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` Quik Stop Station No. 039 February 17, 1999 Stockton, California Tank Closure Report 'e On October 29, 1998, Mr. K. Miller of the Stockton Fire Department and Ms. Letitia Briggs of the SJCPHS/EHD were onsite to observe the UST removal and transport activities. Upon removal, the USTs appeared to be in good condition with no noticeable holes and only minor rusting and pitting. The USTs were transported for disposal to the West Coast Equipment facility in Turlock, California. The excavated sandy backfill materiais from above and around the former USTs were stockpiled onsite (Figure 2), sampled by Horizon personnel, and then transported to the Forward Landfill (Forward) facility for disposal or recycling by Forward. Subsequent to the removal of the two USTs, soil samples were collected from depths between approximately 13 and 13'/2 feet below surface grade (bsg) from the north ends of each former UST (T -1-N-13 and T -2-N-13%2) and from the south ends of each former UST (T -1-S-13, T -2-S-13). The fill and turbine ports were located near the south ends of each former UST. The sampling locations are shown on the Site Plan (Figure 2). No soil samples were collected from beneath the product lines as the distance between the dispensers and the USTs was less than 20 feet. Soil sample D-1-3 was collected from approximately 3 feet beneath the south dispenser and soil sample D-2-3 was collected from approximately 3 feet beneath the north dispenser). Ms. Letitia Briggs of the SJCPHS/EHD was onsite to observe the soil sampling locations, and the sampling procedures. A 2 -inch diameter tank observation well was removed from the southeast corner of the former UST cavity to a depth of 16 feet bsg. An unidentified black clay -like substance was noted in the bottom of the casing. A sample of the clay -like substance (MW -SW) was collected for laboratory analysis at the direction of the SJC PHS/EHD inspector Mr. Michael Infurna Jr. SJC PHS/EHD records indicate the tank observation well was installed in 1981. Excavated Soil Soil samples were collected from the stockpiled soil (approximately 200 cubic yards) excavated from around and beneath the former USTs. One sample sleeve was collected for each approximately 25 cubic yards of soil at the locations shown on Figure 2. The laboratory composited four individual soil samples to represent approximately 100 cubic yards (SP-1-A,B,C,D and SP-2-A,B,C,D) per composited sample. Soil excavated from the replacement UST excavation was used to backfill the former UST excavation. On November 17, 1998, four confirmation soil samples were collected from this soil by Horizon personnel and composited by the laboratory (BF-1-A,B,C,D). Analytical Methods and Results All of the .soil samples were prepared, chilled, and transported `under chain -of -custody (COC) protocol to Kiff Analytical (Kiff), a State -certified laboratory in Davis, California (Certification No. 2236). The requested analyses included: total petroleum hydrocarbons as 7039-1 l.tcr 2 HORIZON ENVIRONMENTAL INC.