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GENESIS ENGINEERING&REDEVELOPMENT <br /> maximize pumping from the central part of the Site where nitrate concentrations are currently <br /> highest. <br /> A secondary factor in design and operation of the groundwater extraction system is the <br /> capacity of the NPWS system. The demands on the NPWS from end users can be variable, <br /> and during periods of low use pressure in the system may rise. The groundwater extraction <br /> system will be designed to temporarily shut down when back pressure in the NPWS system <br /> exceeds 60 pounds per square inch("psi'). <br /> 2.2 Groundwater Extraction System Design <br /> The main components of the groundwater extraction system include(Figure 7): <br /> 1. Four extraction wells; <br /> 2. Piping, valves, gauges, meters, and sampling ports between the extraction wells and <br /> blending tank; <br /> 3. A 5,000 gallon blending tank; and <br /> 4. Piping, valves, gauges,meters, and sampling ports between the blending tank and <br /> the NPWS. <br /> 2.2.1 Extraction Wells <br /> As indicated in the previous section, one existing well (AT-1 S) and three proposed wells will <br /> be used to extract groundwater from beneath the Site. Extraction Well AT-IS is a 6 inch <br /> diameter well that is screened(0.02 inch slot size)between 33 feet and 53 feet bgs with the <br /> sand pack around the screen consisting of#3 Monterey sand. The geologic log and well <br /> construction details for AT-1 S are included on Table 1 and in Appendix A. <br /> The proposed extraction wells will also be 6 inches in diameter, will be screened between 35 <br /> and 60 feet bgs, with a screen slot size of 0.01 and a sand pack that consists of#45 Monterey <br /> sand. The screen slot size and sand pack materials for the proposed wells were chosen by <br /> consulting reference texts for sizing recommendations based on the geologic materials <br /> through which shallow groundwater flows. <br /> Each extraction well will be equipped with a submersible pump, a 2 inch diameter discharge <br /> pipe, a separate tube for depth to water measurements, and an electrical control box (Figure <br /> 8). <br /> R.F.Land Inc. 5 of 11 <br /> Groundwater Extraction Work Plan <br /> October 2014 <br />