A newsletter about soil, sediment, and groundwat
Technology
News & Trends
EPA 542-N-14-002 | Issue No. 66
Summer 2014
This issue of Technology News & Trends highlights characterization and remediation strategies to
address contaminants of emerging concern (CECs), which are chemicals or materials characterized by a
perceived, potential, or real threat to human health or the environment or by a lack of published health
standards. A contaminant also may be "emerging" due to the discovery of a new exposure pathway to
humans, or the development of a more stringent regulatory standard. New toxicity information on frequent
contaminants such as trichloroethylene (TCE) and tetrachloroethylene (PCE), for example, can lead to
re-emergence of concern.
CECs typically are associated with certain classes of products, as ingredients or generated during
processing or manufacturing, such as:
• Pharmaceuticals and personal care items.
• Steroids and hormones.
• Pesticides.
• Nonlyphenols, octylphenol, and alkylphenol ethoxylate (APEs) compounds.
• Polynuclear aromatic hydrocarbons (PAHs).
• Bisphenol A (BPA) and plasticizers.
• Polybrominated diphenyl ether (PBDE) and perfluorinated compound (PFC) fire retardants.
• Nanomaterials.
The risks to human health and the environment due to a CEC's presence, frequency of occurrence or source
may be unknown. CECs also may persist for a long time in the environment because their structure is
resistant to chemical or biological degradation. In water, concerns may relate to discovery of contaminants at
levels significantly different than expected or which were previously undetected.
FEATURED ARTICLES
Characterization and Testing: Bench-Scale Research on Options for In Situ Treatment of
Perfluorinated Compounds
Contributed by Victor Medina, U.S. Army Engineer Research and Development Center, and Linda Lee, Purdue
University
The U.S. Army Engineer Research and Development Center (ERDC) and Purdue University, with support from
the Air Force Civil Engineer Center, are developing an in situ method for treatment of groundwater contaminated
with perfluorinated compounds (PFCs). The research uses perfluorooctane sulfonate (PFOS) and
perfluorooctanoic acid (PFOA) as model compounds. Both have been identified in the groundwater of several
military sites at concentrations above EPA's 2009 Provisional Health Advisory levels of 0.4 micrograms per liter
(ug/L) PFOS and 0.2 ug/L PFOA. The potential use of PFOS and PFOA in firefighting exercises at several
hundred U.S. Air Force, Navy, and Army installations is the primary driver behind the bench-scale research
project. The goal is to develop a viable option for treating PFCs in situ, which has not been possible using
traditional treatment methods. Results proved that modifying conventional ultraviolet (UV) radiation treatment to
activate persulfate with heat degrades at least up to 2,500 ug/L PFOA in contaminated groundwater, although
PFOS is recalcitrant to the treatment. Supplementary trials using 0.1-0.5 grams (g) zero-valent iron (ZVI) with 1-
2% palladium, however, degraded PFOA and PFOS by up to 43% in 48 hours.
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Figure 1. Basic components of a firefighting training area (US
DOT 2010).
Aqueous film-forming foams (AFFFs)
containing PFCs have been demonstrated
to be highly effective at fighting
hydrocarbon fuel fires as a consequence
of their ability to block oxygen and
suppress volatile vapors from flammable
solvents. Most military facilities that
routinely service aircraft maintain
firefighting training areas in order to allow
emergency personnel to train with AFFFs
and other firefighting methods to prepare
them to fight actual aircraft fires. Over 575
firefighting training facilities exist at Air
Force, Navy, and Army installations
around the world.
Aviation firefighting training areas typically
comprise a circular pad of crushed rock,
fire-resistant concrete or brick, and a drain
to catch overflow (Figure 1). Groundwater
data collected in 1999 at Wurtsmith Air
Force Base (Michigan), Tyndall Air Force
Base (Florida) and Naval Air Station Fallen (Nevada), where RFC concentrations ranged from below detection
limit to over 14,000 ug/L, suggest that any military site where AFFFs have been used is likely to have a dissolved
plume containing PFCs.
The chemical properties of PFOS and PFOA inhibit most conventional treatment approaches. The strong carbon-
fluorine bond and the shielding of the carbon-carbon bonds by fluorine atoms, each with three pairs of non-
bonding electrons, contribute to the stability of terminal PFCs and increase their resistance to degradation. Past
studies have indicated that these terminal PFCs are recalcitrant to a range of conventional treatments including
bioremediation, ozonation, ZVI reduction, and Fenton's chemistry reactions, or are not possible to treat in situ.
The ERDC/Purdue study chose heat-activated persulfate oxidation modeled upon the successful experimental
application of UV radiation-activated persulfate (appropriate for only ex situ treatment) on a laboratory scale. Past
studies with UV-activated persulfate have indicated rapid degradation of PFOA in aqueous solution by persulfate
radicals with half lives of about one hour. Degradation products included fluoride ions, sulfate ions, carbon
dioxide, and shorter chain perfluorinated alkyl acids (PFAAs), which can be further degraded sequentially by
persulfate radicals. Persulfate requires a relatively low soil
oxidant demand and promotes the formation of free radicals
such as the sulfate radical anion (SO4~*) and hydroxyl free
radical (OH*), which are highly stable under normal
subsurface conditions and travel effectively through the
subsurface into target contaminant zones. However,
degradation of fluorinated compounds may also result in the
production of hydrofluoric acid, which could hinder further the
activated persulfate process.
Glass reaction vials (40-mL) contained aqueous solutions of
either PFOS or PFOA at a concentration of 50, 100, 500, or
2,500 ug/L and persulfate concentrations from 0 to 20,000
milligrams per liter (mg/L). Oxidant concentrations were
chosen based on previous work conducted with
contaminants of emerging concern. Well-mixed samples
were exposed to temperatures ranging from 20°C to 60°C for
up to 336 hours. Changes in PFOA and PFOS
concentrations, as well as any detected metabolites, were
quantified.
i.o
0.8
.—
'i/i
ro
-Q
_QJ
O
J,
u°
0.6
0.4
TS 0.2
0.0
50
100 150
Time (h)
200
250
Figure 2. Oxidative degradation of PFOA (100
Ijg/L or 0.241 uM) by 10,000 mg/L sodium
persulfate in unbuffered solutions at
temperatures ranging from 30°C to 60°C.
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PFOA was degraded by heat-activated persulfate, and
higher temperatures resulted in quicker removal (Figure 2).
Higher persulfate concentrations were also found to lead to
more complete removal of PFOA and shorter-chain PFAAs,
with most successful results achieved with a persulfate
concentration of 20,000 mg/L at 50°C (Figure 3). At 1,000-
2,000 mg/L persulfate, about half of the original
experimental PFOA concentration remained after 48 hours.
Though pH declined with higher persulfate concentrations,
lower pH had no appreciable effect on the results.
Heat-activated persulfate degradation of PFOA produces
increasingly shorter chain PFCs, one carbon difluoride (CF2)
group at a time referred to as an "unzipping" process.
Intermediate products recovered during the degradation
process included perfluoroheptanoicacid,
perfluorohexanoic acid, perfluoropentanoic acid,
perfluorobutanoic acid and trifluoroacetic acid. Most of the
intermediates were degraded with 10,000 mg/L persulfate
after 72 hours at 60°C and after 48 hours at 50°C, with only
the primary metabolite, trifluoroacetic acid, remaining.
o 10
20 30 40
Time(h)
50 60 70
Figure 3. Oxidative degradation of PFOA (100
[jg/L or 0.241 fjM) by sodium persulfate
concentrations ranging from 1000 mg/L to
20,000 mg/L at 50°C in unbuffered solutions.
Addition of 1,000 ug/L ethylbenzene, as a representative
hydrocarbon common to military sites, to PFOA samples with 10,000 mg/L persulfate did not reduce PFOA
degradation rates. Based on these findings, it is expected that elevating persulfate concentrations would lead to
degradation of PFOA and certain hydrocarbon-based contaminants. In addition, using a single application of
10,000 mg/L persulfate effectively degraded 6:2 fluorotelomer sulfonate, a precursor compound commonly found
in AFFF mixtures, suggesting that heat-activated persulfate treatment may effective in degrading compounds
produced through the fluorotelomerization process.
The study found that activated persulfate, though feasible to use in the field at concentrations examined, did not
lead to degradation of PFOS. The recalcitrance of PFOS to treatment presents an issue, since both PFOS and
PFOA are found in AFFFs and are likely both present in groundwater where AFFFs were used. One potential
solution may be the use of ZVI amended with a catalyst such as palladium. Preliminary research on using 0.1-0.5
g ZVI with 1-2% palladium at room temperature to degrade both PFOA and PFOS showed promising results.
Degradation of both PFCs up to 43% within 48 hours was achieved at room temperature with 0.1 g ZVI and 1%
palladium. The method may be appropriate to in situ application in permeable reactive barriers. The method is
being studied further as a new SERDP (Strategic Environmental Research and Development Program) project
ER-2426 to optimize the properties of nano-bimetals for increased reactivity and delivery within zones of PFC-
contaminated groundwater.
New Remediation Technology: Treating 1,4-Dioxane with Synthetic Media
Contributed by Thomas K.G. Mohr, University of California-Davis, and Frank R. Niles, Massachusetts Department
of Environmental Protection
A synthetic media system using a carbonaceous adsorbent has operated at an industrial site in Waltham,
Massachusetts, since late 2011 to treat 1,4-dioxane in extracted groundwater. The system was installed due to
inability of an existing air stripper to reduce the 1,4-dioxane to concentrations below the State's 0.3 ug/L
discharge limit for 1,4-dioxane. Since integrating the synthetic adsorbent, 1,4-dioxane has been detected above
the laboratory detection limit in the facility's effluent only once. Chlorinated VOCs also have consistently met
discharge limits during the same operating period.
1,4-Dioxane is a contaminant of emerging concern that is most commonly found at sites where 1,1,1-
trichloroethane (TCA) was used as a vapor degreasing agent. It was added to TCA as a stabilizer. 1,4-Dioxane's
apparent widespread occurrence at industrial sites also is attributed to its use in manufacturing processes, such
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as those used to produce polyester resin and polyethylene terephthalate plastics, cellulose acetate membranes,
and some pharmaceutical products.
1,4-Dioxane is classified as a probable human carcinogen by the U.S Environmental Protection Agency (EPA),
and it has toxic effects on the kidney and liver. EPA's 2010 toxicological review of 1,4-dioxane recommended a
steeper cancer slope factor, resulting in a 2012 health advisory level for 1,4-dioxane of 0.35 micrograms per liter
(ug/L). Accordingly, several states (including Massachusetts) have lowered their drinking water advisory levels
and site cleanup levels for 1,4-dioxane.
Data supporting EPA's third Unregulated Contaminant Monitoring Regulation identified 1,4-dioxane at
concentrations greater than the prescribed Method EPA 522 method detection limit (0.07 ug/L) in 11.9% of 7,171
samples from 851 public supply water sources. This rate of detection is exceptionally high for an organic
anthropogenic contaminant in drinking water. While the concentrations detected are generally very low, 3.9% of
water systems tested have 1,4-dioxane detections exceeding the EPA health advisory level (0.35 ug/L) . The
widespread occurrence of 1,4-dioxane in drinking water reflects its ubiquitous presence in groundwater.
Treating 1,4-dioxane is a challenge due to its very low Henry's law constant and complete miscibility. It also has a
low organic carbon-water partition coefficient (K0c)_and is immune to abiotic breakdown under ambient conditions.
1,4-Dioxane is generally resistant to natural biodegradation at meaningful rates. Similarly, air stripping is
ineffective, and effectiveness of granular activated carbon (GAG) is limited at high flows and low concentrations
due to 1,4-dioxane's low K0c-
The primary solution for 1,4-dioxane remediation has been various
forms of ex situ advanced oxidation. Pump and treat technology
followed by ex situ treatment with catalyzed ultra-violet light
oxidation technology (such as PhotoCAT™) or ozone peroxidation
technology (such as HiPOx™ or ClearDioxane™) has been favored.
These systems require careful monitoring and maintenance to
adjust for variable source water and operating conditions.
Challenges include onsite ozone generation, delivery and storage of
hydrogen peroxide, frequent change-out of costly ultraviolet lamps,
pH sensitivity, possible formation of bromate or hexavalent
chromium, and competitive consumption of free radical scavengers
such as alcohols, acetone, and iron as well as carbonate alkalinity.
Figure 1. Carbonaceous adsorbent, with
non-dusting spherical form.
-,TM
The carbonaceous adsorbent used at the Massachusetts facility has
demonstrated success in removing 1,4-dioxane occurring in a wide
range of concentrations for water treatment elsewhere. The product (AMBERSORB1"" 560) is produced through
partial pyrolysis of a sulfonated styrene-divinylbenzene copolymer, which yields a hard adsorbent with high
surface area and high porosity (Figure 1). When compared to broad-spectrum GAG, which consists of non-
synthetic material, this adsorbent provides more specificity and selectivity for many non-polar compounds. As an
engineered product, it offers lower batch-to-batch variability in adsorption capacity.
Studies by the manufacturer suggest that the material's
effectiveness relates to its transitional pores, pore shape,
and smaller particle size, as well as its higher
hydrophobicity when compared to GAG (Figure 2). This is
a significant advantage in vapor-phase applications for
removal of volatile organic compounds (VOCs) because
the product retains its capacity in high-humidity vapor
streams. The lower adsorption potential of water results in
a net higher adsorption potential for non-polar
compounds. In liquid-phase applications, this
hydrophobicity contributes to the higher sorption capacity
for organic contaminants, including 1,4-dioxane and
chlorinated VOCs. Although 1,4-dioxane is miscible in
water, it is both a non-polar and polar solvent due to its
transitional dipole moment and dielectric constant in
different conformations.
500
400
BOO
S.200
u
100
0
GAC
- - AMBERSORB
0 10 20
30 40 50 60 70
Relative Humidity (%)
80 90 100
Figure 2. Water adsorption isotherm for GAC versus
synthetic media.
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Vendor comparisons also suggest the adsorption
capacity of the synthetic media is roughly an order of
magnitude higher than GAG at the lower end of the
equilibrium concentration range (Figure 3), the range
of 1,4-dioxane concentrations typically encountered
in contaminated groundwater.
For most 1,4-dioxane treatment systems using this
product, a total of three adsorbent beds is preferred
to provide continuous treatment (Figure 4). During
operation, the dioxane-laden groundwater passes
through two online beds until breakthrough occurs at
the lead vessel. The lead vessel is then taken offline
for regeneration. The lag vessel is placed in the
lead position and the standby vessel is placed in
service in the lag position.
1000
100
'u
S.
10
0.1
0.01
-»- GAC
-•- AMBERSORB
0.001 0.01
0.1 1 10 100 1000 10000 10000
Equilibrium Concentration (mg/L)
Figure 3. GAC and synthetic material adsorption
isotherms for 1,4-dioxane.
Figure 4. Typical process flow using AMBERSORB adsorbents for groundwater treatment.
In contrast to GAC, this adsorbent is typically regenerated in place, using low-pressure steam. Regeneration of
the offline bed is usually accomplished by passing low-pressure steam through the bed, countercurrentto the
direction of the process stream flow. After exiting the bed, the steam/1,4-dioxane flow is condensed and
decanted. Upon regeneration with 10 to 12 pore volumes of steam, the bed is returned to the standby position.
To further minimize the waste volume needing offsite disposal,
the highly concentrated condensate from the steam regeneration
process is often "superloaded" through a small vessel containing
GAC. Although GAC has a relatively low adsorptive capacity for
low concentrations of 1,4-dioxane, a relatively high adsorptive
capacity exists at the elevated 1,4-dioxane concentrations
present in the condensate (Figure 3). Processed water from the
superloader is directed back to the head of the pretreatment train
and the small GAC vessel is periodically sent offsite for
reactivation.
At the Waltham site, this synthetic media system treats 15 gallons
per minute (gpm) of groundwater to address a targeted portion of fi 5 stomge units containing the synthetic
the groundwater plume. The groundwater contains an average media system used at the waltham site.
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1,4-dioxane concentration of 20 |jg/L and total chlorinated VOC concentration of 3,000 |jg/L. Water is pumped in
an up-flow mode through multiple synthetic media vessels operated in series. The system is housed inside two
portable storage containers (Figure 5).
Since synthetic media operations started, 1,4-dioxane concentrations in the effluent have been consistently non-
detect at <0.61 ug/L, with one exception (Figure 6). After changing to EPA Method 522, the 1,4-dioxane
concentrations in the effluent also have been consistently less than the analytical laboratory's method detection
limit (<0.04 ug/L). In addition, chlorinated VOCs have been consistently removed to concentrations below 1.0 ug/L
for the entire 26-month operating period.
100
^^ o
j °%b
2 10 Incomplete
^ Regen
| * 1
4) 2 ' cnt ) :'t Mfj
O ^*
2^oi
=
I
^ n m
i 0-O-C
\ , S-.
~ -O - - &-0- C- 60- e~ 0- - es -o-o
EPA Method 522
(ND <0.04 |ag/L)
System Restart
Permit Limit
Measurement Date
Figure 6. Influent and effluent 1,4-dioxane concentrations at the Waltham site.
Replacement of the site's existing 100-gpm air stripper with a full-scale synthetic media system is anticipated to
be complete by September 2014 to address other portions of the groundwater plume. Cost analysis of
alternatively positioning an Ambersorb unit after the existing air stripper showed that use of the synthetic media,
alone, would be more cost-effective in removing the 1,4-dioxane as well as the VOCs at a comparable rate of
throughput.
To be published fall 2014: Woodard, S., Mohr, T.K.G., and Nickelsen, M., 2014. Synthetic Media: A Promising
New Treatment Technology for 1,4-Dioxane. Remediation Journal, J Wiley.
Full-Scale Treatment: Electrical Resistance Heating Resolves Difficult Removal of CEC Source Area
Contributed by Sunny Becker, Washington Department of Environment, and Lynette Stauch, TRS Group, Inc.
Cleanup at the Fox Avenue site in Seattle, Washington, has involved implementing several pilot- and full-scale
technologies over the past 20 years to address soil and groundwater contamination from numerous chemicals,
including contaminants of emerging concern (CEC) such as tetrachloroethylene (PCE), trichloroethylene (TCE),
pentachlorophenol (PCP), and dioxins. Full-scale in situ thermal technology involving electrical resistance heating
(ERH) was applied in early 2013 after limited success with other technologies to address a significant source area
with dense non-aqueous phase liquid (DNAPL) extending 65 feet below ground surface (bgs). Analysis of over
200 samples in late 2013 indicated that ERH use resulted in a 99% reduction of the estimated mass of
contaminants of concern (COCs) in the primary source area and significant COC reductions (more than 90%
overall) in the associated dissolved plume. Bioremediation as a polishing step is now progressing; residual
subsurface heat in the treatment area is promoting reductive dechlorination of contaminants, and injections of
emulsified soybean oil scheduled to begin later this year are expected to further enhance declorination in the
source area as well as the downgradient plume. Control of this 500-foot-wide groundwater plume is critical in
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preventing recontamination of seeps that discharge groundwater into the Lower Duwamish Waterway Superfund
site.
The Fox Avenue site occupies about 2.5 acres in an industrial area of south Seattle. Since the late 1930s, the site
(previously known as Great Western Chemical) has been home to coke- and oil-fired furnace operations followed
by chemical/petroleum product blending, repackaging and distributing facilities. In addition to PCE, TCE, and
PCP, primary COCs in groundwater include c/s-dichloroethene (c/s-DCE), vinyl chloride, total petroleum
hydrocarbons (TPH, including mineral spirits) and BTEX (benzene, toluene, ethylbenzene, and xylenes).
Groundwater flows at an estimated rate of 0.1 to 2 feet per day from the site and discharges to the Lower
Duwamish Waterway at a point 400-500 feet downgradient. The lithology consists of sands and silts overlaying a
confining silt layer that creates a perched aquifer extending from 10 feet to 75 feet bgs. DNAPL was observed in
wells.
Remedial actions began in 1990 with the removal of underground storage tanks. From 1995 throughl 996, a soil
vapor extraction system (SVE) and a groundwater pump and treat system operated on a pilot-scale basis.
Minimal reductions in COC concentrations prompted additional investigations and pilot testing of chemical
oxidation using potassium permanganate as well as dual-phase extraction from 1997 through 2000. Peroxide
injection and biosparging were recommended in a 2000 supplemental feasibility study but not implemented. In
2005 and 2006, three rounds of permanganate injection and expansion of the SVE system resulted in additional
COC concentrations reductions in soil as well as groundwater; however, significant COC rebound was observed
in the groundwater by 2007.
Monitoring indicated that naturally-occurring reductive dechlorination was occurring in the groundwater plume but
persistently stalled, generating significant concentrations of c/s-DCE and vinyl chloride. Enhanced reductive
chlorination (ERD) was initiated in 2009 through injections of waste sugar, a solution of sucrose and other
carbohydrates derived from off-specification food-grade sugars. Between 2009 and 2013, 10 injection events at
various locations were administered to intersect the plume and reach the entire depth of the aquifer.
Extensive source area characterization (including membrane interface probe profiling) also was conducted in
2009 to determine the final remedy for source area soils, which were estimated to still contain approximately
10,000 pounds of solvent mass. ERH technology was selected to treat soils in the primary source area. The ERH
system was designed to treat approximately 42,000 cubic yards of soil with the remedial goal of achieving a
combined average concentration of 10 mg/kg PCE
and TCE. Prior to ERH application, the average
PCE + TCE concentration was 141 mg/kg in a
treatment area that included the vadose zone soil,
upper silt horizon and lower silt horizon with spot
concentrations exceeding 4,000 mg/kg.
The ERH design anticipated that the completed
waste sugar injections would enhance reductive
dechlorination in the groundwater plume onsite and
downgradient. The design also accommodated
conditions and infrastructure supporting ongoing
industrial activities, including deep contamination
below an active building, shallow contamination
under an active rail spur, utility corridors, existing
stormwater management trenches, and closed
tanks (Figure 1). Other influential factors included
the presence of mineral spirits, high groundwater
flux, variability in soil resistivity values (such as 40-
120 ohm-meter versus 5-18 ohm-meter), and
effective recovery of steam and vapors released
from deeper soils.
Figure 1. Locations of ERH electrode field and supporting
remedial equipment at the Fox Avenue site.
Hollow-stem auger drilling was used to install a total of 158 ERH electrodes at an average spacing of 15 feet in
five distinct treatment areas (Figure 2). Forty-four electrodes were installed within below-grade trenches, which
allowed the facility to continue operating in all but one area. Facility operations were suspended in the treatment
area having the majority of existing mineral spirits ("Area 4"); in this area, density of the electrodes was doubled to
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•nrMtmairt ATM and I
OFFICE nnilAtest Rail (Area 1> 3.200yd3
(*•'* Loadng Dock (Area 2) 1,300 ytf
-... E^] East Rgj and Flamrrables (Area 3) 3,900 •
IMlRail, MW, and SE Shalow & Deep (Area 4) 21,300yd3
FrariAifcatfw shediProducllon Deep Only (Area 5J 7.BDD >/&
F/gure 2. F/Ve treatment areas distinguished by site conditions and past activities; ERH treatment was designed
to reach shallow depths in areas 1 through 3, shallow and deep soils in area 4, and only deep (65 feet bgs) soil of
area 5.
increase the energy intensity and associated volatilization during
ERH. To address soil under the rail spur and building, the
electrodes were placed at an angle (Figure 3).
The ERH system included nine field transformers applying an
average operating power input of 1,410 kW, as well as 140
subsurface temperature sensors. Vapors from the boiling liquids
were recovered in a steam and air flow averaging 1,500
standard cubic feet per minute (scfm) and separated into two
separate streams that were handled by two condensers
operating in parallel. Vapors from the treatment area with the
highest COC concentrations were then treated by thermal
oxidization with an acid gas scrubber, and vapors from other
areas were treated in granular activated carbon (GAG) vessels.
The generated water was discharged to the sanitary sewer
under a King County discharge permit.
Figure 3. Electrode placement below
railroad spur and building.
Active heating began in early January
2013 and ended in the middle of May
2013, when the average subsurface
temperature reached a maximum of
99.2°C. Heating rates were highest
during the initial two months (Figure
4). Various system parameters were
monitored throughout operations,
including time, energy input,
subsurface temperature, extracted
vapor concentrations and
steam/condensate production. Use of
a dynamic soil sampling strategy
enabled heating shutdown in an area
where cleanup goals were met, which
allowed heating efforts to be
redirected into other areas still
containing elevated CVOCs. Over the
full operating period, a total of 7.2
megawatts of power was applied to
the subsurface. Approximately 66%
1/26 2/15
in
Date
3/27 4/15 S/6 W26
Figure 4. Rate of soil heating during ERH application in 2013.
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of the power was applied in Area 4, where approximately 80% of the estimated source-area contaminant mass
existed.
Performance evaluation
indicated ERH treatment
removed approximately 10,000
pounds of chlorinated solvents
and over 19,000 pounds of
mineral spirits, based on pre-
ERH estimates. Of the mineral
spirits, 10,330 pounds of TPH
was removed through the GAG
vessels and 9,230 pounds of
TPH was destroyed through the
thermal oxidizer. During the 4.2
months of ERH operations, the
average combined PCE and TCE
concentration in soil decreased
from an average of 141 mg/kg to
ERH Sample Location
0.53 mg/kg, a 99.9% removal of
estimated mass in the source area
(Figure 5). As expected, the
remaining PCE and TCE exist in the area exhibiting the highest pre-ERH concentrations (Figure 6). Limited
sampling at one location also indicated an unexpectedly high (65%) reduction in PCP concentrations in soil.
Although ERH implementation focused on soil remediation, it also reduced PCE + TCE concentrations in
groundwater by about 90% immediately following active heating, with further reductions observed in subsequent
months during the cool-down phase.
GP 86
GP-70A
GP-74
GP-42
GP-75
GP-35
Figure 5. Comparison of PCE + TCE concentrations before and after ERH
application.
Pre-thermal - Maximum at Any Depth
PCE4TCE cone, in
o 10QI-100
* 100.01-1,000
• 1,000-10.000
PCE-tTCE Cone, in
1-ID
10-100
ii.c-1.11 in
1,000-10,000
TreaffnentAress
Legend
• DonfirmatJori Soil Soring
1^3 PrE-thErmal > 1 ppm Contou
PCEtTCE Cane in
Figure 6. Site-wide reduction in PCE + TCE concentrations due to ERH application.
Post-heating groundwater samples collected via Geoprobe® drilling equipment have been used to establish
groundwater conditions and plan injection of emulsified soybean oil (ESO) to stimulate anaerobic microbial
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processes for additional dechlorination of CVOCs in groundwater. Temperature trends indicated that the optimum
temperature for ERD (35-40°C) was reached in approximately 12 months after ERH shut down. Fourteen new
injection wells and two existing injection wells have been installed for administering ESO later this year as a
source-area remediation polishing step and to promote ERD in a corner of the downgradient groundwater plume.
Indoor air of facilities operating onsite and at a nearby property is now being tested to ensure that the State of
Washington cleanup standards are met for PCE and TCE as well as vinyl chloride. Onsite and targeted offsite
sampling in 2009 and 2010 had identified PCE and TCE vapor intrusion at several locations. In 2013, the State's
standards for these indoor contaminants were adjusted to reflect EPA's new toxicity information.
A four-well SVE system will be used in a northwest corner of the site to remove PCE remaining in the vadose
zone, which would otherwise act as a long-term source of groundwater contamination. Existing asphalt or cement
caps on approximately 90% of the site's ground surface prevents direct contact with soil or sediment
contaminants, including dioxins and residual PCP, that will remain onsite with deed restrictions.
CLU-IN Website: Contaminant Focus
This issue area of CLU-IN bundles information associated with the cleanup of individual contaminants and
contaminant groups. The information is presented in categories such as policy and guidance, chemistry and
behavior, environmental occurrence, toxicology, detection and site characterization, and treatment technologies.
Contaminant and contaminant groups addressed in this online area include CECs, such as arsenic, chromium
VI, 1,4-dioxane, dioxins, perchlorate, polychlorinated biphenyls, and trichloroethene.
Fact Sheet Series: Emerging Contaminants and Federal Facility Contaminants of Concern
EPA recently updated a series of technical fact sheets addressing contaminants of concern that present unique
issues and challenges at contaminated federal facility sites. Each contaminant-specific fact sheet briefly
summarizes the compound's physical and chemical properties, its environmental and health impacts, related
federal and state guidelines, and applicable detection and treatment methods. Contaminants addressed by these
fact sheets include: 1,2,3-trichloropropane (TCP); 1,4-dioxane; 2,4,6-trinitrotoluene (TNT); dinitrotoluene (DNT);
hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX); N-nitroso-dimethylamine (NDMA); perchlorate; polybrominated
diphenyl ethers (PBDEs) and polybrominated biphenyls (PBBs); tungsten; nanomaterials; and perfluorooctane
sulfonate (PFOS) and perfluorooctanoic acid (PFOA).
New Edition: Superfund Remedy Report
EPA's Office of Superfund Remediation and Technology Innovation released the 14th edition of the Superfund
Remedy Report. The report compiles data on overall remedy selection and remedies for source materials (such
as soil and sediments), groundwater, and surface water since 1982, with a focus on Superfund remedial actions
selected in fiscal years 2009 through 2011. This edition also documents the types of remedies selected for
sediments and vapor intrusion mitigation.
Recent Interagency Meeting: FRTR Meeting on Emerging Contaminants
The Federal Remediation Technologies Roundtable (FRTR) works to build a collaborative atmosphere among
federal agencies involved in hazardous waste site cleanup. Since 1990, the FRTR has strived to share
information about cleanup technologies; discuss future federal directions of site remediation programs and their
impact on the technology market; interact with similar state and private industry technology development
programs; and form partnerships to pursue subjects of mutual interest. At its November 2013 meeting, the FRTR
focused on emerging contaminants and related issues; a summary of the meeting and individual presentations
are available from the FRTR website.
New Guidance: Groundwater Remedy Completion Strategy; Moving Forward with the End
in Mind
EPA's Office of Superfund Remediation and Technology Innovation partnered with the Agency's Federal Facility
Restoration and Reuse Office in developing a new guidance document, Groundwater Remedy Completion
Strategy. The guidance is intended to help focus resources on the information and decisions needed to
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effectively complete groundwater cleanups involving active and/or passive groundwater restoration remedies
under CERCLA. Topics addressed in the guidance include design of site-specific remedy evaluations,
development of performance metrics and collection of associated monitoring data, and a process for conducting
remedy evaluations.
Chemical Assessment: TSCA Work Plan Chemical Risk Assessment; Trichloroethylene:
Degreasing, Spot Cleaning and Arts & Crafts Uses
In June 2014, EPA released a final risk assessment for TCE. The assessment identified health risks from TCE
exposures to consumers using spray aerosol degreasers and spray fixatives. It also identifies health risks to
workers when TCE is used as a degreaser in small commercial shops and as a stain removing agent in dry
cleaning. The final TCE risk assessment was developed as part of the Agency's Toxic Substances Control Act
(TSCA) Work Plan, which identified chemicals for review and assessment of potential risks to human health and
the environment. TCE is the first chemical to complete the work plan risk assessment process under TSCA.
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