FIELD DOCUMENTS_CASE 1 - Laserfiche WebLink

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i The previous soil sampling data in 1998-1999 showed that there was some minor leakage along the pipeline with the' most elevated levels at the pipeline sample at 60 feet from the original dispenser island (1998 Pipeline Sample at 60' from the dispenser). Very little contaminant was detected.in the other soil samples from the tank pit, pipeline and under the dispensers in 1998. Soil sample B-3 @ 3' collected from the former UST piping trench (near the vicinity of the original Pipeline Sample at 60' sample location) showed that only slight soil vapor and TPHD at 7.0 Mg/kg was detected at that location. Contaminated soil from the UST closure project was stockpiled at that time and had apparently been treated at the surface by aeration while waiting to be stockpiled, again while being placed into a common stockpile and then again when all soil was returned to the UST excavation, pipeline trench and dispenser island excavations. On the basis of the field observations and chemical soil results from 1998 and this 'study, there does not appear to be a contaminant presence along the former dispenser island area, pipeline trench or below the former tank pit. The laboratory noted that the very low TPHD results are noted as higher that those typical of TPHD and are interpreted as either matrix interference or degraded remnants of residual fuel. 7.0 Conclusions and Recommendations Wright collected 12 soil samples from along the former fuel pipeline and the underground storage tank pit. The purpose of the soil sampling and analyses was to ascertain the presence of residual fuel compounds. The former pipeline and former underground storage tank pit were located using ground penetrating radar and a review of historic aerial photographs. Six exploratory borings were advanced to collect soil samples in native soil below dispenser island area, pipeline trench and/or tank pit backfill. Native soils consisted of interbedded clayey sand, sandy silt and sand with gravel. Groundwater was not encountered in any shallow boring or at the maximum depth of the boring B-6 of 30 feet. Chemical analyses showed that TPHG, BTEX, fuel oxygenates, 1,2-Dichloroethane, Ethylene Dibromide, Ethanol and Methanol were not detected in any sample. Very low levels of TPHD were detected in the pipeline samples and one very low detection of TPHD in tank pit backfill. Soil samples collected below the tank pit in native soil showed that no contaminants were detected. The presence of the very low TPHD is interpreted as either residual fuel or matrix interferences. The laboratory noted that the TPHD detected hydrocarbons were higher boiling than typical Diesel fuel. In our opinion the chemical data do not show a significant contaminant problem. The excavation and handling of stockpiled contaminated soil in 1.998-1999 had addressed the problem. While a groundwater sample was desired by EHD, contaminants were not detected in soil samples from 15 to 30 feet below the backfilled tank pit. Given the estimated depth to groundwater (estimated over 70 feet) and lack of contaminant presence detected in soil samples, a groundwater threat is not present on the basis of these data. Page 5 of 7