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404 WEST FREMONT STREET ' WKA No 1628 08 February 11, 1997 Page 2 The submersible pump was cleaned with a solution of Liqu►-nox and water prior to purging each well to minimize the potential for crass-contamination All water removed during sampling and purging operations was placed in sealed and labeled 55-gallon drums and stored on site Analysts of water samples MM2, MW3 and MW6 revealed no detectable concentrations of TPH or BTEX The one exception for the above four wells was a trace concentration of Xylene reported to well MM6 Concentrations of petroleum hydrocarbons were detected in the water samples from wells MW1, MW4 and MW5 Review of hustonc data reveals continued decreasing TPH as gasoline concentrations in MW 1, MW4 and MW5 A summary of analytical results for groundwater samples obtained from the six on-site and one off-site morutonng wells are included as Tables 1 and 2 Complete analytical reports and chain-of-custody documentation are included to the appendix This most recent groundwater measuring event indicated that the flow direction had changed from previous measurements Prior to this sampling event, TPH as gasoline concentrations had been steadily increasing in both MW4 and MW5 while decreasing in MW I Thus earlier trend seemed to indicate that the plume of contamination was moving off-site in a northwesterly direction even though the calculated groundwater flow direction had previously been toward the northeast With a reported reversal in the groundwater flow direction, and decreasing gasoline concentrations in MW4 and MM5, the plume of contamunatuon may be moving back toward the tank pit Because only one measuring event has shown this change in flow direction, however, not enough data exists to confirm a long-term change In addition to the TPH/BTEX analyses, SJCPHS requested that we analyze the local groundwater for Alkalinity, Hardness, Nitrates and Dissolved Iron to establish a baseline of data related to naturally occurring bioactivity which may degrade the plume of contamination Concentrations for each of these constituents appeared very consistent with a notable variation only to Nitrates While MW 1,_MW3,MW4 and MWS revealed Nutrate_as�Iti concentrations,rangung from<0 05 0 2 mg/L, SMW2, MW2 and MW6 reported Nitrate and N concentrations of 6 9 mg/L, 14 mg/L and 27 mg/L, respectively • WALLACE•KUHL Rec,,dpap, fir ASSOCIATES INC