ARCHIVED REPORTS XR0000211 - Laserfiche WebLink

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SECTIOMEIG H T Soil concentrations at the site were compared to EPA Region IX PRGs for industrial exposures Concentrations of CDCs in surface soil (less than 15 feet bgs) were significantly lower than industrial PRGs PRGs consider ingestion, dermal, and inhalation exposures of VOCs and particulates The results of this risk analysis indicate that upon potential exposure to chemicals in groundwater and soil and from chemicals moving from soul to other media at the site there are insignificant carcinogenic ' and noncarcinogenic risks C e, below a carcinogenic risk range of 10-'to 10" and a hazard index of 1) Conservative fate and transport modeling indicated that potential concentrations of chemicals of concern in groundwater would not cause significant impacts to human health It should be restated that the scenarios in this risk assessment used a combination of site-specific data and conservative ' assumptions that represent the "high-end" exposure and more than likely overestimates the actual total cancer risk given the exposure and behavior patterns assumed for this assessment The concentrations in the groundwater (at an on-site downgradient well) meets Basin Plan objectives within a distance of approximately 200 feet from the original source The groundwater gradient is fairly flat at the site (0 002 foot per foot) and was modeled to be at extremely low ' concentrations using conservative parameters at hypothetical wells Municipal water wells in the area are screened at much greater depths, 500 feet bgs, and the wells at the site have demonstrated that the concentrations are not leaching downwards More than 12 years of groundwater monitoring data have been collected which have venfied both the limited area of shallow groundwater that has been affected and the continuing decline in residual concentrations over time in that limited area 1 � � ® T%Iggr973008NA%STOCKTONIREPORT%SHOREPNI DOO&FEB-OM7300BNAISNA 8-2