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 6, 2011

Point of Contact:
Mark Ripperda
Mail Code SFD83
75 Hawthorne Street
San Francisco CA 94105 
Tel: 415-972-3028 
Email: Ripperda.Mark@
epa.gov

Schofield Barracks
Schofield, HI


Hydrogeology:

The relatively flat Schofield Plateau was formed as basaltic lava flowed from the adjacent Koolau and Waianae volcanoes to the east and west, respectively. The upper 100 to 200 feet of the basaltic bedrock within the Schofield Plateau is weathered saprolite. The saprolite consists of soil (primarily fine-grained materials including silt and clay) formed by in situ decomposition of the basaltic bedrock. The saprolite is underlain by relatively unweathered basaltic bedrock consisting of interbedded pahoehoe and a'a lava flows. The lava flows are
highly fractured with cinder and clinker zone.

Three types of groundwater systems have been identified in central Oahu: (1) the Schofield High-level Water Body, (2) basal groundwater, and (3) dike-impounded groundwater. The Schofield High-level Water Body is located beneath the Schofield Plateau, and subsequently, the site. This water body is bound to the east and west by dike-impounded groundwater and to the north and south by basal groundwater. Lower permeability rocks (possibly
volcanic dikes and/or buried ridges) structurally separate these groundwater systems from one another. The Schofield high-level aquifer has a high transmis- sivity and hydraulic conductivity.
The depth to groundwater at the site is approximately 600 feet below ground surface (bgs) (approximately 270 feet above mean sea level [msl]).

Targeted Environmental Media:
  • - Fractured Bedrock

Contaminants:

Vertical contamination is greater than 800 feet bgs.

Major Contaminants and Maximum Concentrations:
  • - Trichloroethene (63 µg/L)
  • - Carbon tetrachloride (Not given)

Site Characterization Technologies:

No technologies selected.


Remedial Technologies:

  • - Pump and Treat
Comments:
The remedy consists of treating the water from the three base production wells by air stripping before adding the water to the distribution system. Treatment began in 1986. Note the 63 ug/L for TCE above is from a sampling in the 2000s.
Remediation Goals:

MCLs for TCE and carbon tetrachloride (CCl4).


Status:

The treatment at the production well heads continues. Between 2002 and 2007 TCE and CCl4 concentration remained stable.

http://cfpub.epa.gov/supercpad/cursites/csitinfo.cfm?id=0902923

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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