6
A research project on steam enhanced
Kmedi-aue-o (SER) for the ax-overv ofocnsc non-
aqueous phase liquid (i )NAl"'l.'; from fractured
limestone has been undertaken at the former
Lonng Air Force Rase Quarry sue in Lime stone.
ML' Participants IQ the project include the
Maine! fcparanentc4lmvironniaital Protar-aon,
IIS. KIWEegion 1, U.S. K;'A/National Risk
Mu afigcmeni Research La bora tor v i,NRMRL}..
and the Air Force Base Conversion Agency.
'i'he purpose of the research protect is to
determine if sieam injection can be used to
enhance the recovery of contaminants from
fractured Hrtiestotie.
A former quarry used for the disposal of more
(han 400 drums oi'spent solvents was selected
for this research, 'ilie fractured rock system at
the quarry is highly complex with three sets of
Iracuircs arid several iaults in or aroiind the
target area. While tetrachioroethene <;PCK) is
the main contaminant of concern, other
solvents and fuel components also arc present.
Rock chip samples were extracted. \viib aieihanol
and analyzed by HI "'A Method 8260 to determine
the contaminant distribution. The analytical
results sac-wed concentrations up to 100
nig/kg in traetures ranging 2rom 10 to I00ib:.:i
heknv ground surface (bgs). Transmissivity
testing done on 10-foot intervals showed that
the area geneiiilly lias vcr\- low pernieabilih,
ranging irorn 10"* to less than 10" rrr/scc.
Interconnectvity testing showed iiiat there is
limned iraeturc cc-nneciiviiy between the
eastern, middle-., and western pails ol'ihi: site.
(w;«holes torannga semicircle with a diameter
of approximately 40 ieel aS She eastern side of
the site were chosen ibr stetim injection lets
in the western side of the site weie used for
CMiraciLon. producing an exiraeiioa s\siem
approximately^ 60 feet wide and i 50 feet long. A
sy stein of 23 iiiennoeouple wel 1 s ai w eleetnca 1
resistance tomography (IZKI'ianplemeniedlioni
rum; boreholes u-us ;i».;d So monitor iomperuiure
and steam flow. The sparsely fractured, iow--
transrnissivitv nature of the site limited the
amotinl ol sleam that could be iatec-ted, thus.
three exltaction wells thai were not prochicing
significant amounts of contaminants were
converted to steam miection wells after 30 days
of injeeiion. Operai.k>nai techniques such as
infection pressures, air iniecrion.. and draiv-down
of around-«-"ater levels to create pressure
c\chag were tested to determine Jlieir eilects
on imcciion ami extraction rales. The total
iieriodofthe injection was limited by the bijdget
to 83 days followed bv 7 dayrs of extraction.
Daily ellluent samples of both the vapor and
aqueous phases she-wed that extraction rates
initially were low and generally decreased
during the Itrst three weeks of ihc
demonstration, much as \vonkl be expected
during conventional juanp and treat operation
Subsurface tempera Hire and ERT monitoring
indicated that the steam, and hot water
condensair followed rather narrow paths in the
limestone, and that only a small fraction of the
rock was heated, to su.-am teaipeniture. liven
these small temperature increases, however.
significantly increased the effluent
Tbertna: Technology
Tested for Contaminant
Recovery
and
Sponsor Fieiti Test of
Cosolvent-Enhanced
DNAPL Removal
page 1
2
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Irniovaiion()ftice < I'K)}is
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I concentrations in both the vapor and aqueous
! phases. Aqueous concentrations of gasoline
I range organ ics, dies:.:! run
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80% k:\vcr dissolved PCh concentrations
than belore treatment. \v:ih an average PCI:
concentration of approximately 15 mg/L.
NRMRI. and SHRDP are preparing a
comprehensive summary of these
demonstration results, as \\;el! as the results
of other innovative DNAPI, remediation
technologies recently tested at the DNT8.
As part of a cotnptunenstve ellbil to ad.dtuss
ground-water contamination ai the TJ.S.
! !te[Tart1 a t of Knergy Savani id i Rh er Si is; (SRS)
near Aiken. SC. a biospaiajng system began
operating: us JW) at the site's s;-i Hilary landfill
; SLF). Riospargmg was sclccicd 10 address ihc
trichloioethene (TCh)v vinyl chloride, and TCH
breakdown products in the ground water
underlying flic landilli By 2002, biosparging.
treatinent hud reduced ground-water
concei :tratioi :s ofvinvl ehloride and 'i 'CH Ą.itliin
ih:.: irci-iimmit zone by "(>% aoti 75%,
respectively.
! ,arae arnounts of wastes were gerieiated at the
SRS di-iiig consiriidion aiulosxTaiioa ol'ihc
iiicslitv. Cafeteria and oihce wastes, sewage
skajc,e, iniscellaiK»jjs constnaction materials,
and debris routinely were disposed at the 70-
i«.«e nniinsxi SLF liwuilk! early 1970s to the rmJ
1990s. After the discovery of ground-water
contamination beneath the landfill, the main
stx-hoii and the w.nithcai expanse ion area oi ihc
lantiilli \VCK covered wilh an cngineeied cap.
Maxin w, \ coi !cent«itioi« of1, "iny 1 oh loride and
TCK art interior landfill w«llAwere480 ug/1. and
31 liji'L, respectiv'uiy.. prior to biosyxirging
treatment.
1 hree s^zriiiisjuQt hyttosaiob^io units ntniedii:
die lanttfili: aniippemisj-st iincoiiiinedai|iiiier, a
confinjne unit,and a lower aquifer. The depth to
die water tarfe ranges ftwn 30 ft to 60 ft l>gs.
(jround-watcr tlow in the area of (lie landfill is
primarily horizontal, with an upward flow
component where it discharges to a large
wetland ad ween! to ilk! bndiill. Beneath Hit:
landfill contaminants were idcntiiiedc-nlv in the
upper rx"si tic n is of the shal low actui fer. Nun si ica I
modeling estimates that tfie advective
transport lime itom ihc mam sec-lion of ihc
landtill to a de-«A ngr-adicni biosparging well
between the landfill and wetland is 11 years.
with anotlier tiiree years tor discharge to the
wetland. Figure 2).
atsda (/UO-ii surcxaied well side-santteni oi'tiis.: :
landfill ibr treating vinyl chlondc. Each well ;
consists of a six-incli-dianietei" outer steel !
casing,, screen, and an inner toiir-incli, Ing.h- j
density, polyelhvlcae imer. Both \vclls rely on !
a central air compressor unit (rated lor a j
maximum airflow of 540 cfin'; but o:«rate !
indepcntkrnily to aoeommodaic tidleteni :
mjeetion configurations. !
Optimisation testing prior to full-scale !
operauons dernonsiraied. thai addii tonal |
nutrients were ncct.ted for the iiovvngradtcni !
well area, while air injection was adequate for j
bioremediation in the f.ide-graciient welt area. !
Lvlcihane (0.7%) was mjcoied into the j
downgradient well to stimulate growth of;
n letliai KJ-OK id i? ing < met! anotivf >ic) 01 gan isnis. !
'I iieseorganians pre-duee i!ie sirong o\idi^ing j
agent (monooxyiEeriase i needed tor complete !
mineralization of' 1CK. As expected..;
methanotropic degradation of TCH was !
consi rained to the sai!>un
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! Methane laiechoii was terminated in. January
I 2U(jl because TCIi eoacenfr aliens bad
! decreased substantially and numerical
I modeling predicted that the benefit of
! additional injection was limited.
! Both wells currently tieat vinyl chloride bv
I serving, as aerobic No-degradation pathways
! andbv cohancing voialdizal ion. Air ism;eclcd
I into the wells once even' two weeks for 48
! continuous hours at a rate of 220 serin in the
I downgradient well and 250 sdni in She si.de-
! gradient well. Alter 24 hours, nitrous oxiiie
! arid triethv I phosphate nittrienls (0.048% arid
I 0 005% of total air/month, respectively'.! are
! injected in the dew agradical well Lor 8 hours.
I Vinyl chloride ooooeaf raiioas haw coniiaued
! to decrease over the past year, with maximum
I concentrations during the first quarter of'2003
! reaching 80 tig/L in an interior landfill
! iTioiiitoiirip well and i 1 us/!, in a pun it-of-
I compliance we 11 at t lie base of the landfi 11.
! Grouoti-walcr moiicis predict thai pnaiary
I contaminant concentrations will not exceed
! ground-water protection standards due to
I ongoing plrvsied. and bio Logical processes
! oi'natural attenuation. Since concentrations
! have decreased to regulator,' limits for this
I RCR A facility, plans are underway to suspend
! operation of the biospatying system anil io
I eoiita roe groin id-water rnoni tonnp tor several
! years. Maintenance of the biosparaing
I svstem \\ lit continue in the event monitoring
! results indicate that resumed operations arc
! \varranted. Additional infoniiationregaidinp
I enhanced bioremediation and monitored
! rmutrai atlcmtahoiial the SRS SLF is available
I on-line ;- Ljcpi-iiiiM'nl oj Energy-'SRS
: i'Nfij-725--ff>-l8 or
North
A piloi siLki}1 \vas compleied in laniiiiry 2uU3
at die Silresim Superfund site in Lowell. MA,
to evaluate the effectiveness of electrical
resistance heating (HRH) technology in
treating contaminated soil and ground water.
The U.S. EPA/Region 1 and Army Corps of
Hngineers will use the pilot results to determine
the feasibility and cost of implementing this
technology on a full-scale basis forremediation
of the vadose and saturated zones.
Concentrations of vapor extracted over three
months of treatment indicated that an
estimated 1,500 pounds of V( )€s were removed
I rom approximately 1,000 cubic yards of soil.
As a result of past industrial waste reclaiming
operations, the subsurface soil and ground
\vater at this 5-acre site contain high
concentrations of VOCs, including TCE, PCE,
;. 1,1 -trichloroethane, metliy lene chloride, and
BTEX. Pre-treatmenl sampling revealed
extensive contamination with total VOC
concentrations exceeding 800 mg/I, in ground
water and !,()()() mg/kg in soil. The geology
consists of fill and fine sand extending to
approximately 10 ft bgs with an approximate
hydraulic conductivity of 3.9 x 10"'cm/sec. A
varved clayey sill layer with an estimated
hydraulic conductivity of 5.5 x lO^ein/sce exists
at 10-30 feet bgs. Below the clayey silt is a layer
of silly and very fine sand with an estimated
hydraulic conductivity of 1.1 x 10"1 cm/sec.
The pilot was conducted in a 25-ft-diameter lest
cell with heating electrodes extending 40 ft bgs
(Figure 3).' I 'he site was covered by a 40-by-40-ft
cap consisting of a gravel vapor collection layer.
a poh/vinylidene fluoride membrane to protect
the cap from chemical attack, 1.5-incli.R-11 foam
insulation to reduce heat loss to the surface,
and a reinforced HI )PK membrane for weather
protection. Fourteen electrodes were used to
deliver six-phase, 240-kW power into the
subsurface. The electrodes were installed as
six pairs in a hexagonal pattern. Hach pair
consisted of a shallow electrode providing heal
at 2-10 feet bgs and a deep electrode providing
heat at 10-40 ft bgs. Two neutral electrodes
were installed at similar depths in the center of
the hexagon. All electrodes doubled as vapor
extraction wells to capture the liberated
subsurface contaminated vapors.
The electrodes consisted of vertically slotted,
carbon steel with graphite granules as a
conducting filter pack. Drop lutes were installed
I continued on page J/
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in iho \\clis of each shallow ciecirodc and
connected to the vapor extraction system to
'"sUirp" water and maintain a constant water
lc\'el. In addition, electrolyte drip lines were
installed in ihe L'dicr pick lo mauiiam adeiu tale
moisture for electrical conduction. Power was
delivered to each deep electrode through a
parallel eonaection from us paired shallow
electrode I'he shallow electrodes dre\\"
approv.rnateh 20anpsofcun;enr,whiJe;:hedee?'i
ones drew approxnnaieK1250 amps.
'I he vapor collection system consisted of pry\].niaieh' 48,000 ixninds ot'
granular aeii\'aied carbon \\i\s used fc-r vapor
ireatnient diirina the pilot project
Four thermocouple sinngs \\vrv insia.lled made
ariiiiinrrKdiaicix1 oiiisitle ilie electrode arra\: liic
interior strings \\rere placed ecji.«d;stant fmm the
electrodes, \\here heatrntt \\i\s least eilecuve.
installed at 5-li inter^'als i:o a dq;tli of 45 feet.
Ground temperatures readied steam
len!|:vr;iU(res:nadq:ihofappix>xin!aie!v 40leei,
and inereaseii io 115°C at 35 leet. Alien eight
weeks of beating., temperatures in the target
interval tor the subsurface treatment zone
achieved boiling temperatures. Measurements
of arnbieni vapor eonoenlra lions using Held
instruments indicated no nricontiolled vapor
emission from die electrode array tla'ouelioue
ilie pilot test operations.
Overall, soil conducted electricity at levels
higher than anticipated, possiblv due to the
presence ot' buned rrK.:tal \\'tisle. Minor stray
electrical volaaes were ohsei'ed outside the
News
is on the NET!
://'www. go v/li o
http://cfuin.org
Technology A^'U'.v and 'trend*
welcomes readers" coiruncnls
and contributions. Address
correspo nde nee to :
'. S . linvi romncn (;< 1 Proicc-i : on Ageuicy
Ariel RJOS Building
i 2(;(; Pennsylvania Aye, N W
\Vashinoton, i \1 20460
Phone: 703-603-7 lc>9
.ti'ii s. /o3--u03 -V 1. 3 ;>
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Solid Waste and
Emergency
(5102G)
EPA 542-N-03^003
Way 2003
Issue No. 6
Environmental Protection Agency
National Service Center for Environmental Publications
P.O. Box 42419
Cincinnati, OH
First Class Mail
EPA
Permit No. G-35
Official Business
Penalty for Private Use $300
[continued from page 5]
electrode array during system startup. Placing a
chain-link mesh outside the array and grounding
it to a distant monitoring well remedied this
problem. In addition a pro-pilot resistivity survey
would have helped to assess the potential for
undesired stray voltage during treatment.
A significant setback was encountered during
the second month of operation when cracks in
the CI'VC piping (leading from the electrodes
to the vapor header) resulted in an atmospheric
release of steam and vapor. Operations were
shut down for several days but resumed after
the degraded €P VC was replaced with flexible
chemical-resistant hose. This unexpected
condition appeared to result from a
combination of excessive heat, pressure, and
chemical attack from a variety of contaminants.
Post-test analysis showed that shallow
ground-water contamination (<24 feet bgs) in
the treatment zone decreased more than 99%,
and deeper ground-water contamination (24-
Additional analysis of the pilot results will
determine whether HRH technology could be
used to achieve project cleanup goals that were
not met through 1997-1998 implementation of a
soil vapor e\JraeUon (SVli) system. Although
SVH treatment resulted in the removal of
approximately 12 ions ol subs; irlaeeVOCs over
a !4-rr;orilli period, wneenlralionsinlhev;;dose
and saturated zones remained significantly
higher than their maximun contaminant levels.
Results of the EMI pilot suggest thai this
technology can increase mass removal
efficiencies in both the vadose and saturated
zones more eftectivaly than traditional SVH.
The ERII pilot cost approximately $1.6 million,
including $30,000 for electrical power and $50,000
for vapor treatment. Modeling based on total
VOC concentrations exceeding 10 me/kg
indicates that 1.02 million Ions of soil require
additional treatment.
Contributed by Sharon Hayes,
U.S. ERVRegion 1 (617-918-1328 or
hayes.sharon@epa.gov) and John
Scaratnuzzo, Tetra Tech FW, Inc.
(617-457-8297 or jscaramuzzo@llj\vi.com)
hi the March 2003 'technology News ana'
Trends article, "ONAPL Treatment
Demonstration Completed at Cape
Canaveral,'" the contributors believe use of
the terms "'treatment efficiencies"' and
"cleanup efficiencies" may be mislead;!ip due
to uncertainties in mass removal estimates for
the SP1I demonstration. The appropriate
language is '"apparent reduction/" The
SFH cost of "$164" for each, kg of 1 CH
removed or destroyed should read "$64."
6 The 18!
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