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a <br /> 275 Grantline Rd. <br /> Page 5 0f 7 <br /> This strata is underlain by approximately 4 feet of <br /> light to dark tan and brown, damp, slightly plastic clay; <br /> below this interval lies a moist gray-tan and tan-brown very <br /> fine-grained clayey sand. <br /> 2• Groundwater was encountered at a depth of 10.5 feet below <br /> surface grade in a tan-brown, very fine-grained clayey sand. <br /> This zone is assumed to be the top of the water shallow water <br /> table. The water level stabilized to a depth of 8.5 feet 5 <br /> hours after it was first encountered. <br /> 3. Petroleum hydrocarbons as oil and grease were detected in the <br /> excavated soils in the area of the removed waste oil tank. <br /> This contamination was <br /> staining. observed as dark grayish-green. <br /> 4. Petroleum hydrocarbons as gasoline were detected in one soil <br /> sample (SS-12) taken from the product line portion of the <br /> site. These analytical results indicate concentrations of TPH <br /> (as gasoline) below Corrective Action Levels (CAL) established <br /> by the Water Quality Control Board. <br /> 5. BTEX was detected in one shallow soil sample (SS-12) and is <br /> also below the CAL for BTEX. <br /> 6• oil and Grease was not detected in soil samples taken from <br /> the excavation area. <br /> 7. Analytical results of the pit water sample indicate <br /> concentrations of TPH (as gasoline) , BTEX, 1,2-Dichloroethane, <br /> and .oil and grease above CAL for groundwater. . <br /> CONCLUSIONS . <br /> 1. Based on the geological field data and analytical results it <br /> appears .that the vadose zone (saturated zone) has been <br /> impacted by hydrocarbon contamination as oil and grease. <br /> 2. This. hydrocarbon contamination is most likely due to leakage __- <br /> from-the removed waste oil tank. <br /> 3. <br /> ",,.,,,The extent. of the groundwater contamination outward from the <br /> tank .area is unknown at the present time <br /> 4 . Further sampling of the groundwater and a detailed groundwater <br /> gradient map is needed to define the limits and direction of <br /> the contaminant plume. This will also aid in the design of <br /> future groundwater remediation,. if it is required. <br /> There does .a y Y <br /> 4� 5' eraser to be is h drocarbon contamination in the <br /> product dispenser (pump island) .area or below the product <br />