Drycleaner Site Profiles

Sta Brite Cleaners II, Sarasota, Florida

Description
Historical activity that resulted in contamination.

Drycleaning was performed at this site from March 1995 until late 2005. PCE was used during the first three years of operations, and then the facility switched to petroleum solvent. There was a reported PCE discharge in 1995 during a filter change. The contaminant source area at the site is the soil beneath the facility floor slab under and in the near vicinity of the former location of the drycleaning machine.

Remediation Status: Site closed


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


Contaminant Media Concentration (ppb) Nondetect
cis-1,2-Dichloroethene groundwater 469 ppb
cis-1,2-Dichloroethene soil 9.7 ppb
Tetrachloroethene (PCE) groundwater 164 ppb
Tetrachloroethene (PCE) soil 14,700 ppb
Trichloroethene (TCE) groundwater 405 ppb
Trichloroethene (TCE) soil 72.5 ppb
trans-1,2-Dichloroethene groundwater 16 ppb
trans-1,2-Dichloroethene soil 1.1 ppb

Site Hydrology

Deepest Significant Groundwater Contamination:   15ft bgs
Plume Size:   Plume Length: 70ft
Plume Width: 30ft
Plume Thickness: 15ft
Average Depth to Groundwater:   4ft

Lithology and Subsurface Geology

 
  Fine to medium-grained sand, slightly clayey
Depth: 0-13ft bgs
13ft thick
Conductivity: 0.021ft/day
Gradient: 0.002ft/ft
 
  Fine to coarse-grained sand with thin limestone lenses
Depth: 13-24ft bgs
11ft thick
 
  Fossiliferous limestone interbedded with silty clay
Depth: 24-38.5ft bgs
14.5ft thick
 
  Clayey silt
Depth: 38.5-43ft bgs
4.5ft thick
 
  Clayey fossiliferous limestone
Depth: 43-61ft bgs
18ft 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):
  Soil Vapor Extraction

Remediation Scenario

Cleanup Goals:
  Soil: PCE = 30 µg/kg

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

Technologies

In Situ Bioremediation
 

Why the technology was selected:
In-situ bioremediation was selected because aquifer conditions are anaerobic (dissolved oxygen concentrations in groundwater ranged from 0.3 to 0.7 mg/L) and reductive dechlorination was occurring (TCE and cis 1,2-DCE were present in groundwater).

Date implemented:
Potassium Lactate Injection: August 2004

Final remediation design:
In-Situ Bioremediation: Two one-inch-diameter Schedule 40 PVC injection wells (screened 2-12 ft bgs) were installed using a direct push rig. A total of 500 lbs. of 60% potassium lactate, diluted with approximately 2000 gallons of water, were injected in the wells at 15 PSI, a rate of approximately 0.75 gpm. The injection wells were then flushed with 400 gallons of water, with 6.5 grams of sodium thiosulfate added to flush any residual potassium lactate from the injection wells that could result in biofouling.

Results to date:
The SVE system operated from September 6, 2000 until July 25, 2001. An estimated 3 lbs. of VOCs were recoved. Confirmatory soil sampling did not detect any contaminants in soils in concentrations exceeding cleanup target levels for leachability. Continued groundwater monitoring showed a rebound in contaminant concentrations (PCE and TCE were detected in concentrations as high as 5.8, and 18.6 µg/L, respectively, in two monitor wells located in the contaminant source area. At that time, the decision was made to inject potassium lactate to "polish" contaminated groundwater at the site. The potassium lactate injection resulted in a reduction of contaminant concentrations in groundwater below cleanup target levels.

Next Steps:
The site has met the No Further Action criteria, and a Site Rehabilitation Completion Order will be issued.

Cost to Design and Implement:
$102,400 for all technologies

In Situ Soil Vapor Extraction
 

Why the technology was selected:
SVE was selected because it is an effective technology for removing VOCs from unsaturated permeable sediments (fine to medium-grained sand at this site).

Date implemented:
SVE: September 2000

Final remediation design:
SVE System: A 5-foot lateral vapor extraction well was installed at a depth of 3 ft bgs, just outside the wall opposite the location of the drycleaning machine. The lateral was constructed of 4-inch-diameter Schedule 40 PVC with 0.02-inch slot. The system was powered by a 3-HP rotary lobe blower. A 55-gallon moisture separtor was utilized, and vapors were treated with two 175-lb. G.A.C. units.

Results to date:
The SVE system operated from September 6, 2000 until July 25, 2001. An estimated 3 lbs. of VOCs were recoved. Confirmatory soil sampling did not detect any contaminants in soils in concentrations exceeding cleanup target levels for leachability. Continued groundwater monitoring showed a rebound in contaminant concentrations (PCE and TCE were detected in concentrations as high as 5.8, and 18.6 µg/L, respectively, in two monitor wells located in the contaminant source area. At that time, the decision was made to inject potassium lactate to "polish" contaminated groundwater at the site. The potassium lactate injection resulted in a reduction of contaminant concentrations in groundwater below cleanup target levels.

Next Steps:
The site has met the No Further Action criteria, and a Site Rehabilitation Completion Order will be issued.

Cost to Design and Implement:
$102,400 for all technologies

Ex Situ Carbon Adsorption
 

Date implemented:
SVE: September 2000

Final remediation design:
SVE System: A 5-foot lateral vapor extraction well was installed at a depth of 3 ft bgs, just outside the wall opposite the location of the drycleaning machine. The lateral was constructed of 4-inch-diameter Schedule 40 PVC with 0.02-inch slot. The system was powered by a 3-HP rotary lobe blower. A 55-gallon moisture separtor was utilized, and vapors were treated with two 175-lb. G.A.C. units.

Next Steps:
The site has met the No Further Action criteria, and a Site Rehabilitation Completion Order will be issued.

Cost to Design and Implement:
$102,400 for all technologies

Costs

Cost for Assessment:
  $87,200
Cost for Operation and Maintenance:
  $69,500 (includes monitoring) $ 5,000 (site restoration)
Total Costs for Cleanup:
  $264,100

Lessons Learned

1. This site probably could have been remediated by soil vacuum extraction only had it not been for a seasonally high water table (to less than 2 feet bgs).

2. Small diameter PVC wells (microwells) can be utilized as injection wells to deliver relatively small volumes of injectants into permeable sediments.

3. "Biopolishing", the introduction of a small amount of a carbon source into groundwater, where conditions are favorable for reductive dechlorination can be an effective, low-cost method for remediating sites with low levels of contaminants.

4. The alternative to injecting potassium lactate would have been monitored natural attenuation that could have continued for a number of years.

Contacts

Karen Milicic, Project Manager
Bureau of Waste Cleanup (MS4520)
Florida DEP
2600 Blair Stone Road
Tallahassee, Florida 32399-2400
Phone: (850) 245-8931
E-mail: Karen.Milicic@dep.state.fl.us

Mike Lodato, PG - Consultant
GeoSyntec Consultants
14055 Riveredge Drive, Suite 300
Tampa, Florida 33637
Phone: (813) 558 9829
E-mail: mLodato@Geosyntec.com

Site Specific References

Site Assessment Report - November 1999
Remedial Action Plan - May 2000
Limited Remedial Action Plan (lactate injection): June 2004
Groundwater Monitoring Reports