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f.\pwjects\5137\rydestk.mp <br /> 3.0 FINDINGS <br /> 3.1 Initial Surface Sampling <br /> On December 6, 1990, a representative from ESE collected two soil samples from the <br /> heavily stained surface soil beneath the tank, as shown on Figure 1 - Site Plan Before <br /> Excavation. These ear nples represent soil containing the highest concentrations of waste <br /> oil. The samples were composited into one an(, analyzed for a variety of possible waste oil <br /> ' constituents, in accordance with Central Valley Regional Water Quality Control Board <br /> (RWQCB) guidelines. The analytical results are presented in Table 1 - Summary of Soil <br /> Sampling Analytical Results. The most prominent constituents found were Oil and Grease <br /> at 11,000 mg/kg and Total Petroleum Hydrocarbons as diesel (TPHd) at 3,000 mg/kg. <br /> Other petroleum hydrocarbon constituents, semivolatile organics, and metals were detected <br /> at concentrations below California Department of Health Services (DHS) hazardous waste <br /> levels. No volatile halogenated hydrocarbons were detected during this sample analysis. <br /> The tank was removed from the site by JOTCO, a licensed hazardous waste hauler, to the <br /> ' Erickson Environmental recycling facility in Richmond, CA on December 13, 1990. <br /> ' 3.2 Hand-Auger Sampling <br /> On December 27, 1990, a representative of ESE hand-augered to depths of 6.5 and 7.5 <br /> feet below grade in two locations beneath the former tank (Borings W and E on Figure <br /> 1). The boring logs, contained in Appendix A, show that the clay and clayey silt soil found <br /> was generally oily with a strong hydrocarbon odor. One soil sample was taken from boring <br /> E at a depth of 6 feet to assess the vertical extent of the hydrocarbons. Table 1 shows that <br /> this sample contained 110 mg/kg Oil and Grease. <br /> 3.3 Initial Excavation and Soil Borings <br /> The initial soil sampling on December 27 established that the vertical extent of <br /> hydrocarbons in the soil was at least 6 feet, and the lateral extent had not yet been defined. <br /> ESE recommended that a backhoe be used to excavate the soil containing hydrocarbons. <br /> ' 4 <br />