Alternative Cover Assessment Research Program

Kiefer Landfill, Sacramento CADRI’s Alternative Cover Assessment Program (ACAP) is an innovative partnership of industry, the USEPA, other federal agencies, state regulatory agencies, and scientists and engineers from four major research institutions. The program grew out of an opportunity to respond to the needs of both the landfill industry and regulatory agencies to provide environmentally responsible and cost effective methods to close landfills.

The basis for ACAP was a nation-wide network of field research sites. Large drainage lysimeters provided the opportunity for detailed study of the complex relation between soil, plants, water, and climate. After nearly a decade of field work and analysis, ACAP has yielded a new technology and engineering methods based on sound science.

The economic benefits of ACAP are striking. Realized and projected savings already exceed $200M. State and federal regulations already reflect the knowledge gained from a truly collaborative effort by regulatory agencies and a regulated industry.

Benefits to the Environment and the Public

Craig Benson prepares a dye tracer experiment for ACAP.Unlike the conventional methods for landfill closure that rely on material properties (layers of compacted clay and plastic membranes) to resist natural processes, alternative designs rely on a site-specific design process to match soils and plants to the climate. The result can be a final closure that works with, not against, nature to provide improved protection of ground water, control of greenhouse gas emissions and better end land use.

Additionally, the US ACAP research team is advising several Australian universities on a related program (see and