SITE INFORMATION AND CORRESPONDENCE

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page 2 26500 Nowell Road In February 1996 five soil borings were advanced on site (MW-1, MW-2, MW-3, SB-A1 & SB-A2), three of which were completed as monitoring wells. Soil boring SB-A2, which was located near SB-A in the former tank pit area, was advanced to the greatest depth, to 33 feet bsg. Analytical results of the soil samples collected from SB-A2 evidenced 5,500 ppm TPHg and 22 ppm benzene in the 16 foot bsg sample, and .72 ppm TPHg and .0089 ppm benzene in the 33 foot bsg sample. A grab water sample was not collected for analysis. One of the groundwater monitoring wells was completed to 20 feet bsg (MW-1), the other two were completed to 18 feet bsg. Groundwater monitoring events have occurred five times at this site, between February 1996 and July 1997. Results have evidenced intermittent low levels of TPHg and BTEX. At the first monitoring event in February 1996, MW-1 and MW-2 both had detectable levels of TPHg and benzene, toluene, ethylbenzene and xylene (BTEX). MW-1 had .5 ppb xylene at the August 1996 sampling event. MW-2 had 51 ppb TPHg and MW-3 had 62 ppb TPHg at the March 1997 sampling event. Analysis for methyl tertiary butyl ether(MTBE) by EPA Method 8020 has occurred twice, with results being non-detect for each well. Measured depth to water at this site has fluctuated between approximately 4.5 and 12.5 feet bsg. No water sample has been collected at this site below 20 feet bsg. The Tri-Valley Growers facility, located south of and down gradient from the subject property, has been undergoing investigation and remediation of an underground storage tank associated soils and groundwater contamination since 1987. In March 1998 three soil borings were advanced at the Tri-Valley site. The depths of these borings varied between 24 feet bsg and 34 feet bsg. Soil and grab groundwater samples were collected from each boring. Analytical results evidenced minor soil contamination to approximately 20 feet bsg, and significant groundwater contamination increasing with depth. The water sample HP-2W, from soil boring HP-2, evidenced 600 ppb TPHg and 11 ppb benzene at 24 feet bsg, and 17,000 ppb TPHg and 440 ppb benzene at 34 feet bsg. The water samples from the other two borings exhibited similar patterns of increasing contaminant concentration with depth. A copy of Draft Table Y prepared for the Tri-Valley Growers site is included for your information. PHSIEHD directed Tri- Valley to complete their vertical assessment. On April 30, 1999 a monitoring well screened from 30-40 feet bsg was installed and a report of the work will be submitted. In November 1998 PHSIEHD received a Request For No Further Action" closure report that had been prepared by ENSR on behalf of the subject site. In this document ENSR requests that the subject site be given a "Low Risk Ground Water Designation". Listed supporting data for the request of this designation was source removal, adequate site characterization, plume stabilization, mass balance calculations, and water supply well search. PHSIEHD agrees that the source of the contamination has been removed. According to the Tri-Regional Guidelines, Appendix B -- No Further Action Requests, designation of a site as a "low risk" site may occur after a complete site characterization has been made. Site characterization includes determining the full extent of hydrocarbon contamination, both vertically and laterally, in soil and groundwater.