FIELD DOCUMENTS - Laserfiche WebLink

Home Browse Search

Ms. Devra Lewis • • Project 812717 April 9,2001 Page 2 of 4 Following approval of the workplan by the RWQCB, IT will schedule a licensed well driller and arrange for all materials and equipment needed to complete the proposed scope of work. IT will contact TASK 2- FIELD ACTIVITIES Task 2A - Exploratory Boring and Soil Sampling IT will supervise installation of groundwater monitoring wells at the seventeen proposed locations (see Figure 2) to provide long-term groundwater monitoring locations for assessment of potential plume migration. Borings will be drilled by a licensed California drilling contractor using air rotary casing hammer drilling methods. Proposed monitoring wells will be located adjacent to CPTs. If the well is proximal (within 50 feet) of the CPT profile location, additional logging will not be conducted. The proposed well designs are based upon the hydrogeologic and analytical data from the recently complete CPT and HydroPunch groundwater investigation. Exploratory borings will be drilled using air-rotary casing hammer drilling equipment to minimize potential for cross-contaminating deeper water bearing zones and to reduce the effects of flowing sand conditions encountered during previous drilling at this site. The casing hammer method utilizes a heavy wall metal casing, driven as the drill bit advances, to seal off the boring from the surrounding formation. Continuous samples are collected from cuttings and drilling fluids are not used. The soil samples will be field screened for the presence of volatile organic compounds using a photoicnization detector (PID). An IT geologist will prepare detailed boring logs based on samples and drilling return materials. Samples will be logged according to the Unified Soils Classification System. All work will be supervised by a Registered California Geologist and will conform to regulatory standards. All drill cuttings and excess soil samples will be stored temporarily in a soil bin. A composite sample will be collected from the soil cu ings and will be analyzed to determine an appropriate disposal method. Drilling equipment will be decontaminated by steam cleaning after each boring to reduce potential cross-contamination. All deco tamination water will be containerized and a sample will be analyzed to determine the appropriate disposal method. Task 2B - Groundwater Monitoring Well Installation The exploratory borings will be converted to 2-inch-diameter groundwater monitoring wells. Screen intervals of 10-feet in length will be used for deeper interval monitoring wells (B through D- Zone). Fifteen feet of casing will be installed in A-Zone wells to allow for seasonal water table fluctuations. A filter pack of Lonestar No. 3 (or equivalent) sand will be placed in the annular IT CORPORATION CA My DocumentsTrojectsTort of StocktonMell Install\workplan.doc Rev.0,4/9/01