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ameO Before setting the bentonite transition seal each filter pack will be pre- developed by surging the water within the casing to prevent future settling. AMEC anticipates using bentonite for the transition seal, grout for the sanitary seal above the transition seal, and a traffic-rated well vault. The wells will be constructed in accordance with the appropriate state and local agency requirements. Final well materials, screening, and construction details will be determined in the field based on lithologic, hydrogeologic, and other Site-specific conditions. I 3.4.3 Soil Screening and Sampling During installation of each well,.soil samples will be collected to document lithologic conditions ffor screen interval selection and for the collection of select soil samples. At least one soil L� boring will be continuously cored to calibrate the CPT logs to observed lithologic conditions. During drilling, the Field Geologist under the supervision of a California Professional Geologist, Lwill document field classification of soils, progress of drilling, final completion depth, photo- ionization detector (PID) readings, sample and core intervals, soil recovery on the boring logs, and the nature and resolution of any problems encountered. Samples will be described using ASTM Standard D2488-00 visual-manual method, which 'is based on the Unified Soil Classification System (USCS). LSoil samples will be field screened (approximately every 5 feet)for petroleum hydrocarbons and VOCs using a PID and visually inspected for soil staining. The PID will be fitted with a L10.6 electron volt (eV) lamp and will be calibrated daily to a 100 parts per million by volume (ppmv) isobutylene standard. The PID will be used to measure soil headspace concentrations L by placing soil samples in plastic resealable bags from select,lithologic intervals and measuring accumulated headspaces. i - Up to two soil samples per boring will be collected for Site characterization purposes. Samples will be collected from depths suspected to have elevated petroleum hydrocarbon concentrations based on field observations, PID readings, and MIP data. Soil samples will be analyzed for the following constituents as shown in Table 1. I ' • TPHg by U.S. EPA Method 8015M; • TPHd by U.S. EPA Method 8015M; and • BTEX, fuel oxygenates compounds (Di-isopropyl ether, Ethyl tert-butyl ether, Tert- amyl methyl ether, Tert-Butanol, Methyl tert-butyl ether), and lead scavengers (1,2-Dibromoethane and 1,2-Dichloroethane) by U.S. EPA Method 82608. +�+ Soil samples to be analyzed for TPHg, BTEX, fuel oxygenates, and lead scavengers will be field preserved according to U.S. EPA Method 5035 protocol. LAMEC Geomatrix, Inc. P:\Project\140005\14443_Caltrans\TO 10\11000_PLANS\AS WP—March 2010\AS WP.doc 9