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~ Subsurface investigation Results <br /> a� 6131 Pacific Ave., Stockton, cA. <br /> 4 Aegis Project No. 90.020 <br /> Page 12 <br /> w— <br /> 3 ? CiR UNn N TE CONDI' IOIr•8 <br /> Soil boring B-1 was dizlled to determine the depth to first <br /> groundwater. A saturated horizon was encountered at approximately <br /> 53 feet below grade. <br /> 3.3 PATROLEUM YDROCARSONiS IN BAIL <br /> 'J A total of 28 soil samples were submitted to Sequoia Analytical <br /> w Lab and analyzed for petroleum hydrocarbons. The test methods <br /> applied by Sequoia were EPA 5030/8015/8020 analyzi g for <br /> �r.1 low/medium boiling point hydrocarbons, benzene, toluene, <br /> s ethylbenzene, xylenes and total lead. The results of the soil <br /> samples are summarized in Table 2. The certified laboratory <br /> a reports are .ontained in Appendix C. The following subsections <br /> (: present the results of analyses from the existing and proposed <br /> underground storage tank locations. <br /> is <br /> 3.4 PETROLEUM YDROCARSONo IN &OIL: OR CINA AI?K BASIN <br /> Soil borings B2 through B5 were drilled adjacent to tt:z existing <br /> tank basin-to depths of 46 to 51 feet. The purpose of soil <br /> borings B2 through B5 was to ascertain the depth. to which <br /> petroleum hydrocarbons in soil had migrated and to <br /> antif <br /> levels of petroleum hydrocarbons in the native soilsubeneaththe the <br /> tank basin. Thirteen soil samples recovered from soil borings <br /> drilled adjacent to the original tank basin were submitted for <br /> analysis. Eleven of the thirteen. soil samples contained petroleum <br /> hydrocarbons above detection limits. The highest concentration of <br /> M' petroleum hydrocarbons were found in soil.boring.B3. Levels of <br /> total petroleum hydrocarbons (TPH) ranged from below detection <br /> limits to 17,000 parts per million (ppm) (Sample B/3 from 151) . <br /> Soil sarple B3/8 collected from 5o feet below grade contained <br /> tv3 9,700 ppm TPH. Gasoline odors and PID readings were noted as <br /> strong in B-3, and mild in B-2 and B-4. <br /> a <br /> 3.5 PETROLEUM FlYDROCARBONS IN BOIL: PROPOSED NEA TANK LOCATION <br /> f � Soil borings B9 through B14 were drilled in the area of the <br /> replacement .tank basin to confirm soil conditions (figure 5) . <br /> Nine soil samples recovered from soil borings drilled at the <br /> location of the replacement tanks were submitted for analysis. As <br /> � } shown in table 2, petroleum hydrocarbons were not detected from <br /> the recovered soil samples. Gasoline odors were not detected in <br /> soil samples recovered from soil boring B9 through 814. <br /> x <br /> L <br /> W <br />