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19 October 2012 AGE-NC Project No. 97-0312 Page 2 of 22 The Modesto, Riverbank, Turlock Lake Formations and overlying recent alluvium are the L principal source of domestic groundwater in the 13,500-square mile San Joaquin Valley Groundwater Basin (Basin 5-22). Groundwater in the area of the Cherokee Truck Stop site is considered to be of beneficial use. V 2.2. RECEPTOR SURVEY Typically, groundwater would represent the migration medium for contaminants over significant horizontal distances. However, sites located in up-gradient or cross-gradient directions from the subject property are not likely to be negatively impacted by the subject property. In addition, first encountered groundwater is not used for drinking or irrigation, V although all groundwater in the State of California is considered to be of potential beneficial use. Drinking water at and near the site is supplied by private wells. Two on-site domestic wells (DW-1 Large and DW-2 Small -ABANDONED)were identified during a sensitive receptor survey conducted during 1999; DW-1 is located approximately 450 feet northeast and 6w DW-2 was located approximately 250 feet southwest, from the former UST system. DW-2 reportedly has been out of service since 1978 due to sand infiltration problems and was abandoned in October2000.Groundwater samples are collected and analyzed periodically from well DW-1; to date analytical results have been non-detect. In addition to on-site well DW-1, ten additional private wells and one public well were identified within a 2,000-foot radius of the site; the nearest off-site well is approximately 220 feet from the site. Based on the lateral extent of impacted groundwater at the site, it is unlikely for off-site wells to be contaminated by impacted groundwater from the site. The Property utilizes two septic systems, one is located approximately 90 feet east of the rimt- former UST system and the second system is located toward the front of the property, near 6w the office building, approximately 250 feet west of the former UST system. Based on the lateral extent of impacted soil and groundwater, there is a low potential for the septic systems to act as conduits for subsurface migration of impacted groundwater. V The nearest surface water feature to the site is the Stockton Diverting Canal, located approximately 2,300 feet south-southwest of the site. This basin is drained primarily by the San Joaquin River. It is unlikely that water in the Stockton Diverting Canal is contaminated by impacted groundwater from the site based on its distance and direction (up-gradient) from the site. r V Advanced GeoEnvironmental,Inc.