FL DEP
(william. linn(a),dep.state.fl. us or 850-
245-8939) and Guy Frearson, AECOM
USA, Inc. (guy.frearson&.aecom. com or
954-745-7211)
                                 Renewable Energy for Drycleaner Cleanups
Site remediation at Busy Bee Laundry in
Rolla, MO, illustrates how renewable
energy can be used to power the cleanup
equipment needed at many drycleaner
facilities, including those where ongoing
operations prevent use of obtrusive
technologies. Solar energy is captured at
the facility by a 540-watt photo voltaic (PV)
array that directly powers a 400-watt piston
pump extracting PCE-contaminated
groundwater.  The  system  extracts
approximately 0.25 gallons of groundwater
per minute from a depth of 3 5 feet bgs and
transfers it to reactivated GAC vessels
inside the laundry facility. Since January
2011  start-up, the system has  removed
nearly 1.7 kg of PCE. Latest  results of the
demonstration also suggest that use of a
comparable low-costPV array  could pro vide
significant benefits at other hazardous
waste sites, including abandoned sites in
remote  locations or where continuous
long-term dewatering is optimal.

To maximize capture of solar energy, the PV
system includes a passive  tracking
mechanism (Figure 2). Selection of a pump
that could operate on direct rather than
alternating current eliminated the need for
an inverter. The system also includes a timer
that temporarily suspends pumping when
the rate of groundwater flow drops below a
pre-determined level, to allow well recovery.
Supplemental recovery time as well as
additional energy and cost efficiencies were
gained by designing a low-flow system that
could effectively treat the groundwater while
accommodating unavailability of power
during periods of low solar radiation.

During the first six months of operation, the
system extracted and treated 32,112 gallons
of groundwater at an average rate of 200
gallons per day. Performance  analysis also
indicated approximately 800 kWh of grid-
supplied electricity were avoided through
use of onsite solar energy. Based on the
local electricity provider's fuel mix, this
avoidance corresponds to an air emission
reduction of 3,500 pounds of carbon dioxide,
11 pounds of sulfur dioxide, and 4 pounds
of nitrogen oxides each year.
Capital costs for the PV system totaled
approximately $3,600, including four PV
panels, the passive tracker, and a linear
current booster. Project costs were
covered under the Missouri Dry cleaning
Environmental Response Trust (DERT)
Fund with cooperative funding  from
Missouri University of Science  &
Technology (MO S&T).

Monitoring and maintenance of the PV
system is  conducted by the university's
faculty  and graduate students. More
information about the project and other
cleanups  administered  under  the
Missouri  Drycleaning Environmental
Response  Trust Fund is available from
the Missouri Department of Natural
Resources (MO DNR).

Contributed by Vicky Kugler, MO DNR
(vicky.kugler(a)dnrmo.gov or 573-522-2093)
and Curt Elmore, Ph.D., MO S&T
(elmoreac(q)mst.edu or 573-341-6784)
                                      Figure 2. The passive solar tracking
                                      system at Busy Bee Laundry relies on
                                      transfer of a fluid (freon) from the east
                                      side to the west side of the PV mounting
                                      rack, as the sun continues to heat a
                                      reservoir throughout the day.
The Illinois Drycleaner Environmental
Response Trust Fund (IDERTF) recently
applied ISCO to treat heavily contaminated
soil and groundwater at the Norgetown
on Rand drycleaner in Arlington Heights,
IL. Since the majority of contamination
existed  below the active drycleaner
facility, a gravity-feed process offered a viable
alternative to traditional oxidant delivery
methods involving pressurized injections.
Use of the gravity-feed system was expected
to eliminate oxidant backflow (daylighting)
and avoid creation of preferential pathways,
which resulted during an earlier pilot study
                     Gravity-Feed as an Alternative to Pressurized Injections for ISCO
in which chemical oxidant was injected at
pressures as low as 120 psi. In contrast, the
maximum pressure of the  gravity-feed
system was equivalent to approximately 6
psi. Limited success  of the pressurized
injection pilot study was attributed to
                 [continued on page 4]

-------
[continued from page 3]
contaminant location in the soil above the
water table.

A total of 21 groundwater monitoring wells
were installed during the  site investigation.
Pre-treatment PCE levels in soil  and
groundwater were measured as high 24,000
mg/kg and 979 mg/L, respectively. PCE
biodegradation products such as TCE, DCE,
and VC were detected in samples but in much
lower   concentrations;  the  highest
concentrations in soil and groundwater
were 13.74 mg/kg and 15.42 mg/L for TCE,
7.30 mg/kg and 17.98 mg/L for DCE, and
0.47 mg/kg and4.18 mg/L for VC.

The water table at the site is approximately
5.3 to 6.9 feet bgs. Soil in the target zone
primarily  consists of a  sandy  clay layer
extending 12-16 feet bgs that overlies a clay
layer at 16 feet bgs, although isolated areas
contain significant sand content at 6 to  12 ft
bgs. Shallow soil (0-20 feet bgs) exhibits a
hydraulic conductivity averaging 2.71 cm/day
(32.4 ft/yr) and hydraulic  gradient of 0.018.
The estimated porosity of soil is 0.20.

The selected oxidant sodium permanganate
(NaMnO4) was delivered through 22 injection
wells screened at 5-10 and 10-20 feet bgs. In
addition, 10 of the monitoring wells (screened
at 5 -15 feet and 10-20 feet bgs) were retrofitted
for oxidant delivery. The 32 injection points
were intended to deliver oxidant throughout
an approximate 1,000-ft2 area.  Field
observations during the initial stage of
gravity feeding suggested a radius of
influence (ROI) ranging from 2.5 to 6  feet.
Prior to beginning the injections, the
estimated ROI at each injection point was
used to determine a suitable volume of oxidant
for each point.

The injection process used six 65-gallon
storage drums filled with NaMnO4 solution
and positioned on 3-foot-high platforms
inside the drycleaner building, near the
dry cleaning machine.  Each drum  was
connected to an injection point by a single
gravity feed line (Figure 3). Once an injection
point was fed with the desired  amount of
oxidant, the next  injection point  was

                                       Figure 3. ISCO at the Norgetown
connected to the feed line until the process
covered all 32 injection points.

Flow rates varied significantly from injection
point to inj ection point, ranging from 0.07 gal/hr
to about 80 gal/hr. Equipment failure  due to
fitting corrosion and feed-line air bubbles was
experienced during the initial stage of gravity
feeding but was easily corrected by replacing
the fittings and rearranging the feed lines.

The  first stage of treatment was completed
over 59 days in March through May 2010,
during which time a total of 360 gallons of
10% and 2,487 gal of 20% NaMnO4 solution
was  injected  via 27  injection points. A
confirmatory site investigation in August
2010  showed that although both the
contaminant concentrations and plume size
had  significantly  decreased,  residual
contamination  levels   in  soil   and
groundwater at five sampling points were
higher than the remedial objectives. As a
result, an additional round of gravity-feed
injections was conducted over 55 days in
September through October 2010 at 10
injection points. Atotal of 2,300 gal of 3.3%
NaMnO4 solution was fed to the remaining
hotspot area during this follow-up injection.

No daylighting was observed, suggesting that
the majority of oxidant had reached the target
zone with minimal development of preferential
pathways. Based on the oxidant feed rate and
water table changes in nearby monitoring
wells, contact time between the NaMnO4 and
                                       of various lengths to reach 32 injection
                                       points inside or directly outside the
                                       drycleaner building.
PCE was estimated at 3 -5 days in the vadose
zone and at least 25 days in the  saturated
zone.  In contrast, the earlier pilot project
involving pressurized injections showedno
change in the water table, which suggested
a significantly shorter contact time (less than
one day) in the vadose zone.

Sampling conducted approximately 60 days
after gravity feeding ended indicated a 99%
reduction in PCE concentrations in soil
(from 24,000 mg/kg to  160 mg/kg) and
groundwater (from 978 mg/L to 6.6 mg/L
and from 500.5 mg/L to 19 mg/L). Afinal
confirmatory site investigation was
conducted shortly thereafter with nine soil
borings and groundwater samples from 12
monitoring wells.  Only one soil boring
showed residual  TCE, at a concentration
of 3.4 mg/kg, without residual DCE or VC.
Groundwater sampling detected PCE
degradation byproducts in only one
monitoring well, where concentrations
increased to 3.5 mg/L from 2.73  mg/L for
TCE, to 3 3 mg/L from 2.6 mg/L for DCE, and
to 0.65 mg/L from 0.045 mg/L for VC. These
results suggest  that  indigenous  PCE-
reducing bacteria remain active.
The cost to implement gravity-feed ISCO
was approximately $195,000, including
$24,000 for confirmatory site investigations
and $ 17,000 for well abandonment. System
maintenance also accounted for a significant
portion of the project cost due to the need
for two to three site visits each week and the
additional safety precautions required for
storing large volumes of the chemical oxidant
over several months.

Contributed by Juho So, Ph.D., IL
DERTFAdministrator,  Williams & Co.
Consulting (iso (aiwillconsult. com or
800-266-0663) and Greg Dunn,  IL
EPA (greg.dunn(a),illinois.gov or
217-785-2359)

-------
                        Evaluating the Effects of Vapor Migration Control Systems
Vapor mitigation studies at the Sharon
Cleaners facility  in Saratoga Springs.
NY, and the Blue Ribbon  Cleaners
facility in Tallahassee, FL, revealed that
vapor mitigation systems can induce
unexpected effects on subsurface vapor
migration. The study at Sharon Cleaners
found that an active system installed
at the facility  helped limit vapor
migration toward offsite buildings. At
Blue Ribbon Cleaners, an evaluation  of
the lingering asymptotic soil vapor
concentrations found the cause to be
the soil vapor extraction (SVE) system
drawing PCE into the subsurface from
the facility, which was using PCE for
drycleaning operations.

The initial objective of the New York
State Department of Environmental
Conservation (NYSDEC) six-month
study of vapor intrusion mitigation  at
Sharon Cleaners  was to compare the
effectiveness  of  a passive open-pipe
system and a passive wind-powered
system with that of an active electrical
vacuum  system.  An active  sub-slab
suction system driven by a 91- to 129-
watt electric fan  was installed at the
drycleaner and at  a residential building
located 40 feet to the south. The two
passive mitigation approaches  were
incorporated at a second residential
building  located 15 feet to the east  of
the drycleaner.
Data from sub-slab samples collected
between November 2009 and May 2010
and during the remedial investigation in
April 2008 show that a more significant
reduction in PCE can be achieved through
an active system. At both active  systems,
PCE concentrations declined from 3,000-
23,000 ug/m3 to below 5 ug/m3. At the
passive system, PCE concentrations
decreased from 1,600-9,400 ug/m3to2.1-
330 ug/m3 between November and March.

Because the passive and active systems
were  close to each other, NYSDEC
evaluated whether the active system was
influencing the results of the passive
system.  To do  so,  all systems were
temporarily shut down in March 2010 and
were reactivated and operated separately
over a 2-month period. PCE concentrations
at the passive  system during this period
ranged from 32 ug/m3 to 2,900 ug/m3 during
passive treatment alone and between 0.9
ug/m3 and 30 ug/m3 during sole operation
of the active system at the  drycleaning
facility  (see Table 1). Based on these
findings, NYSDEC concluded  that the
active system was  altering vapor flow
patterns  and contributing to the PCE
removal at the residential building with
passive mitigation. NYSDEC anticipates
continued operation of the passive and
active systems at the drycleaner  and both
residential  buildings   until   PCE
concentrations within the indoor air and
sub-slab soil vapor reach levels set by
the New York State Department of Health.

At Blue  Ribbon Cleaners, FL DEP
conducted an 18-day study in April 2011
in response to consistent detection of
low-level asymptotic PCE concentrations
in the extracted soil vapors. Initial PCE
concentrations in the  extracted soil
vapors were 11,000 ug/m3 when the SVE
system began operating in September
2009. Within one month following SVE
startup, PCE concentrations decreased to
below 1,000  ug/m3  and remained
asymptotic throughout the next year of
active remediation. The objective of the
study was to determine whether this
observation was a result of volatilization
of PCE from vadose zone soil or, possibly,
mass flux migration from the drycleaner
to the vadose zone.

The  SVE system consisted of  seven
vapor extraction wells, four of which
were installed  in the sub-slab directly
beneath the drycleaner. The estimated
ROI  of each vapor recovery well was
approximately  30 feet. A 15-hp blower
provided  a  vacuum beneath  the
drycleaning   building.  The  study
examined PCE concentrations in vapor
at three locations: inside the drycleaner,
in a vapor extraction well located beneath
the drycleaner, and in the extracted  soil
vapors.  Photoionization detectors

1 PCE Concentrations (|ug/m3) Passive Treatment System Site f

Remedial Investigation
Baseline Sampling
Open-Pipe
Wind Turbine
New Baseline
Rebound Assessment
Open-Pipe Only (Active Off)
Active Only (At Sharon Cleaners;
Passive Off)
4/1/2008
11/5/2009
12/9/2009
1/6/2010
3/11/2010
4/14/2010
4/27/2010
5/11/2010
SS-1
4,800
9,400
4.6
280
2.1
25
68
1.2
SS-3
NS
1,700
32
2.6
30
1.2
32
0.9
SS-7
NS
6,100
5.4
20
330
50
2,900
30
IA
7.3
8.5
2.1
2.1
2.6
1.7
2.3
2.3
OA
<1
NS
<1
<1
1.3
<1
<1
<1
SS Sub-Slab Vapor Point OA Outdoor Air
IA Indoor Air NS Not Sampled

                                                                                            [continued on page 6]
                                                                                         Table 1. Samples collected
                                                                                         at the residential
                                                                                         building containing the
                                                                                         passive treatment system
                                                                                         show that active
                                                                                         mitigation at Sharon
                                                                                         Cleaners exerted a
                                                                                         greater influence on
                                                                                         PCE concentrations
                                                                                         offsite than the offsite
                                                                                         passive system.

-------
                                              Solid Waste and
                                              Emergency  Response
                                              (5203P)
                                 EPA 542-N-11-004
                                 September 2011
                                 Issue No. 55
United States
Environmental Protection Agency
National Service Center for Environmental Publications
P.O. Box 42419
Cincinnati, OH 45242
             Presorted Standard
             Postage and Fees Paid
             EPA "
             Permit No. G-35
Official Business
Penalty for Private Use $300
 [continued from page 5]
 were used to evaluate continuous PCE
 concentrations at each of the three vapor
 monitoring locations.

 Samples indicated that PCE concentrations
 ranged from 39,340 ug/m3 to 79,350 ug/m3
 inside the drycleaning building, with the
 higher value observed during the day
 when business was open, and the lower
 value when business was closed. Samples
 collected from the vadose zone indicated
 a similar trend.

 The opposite trend was  observed in
 samples collected from extracted soil vapor.
 PCE concentrations,  which ranged from
 350 ug/m3 to 980 u.g/m3, were higher when
 the drycleaner was closed and lower when
 the facility was open  and operating. PCE
 concentrations in extracted soil  vapors
 fluctuated in a cyclic (nocturnal) pattern
 with a 4-hour time lag in the PCE mass flux
 from the active drycleaner through the
 concrete slab, increasing four hours after
 the drycleaner closed and decreasing four
hours after the drycleaner was open and
operating. The average PCE mass inside
the drycleaner during operational hours
was estimated to equal to the mass
recovered by the SVE system when the
drycleaner was closed (about 80 g),
suggesting that the concrete slab provides
little attenuation for vapor migration.

FL DEP concluded that the distinct cyclical
trends in PCE concentrations observed
during the study indicated that  PCE can
migrate from an active drycleaner and be
captured by an SVE system. Based on these
findings, FL DEP shut  down  the SVE
system immediately following the study.
The site is currently being monitored for
natural attenuation as specified in the site's
remedial action plan.

Contributed by Aaron Cohen, FL DEP
(Aaron. Cohen(a)dep. state.fl. us or
850-245-8962) and Brian Jankauskas,
NYSDEC (bfjankau(q),gw.dec.state.ny. us
or 518-402-9620)
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   State Drycleaner Programs
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sites. Each program administers a
legislatively-funded trust to help
prioritize, finance, and implement
these efforts. More information about
the program and process in each
state is available through:
www.drvcleancoalition.org/state.cfm.
EPA is publishing this newsletter as a means of disseminating useful information regarding innovative and alternative characterization and treatment
techniques or technologies. The Agency does not endorse specific technology vendors.

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