Description
Historical activity that resulted
in contamination.
| PCE drycleaning operations were conducted at this site from 1978 until 1995 and then from December of 1997 until 2008. In November 1994, a 150 gallon AST that held PCE was reportedly vandalized and an estimated 15 - 20 gallons of PCE was discharged to the ground. This tank was located just outside the rear door of the drycleaning facility.
The drycleaning business was located in a small building that shares a common wall with a convenience store with documented petroleum contamination. The site is located in a mixed retail commercial/residential setting.
The identified contaminant source areas are the former location of the AST and the soil beneath the building floor slab. Remediation Status: In groundwater monitoring |
Contaminants
Contaminants present and the highest amount
detected in both soil and groundwater.
| Contaminant |
Media |
Concentration (ppb) |
Nondetect |
| cis-1,2-Dichloroethene |
groundwater |
|
|
| ethylbenzene |
soil |
|
|
| Tetrachloroethene (PCE) |
groundwater |
|
|
| Tetrachloroethene (PCE) |
soil |
|
|
| Trichloroethene (TCE) |
groundwater |
|
|
| Trichloroethene (TCE) |
soil |
|
|
| p-Xylene |
soil |
|
|
Site Hydrology
| Deepest Significant
Groundwater Contamination: |
|
75ft bgs |
| Plume Size: |
|
Plume Length: 310ft
Plume Width: 125ft
Plume Thickness: 70ft |
| Average Depth
to Groundwater: |
|
6.23ft |
Lithology and Subsurface Geology
|
|
medium-grained sand
Conductivity: 10.45ft/day
Gradient: 0.0078ft/ft
|
|
|
peat,clay, silt & very fine-grained sand
Conductivity: 0.666ft/day
|
|
|
silty, very fine-grained sand interbedded with fine-grained sand
|
|
|
sandy clay
|
|
|
clayey, fine-grained sand
|
|
|
clay, gravel, silt, sandstone and phosphate nodules
|
|
|
very stiff clay
|
Pathways and DNAPL Presence
 Groundwater
Sediments
Soil
Presumptive Evidence of DNAPL
|
Vapor Intrusion Pathway
Has the potential for vapor intrusion (VI) been evaluated? |
|
No
|
Has a vapor mitigation system been installed? |
|
|
Remediation Scenario
Cleanup
Goals: |
|
Groundwater: PCE = 3 ug/L, TCE = 3 ug/L, cis 1,2-DCE = 70 ug/L
Soil: PCE = 30 ug/kg; TCE = 30 ug/kg, cis 1,2-DCE = 400 ug/kg
|
Remedy Level: |
|
Interim Action |
Technologies
In Situ Air Sparging |
|
Why the technology was selected:
Air sparging was selected as an interim remedial measure to address contaminated groundwater in the upper surficial aquifer that was moving offsite into a drainage ditch.
Date implemented:
Air sparging was initiated on February 8, 2007.
Final remediation design:
A series of six (6) air sparge wells was installed along the southern (downgradient) property boundary to form an air sparge curtain. The sparge wells were screened 23-25 ft BLS. The system is powered by a 10 HP air compressor. The design operating rate is 70.6 cfm at 31.9 p.s.i.
Results to date:
In January 2008, the source area monitor well screened in the upper surficial aquifer produced a groundwater sample with a PCE concentration of 4,100 ug/l. The interim source removal was conducted in April of 2008 and a sample collected from the well in August found a PCE concentration of 3.9 ug/l. PCE concentrations in groundwater samples collected from that well are now non-detect.
The SVE system was shut down on January 7, 2010.
The air sparge curtain was deactivated on August 4, 2011.
PCE concentrations in groundwater samples collected from lower surficial aquifer monitor wells were as high as 1,800 ug/l during the June 2011 monitoring event.
Next Steps:
In November of 2011, six boreholes were logged to depths of from 67-74 feet BLS with a membrane interface probe to evaluate the current distribution of contaminants at the site in preparation for the design of a remedial action to address contamination in the lower surficial aquifer (portion of contaminated aquifer below the sparged zone). MIP logging confirmed that the remediation conducted to date has been successful in addressing contaminants in the upper surficial aquifer. MIP logging identified high contaminant concentrations in two zones (middle and lower surficial aquifer).
Currently remedial technologies are being evaluated to address the remaining contamination at the site. Biostimulation does not appear to be prospective given the low pH of groundwater in the lower surficial aquifer (4.2 - 4.9 standard units).
Cost to Design and Implement:
$302,700 (all technologies)
|
In Situ Soil Vapor Extraction |
|
Why the technology was selected:
Soil vapor extraction was chosen because it is an effective remedial technology for removing VOCs from permeable soils. SVE was able to address the contaminated soil beneath the facility floor slab.
Date implemented:
The soil vapor extraction system went online on July 18, 2009.
Final remediation design:
The SVE system consists of four (4) vertical vapor recovery wells screened 0.5 - 6 ft BLS. Three of these wells were installed beneath the floor slab of the drycleaning facility. The fourth well was installed outside the north wall of the facility. A passive vent well, screened 1.6 - 5.5 ft BLS was installed outside the northeast corner of the building. The SVE system is powered by 5 HP regenerative blower. Design flow rate is 75 cfm @ 5.8 inches Hg. Off gas is treated via a 100-lb. G.A.C. vessel
Results to date:
In January 2008, the source area monitor well screened in the upper surficial aquifer produced a groundwater sample with a PCE concentration of 4,100 ug/l. The interim source removal was conducted in April of 2008 and a sample collected from the well in August found a PCE concentration of 3.9 ug/l. PCE concentrations in groundwater samples collected from that well are now non-detect.
The SVE system was shut down on January 7, 2010.
The air sparge curtain was deactivated on August 4, 2011.
PCE concentrations in groundwater samples collected from lower surficial aquifer monitor wells were as high as 1,800 ug/l during the June 2011 monitoring event.
Next Steps:
In November of 2011, six boreholes were logged to depths of from 67-74 feet BLS with a membrane interface probe to evaluate the current distribution of contaminants at the site in preparation for the design of a remedial action to address contamination in the lower surficial aquifer (portion of contaminated aquifer below the sparged zone). MIP logging confirmed that the remediation conducted to date has been successful in addressing contaminants in the upper surficial aquifer. MIP logging identified high contaminant concentrations in two zones (middle and lower surficial aquifer).
Currently remedial technologies are being evaluated to address the remaining contamination at the site. Biostimulation does not appear to be prospective given the low pH of groundwater in the lower surficial aquifer (4.2 - 4.9 standard units).
Cost to Design and Implement:
$302,700 (all technologies)
|
Ex Situ Carbon Adsorption |
|
Date implemented:
The soil vapor extraction system went online on July 18, 2009.
Final remediation design:
The SVE system consists of four (4) vertical vapor recovery wells screened 0.5 - 6 ft BLS. Three of these wells were installed beneath the floor slab of the drycleaning facility. The fourth well was installed outside the north wall of the facility. A passive vent well, screened 1.6 - 5.5 ft BLS was installed outside the northeast corner of the building. The SVE system is powered by 5 HP regenerative blower. Design flow rate is 75 cfm @ 5.8 inches Hg. Off gas is treated via a 100-lb. G.A.C. vessel
Results to date:
In January 2008, the source area monitor well screened in the upper surficial aquifer produced a groundwater sample with a PCE concentration of 4,100 ug/l. The interim source removal was conducted in April of 2008 and a sample collected from the well in August found a PCE concentration of 3.9 ug/l. PCE concentrations in groundwater samples collected from that well are now non-detect.
The SVE system was shut down on January 7, 2010.
The air sparge curtain was deactivated on August 4, 2011.
PCE concentrations in groundwater samples collected from lower surficial aquifer monitor wells were as high as 1,800 ug/l during the June 2011 monitoring event.
Next Steps:
In November of 2011, six boreholes were logged to depths of from 67-74 feet BLS with a membrane interface probe to evaluate the current distribution of contaminants at the site in preparation for the design of a remedial action to address contamination in the lower surficial aquifer (portion of contaminated aquifer below the sparged zone). MIP logging confirmed that the remediation conducted to date has been successful in addressing contaminants in the upper surficial aquifer. MIP logging identified high contaminant concentrations in two zones (middle and lower surficial aquifer).
Currently remedial technologies are being evaluated to address the remaining contamination at the site. Biostimulation does not appear to be prospective given the low pH of groundwater in the lower surficial aquifer (4.2 - 4.9 standard units).
Cost to Design and Implement:
$302,700 (all technologies)
|
Ex Situ Soil Removal |
|
Why the technology was selected:
Excavation was chosen because soil contamination associated with the AST was accessible and it was important to remove as much of the contamianted organic rich soil (peat) as possible.
Date implemented:
The soil excavation was conducted in April 2008.
Final remediation design:
The interim source removal was conducted outside the northeastern corner of the building where the solvent AST was formerly located. Helical piers were installed along the perimeter of the building in the excavation area to stablize the foundation. The excavation was conducted to a depth of six (6) feet below land surface, to the water table. This included removal of the peat layer. Approximately 255 tons of contaminated soil were removed.
Results to date:
In January 2008, the source area monitor well screened in the upper surficial aquifer produced a groundwater sample with a PCE concentration of 4,100 ug/l. The interim source removal was conducted in April of 2008 and a sample collected from the well in August found a PCE concentration of 3.9 ug/l. PCE concentrations in groundwater samples collected from that well are now non-detect.
The SVE system was shut down on January 7, 2010.
The air sparge curtain was deactivated on August 4, 2011.
PCE concentrations in groundwater samples collected from lower surficial aquifer monitor wells were as high as 1,800 ug/l during the June 2011 monitoring event.
Next Steps:
In November of 2011, six boreholes were logged to depths of from 67-74 feet BLS with a membrane interface probe to evaluate the current distribution of contaminants at the site in preparation for the design of a remedial action to address contamination in the lower surficial aquifer (portion of contaminated aquifer below the sparged zone). MIP logging confirmed that the remediation conducted to date has been successful in addressing contaminants in the upper surficial aquifer. MIP logging identified high contaminant concentrations in two zones (middle and lower surficial aquifer).
Currently remedial technologies are being evaluated to address the remaining contamination at the site. Biostimulation does not appear to be prospective given the low pH of groundwater in the lower surficial aquifer (4.2 - 4.9 standard units).
Cost to Design and Implement:
$302,700 (all technologies)
|
Costs
Cost
for Assessment:
|
|
$201,300 |
Cost
for Operation and Maintenance:
|
|
$40,800 |
Total
Costs for Cleanup:
|
|
|
Lessons Learned
1. Where accessible, excavation/removal should receive serious consideration as an interim remedial measure at sites. This is particularly true where source area soils contain organic material where sorbed contaminants may continue to source groundwater contamination over a long period of time if not addressed.
2. The membrane interface probe is an excellent tool for determining contaminant mass distribution and stratigraphy in and near contaminant source areas. MIP data are invaluable in remedial design for identifying injection/treatment zones and locations and screen intervals for performance monitoring wells.
|
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
|
Site Specific References
Contamination Assessment Report: 2003
Interim Remedial Measures Plan: 2005
Remedial Action Plan SVE: 2007
Operation & Maintenance Reports: 2007 - 2010.
Groundwater Monitoring Reports: 2004 - Present
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|
