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;.v::G iER: =.FFEC~S Oi ::II:~:~:, 0:: ~:~TERS <br />Effects on Surface katers <br />antit -All points of diversion for water rights in :~ewlin <br />Creek lie upstream prom the lease.azea and generally withdraw all <br />water from the strea.:. prior to its reaching the leases. The only <br />surface disturbances caused by mining, the portal facilities and <br />spoils areas, lie in the first southern sub-basin of Newlin Creek <br />outside of its main drainage. In this sub-basin some modification <br />of the drainages will be undertaken. Collection ditches will be <br />constructed dos~a gradient from the spoils area and portal facilities <br />to catch sediment from runnoff and channel. it into the two stage <br /> sediment pond. Magpie Creek will also be slightly re-routed to <br /> facilitate construction of the portal facilities and sediment <br />collection ponds. This restructuring of the lower part of the south <br />sub-basin should not significantly affect the small quantities of <br />dater contributed to Newlin Creek by the 1st south sub-basin. <br />Utilizing techniques described in the Colorado Geological <br />Survey Publication entitled "Manual for Estimating Flood Characteristics <br />of Natural-Flow Streams in Colorado" we have estimated the 100 near <br />flood parameters for the 1st south sub-basin in which the sine p~rta: <br />and spoils piles will be located. :'?tat portion of the 1st south <br />sub-basin lying above the outfall of the No. 2 sediment pond covers <br />approximately 1.4 sc.-miles and has an average basin gradient of <br />240 ft/mile. Utilizing these parameters we estimate a 100 year flood <br />• in this sub-basin ec_ld cause a floc: of up to 3200 efs in l:agpie Cree:; <br />at the portal site. It is estimated that flows of 5 feet in de?t'r. <br />,, would occur in Magpie CrEEk at the .portal site as a result of a <br />i00 year storm. The ?roposed embanicents along the re-route of <br />z_ u <br />