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Installation of Monitorina Wells <br /> To further assess the extent of impacted soil and groundwater at the site, and to establish the <br /> groundwater gradient, a total of three soil borings will be advanced at the site (Figure 2). <br /> The borings will be advanced to depths of approximately 50 feet below ground surface (bgs). <br /> Soil samples will be collected at five-foot intervals or significant changes in lithology. Drilling will <br /> be conducted by a State licensed (C57) drilling company. A field geologist will be present to log <br /> all drill cuttings and soil samples. Each soil sample will be field screened with a Photoionization <br /> Detection (PID) meter or similar instrument and an estimated two samples from each of the three <br /> borings, based on field observations (i.e. odor, discoloration, PID readings), will be placed in a <br /> cooler with ice and submitted for laboratory analysis. <br /> Groundwater Monitoring Wells Construction Details <br /> All borings will be completed as groundwater monitoring wells. The monitoring wells will be <br /> constructed of 2-inch inside diameter schedule 40 PVC well screen and casing. The groundwater <br /> table had been initially observed at 45 feet bgs and stabilized at 36 feet bgs. A 20-foot well screen <br /> will be installed with five feet of screen above the water table. A0.010-inch well screen slot and. <br /> #2112 mesh sand pack will be used. Neat cement will be used to seal the wells in accordance with <br /> • California Well Standards (December 1981). To protect the integrity of the wells, locking, water- <br /> tight well plugs will be installed on each well and a water-tight wellhead labeled "monitoring well" <br /> will be concreted over each well. Proposed well construction details are shown on Figure 3. The <br /> top of casing of the new and existing wellheads will be surveyed to assess groundwater gradient <br /> and flow direction. All drill cuttings will be stored on site in 55-gallon drums pending laboratory <br /> results. <br /> Sample Analysis <br /> The soil samples from the soil borings will be immediately placed in a cooler with ice and <br /> delivered under chain-of-custody documentation to a State-certified analytical laboratory. Soil <br /> samples will be analyzed for total petroleum hydrocarbons as gasoline (TPHg), benzene, toluene, <br /> ethylbenzene, and xylenes (BTEX) by EPA Methods 8015m/8020, and oxygenate fuel additives <br /> by EPA method 8260. <br /> Well Development and Groundwater SamQlin� <br /> Measurement of depth to water in all wells will be completed to evaluate the direction and <br /> magnitude of the groundwater gradient beneath the site. The new wells will be developed using <br /> surge and bail techniques until the produced water is relatively sediment free. Prior to the <br /> collection of groundwater samples, a minimum of three well volumes (casing and sand pack) will <br /> . be purged. Temperature, pH, water elevation, and electric conductivity will be measured and <br /> w:192054.00014gvrls\Workplan2.doc 2 <br /> r <br />