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Carbon
Dioxide Aeration and Zero Valence Iron Remediation of High
pH and Hexavalent Chromium Groundwater at a Private Site
in Niagara Falls, New York
Charles McLeod, EA Engineering, Science, and
Technology
Mike Resh, The BOC Group
Steven Rival, EA Engineering, Science, and Technology
Daniel Hinckley, EA Engineering, Science, and Technology
HRC
Treatment of a PCE Impacted Unconsolidated Aquifer
Jonathan K. Child, Fuss
& O’Neill, Inc.
Timothy J. St. Germain,
Fuss & O’Neill, Inc.
John B. Hankins,
Fuss & O’Neill, Inc.
Ex-Situ
Treatment of Dense Non-Aqueous Phase Liquids Using Calcium
Oxide (Quick Lime)
Wm. Gordon Dean,
WRS Infrastructure & Environment, Inc.
NAPL
Containment Using In Situ Stabilization
James R. Greacen, The RETEC Group, Inc.
Edward J. Walsh, Lyme Properties,
A
Case Study of Remedial Action and Closure at a Former
Manufactured Gas Plant Site
Edward P. Van Doren, Shaw Environmental, Inc.
Dennis G. Tuttle, Shaw Environmental, Inc.
Case
Study of Remediation of a Vinyl Chloride Impacted Drinking
Water Aquifer
Gerald L. DeMers and Heidi W Yantz, GeoTrans, Inc.
Carbon
Dioxide Aeration and Zero Valence Iron Remediation of High
pH and Hexavalent Chromium Groundwater at a Private Site
in Niagara Falls, New York
Charles McLeod, Jr., P.E., EA Engineering, Science, and
Technology, 3 Washington Center, Newburgh, NY 12550, Tel:
845-565-8100
Mike Resh, The BOC Group, 575 Mountain Avenue, Murray
Hill, NJ 07974,
Tel: 908-771-1452
Steven Rival, EA Engineering, Science, and Technology, 15
Loveton Circle, Sparks, MD 2115,
Tel: 410-771-4950
Daniel Hinckley, Ph.D., EA Engineering, Science, and Technology, 15
Loveton Circle, Sparks, MD 21152, Tel: 410-771-4950
A
full-scale carbon dioxide (CO2) aeration and
zero valence iron (ZVI) treatment system will be used to
neutralize pH 12+ groundwater and reduce
hexavalent chromium (Cr+6) concentrations from
approximately 0.5 mg/L to less than 0.01 mg/L, and total
chromium to less than 0.1 mg/L.
CO2 aeration and ZVI were selected as
the final remedial technology based on the results of
the feasibility study, and the successful bench-scale
study test results. This
innovative combination was developed to address
groundwater that currently recharges into a surface water
and wetland area. The
desire was to treat the impacted water without
construction of a costly treatment system, which could
require full-time operations.
To
assess the site-specific effectiveness of CO2
aeration, and to provide necessary data for design of the
full-scale system, bench-scale testing was completed using
groundwater collected from the remedial target area.
The bench-scale tests evaluated Cr+6 and
pH against applied doses of CO2 and ZVI
solutions.
The
full-scale treatment system was designed and implemented
using the bench-scale testing results.
To evaluate the effectiveness of the full-scale
treatment system, pre- and post-samples will be collected.
The system is currently under construction and is
anticipated to be on-line the first week of September,
with operational data collected monthly for the first 3
months.
This
presentation will detail the results of the bench-scale
testing results for both unit processes and the design
elements for the full-scale treatment system, and provide
an overview of the construction and start-up testing
period of the full-scale system.
HRC
Treatment of a PCE Impacted Unconsolidated Aquifer
Jonathan K. Child,
Fuss
& O’Neill, Inc. 78 Intestate Drive, West Springfield,
MA 01035, Tel: 413-452-0445 x4414,
Email: jchild@fando.com
Timothy J. St. Germain,
Fuss & O’Neill, Inc. 146 Hartford Road, Manchester,
CT 06040,Tel: 860-646-2469 x5208,
Email: tgermain@fando.com
John B. Hankins,
Fuss & O’Neill, Inc. 146 Hartford Road, Manchester,
CT 06040, Tel: 860-646-2469 x5245, Email: jhankins@fando.com
In
one of the first projects of its kind in the State of
Connecticut, Hydrogen Release Compound (HRCÒ)
was used to enhance the natural biodegradation of a plume
of groundwater contaminated with tetrachloroethene (PCE).
The technique was particularly beneficial due to
tight soil conditions and the setting of the site inside
the security fence of a State correctional facility.
Chlorinated volatile organic compound (VOC)
contamination at the study area was identified within an
approximate 8,000 square foot area.
The potential effectiveness of HRCâ
was evaluated through a Pilot Test undertaken at the
release area in the summer of 2001.
The Pilot Test included the injection of 420 pounds
of HRCÒ
by GeoprobeÒ
within an approximate 1200 square foot area centered on
the region of maximum PCE groundwater impacts
(approximately 3,000 to 4,000 micrograms per liter).
HRCÒ was injected over an approximate 10-foot vertical
interval between a depth of 4 and 14 feet.
Groundwater monitoring results obtained during four
post-injection quarterly groundwater monitoring events
documented HRCÒ
related geochemical effects within the aquifer and a
significant decline in PCE groundwater concentrations in
the Pilot Test area. Geochemical effects within the aquifer were monitored through
field parameters and a comprehensive suite of laboratory
analyses including dissolved gases, metabolic acids, and a
variety of inorganic parameters.
Based on results of the successful Pilot Test
demonstration, full-scale HRCÒ
treatment was undertaken in the summer of 2002. Full-scale treatment included the injection of 1200 pounds of
HRCÒ
by GeoprobeÒ
over an approximate 8,000 square foot area.
Effects of full-scale treatment were evaluated
through a quarterly groundwater monitoring program
completed in the summer of 2003.
It is anticipated that a program of monitored
natural attenuation and/or groundwater compliance
monitoring will be implemented in the fall of 2003 to
document post-remediation conditions within the aquifer.
Ex-Situ
Treatment of Dense Non-Aqueous Phase Liquids Using Calcium
Oxide (Quick Lime)
Wm. Gordon Dean,
PE, WRS Infrastructure & Environment, Inc., 625 E.
Tennessee Street, Suite 100, Tallahassee, FL
32308, Tel: 850-531-9860, Fax: 850-531-9866, Email:
gdean@wrsie.com
Open excavation was selected to remove dense,
non-aqueous phase liquids (DNAPLs) identified by previous
assessment activities at the FDOT Fairbanks Disposal Pit
in Gainesville, Florida.
The DNAPLs resulted from the disposal of asphalt
testing residue and consisted primarily of trichloroethene
and 1,1,1-trichloroethane.
Presumptive and visual evidence of DNAPLs had been
found in three areas of the site.
Excavation of all three areas was conducted and
DNAPLs were observed as predicted.
The original plan called for ex-situ vacuum
extraction of all contaminated soils.
All potentially contaminated soils were to be
processed through a rotary trommel, staged in 100 cubic
yard piles, and sampled for analytical testing.
Due to the increasing clay content of the deeper
soils, the trommel could not be used for most of the
potentially contaminated soils.
Quick lime was mixed into the soils at an
approximate 5% ratio to improve the soil handling
characteristics. The
combination of the heating and chemical reaction between
the soils and the lime removed the contaminants to below
the leachability soil cleanup target levels, and all
contaminated soils were ultimately treated by mixing with
quick lime. The
soils treated with quick lime were returned to the
excavation to stabilize the slopes after confirmation soil
samples verified the treatment goals had been reached.
Approximately 10,000 cubic yards of soil were
treated with quick lime, saving several million dollars as
compared to off-site disposal.
NAPL
Containment Using In Situ Stabilization
James R. Greacen, The RETEC Group, Inc., 300 Baker Avenue, Suite
302, Concord, MA 01742, Tel:
978-371-1422, Fax: 978-371-1448
Edward J. Walsh, Lyme Properties, LLC, 101 Main Street, 18th
floor, Cambridge, MA 02142, Tel:
617-225-0909, Fax: 617-225-2133
From
circa 1850 to 1960, Cambridge Gas and Light Company
operated a manufactured gas plant (MGP) in Cambridge,
Massachusetts. Since
then, the property remained undeveloped due in part to the
significant volumes of tars and oils left behind by the
former industrial operations.
Dense non-aqueous phase liquid (DNAPL) at a depth
of 20 feet below grade covered a three-acre area,
preventing site closure and inhibiting development of the
property.
To
address free DNAPL, soil and DNAPL were stabilized in
situ using a crane-mounted, 10-foot diameter auger
capable of injecting a 7% cement grout mixture.
The auger was advanced approximately 22 feet below
grade to extend beneath the DNAPL and key the stabilized
mass into the underlying clay layer. In total, 2,256 overlapping columns were advanced over an
area covering approximately 130,000 square feet.
Monitoring
was performed during stabilization operations to ensure
that performance requirements were met.
Uncured stabilized samples were collected to allow
the laboratory to place the soils into precast forms for
NAPL saturation analysis. Additional samples were collected following a curing period
to allow direct observation of stabilized material that
had cured in situ, and to provide additional
supporting documentation of the permanence of the remedy.
The
stabilization remedy allowed site closure to proceed and
allowed construction of two 300,000 square-foot life
science buildings. The construction of one building is complete and is occupied
by Vertex Pharmaceuticals.
The second building will be the world headquarters
for Genzyme Corporation, and is under construction with a
scheduled occupancy date in the fall of 2004.
Edward P. Van Doren, Shaw Environmental,
Inc., 3 Riverside Drive, Andover, MA 01810, Tel: 978-691-2130, Fax: 978-975-2065
Dennis G. Tuttle, Shaw Environmental, Inc., 3 Riverside
Drive, Andover, MA 01810 Tel:
978-691-2142, Fax: 978-975-2065
A
seemingly straightforward remediation of a former
Manufactured Gas Plant (MGP) Site in western Massachusetts
presented numerous challenges during the course of
remediation activities and final closure.
The former MGP operated
between 1889 and 1922 making gas from oil and was located
adjacent to a wetland.
The Site is also approximately 500 feet from two
municipal wellheads and surrounded by residential
dwellings. The
source of groundwater for the municipal wells is a deep
artesian aquifer with a potentiometric surface elevation
more than 30 feet above ground surface.
The artesian aquifer is overlain by a clay aquitard
over 100 feet thick to less than 20 feet at the Site.
Site contamination consisted primarily of
Polynuclear Aromatic Hydrocarbons (PAHs) and Volatile
Organic Hydrocarbons (VOCs) located within soils above the
confining clay layer.
Contaminated soil depths ranged from 20 feet below
ground surface (bgs) at the former MGP parcel to 2 feet
bgs in wetland soils.
The initial remediation called for the excavation
of approximately 26,000 square feet (SF) of wetland and
8,500 SF of buffer zone soils while minimizing excavation
into the clay. The
soils were treated by thermal desorption and off site
disposal and the wetland and buffer zone were restored.
As the remediation work progressed it became
apparent from confirmatory sampling that additional
excavation in the wetland and buffer zone was required and
that compete removal of contaminated soils was not
feasible. Groundwater
remediation was achieved by a combination of source area
removal and natural attenuation as part of a Monitored
Natural Attenuation (MNA) plan.
Site closure maximized the risk reduction and
resulted in: a condition of No Significant Risk under
current conditions for a residential exposure scenario;
maintaining the integrity of the clay aquitard protecting
the municipal wells; and minimizing restrictions placed in
an Activity and Use Limitation (AUL).
Case
Study of Remediation of a Vinyl Chloride Impacted Drinking
Water Aquifer
Gerald L. DeMers
and Heidi W Yantz, GeoTrans, Inc., 175 North Corporate Drive, Brookfield, WI 53045 Tel:
262-792-1282, Fax: 262-792-1310
In
1994, a Remedial Investigation (RI) and Feasibility Study
(FS) were completed for a NPL landfill in Ripon,
Wisconsin. The
Record of Decision (ROD) required the construction of a
composite landfill cap and passive gas collection system;
this work was completed in 1996. The
ROD did not require the active remediation of groundwater.
During
routine groundwater monitoring in the fall of 2001, vinyl
chloride was detected in one private drinking well located
in the sandstone aquifer and down gradient of the site.
Additional monitoring of a new home indicated that
its well was also impacted. Following these detections, the PRP group provided bottled
water to the residents and installed air strippers and
activated carbon treatment units as interim measures at
the homes. An
extensive groundwater monitoring investigation was
performed to fully define the vertical and horizontal
extent of groundwater impacts and to characterize the
hydrogeology of the sandstone aquifer at the site. In
addition, the public water supply was extended to the two
impacted homes to provide a permanent remedy. The site was
also evaluated for natural attenuation of chlorinated
solvents at the landfill, and of the vinyl chloride plume.
A reducing environment exists beneath the landfill,
and TCE and DCE are reductively dehalogenated to vinyl
chloride near the site.
Further monitoring and fate and transport modeling
are required to show that the vinyl chloride is being
attenuated.
A
Focused FS is being prepared to evaluate alternatives to
remediate the vinyl chloride plume.
Alternatives considered include natural
attenuation, extending water supply to additional
residences, pump and treat, circulation wells,
bioaugmentation and active gas extraction at the landfill.
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