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Mr. Clapper and Mr. Romig <br /> September 24, 1996 <br /> Page 8 <br /> shown over the top of the pipe bedding material to prevent soil particles from clogging the <br /> gravel. A combination of perforated and solid-wall drain pipe will be required to <br /> hydraulically connect the gravel bedding at each end of the Dam No. 4 embankment <br /> crossing from station 13+90 to 17+20. A bedding drain located near the seepwater pond <br /> at station 1 +00 will dewater the gravel bedding material discharging into the area tributary <br /> to the seepwater collection system(ref.dwg.D4-2-04). The water that is collected by this <br /> bedding drain should be tested periodically to detect pipeline leakage. As an additional <br /> measure of protection to the Chalk Mountain'Intercepter, the pipeline will be installed along <br /> the Dam 4 side of the roadway so that leakage from the pipeline would tend to flow into <br /> Dam 4 instead of the intercepter. <br /> As shown on Drawing 134-2-01, we propose that the lower end of the existing 4- <br /> inch diameter discharge pipeline be rerouted to daylight within the seepwater pond basin. <br /> The pipeline could then be used along with one of the existing 15 HP Flygt pumps as an <br /> emergency backup system, and also as a temporary pump during construction, with the <br /> Flygt pump being placed directly in the seepwater pond. The existing diesel generator <br /> could remain at the pump station to power the 15 HP pump. <br /> Proposed Puma Station Modiflemlons <br /> The pumps that are currently installed in the Seepwater Pump Station are not <br /> capable of delivering water to Robinson Reservoir due to the higher pumping head involved. <br /> We propose that the three existing pumps be replaced with two 75 horsepower vertical <br /> in-line type pumps (ref. dwg. D4-6-01). The in-line pumps would be hard-piped into one <br /> of the 8-inch pipes that connect the pump station to the seepwater pond. The wet well <br /> of the pump station could then be drained and function as a dry well. This would allow <br /> for use of a wider range of water levels In the pond since the level would no longer be <br /> limited to the elevation of the top of the existing wet well, which is well below the level <br /> ZO' d Z00' ON bb: TT 96 bZ daS Z08Z-T9Z-202-T : 131 3oSSd '8 jaiaagM • M• M <br />