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City of Stockton TL# 394-0027-01 <br /> March 10, 1994 Page 8 <br /> petroleum product volatilization, and field tested for organic <br /> vapors with a photoionization detector (PID) . The operation of the <br /> PID is explained below. <br /> Upon completion of the drilling and soil sampling, each borehole <br /> will be pressure grouted with a six-sack sand-cement slurry with <br /> approximately 5 percent bentonite to site grade. Soil cuttings <br /> from the borings will be sealed in United States Department of <br /> Transportation (DOT) approved 55-gallon steel drums . The drums <br /> will be labeled with information on the source of their contents <br /> and stored on site in a location remote from public access . The <br /> disposal of the drill cuttings is discussed below. <br /> A-2 Decontamination: Decontamination procedures will be <br /> implemented to reduce the potential for cross-contamination between <br /> soil borings . <br /> Before, during, and following drilling operations, the augers and <br /> associated drilling and sampling equipment will be thoroughly <br /> cleaned using a high pressure hot water (steam) washer. The hot <br /> water washer has a pressure of approximately 1,200 pounds per <br /> square inch and a water temperature of approximately 100 degrees <br /> Centigrade ( OC) . The sampler and brass sleeves will be washed in <br /> a Alconoxs detergent solution, rinsed with clean tap water, and <br /> air-dried prior to initial use and between each sampling event. <br /> The augers will be steam cleaned prior to the drilling of each soil <br /> boring. <br /> Prior to construction of monitoring wells, all casings will be <br /> cleaned in the same manner as the drilling equipment. <br /> A-3 Groundwater Monitoring Well Installation: Twining is a C-57 <br /> licensed water well drilling contractor (Contractor' s License No. <br /> 506159) . The groundwater monitoring wells will be installed under <br /> the direction of a California-registered geologist or -certified <br /> professional engineer. <br /> Soil borings for monitoring wells will be drilled and sampled <br /> according to Twining's "Standard Operating Procedures for Drilling <br /> and Soil Sampling" . Equipment used for drilling, sampling, and <br /> constructing wells, and well construction materials will be <br /> thoroughly cleaned according to Twining's "Standard Operating <br /> Procedures for Equipment Decontamination" . <br /> Groundwater monitoring wells will be constructed of minimum <br /> Schedule 40 polyvinyl chloride (PVC) , stainless steel, or other <br /> material casing. Screen may be machine-slotted or wire-wrapped. <br /> Casing and well screen specifications will depend upon project <br /> objectives, site conditions, and project budgets . The well screen <br /> and casing sections will be joined by factory-made flush-threaded <br />