Drycleaner Site Profiles

Pro Cleaners #920001, Raleigh, North Carolina

Description
Historical activity that resulted in contamination.

A former "Perc" facility that operated until 1998 located in a tenant space of a single-story strip shopping center built slab on grade with multiple adjacent commercial tenants. No previous incidents were reported at the site prior to discovery date. Site was discovered in June 1995 by property owner during Phase II assessment for a property transaction. Probable source of contamination is unknown but is most likely related to historical daily operations and use in solvent storage, handling, and waste management practices prior to establishment of state release prevention regulations implemented in 1997. The targeted source area is the subsurface soils and groundwater immediately underneath the shopping center tenant spaces below and directly behind the dry cleaning facility and along the sanitary sewer system.

Remediation Status: In active remediation


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


Contaminant Media Concentration (ppb) Nondetect
Benzene groundwater
chloroform groundwater
cis-1,2-Dichloroethene groundwater
1,2-Dichloroethane groundwater
methylene chloride groundwater
Tetrachloroethene (PCE) groundwater
Tetrachloroethene (PCE) soil
Trichloroethene (TCE) groundwater
Vinyl Chloride groundwater

Site Hydrology

Deepest Significant Groundwater Contamination:   148ft bgs
Plume Size:   Plume Length: 780ft
Plume Width: 280ft
Plume Thickness: 148ft
Average Depth to Groundwater:   32.51ft

Lithology and Subsurface Geology

 
  Silty sand
Depth: 0-10ft bgs
10ft thick
Conductivity: 1.89ft/day
Gradient: 0.02ft/ft
 
  partially weathered rock at a range
Depth: 10-92ft bgs
82ft thick
 
  Crabtree Creek gneiss
Depth: 92ft 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:
  The VI pathway was ruled out (or does not exist)
Has a vapor mitigation system been installed?
  No 
Additional VI Information:
  Previous interim actions were conducted beneath the tenant space to remove sub-slab soils when the tenant space was unoccuiped to mitigate the potential vapor intrusion pathway which was confirmed by post corrective action indoor air sampling.

Remediation Scenario

Cleanup Goals:
  To reduce contaminant concentrations so that the site risks do not exceed a cumulative cancer risk of 1E10-5 and a hazard index below 1.0 by reduction of groundwater plume size and concentrations to protect downgradient private water supply well users.
Remedy Level:
  Interim Action

Technologies

In Situ Bioremediation
 

Why the technology was selected:
The technology was selected primarily based on low cost compared to other options.

Date implemented:
In January 2009, approximately 5,200 gallons of ABC® and 500 pounds of ZVI were emplaced using two injection wells as a pilot test.

Final remediation design:
Full-scale implementation of the technology was not performed due to a lack of success during the pilot testing phase. Alternate remedial technologies are currently being evaluated.

Other technologies used:
Reductive dechlorination by injecting a mixture of Anaerobic Biochem (ABC®) plus Zero Valent Iron (ZVI), collectively described as ABC+®.

Results to date:
Data collected from pre and post-injection monitoring activities suggests that the injection activities were generally ineffective in reducing contaminant concentrations within the injection area. The primary challenge is the site geology and achieving adequate contact between the impacted groundwater and the injection mixture.

Next Steps:
Alternate remedial technologies are being evaluated for the site.

Cost to Design and Implement:
$186,528.40

In Situ Zero Valent Iron
 

Why the technology was selected:
The technology was selected primarily based on low cost compared to other options.

Date implemented:
In January 2009, approximately 5,200 gallons of ABC® and 500 pounds of ZVI were emplaced using two injection wells as a pilot test.

Final remediation design:
Full-scale implementation of the technology was not performed due to a lack of success during the pilot testing phase. Alternate remedial technologies are currently being evaluated.

Other technologies used:
Reductive dechlorination by injecting a mixture of Anaerobic Biochem (ABC®) plus Zero Valent Iron (ZVI), collectively described as ABC+®.

Results to date:
Data collected from pre and post-injection monitoring activities suggests that the injection activities were generally ineffective in reducing contaminant concentrations within the injection area. The primary challenge is the site geology and achieving adequate contact between the impacted groundwater and the injection mixture.

Next Steps:
Alternate remedial technologies are being evaluated for the site.

Cost to Design and Implement:
$186,528.40

Costs

Cost for Assessment:
  $219,914.82 - Includes approved reimbursed assessment costs submitted by owner prior to entry into the Program.
Cost for Operation and Maintenance:
  Not applicable.
Total Costs for Cleanup:
  Not applicable.

Lessons Learned

Injection was found to pose a significant challenge at this site due to the complex site hydrogeology and groundwater chemistry. Furthermore, the injection technology used was selected based on low price and perhaps was not as effective as other available technologies. A lab bench-scale test may have assited with identifying the limitations of using the selected technology and possibly identification of other better technologies available.

Contacts

Al Chapman, L.G. Project Manager
NCDENR - Division of Waste Managment DSCA Program
1646 Mail Service Center
Raleigh, NC 27699-1646
Phone: (919) 707-8368
Fax: (919) 707-8368
Email: Al.Chapman@ncdenr.gov
Website: www.ncdsca.org

Site Specific References

The site reports are available on the NCDENR document portal system located at https://edm.nc.gov/DENR-Portal/. To access the site reports, enter the DSCA site ID# 920001 in the ID Value field under Property criteria fields window, then click the Search button above the Content window. The list of reports for the site will appear in the Content window below the criteria search fields window. Right-clicking on the Adobe Acrobat symbol next to a report in the list will allow downloading, preview, and other options for that report.