Drycleaner Site Profiles

A Dry Cleaner in Warwick, RI, Warwick, Rhode Island

Description
Historical activity that resulted in contamination.

The dry cleaner is located within a strip mall in Warwick, Rhode Island. Apparently PCE was historically released to the subsurface in the general vicinity of the back door.

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


Contaminant Media Concentration (ppb) Nondetect
Tetrachloroethene (PCE) groundwater 71 ppb

Site Hydrology

Deepest Significant Groundwater Contamination:   64ft bgs
Plume Size:  
Average Depth to Groundwater:   23ft

Lithology and Subsurface Geology

 
  fine to medium sand with gravel and cobble. A large percent of the sand fraction is fine grained.
Depth: 0-64ft bgs
64ft thick
Conductivity: 20ft/day
Gradient: 0.02ft/ft
 
  granite bedrock
Depth: 64ft bgs

Pathways and DNAPL Presence

checkGroundwater
Sediments
Soil
DNAPL Present

Remediation Scenario

Cleanup Goals:
  Groundwater: PCE, 5 µg/L

Technologies

In Situ In-Well Air Stripping
 

Why the technology was selected:
The aquifer is interconnected and relatively permeable, allowing for development of a recirculation cell. The Henry's Law constant for PCE is high, allowing it to be readily stripped from groundwater. The Density Driven Convection (DDC) technology controls vapor emissions at the well head, thereby eliminating concerns associated with the accumulation of fugitive soil vapors within the strip mall. SVE was selected to strip volatile organics from the unsaturated zone.

Date implemented:
October 1999

Final remediation design:
Eleven 4-inch-diameter DDC wells were installed. 5-ft-long lower screens were positioned just above bedrock; 5-ft upper screens were positioned between 20-25 ft bgs. The upper screens straddled the static water level. A bentonite seal was placed outside the well casing separating the two screened intervals. Approximately 10 scfm of air was injected into each well. The drop tubes were positioned approximately 15 ft below the static water level. Vapors produced within the wells were collected and directed through carbon prior to discharge to the atmosphere.

Results to date:
In 10 months, all dissolved PCE concentrations were reduced to levels below the 5 µg/L Rhode Island regulatory requirement. The system was turned off in August of 1999. Compliance monitoring was conducted to evaluate the potential for rebound. PCE concentrations remained below 5 µg/L for four quarters. The state of Rhode Island issued a No Further Action letter in the spring of 2000. The system was decommissioned in April of 2000.

Cost to Design and Implement:
$150,000 (estimated, for all technologies)

In Situ Recirculating Wells
 

Why the technology was selected:
The aquifer is interconnected and relatively permeable, allowing for development of a recirculation cell. The Henry's Law constant for PCE is high, allowing it to be readily stripped from groundwater. The Density Driven Convection (DDC) technology controls vapor emissions at the well head, thereby eliminating concerns associated with the accumulation of fugitive soil vapors within the strip mall. SVE was selected to strip volatile organics from the unsaturated zone.

Date implemented:
October 1999

Final remediation design:
Eleven 4-inch-diameter DDC wells were installed. 5-ft-long lower screens were positioned just above bedrock; 5-ft upper screens were positioned between 20-25 ft bgs. The upper screens straddled the static water level. A bentonite seal was placed outside the well casing separating the two screened intervals. Approximately 10 scfm of air was injected into each well. The drop tubes were positioned approximately 15 ft below the static water level. Vapors produced within the wells were collected and directed through carbon prior to discharge to the atmosphere.

Results to date:
In 10 months, all dissolved PCE concentrations were reduced to levels below the 5 µg/L Rhode Island regulatory requirement. The system was turned off in August of 1999. Compliance monitoring was conducted to evaluate the potential for rebound. PCE concentrations remained below 5 µg/L for four quarters. The state of Rhode Island issued a No Further Action letter in the spring of 2000. The system was decommissioned in April of 2000.

Cost to Design and Implement:
$150,000 (estimated, for all technologies)

In Situ Soil Vapor Extraction
 

Why the technology was selected:
The aquifer is interconnected and relatively permeable, allowing for development of a recirculation cell. The Henry's Law constant for PCE is high, allowing it to be readily stripped from groundwater. The Density Driven Convection (DDC) technology controls vapor emissions at the well head, thereby eliminating concerns associated with the accumulation of fugitive soil vapors within the strip mall. SVE was selected to strip volatile organics from the unsaturated zone.

Date implemented:
October 1999

Final remediation design:
Eleven 4-inch-diameter DDC wells were installed. 5-ft-long lower screens were positioned just above bedrock; 5-ft upper screens were positioned between 20-25 ft bgs. The upper screens straddled the static water level. A bentonite seal was placed outside the well casing separating the two screened intervals. Approximately 10 scfm of air was injected into each well. The drop tubes were positioned approximately 15 ft below the static water level. Vapors produced within the wells were collected and directed through carbon prior to discharge to the atmosphere.

Results to date:
In 10 months, all dissolved PCE concentrations were reduced to levels below the 5 µg/L Rhode Island regulatory requirement. The system was turned off in August of 1999. Compliance monitoring was conducted to evaluate the potential for rebound. PCE concentrations remained below 5 µg/L for four quarters. The state of Rhode Island issued a No Further Action letter in the spring of 2000. The system was decommissioned in April of 2000.

Cost to Design and Implement:
$150,000 (estimated, for all technologies)

Costs

Cost for Assessment:
  Not available
Cost for Operation and Maintenance:
  $20,000/year (estimated) for one year
Total Costs for Cleanup:
 

Lessons Learned

1. Glacial deposits at the site contained intermittent boulders; some wells had to be installed with a Barber rig and air hammer bit.

Contacts

Jeffery Crawford
Rhode Island Department of Environmental Mangement
235 Promenade Street
Providence, RI 02908-5767
401-222-2797, ext 7102
401-222-3812 (fax)
jcrawfor@dem.state.ri.us

Boyd Breeding
Wasatch Environmental
2410 West California Ave.
Salt Lake City, UT 84104
801-972-8400
breedingwei@aol.com