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' GeoogkAtTedut&slnc Page 3 <br /> Site Conceptual Model Report <br /> Project No 724 2 <br /> May 2,2005 <br /> ' 2.0 ASSESSMENT OF IMPACT <br /> 2.1 Release Documentation <br /> The SJC PHS/EHD documented the presence of contamination at the site in their March 4, <br /> 1992 correspondence (copy included in Appendix A) They noted the removal of the tanks <br /> ' on December 27, 1991 and stated that the levels of contamination present preclude <br /> consideration for site closure In their letter, they also state that an "Underground Storage <br /> Tank Unauthorized Release (Leak)/Contamination Site Report" has been filed This action <br /> ' constituents an official government acknowledgement of an underground storage tank leak <br /> GTI has not reviewed the UST files at SJC PHS/EHD for evidence of failed tank or line tests <br /> ' etc occurring prior to the USTs' removal in 1991 This level of scrutiny is not warranted at <br /> this time given the county supervised over-excavation of impacted soils in 1993 <br /> ' 2.2 Site Investigation <br /> As outlined above in Section 10, the site investigation has consisted of several soil borings, <br /> ' the installation of monitoring wells, Cone Penetrometer Testing (CPT), off site contamination <br /> research and receptor well surveys These efforts generated a significant amount of data that <br /> will be summarized in the following sections <br /> M2.2.1 Soil <br /> Soil samples were collected from both the vadose and saturated zones The data were used to <br /> ' estimate the lateral and vertical extent of the contamination in the two media Specific <br /> analyses that have been utilized in the investigation include <br /> ' General Soil Samples <br /> • Diesel range petroleum hydrocarbons (TPH-D) by EPA method 3540/8015(m) or <br /> 8020 <br /> ' • Gasoline range petroleum hydrocarbons (TPH-G) by EPA method 5030/8015(m) or <br /> 8020 <br /> Benzene, Toluene, Ethylbenzene and Xylene (BTEX) by EPA method 8020 <br /> ' • Gasoline oxygenates MTBE, DIPE,ETBE, TAME and TBA by EPA method 8260 <br /> ' Waste Oil Tank Samples <br /> • Total Lead by method 7420 or SW6010 <br /> • EDB by EPA method 504 <br /> ' Halogenated hydrocarbons by EPA method 8080 <br /> • Oil and Grease petroleum hydrocarbons by method 418 1 <br /> • PCBs by EPA method 8080 <br /> ' e CAM-17 Metals <br />