battelle 2014 bio sparge poster - uppal
TRANSCRIPT
Design and Implementation of an Integrated Biosparging and In-Situ Air
Stripping Remedial Strategy Authors: Omer J. Uppal, Elisa Buckley, Matthew J. Ambrusch, Nadira Najib, Robert Koto, Stewart H. Abrams
Langan Engineering & Environmental Services, Inc., 619 River Drive Center 1, Elmwood Park, NJ 07407
ABSTRACT
Background: This presentation provides a case study of the design and construction of a full-scale
biosparging and in-situ air stripping remediation system that was implemented to remediate the
volatile organic compound (VOC) impacts in groundwater at a site in northern New Jersey. The
subject site was originated in 1929 as a manufacturing facility and was operated by multiple
owners and tenants until 2000. Although, the site has a number of areas of concern, the
remediation system was designed and installed to primarily target a shallow groundwater plume
containing elevated concentrations of benzene, toluene, ethylbenzene, xylenes (BTEX) and
trichloroethene.
Activities: The remediation system consists of nine biosparge wells; seven wells completed to
approximately 36 feet below ground surface (bgs) and one nested well consisting of a shallow and
a deep screen completed to approximately 26 and 36 feet bgs, respectively. Trenches were
excavated to install the below grade system manifold connecting the injection points to the
process equipment. The process equipment consists of a 10 horse-power (hp) air compressor
capable of providing an air flow rate of approximately 50 standard cubic feet per minute (scfm) at
a pressure of 70 pounds per square inch (psi). The system was innovatively designed with
flexibility to be able to operate in an air sparging/stripping mode, in the event more aggressive
mass removal is needed to treat the high contaminant concentrations in an expedited manner. The
installation of the system was further complicated by the rehabilitation of a large overhead
superhighway, requiring additional coordination with the highway construction activities.
Results: Groundwater data collected before the system was activated in June 2012 indicated a
slight decreasing trend in BTEX compound concentrations. The presence of petroleum degrading
heterotrophs in the saturated soils suggested aerobic degradation was likely responsible for the
observed decreasing concentration trends. Benzene levels near where the highest concentration
of BTEX degrading microbes was observed, decreased from approximately 70 milligrams per liter
(mg/L) to 45 mg/L between June and December 2011. Dissolved oxygen (DO) concentrations were
detected as low as 0.26 mg/L. The operation of the remediation system resulted in a substantial
increase in DO concentrations within the target plume area, increased concentrations of aerobic
bacteria, and substantially improved BTEX degradation rates. The results of the recent
groundwater sampling events, operational data of the remediation system, and the overall BTEX
concentration trends are presented in this case study.
SITE LAYOUT MAP
OPERATION, MAINTENANCE, & MONITORING
EFFECTIVENESS
INSTALLATION AND CONSTRUCTION
TARGET GROUNDWATER IMPACTS
AOC-17 Groundwater
• BTEX , TCE , various metals above NJDEP GWQS in MW-3, MW-4, MW-15, and MW-18 thru MW-21
• Presence of petroleum degrading heterotrophs
• Classification Exception Area (CEA) – metals remaining in groundwater
• Biosparge System – Enhance VOC degradation
• Installed April - June 2012
• 9 sparge points
• BSP-1 thru BSP-7 screened from 34 to 36 feet below grade
• BSP-8 screened from 24 to 26 and 34 to 36 feet below grade
• Process equipment has capacity to be an air sparge system
• 35 SCFM at 175 PSI
• Modifications to well point configuration due to major utility obstructions and bridge
construction
• System has been operating since July 2012
• Annual groundwater sampling event in surrounding monitoring wells
• Monthly site visits to ensure system is operating as designed
• Compressor - 20-25 SCFM at approximately 5 PSI
• Biosparge Points – 2-3 SCFM at approximately 5 PSI
• Adjust/Optimize, as required
0
10000
20000
30000
40000
50000
60000
70000
80000
90000
100000
6/1
/20
10
8/1
/20
10
10
/1/2
01
0
12
/1/2
01
0
2/1
/20
11
4/1
/20
11
6/1
/20
11
8/1
/20
11
10
/1/2
01
1
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/1/2
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1
2/1
/20
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4/1
/20
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6/1
/20
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8/1
/20
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/1/2
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2
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/1/2
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2
2/1
/20
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4/1
/20
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6/1
/20
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8/1
/20
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/1/2
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3
Con
cent
ratio
n (p
pb)
Sampling Year
MW-17 VOC Concentrations
Benzene
Ethylbenzene
m&p-Xylenes
o-Xylene
Toluene
Trichloroethene
Xylenes (Total)
0
10000
20000
30000
40000
50000
60000
70000
80000
90000
100000
6/1
/20
10
8/1
/20
10
10
/1/2
01
0
12
/1/2
01
0
2/1
/20
11
4/1
/20
11
6/1
/20
11
8/1
/20
11
10
/1/2
01
1
12
/1/2
01
1
2/1
/20
12
4/1
/20
12
6/1
/20
12
8/1
/20
12
10
/1/2
01
2
12
/1/2
01
2
2/1
/20
13
4/1
/20
13
6/1
/20
13
8/1
/20
13
10
/1/2
01
3
Con
cent
ratio
n (p
pb)
Sampling Year
MW-16 VOC Concentrations
Benzene
Ethylbenzene
m&p-Xylenes
o-Xylene
Toluene
Trichloroethene
Xylenes (Total)
Lithology
• Fill (i.e., sand, silt, gravel) to 4-8 ft bgs
• Glacial Till (i.e., sand, silt, clay, cobbles) to approximately 45 ft bgs (bedrock)
• Slight to moderate increase in dissolved oxygen (DO)
observed in most MW’s in the injection area
• MW-18 - .66 mg/L to 3.95 mg/L
• MW-16 - .40 mg/L to .79 mg/L
• Biosparge systems take time to have a significant
remedial effect
• Effective DO distribution
• Microbial growth
• System innovatively designed such that it can be
converted to an air sparge system, if required
• Expedited mass removal
• Stripping in addition to biological degradation
• Site is segmented into three parcels, Parcel A, Parcel B, and Parcel C
• Parcel A has 17 areas of concern (AOC), alone
• In-situ air stripping of dissolved VOCs in groundwater:
• Henry’s Law Constant
• Vapor Pressure
Air Sparging
• Contaminant’s Henry’s Law Constant Required
for Effective Stripping > 1x 10-5 atm.m3/mol
• Benzene = 5.50 X 10-3 atm.m3/mol
• PCE = 1.84 X 10-2 atm.m3/mol
• TCE = 1.03 X 10-2 atm.m3/mol
• Toluene = 6.64 x 10-3 atm.m3/mol
• The effectiveness/efficiency of air sparging
depends on:
• Achievable air flow rate
• Contaminants of Concern
• Lithology
• Effective ROI