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.

This study, and the resulting transportation plan, is funded through ADOT’s Planning Assistance for Rural Areas (PARA) program. ADOT and the Town of Colorado City have retained the consultant team of Wilbur Smith Associates to conduct the study under the oversight and direction of a Technical Advisory Committee (TAC) that includes members from the Town of Colorado City; adjacent Hildale City, Utah; Mohave County; the Arizona Department of Transportation Multimodal Planning Division; the ADOT Flagstaff District Engineer’s office; and other interested parties.

This study involved the review of 417 ADEQ LUST site files and compilation of relevant data from 323 of these sites into an electronic database. It also involved the collection and analysis of over 700 supplemental groundwater samples, the assessment of aquifer flow properties from 32 wells at 11 sites, and more detailed characterization at six LUST sites representative of a range of conditions at AZ LUST facilities. In addition, over 300 groundwater level measurements were performed and 175 monitoring wells were re-surveyed in order to assess errors in standard practice and their impact on groundwater flow direction determination. An empirical analysis of groundwater impacts at AZ LUST sites was conducted using these data sets, with emphasis on identifying relationships between site conditions (e.g., geology, depth-to-groundwater, etc.) and groundwater impacts. Finally, a combined theoretical-spatial (GIS) analysis was performed to identify LUST scenarios posing the greatest threats to use of groundwater resources.

From May 2005 to June 2005, the Arizona Department of Environmental Quality conducted a study, Potable Well Sampling Task 4.0, to determine if the chromium and chromium VI plume due to the discharge of the Pacific Gas and Electronic Topock Compressor Station has migrated under the Colorado River and impacted water supplies in Arizona. The ADEQ investigated the total chromium and hexavalent chromium (chromium VI) concentrations in (1) public water supply wells, (2) combined industrial and domestic water supply wells, and (3) private domestic water supply wells at Topock and Golden Shores, Arizona. The communities of Topock and Golden Shores have expressed their concerns regarding the findings. Thus, the ADEQ requested the Arizona Department of Health Services to evaluate the potential health effects of exposure to well water contaminated with chromium.

In March 2004, the U.S. Environmental Protection Agency requested information on efforts to monitor and protect children from exposure to lead in drinking water at schools. The Arizona Department of Health Services reviewed the state lead poisoning registry, and analyzed drinking water samples from 45 randomly selected schools. The Office of Environmental Health provided this consultation to help document our findings and supplement our response to the EPA. This work was also undertaken to help provide useful information should hazardous waste sites be discovered in the future near these schools. We also wanted to apply the ATSDR health assessment process in support of state and federal efforts to protect the health of children.

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.

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.