COMPLIANCE INFO_1991-1997 - Laserfiche WebLink

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A-2 Upon completion of the drilling and soil sampling, each borehole will be pressure grouted with a six -sack sand -cement slurry with approximately 5 percent bentonite to site grade. Soil cuttings from the borings will be sealed in United States Department of Transportation (DOT) approved 55 -gallon steel drums. The drums will be labeled with information on the source of their contents and stored on site in a location remote from public access. The disposal of the drill cuttings is discussed below. A-2 Decontamination: Decontamination procedures will be implemented to reduce the potential for cross -contamination between soil borings. Before, during, and following drilling operations, the augers and associated drilling and sampling equipment will be thoroughly cleaned using a high pressure hot water (steam) washer. The hot water washer has a pressure of approximately 1,200 pounds per square inch and a water temperature of approximately 100 degrees Centigrade (°C). The sampler and brass sleeves will be washed in a Alconox® detergent solution, rinsed with clean tap water, and air-dried prior to initial use and between each sampling event. The augers will be steam cleaned prior to the drilling of each soil boring. Prior to construction of monitoring wells, all casings will be cleaned in the same manner as the drilling equipment. A-3 Groundwater Monitoring Well Installation: Twining is a C-57 licensed water well drilling contractor (Contractor's License No. 506159). The groundwater monitoring wells will be installed under the direction of a California -registered geologist or - certified professional engineer. Soil borings for monitoring wells will be drilled and sampled according to Twining's "Standard Operating Procedures for Drilling and Soil Sampling". Equipment used for drilling, sampling, and constructing wells, and well construction materials will be thoroughly cleaned according to Twining's "Standard Operating Procedures for Equipment Decontamination". Groundwater monitoring wells will be constructed of minimum Schedule 40 polyvinyl chloride (PVC), stainless steel, or other material casing. Screen may be machine -slotted or wire -wrapped. Casing and well screen specifications will depend upon project objectives, site conditions, and project budgets. The well screen and casing sections will be joined by factory -made flush -threaded connections. The well filter pack material will consist of appropriately -sized pre -washed sand. The filter material will be placed in the annulus between the boring wall, from the bottom of the boring to approximately 2 feet above the top of the screen. Subsequent to filter pack emplacement, preliminary development may be performed to provide a uniform filter pack about the casing. Above the filter pack, a 2- to 4 -foot thick bentonite seal will be installed.