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02 January 2015 AGE Project No. 13-2557 Page 2 of 7 The Modesto, Riverbank, and Turlock Lake Formations and overlying recent alluvium are the principal source of domestic ground water in the 13,500-square-mile San Joaquin Valley Ground Water Basin (Basin 5-22). This basin is drained primarily by the San Joaquin River. Based on depth to groundwater measurements collected in 2009 at surrounding sites (65 East Eleventh Street and 95 West Eleventh Street), AGE estimates depth to groundwater at the site is between approximately 13 and 18 feet bsg and the estimated groundwater flow direction is generally toward the north. 2.2. UNDERGROUND STORAGE TANK REMOVAL On 01 May 2014, one 350-gallon UST was removed from the site. The UST was located along the western border of the property, beneath the City of Tracy sidewalk located on the east side of Holly Drive. The following is a brief summary of the tank removal activities: On 29 April 2014, AGE exposed the area of the UST at the edge of the site and determined the City of Tracy sidewalk covered the UST completely. AGE removed the sidewalk concrete. Initially, the soil over the UST was excavated from the site with a backhoe and stockpiled on-site. The UST was inspected to evaluate residual petroleum waste and was determined to be 75% full of liquids and semi-solids. At the request of the City of Tracy, the excavation was temporarily backfilled until a waste disposal company could be contracted. On 01 May 2014, the UST excavation was re-established and additional soil over the UST was removed and stockpiled. Advanced Chemical Transport (ACT) provided a heated pressure washer, vacuum truck and support services to evacuate the semi-solids from the UST and triple rinse the inside of the tank. A black, oil-like residue with sediment and possibly waste fuels was present at the lower portion of the UST. After rinsing, approximately 30 lbs. of dry ice then applied to the UST. The lower explosive limit (LEL) and free oxygen was simultaneously measured to evaluate the risk of fire prior to UST handling and removal. The tank and associated piping were removed, transported and properly disposed of by West Coast Equipment of Turlock, California. One (1) soil sample was collected from the base of the UST excavation at 9 feet bsg and two (2) soil samples were collected and composited from the excavated stockpiled soil. The following is a summary of results: Total petroleum hydrocarbons as gasoline (TPH-g) were detected in both the excavation bottom (Tank#1-9ft) and stockpile sample (SP1&2) at concentrations of 35.2 milligrams per kilogram (mg/kg) and 42.3 mg/kg. Advanced GeoEnvironmental Inc.