Groundwater Monitoring Rainwater flows down through an uncapped landfill site and picks up substances from the decaying materials as it goes. Seeps are discussed in the Ivy Landfill chapter of this report. Groundwater is monitored for a list of 268 substances once a year, for a shorter list of 62 plus any substances found on the long list once a year at a different time. The 268 substances are those which are expected to be found at landfills. Twice a year sampling in done in wells around the perimeter of the landfill, beginning in 1990-91.
Findings change from sampling to sampling for many reasons, including the amount of rain.
The trend information over five years is currently being assembled in the Risk Assessment study. Groundwater Protection Standards are being developed by RSWA for contaminants founds at the landfill. Where background levels exceed MCLs, the background level is used. There is a high, natural level of lead the groundwater which could be from degradation of rock or the naturally occurring uranium in the region. Lead levels in nearby wells are not as high as found in test wells.