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Workplan for 19256 North Highway 99- 12/22/98 page 7 Job No 024 98 ' 5.0 DRILLING PROCEDURES ' All soil borings and monitoring wells will be drilled using a drill ng operated by a drilling contractor who possesses a C-57 drilling license The logging of soil borings will be performed by an expenenced geologist,with oversight from a California Registered Geologist t (R G) or a Registerd Geologist The following procedures are used by Gallardo & ,Associates geologists to mrrnmze pollution of clean aquifers underlying contaminated zones 1 Drilling will cease if five feet of impermeable unsaturated material is encountered beneath an aquifer It will be assumed that any significant, unsaturated, impermeable ' layer, such as a clay layer, is an aqurtard separating shallow and deeper aquifers and should not be penetrated ' 2 Drilling will be terminated at a maximum depth of 10-15 feet below any perched or unconfined water table ' The driller and the Gallardo & Associates geologist will discuss significant changes in material penetrated by the drill ng, changes in drilling conditions, hydraulic pressure, and drilling action The Gallardo & Associates geologist will be present during the drilling of ' exploratory borings, will observe and record changes by time and depth, evaluate the relative moisture content of the samples, and note water-producing zones This record will be used ' later to prepare a detailed lithologic log Lithologic descriptions will include soil or rock type, color, grain size, texture, hardness, degree of induration, carbonate content, presence of fossils and other materials (gypsum, hydrocarbons) and other pertinent information ' 6.0 SGS. C1JTTM GS All soil cuttings generated by the drill ng will be placed in 55-gallon DOT approved drums or placed on and covered with six-nut Visquene, and stored onsite pending laboratory analytical results ' 7.0 SOIL SAM PLMG IN BG1RIEH®LIES ' U S Environmental Protection Agency standards serve as the foundation for all field sampling operations performed by GWIardo& Associates EPA SW 846 is the primary publication from which procedures are derived While some aspects of field and laboratory work may ' be delegated to the California Department of Health Services, the California Water Resources Control Board, CVSSRWQCB and the SJCEHD establish the general and specific criteria for sampling performed in connection with underground storage tanks (USTs) ' 7.1 Sample Intervals ' Soil samples will be taken a five-foot intervals, changes in lithology, at the capillary fringe, or where obvious contamination is observed Selected soil samples will be placed in an ice tchest filled with ice and taken to a State-certified analytical laboratory for analysis