Permeable Reactive Barriers (PRBs) Interim Summary Report: PRBs Using a Funnel and Gate Configuration

Site Name:

Multiple (14) Sites

Location:

- Aircraft Maintenance Facility, Southern Oregon
- Federal Highway Administration Facility, Lakewood, Colorado
- Former Manufacturing Site, Seattle, Washington
- Industrial Site, Coffeyville, Kansas
- Intersil Semiconductor Site, Sunnyvale, California
- Vapokon Petrochemical Work, Sonderso, Denmark
- Alameda Point, Alameda, California
- Area 5, Dover Air Force Base (AFB), Dover, Delaware
- Lowry AFB, Denver, Colorado
- Moffett Federal Airfield, Mountain View, California
- Former Mill Site, Monticello, Utah
- East Garrington, Alberta, Canada
- Fry Canyon Site, Fry Canyon, Utah
- Y-12 Site, Oak Ridge National Laboratory, Oak Ridge, Tennessee

Period of
Operation:

Installation dates ranging from 1995 (Intersil and East Garrington) - 2000 (Alameda Point)

Cleanup
Type:

Full scale and field demonstrations The funnel and gate PRB configuration involves the use of engineered subsurface barriers to capture and route groundwater flow through one or more gates, where treatment occurs. In most cases, funnels have been comprised of sheet piling or slurry cutoff walls. However, engineered preferential groundwater flow pathways employing channels (sometimes referred to as "trench and gate" systems) also have been used to route groundwater flow to a reactive gate.

Technology:
Permeable Reactive Barriers using a funnel and gate configuration:

- Aircraft Maintenance Facility- continuous trenching/ supported excavation, iron and sand
- Federal Highway Administration Facility- supported excavation, iron
- Former Manufacturing Site- supported excavation, iron and sand
- Industrial Site- construction method not provided, iron
- Intersil Semiconductor Site- construction method not provided, iron
- Vapokon Petrochemical Work- supported excavation, iron
- Alameda Point- supported excavation, iron and oxygen
- Area 5, Dover Air Force Base (AFB)- supported excavation, iron
- Lowry AFB- supported excavation, iron
- Moffett Federal Airfield- continuous trenching, iron
- Former Mill Site- supported excavation, iron
- East Garrington- supported excavation, oxygen
- Fry Canyon Site- installation method not provided, iron, amorphous ferric oxide, phosphate
- Y-12 Site, Oak Ridge National Laboratory- supported excavation, iron

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

Contacts:
Varied by site

Contaminants:
Chlorinated Solvents, Other Organics, Metals, Inorganics, Radionuclides
- TCE, PCE, DCE, DCA, vinyl chloride, dichloromethane
- Benzene, toluene, ethylbenzene, xylene, Freon
- Uranium, arsenic, manganese, selenium, vanadium
- Maximum influent concentrations for individual contaminants in each category were 50,000 µg/L (PCE); 60 µg/L (Freon); and 20,700 µg/L (uranium)

Waste Source:
Varied by site

Type/Quantity of Media Treated:
Groundwater

Purpose/Significance of Application:
Use of PRBs with a funnel and gate configuration to treat contaminated groundwater.

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

Results:
Performance data was provided for the seven full-scale PRBs included in this report (Aircraft Maintenance Facility, Federal Highway Administration Facility, Former Manufacturing Site, Industrial Site, Intersil Semiconductor Site, Vapokon Petrochemical Work, and Former Mill Site). Five of the seven PRBs with performance data were meeting cleanup goals for chlorinated VOCs and reduced concentrations of individual contaminants from a high of 50,000 µg/L to concentrations below maximum contaminant levels (MCL) or other site-specific cleanup levels.

Cost Factors:
Installation cost information was available for 13 of the 14 projects included in the report. No information concerning PRB operation and maintenance costs was provided for any site. Design costs ranging from $30,000 to $240,000 per site were provided for four of the sites (Former Manufacturing Facility, Vapokon Petrochemical Work, Moffett Federal Airfield, and Fry Canyon Site). The installation cost per site (excluding design costs when provided) ranged from $67,200 for East Garrington to $1 million for the Federal Highway Administration Facility, Intersil Semiconductor, and Y-12 sites.

Description:
This report provides an interim summary of information about fourteen projects (seven full-scale and seven pilot-scale) involving the application of PRB technologies where a funnel and gate configuration was used to treat groundwater contaminated with chlorinated solvents, other organic contaminants, and/or inorganic contaminants. In most cases, funnels have been comprised of sheet piling or slurry cutoff walls. However, engineered preferential groundwater flow pathways employing channels (sometimes referred to as "trench and gate" systems) also have been used to route groundwater flow to a reactive gate under low-permeability aquifer conditions.

Lessons learned at the PRB sites summarized in this report include those related to specific successes and issues associated with installing funnel and gate configurations under various environmental conditions and the suitability of several reactive media for addressing contamination at specific sites.