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Ken Nelson <br />December 20, 2011 <br />Page 13 <br />toe drain and grout backfill, and 3) upgrade open ditch canal with closed pipe. Design criteria and <br />general construction details are listed below for each component of the improvement plan. <br />Design Criteria: <br />• 50 efs flow capacity <br />• 100-year service life <br />Inverted siphon 22 psi internal pressure <br />Tunnel liner conduit vertical loading 75 psi <br />• Provide drai cage from tunnel, separate from irrigation conveyance <br />Fill tunnel void outside liner Conduit <br />• Provide contingency to install air vent(S) it) tunnel liner conduit at high and low point(s) <br />• Install access manholes Outside the tunnel as a future contingency <br />Provide continuous, nominal slope for piped ditch with no sags or humps <br />• Provide traffic rated road crossings for piped ditch <br />• Provide cross surface drainage at piped canal an(] maintenance road <br />• Provide overflow along piped ditch upstream from tunnel <br />Provide a method for diverting flow (to overflow) prior to tunnel <br />• Maintain construction areas safe for personnel <br />ImProveLnents to Inverted Siphon: <br />• Remove and replace existing conduit with 54-inch DR32.5 HDPE <br />• Connect new pipe to existing concrete inlet and outlet structures <br />Install a drain assernblyat Tongue Creek <br />• Verify whether jurisdictional wetlands exist along Tongue Creek <br />Coordinate Highway 65 crossing with CDOT permit requirements <br />Improvements to Tunnel: <br />• For maximum service life with ad-equate future capacity, slipline with 63" HDPE DR17 <br />or <br />If higher level of future maintenance, monitoring and canal system management is <br />acceptable including possible future improvements to reduce natural losses <br />downgradient, slipline with 54" DHPE DR 17 <br />Install filter drainage toe drain along tunnel floor adjacent to liner plate <br />• Remove spilled debris, dragline, or as encountered by progress of liner plate installation <br />• Install air vent(s) at high or low point(s) in tunnel as necessary in the future <br />Install bulkheads at each portal, with 12" connection for toe drain <br />Extend 12 " drain pipe from toe drain at each tunnel portal bulkhead to daylight discharge <br />