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Hit NICK-fIERNER Mr. Charles Leubner 20 January 1997 Page 6 Excavation and Stockpile Sampling Ms. Letiticia Briggs was the San Joaquin County Environmental Health Division Inspector in attendance during the removal of the gasoline tanks. A representative of the Stockton City Fire Department was also in attendance. Samples from the excavation floor and stockpiles were collected by Mr. Noel Lerner of Helmick & Lerner Inc. and were delivered to ExcelChem Environmental Labs in Roseville, California for analysis. The samples were kept chilled in an ice chest during transport to the laboratory and were accompanied by chain -of custody forms. The gasoline tank excavation had only a small amount of water at the bottom of the excavation when the tanks were removed and no stains indicative of leaks were evident. No holes were evident in the tanks when they were inspected after they were removed from the excavation. Sampling procedures for collection of soil from the excavation floor and the stockpiled soil removed from the excavation followed those described above for sampling conducted during removal of the diesel tanks. The location of the samples and the depths from which they were collected are shown on Figure 4. Analytical Results Table 2 summarizes the results of the laboratory analyses of samples collected from the excavation and soil stockpile. All samples were analyzed for Total Petroleum Hydrocarbons as Gasoline (TPH-G) by EPA Method 8015 modified, and benzene, toluene, ethylbenzene and xylenes (BTEX) and MBTE by EPA Method 8020. The samples for the tank that had previously contained leaded gasoline (T1) and the composited stockpile samples were also analyzed for total lead (EPA Method Series 7000). Tank Excavation Samples Gasoline hydrocarbons were detected by laboratory analysis only in one sample from the tank excavation (Sample 635), although field screening indicated elevated organic vapors in the headspace for Sample 633 as well. The excavation was backfilled without overexcavating soil near Sample 635. Stockpile Samples Neither gasoline hydrocarbons nor BTEX constituents were detected above their respective method detection limits of 1.0 mg/Kg and 5 ug/Kg in the two composited samples analyzed from the gasoline tank excavation stockpile. Lead concentrations in all the samples that were analyzed ranged from 4.5 to 6.8 mg/Kg. This level is below the TTLC criterion of 1,000 mg/Kg, and even if all of this lead were in a soluble form, the STLC criterion of 5.0 mg/L could not be exceeded.