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Geologccat Tech&CS lax Page 5 Valentine(Castle Motors) ' Report—Additional Site Characterization Project No 723 2 . January 21,2004 are on four sides of the cap and approximately 1/ inch in diameter This section is also covered by stainless steel screen Once the CMTTM tubing for wells MW-7, MW-8 and MW-9 had been installed, alternating sections of#12 Monterey washed sand and weighted bentonite pellets were used to fill the annulus of the borehole Plastic casing centralizers supplied by the manufacturer were not used because they exceeded the inside diameter of the auger The auger flights were removed one by one during the process to ensure correct annulus material placement and to keep the tubing centered in the borehole A granular bentonite transition seal was installed above the top sand filter pack and hydrated with clean water prior to installing the surface seal in each borehole. A surface seal was installed by pumping a neat cement grout (augmented with < 4% bentonite) into the borehole through the augers The wells were secured with locking watertight caps encased in flush mounted traffic rated well boxes The wells' construction details are included in Table 2, Appendix A and are illustrated on the boring logs included in Appendix C ' 30 SOIL SAMPLE ANALYSES Three soil samples obtained from each boring were submitted to Sherwood Laboratories in Hilmar, California (Department of Health Services Certification # 1400) for the following analyses • Benzene, toluene, ethylbenzene and xylene (BTEX) by EPA method 8020 Methyl tertiary butyl ether (MTBE) by EPA method 602 • Gasoline range petroleum hydrocarbons (TPH-G) by EPA method 5030/8015(m) A summary of the soil laboratory data is attached in Table 1, Appendix A, and the lab data reports are attached in Appendix B 1 GTI attempted to submit the laboratory data electronically to GeoTracker as required under AB2886 in December 2003 and again on January 5, 2004 but was unsuccessful There is a problem with the State computer system and the data transfer will be attempted again in the ' future 4.0 DISCUSSION The following data were gleaned during the installation of the three CMTTM wells ' 41 Geology and Hydrogeology of the Site In the location of borehole MW-7 the subsurface was characterized as follows Li The subsurface contained alternating layers of sands, silts and clays ❑ Sand intervals occur at 0 — 20, 36— 50, 63 —78 and 87 —91 feet bgs o The sands ranged from very fine to very coarse grain size and brown, grey, and olive-grey in color CaCO3 inclusions, iron oxide staining and brown/black organic