Landfill Cap at Sandia National Laboratories, Albuquerque, New Mexico

Site Name:

Sandia National Laboratories

Location:

Albuquerque, NM

Period of
Operation:

July 1995 to July 2000

Cleanup
Type:

Field Demonstration

Technology:
Cap
- Four alternative landfill cover designs were demonstrated: (1) a geosynthetic clay liner (GCL) cover; (2) a capillary barrier cover; (3) an anisotropic barrier cover; and (4) an evapotranspiration (ET) soil cover
- Design characteristics included
- GCL cover: 90 cm thickness, 4 layers
- capillary barrier cover: 140 cm thickness, 4 layers
- anisotropic barrier cover: 105 cm thickness, 4 layers
- ET soil cover: 90 cm thickness, 2 layers
- These alternative covers were compared with conventional RCRA Subtitle C and D covers
- Each demonstration plot was 13 m wide by 100 m long, with the long dimension crowned in the middle; all layers had a 5% grade; the western slope was maintained at ambient conditions, and a sprinkler was installed on the eastern slope

Cleanup Authority:
Not provided

Technical Contacts:
Stephen F. Dwyer
Sandia National Laboratories
Phone: (505) 844-0595
E-mail: sfdwyer@sandia.gov
Management Contacts:
Skip Chamberlain
DOE SCFA
Phone: (301)903-7248

Scott McMullin
DOE SCFA
Phone: (803) 725-9596

John B. Jones
DOE CMST
Phone: (702) 295-0532
E-mail: jonesjb@nv.doe.gov

Contaminants:
None

Waste Source:
None - clean site

Type/Quantity of Media Treated:
Soil

Purpose/Significance of Application:
Field demonstration of alternative landfill covers

Regulatory Requirements/Cleanup Goals:
The following soil properties were used to evaluate performance: soil moisture, soil temperature, runoff and erosion, percolation and inter-flow, meteorology, and vegetation

Results:
- Preliminary water flux rate data showed that all cover designs, except the RCRA Subtitle D cover, were impermeable; the anisotropic and ET covers had efficiencies similar to the RCRA Subtitle C cover
- Additional findings included:
- GCL: did not perform as well as expected
- capillary barrier cover: the percolation rate for the first year was higher than expected, and slowed significantly in later years
- anisotropic barrier cover: performed well
- ET soil cover: performed well

Cost Factors:
- Actual unit construction costs were provided for the six covers; these included mobilization/demobilization, sub-grade preparation, materials, and labor
- Unit costs were: GCL cover - $89.99/m2; capillary barrier cover - $92.64/ m2; anisotropic barrier cover - $75.26/ m2; ET cover - $73.89/ m2; RCRA Subtitle C cover - $157.54/m2; RCRA Subtitle D - $51.40/m2

Description:
A field demonstration of four alternative landfill covers is being conducted at the Sandia National Laboratories in Albuquerque, New Mexico. The four covers - GCL, capillary barrier, anisotropic barrier, and ET - were compared in a side-by-side demonstration with RCRA Subtitles C and D covers. Each of the six demonstration plots was 13 m wide by 100 m long, and crowned in the middle. Results showed that all cover designs, except the RCRA Subtitle D cover, were impermeable, and that the anisotropic and ET covers had efficiencies similar to the RCRA Subtitle C cover. Based on the results from this study, an ET cover was selected to be deployed at the Mixed Waste Landfill at Sandia. The ET cover was projected to save $7.6 million over a 30 year period when compared with use of a RCRA Subtitle C cover.