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LK E/NFELOER <br /> Bright People.Right Solutions, <br /> appeared fairly low and may be the result of analytical compounds not analyzed for, <br /> such as semi-volatile compounds and/or other extractable compounds. <br /> Former Oil AST Area <br /> There were no detectable concentrations of TPH-D, BTEX compounds, MtBE, DIPE, <br /> EtBE, TAME, or TBA in any soil sampled at this location. The soil sample locations B-5, <br /> B-6, and B-7 are shown on Plate 1 . <br /> TPH-MO was detected in each of the shallow 1/2-foot bgs samples, with concentrations <br /> ranging from 41 mg/kg (B-6) to 240 mg/kg (B-5), and the 1-foot samples collected from <br /> B-6 and B-7, with concentrations ranging from 61 to 71 mg/kg, respectively. <br /> Based on the analytical data it appears the TPH-MO values have decreased with depth <br /> and it does not appear to be a significant issue at this time. However it should be noted <br /> that sandy soils may mask attenuation and migration of contaminants (e.g., <br /> contaminants may readily migrate through a given depth zone without analytical data <br /> illustrating this, and sandy soils in general do not retain contaminant as readily as finer <br /> soils such as silts and clays). If the client desires a greater level inquiry regarding this <br /> potential issue, deeper sampling is recommended. The reported concentrations of TPH- <br /> MO noted at these soil sample locations are below the commercial ESL of 2,500 mg/kg. <br /> RECOMMENDATIONS <br /> Kleinfelder has the following recommendations based on the results of this limited soil <br /> and groundwater assessment: <br /> 1) We recommend additional sampling and analyses of the shallow soil and <br /> groundwater in the vicinity of the former waste oil drum storage building to <br /> delineate the vertical and horizontal extent of the contamination. Additional <br /> soil samples should be collected from locations beyond the footprint already <br /> delineated in the northwest, south, and southeast directions. Sampling <br /> should be completed in general conformance with the California EPA, <br /> Regional Water Quality Control Board, Tri-Regional Board Staff <br /> Recommendations for Preliminary Investigations and Evaluations of <br /> Underground Tank Sites. <br /> 112884.1/ST010R366R Page 8 of 10 October 1, 2010 <br /> Copyright 2010 Kleinfelder Revision 1,dated November 22,2010 <br />