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Permeable Reactive Barriers (PRBs) Interim Summary Report: PRBs Using Continuous Walls to Treat Metals

Site Name:

Multiple (5) Sites


- Haardkrom Site, Kolding, Denmark
- Chalk River Laboratories, Ontario, Canada
- Nickel Rim Mine Site, Sudbury, Ontario, Canada
- Tonolli Superfund Site, Nesquehoning, Pennsylvania
- U.S. Coast Guard Support Center,Elizabeth City, North Carolina

Period of

Installation dates ranging from 1995 (Nickel Rim Site) - 1999 (Haardkrom Site); Pilot and varies by site


Full scale

Permeable Reactive Barriers using a continuous wall to treat groundwater contaminated with metals:

- Haardkrom - Continuous trench, using iron
- Chalk River Laboratories - Supported excavation, using clinoptilolite (zeolite)
- Nickel Rim Mine - Unsupported excavation, using organic carbon
- Tonolli Superfund - Continuous trenching, using limestone
- U.S. Coast Guard Support Center - Continuous trenching, using iron

Cleanup Authority:
CERCLA, RCRA, and other regulatory programs
(varied by site)

Varied by site

Chlorinated Solvents, Metals, Inorganics, and Radionuclides
- Maximum influent concentrations of 4,320 µg/L for TCE
- Metals and inorganics - hexavalent chromium, nickel, iron, sulfite, lead, cadmium, arsenic, zinc, copper
- Strontium-90

Waste Source:
Varied by site

Type/Quantity of Media Treated:

Purpose/Significance of Application:
Use of PRBs with a continuous wall configuration to treat groundwater contaminated primarily with metals

Regulatory Requirements/Cleanup Goals:
Regulatory requirements and cleanup goals vary by site

Of the five PRBs included in this case study, three (Nickel Rim Mine site, Chalk River Laboratories, and U.S. Coast Guard Support Center) have met or were meeting their performance goals, based on information available at the time of report preparation. At these sites, individual contaminant concentrations were reduced to below site-specific cleanup goals. The Haardkrom site had not met its goals, and the Tonolli Superfund site did not provide performance data.

Cost Factors:
Installation cost (excluding design when provided) information was available for four of the five projects in this case study: Haardkrom site $250,000; Chalk River Laboratories $300,000; Nickel Rim Mine Site $30,000; U.S. Coast Gaurd Support Center $500,000

This report provides an interim summary of information about five full-scale projects involving the application of continuous wall PRB technologies for the treatment of groundwater contaminated with metals and other inorganic materials. Several different reactive media were used in these applications and results were provided where available.

Continuous walls have been used to intercept and treat groundwater contaminated with metals without significantly affecting groundwater flow. Lessons learned at the PRB sites summarized in this report include those related to specific successes and issues associated with installing continuous walls under various environmental conditions and the suitability of several less common reactive media (organic carbon, limestone, zeolite) for addressing contamination at specific sites.