Drycleaner Site Profiles

Former 60 Minute Cleaners (College), Fort Myers, Florida

Description
Historical activity that resulted in contamination.

Drycleaning using PCE was performed at this site from 1968 until 1999. The site is located in a strip mall in a commercial-retail/residential setting. A gas station was formerly located adjacent to the strip mall and petroleum contaminants are comingled with the chlorinated solvent contamination. An active PCE drycleaning facility is located immediately hydraulically up gradient of the site and is cuurently undergoing remediation (soil vapor extraction). The contaminant source area is the soil beneath the facility floor slab near the former location of the drycleaning machine. Five water supply wells are located within one-half mile of the site. The nearest well is located approximately 500 ft from the site and produces from a zone 200-400 ft bgs.

Remediation Status: In groundwater monitoring


Contaminants
Contaminants present and the highest amount detected in both soil and groundwater.


Contaminant Media Concentration (ppb) Nondetect
Benzene groundwater 150 ppb
cis-1,2-Dichloroethene groundwater 2,321 ppb
1,1-Dichloroethene groundwater 1,050 ppb
ethylbenzene groundwater 2.5 ppb
No corresponding contaminant groundwater 29.5 ppb
Tetrachloroethene (PCE) groundwater 6,820 ppb
Tetrachloroethene (PCE) soil 1,800 ppb
Trichloroethene (TCE) groundwater 2,040 ppb
Trichloroethene (TCE) soil 2.97 ppb
toluene groundwater 6.9 ppb
trans-1,2-Dichloroethene groundwater 150 ppb
Vinyl Chloride groundwater 645 ppb
xylenes groundwater 4 ppb

Site Hydrology

Deepest Significant Groundwater Contamination:   44ft bgs
Plume Size:   Plume Length: 225ft
Plume Width: 500ft
Average Depth to Groundwater:   4ft

Lithology and Subsurface Geology

 
  Silty, fine-grained sand
Depth: 0-2.5ft bgs
2.5ft thick
Conductivity: 29.5ft/day
Gradient: 0.001ft/ft
 
  Limestone caprock
Depth: 2.5-11ft bgs
8.5ft thick
 
  Silty, fine-grained sand with shells and limestone stringers
Depth: 11-27ft bgs
16ft thick
Conductivity: 29.5ft/day
 
  Sandy clay
Depth: 27-35ft bgs
8ft thick
 
  Clay
Depth: 35-44ft bgs
9ft thick

Pathways and DNAPL Presence

checkGroundwater
Sediments
checkSoil
checkDNAPL Present

Vapor Intrusion Pathway

Has the potential for vapor intrusion (VI) been evaluated?
  No
Has a vapor mitigation system been installed?
  Yes 
Type of Vapor Mitigation System(s):
  Soil Vapor Extraction

Remediation Scenario

Cleanup Goals:
  Groundwater: PCE = 3 µg/l, TCE = 3 µg/l, cis 1,2-DCE = 70 µg/l, trans 1,2-DCE = 100 µg/l, 1,1-DCE = 7 µg/l, vinyl chloride = 1.0 µg/l

Soil: PCE = 30 ug/kg; TCE = 30 ug/kg
Remedy Level:
  Full Scale Remedy

Technologies

In Situ Bioremediation
 

Why the technology was selected:
In-situ bioremediation via ethyl lactate injection/groundwater withdrawal and re-injection was chosen, because anaerobic conditions existed in the aquifer and reductive dechlorination was occurring. Ethyl lactate was chosen to stimulate biodegradation, because it is a relatively cheap carbon source. Groundwater withdrawal/injection was chosen to facilitate distibution of the ethyl lactate within the relatively heterogeneous aquifer.

Date implemented:
March 12, 2003

Final remediation design:
Groundwater remedial system: Twenty-two (22) injection wells constructed of 4-inch diameter, schedule-40 PVC were installed outside the south and west walls of the facility (hydraullically upgradient). Fifteen (15)shallow injection wells were screened 10-20 ft bgs with 0.10-inch slot. Seven deep injection wells were screened 30-40 ft bgs with 0.01-inch slot screen. Two recovery wells were installed outside the north (downgradient) side fo the facility. They were constructed of 5-inch diameter, Schedule-40 PVC with 0.020-inch slot screen. One well was completed in the shallow portion of the aquifer (5-20 ft bgs) and one well was completed in the deeper portion of the aquifer (25-40 ft bgs). A 1/3-horsepower Grunfos 10E-5 submersible pump was installed in the shallow recovery well and a 1/2-horsepower Grunfos 16-E submersible pump was installed in the deeper recovery well. The design recovery well pumping rates were 8 and 7 gpm for the shallow and deep wells, respectively. Recovered groundwater is treated in two 1000-lb liquid carbon vessels and then routed to a 300-gallon poly transfer tank where it is aerated to treat for vinyl chloride and then re-injected (into site injection wells) with a 1.5-horsepower Gould pump.

Results to date:
The SVE system operated from March 12, 2003 until September 6, 2005. The system operated at an average of 120 scfm at 13 inches of water column. The calculated radius of influence for each well was over 20 ft. Approximately 22.7 pounds of VOCs (99% PCE) were removed during the system operation. A total of thirteen (13) ethyl lactate injection events between March 2003 and March 2007. A total of 110 gallons of ethyl lactate was injected during each event (55 gallons in the shallow injection well and 55 gallons in the deep injection well) in a 1-2% solution. Ethanol was detected in recovery wells within one week of the initial injection event. Within three weeks of the first injection event, ethanol was not being detected in recovery wells. There was a rapid decrease in PCE concentrations in system influent in the first quarter of system operation coupled with an increase of cis 1,2-DCE in groundwater influent concentrations. Cis 1,2-DCE concentrations in groundwater influent began decreasing late in the first quarter of system operation, and vinyl chloride concentrations increased substantially. Vinyl chloride concentrations began to decrease in the fourth quarter of system operation. The groundwater extraction system was turned off on October 14, 2005. During the 2 ½ years of operation 9,621,700 gallons of groundwater were recovered for an average overall system flow rate of 9.8 gpm. Approximately 31 lbs. of VOCs were recovered during the system operation; the estimated total mass within the groundwater during the remedial action plan was 19.8lbs. System Influent Concentrations (in µg/l): 3/13/03--1,080 PCE, 991 TCE, 318 cis DCE, 8 trans DCE, 22 vinyl chloride. No PCE was detected in groundwater samples collected during the March 18, 2008 sampling event. The highest TCE concentration found was 3 ug/l. No contaminants were found in the contaminant source area in concentrations exceeding an MCL. The highest contaminant concentrations in groundwater were detected in monitor wells located from 120 to over 200 feet hydraulically down gradient of the former facility: 1,000 ug/l Cis 1,2-DCE and 65 ug/l vinyl chloride. The highest contaminant concentration that exceeded an MCL that was detected in a groundwater sample collected from an offsite monitor well was 2 ug/l vinyl chloride.

Next Steps:
Continue natural attenuation monitoring.

Cost to Design and Implement:
all technologies: Design: $32,300 Construction: $107,500

In Situ Monitored Natural Attenuation
 

Why the technology was selected:
Natural attenation was chosen as the remedy for the distal portion of the contaminant plume. Since reductive dechlorination is occurring, treatment of high contaminant concentrations in the source area coupled with natural attenuation of the low contaminant concentrations in the distal portion of the plume should remediate the plume.

Next Steps:
Continue natural attenuation monitoring.

Cost to Design and Implement:
all technologies: Design: $32,300 Construction: $107,500

Ex Situ Carbon Adsorption
 

Date implemented:
March 12, 2003

Final remediation design:
SVE - Three 20-ft horizontal SVE wells constructed of 2-inch diameter, schedule-40 PVC were installed (one on each of three sides of the former facility) in a 2-ft-deep trench. The system is powered by a 2-horsepower Rotron EN505 230 blower. Off gas is treated via two 170-lb GAC units. The design flow rate is 90 scfm at 20 inches of water column vacuum. The design radius of influence for each SVE well is 20 ft.

Results to date:
The SVE system operated from March 12, 2003 until September 6, 2005. The system operated at an average of 120 scfm at 13 inches of water column. The calculated radius of influence for each well was over 20 ft. Approximately 22.7 pounds of VOCs (99% PCE) were removed during the system operation.

Next Steps:
Continue natural attenuation monitoring.

Cost to Design and Implement:
all technologies: Design: $32,300 Construction: $107,500

Ex Situ Pump and Treat
 

Why the technology was selected:
In-situ bioremediation via ethyl lactate injection/groundwater withdrawal and re-injection was chosen, because anaerobic conditions existed in the aquifer and reductive dechlorination was occurring. Ethyl lactate was chosen to stimulate biodegradation, because it is a relatively cheap carbon source. Groundwater withdrawal/injection was chosen to facilitate distibution of the ethyl lactate within the relatively heterogeneous aquifer.

Date implemented:
March 12, 2003

Final remediation design:
Groundwater remedial system: Twenty-two (22) injection wells constructed of 4-inch diameter, schedule-40 PVC were installed outside the south and west walls of the facility (hydraullically upgradient). Fifteen (15)shallow injection wells were screened 10-20 ft bgs with 0.10-inch slot. Seven deep injection wells were screened 30-40 ft bgs with 0.01-inch slot screen. Two recovery wells were installed outside the north (downgradient) side fo the facility. They were constructed of 5-inch diameter, Schedule-40 PVC with 0.020-inch slot screen. One well was completed in the shallow portion of the aquifer (5-20 ft bgs) and one well was completed in the deeper portion of the aquifer (25-40 ft bgs). A 1/3-horsepower Grunfos 10E-5 submersible pump was installed in the shallow recovery well and a 1/2-horsepower Grunfos 16-E submersible pump was installed in the deeper recovery well. The design recovery well pumping rates were 8 and 7 gpm for the shallow and deep wells, respectively. Recovered groundwater is treated in two 1000-lb liquid carbon vessels and then routed to a 300-gallon poly transfer tank where it is aerated to treat for vinyl chloride and then re-injected (into site injection wells) with a 1.5-horsepower Gould pump.

Results to date:
A total of thirteen (13) ethyl lactate injection events between March 2003 and March 2007. A total of 110 gallons of ethyl lactate was injected during each event (55 gallons in the shallow injection well and 55 gallons in the deep injection well) in a 1-2% solution. Ethanol was detected in recovery wells within one week of the initial injection event. Within three weeks of the first injection event, ethanol was not being detected in recovery wells. There was a rapid decrease in PCE concentrations in system influent in the first quarter of system operation coupled with an increase of cis 1,2-DCE in groundwater influent concentrations. Cis 1,2-DCE concentrations in groundwater influent began decreasing late in the first quarter of system operation, and vinyl chloride concentrations increased substantially. Vinyl chloride concentrations began to decrease in the fourth quarter of system operation. The groundwater extraction system was turned off on October 14, 2005. During the 2 ½ years of operation 9,621,700 gallons of groundwater were recovered for an average overall system flow rate of 9.8 gpm. Approximately 31 lbs. of VOCs were recovered during the system operation; the estimated total mass within the groundwater during the remedial action plan was 19.8lbs. System Influent Concentrations (in µg/l): 3/13/03--1,080 PCE, 991 TCE, 318 cis DCE, 8 trans DCE, 22 vinyl chloride. No PCE was detected in groundwater samples collected during the March 18, 2008 sampling event. The highest TCE concentration found was 3 ug/l. No contaminants were found in the contaminant source area in concentrations exceeding an MCL. The highest contaminant concentrations in groundwater were detected in monitor wells located from 120 to over 200 feet hydraulically down gradient of the former facility: 1,000 ug/l Cis 1,2-DCE and 65 ug/l vinyl chloride. The highest contaminant concentration that exceeded an MCL that was detected in a groundwater sample collected from an offsite monitor well was 2 ug/l vinyl chloride.

Next Steps:
Continue natural attenuation monitoring.

Cost to Design and Implement:
all technologies: Design: $32,300 Construction: $107,500

Ex Situ Soil Vapor Extraction
 

Why the technology was selected:
SVE is an effective technology for removal of VOCs from permeable unsaturated sediments.

Date implemented:
March 12, 2003

Final remediation design:
SVE - Three 20-ft horizontal SVE wells constructed of 2-inch diameter, schedule-40 PVC were installed (one on each of three sides of the former facility) in a 2-ft-deep trench. The system is powered by a 2-horsepower Rotron EN505 230 blower. Off gas is treated via two 170-lb GAC units. The design flow rate is 90 scfm at 20 inches of water column vacuum. The design radius of influence for each SVE well is 20 ft.

Results to date:
The SVE system operated from March 12, 2003 until September 6, 2005. The system operated at an average of 120 scfm at 13 inches of water column. The calculated radius of influence for each well was over 20 ft. Approximately 22.7 pounds of VOCs (99% PCE) were removed during the system operation.

Next Steps:
Continue natural attenuation monitoring.

Cost to Design and Implement:
all technologies: Design: $32,300 Construction: $107,500

Costs

Cost for Assessment:
  Site Assessment: $209,900
Cost for Operation and Maintenance:
  O&M - first two years (includes ethyl lactate, SVE, GW recovery, GW monitoring, reporting & utilities): $166,000 O&M ethyl lactate injection, GW monitoring, and reporting: $30,000 per year
Total Costs for Cleanup:
 

Lessons Learned

1. During site assessment, a solid stem auger was used to drill pilot holes in the the limestone caprock that allowed for direct push groundwater profiling of the deeper portion of the aquifer.

2. Long delays occurred in obtaining various permits from local government agencies. Changes in the building codes caused addtional delays.

3. The orignal choice for an injectant was spirits-grade ethanol; however, ethyl lactate was chosen as the enhanced-dechlorination additive because of costs and time associated with the request for procurement of a small amount of ethanol.

Contacts

Jennifer Farrell, Environmental Manager
Bureau of Waste Cleanup (MS4520)
Florida Department of Environmental Protection
2600 Blair Stone Road
Tallahassee, Florida 32399-2400
phone: (850) 245-8927
jennifer.a.farrell@dep.state.fl.us

Kevin Warner, P.E. consultant
LFR Levine Fricke, Inc.
3382 Capital Circle, N.E.
Tallahassee, Florida 32308-1568
(850) 422-2555

Site Specific References

Site Assessment Report: July 1999
Remedial Action Plan: December 2001
Remediation System Startup Report: Dec. 2003
Remediaiton System Status Reports 2003-2007

Groundwater Monitoring Reports: to 2008