ARCHIVED REPORTS XR0011754 - Laserfiche WebLink

Home Browse Search

i.. Extended Plume Definition:-7500 W IIth St.,Tracy,CA. Page 10 I.Mr was drilled to an approximate depth of 25 ft. BGS. The PVC well casings featured 4.02 in., machine-cut slots from between approximately 5 ft. BGS to the total depth of the well. A 2 ft. thick bentonite seal with its bottom approximately 1 ft. above the screened interval of the casing was placed to fill the annular space between the casing and the boring wall. Number 2 Monterey sand filter material was placed between the screened casing and the wall of each boring. The well heads, which are fitted with lockable casing caps, were enclosed in flush- mounted, steel well vaults with steel covers rated for heavy vehicular traffic conditions. SJC's California-licensed geologist logged all of the borings. These and other details of the well construction can be found in the well logs compiled in Appendix A. (For convenience of reference, Appendix A contains copies of the logs of all wells and borings that have been drilled by SJC on the Navarra Site.) While the borings were being drilled, the drilling equipment was used to recover soil samples in 2 in. diameter by 6 in. Iong copper tubes. Discrete samples were recovered from the subsurface at 5 ft. intervals. Each sample tube was then cleaned externally, its ends covered with Teflon foil and closed with tightly-fitted plastic caps secured with adhesive-less tape. Each tube was then labeled for identification, entered into chain-of-custody control and packed on chemical ice for transport to Severn Trent Laboratories, Inc.'s (STL) Pleasanton, California laboratory within 14 hours. tr 4.5 Analyses of Soil Samples Each soil sample submitted to the laboratory was analyzed for the following suite of analytes. Analyte Method of Analysis Total Petroleum Hydrocarbons EPA Method 8015M (quantified as Diesel) Total Petroleum Hydrocarbons EPA Method 8260B (quantified as Gasoline) �. Benzene EPA Method 8260B Toluene EPA Method 8260B Ethyl benzene EPA Method 8260B •- Total Xylene Isomers EPA Method 8260B STL's laboratory is certified by the DHS to perform the soil analyses listed above. The results of the analyses of the soil samples are compiled in Table 2. Copies of the Certificates of Analysis are compiled in Appendix C. sic