ARCHIVED REPORTS_XR0007344 CASE 2

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i After each well sampling, the hand bailer was completely dismantled and thoroughly cleaned using a laboratory-grade detergent (Alconox) and scrub brush, then triple rinsed with domestic and distilled water prior to use in the next baring I IRESULTS OF PRELIMINARY ANALYSES All soil and water samples were analyzed for TEPH- Diesel (EPA method 8015M) The I laboratory results for initial analyses are presented in Table 1 Laboratory analyses performed on the soil samples indicate that low-level petroleum contamination extends down to the groundwater table in each of the borings The highest concentration of soil contamination (1,400 ppm) was found in BH-1, at a depth of 20 feet bsg Beneath that depth the concentration of diesel hydrocarbons dropped considerably, to a maximum of 16 ppm In BH-2, the highest concentration (82 ppm) came from a soil sample taken at 124 feet bsg, however all other analytical results from that boring were at a much lower concentration The analyses of the soil samples from the other three borings indicate that the diesel concentrations ranged from levels of non-detect to a maximum of less than 13 ppm In bonngs BH-I through BH-4 near the former asphalt plant the groundwater diesel concentrations in sequential order were 720gg/L, 120gg/L, 120gg/L and 72 gg/L respectively In the boring BH-5 installed near the former 7,000-gallon diesel UST the concentration was 590gg/L Copies of the laboratory reports and chain-of- custody records are included in Appendix A WELL DEVELOPMENT& SECONDARY SAMPLING On December 11, 2002 an attempt was made by RMCPMI environmental department personnel to develop the three wells in order to improve hydraulic continuity with the native formation An airlift method was used, but the attempt was not successful due to the very low ratio of water level in each well casing compared to total well depth RMCPMI then contacted a professional well company (Gregg Drilling Inc ) to perform the work and on January 8, 2003 the wells were successfully developed I Subsequent to the well development a new set of groundwater samples were taken from the three wells on February 18, 2003 by Blaine Tech Services, Inc No evidence of immiscible liquid was present on the water tape,the sampling bailer or the extraction pump Due to the fact I that February 18th was a holiday the groundwater samples were stored over night on ice and then transported to STL for analysis the following morning Proper charn-of-custody protocol was maintained at all times I DISCUSSION Initial laboratory analyses performed on the groundwater samples extracted from the five bonngs appeared to indicate that diesel contamination had reached the local water table IHowever, the laboratory results from the second set of field analyses contradict that hypothesis as they indicate that no diesel contamination exists in the groundwater A possible explanation I I