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i 1 Tank Abandonment Site Assessment Work Plan NuStar Stockton Terminal Stockton, CA Page Three PL-2, etc. were advanced to assess the product piping. Borings designated TP-1 and TP-2 were advanced to collect soil samples from the tank pit area. During the investigation standard practices and procedures for field sampling as outlined in Publication SW-846, Second Edition, United States Environmental Protection Agency were followed. The work was performed under the direct supervision of a California Professional Geologist. A direct push geoprobe drilling rig and hand auguring was utilized for the advancement of the soil borings. Pre-cleaned drilling equipment was used throughout the drilling operation to prevent potential cross contamination. SOIL SAMPLING A total of 26 undisturbed soil samples were collected for selected chemical analyses. The soil samples were collected using either a 6-inch long, 1.5-inch O. D. drive sampler with 6-inch stainless steel sample tubes or a 36-inch PVC sample sleeve placed inside the Geoprobe sampling device. The steel sample tubes were sealed with Teflon tape and PVC caps. A six-inch section of the PVC sample tube was removed and sealed with PVC caps. An adjacent section of the sample tube/sleeve was used for OVA evaluation and lithologic characterization. GROUND WATER SAMPLING Ground water was not encountered in the soil borings adjacent to the tank pit, therefore no ground water samples were collected for analytical testing. ANALYTICAL TESTING Soil samples were submitted to a State certified laboratory for analysis by California DHS modified EPA Method 8015 TPH gasoline and diesel carbon chain(C4 to C36) and by EPA Method 8260B for Volatile Organic Compounds (VOC's) and for total lead by method 7421(6010)in accordance with the procedures outlined in Table 2"Recommended Minimum Verification Analyses For Underground Storage Tank Investigations." A summary of the TPH test results is attached as Table 1. A total of twenty-six samples were collected for petroleum testing. Analytical testing of the soil samples reported detectable total petroleum hydrocarbons (TPH) as gasoline in 5 of the samples at concentrations ranging up to 140 mg/Kg in samples collected from boring TP2@15' and PL7@5'. TPH as diesel was reported in 4 of the samples at concentrations ranging up to 410 mg/Kg in the sample collected from boring PL7@5'. TPH as motor oil was reported in 5 of the samples at WGR Southwest, Inc. 11021 Winners Circle, Suite 101 - Los Alamitos, CA 90720 - (562) 799-8510