Project Description: The goal of the Alternative Cover Assessment Program (ACAP) is the development of field-scale performance data for landfill final cover systems. Both prescriptive (RCRA) and innovative alternative cover designs are currently being tested in the project. ACAP is part of the U.S. Environmental Protection Agency (EPA) - National Risk Management Research Laboratory's (NRMRL) Superfund Innovative Technology Evaluation (SITE) Program established to promote the development of new and innovative technologies used to address hazardous waste problems. ACAP is divided into two phases.
Phase 1 (completed August 1999) involved the assessment of potential sites and research facilities, existing designs, existing modeling methods, and recommendations for implementing Phase 2. The assessment took the form of literature reviews, contact with researchers and site owners, and input from regulators and is available as an EPA report.
Phase 2 involves the establishment of a network of twelve demonstration field sites nationwide. Selected sites include municipal solid waste landfills, a Department of Defense hazardous waste landfill, a commercial hazardous waste landfill, and a Department of Energy uranium mine tailings disposal site. Field data will be collected from these field demonstrations for five years.
A primary function of a landfill final cover system is to minimize deep percolation to prevent surface and groundwater contamination. Landfill and waste site covers are constructed to meet the requirements of current regulatory guidance, and typically rely on a combination of layers of specified thickness to limit percolation through the cover.
The large costs associated with the construction of the landfill and waste site covers and the desire for constant innovation and performance improvement has resulted in a growing interest for alternative designs. It is ACAP's goal to evaluate the various proposed alternative cover systems. ACAP is currently focusing on evapotranspiration (ET) type covers. ET covers utilize plants to cycle water from the soil profile to the atmosphere during the growing season thus minimizing year-round drainage from the cover system.
Demonstration Status: Test sections have been installed at landfills in Sacramento County, California; Lake County, Montana; Lewis & Clark County, Montana; Monticello, Utah; Cedar Rapids, Iowa; Omaha, Nebraska; Boardman, Oreg on; Altamont, California; Monterey, California. and the Marine Corps Logistics Base in Albany, Georgia. In addition, retrofit monitoring (to study existing alternative covers constructed prior to ACAP) has been established in Cincinnati and Logan, Ohio.
The basic components of the alternative covers for these sites are vegetation and soil. Different communities of trees, shrubs, and grasses are incorporated depending on local soil and climatological conditions. The cover soil is generally local soil, with depth differing in accordance with soil water holding capacity, precipitation patterns, and vegetation selected. Several of the sites include a prescriptive RCRA cover test section. Such side-by-side comparisons will allow direct evaluation of the performance of an alternative to meet or exceed that of the conventional, prescriptive cover.
Each site will contain at least one test section (10 meters x 20 meters) that consists of a large-scale, pan-type lysimeter (see Figure 1) to monitor percolation through tested covers over a period of five years. The lysimeter is constructed of low-density polyethylene. The bottom of the lysimeter is sloped and contains a drainage composite to direct flow of water to a sump for collection and measurement.
During the five years, EPA will monitor and record the climatological conditions (rainfall, snowfall, air temperature, solar radiation, and humidity), and soil parameters (moisture content, moisture potential, and temperature) of each test section. Data will be recorded on a data logger connected to a telemetry unit. The telemetry unit allows remote communication with the data logger and enables data to be downloaded, stored, and analyzed for performance and system status.
Annually during the five years of this project, EPA will release performance reports for each site. EPA predicts that the data collected through ACAP will lead to the development of new computer models for designing and evaluating future landfill covers, new designs, and new methods to regulate such systems. The ACAP Phase II team currently consists of Michael Bolen and Art Roesler of Science Applications International Corporation, Dr. Craig Benson and Dr. Tarek Abichou of the University of Wisconsin, Bill Albright and Brad Lyles of the Desert Research Institute, Dr. Glendon Gee and Jason Ritter of Battelle - Pacific Northwest Division, and active participation and support from each of the site owners, engineers, and consultants.
For Further Project Information:
EPA Project Manager
Steve Rock
U.S. EPA
National Risk Management Research Laboratory (NRMRL)
26 W. Martin Luther King Jr. Dr.
Cincinnati, OH 45268
(513) 569-7149
rock.steven@epa.gov
For Questions or Comments about the web pages:
DRI Project Manager
Bill Albright
Desert Research Institute
Reno, Nevada 89512
(775) 673-7314
billa@dri.edu
