SITE INFORMATION AND CORRESPONDENCE_FILE 2

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Mr. Ken Gillies Gillies Trucking 3931 Newton Road, Stockton Page 2 of indicate an interval of intensely impacted groundwater in or just above the First Riverbank sand. UEC infers that impacted groundwater in the Second Riverbank channel sand, generally lying between 75 and 90 bsg, locally as deep as 100 feet bsg, is limited to the former tank pit area. Sample points toward the south and west support this interpretation in those directions, but there is not sufficient data toward the north, in the direction of the domestic well, to support this conclusion. Data from monitoring well GT-5 has shown both the presence and absence of hydrocarbon impact in the past in the second riverbank sand toward the north, but this has not been integrated into or explained in the context of the current model. UEC did not estimate the extent of impacted groundwater in the possible third Riverbank sand unit, lying approximately 110 to 120 feet bsg, as only two analytical data points were obtained in this poorly characterized sand unit. The EHD is concerned because the diesel and gasoline concentrations in the CPT-1 sample from this interval were higher than the sample from the Second Riverbank sand interval in CPT-1 and there was no explanation for this. Indeed, UEC noted that the reason for this anomaly is uncertain at this time. You have requested site closure and/or reduction of monitoring requirements for your site in the past. The EHD has not granted site closure or reduced monitoring requirements due to several concerns with the release on your site, among which are: • The unknown effects of the Gillies domestic well (G-1) on impacted groundwater and vice versa; • The lack of adequate characterization of the plume of impacted groundwater that is needed to ensure proper management of the plume to protect more than 30 water supply wells identified by your consultant within a 2,000-foot radius of your; and • The lack of an adequate demonstration that the plume of impacted groundwater is stable and/or contracting, and that the Basin Plan water quality objectives will be achieved within a reasonable time frame. At the meeting in our office attended by you and County Supervisor Dario Marenco on 13 November 2003 and in our letter of 26 November 2003, the EHD provided you with the concerns that needed to be addressed for your site and the criteria for site closure consideration. The items included: • Construction details for the Gillies domestic well (G-1) and the Barbot domestic well;