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Mr Wade Broughton <br /> General Mills, Inc <br /> January 26, 1995 <br /> Page 5 <br /> The presence of TPH reported as diesel detected at a concentration of 410 ppm in the soil sample <br /> obtained trom soil boring SB-2 at a depth of 4 teet bsg appears to have been brought in as fill <br /> material According to General Mills, the sand backfill material placed in the upper 5-teet of the <br /> former tank basin, was imported trom ott-site by R & B & Sons of Tracy R & B & Sons was <br /> subcontracted by the excavating contractor, Pay Dirt Excavating of Stockton <br /> Review of historical depth to ground water data from the three monitoring wells indicate the highest <br /> depth to ground water measurement recorded at the site to date was 39 11 teet measured from the <br /> top of well casing MW-3 on February 23, 1994 This measurement is collected from approximately <br /> 0 5 feet bsg (which is where the soil sample depths were measured from during drilling) Utilizing <br /> this correction, the lowest stratigraphic soil sample reporting hydrocarbons above the laboratory's <br /> limits of detection (27 ppm TPH as diesel) was reported in the sample collected at 17 5 teet bsg <br /> This soil sample is 73 ppm less than the allowable 100 ppm TPH as diesel and approximately 7 5 feet <br /> stratigraphically higher than the allowable 25 teet bsg as presented in the County's letter dated <br /> April 28, 1994 Based on the cumulative ground water analytical results indicating that no analytes <br /> have been detected at or above the laboratory's reporting limits in soil samples collected below 17 5 <br /> bsg, site conditions are within the Criteria stated in the County's letter dated April 28, 1994, stating <br /> that "up to 100 ppm TPH-diesel could be lett in place at 25 tees below grade without posing a <br /> significant threat to groundwater", and that the site should be reconsidered for closure <br /> It is recommended that a copy of this report be forwarded to <br /> Ms Mary Meays Ms Elizabeth Thayer <br /> Environmental Health Division Calitornia Regional Water Quality Control <br /> Public Health Services Board, Central Valley Region <br /> San Joaquin County 3443 Routier Road <br /> Post Office Box 2009 Sacramento, California 95827-3098 <br /> Stockton, Calitornia 95201 <br /> Remarks/Signatures <br /> The recommendations contained in this report represent our professional opinions, and are based in <br /> part, on information supplied by the client These opinions are based on currently available <br /> information and are arrived at in accordance with currently accepted hydrogeologic and engineering <br /> practices at this time and location Other than this, no warranty is implied or intended <br />