SITE INFORMATION AND CORRESPONDENCE

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L.� Now 1419 Charter Way Former Stefano's Gas Station Page 2 The groundwater flow direction has been predominately to the east. Currently no repeatable sampling points have been installed off site to the east. EHD agrees with the Ramage's conclusion that additional investigation to define the lateral and vertical extent of the contamination is required. The presence of contamination in the potentially faster-moving groundwater in the sand zones at 60 feet and 105 feet bsg makes it necessary to install additional sampling points to monitor migration of the contamination plume. EHD recommends installing at least one additional well with a screen section targeted at the sand zone at 105 feet bsg on site. EHD also recommends installing at least 3 additional wells with screen sections targeted for the sand zone at 60 feet bsg in the down-gradient direction,with one well near MW-4 and one on the sidewalk or parking lot of Sheba Liquors. Submit a work plan to EHD to defuse the lateral and vertical extent of the groundwater contamination plume by March 5, 2003. On November 25, 2002, EHD was informed by the sampler at the site that a minute amount of free product was again found in MW-2, and groundwater samples were not collected from the well for that reason. The sampler also noted that no free product could be observed after the purging the well. EHD directed the sampler to return to the site and collect groundwater samples from MW-2 for lab analyses. EHD requests groundwater samples be collected from all wells during future quarterly monitoring events if no significant amount of free product is presence and free product is not observed after the standard 3 saturated casing-volume purge. In a telephone conversation on December 5, 2002, Ramage proposed initiating a groundwater extraction test in order to assess the feasibility of adopting the technology for interim remediation to begin removal of the mass of dissolved hydrocarbons in groundwater. The concentrations of 1,2-DCA found in the MW-2 and MW-3 samples continued to exceed by several orders of magnitude the California Department of Health's Primary Maximum Contaminant Level (MCL) for drinking water of 0.5 µg/1. TBA has a higher solubility than MTBE,with relative low sorption to soil (and therefore moves fairly rapidly in groundwater). Ramage also pointed out that due to the relatively tight silt and clay in both the vadose zone as well as below the groundwater table, technologies such as soil vapor extraction and air sparging may not be suitable for this site. If you and your consultant wish to pursue the strategy of interim remediation using groundwater extraction and conduct a feasibility test, EHD recommends you to submit a proposal for the test. The proposal should provide justification and all appropriate data to demonstrate the need of an interim remediation and implementation of a feasibility test. Present in the proposal, at minimum: