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W GealogccalTeclwcslnr Page 4 Valentine(Castle Motors) ' Report—Additional Site Characterization Project No 723 2 . January 21,2004 boreholes soil samples were collected for geological and analytical evaluation at five-foot intervals Field observations were made noting sediment type, grain size and clay content, ' moisture content, obvious odor, visible evidence of contamination, i e , color change due to reduction of iron or discoloration from hydrocarbons and other pollutants, and any readings above background levels on an organic vapor meter (OVM) The OVM is a field portable photo ionization detector that uses a 10 0 eV lamp to detect compounds with ionization potential below 10 0 eV (hydrocarbon range) Boring MW-7 was not monitored with the OVM due to an equipment malfunction Boring logs providing sediment description using the USCS and field observations were maintained by a GTI staff geologist, working under ' the supervision of Ray Kablanow, a California Registered Geologist and Certified Hydrogeologist The boring logs are attached in Appendix C Soil samples were collected in 6 0-inch brass liners using a 2 0-Inch modified California split spoon sampler All soil samples were sealed with Teflon sheets, capped, labeled and placed in a cooler at 4° Celsius for transport to the laboratory following Chain of Custody protocol ' 2.3 Continuous Multi-chambered Tubing (CMTTM) Well Installation ' The objective of installing CMTTM wells was to monitor multiple lithologic units to define the lateral extent of the groundwater plume Originally, GTI has intended to monitor only three units per well location, but the bottom cap units ordered from Solinst Canada contained an integral screened unit for monitoring the central chamber in the multi- chambered tubing This allowed GTI to install four(4) screened intervals per borehole All three multi-chambered wells were constructed with manufacturer (Solinst Canada) ' supplied materials The deeper screened intervals of the wells are designated with 100, 200, and 300 series labels to differentiate the intervals monitored The table below illustrates the well construction details (see boring logs in Appendix C for complete construction details) Well o. TD Screen Sand Pack (ft) Interval (ft) (ft) - 74 - 79 MW-307 89 86 - 91 MW-8 955 41 32 - 42 MW-108 52 - 53 MW-208 76 72 - 77 - i 9 955 45 .36 - 46 MW-209 so 76 - 81 The screened intervals were chosen based on the lithology encountered in each borehole The CMTTM tubing was laid out on the ground and the screened intervals constructed using hand tools The actual perforation in the wall of the CMTTM tubes is approximately four inches in length and is covered by stainless steel mesh The perforations in the bottom caps