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Cost and Performance
Report:
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Preparation of this report has been funded wholly or in part by the U.S. Environmental Protection Agency under Contract Number 68-W3-0001. It has been subject to administrative review by EPA headquarters and Regional staff and by the technology vendor. Mention of trade names for commercial products does not constitute endorsement or recommendation for use.
This report presents cost and performance data for a soil vapor extraction (SVE) application at the Verona Well Field Superfund site in Battle Creek, Michigan.
This site was the primary well field for potable water for the city of Battle Creek. In 1984, the wells were determined to be contaminated with chlorinated solvents, and several source areas, including the Thomas Solvent Raymond Road (TSRR) area were identified. TSRR was used from the 1960s to the 1980s for storage and packaging of solvents. Spills from these operations, along with leaks from underground storage tanks, resulted in soil and groundwater contamination in this area. The contaminants of concern were volatile organic compounds (VOCs), primarily tetrachloroethene (PCE) and 1,1,1-trichloroethane.
A Record of Decision (ROD), signed in 1985, identified soil vapor extraction (SVE) as the remedial alternative for the TSRR area. Cleanup standards for the area were established in a 1991 ROD. The SVE system included 23 extraction wells, a separator, and offgas treatment. Both carbon adsorption and catalytic oxidation were used with this system, with catalytic oxidation used when the contaminant removal rate was greater than 10 lbs/day. A pilot-scale SVE system was operated in October 1987. Full-scale operation began in March 1988 and continued through May 1992.
The full-scale SVE system removed an estimated 45,000 pounds of VOCs. The soil cleanup standards were achieved for all VOCs with the exception of PCE. While there were several exceedances of the PCE standard, the average concentration of PCE was reported to be below the cleanup standards.
A groundwater pump and treat system was used at the TSRR area from March 1987 to December 1991. The system included nine shallow extraction wells and an air stripper. In addition, a pilot-scale groundwater sparging study was conducted in July 1991 and a sparging test was performed from December 1991 to April 1992.
Approximately $2,180,000 were expended for the SVE application at Verona, including $1,645,281 for activities directly associated with treatment. The $1,645,281 value corresponds to $62/cubic yard of soil treated (estimated as 26,700 cubic yards of soil) and $37/pound of VOC removed. Costs for this application were increased because of the requirement for extensive sampling and analysis. No information is contained in the available references on costs for groundwater cleanup at Verona.
Table of Contents | Forward to Site Information
Verona Well Field
Battle Creek, Michigan
Thomas Solvent Raymond Road
(Operable Unit #1)
CERCLIS #: MID980793806
ROD Dates: 12 August 1985; 28 June 1991
Type of Action: Remedial
Treatability Study Associated with Application? No
EPA SITE Program Test Associated with Application? No
Operating Period: March 1988 to May 1992
Quantity of Soil Treated During Application:26,700 cubic yards of soil
(Based on an estimate provided by the vendor of a capture zone of 36,000
ft2 and a depth of contamination of 20 ft.)
Historical Activity That Generated Contamination at the Site: Solvent
storage, blending, repackaging, distribution, and disposal
Corresponding SIC Code: 7389 (Business Services, not elsewhere
classified)
Waste Management Practices That Contributed to Contamination: Spill:
underground storage tanks
Site History:
The Verona Well Field site was the primary well field of
potable water for the city of Battle Creek, Michigan, as shown in Figure 1.
Routine testing in August 1981 of the water supplies indicated that 10 of the
city’s 30 wells contained detectable levels of volatile organic compounds.
By early 1984, 27 of the 30 supply wells were determined to be contaminated
with volatile organic compounds (VOCs). As shown in Figure 2, three areas
were identified as the sources of the contamination: the Thomas Solvent Raymond
Road (TSRR) area, the Thomas Solvent Annex (TSA), and the Grand Trunk Western
Railroad (GTWRR) facility. The TSRR area was used by the Thomas Solvent Company
for solvent storage, transfer, and packaging from 1963 to 1984. This area,
shown in Figure 3, was found to have the largest mass of contamination among
the three source areas. Underground storage tank leakage and surface spills
resulted in contamination of the soil and groundwater at the site. [11]
Figure 1. Site Location
Figure 2. Vicinity Map [11]
Figure 3. Thomas Solvent Raymond Road [10]
In May 1984, an Initial Remedial Measure was implemented that included converting 12 production wells into blocking wells to control the migration of the plume, installing three new production wells in the well field, and installing an air stripping system to treat extracted contaminated groundwater. [1, 10]
Regulatory Context: In August 1985, a ROD was signed for the TSRR Operable Unit #1 (OU-1) to remediate the soil by soil vapor extraction and the groundwater by pumping to the existing air stripper for treatment. A second ROD was signed in June 1991 to remediate the TSA and GTWRR source areas through soil vapor extraction and groundwater extraction and treatment with air stripping, and continued extraction and treatment of the groundwater at the TSRR source area. The second ROD also established final cleanup goals for the source areas, including the TSRR. [1, 10]
Remedy Selection: Soil vapor extraction (SVE) was
selected as the remedial alternative for the TSRR source area. SVE was expected
to remediate the contamination to 2% of its original mass (initially estimated
as 1,700 lbs) within 2 years of operation. In addition, the installation and
operation of SVE would not disturb the soil and cause volatilization of the
contaminants to the surrounding area. Other alternatives (capping, soil
flushing) were determined to be inconsistent with anticipated future activities
at the site or were believed to require too much time to remediate the soil.
[1, 12]
Site Management: Fund Lead
Oversight: EPA
Remedial Project Manager:
Margaret Guerriero/George Hudak
U.S. EPA - Region 5
77 W. Jackson Blvd.
Chicago, IL 60604
(312) 886-0399/(312) 886-6144
Prime Contractor:
Paul Boersma
CH2M Hill
411 E. Wisconsin Avenue
Milwaukee, WI 53202
(414) 272-2426
Treatment System Vendor:
Robert Piniewski
Terra-Vac
9030 Secor Road
Temperance, MI 48182
(313) 847-4444
Back to Executive Summary |
Table of Contents | Forward to Matrix Description
Type of Matrix Processed Through the Treatment System: Soil (in situ); Groundwater
Primary Contaminant Group: Halogenated and nonhalogenated volatile solvents.
The primary contaminants identified in the soil and groundwater included tetrachloroethene (PCE), trichloroethene, 1,1,1-trichloroethane, acetone and toluene. A light nonaqueous phase liquid (LNAPL) layer was identified in the groundwater. The contamination in the unsaturated zone covered an area of approximately one acre and the groundwater plume in the saturated zone covered an area of approximately one mile by one-half mile at the site. [1]
Data from the remedial investigation, conducted in November 1983, indicated that the total estimated volume of organic compounds, at the TSRR source area in the groundwater to be 3,900 pounds, and in the soil to be 1,700 pounds. These mass estimates were based on sample data obtained using a soil sampling procedure that is now known to produce VOC results lower than actual values. The total VOC mass in groundwater and soils was estimated in 1988 to be 13,000 to 16,500 pounds. This estimate was based on a pre-construction investigation performed prior to the installation of the SVE system. A special sampling technique, involving the use of 3-inch brass liners fitted inside the split spoon sampler, was employed for this soil sampling event to minimize handling and volatilization of the samples. [1, 12]
The major matrix characteristics affecting cost or performance for this technology and their measured values are presented in Table 1. A particle size distribution as determined by the Unified Soil Classification System for soil boring W-6 at a depth of 10 feet is shown in Table 2.
Table 1. Matrix Characteristics [5, 10, 17]
| Parameter | Value | Measurement Method |
|---|---|---|
| Clay Content | <5% | USCS |
| Particle Size Distribution | See Table 2 | USCS |
| Moisture Content | 5% | estimated |
| Air Permeability | 10 cm/sec | estimated |
| Porosity | 30-40% | estimated |
| Total Organic Carbon | Not available | -- |
| Nonaqueous Phase Liquids | Present (LNAPL layer identified) | -- |
| Hydraulic Conductivity | 0.0025 cm/sec | Not available |
Table 2: Particle Size Distribution [5]
| Soil Type | % |
|---|---|
| Gravel | 5.70% |
| Coarse Sand | 4.00% |
| Medium Sand | 21.50% |
| Fine Sand | 64.20% |
| Silt and Clay | 4.60% |
Site Geology/Stratigraphy
The geology at the site consists of 10 to 50
feet of relatively permeable Pleistocene and recent glacial and alluvial sand,
sometimes gravelly or silty. These deposits overlie the Mississippian-age
Marshall Sandstone, primarily a fine- to medium-grained quartz sandstone with
interbeds of limestone, siltstone, and shale, particularly at depths of 90 to
100 feet. The sandstone is 100 to 120 feet thick and overlies the Mississippi
Coldwater Shale, a gray to dark gray and silty shale. The shale thickness at
the site is unknown as rock cores did not fully penetrate the shale. The
natural groundwater surface at the site is located between 14 and 16 feet;
however, pumping of the extraction wells lowers the water table to between 16
and 25 feet. The groundwater extraction system used in this application created
a 50-foot cone of influence in the glacial aquifer. Bedrock beneath the site
occurs on the average of 35 feet below the water table. Figure 4 shows the
location of geologic cross-sections for the TSRR source area; Figures 5 and 6
show the results from characterizing the geology of the TSRR source area.
[10, 13]
Figure 4. Geologic Cross-Section Locations [13]
Figure 5. Geologic Cross-Section C-C'
[13]
Figure 6. Geologic Cross-Section D-D'
[13]
Back to Site Information | Table of Contents | Forward to Treatment System Description
Soil Vapor Extraction
Pump and Treat With Air Stripping
Sparging
Post-treatment (Air)—Carbon Adsorption and Catalytic Oxidation
A description of the soil vapor extraction system (both pilot-scale and full-scale) and the groundwater extraction system is presented in this section.
Soil Vapor Extraction—Pilot-Scale: A pilot-scale SVE system was installed in November 1987 and was operated intermittently over 15 days for a total operation time of 69 hours. The system consisted of 4 wells with individual extracted air flow rates ranging from 60 to 165 standard cubic feet per minute (scfm), and wellhead vacuums of 3 to 4 inches of mercury. The extraction wells were first operated independently to determine their radius of influence and their vapor flow rate/vacuum pressure relationship, to investigate the effect of the underground tanks on the vacuum pressure distribution in the vadose zone, and to identify the VOC loading rates from the individual wells as a function of vacuum pressure and flow rate. The results were used to determine the optimum process variables and locations of additional wells for the full-scale system.
The total VOC concentrations in the soil vapor ranged from 2 mg/L to 204 mg/L with approximately 3,000 pounds of contaminants being removed. The radius of influence for the wells was determined to be greater than 50 feet, as measured with vacuum piezometers in nearby extraction wells. The average stack gas concentration of VOCs was 0.067 mg/L, at an average combined flow rate of 500 cfm.
Soil Vapor Extraction—Full-Scale: The full-scale soil vapor extraction (SVE) system used at the Verona Well Field TSRR, shown in Figure 7, consisted of 23 extraction wells, an air/water separator, offgas treatment, and two vacuum blowers. The extraction wells were 2- and 4-inch diameter polyvinyl chloride (PVC) screened from approximately 5 feet below the ground surface to 3 feet below the groundwater table. The extraction wells had a sand pack around the screen portion and were also grouted to grade to prevent short circuiting of soil vapor along the side of the extraction wells. The extraction wells were connected together by a surface collection manifold. A throttling valve, sample port, and vacuum pressure gauge were attached to each well. The surface manifold was connected to a centrifugal air/water separator followed by vapor-phase carbon air treatment and 40- and 25-horsepower vacuum units. Following treatment, the off gas was discharged to the atmosphere through a 30-foot stack [9, 11].
Figure 7. Schematic of Soil Vapor Extraction System [10]
During this full-scale operation, 14 of the 23 wells were used at a time to maximize the contaminant loading to the off-gas system. The selection of the 14 wells was determined based on VOC concentrations at the wellhead. This operating scheme produced a combined system air extraction flow rate between 1,400 and 1,600 scfm.
The SVE system was operated from March 1988 to May 1992. Operation of the system was temporarily suspended from November 1990 to February 1991, to dismantle the system, to remove the underground tanks, and to re-install the full-scale SVE system.
According to the vendor, the underground storage tanks were left in place due to health and safety concerns until the level of contamination was reduced. The tanks were removed in January 1991 after the SVE system had removed over 40,000 pounds of contaminants.
In February 1991, the SVE unit resumed operation and consisted of 20 wells, including 10 existing and eight new vapor extraction wells, and two new, dual groundwater/SVE wells, as shown in Figure 8. This re-assembled system operated almost continuously from February 1991 to May 1992 and produced a combined system air extraction flow rate of 1,000 scfm.
Figure 8. SVE System Layout
Carbon Adsorption—When the SVE system was originally installed, carbon adsorption was used to remove volatile organic compounds (VOCs) from the vapor stream prior to discharge. The carbon adsorption system, which was used from March 1988 to January 1990 and again from February 1991 to May 1992, consisted of two sets of four carbon vessels connected in series. Each carbon vessel contained 1,000 lbs of granular activated carbon. The primary set of carbon vessels adsorbed the majority of the VOCs; the secondary set was a backup for contaminant breakthrough from the primary set. The primary carbon was sent off site for regeneration and the secondary carbon placed in the primary position when breakthrough occurred. Carbon adsorption was selected because the contaminant mass was expected to be relatively small; however, full-scale SVE operation indicated that the total VOC mass in the subsurface was approximately 25 times larger than originally estimated, and carbon changeouts were required more frequently than originally anticipated. These changeouts resulted in greater downtime of the extraction system than anticipated, and the carbon system was replaced with a catalytic oxidation (CATOX) unit. Based on the relatively lower mass of VOCs remaining in the subsurface in February 1991 as compared with January 1990 (following the removal of the USTs and surrounding contaminated soil), carbon adsorption was determined to be more cost effective than the CATOX unit to treat the SVE off gas and was re-installed at this time. [9, 11]
CATOX—The CATOX system, which was used from January 1990 to October 1990, consisted of a particulate filter, blower, heat exchanger, a natural gas-fired burner, and catalyst bed. Chlorinated compounds that entered the CATOX unit were converted to carbon dioxide, water vapor, and hydrochloric acid. The catalyst in the system enabled the oxidation reaction to occur at lower temperatures than would be possible without the catalyst. During its use at the site, the CATOX system was run at temperatures between 780°F and 820°F. [9, 11]
Groundwater Extraction System: In addition to the SVE
system, a groundwater pump and treat system was used at the TSRR from March
1987 to December 1991. The groundwater extraction (GWE) system, as shown in
Figure 9, consisted of nine shallow extraction wells, screened in the
unconsolidated aquifer, their associated instrumentation and controls, and
approximately 5,000 feet of double-walled HDPE (high-density polyethylene)
extraction force main piping. The well depths, screened intervals, and typical
pumping rates for the wells are presented in Table 3. All but Extraction Well
(EW) 8 are 8-inch diameter wells. EW-8 is a 24-inch diameter well that was
installed in the vicinity of the LNAPL layer and operates as a dual
groundwater/product recovery well. Groundwater was extracted from the
individual wells to the monitoring building, and fed to the extraction force
main (common header), which carries the groundwater to the wet well at an
existing air stripper in the well field. The extraction wells each discharged
between 30 to 70 gallons per minute (gpm) of groundwater for a total combined
flow of 300 to 350 gpm. The capture zone of the GWE system is shown in Figure
10.
Figure 9. Groundwater Extraction System Layout [10]
Table 3. Verona Well Field (TSRR) Groundwater Extraction Well Characteristics [11]
| Extraction Well (EW) | Well Diameter (inches) | Well Depth (feet) | Screen Interval (feet) | Typical Pumping Rate (gpm) |
|---|---|---|---|---|
| 1 | 8 | 33 | 13 to 30 | NA* |
| 2 | 8 | 40 | 20.5 to 37 | 57 |
| 3 | 8 | 40 | 20.5 to 37 | 59 |
| 4 | 8 | 40 | 20.5 to 37 | 37 |
| 5 | 8 | 40.5 | 20.5 to 37.5 | 34 |
| 6 | 8 | 40 | 20 to 37 | 38 |
| 7 | 8 | 40 | 20 to 37 | 24 |
| 8** | 24 | 43 | 12 to 36 | 50 |
| 9 | 8 | 40 | 20.5 to 37 | 60 |
*EW-1 was abandoned in 1989.
**EW-8 is a product recovery well with a 24-inch steel casing. An 8-inch
groundwater extraction well is also located within the well.
Figure 10. Approximate Groundwater Extraction Well Capture Zone in
Unconsolidated Unit, April 1989 [11]
The GWE system was completed and began operating in March 1987. Through 1988, the product recovery pump in EW-8 removed more than 150 gallons (approximately 1,200 pounds) of the NAPL, which was collected in a holding tank and ultimately disposed off site. EW-1 was removed from service in 1989 because the maximum extraction rate was only 5 to 7 gpm. In 1990, EW-8 was converted to a dual vacuum extraction (DVE) well. The use of the DVE resulted in a 30% increase in vapor phase VOC recovery rates of the SVE system. The use of DVE was limited to the capacity of the existing groundwater treatment system, and consequently, additional DVE extraction wells could not be included because the treatment system could not accommodate the quantity of water that would be generated.
Sparging—In July 1991, a pilot-scale groundwater sparging (GWS) study was conducted using three sparging wells to evaluate sparging as a potential means for improving the performance of the GWE system for remediating the saturated soils. The sparging wells (AW1, AW2, and AW3) were installed at a depth between 30 to 35 feet below ground surface (approximately 10 feet below the dynamic water table) and were constructed of 2-inch PVC pipe with a 2-foot screen. The sparging wells were placed in an arc around EW-8 and were within the zone of influence for both groundwater and vacuum extraction. Each well included a rotameter to measure flow rates, and a pressure gauge to measure injection pressures. Additionally, two piezometer nests were installed to assess the effects of sparging within EW-8. Each nest consisted of a shallow (8 feet above the saturated zone), medium (3 feet above the saturated zone), and deep (2 feet below the dynamic water table) piezometers, constructed of 2-inch PVC pipe with a 2-foot screen. Nitrogen was used as the sparging gas instead of air to minimize formation of iron oxides in the groundwater. Based on the results of the pilot-scale study, a five-month sparging study was conducted from December 1991 to April 1992. [4, 11]
The major operating parameters affecting cost or performance for this technology and the values measured for each are presented in Table 4.
Table 4. Operating Parameters [9]
| Parameter | Value | Measurement Method |
|---|---|---|
| Air Flow Rate | 1,400 to 1,600 cfm | Not specified |
| Operating Pressure/Vacuum | Not available | -- |
A timeline for this application is shown in Table 5.
Table 5. Timeline [1, 2, 10, 11, 12, 13, 16]
| Start Date | End Date | Activity |
|---|---|---|
| September 1983 | -- | Verona Well Field added to the National Priorities List |
| May 1984 | -- | Initial Remedial Measure implemented |
| August 1985 | -- | ROD signed for Operable Unit #1 |
| March 1987 | December 1991 | Operation of GWE System |
| October 1987 | -- | Pilot-scale operation of SVE |
| March 1988 | May 1992 | Full-scale operation of SVE |
| January 1990 | October 1990 | Catalytic oxidation unit used in SVE system in place of carbon adsorption |
| November 1990 | February 1991 | SVE operation temporarily suspended |
| January 1991 | -- | Underground storage tanks removed |
| February 1991 | May 1992 | SVE operation resumes; carbon adsorption replaces CATOX unit |
| June 1991 | June 1991 | Pilot-Scale Sparging Test |
| June 1991 | -- | Second ROD Signed |
| December 1991 | April 1992 | Sparging Test |
| June 1992 | -- | Performance Objective Soil Sampling |
Back to Matrix Description | Table of Contents | Forward to Treatment System Performance
The 1991 ROD specified the cleanup standards, shown in Table 6 for soil and groundwater at Verona. The 1991 ROD, which addressed and specified the remedy for the TSRR and two other source areas, stated that final soil and groundwater cleanup standards for the TSRR source area were to be the same as those for the TSA and GTWRR source areas. [10] The tetrachloroethene (PCE) cleanup goal shown in Table 6 (0.014 mg/kg, or 14 ppb) was changed from the goal shown in the 1991 ROD (10 ppb) to be consistent with a State of Michigan law (Act 307), which became effective subsequent to the signing of the 1991 ROD. Act 307 established levels for contaminants in soil that correspond to a 10-6 risk level.
Table 6. Cleanup Standards [10]
| Constitutent | Soil Cleanup Standards (mg/kg) | Groundwater Cleanup Standards (mg/L) |
|---|---|---|
| Acetone | N/A | 0.7 |
| Benzene | 0.02 | 0.001 |
| Carbon Tetrachloride | 0.01 | N/A |
| Chlorobenzene | N/A | 0.1 |
| Chloroform | N/A | 0.006 |
| 1,1-Dichloroethane | 0.02 | 0.001 |
| 1,1-Dichloroethene | 0.01 | 0.001 |
| 1,2-Dichloroethane | 0.01 | 0.001 |
| cis-1,2-Dichloroethene | 0.02 | 0.001 |
| trans-1,2-Dichloroethene | 2 | 0.1 |
| Ethylbenzene | 1.4 | 0.07 |
| Methylene chloride | 0.1 | 0.005 |
| Tetrachloroethene | 0.014 | 0.001 |
| Tolune | 16 | 0.8 |
| 1,1,1-Trichloroethane | 4 | 0.2 |
| 1,1,2-Trichloroethane | N/A | 0.001 |
| Trichloroethene | 0.06 | 0.003 |
| Vinyl chloride | N/A | 0.001 |
| Xylenes | 6 | 0.3 |
N/A - Cleanup standards not specified for this constituent in this media.
Although the 1985 ROD did not specify chemical-specific cleanup goals, contractual documents for the construction, operation, and maintenance of the SVE system, developed following the 1985 ROD, initially specified two performance objectives (1) none of the treated soil samples could have VOC concentrations greater than 10 mg/kg; and (2) less than 15% of the soil samples could have VOC concentrations greater than 1 mg/kg.
As specified in the 1991 ROD (signed during the operational phase for the SVE system), constituent-specific cleanup standards for soil and groundwater were established that superseded the performance objectives stated in the contractual documents.
Soil Vapor Extraction System
Table 7 presents the analytical results of the performance objective soil sampling effort at the TSRR area. Confirmatory sampling of 26 soil borings was conducted in June 1992 to determine if the SVE system achieved the soil cleanup standards. A total of 115 soil samples were collected at random horizontal and vertical directions within each grid of the grid system established in accordance with the MDNR Guidelines for Verification of Soil Remediation. The soil samples were analyzed for VOCs according to CLP custody and analysis protocols.
Table 7. Analytical Results of Soil Sampling at the TSRR Source [2, 3, 10]
| Constitutent | Soil Cleanup Standard (mg/kg) | Untreated Soil (mg/kg) (Maximum) | Treated Soil (mg/kg) (Range) | Number of Detects | Number of Detects Greater than Cleanup Standard |
|---|---|---|---|---|---|
| Acetone | 14 | 130 | ND to 0.18 | 13 | 0 |
| Benzene | 0.02 | NA | ND to 0.001 | 24 | 0 |
| 2-Butanone | 8 | 17 | ND to 0.018 | 3 | 0 |
| Carbon Disulfide | 14 | NA | ND to 0.002 | 4 | 0 |
| Carbon Tetrachloride | 0.01 | NA | ND | 0 | 0 |
| Chloroform | 0.12 | 2 | ND to 0.007 | 8 | 0 |
| Chloromethane | 0.06 | NA | 0.007 | 1 | 0 |
| 1,1-Dichloroethane | 0.02 | NA | ND | 0 | 0 |
| 1,2-Dichloroethane | 0.01 | 27 | ND to 0.005 | 4 | 0 |
| 1,1-Dichloroethene | 0.01 | NA | ND | 0 | 0 |
| 1,2-Dichloroethene (total) | 2 | NA | ND to 0.006 | 14 | 0 |
| cis-1,3-Dichloropropene | 0.004 | NA | 0.002 | 1 | 0 |
| Ehtylbenzene | 1.4 | 78 | ND to 0.004 | 4 | 0 |
| Methylene chloride | 0.1 | 60 | 0.002 | 1 | 0 |
| Tetrachloroethene | 0.014 | 1800 | ND to 0.711 | 70 | 20 |
| Toluene | 16 | 730 | ND to 0.073 | 16 | 0 |
| 1,1,1-Trichloroethane | 4 | 270 | ND to 0.004 | 18 | 0 |
| Trichloroethene | 0.06 | 550 | ND to 0.047 | 38 | 0 |
| Xylenes (total) | 6 | 420 | ND to 0.018 | 4 | 0 |
ND - Not Detected
The mass of volatile organic compounds (VOCs) removed during this SVE application is shown in Figure 11 as a function of cumulative days of system operation.
Figure 11. Total VOCs Removed Through Soil Vapor Extraction [11]
An in-line photoionization detection meter was used to monitor and determine breakthrough of the primary carbon system effluent. An on-site gas chromatograph was utilized to analyze vapor samples from individual wellheads and from the carbon system to calculate VOC loading and breakthrough rates.
Groundwater Pump and Treat System
Dissolved phase VOC concentration data were collected to assess the performance of the nitrogen sparging system. Groundwater sample analyses were performed using EPA Methods 601, 602, 8010, and 8020. Table 8 presents dissolved phase VOC data for selected constituents from EW-8 for groundwater monitoring events both before and during sparging and for two events after sparging. Figure 12 shows the measured concentrations in the extracted vapor (i.e., vapor phase VOC concentrations) from EW-8 before sparging (June, September, and November 1991) and during sparging (December 1991 through April 1992).
Table 8. Summary of Dissolved Phase VOC Concentrations (µg/L) at EW-8 [4]
| VOC | 3/91 | 5/91 | 7/91 | 9/91 | 11/91 | 12/91 | 2/92 | 2/92 | 3/92 | 4/92 | 6/92 | 7/92 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1,2-Dichloroethene (total) | 170 | 140 | 300 | 290 | 360 | 370 | 140 | 71 | 130 | 0 | 530 | 90 |
| Tetrachloroethylene | 440 | 430 | 480 | 510 | 310 | 380 | 220 | 160 | 84 | 30 | 250 | 87 |
| 1,1,1-Trichloroethane | 100 | 96 | 220 | 140 | 100 | 120 | 0 | 10 | 33 | 10 | 90 | 30 |
| Trichloroethylene | 290 | 270 | 480 | 350 | 300 | 320 | 84 | 73 | 160 | 60 | 400 | 120 |
| Toluene | 320 | 250 | 20 | 370 | 99 | 580 | 130 | 39 | 48 | 0 | 380 | 130 |
| Xylenes (total) | 230 | 280 | 430 | 330 | 97 | 390 | 180 | 160 | 19 | 0 | 0 | 75 |
| Ethylbenzenes | 14 | 0 | 0 | 41 | 0 | 68 | 22 | 0 | 0 | 0 | 0 | 7 |
| Total VOCs | 1,564 | 1,466 | 1,930 | 2,031 | 1,266 | 2,228 | 776 | 513 | 474 | 100 | 1,650 | 539 |
NOTE: Sparging started on December 3, 1991, and ended on April 30, 1992.
Figure 12. Vapor Phase VOC Concentrations in EW-8 vs. Time. [4]
The analytical results from the soil sampling in June 1992 shown in Table 7 indicate that the SVE system achieved the cleanup standards for all VOCs with the exception of PCE. PCE was detected at concentrations greater than the cleanup standard of 0.014 mg/kg in 20 of 115 soil samples. According to the prime contractor, the average PCE concentration in the soil samples was less than the 0.014 mg/kg cleanup standard. [19]
Figure 11 indicates that over the course of about 375 days of operation, 45,000 lbs of total VOCs were removed through operation of the SVE system. Total VOCs shown in Figure 11 are the sum of the concentrations for the 19 constituents shown in Table 7. In addition, Figure 11 shows that the VOC removal rate had dropped from a high of 1,000 lbs/day during the first 2 weeks of operation to less than 100 lbs/day after 250 days of operation. According to the vendor, the removal rate had dropped to less than 1 lb/day after 400 days of operation. [17]
According to the remediation contractor, data from the groundwater remediation indicates the following:
The results for vapor phase VOC concentrations (Figure 12) indicate that the VOC concentrations increased from about 0.04 mg/L to 0.342 mg/L during the first two months of sparging, then decreased to the pre-sparging levels of about 0.05 mg/L in March.
The available data are suitable for matching the maximum untreated soil concentrations to a range of treated soil concentrations.
CLP protocols used for laboratory analysis of soil boring samples include required QA/QC procedures. The results for the QA/QC efforts are available from the contractor or vendor for this application. [3]
Back to Treatment System Description | Table of Contents | Forward to Treatment System Cost
The remedial activities at the Verona Well Field Site were funded by EPA. Procurement of soil vapor extraction began in March of 1987 and ended seven months later in September 1987. CH2M Hill was the prime contractor who subcontracted with Terra Vac for the vacuum extraction technology, in a competitive procurement process. [20]
In September of 1990, the contract was switched from a Remedial Planning (REM) IV contract to an Alternative Remedial Contracting Strategy (ARCS) contract. Since there are different requirements under ARCS, CH2M Hill rebid the subcontract. When the subcontract was rebid under ARCS, CH2M Hill wrote a sole source justification for Terra Vac to continue the work. [20]
Tables 9 and 10 present the costs for the Soil Vapor Extraction application at Verona Well Field. In order to standardize reporting of costs across projects, costs are shown in Tables 9 and 10 according to the format for an interagency Work Breakdown Structure (WBS). The WBS specifies 9 before-treatment cost elements, 5 after-treatment cost elements, and 12 cost elements that provide a detailed breakdown of costs directly associated with treatment. Tables 9 and 10 present the cost elements exactly as they appear in the WBS, along with the specific activities, and unit cost and number of units of the activity (where appropriate), as provided by the treatment vendor (Terra Vac) and oversight contractor (CH2M Hill). CH2M Hill provided costs for contractor oversight and soil sampling and analysis. All other costs were provided by Terra Vac.
Table 9. Actual Costs for Activities
Directly Associated with Treatment
[Adapted from 17, 19]
| Activity | Unit Cost | Number of Units | Cost |
|---|---|---|---|
| Vapor/Gas Preparation and Handling | |||
| Activiated carbon (per lb.) | $2.55 | 14,600 | $37,230.00 |
| Catalytic oxidation (per 2 months) | $18,720.00 | 0.22 | $4,118.40 |
| 80,000 pounds of carbon | $170,000.00 | lump sum | $170,000.00 |
| 100,000 pounds of carbon plus additional labor | $285,000.00 | lump sum | $285,000.00 |
| CATOX continuous operation | $78,000.00 | lump sum | $78,000.00 |
| Carbon Adsorption System | $4,650.00 | lump sum | $4,650.00 |
| Mobilization/ Setup | |||
| Submit O&M Manual | $25,000.00 | lump sum | $25,000.00 |
| Submittals - Pilot Test | $27,000.00 | lump sum | $27,000.00 |
| Set-up Facilities | $49,000.00 | lump sum | $49,000.00 |
| Evaluate Well Data | $4,000.00 | lump sum | $4,000.00 |
| Pilot Test Design | $15,000.00 | lump sum | $15,000.00 |
| Install Pilot test | $43,000.00 | lump sum | $43,000.00 |
| SVE Design/Submittals | $29,000.00 | lump sum | $29,000.00 |
| Install Manifold | $11,000.00 | lump sum | $11,000.00 |
| Install Vacuum System | $115,000.00 | lump sum | $115,000.00 |
| Install Carbon system | $37,000.00 | lump sum | $37,000.00 |
| Mobilize and Setup (CATOX) | $30,000.00 | lump sum | $30,000.00 |
| Mobilization for Drilling | $950.00 | lump sum | $950.00 |
| Drilling - Level D (150 feet) | $171.00 | 26.80 | $4,582.80 |
| Drilling Mobilization | $475.00 | lump sum | $475.00 |
| Vapor Extraction Well Casing and Seal (70 Feet) | $29.50 | 101.00 | $2,979.50 |
| Vapor Extraction Well Screen and Gravel Pack (80 Feet) | $38.70 | 70.00 | $2,709.00 |
| SVE System Hookup (per hookup) | $385.00 | 11.00 | $4,235.00 |
| Construction of Dual Groundwater SVE Well | $7,100.00 | lump sum | $7,100.00 |
| Construction of 2 Piezometer Well | $5,350.00 | lump sum | $5,350.00 |
| Construction of 3 Air Injection Well Nests | $6,925.00 | lump sum | $6,925.00 |
| Construction of EW-6 to Dual Extraction Well | $2,425.00 | lump sum | $2,425.00 |
| Installation of 20-ft fence gate | $1,450.00 | lump sum | $1,450.00 |
| Set-up and Mobilization of Sparging System | $7,375.00 | lump sum | $7,375.00 |
| Startup/Testing/Permits | |||
| Startup and Test SVE | $44,000.00 | lump sum | $44,000.00 |
| CATOX Startup | $25,000.00 | lump sum | $25,000.00 |
| SVE Well Monitoring System Restart (per day) | $1,500.00 | 3.00 | $4,500.00 |
| Operation (short-term - up to 3 years) | |||
| Operate Pilot Study | $31,000.00 | lump sum | $31,000.00 |
| 24 Month Operations | $175,000.00 | lump sum | $175,000.00 |
| Pilot Study Saturated Zone Sparging | $23,230.00 | lump sum | $23,230.00 |
| First Month of Operations | $11,480.00 | lump sum | $11,480.00 |
| January Sparging Operations | $9,039.00 | lump sum | $9,039.00 |
| February Sparging Operations | $6,526.43 | lump sum | $6,526.43 |
| March Sparging Operations | $9,180.00 | lump sum | $9,180.00 |
| April Sparging Operations | $8,748.00 | lump sum | $8,748.00 |
| Groundwater Extraction System Connection to Blower Seal Repair | $4,950.00 | lump sum | $4,950.00 |
| HDPE Piping & Conduit Repairs | $8,010.00 | lump sum | $8,010.00 |
| Contractor Oversight (per month) | $1,000.00 | 36.00 | $36,000.00 |
| Operation (long-term - over 3 years) | |||
| SVE Sytem Operation (per month) | $6,096.00 | 16.07 | $98,010.00 |
| Contractor Oversight (per month) | $1,000.00 | 20 | $20,000.00 |
| Cost of Ownership | |||
| Contract Execution | $14,000.00 | lump sum | $14,000.00 |
| Bond/Insurance | $54,000.00 | lump sum | $54,000.00 |
| Bonding | $33,200.00 | lump sum | $33,200.00 |
| Dismantling | |||
| Well Abandoment (per well) | $110.00 | 13 | $1,430.00 |
| Demobilization | |||
| SVE Manifold Piping Removal and Replacement (per foot) | $19.10 | 567 | $10,829.70 |
| SVE System Demobilization (per system) | $10,125.00 | 0.604 | $6,118.34 |
| Drilling Demobilization | $475.00 | lump sum | $475.00 |
| TOTAL | $1,645,281.17 | ||
Table 10. Actual Before-treatment Cost Elements [adapted from 17, 19]
| Activity | Unit Cost | Number of Units | Cost |
|---|---|---|---|
| Monitoring, Sampling, Testing, and Analysis | |||
| Daily Reporting | $2,000.00 | lump sum | $2,000.00 |
| Additional Soil Borings | $23,000.00 | lump sum | $23,000.00 |
| Additional Air Sampling | $75,000.00 | lump sum | $75,000.00 |
| Split Spoon Sampling During SVE Well Construction (per well) | $50.00 | 6 | $300.00 |
| Soil Sampling and Analysis Performed by ARCS Contractor | $150,000.00 | lump sum | $150,000.00 |
| Subsurface Investigation | $42,000.00 | lump sum | $42,000.00 |
| Soil Gas Survey | $5,500.00 | lump sum | $5,500.00 |
| Geophysical Study | $8,000.00 | lump sum | $8,000.00 |
| Site Work | |||
| Bail LNAPL | $2,000.00 | lump sum | $2,000.00 |
| Backfill and Compaction of spoils | $24,773.00 | lump sum | $24,773.00 |
| Backfill and Compaction of Clean Fill | $23,356.00 | lump sum | $23,356.00 |
| Packaging and Handling of Contaminated Soils (per package) | $110.62 | 2 | $221.24 |
| Drums/Tanks/Structures/Miscellaneous Demolition and Removal | |||
| Drum Disposal (per drum) | $950.00 | 4 | $3,800.00 |
| Excavation of USTs | $114,225.00 | lump sum | $114,225.00 |
| Tank Removal, Cleaning, and Disposal | $61,005.00 | lump sum | $61,005.00 |
| TOTAL | $535,180.24 | ||
As shown in Table 9, the vendor and contractor provided cost data that shows a total of $1,645,281 for cost elements directly associated with treatment of 26,700 cubic yards of soil treated (i.e., excluding before-treatment cost elements). This total treatment cost corresponds to $62 per cubic yard of soil treated, and to $37 per pound of contaminant removed (45,000 pounds). This calculated cost per cubic yard of soil treated is based on an estimate of the zone of influence of the extraction wells. The actual quantity of contaminated media is not available for comparison purposes. In addition, the vendor and contractor provided costs data that show a total of $535,180 for before-treatment costs. The vendor and contractor indicated that there were no costs in this application for after-treatment activities.
No information is contained in the available references on the costs for groundwater cleanup at Verona.
Actual treatment cost data for 11 WBS elements were provided
for this application. These costs are broken down into detailed activities
completed at Verona, and include costs incurred by both the treatment vendor
and oversight contractor.
Back to Treatment System Performance | Table of Contents | Forward to Observations and Lessons Learned
Back to Treatment System Cost | Table of Contents | Forward to References
This case study was prepared for the U.S. Environmental Protection Agency's Office of Solid Waste and Emergency Response, Technology Innovation Office. Assistance was provided by Radian Corporation under EPA Contract No. 68-W3-0001.
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