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. Mr Michael Collins 2 September 17, 1992 Soil samples taken from the excavation had concentrations of total petroleum hydrocarbons as gasoline (TPH-G) ranging from non-detect (ND) to 8,900 parts per million (ppm); concentrations of benzene ranged from ND to 8 9 ppm; concentrations of toluene, ethylbenzene, and xylenes ranged from ND to 730 ppm, ethylene dibromide (EDB) ranged from ND to 0 007 ppm, and total lead concentrations were all ND The pump island samples had trace toluene concentrations ranging from 0 033 ppm and 0 049 ppm and ND for all other analytes Soil Vapor Survey The soil vapor survey was conducted on August 26, 1992 Prior to the start of the survey, the site was checked for underground utilities by Cruz Brothers Sub-surface Locators Any survey points falling in the path of an underground utility was moved to the nearest safe location The soil vapor survey was conducted by Environmental Control Associates and was supervised by a Canonie site engineer. The vapor probes were inserted using a hydraulic ram and advanced to the sampling depths The work plan had called for . samples to be taken at 9 and 15 feet, however, a hardpan layer was encountered and the deepest vapor probe was advanced 13 feet. Every effort was made to at least attain the 9 feet sample depth, but at two locations this was not possible Samples were taken using a charcoal tube connected to a constant flow sampling pump. A known volume of air was pumped through the tube. The tube was then capped and labeled with the site name, sample identification, depth, and time The sample tubes were then submitted to the mobile laboratory, extracted with methanol, and analyzed for TPH-G with a gas chromatograph/flame ionization detector (GC/FID) The reporting limit for TPH-G was 500 parts per billion volumetrically (PPBv) Following removal of the soil-vapor probe the hole was backfilled with neat cement grout. Results of Soil Vapor Survey A total of 13 soil vapor survey points were sampled at either one or two depths, depending on soil conditions The locations are shown in Figure 3. Because the hardpan made it difficult to sample deeper, an additional point (SG-13) located in the tank excavation area was sampled None of the samples showed detectable concentrations of TPH-G. A summary of soil vapor survey results are shown in Table 2 The analytical results are contained in Appendix A. These results indicate that if a source area exists, it is probably beneath the hardpan area Although TPH-G impacted soil was used to backfill the original tank . excavations, this potential source did not show up in the results of the soil gas survey points SG-2, SG-5, SG-8, and SG-13 which were within the limits of the excavation It appears from these results that the overall contamination of the backfill area is insignificant Cnm@mZ@Env1ronmenta1 PLIW 191-6341REPORTS1Co1hna1 RPT[September 17, 19921