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• <br /> COMMENTS TO WORK PLAN FOR ADDITIONAL <br /> SOIL AND GROUND-WATER INVESTIGATION <br /> GREAT WESTERN CHEMICAL COMPANY <br /> General Comments: <br /> To adhere to State of California Business and Vocations Code, the <br /> Work Plan must be signed and sealed with license number by a <br /> State of California Registered Geologist, Certified Engineering <br /> Geologist, or Professional Engineer. <br /> Soil Samplina: <br /> 1. Before collecting samples for chemical analysis, the <br /> Department recommends a minimum of two continuously cored <br /> vertical borings be completed to provide for detailed and <br /> accurate characterization of sediments at the site. In <br /> addition to the predetermined sample intervals, samples <br /> should be collected from the bottom of fine grained geologic <br /> intervals identified by the continuous cores. The cores <br /> should be located in areas with known contamination and in <br /> close proximity to proposed sample borings. <br /> 2 . The Department recommends screening of the continuous cores <br /> with a direct reading instrument to provide preliminary <br /> information on potentially contaminated depths. The Work <br /> Plan should indicate that coring will continue beyond ten <br /> feet if field instrument readings indicate contamination <br /> exists at ten feet. The Work Plan should also include a <br /> contingency for increasing the depth of sampling beyond ten <br /> feet based on readings from screening instruments. <br /> 3 . In addition to the boring locations identified in the Work <br /> Plan, borings should also be located at or near the points <br /> where soil contamination was identified during the July 1992 <br /> investigation (ED-2, ED-3 , & ED-4) . Soil borings should be <br /> relocated as discussed during our November 20, 1992, <br /> telephone conversation. <br /> 4 . The Work Plan must include a description of the method to be <br /> used to decontaminate drilling and sampling equipment <br /> between borings and each sample collection. <br /> 5. The Department recommends sealing all boreholes by cementing <br /> bottom to top using a cement-bentonite grout comprised of 2 <br /> to 3 percent non-beneficiated bentonite prehydrated at 7 to <br /> 8. 5 gallons of water per sack of cement. <br /> Waste Management: <br /> Soil cuttings from borehole drilling should be stored onsite in <br /> 55-gallon drums until a disposal option is selected. <br />