ARCHIVED REPORTS_XR0007370 CASE 2

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i IGroundwater samples were extracted from the five monitoring wells on July 21, 2004 to comply with quarterly reporting requirement The laboratory analyses report low I concentrations of TPH-diesel in the samples taken from MW-05 (85 µg/L) and from new well MW-08 (99 pg/L) All results of analyses from the other three monitor wells were below the laboratory's detection limit (<50 µg/L) for that analyte The results of analyses I for BTEX reported findings below the laboratory's detection limit (<0 50 µg/L) in all five wells The results of the complete laboratory analyses are presented in Table 4 Copies of the laboratory reports and chain-of-custody records are included in Appendix A I DISCUSSION & CONCLUSIONS IThe laboratory results for the soil sampling conducted during this period are � consistent with the findings presented to EHD in the April 4, 2003 report Low- concentration petroleum contamination appears to be present in the soil column under the site IThe findings for the groundwater analyses are also consistent for MW-04 and MW-06 as reported in previously submitted reports First Quarter 2003 Sampling Report, RMC Pacific Materials Kerlinger Aggregate Plant (August 19, 2003), Groundwater IMonitor Wells Second Quarter 2003 Sampling Report(January 8, 2004) and First Quarter 2004 Monitoring Report(March 19, 2004) The results for MW-05, however, differ from all previous reports with a TPH-diesel detection of 85 pg/L, slightly above the Ilaboratory's method detection limit (50 µg/L) The laboratory findings for groundwater analyses in the two new wells (MW-07 & MW-08) are ambiguous In June, the laboratory reported that the concentrations of TPH-diesel were below the detection limit but the samples contained extremely low, nearly identical, BTEX concentrations In the analyses of July's samples, the laboratory reported that the BTEX concentrations were below the detection limit but that a low concentration of TPH-diesel was present in the sample extracted from MW-08 RMC believes that the BTEX detections reported for June are suspect because no previous or subsequent findings of BTEX have been reported for any of the wells The contamination may have been introduced by the contractor's (Blaine Tech) ineffectively sanitizing the sampling equipment I The cumulative results for sampling and analyses for this reporting period appear to indicate that the local groundwater beneath the former asphalt plant has still not likely been affected by the petroleum contamination found in the upper surface soil layers IRMC Pacific Materials will continue to monitor the groundwater in the five wells in an effort to better understand the subsurface conditions • 5