Drycleaner Site Profiles

Supreme USA Cleaners, Tamarac, Florida

Description
Historical activity that resulted in contamination.

Drycleaning using PCE was performed at this facility from June of 1995 until November of 1999. The site is located in a shopping center in a mixed retail commercial/residential setting. The contaminant source area was the area outside the service door (behind the facility) where a concrete patch had been placed over an asphalt area.

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 641 ppb
cis-1,2-Dichloroethene soil 26 ppb
1,1-Dichloroethene groundwater 4.8 ppb
Tetrachloroethene (PCE) groundwater 585 ppb
Tetrachloroethene (PCE) soil 730 ppb
Trichloroethene (TCE) groundwater 245 ppb
Trichloroethene (TCE) soil 76 ppb
trans-1,2-Dichloroethene groundwater 8.6 ppb

Site Hydrology

Deepest Significant Groundwater Contamination:   50ft bgs
Plume Size:   Plume Length: 115ft
Plume Width: 65ft
Plume Thickness: 45ft
Average Depth to Groundwater:   4.96ft

Lithology and Subsurface Geology

 
  soft, sandy limestone with limestone cobbles
Depth: 0-3.5ft bgs
3.5ft thick
Conductivity: 50ft/day
Gradient: 0.008ft/ft
 
  peat
Depth: 3.5-4ft bgs
0.5ft thick
 
  vuggy, hard limestone "caprock" with vugs and cavities filled with silt & very fine to fine-grained organic sand
Depth: 4-7ft bgs
3ft thick
 
  sandy, fossiliferous limestone
Depth: 7-14.5ft bgs
7.5ft thick
 
  fine-grained sand
Depth: 14.5-28ft bgs
13.5ft thick
 
  sandy limestone
Depth: 28-49ft bgs
21ft thick
 
  very fine to fine-grained sand
Depth: 49-52ft bgs
3ft thick
 
  sandy fossiliferous limestone
Depth: 52-101ft bgs
49ft thick

Pathways and DNAPL Presence

checkGroundwater
Sediments
checkSoil
DNAPL Present

Remediation Scenario

Cleanup Goals:
  Groundwater: PCE = 3 ug/l, TCE = 3 ug/l, cis 1,2-DCE = 70 ug/l, trans 1,2-DCE = 100 ug/l, 1,1-DCE = 7 ug/l

Soil: PCE = 30 ug/kg. TCE = 30 ug/kg, cis 1,2-DCE = 400 ug/kg, trans 1,2-DCE = 700 ug/kg

Technologies

In Situ Monitored Natural Attenuation
 

Why the technology was selected:
Monitored natural attenuation was selected as the groundwater remedy after the sharp decline in contaminant concentrations in groundwater following the excavation.

Next Steps:
A Site Rehabilitation Completion Order was issued for the site on

Cost to Design and Implement:
$35,800 for all technologies

Ex Situ Soil Removal
 

Why the technology was selected:
Removal was selected because of easy access (contaminated soil located under a paved alley) and a shallow water table.

Date implemented:
September 12 - 20, 2000

Final remediation design:
The plan was to excavate an area of 10 ft x 10 feet to the water table (approximatley 4 feet BLS) in the service alley behind the service door to the former drycleaning facility.

Results to date:
The interim remedial measure (soil excavation) was performed before the contaminaiton assessment was completed. A hard limestone (caprock) was encountered below the peat which precluded deeper excavation. The caprock surface was undulating which permitted deeper excavation in some areas. The excavation area was expanded twice based on confirmatory soil sampling. The final area of excavation was approximatley 20 feet x 25 feet to an average depth of 4 feet. When the excavation was expanded the first two roll-offs of excavated soil had to be removed before proceeding with additional excavation because there was not enough room to state additional roll-offs. Approximately 74 yards of contaminated soil was excavated (approximately 96.7 tons), removed from the site and disposed of as non-hazardous. The excavation was backfilled and repaved. SPLP leachate extracted from confirmatory soil samples showed that remaining contaminant concentrations in soils were not at levels that would continue to act as a source for groundwater contamination. Contaminant concentrations in groundwater showed significant decreases after the excavation and groundwater monitoring was completed in September of 2003, three years after the excavation.

Next Steps:
A Site Rehabilitation Completion Order was issued for the site on

Cost to Design and Implement:
$35,800 for all technologies

Costs

Cost for Assessment:
  $126,800
Cost for Operation and Maintenance:
  Monitoring: $9,800 Site Restoration: $4,700
Total Costs for Cleanup:
  $177,000

Lessons Learned

1. Use of an onsite mobile laboratory to analyze soil samples during the excavation saved time and money.

2. The bulk of the PCE mass at the site was sorbed onto the peat layer which occured at or near the water table. This zone was sourceing the groundwater contamination and once it was removed, contaminant concentrations declined rapidly.

3. in hindsight, conducting a few additional shallow borings in the projected excavation area to determine lateral variations in lithology would have been useful to anticpate excavation problems.

4. Conducting the excavation before the site assessment was completed resulted in a timely closure for the site.

Contacts

Nancy Murchison, Project Manager
Bureau of Waste Cleanup (MS4520)
Florida Department of Environmental Protection
2600 Blair Stone Road
Tallahassee, Florida 32399-2400
Phone: (850) 245-8990
E-mail: Nancy Murchison@dep.state.fl.us

Gregg Roberts, PG
Shaw Environmental, Inc.
725 U.S. Highway 301 South
Tampa, Florida 33619-3439
Phone (3180 612-3687
gregg.roberts@shawgrp.com


Site Specific References

Site Assessment Report - May 2001

Interim Source Removal Report - December 2000

Groundwater Monitoring Reports 2002 - 2003