\
u
/A newsletter about soil, sediment, and groundwater characterization and remediation technologies
Issue 43
This issue of Technology News and Trends (TNT) provides selected updates on pilot
projects and treatability studies described in past issues. Some technologies moved toward
full-scale application at the study sites, while others were supplemented or replaced by one
or more technologies, such as injections of vegetable oil or sodium lactate, soil mixing with
zero valent iron, air sparging, and mulch reactive barriers.
Explosives Remediation at Pueblo Chemical Depot Changes Course
Treatment of soil and groundwater
contaminated by energetic compounds has
been underway since 1997 at area of interest
(AOI) 3B of the Pueblo Chemical Depot
(PCD) in Colorado. AOI 3B is part of the
source of an explosives-contaminated
groundwater plume. Initial work involved
excavation and onsite composting of soil to
address the contaminant source. In 2001, a
pump and treat system using granular
activated carbon and ion exchange began
treating groundwater with high concentrations
of RDX, 2,4-DNT, and nitrate near the PCD
boundary. An electrolytic reactive barrier (e-
barrier) subsequently was demonstrated at
AOI 3B under the federal Environmental
Security Technology Certification Program
(ESTCP) to determine the technology's
efficacy in addressing remaining RDX and
2,4-DNT in source area groundwater.
[For more information, see the September
2007 issue of TNT.]
Demonstration of the e-barrier concluded
earlier this year. Samples collected after
three years of operation indicated little
reduction of RDX, TNT, and 2,4-DNT
concentrations exiting the barrier and
continued offsite migration of energetic
compounds. Results suggested that e-barrier
performance was limited due to wider
distribution of the contaminant plume than
originally estimated and its location directly
above a thick shale aquitard. A complete
cost and performance report will be
available later this year from the ESTCP
(www.estcp.org).
Remediation of the explosives plume is
moving forward. PCD recently began
implementing full-scale corrective measures
involving enhanced in situ bioremediation
(EISB) with a groundwater infiltration and
recirculation system to stimulate microbial
degradation of contaminants in the capillary
fringe. EISB was selected based on
successful application of the technology at
similar sites and in PCD pilot studies.
Construction of the state-approved EISB
system began with installation of two
infiltration galleries within the floors of two
previously excavated adjacent areas totaling
6,100 yd2. Each gallery consists of 3,100
linear feet of 1- and 2-inch perforated PVC
pipe configured in a grid that will allow even
distribution of amended water across the
excavation area.
The EISB system includes seven injection
and four downgradient extraction wells
installed to depths of 10 to 20 feet (Figure
1). Well screens are positioned within the
bottom two-thirds of the overall aquifer
thickness. Flow rates from extraction wells
are expected to range from 3 to 10 gpm.
Extracted groundwater will be amended
with a solution of 0.5 to 2.0% sodium lactate
and then reinjected into infiltration galleries
or injection wells on a rotating schedule. In
order to maintain reducing conditions in the
aquifer, the solution will contain sufficient
sodium lactate to maintain dissolved oxygen
[continued on page 2]
July 2009
Contents
Explosives
Remediation at
Pueblo Chemical
Depot Changes
Course
page 1
Five Additional
Technologies
Evaluated After
ERH Application at
Camp Lejeune page 2
Pilot Tests Lead to
Full-Scale ISCO
Using Sodium
Permanganate in
Fractured Bedrock page 4
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-------
—I 2.4-DNT Above Groundwater
I I Cleanup Level (0.068 ug/L)
I , RDX 4 2,4-DNT Above
I Groundwater Cleanup Level
-551, RDX Above Groundwater
• Cle
O Approximate Extent of
Unsaturated Alluvium
\
Monitoring Wei
Direct Push/Monitoring Wei
Proposed Extraction Well
Proposed Injection Well
Proposed Monitoring Well
Quarterly Compliance Well B
TTtrst c.- Gallery
[continued from page 1]
content below 1.0 mg/L. Pulsed injection
will be conducted to allow flushing of
the screen with recirculated groundwater
between pulses, thereby minimizing
biological growth on the screen and
preventing associated biofouling.
The infiltration and injection
recirculation system will be housed in
a weatherproof enclosure and will
consist of an influent tank, carbon
substrate tank, pumps, sampling ports,
and instrumentation with various
fittings. The system will be built to
recirculate groundwater via the
injection pump or in a closed-loop
mode with recirculation accomplished
solely by the extraction well pump.
A nutrient solution containing carbon,
nitrogen, and phosphorous in a 100:10:1
ratio also will be injected into the
subsurface, either as part of the sodium
lactate amendment or through separate
events as warranted by groundwater
nutrient conditions. The single set of
extraction wells will maintain hydraulic
control of sodium lactate solution as
well as surface infiltration of carbon
substrate solution.
Injection currently is scheduled to begin
in July 2009 and continue for a minimum
Figure 1. Six of the seven wells used for
sodium lactate injections at the PCD are
situated directly within infiltration galleries
that recirculate amended groundwater
across the contamination hot spot.
of 36 months. Recirculation and/or
sodium lactate and nutrient addition may
be extended or shortened following
review of each quarterly monitoring
event. Lactate recirculation will be
considered complete and the system will
be shut down when regulatory site-
specific groundwater cleanup goals are
met. During the post-recirculation stage,
contaminants are expected to continue
to degrade while groundwater moves
under the regional gradient and
additionally contacts accumulated
explosives-degrading bacteria. Regulatory
closure will be achieved once
concentrations for contaminants of
concern remain below specified cleanup
levels at compliance points for three
consecutive years after the remedy is
complete. Cleanup requirements for RDX
and 2,4-DNT are 0.825 ug/L and 0.1328
ug/L, respectively, based on risk-based
groundwater cleanup levels specified by
the State.
Contributed by Chris Pulskamp, PCD
(christopher.pulskamp&us. army, mil or
719-549-4252), and Andrew Ellison, Shaw
Group (andrew. ellison&shawgrp. com
or 720-554-8167)
Five Additional Technologies Evaluated After ERH Application at Camp Lejeune
Groundwater at Site 89 of Marine
Corps Base Camp Lejeune in North
Carolina is contaminated with two dense
non-aqueous phase liquid (DNAPL)
plumes and a large dissolved plume. The
Navy took a phased approach over the
past six years to address each of these
components. In 2003, electrical
resistive heating (ERH) was evaluated
in a pilot study to treat one DNAPL
plume. In 2006, field-scale treatability
studies were conducted to evaluate four
technologies for treating the dissolved
plume. In 2008, a removal action
involving soil mixing with zero valent
iron (ZVI) and clay was undertaken to
treat the second DNAPL plume.
Collective results and an upcoming
feasibility study will be used to develop
a record of decision by 2011.
ERH application used an array of 91
electrodes to deliver three-phase
electricity in a 15,900-ft2, volatile organic
compound (VOC) contaminated source
area [see February 2006 TNT]. Six
[continued on page 3]
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[continued from page 2]
months of active subsurface heating at
100°C achieved a 97-99% reduction of
VOC concentrations in groundwater and
soil at the test area. The VOC bulk
removal rate was as high as 440 Ibs/day
during peak performance, and a total of
48,000 pounds of VOCs was removed.
At a unit cost of $ 137/yd3, ERH project
costs totaled nearly $2.1 million for the
total treatment volume of 15,311 yd3.
ERH implementation at this site involved
management of roughly 2,000,000
gallons of water from the interior of the
treatment area, which was boiled off
during the heating and collected for
treatment and disposal.
Subsequent treatability studies evaluated
performance and design criteria of four
additional technologies for addressing
dissolved-phase contaminants: enhanced
reductive dechlorination (ERD) by
injecting emulsified vegetable oil (EVO)
and sodium lactate, chemical reduction by
way of ZVI injection using pneumatic
fracturing, air sparging through a
horizontal directional drilled (HDD) well,
and a permeable reactive barrier (PRB)
with mulch as a reactive medium. Each
technology was evaluated on the basis
of contaminant reductions and radius
of influence (ROI). Study area
selection was based on site layout,
plume location, and avoidance of
interaction among the four subareas.
For example, the horizontal well was
placed in an isolated elongated plume,
and the PRB was constructed in the
downgradient portion of the plume.
Field activities began with installing 11
new monitoring wells. Baseline samples
were collected from new and existing
wells in each subarea, and groundwater
was monitored throughout the study.
Highest baseline concentrations of
predominant contaminants of concern
in the study area were 21,000 ug/L for
trichloroethene (TCE) and 14,000 ug/L
for 1,1,2,2-tetrachloroethane (PCA).
Results of the treatability studies for the
dissolved-phase plume were as follows:
> ERD through EVO/Lactate Injection:
Over one week, approximately 3,050
pounds of EVO and 3,300 pounds of
sodium lactate were injected into the
subsurface through four borings and
chased with water (Figure 2). The in-
jection depth interval was 10 to 25 ft
below ground surface (bgs). Ground-
water samples were collected from
five monitoring wells one, three, and
six months after the injection. Moni-
toring indicated a maximum 3 5-foot
ROI surrounding each ERD injection
location and an average TCE reduc-
tion from 333 to 8.7 ug/L. Analysis
of field parameters, daughter prod-
ucts, natural attenuation indicator pa-
rameters, and microorganisms also
suggested that reductive dechlorina-
tion had occurred.
> Chemical Reduction through ZVI In-
jection and Pneumatic Fracturing:
Over one week, approximately 11,600
pounds of ZVI carried by nitrogen gas
were injected into the subsurface
through six borings with the aid of
pneumatic fracturing. The injection in-
terval was 12.5 feet to 25 feet bgs.
Due to a high water table, pulsing was
conducted to avoid day lighting of nitro-
gen gas to the surface near the injection
point, which would significantly reduce
the ROI. This approach inadequately
fractured the formation and resulted
in poor ZVI distribution across the
target area. Sampling of five monitor-
ing wells one, three, and six months
after the injection showed no reduction
in contaminant concentrations.
Oxidation-reduction potential (ORP)
declined over the monitoring period,
indicating that subsurface conditions
were slowly becoming favorable for
reductive dechlorination.
Air Sparging in HDD: Air was de-
livered through a 600-foot HDD
sparge well with a 240-foot-long
screen approximately 40 feet bgs near
an existing building. The system
was activated in December 2006 and
operated continuously for approximately
six months with an air compressor
"up time" of 89%. After three months
of air sparging, pneumatic fracturing
was conducted in four borings
spaced 50 feet apart along the axis
of the horizontal well screen, at 3-foot
intervals from 12.5 to 25 feet bgs.
Monthly monitoring was conducted
at eight groundwater monitoring
wells and three soil vapor wells.
Results indicated a 60-foot ROI
from the sparge well, with little ROI
enhancement from pneumatic
[continued on page 4]
Figure 2. EVO
and sodium
lactate were
injected into the
subsurface and
chased with
water in one
treatability
study area at
Site 89.
-------
IERD via EVO Chemical Air Sparging in PRB with 1
and Lactate Reduction via ZVI* Horizontal Well Mulch 1
TCE Reduction
Estimated Radius
of Influence
Cost per Treatment
Volume
94-99%
35ft
$9.71/yd3
$0.13/gal
Nil
Nil
N/A
$95.44/gal
Average 91% (shallow)
Average 96% (deeper)
60ft
$5.25/yd3
$0.07/gal
97% in wall
N/A
N/A
$0.05/ga!
* The minimum reduction in contaminant concentrations, as well as the high cost of reactive media, resulted in no further
consideration of ZVI injections at site 89. ^^^^^^^^^^^^^^^^ ^^^^^
[continued from page 3]
fracturing. Average TCE concentra-
tions decreased from 875 to 58 ug/L.
Soil vapor concentrations increased
during active sparging, but site-spe-
cific screening criteria (based on in-
dustrial exposure) were not exceeded.
> PRB with Mulch: A one-pass continu-
ous trencher was used to construct a
210- by 2-foot trench to a depth of 25
feet, which intercepted groundwater
flowing to an onsite creek at a rate of
0.14 ft/day. Approximately 200 yd3 of
mulch from the base's recycling area
and 480 yd3 of sand were placed in the
trench to achieve a ratio of 40% mulch
as a reactive medium and 60% sand as
an aggregate. Groundwater monitoring
included sampling at 11 monitoring wells
one, three, and six months after PRB
construction. Average TCE ground-
water concentrations in the wall
decreased from 13,573 to 442 ug/L.
Study results indicated favorable
conditions for contaminant degradation
(low ORP, high total organic carbon,
and low dissolved oxygen) but
determination of PRB effectiveness
over the six-month study was limited
by slow groundwater flow.
Overall effectiveness of each technology
was evaluated during the treatability study
in terms of reducing concentrations of
chlorinated VOCs within the surficial
aquifer while balancing the technology's
cost and implementation ease (Figure 3).
Soil mixing with ZVI and clay was used
last year to treat the second DNAPL area.
In this process, ZVI reacts with
contaminants to destroy them, while the
bentonite clay promotes uniform ZVI
distribution during mixing and reduces
hydraulic conductivity and associated
contaminant migration. Source area
contamination extends to approximately 25
feet bgs and encompasses 30,000 yd3 of
soil containing an estimated 62,000
pounds of solvents. A total of 900 tons
of ZVI and 1,082 tons of bentonite were
mixed into 515 overlapping columns,
while off-gas was collected and treated
with activated carbon. Treatability tests
indicated an optimum mix of 2% ZVI and
3% clay. The first round of quarterly
monitoring indicated favorable results,
with a 99.7% reduction of total VOCs in
soil and 92% reduction of total VOCs in
groundwater; both TCE and PCA
concentrations decreased more than
99%. The unit cost for soil mixing was
Figure 3. Final evaluation of
indicated that ERD and air
the dissolved-phase plume.
approximately $94/yd3, for a total
treatment cost of $2.82 million.
The Navy anticipates moving forward
with a site-wide feasibility study (FS)
next year to focus on the dissolved
groundwater plume. The FS will
evaluate air sparging and ERD combined
with monitored natural attenuation
(MNA) and land use controls. Based on
the treatability study results, air sparging
with a horizontal well may be expanded
to treat elevated VOC concentrations
across the entire site. MNA will be relied
upon to treat portions of the site where
contaminant degradation is documented.
Contributed by David Cleland,
NAVFAC Mid-Atlantic
(david.t.cleland&navy.mil or
757-322-4851), Gena Townsend, EPA
Region 4 (townsend. gena&epa. gov or
404-562-8638), and Chris Bozzini,
CH2MHill (chris. bozzini(q)ch2m. com
or 704-544-5163)
Pilot Tests Lead to Full-Scale ISCO Using Sodium Permanganate in Fractured Bedrock
Two-phase pilot testing of in-situ chemical
oxidation (ISCO) using sodium
permanganate (NaMnO4) was conducted
in 2000-2001 at the Tenneco Automotive
site inHartwell, GA, to evaluate feasibility
phase trichloroethene (TCE) plume in a
fractured bedrock aquifer [see May 2004
TNT\. The ISCO pilot was initiated to
develop an alternate remedy for the off-
facility plume; pump and treat technology
of using ISCO to remediate a dissolved- was initially considered. Difficulties in
groundwater remediation were
compounded by offsite plume migration
through connective fractures to 52
adjacent residential and commercial
properties. Pilot test results demonstrated
[continued on page 5]
4
-------
[continued from page 4]
that ISCO could effectively remediate
chlorinated volatile organic compounds
(CVOCs), which led to full-scale ISCO
implementation in 2003. The pilot test also
highlighted the need for developing an
effective hydrogeologic conceptual
model in this type of complex geologic
regime, namely fractured bedrock.
Prior to pilot testing, TCE was present
in groundwater at concentrations
reaching 12,000 |j,g/L in an onsite well
and 330 [ig/L in an off site commercial
well in the north plume area. The site is
situated in Piedmont metamorphic and
granite rocks that have weathered into a
20- to 50-ft layer of residual soil
(saprolite) near ground surface.
Hydraulic conductivity of the saprolite
is approximately IxlO"4 cm/s. A more
permeable zone of partially weathered
rock (PWR) exists beneath the saprolite
and above unweathered bedrock, at a
typical depth of 50-60 ft bgs. Impacted
groundwater exists primarily in the PWR,
which has an average hydraulic
conductivity of IxlO'2 cm/s (30 ft/day)
and an average groundwater flow rate
of 100 ft/yr in the offsite plume area. A
bifurcated TCE plume in the unconfined
PWR aquifer extends approximately 1,800
feet west beneath the facility and nearly
1,700 feet northeast into adjacent offsite
properties (Figure 4).
The Phase I pilot test was conducted using
an existing recovery well and a single
monitoring well located approximately 30
feet from the recovery well. The initial field
injection employed one gallon of a 40%
NaMnO4 solution mixed with the monitoring
well water to produce a 2.5% solution that
was injected into the subsurface through
the well. Post-injection testing of water
quality parameters such as pH, temperature,
dissolved oxygen, and ORP indicated that
oxidation of TCE by NaMnO4 had occurred.
Direct correlations between the lowest TCE
concentration and an increased chloride
concentration (3:1 ratio) and the highest ORP
measurement provided additional evidence
of TCE oxidation.
Phase II pilot testing was conducted using
an existing offsite monitoring well screened
in the PWR and located on commercial
property with the highest offsite TCE
concentration in groundwater (330 |J,g/L).
Four additional PWR monitoring wells
were installed upgradient of the existing
i—| Area of TCE Concentration
> S ug/L. Spring 2001
Area of TCE Concentration
> 5 ug/L, Spring 2008
monitoring well at 20-ft intervals. A total
of 7,780 gallons with an average
NaMnO4 concentration of 210 mg/L was
injected into a single well during four
events in May 2001. Over the next three
months, four additional 500-gallon
injections were completed withNaMnO4
concentrations of 5,600 mg/L. Phase II
results indicated that TCE
concentrations in each of the monitoring
wells decreased significantly after the
NaMnO4 injections.
Overall pilot results indicated that no
daughter products had formed, oxidant
demand was minimal (less than 10 mg/
L), and TCE concentrations were
reduced to below the maximum
contaminant level (5 ug/L) in three of
the five wells. In addition, NaMnO4 was
highly persistent in the aquifer (more
than one year), no screen fouling was
observed, and metal mobilization did
not occur. The results of pilot-scale
ISCO prompted refinement of the site
conceptual model to include a better
understanding of fracture porosity in
the PWR.
Current full-scale ISCO implementation
has built upon lessons learned during the
two pilot tests, the most
important of which was
the need to use relatively
small injection volumes
(only a fraction of
estimated pore volume) in
order to minimize
displacement of treated
groundwater. Full-scale
operations began with the
installation of 12 new wells,
[continued on page 6]
Figure 4. Groundwater
flow from the bifurcated
TCE plume is toward Lake
Hartwell to the west and
Jail House branch to the
north of the Tenneco
Automotive Site.
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Solid Waste and
Emergency Response
(5203P)
EPA 542-N-09-004
July 2009
Issue No. 43
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]
(8 injection and 4 monitoring wells) in
the north off-facility portion of the
plume. The first series of semi-annual
injections was conducted in February
2003. Single injections ranging from 250
to 500 gallons in volume were
accomplished through gravity feed of a
2% NaMnO4 solution to the screened
zone of eight wells. Similar injection
events have been conducted semi-
annually since October 2003 and are
scheduled to continue at least through
the end of 2011. The extended treatment
duration is needed mainly because of
owner restrictions regarding the quantity
and location of injection wells on private
property in the north plume area.
Spring 2008 sampling results indicate
that the areal extent of the northeast
plume has decreased approximately
30% since full-scale ISCO began
(Figure 4). The maximum TCE
concentration has declined to 120 u,g/L,
and two of the ISCO monitoring wells
now meet the TCE target of 5 u,g/L.
Mann-Kendall statistical analysis of
TCE concentrations in five wells within
the treatment area shows a statistically-
significant decreasing trend in three
wells and no significant trend in the
other two. Reduction of TCE
concentrations within the plume also
is suggested by decreased TCE
concentrations measured in the nearby
Jail House Branch and its tributaries
(Creeks A and B, Figure 4). Continued
plume reductions beneath impacted
properties are expected to lead to
several property delistings from the
mandated remediation program as early
as 2010. ISCO project costs at Tenneco
Automotive total approximately
$525,000, to date, including $85,000
for the two-phase pilot testing, $170,000
in capital costs, and $45,000 for annual
O&M that includes periodic injections.
Development of the site conceptual model,
which included adjacent onsite and offsite
areas addressed by other remedies,
incurred an additional $ 1 million.
Contributed by Charlie Spiers, GeoSyntec
Consultants (cspiers&geosyntec. com or
678-202-9500), Jason Metzger
(jmetzger&gaepd.org), and Carrie
Williams (cw illiams&gaepd. org), State of
Georgia/Environmental Protection
Division (404-657-8600)
Contact Us
Technology News and Trends
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Contributions may be submitted to:
John Quander
Office of Superfund Remediation
and Technology Innovation
U.S. Environmental Protection Agency
Phone: 703-603-7198
quander.iohn@epa.gov
EPA is publishing this newsletter as a means of disseminating useful information regarding innovative and alternative treatment techniques and
technologies. The Agency does not endorse specific technology vendors.
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