To evaluate whether VOCs are migrating out of the landfills into the vadose zone, a soil vapor survey of the soil beneath the landfill bases was performed. Permanent vapor monitoring probes were installed and then sampled twice for VOCs. Groundwater beneath the landfills has been impactd by VOCs, namely TCE, DCE, and toluene.

This Additional Site Characterization Work Plan presents a strategy for collecting site characterization information at the closed Maricopa County Cave Creek Landfill to support ongoing remedial action planning for trichloroethene-impacted groundwater underlying the site. The Work Plan supplements previous remedial investigation work plans prepared to characterize the nature and extent of site contamination.

A majority of the work performed by ADEQ's Nonpoint Source Program is funded by Clean Water Act grants, awarded by the U.S. Environmental Protection Agency which requires States to report annually on progress in meeting the schedule of milestones contained in their nonpoint source management plans, and report reductions in nonpoint source pollutant loadings and improvement in water quality resulting from program implementation.