Drycleaner Site Profiles

Asian Cleaners, Sanford, Florida

Description
Historical activity that resulted in contamination.

This is an active PCE drycleaning facility that has been in operation since 1984. The facility is located in a strip mall in a mixed commercial/residential setting, approximately 150 feet northeast of a 40-acre lake. The nearest public water supply well is located approximately 2,500 feet north of the facility. The contaminant source areas identified at the drycleaners include the soils beneath the building floor slab in the vicinity of the drycleaning machine and the area outside the service door. Two petroleum contaminated sites (service stations) are located approximately 700 feet hydraulically upgradient of the facility. One of these sites is under active remediation.

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 soil 1 ppb
cis-1,2-Dichloroethene soil 1 ppb
Tetrachloroethene (PCE) soil 1 ppb
Tetrachloroethene (PCE) soil 1 ppb
Trichloroethene (TCE) soil 1 ppb
Trichloroethene (TCE) soil 1 ppb
Vinyl Chloride soil 1 ppb
Vinyl Chloride soil 1 ppb
soil 1 ppb
soil 1 ppb
soil 1 ppb

Site Hydrology

Deepest Significant Groundwater Contamination:   16ft bgs
Plume Size:   Plume Length: 125ft
Plume Width: 35ft
Plume Thickness: 13ft
Average Depth to Groundwater:   3ft

Lithology and Subsurface Geology

 
  fine-grained silty sands with some clay interbeds
Depth: 0-48ft bgs
48ft thick
Conductivity: 1.5ft/day
Gradient: 0.025ft/ft
 
  sandy clay with silt and shell fragments
Depth: 48-53ft bgs
5ft thick
 
  fine-grained sand
Depth: 53-59ft bgs
6ft thick

Pathways and DNAPL Presence

checkGroundwater
Sediments
checkSoil
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:
  Groundwater (MCLs): PCE = 3.0 µg/l; TCE = 3.0 µg/l; cis 1,2-DCE = 70 µg/l; trans 1,2-DCE = 100 µg/l; vinyl chloride = 1.0 µg/l;
Soil (Cleanup target leachability standard): PCE = 30 µg/kg; TCE = 30 µg/kg; cis 1,2-DCE = 400 µg/kg; vinyl chloride = 7 µg/kg
Remedy Level:
  Full Scale Remedy

Technologies

in Situ Air Sparging
 

Why the technology was selected:
Since reductive dechlorination is actively occurring in groundwater at the site, the introduction of nutrients (enhanced biosparging or EBS) should enhance contaminant degradation.

Date implemented:
enhanced biosparging - January 11, 2002.

Final remediation design:
Biosparging System - Four biosparing wells were installed utilizing a direct push rig - one slant well (installed beneath the drycleaning facility) and three vertical wells. Well screens are constructed of stainless steel and risers are black iron pipe. At the completion of the triethylphosphate/nitrous oxide treatment regime, propane may be added approximately 6 hours biweekly to improve the microbe concentration.

Biosparge wells: screened 33-35 ft bgs
System design radius of influence: 25-30 ft
Design injection flow rate: 3-5 scf/m per well (12-20 scf/m total flow rate)
Actual injection rate: 1 scf/m per well, sparging from two wells at a time in one-hour intervals twice per day to allow aquifer stabilization between injections.
Injection concentrations/mass (for project life): nitrous oxide, 0.07% - 0.1% by volume in air (1060 lbs total mass); triehtylphosphate, 0.007% by volume in air (106 lab total mass); oxygen (as air), 3-5 scf/m per well at 15 psig (1,060,000 lbs total mass); propane, 50% of lower explosive limit in air, 6 hours biweekly at end of treatment regime (10 lbs total mass)

Water from the air/water separator is discharged to an infiltration trench located in the radius of influence of both the SVE and EBS systems so that any water extracted will be retreated by the biosparge system.

Other technologies used:
Enhanced Biosparging (PHOSters/Magnus)

Results to date:
The biosparge system was operated from January-November 2002; July 2003-March 2004 and then from April 2005-March 2006. Contaminant rebound occurred after each shut down period. The SVE system was shut down on July 13, 2006. Confirmatory soil sampling showed that contaminated soil has been effectively remediated.

Vinyl chloride is the only contaminant in groundwater in concentrations exceeding MCLs. During the most recent monitoring event, vinyl chloride concentraitons were as high as 38 ug/l. Contamination is limited to the very top (upper 5 feet) of the water table.

Next Steps:
Monitored natural attenuation

Cost to Design and Implement:
Design $32,000
Implementation: $118,000 for for all technologies together

in Situ Soil Vapor Extraction
 

Why the technology was selected:
Since reductive dechlorination is actively occurring in groundwater at the site, the introduction of nutrients (enhanced biosparging or EBS) should enhance contaminant degradation.

Date implemented:
enhanced biosparging - January 11, 2002.

Final remediation design:
Biosparging System - Four biosparing wells were installed utilizing a direct push rig - one slant well (installed beneath the drycleaning facility) and three vertical wells. Well screens are constructed of stainless steel and risers are black iron pipe. At the completion of the triethylphosphate/nitrous oxide treatment regime, propane may be added approximately 6 hours biweekly to improve the microbe concentration.

Biosparge wells: screened 33-35 ft bgs
System design radius of influence: 25-30 ft
Design injection flow rate: 3-5 scf/m per well (12-20 scf/m total flow rate)
Actual injection rate: 1 scf/m per well, sparging from two wells at a time in one-hour intervals twice per day to allow aquifer stabilization between injections.
Injection concentrations/mass (for project life): nitrous oxide, 0.07% - 0.1% by volume in air (1060 lbs total mass); triehtylphosphate, 0.007% by volume in air (106 lab total mass); oxygen (as air), 3-5 scf/m per well at 15 psig (1,060,000 lbs total mass); propane, 50% of lower explosive limit in air, 6 hours biweekly at end of treatment regime (10 lbs total mass)

Water from the air/water separator is discharged to an infiltration trench located in the radius of influence of both the SVE and EBS systems so that any water extracted will be retreated by the biosparge system.

Results to date:
The biosparge system was operated from January-November 2002; July 2003-March 2004 and then from April 2005-March 2006. Contaminant rebound occurred after each shut down period. The SVE system was shut down on July 13, 2006. Confirmatory soil sampling showed that contaminated soil has been effectively remediated.

Vinyl chloride is the only contaminant in groundwater in concentrations exceeding MCLs. During the most recent monitoring event, vinyl chloride concentraitons were as high as 38 ug/l. Contamination is limited to the very top (upper 5 feet) of the water table.

Next Steps:
Monitored natural attenuation

Cost to Design and Implement:
Design $32,000
Implementation: $118,000 for for all technologies together

in Situ Soil Vapor Extraction
 

Why the technology was selected:
SVE is a cost-effective technology for removing VOCs from permeable unsaturated soils.

Date implemented:
SVE - January 9, 2002

Final remediation design:
A horizontal vapor extraction well was installed because of the shallow depth of groundwater at the site. The SVE lateral was installed just outside the service door of the facility. The SVE lateral is piped to a portable trailer-mounted treatment system.

Extraction well: 1- 20 ft. screened section of 4-inch PVC
Depth: 2 ft bgs
SVE motor size: 5 hp Rotron 707F72MXL blower.
Design flowrate: 34 scf/m at design vacuum of 49 in. w.c.
Operational flowrate: 50.5 to 103 scf/m
Design radius of influence: 16 ft
Emissions treatment: 2-200 lb GAC canisters in series.

Results to date:
The SVE system was modified to include the addition of a large diameter vapor extraction well installed beneath the facility floor slab. Soil was excated beneath the faciliyt floor slab (an area 3 ft x 3 ft x 2 1/2 feet deep). A 55-gallon polyethylene drum with 0.06 to 0.010 inch slots was placed in an excavation and the annulus was lined with 1/4 to 1/2-inch diameter river rock. Operational flow rate for the large diameter well was 20.7 scfm with 30 inches w.c. The calcuated radius of influence for this well was 27.4 feet. The modified SVE system including the large diameter well and the original lateral vapor extraction well went online on April 25, 2003.

Vinyl chloride is the only contaminant in groundwater in concentrations exceeding MCLs. During the most recent monitoring event, vinyl chloride concentraitons were as high as 38 ug/l. Contamination is limited to the very top (upper 5 feet) of the water table.

Next Steps:
Monitored natural attenuation

Cost to Design and Implement:
Design $32,000
Implementation: $118,000 for for all technologies together

Costs

Cost for Assessment:
  $88,600
Cost for Operation and Maintenance:
  $150,000 (estimated for 12 months operation)
Total Costs for Cleanup:
 

Lessons Learned

1. Biosparge wells needed to be cycled (on/off) to allow for aquifer stabilization, minimization of groundwater mounding and to eliminate the potential for contaminant volatilization.

2. SVE radius of influence has been reduced by water intake into system transfer lines. Also, SVE lateral well was installed outside the back wall of the building. Given the shallow depth to water and the presence of the builidng footer the system was not able to influence the contamination under the building floor slab near the drycleaning machine. This made the installation of the large diameter vapor extraction well necessary. Large diameter vapor extraction wells are effecitve at sites with shallow water tables.

3. Direct push installation of a slant sparge well beneath the drycleaning facility allowed for treatment of the primary contaminant source area at the site.

4. Clay lenses are likely responsible for the failure of the sparge system to remediate contaminants in groundwater.

5. In retrospect, biosparging was not a good choice to remediate this site. Groundwater contaminants were predominantly PCE daughter products (Cis 1,2-DCE and vinyl chloride). The nutrients utilized in the Phoster process do not appear to have enhanced degradation appreciably.

Contacts

Christopher Pellegrino, Project Manager
Florida Dept. of Environmental Protection
Bureau of Waste Cleanup, MS 4520
2600 Blair Stone Road
Tallahassee, Florida 32399-2400
(850) 245-8972
Christopher.pellegrino@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

1. Contamination Assessment Report - 7/99
2. Remedial Action Plan - 5/01
3. Construction Completion Report - 2/02
4. O&M/monitoring reports: 2002 - 2007