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02 May 2013 AGE-NC Project No. 04-1168 Page 2 of 10 plain extending from the Tehachapi Mountains in the south to the Klamath Mountains in the north. The western and eastern boundaries of this province are comprised of the California Coast Range and the Sierra Nevada Mountains, respectively. Based on a General Soil Map from the San Joaquin County Soil Survey, published by the United States Department of Agriculture Soil Conservation Service in 1992, the site area is described as being within the Jacktone-Urban Land Complex (JULC). The JULC soils are described as somewhat poorly drained and derived from mixed rock sources. Based upon data obtained from San Joaquin County Flood Control District and Water Conservation District Lines of Equal Elevation of Groundwater Fall 2011 map, the prevailing groundwater flow direction in the vicinity of the site is estimated to be north- northeast.Additionally, based on groundwater elevation data collected during the previous monitoring event in December 2012, the groundwater flow direction on-site is generally towards the southwest to southeast. The Mormon Slough and McCleod Lake are the nearest surface water features to the property, located greater than one mile northwest of the site. 2.2. UNDERGROUND STORAGE TANK REMOVAL According to records on file with the San Joaquin County Environmental Health Department(SJCEHD), four underground storage tanks (USTs)were formerly located on the property. Three of the USTs were located in a common excavation,west of the on-site building; a fourth UST, presumably used for waste oil, was located south (behind) the on-site building. In 1998, the four USTs were removed by Paydirt Excavation. The USTs had been out of commission and empty at the time of removal. Soil samples were collected from the UST excavation,former piping areas and dispenser island area. Petroleum hydrocarbons were not detected in soil samples collected at the time of removal. 2.3. SITE INVESTIGATIONS The following is a brief summary of the site assessment investigations conducted at the site to date: • July 2004 -Three soil probe borings (131 though 133) were advanced at the site utilizing a van-mounted Geoprobe 5400. Boring B1 was advanced in the formertank pit to a depth of approximately 30 feet bsg at which point probe advancement ceased due to subsurface refusal as the result of pea gravel falling into the boring Advanced GeoEnvironmental,Inc.