U.S. EPA Contaminated Site Cleanup Information (CLU-IN)


U.S. Environmental Protection Agency
U.S. EPA Technology Innovation and Field Services Division

Fractured Bedrock Project Profiles

Last Updated: January 2, 2011

Point of Contact:
Darryl Luce
5 Post Office Square, Suite 100
Mail Code OSRR07-1
Boston MA 02109 
Tel: 918-1336 
Email: luce.darryl@
epa.gov

Sylvester
Nashua, NH


Hydrogeology:

The Site geology consists of a 30 to 90-foot thick layer of stratified sands and gravels overlying a thin layer of glacial till which rests on bedrock. The sands are approximately 30 feet thick in the southern portion of the Site and deepen to the northwest. The water table lies approximately 10 to 15 feet below the ground surface at the highest point at the Site.

Throughout the area, groundwater flows northwest to the Nashua River. Groundwater at the Site may be divided into two units: an upper, surficial aquifer that consists of stratified
glacial drift ("overburden") that is very permeable and a lower, bedrock aquifer separated from the overburden aquifer by a discontinuous, basal, glacial till with discontinuous flow.

Targeted Environmental Media:
  • - Fractured Bedrock

Contaminants:

Major Contaminants and Maximum Concentrations:
  • - 1,2-Dibromoethane (73,000 µg/L)
  • - Acetone (310,000 µg/L)
  • - Methylene chloride (122,500 µg/L)
  • - 2-Butanone (MEK) (80,000 µg/L)
  • - Tetrahydrofuran (1,500,000 µg/L)
  • - Chloroform (31,000 µg/L)
  • - Isopropyl alcohol (26,000 µg/L)
  • - Toluene (29,000 µg/L)
  • - 4-Methyl-2-pentanone (MIBK) (21,000 µg/L)
  • - Diethyl ether (20,000 µg/L)

Site Characterization Technologies:

No technologies selected.


Remedial Technologies:

  • - Pump and Treat
Comments:
A slurry wall was placed around the source area and keyed into the bedrock. It was anticipated that this would not stop contaminated bedrock groundwater from escaping. Extraction wells within the the slurry wall pumped on the overburden aquifer with treated water being reinjected into the bedrock outside the slurry wall to help create a gradient barrier. The groundwater plume outside the source area was not addressed. The pump and treat system operated until 1996 when it was turned off. Over 430,000 pounds of chemicals were recovered.
Remediation Goals:

VINYL CHLORIDE 95 UG/L
BENZENE 340 UG/L
CHLOROFORM 1505 UG/L
1,1,2 TRICHLOROETHANE 1.7 UG/L
TETRACHLOROETHYLENE 57 UG/L
TRICHLOROETHYLENE 1500 UG/L
METHYL ETHYL KETONE 8000 UG/L
CHLOROBENZENE 110 UG/L
METHYLENE CHLORIDE 12250 UG/L
TOLUENE 2900 UG/L
1,1 DICHLOROETHANE 1.5 UG/L
TRANS-1,2-DICHLOROETHANE 1800 UG/L
1,1,1 TRICHLOROETHANE 200 UG/L
METHYL METHACRYLATE 350 UG/L
SELENIUM 2.6 UG/L
PHENOLS 400 UG/L.


Status:

The surrent status of the site is it is in a long term monitoring mode.

http://cfpub.epa.gov/supercpad/cursites/csitinfo.cfm?id=0101115

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