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• ' Richmond, California A complete description of typical direct-push drill ngs and soil sampling methods can be found on the following web page http//www precistonsampling com 312 Soil samples collected from the central soil boring will be analyzed by a state-certified on-site mobile laboratory The results provided by the mobile laboratory will enable Blaes to determine the vertical extent of hydrocarbons in soil without over-drilling the boring Soil samples collected from the proposed lateral extent soil borings will be analyzed at a state-certified fixed laboratory ' Soil samples will be analyzed for the following constituents total petroleum hydrocarbons as gasoline (TPHg) using EPA Method 8015, benzene, toluene, ethyl benzene, and total xylenes (BTEX) using EPA ' Method 8021 Up to two soil samples, one at the lowest sample depth and one with the highest TPHg concentration, from each boring will also be analyzed for oxygenated compounds Oxygenate compounds will include the following analytes and analysis tert-butyl-alcohol (TBA), methyl-tert-butyl-ether (MTBE), di-isopropyl-ether (DIPS), ethyl-tert-butyl-ether (ETBE) and tert-amyl-methyl-ether (TAME) using EPA method 8260 The certified analytical report provided by the laboratory will be provided with the final ' report 3 2 SITE CHAgACTEgIZATI ' Due to the current groundwater elevation, which has submerged the screen interval of eight existing monitor wells at the site, Blaes proposes the installation of new monitor wells within 5 feet of the existing wells (Figure 2) The new nested (two casings per bore hole) wells would incorporate screen intervals that will accommodate the large swings in groundwater level occumng at the site One additional nested groundwater well will be installed on the southern corner of the site to further evaluate the extent of hydrocarbons in that direction 3 2 1 Grgundwater Monitor Well Installation Blaes will contract a licensed drilling contractor, Gregg Drilling of Martinez, California, to install up to ' eight groundwater monitor wells As mentioned above, seven of the proposed monitor wells will accompany the existing on-site monitor wells and one additional well is planned for installation at the southern portion of the site (Figure 2) The new wells to accompany the existing wells will be constructed ' with two, 2-inch nested well casings The existing and proposed well casing screen intervals are presented on Table 3 One additional well (MW-8a) will be constructed with a single 2-inch casing, screened between approximately 37 to 62 feet bgs This should account for recent fluctuations in groundwater levels ranging from 66 feet bgs in February 1995 to 37 feet bgs in March 1999 Well installation activities will comply 1 7