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 1, 2011

Point of Contact:
Andy Park
USEPA
290 Broadway
New York NY 10007-1866 
Tel: 212-637-4184 
Email: park.andy@
epa.gov

GE Hudson Falls
Hudson Falls, NY


Hydrogeology:

The Site is located on the eastern bank of the Hudson River adjacent to the Bakers Falls dam. The stratigraphic units that have been identified beneath the Site are the overburden, the
Snake Hill Shale, the Glens Falls Limestone, and the Isle La Motte Limestone. Beneath the Site, the overburden, which consists of fill, sand, clay and till, ranges in thickness from two to 21 feet. The bedrock formations generally strike north-northeast, have an undulatory surface, and dip approximately three to five degrees to the southeast. The Snake Hill Shale, which is the uppermost bedrock formation, ranges in thickness from 150 to 250 feet beneath the Site. For the purpose of the Site investigations and evaluations, this formation has been subdivided into the upper Snake Hill Shale, middle Snake Hill Shale, and lower Snake Hill Shale. The Glens Falls Limestone and Isle La Motte Limestone, which are beneath the Snake Hill Shale, are approximately 100 and 60 feet thick, respectively.

There are three steeply dipping fracture sets in the Snake Hill Shale. The best-developed of these fracture sets trends approximately northeast-southwest. The two other fracture sets trend approximately northwest-southeast and approximately north-south, respectively. There are two laterally continuous nearly horizontal thrust fault planes that are generally parallel to bedding and are usually contained within the middle Snake Hill Shale. One is referred to as the upper fault plane, and the other is referred to as the lower fault plane.

Hydraulic testing data indicate that the hydraulic conductivity of the middle Snake Hill Shale is greater than the hydraulic conductivity of the upper and lower Snake Hill Shale. Wells open to only the upper and lower Snake Hill Shale units generally do not produce much water due to the lower hydraulic conductivity of these units. The greater hydraulic conductivity of the middle Snake Hill Shale is likely due to the presence of several approximately horizontal fractures that are associated with the upper and lower fault planes. Within the Shake Hill Shale, the vertical fracture sets and the bedding-parallel fault planes and fracture zones are the principal geologic controls on the occurrence and movement of groundwater and contaminants.

Targeted Environmental Media:
  • - Dense Non-aqueous Phase Liquids (DNAPLs)
  • - Fractured Bedrock

Contaminants:

The bedrock plume including DNAPLs is about 500 by 900 feet and extends over 200 feet deep.

Major Contaminants and Maximum Concentrations:
  • - Aroclor 1242 (2,100,000 µg/L)
  • - Aroclor 1254 (74,000 µg/L)
  • - Trichloroethene (130,000 µg/L)
  • - 1,2-Dichloroethene (120,000 µg/L)
  • - 1,1,1-Trichloroethane (16,000 µg/L)
  • - Vinyl chloride (38,000 µg/L)
  • - Bis(2-ethylhexyl) phthalate (1,100,000 µg/L)
  • - 1,4-Dichlorobenzene (11,000 µg/L)
  • - 1,2,4-Trichlorobenzene (69,000 µg/L)
  • - 1,2-Dichlorobenzene (5,000 µg/L)

Site Characterization Technologies:

  • - Pumping Tests

Remedial Technologies:

  • - Pump and Treat
  • - Multi Phase Extraction
Comments:
The first groundwater recovery wells began pumping in 1996. The contaminants listed above are a sampling of the chemicals found at the site. Also found at the site is phenyl xylyl ethane, which is a substitute dielectric fluid for PCBs.
Remediation Goals:

The cleanup goals for groundwater are the New York State Water Quality Criteria.


Status:

A 24-foot diameter vertical access shaft was constructed to a depth of about 200 feet Three 10-foot by 10-foot horizontal tunnels were excavated from the access shaft beneath and adjacent to the river bed. The total length of tunnel excavated was 1000 feet. A series of slanted boreholes were drilled up from the collection tunnel. These boreholes collect water and NAPL and transport them to the tunnel and a sump where they are pumped to the surface for treatment. The tunnel was finished at the end of 2008.

http://www.dec.ny.gov/chemical/8677.html

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For more information on Fractured Bedrock, please contact:

Ed Gilbert
Technology Assessment Branch

PH: (703) 603-8883 | Email: gilbert.edward@epa.gov