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Underground Storage Tank Removal Report Page 2 320 W. CENTER STREET March 25, 2011 WKA No. 9041.011' 2.0 UST REMOVAL ACTIVATES An Application for Underground Storage Tank Closure Permit was submitted and approved by the San Joaquin County Environmental Health Department. (SJCEHD). A copy of the approved UST Closure Permit is provided in Appendix A. On March 4, 2011, Scott Johnson with Johnson Petroleum Construction was on site to remove the UST. Mr. Muniappa Naidu, an inspector from SJCEHD, was present to observe the UST removal and soil sampling activities. The overburden material was excavated using a backhoe and stockpiled on plastic shecting (Refer to Figure 3). The top of the UST was encountered at an approximate depth of 2 feet below ground surface (bgs). After the tank was exposed the remaining product in the tank was removed and the tank was triple rinsed using water pressure. Approximately 500 gallons of liquid waste was generated including the reinstate and the remaining product. The liquid waste was removed using a vacuum truck. The tank was packed with dry ice and the backhoe was used to remove it from the pit following determination that the UST interior atmosphere was below the lower explosive limit (LEL) and that oxygen had dropped to 4 percent. The atmosphere inside the UST was monitored for lower explosive levels (LEL) and oxygen content using a combustible gas meter. The singled walled, approximately 2.000 gallon UST was observed to be approximately 5 feet in diameter and 10 feet in length. Multiple small holes were observed in the bottom of the tank. Black oily staining was observed in soil at the bottom and eastern sidewall of the pit. Approximately a one—foot thickness of visually stained soil was excavated liom the bottom of the tank pit. Visually stained soil was also excavated from the eastern sidewall. The visually stained excavated soil was stockpiled on plastic sheeting in a separate pile near the overburden stockpile (Refer to Figure 3). ` Groundwater was not encountered during UST removal activities. .. 2.1 Soil Sampling Soil sampling was conducted under the direction of Mr. Naidu. Following over excavation the backhoe was used to obtain confirmation soil samples (S-2 and S-3) from exposed native soil in the bottom of the excavation, at an approximate depth of 8 feet bgs (approximately 1-foot beneath the bottom of the former UST). One sample was collected at each end (east and west) of the excavation. The soil samples were obtained by driving a clean, 2-inch diameter by 6-inch long brass sample tube into the undisturbed soil contained %�ithin the backhoe bucket. �`�