Description
Historical activity that resulted
in contamination.
| PCE drycleaning operations were conducted at this site from October 1982 until June 2010. The facility was located in a shopping center in a mixed retail commercial/residential setting.
The operator had reported a PCE discharge realted to boilover of the distillation unit. The identified contaminant source areas are the drycleaning machine and the area outside the service door. Remediation Status: In active remediation |
Contaminants
Contaminants present and the highest amount
detected in both soil and groundwater.
| Contaminant |
Media |
Concentration (ppb) |
Nondetect |
| cis-1,2-Dichloroethene |
groundwater |
1 ppb |
|
| Tetrachloroethene (PCE) |
groundwater |
1 ppb |
|
| Tetrachloroethene (PCE) |
groundwater |
1 ppb |
|
| Trichloroethene (TCE) |
groundwater |
1 ppb |
|
| Vinyl Chloride |
groundwater |
1 ppb |
|
|
groundwater |
1 ppb |
|
|
groundwater |
1 ppb |
|
|
groundwater |
1 ppb |
|
|
soil |
1 ppb |
|
|
groundwater |
1 ppb |
|
|
groundwater |
1 ppb |
|
Site Hydrology
| Deepest Significant
Groundwater Contamination: |
|
40ft bgs |
| Plume Size: |
|
Plume Length: 1,100ft
Plume Width: 140ft
Plume Thickness: 30ft |
| Average Depth
to Groundwater: |
|
11.93ft |
Lithology and Subsurface Geology
|
|
very fine to fine-grained sand
Depth: 0-13ft bgs
13ft thick
Conductivity: 23.7ft/day
Gradient: 0.006ft/ft
|
|
|
silty very fine-grained sand with organics
Depth: 13-14.5ft bgs
1.5ft thick
|
|
|
very fine-grained sand
Depth: 14.5-32ft bgs
17.5ft thick
|
|
|
silty very fine to fine-grained sand
Depth: 32-36ft bgs
4ft thick
|
|
|
clayey silt to clay
Depth: 36-40ft bgs
4ft thick
|
Pathways and DNAPL Presence
 Groundwater
Sediments
Soil
 DNAPL 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): |
|
Passive Vapor Barrier
Sub-slab Depressurization
Sub-slab Pressurization
Passive Venting
HVAC controls/modifications
Soil Vapor Extraction
|
Remediation Scenario
Cleanup
Goals: |
|
Soil: PCE - 30 ug/kg
Groundwater: PCE - 3 ug/l, TCE - 3 ug/l, cis 1,2-DCE - 70 ug/l, vinyl chloride - 1 ug/l
|
Remedy Level: |
|
Full Scale Remedy |
Technologies
ex Situ Biostimulation |
|
Date implemented:
SVE system startup: July 7, 2004
Final remediation design:
Soil vapor extraction system: The system consists of seven (7) vapor extraction wells. Three of these wells were installed beneath the facilty floor slab (screened 1 - 8 ft below grade). Four vapor extraction wells (screened 3-8 ft BLS)were installed outside the exterior walls of the facility. The system is powered by a 5 HP regenerative Rotron blower. Off gas is treated via a 170-lb. G.A.C. unit. Design flow rate for the interior vapor extraction wells is 16 cfm/well @ 26-inches w.c. Design flow rate for the exterior wells is 12.5 cfm/well @ 26 inches w.c.
Other technologies used:
Potassium hydroxide was injected to buffer the groundwater at the site to enhance bioremediation.
Next Steps:
Continue to run the SVE system. Continue to monitor groundwater.
Cost to Design and Implement:
All technologies: Design: $28,100
Implementation: $280,100
|
ex Situ Soil Vapor Extraction |
|
Date implemented:
SVE system startup: July 7, 2004
Final remediation design:
Soil vapor extraction system: The system consists of seven (7) vapor extraction wells. Three of these wells were installed beneath the facilty floor slab (screened 1 - 8 ft below grade). Four vapor extraction wells (screened 3-8 ft BLS)were installed outside the exterior walls of the facility. The system is powered by a 5 HP regenerative Rotron blower. Off gas is treated via a 170-lb. G.A.C. unit. Design flow rate for the interior vapor extraction wells is 16 cfm/well @ 26-inches w.c. Design flow rate for the exterior wells is 12.5 cfm/well @ 26 inches w.c.
Next Steps:
Continue to run the SVE system. Continue to monitor groundwater.
Cost to Design and Implement:
All technologies: Design: $28,100
Implementation: $280,100
|
ex Situ Carbon Adsorption |
|
Date implemented:
SVE system startup: July 7, 2004
Final remediation design:
Soil vapor extraction system: The system consists of seven (7) vapor extraction wells. Three of these wells were installed beneath the facilty floor slab (screened 1 - 8 ft below grade). Four vapor extraction wells (screened 3-8 ft BLS)were installed outside the exterior walls of the facility. The system is powered by a 5 HP regenerative Rotron blower. Off gas is treated via a 170-lb. G.A.C. unit. Design flow rate for the interior vapor extraction wells is 16 cfm/well @ 26-inches w.c. Design flow rate for the exterior wells is 12.5 cfm/well @ 26 inches w.c.
Next Steps:
Continue to run the SVE system. Continue to monitor groundwater.
Cost to Design and Implement:
All technologies: Design: $28,100
Implementation: $280,100
|
ex Situ Soil Removal |
|
Date implemented:
SVE system startup: July 7, 2004
Final remediation design:
Soil vapor extraction system: The system consists of seven (7) vapor extraction wells. Three of these wells were installed beneath the facilty floor slab (screened 1 - 8 ft below grade). Four vapor extraction wells (screened 3-8 ft BLS)were installed outside the exterior walls of the facility. The system is powered by a 5 HP regenerative Rotron blower. Off gas is treated via a 170-lb. G.A.C. unit. Design flow rate for the interior vapor extraction wells is 16 cfm/well @ 26-inches w.c. Design flow rate for the exterior wells is 12.5 cfm/well @ 26 inches w.c.
Next Steps:
Continue to run the SVE system. Continue to monitor groundwater.
Cost to Design and Implement:
All technologies: Design: $28,100
Implementation: $280,100
|
ex Situ Carbon Adsorption |
|
Date implemented:
SVE system startup: July 7, 2004
Final remediation design:
Soil vapor extraction system: The system consists of seven (7) vapor extraction wells. Three of these wells were installed beneath the facilty floor slab (screened 1 - 8 ft below grade). Four vapor extraction wells (screened 3-8 ft BLS)were installed outside the exterior walls of the facility. The system is powered by a 5 HP regenerative Rotron blower. Off gas is treated via a 170-lb. G.A.C. unit. Design flow rate for the interior vapor extraction wells is 16 cfm/well @ 26-inches w.c. Design flow rate for the exterior wells is 12.5 cfm/well @ 26 inches w.c.
Next Steps:
Continue to run the SVE system. Continue to monitor groundwater.
Cost to Design and Implement:
All technologies: Design: $28,100
Implementation: $280,100
|
ex Situ Carbon Adsorption |
|
Date implemented:
SVE system startup: July 7, 2004
Final remediation design:
Soil vapor extraction system: The system consists of seven (7) vapor extraction wells. Three of these wells were installed beneath the facilty floor slab (screened 1 - 8 ft below grade). Four vapor extraction wells (screened 3-8 ft BLS)were installed outside the exterior walls of the facility. The system is powered by a 5 HP regenerative Rotron blower. Off gas is treated via a 170-lb. G.A.C. unit. Design flow rate for the interior vapor extraction wells is 16 cfm/well @ 26-inches w.c. Design flow rate for the exterior wells is 12.5 cfm/well @ 26 inches w.c.
Next Steps:
Continue to run the SVE system. Continue to monitor groundwater.
Cost to Design and Implement:
All technologies: Design: $28,100
Implementation: $280,100
|
ex Situ Carbon Adsorption |
|
Date implemented:
SVE system startup: July 7, 2004
Final remediation design:
Soil vapor extraction system: The system consists of seven (7) vapor extraction wells. Three of these wells were installed beneath the facilty floor slab (screened 1 - 8 ft below grade). Four vapor extraction wells (screened 3-8 ft BLS)were installed outside the exterior walls of the facility. The system is powered by a 5 HP regenerative Rotron blower. Off gas is treated via a 170-lb. G.A.C. unit. Design flow rate for the interior vapor extraction wells is 16 cfm/well @ 26-inches w.c. Design flow rate for the exterior wells is 12.5 cfm/well @ 26 inches w.c.
Next Steps:
Continue to run the SVE system. Continue to monitor groundwater.
Cost to Design and Implement:
All technologies: Design: $28,100
Implementation: $280,100
|
ex Situ Soil Removal |
|
Why the technology was selected:
Excavation was selected because contaminated sediments were easily accessible.
Date implemented:
Excavation: May 4, 2004
Final remediation design:
Approximately 1 cubic yard of contaminated sediment was excavated in the vicinity of the water meter box.
Next Steps:
Continue to run the SVE system. Continue to monitor groundwater.
Cost to Design and Implement:
All technologies: Design: $28,100
Implementation: $280,100
|
in Situ Soil Vapor Extraction |
|
Why the technology was selected:
Soil vapor extraction was selected because contaminated soils were permeable and there is a relatively deep water table at the site.
Date implemented:
SVE system startup: July 7, 2004
Final remediation design:
Soil vapor extraction system: The system consists of seven (7) vapor extraction wells. Three of these wells were installed beneath the facilty floor slab (screened 1 - 8 ft below grade). Four vapor extraction wells (screened 3-8 ft BLS)were installed outside the exterior walls of the facility. The system is powered by a 5 HP regenerative Rotron blower. Off gas is treated via a 170-lb. G.A.C. unit. Design flow rate for the interior vapor extraction wells is 16 cfm/well @ 26-inches w.c. Design flow rate for the exterior wells is 12.5 cfm/well @ 26 inches w.c.
Results to date:
Buffering was successful. The pH of the injection zone was raised from approximately 4.5 standard units (SU) to as high as 7.2 SU)but generally to 6.2 to 6.2 SU. In general, these higher pH values were sustained for up 7 months after the injection events.
Contaminant concentrations in groundwater had dropped prior to commencement of injection. Highest PCE concentrations prior injection were 123 ug/l PCE, 27 ug/l TCE & 2 ug/l cis 1,2-DCE.
PCE concentrations dropped an order of magnitude after the injections. However, no dicernable increase in daughter products was observed.
The SVE system is still operating. Focus is on operating the vapor extraction wells installed beneath the facility floor slab.
The latest groundwater monitoring event was conducted on October 21, 2009. Only one monitor well produced a groundwater sample with a contaminant concentration exceeding an MCL: 13 ug/l PCE.
Next Steps:
Continue to run the SVE system. Continue to monitor groundwater.
Cost to Design and Implement:
All technologies: Design: $28,100
Implementation: $280,100
|
in Situ Biostimulation |
|
Why the technology was selected:
Biostimulation was selected because anaerobic conditions exist in the aquifer and PCE daughter products were present, indicating that reductive dechlorination was an active process in groundwater. The highest contaminant concentrations in groundwater were in the fine-grained sand with organics at 13 - 14.5 ft BLS. This unit has a high oxidant demand which precluded the use of chemical oxidation as a remedy.
Buffering was implemented because the pH of the groundwater generally ranged from 4.5 to 5.8 standard units which was believed to be inhibiting biodegradation.
Date implemented:
Potassium hydroxide buffering events; April 27-30, 2004; May 12-14, 2004, July 25-29, 2005, August 8-12, 2005
Potassium lactate injection events: May 24-25, 2004; August 25-26, 2004; August 23-27, 2005; September 19-22, 2005.
Final remediation design:
The biostimulation injection well network consisted of 20 wells. One of these wells was screened 5-15 ft BLS, but the other 19 wells had two feet of screen across an organic rich fine-grained sand. The gross interval across which the injection wells are screened is 10.74 - 14.73 ft BLS. The bulk of the contaminant mass is sorbed on these organics. The injection wells are installed in three rows oriented perpendicular to groundwater flow. One row (Zone I) has six injection wells which are installed behind or immediately upgradient of the drycleaning facility. Zone II consists of six wells installed immediately down gradient of the facilty and Zone III consists of 8 wells installed approximately 130 feet hydraulically downgradient of the facility.
Four buffering injection events were conducted. The first two buffering injection events were conducted in the upgradient (Zone I) injection wells. In the first event, 12 liters of 1 Normal potassium hydroxide and 1,632 gallons of water (total) were injected into the six Zone I injection wells. In the second buffering event, approximatley 1.6 liters of 1 Normal potassium hydroxide plus 1,632 gallons of water were injected into the Zone I wells. The two buffering injection events were followed by the first and second potassium lactate injection events.
After two potassium lactate injection events were conducted the final two buffering injection events were conducted. All 20 injection wells were utilized.
Four potassium lactate injection events were conducted at the site. The first two K-lactate injection events were conducted in Zone I (up gradient) 6 injection wells. Each of these events utilized a total of approximately 140 gallons of 60% K-lactate solution and 2,700 gallons of water.
The last two K-lactate injection events included all three injection zones (20 injection wells) and used approximately 300 gallons of 60% k-lactate solution and 6,400 gallons of water.
In the third potassium lactate injection event, each Zone I well received 1 liter of 1 Normal potassium hydroxide plus 350 gallons of water. Each Zone II well received 1 liter of 1 Normal potassiium hydroxide plus 320 gallons of watgr. Each Zone III well received 1 liter of potassium hydroxide solution plus 150 gallons of water.
In the fourth and final potassium lactate injection event, each Zone I well received 1 liter of 1 Normal potassium hydroxide plus 500 gallons of water; each Zone II and Zone III well received 1 liter of 1 Normal potassium hydroxide plus 175 gallons of water.
Results to date:
Buffering was successful. The pH of the injection zone was raised from approximately 4.5 standard units (SU) to as high as 7.2 SU)but generally to 6.2 to 6.2 SU. In general, these higher pH values were sustained for up 7 months after the injection events.
Contaminant concentrations in groundwater had dropped prior to commencement of injection. Highest PCE concentrations prior injection were 123 ug/l PCE, 27 ug/l TCE & 2 ug/l cis 1,2-DCE.
PCE concentrations dropped an order of magnitude after the injections. However, no dicernable increase in daughter products was observed.
The SVE system is still operating. Focus is on operating the vapor extraction wells installed beneath the facility floor slab.
The latest groundwater monitoring event was conducted on October 21, 2009. Only one monitor well produced a groundwater sample with a contaminant concentration exceeding an MCL: 13 ug/l PCE.
Next Steps:
Continue to run the SVE system. Continue to monitor groundwater.
Cost to Design and Implement:
All technologies: Design: $28,100
Implementation: $280,100
|
Costs
Cost
for Assessment:
|
|
$164,100 |
Cost
for Operation and Maintenance:
|
|
Annual O&M (includes monitoring): $47,700 |
Total
Costs for Cleanup:
|
|
|
Lessons Learned
1. We would install additional performance monitoring wells in the contaminant source area including a monitor well beneath the facility floor slab. Since the Zone I injection wells were located on the up gradient side of the facility, we did not have optimally located performance monitoring wells to track performance in Zone I.
2. We would conduct more extensive baseline sampling, including sampling more injection wells.
3. We would recommend sampling for total organic carbon and total dissolved solids to monitor potassium lactate distribution/persistance.
4. Biostimulation was not effective at this site, with low contaminant concentrations. PCE, is still present in groundwater but concentrations of PCE daughter products are below regulatory levels.
|
Contacts
Aaron Cohen
Florida Dept. of Environmental Protection
Bureau of Waste Cleanup, MS 4500
2600 Blair Stone Road
Tallahassee, Florida 32399
850-245-8974
Aaron.Cohen@dep.state.fl.us
Contractor:
Nana Westmark
PSI
5801 Benjamin Center Drive Suite 112
Tampa, Florida 33634
(813) 886-1075
nana.westmark@psiusa.com
|
Site Specific References
Site Assessment Report: 2001
Remedial Action Plan: 2003
O&M Reports: 2004 - 2010
Groundwater Monitoring Reports: 2002 - 2010
Cline, Donna M, P. Jackson, M. Collins. KOH Injections in Low pH Aquifers to Enhance Anaerobic Degradation. June 6-9, 2003. Baltimore: Proceedings of the Eighth International On-Site Bioremediation Symposium.
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