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i I08 July 2004 AGE-NC Project No. 97-0343 Page 4of4 • 1,2-DCA was detected in the ground water samples collected from wells MW-3 and MW-4 at concentrations of 6.4 p.g/1 and 2.5 µg/l,respectively.No other fuel additives were detected at or above laboratory reporting limits in the ground water samples collected from the site. • The historically hydrocarbon-impacted well MW-1 was not purged or sampled during the March 2004 monitoring event due to the very low quantity of ground water in the well. However, wells MW-2 and MW-3 were sampled this quarter. TPH concentrations have Ideclined considerably in well MW-2 and declined to non detect concentrations in well MW-3 compared to the February 2002 sampling event which was the last time these wells were successfully sampled. ' • The lateral and vertical extent of the hydrocarbons-impacted ground water has been defined to be limited to an isolated dissolved mass above well MW-8, with the wells MW-4 to MW-7 and within the upper reaches of the upper water table,yet under depth of the dry well casings. The nature of the water table at the site is controlled by the rise and fall (season) of the water recharge collection basin, possible yet directly interconnected to the volume and frequency in which surface water filles or travels through the Stockton Diverting Cannel, located north of the site. The hydrocarbons-impacted soil at the water table may likely be directly impacting the fluctuating ground water as described above, therefore soil remediation should cause a direction reduction in the dissolved plume concentrations. 5.0. RECOMMENDATIONS Based on the findings of the environmental activities recounted in this report, AGE recommends continued quarterly monitoring of the on-site ground water monitoring wells. The next monitoring event was performed in June 2004. IG.O. LIMITATIONS Our professional services were performed using that degree of care and skill ordinarily exercised by environmental consultants practicing in this or similar localities. The findings were based upon analytical results provided by an independent laboratory.Evaluation of the hydrogeologic conditions at the site for the purpose of this investigation was made from a limited number of available data points(e.g.,ground water samples)and subsurface conditions may vary away from these data points. No other warranty,expressed or implied, is made as to the professional interpretations,opinions and recommendations contained in this report. I IAdvanced GeoEnviron mental,Inc. I