Cost-Effective Landfill Monitoring, 1998 Environmental Conference Proceedings

Eric Tuppan

EMCON

Chris Haynes

Weyerhaeuser Company

The Weyerhaeuser Regional Landfill in southwest Washington, a composite-lined facility that receives wood waste from Oregon and Washington after the waste stream is reduced through recycling and other measures, has extensive environmental mitigation and permit requirements for groundwater and surface water monitoring. By using a tiered approach that takes advantage of the landfill’s engineered features, the facility saves 40 percent a year on monitoring costs. A full suite of parameters is regularly screened for in the first tier (leachate collection and removal system [LCRS]), where contaminants are most likely to be found (i.e., in leachate). Only a limited set of indicator parameters is regularly monitored for in the other tiers: the permeable hydraulic gradient control system (HGCS) beneath the entire landfill liner, and groundwater monitoring wells along the landfill’s compliance boundary (downgradient edge). If a contaminant is detected above a threshold value in the first tier (LCRS), then monitoring in other tiers is increased. Monitoring costs are lowered because (1) fewer parameters require sampling, (2) fewer monitoring wells are required along the compliance boundary (the HGCS monitors a broader area under the landfill than possible with isolated wells), and (3) fewer data are generated, reducing management, validation, and reporting requirements.