Florida Department of Environmental Protection (FDEP)
State of Florida, Department of Environmental Protection
200 Blair Stone Road
Tallahassee, FL 32399-2400
Guy Frearson, Program Manager
Metcalf & Eddy
13450 W. Sunrise Boulevard, Suite 200
Sunrise, FL 33323
Soil — Volatiles-Halogenated: Tetrachloroethene (PCE) [37,200 micrograms per kilogram (µg/kg)], Trichloroethene (TCE) [3,320 µg/kg], Cis-1,2-Dichloroethene.
Groundwater — Volatiles-Halogenated: Total Chlorinated Ethenes [225,589 micrograms per liter (µg/L)]; PCE [Concentration exceeded 20 percent of solubility (200,000 µg/L), indicating the presence of residual dense nonaqueous phase liquid (DNAPL)], TCE, Cis-1,2-Dichloroethene, Trans-1,2-Dichloroethene, Vinyl Chloride.
Dry cleaning operations.
Type/Quantity of Media Treated:
Purpose/Significance of Application:
The goal of the ISCO treatment was to reduce contaminants in groundwater to below the Natural Attenuation Default Criteria (NADC) concentrations. The goal of the in situ bio-stimulation treatment was to reduce contaminants to below the Groundwater Target Levels (GCTLs), which are based on the maximum contaminant levels (MCLs). The cleanup objective for soil was to reduce contaminant concentrations to below leachability regulatory levels for dry cleaning solvent contaminants.
Regulatory Requirements/Cleanup Goals:
NADC concentrations: PCE, 300 µg/L; TCE, 300 µg/L; Cis-1,2-Dichloroethene, 700 µg/L; Trans-1,2-Dichloroethene, 1000 µg/L; vinyl chloride, 100 µg/L.
Soil Leachability Levels: TCE, 30 µg/kg; PCE, 30 µg/kg; Cis-1,2-Dichloethene, 400 µg/kg.
GCTL concentrations: PCE, 3 µg/L; TCE, 3 µg/L; Cis-1,2-Dichloroethene, 70 µg/L; Trans-1,2-Dichloroethene, 100 µg/L; vinyl chloride, 1 µg/L.
-- Between April and July 2001, approximately 4.5 pounds of PCE and 11.3 pounds of total halogenated volatile organic compounds (VOCs) had been removed from the soil.
-- Approximately 17 pounds of PCE and 36 pounds of total halogenated VOCs were recovered between August and November 2001.
-- Approximately 13 pounds of PCE and 29 pounds of total halogenated VOCs were removed between November 2001 and February 2002.
-- Approximately 0.84 pounds PCE and 0.84 pounds of total halogenated VOCs were removed between February and April 2002.
-- No contaminants were detectable in the system blower effluent during the last two quarters of SVE operation. Substantial reduction in the soil contamination was also confirmed by soil samples collected in May 2002, where no contaminants were detected at concentrations above the leachability cleanup level.
-- After a year of SVE operation and limited excavation of highly contaminated soil, no further action was recommended for the soil at the site.
-- After the first full-scale injection in May 9, 2001 samples taken in June 2001 from 10 monitoring wells showed that total halogenated VOCs had been reduced by 79 percent. The June samples also showed some local increases of total halogenated VOCs in several wells.
-- Samples collected on January 21 and 22, 2002 after the second injection event (October 31, 2001) had similar results seen after the first injection. Overall concentrations of contaminants were further reduced, but there were some local increases in several wells.
-- The first round of sampling after the final injection event (April 11, 2002) was conducted on July 11 and 12, 2002. The samples showed that the injection continued to further reduce the overall contaminant concentrations, with results for all but eight wells exceeding the NADC.
-- The second round of sampling conducted after the final injection event on November 11 and 12, 2002. The data from this round of sampling showed that dissolved concentrations of contaminants rebounded overall between July and November. These results suggest that re-establishment of equilibrium conditions at the site is a slow process, possibly governed by the desorption and slow diffusion of contaminants from interior pore spaces into the portion of the aquifer subject to advective flow.
-- Overall, ISCO had reduced the overall size of the plume from 36 acres to 0.2 acre and successfully reduced the concentrations of PCE and TCE in the source area by an order of magnitude but not below the NADC.
In situ bio-stimulation:
-- The analytical results from samples taken after in situ bio-stimulation indicated that all VOC concentrations in groundwater were below the GCTLs except for vinyl chloride.
-- Total organic carbon levels were observed to be less than the ideal (20 milligrams per liter) in many of the sampling locations, likely indicating that ethyl lactate was being rapidly consumed, which could lead to less&emdash;than-optimal energy levels required to sustain reductive dechlorination.
The total cost for remediation of the site was $1,688,148. This total included $203,048 for the remedial investigation, $113,643 in design costs, $1,215,237 for implementation of the remedial action, and $136,220 in operation and maintenance costs. The total cost for the reductive dechlorination component (included in the total cost provided above) was $331,045, consisting of the pilot test, lactate injection at full scale, and groundwater monitoring.
Hanner's Dry Cleaners is an inactive dry cleaning facility in Pompano Beach, Florida that operated from the early 1960s to 1989. Conventional laundry machines were used at the facility and approximately 80 gallons of PCE were added into the dry cleaning machines every 2 weeks while the facility operated. After closing in 1989, the facility was included in the Florida Department of Environmental Protection (FDEP) Drycleaning Solvent Cleanup Program (DSCP).
A site assessment concluded that both soil and groundwater at the facility had been contaminated with halogenated VOCs and that the plume extended beyond the boundaries of the site. PCE in soil was detected at concentrations as high as 37,200 µg/kg, and TCE was detected at concentrations up to 3,320 µg/kg. Concentrations of total chlorinated ethenes in groundwater have been detected as high as 225,589 micrograms per liter µg/L in what has been identified as the core of the contamination plume. Concentrations of PCE in this area have also exceeded 20 percent of solubility (200,000 µg/L), indicating that residual DNAPL is likely to be present.
Initial site remediation consisted of limited excavation of accessible soil that exceeded the FDEP soil leachability cleanup goals along with SVE treatment of those soils remaining and ISCO treatment to reduce groundwater contamination in the core plume area to below NADC concentrations. SVE operated from April 2001 to May 2002 when it was determined that no further action was required for soil at the site. After three full scale ISCO injection events, conducted between May 2001 and April 2002, the overall size of the contaminated groundwater plume had been reduced from 36 acres to 0.2 acre and concentrations of PCE and TCE had been reduced in the source area by an order of magnitude but not below the NADC.
In June 2004, additional soil excavation was conducted in the source area to reduce DNAPL contamination and an in situ bio-stimulation pilot test was conducted in the excavated area. Four full scale in situ bio-stimulation injection events were conducted between February 2006 and April 2007. Analytical results from samples taken after the treatment indicated that all VOC concentrations in groundwater were below the GCTLs except for vinyl chloride. Additionally, total organic carbon levels were observed to be less than the ideal in many of the sampling locations, likely indicating that ethyl lactate was being rapidly consumed, which could lead to less—than-optimal energy levels required to sustain reductive dechlorination. It was recommended that in situ bio-stimulation treatment continue at the site but on a monthly basis. Additionally, it was recommended that another excavation be conducted to remove contaminated soil from underneath the concrete floor slab.
To date, the total cost for remediation of the site is $1,688,148. This total included $203,048 for the remedial investigation, $113,643 in design costs, $1,215,237 for implementation of the remedial action, and $136,220 in operation and maintenance costs.