Drycleaner Site Profiles

Pinehurst Hotel Cleaners, Pinehurst, North Carolina

Description
Historical activity that resulted in contamination.

Drycleaning was performed on-site from the 1930's through the 1970's. The site is currently vacant.

Remediation Status: In groundwater monitoring


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


Contaminant Media Concentration (ppb) Nondetect
Benzene soil
chloroform soil
cis-1,2-Dichloroethene groundwater
cis-1,2-Dichloroethene soil
Tetrachloroethene (PCE) groundwater
Tetrachloroethene (PCE) soil
naphthalene groundwater
Trichloroethene (TCE) groundwater
Trichloroethene (TCE) soil
m-Xylene soil
o-Xylene soil
p-Xylene soil

Site Hydrology

Deepest Significant Groundwater Contamination:   40ft bgs
Plume Size:   Plume Length: 785ft
Plume Width: 395ft
Plume Thickness: 40ft
Average Depth to Groundwater:   13.5ft

Lithology and Subsurface Geology

 
  Interbedded mixture of sands, silty sands, and clayey sand

Conductivity: 0.0028ft/day
Gradient: 0.01ft/ft

Pathways and DNAPL Presence

Groundwater
Sediments
Soil
DNAPL Present

Vapor Intrusion Pathway

Has the potential for vapor intrusion (VI) been evaluated?
  Yes
How was the site evaluated?
  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 

Remediation Scenario

Cleanup Goals:
  Cleanup goals are achievement of plume stability and mitigation of surface water impacts.
Remedy Level:
  Full Scale Remedy

Technologies

In Situ Bioremediation
 

Why the technology was selected:
Phytoremediation was selected to mitigate surface water impacts based on a cost evaluation and to comply with area stakeholder concerns (i.e. "green" technology more acceptable to town and area property owners). Source area injection and soil removal performed based on prior success with this technology at similar sites.

Date implemented:
October 2008

Final remediation design:
Excavation to remediate source area soil, chemical injection to remediate source area groundwater, and phytoremediation to mitigate surface water impacts downgradient.

Other technologies used:
Phytoremediation and on-site treatment of excavated soils via mobile steam distillation unit.

Results to date:
Plume appears generally stable and surface water impacts have been successfully mitigated.

Next Steps:
Continue to maintain phytoremediation system to ensure continued mitigation of stream impacts. Monitor groundwater periodically to ensure plume stability.

Cost to Design and Implement:
$471,328 for all technologies

In Situ Zero Valent Iron
 

Why the technology was selected:
Phytoremediation was selected to mitigate surface water impacts based on a cost evaluation and to comply with area stakeholder concerns (i.e. "green" technology more acceptable to town and area property owners). Source area injection and soil removal performed based on prior success with this technology at similar sites.

Date implemented:
October 2008

Final remediation design:
Excavation to remediate source area soil, chemical injection to remediate source area groundwater, and phytoremediation to mitigate surface water impacts downgradient.

Other technologies used:
Phytoremediation and on-site treatment of excavated soils via mobile steam distillation unit.

Results to date:
Plume appears generally stable and surface water impacts have been successfully mitigated.

Next Steps:
Continue to maintain phytoremediation system to ensure continued mitigation of stream impacts. Monitor groundwater periodically to ensure plume stability.

Cost to Design and Implement:
$471,328 for all technologies

Ex Situ Soil Removal
 

Why the technology was selected:
Phytoremediation was selected to mitigate surface water impacts based on a cost evaluation and to comply with area stakeholder concerns (i.e. "green" technology more acceptable to town and area property owners). Source area injection and soil removal performed based on prior success with this technology at similar sites.

Date implemented:
October 2008

Final remediation design:
Excavation to remediate source area soil, chemical injection to remediate source area groundwater, and phytoremediation to mitigate surface water impacts downgradient.

Other technologies used:
Phytoremediation and on-site treatment of excavated soils via mobile steam distillation unit.

Results to date:
Plume appears generally stable and surface water impacts have been successfully mitigated.

Next Steps:
Continue to maintain phytoremediation system to ensure continued mitigation of stream impacts. Monitor groundwater periodically to ensure plume stability.

Cost to Design and Implement:
$471,328 for all technologies

Costs

Cost for Assessment:
  $253,139
Cost for Operation and Maintenance:
  $91,317
Total Costs for Cleanup:
  on-going

Lessons Learned

There were some concerns over whether reductive dechlorination could be acheived via chemical injection because of high dissolved oxygen levels in groundwater. A layer of mulch was spread on-site prior to injection and appeared to assist in achievement of reducing conditions. Also, costs for maintenance of phytoremediation system were more than expected.

Contacts

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

Genna Olson, ATC Associates Inc., 2725 East Millbrook Road, Suite 121, Raleigh, NC 27604, (919) 871-0999, genna.olson@atcassociates.com

Site Specific References

1/27/09 Soil Excavation Letter Report, 3/16/10 Interim Remedial Action Activities Report, 2/8/12 Interim Remedial Action Activities Report, 6/22/12 Injection Evaluation Report