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8.0 RECOMMENDATIONS FOR REMEDIAL INVESTIGATION The following section describes in general terms some of the initial tasks recommended for the Remedial Investigation. This work may need to be carried out in a"phased" approach. Upon completion of a remedial investigation, a feasibility study should identify the most appropriate remedial option for this site. The remedial investigation feasibility study and final remedial action plan are not included in this worknlan. A Remedial Investigation should be developed to address the following site conditions determined from previous investigation: 1)Smog America, an automobile repair facility is located on the northwest corner of the site. Quick-N-Save, a gasoline station and market at 2057 S. El Dorado Street is located approximately 120 feet northwest of the site, on the west side of S. El Dorado Street. Quick- N Save is currently under investigation with SJCEHD oversight due to a reported leaking UST(s) and subsequent gasoline impact to groundwater. The position of our previous groundwater sample locations GW-1 through GW-5 were down gradient of Smog America and Quick-N-Save The VOC and GRO analytical results for samples collected at GW-2 and GW-4 indicate that the documented gasoline release to groundwater at Quick-N-Save has possibly impacted the groundwater beneath the site in the northwest portion of the site. It is also possible but less likely, based on site conditions known at this time, that the gasoline detected in groundwater at GW-2 and/or GW-4 resulted from a release at Smog America or a release on the subject site itself. ROKEN recommends collecting several (3 to 4) additional soil and groundwater samples in the west-central and northwest portion of the site. Soil and groundwater samples should be analayzed for the following laboratory analyses: EPA Method 8260b-VOCs, TPH as Gasoline, 7 fuel additives and lead scavengers EPA Method 8270 - Semi Volatile Organic Compounds EPA Method 8015M -TPH as Diesel and Motor Oil EPA Method 6010 - LUFT 5 Metals (Cadmium, Chromium,Nickel, Lead, Zinc) 2) The analytical results for groundwater samples collected from sample locations GW-6 through GW--10 indicate that there is significant gasoline impact to groundwater in southern portion of the site which is most likely attributed to gasoline releases from one or more of the on-site USTs in this area. Low levels of DRO were detected in groundwater at these sample locations but the levels did not exceed the ESL. Lead concentrations detected in groundwater exceeded the ESL at three (3)sample locations (GW-7, GW-9 and GW-10). Numerous VOCs which are known gasoline constituents (including Benzene) were detected at high concentrations in groundwater. Initial response to this condition is the primary subject of this workplan. However the magnitude and extent of this UST release has not been determined and will not be determined by the UST removal and over-excavation tasks presented in this workplan. ROKEN recommends collecting several (3 to 4) additional soil and groundwater samples in the southern and southeastern portion of the site. Since gasoline released from the on-site USTs appears to have moved off site to the south 14