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Work Plan for Extended Site Ccterization: 7500 West Eleventh Street, Tracy, CA.*RMO Page 11 �.. 6.5 Field Modification; Drilling Locations, Sampling Intervals, Well Construction It is planned that the borings and wells will be located at the approximate locations previously described and that soil samples will be recovered from them at the approximate 5-ft. specified depth intervals. However, when appropriate, the California-licensed geotechnical engineer in responsible charge of the project will use visual and olfactory �• indicators of the presence or absence of hydrocarbons in soil cores and the details of the stratigraphy revealed in the borings to select the final locations for the push probe and well borings, the depths at which soil samples will be recovered, the total depth of the borings and +- the screened intervals and other construction details of the wells. In making these field decisions, the engineer will apply the principals of the observational method (Peck 1969), a founding principal of geotechnical engineering practice that was belatedly recognized by the United States Environmental Protection Agency (USEPA) as an essential element of cost- effective environmental site characterization programs (United States Environmental Protection Agency 1997), but is, unfortunately, still unrecognized by many local environmental regulatory agencies. 6.6 Disposal of Drill Cuttings Drill cuttings from the well borings will be retained in 50-gal, steel drums. When full, the drums be will closed and placed in storage on the 7500 West Eleventh Street property until the results of analyses of soil and water samples are available. When the analytical results are obtained, the soil in the drums will be classified and, if clean, disposed as clean fill on the 5700 East Eleventh Street property. Soil affected by components of fuel hydrocarbons will be '- loaded into a truck and shipped for disposal at the Forward Landfill, a Class II disposal facility in Manteca, California. 6.7 Well Development Following construction, the wells will be developed by pumping and surging and by bailing a minimum of 10 well volumes from each. The development water will be staged on-site in 50-gal. closed-top steel drums. When data is available on the concentrations of analytes of concern in samples recovered from the newly installed groundwater-quality monitoring wells, drums that contain clean water will be emptied by decanting them onto the site. Drums containing water affected by hydrocarbons will be emptied into a vacuum truck and their contents shipped off-site for disposal at a permitted recycling facility. 6.8 Survey of Well-head Locations and Elevations The locations of the new wells will be surveyed and the elevations of both the top of the casing and the wellhead box cover frame of each will be determined relative to mean sea level (MSL). sic