Drycleaner Site Profiles

Mitchell's Formal Wear, Charlotte, North Carolina

Description
Historical activity that resulted in contamination.

Mitchell' Formal Wear was previously located in a mixed use shopping center, adjacent to residential properties. The facility conducted drycleaning operations using PCE from 1979 to 2001 and petroleum-based solvent from 2001 to 2002, at which time the business stopped operations.

Remediation Status: In groundwater monitoring


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


Contaminant Media Concentration (ppb) Nondetect
Benzene groundwater
Benzene soil
chloroform groundwater
chloroform soil
cis-1,2-Dichloroethene groundwater
1,2-Dichloroethane groundwater
1,1-Dichloroethene groundwater
ethylbenzene groundwater
methylene chloride groundwater
n-propylbenzene groundwater
Tetrachloroethene (PCE) groundwater
Tetrachloroethene (PCE) soil
1,2,4-trimethylbenzene groundwater
1,2,4-trimethylbenzene soil
1,3,5-trimethylbenzene groundwater
naphthalene groundwater
naphthalene soil
Trichloroethene (TCE) groundwater
Trichloroethene (TCE) soil
Vinyl Chloride groundwater
Vinyl Chloride soil
1,2-Dichloroethene groundwater

Site Hydrology

Deepest Significant Groundwater Contamination:   90ft bgs
Plume Size:   Plume Length: 1,550ft
Plume Width: 700ft
Plume Thickness: 90ft
Average Depth to Groundwater:   17.8ft

Lithology and Subsurface Geology

 
  interbedded clayey silt, sandy silt and silty sand which generally coursens with depth
Depth: 0-50ft bgs
50ft thick
Conductivity: 0.11ft/day
Gradient: 0.02ft/ft
 
  granite bedrock
Depth: 50ft bgs

Pathways and DNAPL Presence

Groundwater
Sediments
Soil
checkPresumptive Evidence of DNAPL

Vapor Intrusion Pathway

Has the potential for vapor intrusion (VI) been evaluated?
  Yes
How was the site evaluated?
  Soil vapor and/or Sub-slab vapor sampling,Indoor air sampling,Groundwater sampling,Compared sample concentration to screening criteria,Used an exposure screening model
Results of VI evaluation:
  A completed VI pathway has been indentified,A potential VI pathway has been indentified
Has a vapor mitigation system been installed?
  Yes 
Type of Vapor Mitigation System(s):
  HVAC controls/modifications
Additional VI Information:
  Operation of a large fan in the former drycleaning area successfully reduced indoor air concentrations to below acceptable levels.

Remediation Scenario

Cleanup Goals:
  Demonstration of plume stability.
Remedy Level:
  Full Scale Remedy

Technologies

In Situ Air Sparging
 

Why the technology was selected:
BOS-100 was used for groundwater remediation based on favorable pilot testing data. Chemical oxidation, air sparge, and aggressive fluid vapor recovery (AFVR) were previously performed with less favorable results.

Date implemented:
AFVR events were performed on March 4 and July 6, 1999. An air sparge pilot test was performed in 2002. Potassium permanganate injections were performed in 2003. Source area soil excavations were performed in 2003, and 2007. The BOS-100 pilot test was

Final remediation design:
Groundwater remediation was ultimately completed via BOS-100 injection. Accessible impacted soil has been excavated, but additional impacted soil excavation will likely be performed after planned demolition of the building is completed.

Results to date:
The BOS-100 injection was successful in significantly reducing source area contaminant concentrations. Pre and post-injection monitoring data for the monitoring wells in the injection area indicated significant reductions in PCE concentrations, and no significant increases in PCE-breakdown products.

Next Steps:
Redevelopment of the site is currently planned which will involve demolition of the building. Following demolition additional impacted soil will be excavated. Site closure is expected following the soil excavation.

Cost to Design and Implement:
$118,727

In Situ Chemical Oxidation
 

Why the technology was selected:
BOS-100 was used for groundwater remediation based on favorable pilot testing data. Chemical oxidation, air sparge, and aggressive fluid vapor recovery (AFVR) were previously performed with less favorable results.

Date implemented:
AFVR events were performed on March 4 and July 6, 1999. An air sparge pilot test was performed in 2002. Potassium permanganate injections were performed in 2003. Source area soil excavations were performed in 2003, and 2007. The BOS-100 pilot test was

Final remediation design:
Groundwater remediation was ultimately completed via BOS-100 injection. Accessible impacted soil has been excavated, but additional impacted soil excavation will likely be performed after planned demolition of the building is completed.

Results to date:
The BOS-100 injection was successful in significantly reducing source area contaminant concentrations. Pre and post-injection monitoring data for the monitoring wells in the injection area indicated significant reductions in PCE concentrations, and no significant increases in PCE-breakdown products.

Next Steps:
Redevelopment of the site is currently planned which will involve demolition of the building. Following demolition additional impacted soil will be excavated. Site closure is expected following the soil excavation.

Cost to Design and Implement:
$118,727

In Situ Multi Phase Extraction
 

Why the technology was selected:
BOS-100 was used for groundwater remediation based on favorable pilot testing data. Chemical oxidation, air sparge, and aggressive fluid vapor recovery (AFVR) were previously performed with less favorable results.

Date implemented:
AFVR events were performed on March 4 and July 6, 1999. An air sparge pilot test was performed in 2002. Potassium permanganate injections were performed in 2003. Source area soil excavations were performed in 2003, and 2007. The BOS-100 pilot test was

Final remediation design:
Groundwater remediation was ultimately completed via BOS-100 injection. Accessible impacted soil has been excavated, but additional impacted soil excavation will likely be performed after planned demolition of the building is completed.

Results to date:
The BOS-100 injection was successful in significantly reducing source area contaminant concentrations. Pre and post-injection monitoring data for the monitoring wells in the injection area indicated significant reductions in PCE concentrations, and no significant increases in PCE-breakdown products.

Next Steps:
Redevelopment of the site is currently planned which will involve demolition of the building. Following demolition additional impacted soil will be excavated. Site closure is expected following the soil excavation.

Cost to Design and Implement:
$118,727

Ex Situ Soil Removal
 

Date implemented:
AFVR events were performed on March 4 and July 6, 1999. An air sparge pilot test was performed in 2002. Potassium permanganate injections were performed in 2003. Source area soil excavations were performed in 2003, and 2007. The BOS-100 pilot test was

Final remediation design:
Groundwater remediation was ultimately completed via BOS-100 injection. Accessible impacted soil has been excavated, but additional impacted soil excavation will likely be performed after planned demolition of the building is completed.

Results to date:
The BOS-100 injection was successful in significantly reducing source area contaminant concentrations. Pre and post-injection monitoring data for the monitoring wells in the injection area indicated significant reductions in PCE concentrations, and no significant increases in PCE-breakdown products.

Next Steps:
Redevelopment of the site is currently planned which will involve demolition of the building. Following demolition additional impacted soil will be excavated. Site closure is expected following the soil excavation.

Cost to Design and Implement:
$118,727

Costs

Cost for Assessment:
  $403,552
Cost for Operation and Maintenance:
  $0
Total Costs for Cleanup:
  On-going

Lessons Learned

Direct-push sampling was performed prior to injection to locate source areas and specifically target injection areas. The targeted injection is considered the key to remediation success at this site. It was also found that in tight soils multiple injections reduces the potential for day-lighting issues.

Contacts

Delonda Alexander, NC DSCA Program, 1646 Mail Service Center, Raleigh, North Carolina 27699-1646, (919) 707-8365, delonda.alexander@ncdenr.gov

Site Specific References

7/14/2011 Injection Evaluation Report