FIELD DOCUMENTS - Laserfiche WebLink

Home Browse Search

E On December 19,,1994,a agger excavator performed additional excavation downward and toward the south, according to the recommendation of Mr. Snavely. This recommendation was the result of review of the analyses of the samples collected at 11.0 ft, and the information provided by diesel fuel staining within the excavation. Sample TK04-829-01-D1U1-SO-17.0 was collected on December 19 and submitted to CLS for TPH-D and BTXE analyses. The results of analyses showed 2400 mg/kg TPH- D,and 0.042 mg/kg for xylene of the BTXE analytes. Noting that the TPH-D concentration for the soil sample collected at a depth of 17.0 feet was fifty percent greater than the value for the sample collected at depth of 11.0 feet, an investigation was initiated to learn more about causes for the apparent increase in concentration with increasing depth. We determined that the analytical laboratory (CLS) collected a 5.0 gram sample from our sample tube without regard to the fact that the tube contained a stratified composite sample. The stratified composite consisted of several strata collected from several locations within the back hoe bucket to represent both the stained and unstained portions of the soil within the bucket. On December 27, 1994,CLS was asked to homogenize the remaining sample (all present except for the five grams used in the initial analysis) and perform a second TPH-D analysis. (A second BTXE analysis was not requested because of the time elapsed since sample collection.) The result of the re-analysis of sample TK04-829-01-D1U1-SO-17.0) showed 990 mg/kg TPH-D. In order to improve our understanding of the amount of diesel fuel contamination remaining in the tank removal excavation, additional soil samples were collected from the bottom of the excavation on December 21, 1994. Sample TK05-829-01-D1U1-SO-17.0 was analyzed by CLS and showed 58.0 mg/kg TPH-D and ND for BTXE. Sample TK06- 829-01-D1U1-SO-17.0 was analyzed by GTEL Environmental Laboratories,Inc.,in Concord,Ca.,and showed 930 mg/kg TPH-D and ND for BTXE. Sample TK07-829-01- D1U1-SO-17.0 was submitted to CLS and showed 630 mg/kg for TPH-D and 0.033 mg/kg xylene of the BTXE analyte. The GTEL sample analyses (not a split sample)was performed to provide an informal check against the CLS analyical results. Please note the attached table"Summary of 829-DlU1 Tank Closure Soil Sample Analyses Results". The at the 829-DlU1 closure site "VicMat below the surface rsonal communication withrid and Mike Taffet of the Lawrence Livermore National Laboratory Environmental Protection Department, Environmental Restoration Division. This information is based on monitoring well data.)