Drycleaner Site Profiles

Village Green Shopping Center, Rockledge, Florida

Description
Historical activity that resulted in contamination.

This is a designated state Brownsfield site. PCE drycleaning operations took place in a bay in this shopping center during the 1960s and 1970s. PCE was found in groundwater samples collected as part of a Phase II Environmental Site Assessment. The site is located in a mixed retail commercial/residential setting. The contaminant source area is located beneath the floor slab of the bay that formerly housed the drycleaning operation.

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


Contaminant Media Concentration (ppb) Nondetect
cis-1,2-Dichloroethene groundwater 8,550 ppb
Tetrachloroethene (PCE) groundwater 27,300 ppb
Tetrachloroethene (PCE) soil 564,000 ppb
Trichloroethene (TCE) groundwater 7,900 ppb
Trichloroethene (TCE) soil 5,007 ppb
Vinyl Chloride groundwater 780 ppb

Site Hydrology

Deepest Significant Groundwater Contamination:   45ft bgs
Plume Size:   Plume Length: 330ft
Plume Width: 140ft
Average Depth to Groundwater:   4ft

Lithology and Subsurface Geology

 
  fine-grained sand
Depth: 0-9ft bgs
9ft thick
Conductivity: 5ft/day
Gradient: 0.003ft/ft
 
  silty fine-grained sand with organics (Foc of 1.1%)
Depth: 9-12ft bgs
3ft thick
Conductivity: 5ft/day
 
  fine-grained sand with shells
Depth: 12-45ft bgs
33ft thick
Conductivity: 8ft/day
 
  silty sand with clay
Depth: 45ft bgs

Pathways and DNAPL Presence

checkGroundwater
Sediments
checkSoil
checkDNAPL Present

Vapor Intrusion Pathway

Has the potential for vapor intrusion (VI) been evaluated?
  Unknown
Has a vapor mitigation system been installed?
  Yes 
Type of Vapor Mitigation System(s):
  Other
Additional VI Information:
  Multi-Phase extraction system was installed and operated.

Remediation Scenario

Cleanup Goals:
  Groundwater: PCE = 3.0 ug/L; TCE = 3.0 ug/L; cis 1,2-DCE = 70 ug/L

Soil (leachability): PCE = 30 ug/Kg; TCE = 30 ug/Kg

Technologies

In Situ Bioremediation
 

Why the technology was selected:
The contaminant source area was located beneath the building and excavation was not an option. The predominant portion of the contaminant mass resided in an organic-rich silty sand in the shallow portion of the aquifer. Ethyl lactate is a relatively cheap carbon source. The remedial goals were to reduce the sorbed contaminant mass, reduce the dissolved VOC flux and enable monitored natural attenuation. PCE daughter products were present, indicating that reductive dechlorination was occurring in the aquifer.

Date implemented:
Ethyl lactate flushing occurred from November 12, 2002 to February 13, 2003.

Final remediation design:
In the contaminant source area, 12 co-solvent flushing points were installed and screened from 6-8 ft BGS. Seven extraction wells (screened 12-16 ft BGS) were installed. In the dissolved phase portion of the plume 4 shallow injection wells were installed (screened 5-15 ft BLS) and five deep injection wells (screened 35-45 ft BGS) were installed. The plan was to inject a 100% ethyl lactate solution in the shallow soure zone (organic-rich sand). The co-solvent flush system consisted of a 25 hp PreVac MPE system, two 21,000 gallon frac tanks, a 24-inch diameter by 25 ft. air stripper with an AF-12 5 hp blower and an off-gas carbon treatment unit (600 lb. GAC). The MPE system operated at a vacuum of 18 to 21 inches of mercury (extraction from 7 source area wells) and corresponding air flow rate of approximately 100 cfm. The system was operated in batches: frac tank filled, cycled through air stripper and discharged to second frac tank for confirmatory sampling. Treated effluent (containing residual ethyl lactate) was pumped into injection wells or a percolation area.

Results to date:
A total of 880 gallons of ethyl lactate was pumped into 12 injection points above the organic-rich shallow sand (source area). Fluids were extracted from 7 recovery wells screened below the source area and the extracted fluids were pumped to 20,000 gallon frac tanks and circulated through the air stripper. There was a focused injection of 200 gallons of ethyl lactate. A total of 131,000 gallons of groundwater was extracted/treated/injected and or percolated. The site is currently in natural attenuation monitoring with seimi-annual dilute ethyl lactate dosing. A spike of PCE was detected in the influent as a result of the initial injection event and a smaller PCE spike was detected following the focused injection event. Confirmatory soil sampling revealed that maximum PCE contaminant concentrations in soil decreased from 564,000 ug/kg to 2,300 ug/kg. An initial increase in PCE daughter products was observed in groundwater. One year after injection, dissolved PCE concentrations in groundwater in the source area had decreased by 68%. PCE daugher product concentrations have have shown a continuing decreasing trend after the initial increase in concentrations. In the downgradient portion of the plume, there has been a > 99% decrease in PCE concentrations in groundwater samples collected from the wells that previously had the highest contaminant concentrations. Concentrations of PCE daugher products in groundwater have shown strong declines after initial increases in concentrations.

Next Steps:
Continued semi-annual monitoring and semi-annual dilute ethyl lactate dosing. Consideration is being given to bioaugmentation of the source area with KB-1(TM).

In Situ Multi Phase Extraction
 

Why the technology was selected:
The contaminant source area was located beneath the building and excavation was not an option. The predominant portion of the contaminant mass resided in an organic-rich silty sand in the shallow portion of the aquifer. Ethyl lactate is a relatively cheap carbon source. The remedial goals were to reduce the sorbed contaminant mass, reduce the dissolved VOC flux and enable monitored natural attenuation. PCE daughter products were present, indicating that reductive dechlorination was occurring in the aquifer.

Date implemented:
Ethyl lactate flushing occurred from November 12, 2002 to February 13, 2003.

Final remediation design:
In the contaminant source area, 12 co-solvent flushing points were installed and screened from 6-8 ft BGS. Seven extraction wells (screened 12-16 ft BGS) were installed. In the dissolved phase portion of the plume 4 shallow injection wells were installed (screened 5-15 ft BLS) and five deep injection wells (screened 35-45 ft BGS) were installed. The plan was to inject a 100% ethyl lactate solution in the shallow soure zone (organic-rich sand). The co-solvent flush system consisted of a 25 hp PreVac MPE system, two 21,000 gallon frac tanks, a 24-inch diameter by 25 ft. air stripper with an AF-12 5 hp blower and an off-gas carbon treatment unit (600 lb. GAC). The MPE system operated at a vacuum of 18 to 21 inches of mercury (extraction from 7 source area wells) and corresponding air flow rate of approximately 100 cfm. The system was operated in batches: frac tank filled, cycled through air stripper and discharged to second frac tank for confirmatory sampling. Treated effluent (containing residual ethyl lactate) was pumped into injection wells or a percolation area.

Results to date:
A total of 880 gallons of ethyl lactate was pumped into 12 injection points above the organic-rich shallow sand (source area). Fluids were extracted from 7 recovery wells screened below the source area and the extracted fluids were pumped to 20,000 gallon frac tanks and circulated through the air stripper. There was a focused injection of 200 gallons of ethyl lactate. A total of 131,000 gallons of groundwater was extracted/treated/injected and or percolated. The site is currently in natural attenuation monitoring with seimi-annual dilute ethyl lactate dosing. A spike of PCE was detected in the influent as a result of the initial injection event and a smaller PCE spike was detected following the focused injection event. Confirmatory soil sampling revealed that maximum PCE contaminant concentrations in soil decreased from 564,000 ug/kg to 2,300 ug/kg. An initial increase in PCE daughter products was observed in groundwater. One year after injection, dissolved PCE concentrations in groundwater in the source area had decreased by 68%. PCE daugher product concentrations have have shown a continuing decreasing trend after the initial increase in concentrations. In the downgradient portion of the plume, there has been a > 99% decrease in PCE concentrations in groundwater samples collected from the wells that previously had the highest contaminant concentrations. Concentrations of PCE daugher products in groundwater have shown strong declines after initial increases in concentrations.

Next Steps:
Continued semi-annual monitoring and semi-annual dilute ethyl lactate dosing. Consideration is being given to bioaugmentation of the source area with KB-1(TM).

Ex Situ Air Stripping
 

Why the technology was selected:
The contaminant source area was located beneath the building and excavation was not an option. The predominant portion of the contaminant mass resided in an organic-rich silty sand in the shallow portion of the aquifer. Ethyl lactate is a relatively cheap carbon source. The remedial goals were to reduce the sorbed contaminant mass, reduce the dissolved VOC flux and enable monitored natural attenuation. PCE daughter products were present, indicating that reductive dechlorination was occurring in the aquifer.

Date implemented:
Ethyl lactate flushing occurred from November 12, 2002 to February 13, 2003.

Final remediation design:
In the contaminant source area, 12 co-solvent flushing points were installed and screened from 6-8 ft BGS. Seven extraction wells (screened 12-16 ft BGS) were installed. In the dissolved phase portion of the plume 4 shallow injection wells were installed (screened 5-15 ft BLS) and five deep injection wells (screened 35-45 ft BGS) were installed. The plan was to inject a 100% ethyl lactate solution in the shallow soure zone (organic-rich sand). The co-solvent flush system consisted of a 25 hp PreVac MPE system, two 21,000 gallon frac tanks, a 24-inch diameter by 25 ft. air stripper with an AF-12 5 hp blower and an off-gas carbon treatment unit (600 lb. GAC). The MPE system operated at a vacuum of 18 to 21 inches of mercury (extraction from 7 source area wells) and corresponding air flow rate of approximately 100 cfm. The system was operated in batches: frac tank filled, cycled through air stripper and discharged to second frac tank for confirmatory sampling. Treated effluent (containing residual ethyl lactate) was pumped into injection wells or a percolation area.

Results to date:
A total of 880 gallons of ethyl lactate was pumped into 12 injection points above the organic-rich shallow sand (source area). Fluids were extracted from 7 recovery wells screened below the source area and the extracted fluids were pumped to 20,000 gallon frac tanks and circulated through the air stripper. There was a focused injection of 200 gallons of ethyl lactate. A total of 131,000 gallons of groundwater was extracted/treated/injected and or percolated. The site is currently in natural attenuation monitoring with seimi-annual dilute ethyl lactate dosing. A spike of PCE was detected in the influent as a result of the initial injection event and a smaller PCE spike was detected following the focused injection event. Confirmatory soil sampling revealed that maximum PCE contaminant concentrations in soil decreased from 564,000 ug/kg to 2,300 ug/kg. An initial increase in PCE daughter products was observed in groundwater. One year after injection, dissolved PCE concentrations in groundwater in the source area had decreased by 68%. PCE daugher product concentrations have have shown a continuing decreasing trend after the initial increase in concentrations. In the downgradient portion of the plume, there has been a > 99% decrease in PCE concentrations in groundwater samples collected from the wells that previously had the highest contaminant concentrations. Concentrations of PCE daugher products in groundwater have shown strong declines after initial increases in concentrations.

Next Steps:
Continued semi-annual monitoring and semi-annual dilute ethyl lactate dosing. Consideration is being given to bioaugmentation of the source area with KB-1(TM).

Ex Situ Bioremediation
 

Why the technology was selected:
The contaminant source area was located beneath the building and excavation was not an option. The predominant portion of the contaminant mass resided in an organic-rich silty sand in the shallow portion of the aquifer. Ethyl lactate is a relatively cheap carbon source. The remedial goals were to reduce the sorbed contaminant mass, reduce the dissolved VOC flux and enable monitored natural attenuation. PCE daughter products were present, indicating that reductive dechlorination was occurring in the aquifer.

Date implemented:
Ethyl lactate flushing occurred from November 12, 2002 to February 13, 2003.

Final remediation design:
In the contaminant source area, 12 co-solvent flushing points were installed and screened from 6-8 ft BGS. Seven extraction wells (screened 12-16 ft BGS) were installed. In the dissolved phase portion of the plume 4 shallow injection wells were installed (screened 5-15 ft BLS) and five deep injection wells (screened 35-45 ft BGS) were installed. The plan was to inject a 100% ethyl lactate solution in the shallow soure zone (organic-rich sand). The co-solvent flush system consisted of a 25 hp PreVac MPE system, two 21,000 gallon frac tanks, a 24-inch diameter by 25 ft. air stripper with an AF-12 5 hp blower and an off-gas carbon treatment unit (600 lb. GAC). The MPE system operated at a vacuum of 18 to 21 inches of mercury (extraction from 7 source area wells) and corresponding air flow rate of approximately 100 cfm. The system was operated in batches: frac tank filled, cycled through air stripper and discharged to second frac tank for confirmatory sampling. Treated effluent (containing residual ethyl lactate) was pumped into injection wells or a percolation area.

Results to date:
A total of 880 gallons of ethyl lactate was pumped into 12 injection points above the organic-rich shallow sand (source area). Fluids were extracted from 7 recovery wells screened below the source area and the extracted fluids were pumped to 20,000 gallon frac tanks and circulated through the air stripper. There was a focused injection of 200 gallons of ethyl lactate. A total of 131,000 gallons of groundwater was extracted/treated/injected and or percolated. The site is currently in natural attenuation monitoring with seimi-annual dilute ethyl lactate dosing. A spike of PCE was detected in the influent as a result of the initial injection event and a smaller PCE spike was detected following the focused injection event. Confirmatory soil sampling revealed that maximum PCE contaminant concentrations in soil decreased from 564,000 ug/kg to 2,300 ug/kg. An initial increase in PCE daughter products was observed in groundwater. One year after injection, dissolved PCE concentrations in groundwater in the source area had decreased by 68%. PCE daugher product concentrations have have shown a continuing decreasing trend after the initial increase in concentrations. In the downgradient portion of the plume, there has been a > 99% decrease in PCE concentrations in groundwater samples collected from the wells that previously had the highest contaminant concentrations. Concentrations of PCE daugher products in groundwater have shown strong declines after initial increases in concentrations.

Next Steps:
Continued semi-annual monitoring and semi-annual dilute ethyl lactate dosing. Consideration is being given to bioaugmentation of the source area with KB-1(TM).

Ex Situ Carbon Adsorption
 

Why the technology was selected:
The contaminant source area was located beneath the building and excavation was not an option. The predominant portion of the contaminant mass resided in an organic-rich silty sand in the shallow portion of the aquifer. Ethyl lactate is a relatively cheap carbon source. The remedial goals were to reduce the sorbed contaminant mass, reduce the dissolved VOC flux and enable monitored natural attenuation. PCE daughter products were present, indicating that reductive dechlorination was occurring in the aquifer.

Date implemented:
Ethyl lactate flushing occurred from November 12, 2002 to February 13, 2003.

Final remediation design:
In the contaminant source area, 12 co-solvent flushing points were installed and screened from 6-8 ft BGS. Seven extraction wells (screened 12-16 ft BGS) were installed. In the dissolved phase portion of the plume 4 shallow injection wells were installed (screened 5-15 ft BLS) and five deep injection wells (screened 35-45 ft BGS) were installed. The plan was to inject a 100% ethyl lactate solution in the shallow soure zone (organic-rich sand). The co-solvent flush system consisted of a 25 hp PreVac MPE system, two 21,000 gallon frac tanks, a 24-inch diameter by 25 ft. air stripper with an AF-12 5 hp blower and an off-gas carbon treatment unit (600 lb. GAC). The MPE system operated at a vacuum of 18 to 21 inches of mercury (extraction from 7 source area wells) and corresponding air flow rate of approximately 100 cfm. The system was operated in batches: frac tank filled, cycled through air stripper and discharged to second frac tank for confirmatory sampling. Treated effluent (containing residual ethyl lactate) was pumped into injection wells or a percolation area.

Results to date:
A total of 880 gallons of ethyl lactate was pumped into 12 injection points above the organic-rich shallow sand (source area). Fluids were extracted from 7 recovery wells screened below the source area and the extracted fluids were pumped to 20,000 gallon frac tanks and circulated through the air stripper. There was a focused injection of 200 gallons of ethyl lactate. A total of 131,000 gallons of groundwater was extracted/treated/injected and or percolated. The site is currently in natural attenuation monitoring with seimi-annual dilute ethyl lactate dosing. A spike of PCE was detected in the influent as a result of the initial injection event and a smaller PCE spike was detected following the focused injection event. Confirmatory soil sampling revealed that maximum PCE contaminant concentrations in soil decreased from 564,000 ug/kg to 2,300 ug/kg. An initial increase in PCE daughter products was observed in groundwater. One year after injection, dissolved PCE concentrations in groundwater in the source area had decreased by 68%. PCE daugher product concentrations have have shown a continuing decreasing trend after the initial increase in concentrations. In the downgradient portion of the plume, there has been a > 99% decrease in PCE concentrations in groundwater samples collected from the wells that previously had the highest contaminant concentrations. Concentrations of PCE daugher products in groundwater have shown strong declines after initial increases in concentrations.

Next Steps:
Continued semi-annual monitoring and semi-annual dilute ethyl lactate dosing. Consideration is being given to bioaugmentation of the source area with KB-1(TM).

Costs

Cost for Assessment:
  No cost data were available.
Cost for Operation and Maintenance:
 
Total Costs for Cleanup:
 

Lessons Learned

1.This appears to be an effective remedy for solubilizing sorbed contaminant mass.

2. The remedial system provides an effective dual purpose application - source removal and enhanced biormediation.

3. Implementation costs are similar to excavation and/or chemical oxidation.

4. Follow-up monitoring/dosing costs are low compared to operating a mechanical system.

5. Technology is flexible and can be followed by bioaugmentation.

Contacts

Jim Langenbach, P.E.
GeoSyntec Consultants
6770 South Washington Avenue, Suite 1
Titusville, Florida 32780