Investigation of Potential Groundwater Impacts at Yard Waste Compost Sites

Abstract: Yard waste composting facilities have steadily expanded in the state of Wisconsin. There is some concern regarding these types of facilities because, under certain circumstances, water percolating through yard wastes can generate a leachate that could potentially impact surface water and/or ground water quality. To quantify these potential impacts, the WDNR began a detailed study of two selected yard waste compost sites in Wisconsin.

Groundwater monitoring wells were installed at two operating compost facilities and sampled over the course of the study. Leachate samples were collected at the two study sites and at two other yard waste compost facilities.

The ground water sampling results indicate that downgradient wells at both sites contain elevated levels of nitrate and several other indicator parameters. Results of the leachate sampling yielded relatively high concentrations of many compounds, including ammonia and heavy metals such as lead and chromium.