- The SVE system included vapor extraction wells and vacuum transmission lines to a SVE trailer that included control valves, a moisture separator, a vacuum blower, a particulate filter, and a carbon treatment unit.
- Eleven horizontal SVE wells were constructed with a 4-inch inside diameter PVC piping. The well screens were 10 or 15 feet in length and had a screen slot diameter of 0.02 inches.
- The SVE wells were installed approximately 2 feet below ground surface (bgs).
- The system was powered by a 7.5 horsepower blower.
- The bioremediation process used a total of 21 vertical injection points. The SVE wells, along with injection wells and monitoring wells, were used as injection points.
- A series of six injection events were conducted and the bioremediation injection amounts varied for each event. A total of 88,800 gallons of ground water and nutrient amendments were injected during the six injection events.
- The nutrient amendment consisted of potassium lactate and denatured ethanol to serve as a carbon and energy source to support the growth and activity of chlororespiratory microbes at the site.
- During each injection, the amendment was mixed with 300 gallons of water for each injection well and flushed with water to clear the screen.
- During the first four injection events, the solution consisted of 299 gallons of ground water, 0.8 gallons of 60% potassium lactate solution, and 0.2 gallons of 90% ethanol solution.
- During the fifth and sixth injection event, the solution consisted of 298 gallons of ground water, 1.5 gallons of 60% potassium lactate and 0.2 gallons of 90% denatured ethanol.
FDEP State Cleanup
DEP, Bureau of Waste Cleanup
Drycleaning Solvent Cleanup Program
Blair Stone Road, MS 4520
Tallahassee, FL 32399-2400
John E. Dottellis
Golder Associates Inc.
8933 Western Way, Suite 12
Jacksonville, FL 32256
Michael P. Skeean, Jr.
Harding Lawson Associates
Berkley Building, 2590 Executive Center Circle East
Tallahassee, FL 32301
Tetrachlorethene (PCE), Trichloroethene (TCE), cis-1,2-Dichloroethene (cis-1,2-DCE), and Vinyl Chloride
Historical drycleaning operations and practices associated with the former Beaches Laundry and Cleaners.
Type/Quantity of Media Treated:
Groundwater (quantity not documented) and soil (quantity not documented).
Purpose/Significance of Application:
Soil excavation and SVE were used to address Volatile Organic Soil excavation and SVE were used to address Volatile Organic Compounds (VOCs) in soil at the site; enhanced bioremediation was the technology selected to address VOCs in the ground water associated with a large contaminant plume at the site.
Excavation and SVE were included in the remedial design to accelerate the removal of mass from the source area. The SVE system was designed to address soil contamination in the vadose zone of the site and portions of the site that could not be excavated due to building structural concerns and the shallow ground water table. In situ enhanced bioremediation was used to expedite the bioremediation process in the dissolved phase (down gradient) portion of the plume through the addition of nutrient amendments.
Regulatory Requirements/Cleanup Goals:
The goals of the remedial action plan were to reduce PCE, TCE, 1-2 cis DCE, and VC contamination in the soil to the Florida Soil Cleanup Target Levels (FSCTLs) shown in Table 1. The goal for ground water was to achieve concentrations below the Florida Natural Attenuation Default Criteria (FNADCs) shown in Table 3, which would eventually achieve the Florida Groundwater Cleanup Target Levels (FGCTLs) shown on Table 2 through natural attenuation.
Table1: Florida Soil Cleanup Target Levels
Table2: Florida Ground Water Cleanup Target Levels
|Vinyl Chloride (VC):||1µg/kg|
Notes: µg/L— Microgram per liter
Table3: Ground Water Natural Attenuation Default Criteria
|Vinyl Chloride (VC):||100µg/kg|
µg/kg—Microgram per kilogram
Air samples from the SVE system were collected monthly from April 2007 to September 2007. Analytical results from these samples indicated the following:
- PCE concentrations in the influent ranged from below detection limit (bdl) to 3.91 mg/m3.
- PCE concentrations in the effluent ranged from bdl to 1.73 mg/m3. Effluent air vapor was treated using an air filter system and activated carbon system.
- From February 5, 2007 to September 30, 2007, the system removed a total mass of 4.63 pounds (lbs) of VOCs.
- The average mass removal rate was 0.0005 lbs/day at an average air influent flow rate of 200 cubic feet per minute (cfm).
Samples obtained in July 2008 and September 2008 indicated non-detect levels of methane. In addition, PCE levels were determined to be non-detectable in the influent. As a result, the SVE system was shut off and converted to a passive system in March 2009.
Enhanced Bioremediation Monitoring
Ground water monitoring was conducted on July 1-2, 2008 (about a month after the final injection at the site). A total of twenty-one monitoring wells were sampled. The samples were compared to baseline data collected before the injection process to determine the percent reduction. Analytical results from the 2006 baseline monitoring event and post injection monitoring event in 2008 show the following:
- The potassium lactate and denatured ethanol amendments were effective in accelerating the biodegradation of PCE and PCE degradation products. The total VOC reduction ranged from 65 to 99% in the shallow zone wells.
- Cis-1,2 DCE concentrations after the injections ranged from 6.2 µg/L to 890 µg/L. The cis-12 DCE concentration of 890 µg/L located downgradient from the source area is the only shallow zone FNADC exceedance among the wells sampled in July 2008.
- The reductions in cis-1,2 DCE along with the TCE and PCE reductions indicate a significant mass transformation at the site.
- VC concentrations increased due to biological reductive dechlorination of PCE and TCE.
- TCE concentrations were also significantly reduced, ranging from bdl to approximately 21 µg/L. The TCE GCTL was exceeded at only two groundwater monitoring well locations.
- At groundwater monitoring wells installed in the deep zone of the site aquifer, sampling data indicated significant increases in PCE, TCE and cis-1,2 DCE concentration compared to baseline data, suggesting that additional contaminant mass may have been released from the aquifer.
Post injection monitoring results indicate that the bioremediation program has been effective in establishing reducing conditions and achieving reductive dechlorination of VOCs over most of the treated area. As of July 2008, PCE and TCE concentrations exceed the FNADCs at several locations within the intermediate and deep aquifer levels. However, results indicate that these concentrations are continuing to decrease.
The cost estimate for the phased remediation plan is presented below. The cost includes capital costs, construction costs, operation and maintenance (O&M) costs, and monitoring costs. Costs are based on the vendors selected and the operational life of the remedial system.
|Soil excavation and source area well installation total||$299,000|
Phased Enhanced Bioremediation System:
|SVE capital costs||$40,000|
|Well Installation/Baseline sampling||$73,700|
|One lactate injection||$2,700|
|O&M for one year||$39,000|
|2007 Well installation||$8,000|
|2008 Six Monthly Lactate Injections/Monitoring||$138,000|
|2009 Well Installation||$43,000|
|Baseline groundwater sampling||$12,000|
|Four Quarterly Injections/Sampling||$78,000|
Beaches operated in a building located at 106 North 6th Street in Jacksonville Beach, Florida in an area of mixed commercial and residential development. Since the end of drycleaning operations in 1990, the building has been used for a variety of commercial purposes such as a skating and skateboarding recreational center and a community theater. Past drycleaning operations (1950 to 1990) resulted in VOC contaminated soil and groundwater at the site. Analytical results from a ground water sample collected during an initial site screening assessment conducted in the fall of 1996 indicated the presence of PCE and VC. Based on these results, Beaches became eligible for cleanup under the Drycleaning Solvent Cleanup Program (DSCP) in January 13, 1997. Further contamination assessments indicated extensive ground water contamination in a large plume with VOC concentrations that exceeded the FGCTLs. The contaminated ground water plume was 300 to 450 feet wide and extended southwesterly for a distance of approximately 700 feet from the northeast corner of the site building.
After a failed chemical oxidation pilot test at the site, a revised remedial action plan was recommended. The revised remedial action for this site included a phased approach, with excavation of contaminated soil followed by an SVE system to address VOCs in the soil and accelerate source mass removal. Following soil excavation in 2004, the SVE system began operation on February 7, 2007 to address remaining soil contamination in the vadose zone of the site. For the groundwater, enhanced in situ bioremediation was planned to achieve the FNADC, which would allow active treatment to be discontinued and allow natural attenuation to achieve FGCTLs. During the enhanced bioremediation, a series of six injection events were implemented between January and June 2008 (one event per month).
Baseline and post injection monitoring was conducted at the site for both the SVE and enhanced bioremediation system. As of July 2008, the cleanup goals for the site had not been met. PCE and TCE concentrations exceeded the FNADCs at several locations within the intermediate and deep aquifer levels. However, results indicate that the phased remedial action at the site has resulted in significant reductions in the levels of contamination that were present at the site and that these concentrations are continuing to decrease.