Groundwater Impacts of Unlined Construction and Demolition Debris Landfilling

This report is based upon self-reported data from unlined construction and demolition (C&D) landfills. The Minnesota Pollution Control Agency (MPCA) prepared this report to help inform policy discussions and possible C&D landfill rule amendments. The Request for Comments for those amendments was published on October 1, 2018 (MPCA, 2018, p. 417). The groundwater-monitoring data on which this report is based is from wells installed in accordance with a 2005 guidance document drafted by the MPCA in consultation with C&D landfill operators ("Demolition Landfill Guidance Document" (DLGD) (MPCA, 2005). The 2005 DGLD did not change Minnesota rules or statutes; rather it established best practices based on what was then known about possible risks to groundwater. The DGLD was intended, in part, to provide data on possible effects of unlined C&D landfills on groundwater quality. Following the guidance, over time, most C&D landfills installed at least one upgradient and two downgradient groundwater-monitoring wells. This report contains conclusions based on the analysis of self-reported data from 43 C&D landfills with adequate groundwater monitoring, spanning eight calendar years from 2010 through 2017. Three contaminants of concern (COCs) were closely evaluated for the study: Arsenic, (As), Boron (B) and Manganese (Mn). As of 2014 these COCs, and in some cases other contaminants, were being commonly detected above intervention limits (ILs) and health thresholds (HT). The data from each of the 43 C&D landfills used for this study is located here: https://www.pca.state.mn.us/waste/construction-and-demolition-landfills-groundwater