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::'!~", ~"mp m~;ntenance of the channel diversion mai" be required; however, the diver- sion will safely pass the f100d events. Velocities for the IO-and 50.ywevcnts average 4 and 6.5 feet per second, respectively, Plate 8 shows the typical cross section of th~ diversionchanncl. Mannings"n" value for the channel diversion was assumed tobc 0.035. Eleven l2.footby 6-footby 195.foot-Iongconcn:tc box culverts would con\i~y the channel diversion flows through Willox Lane and the UPRR for the lOO-year plan, and four 12-foot by 6-foot concrete box clllverts wOl.lld be required for the 30-year plan. Design and construction requircments for the concrete box culverts under the railroad were coordinated with the Union Pacific Railroad, t!;er~!r':'1d. BO'" "ptinn, were more expensive than the selected plan becallse of added rcal estate relocations, easements, and higher construction costs. All maintenance, repair, and replacement costs for the new box CI.Ilverts would be the responsibility of the sponsor. Negotiating these agreements with the UPRR will be the responsibilily ofthc sponsor. The concrete box culverts will be constructed in two phases. Willox Lane will bc temporarily detoured to thc north of the construction during both phases ofconstfllction, At the beginning of the fif5tphase, the railroad will bc temporarily relocated to the west by constructing a railroad shoefly. AU railroad track eon~tructi(ln and ballast construc- tion excluding earthwork (cut.fill and grading) will have to he aeeompjishoo by the UPRR. The cost of this work will have to be paid to UPRR undcr a cost reimbursable contract. AfteT the first pha<>c of the box culvertconstructiol\ iseomplcted,th erailrood will be reconstructed in its original alignrncnt uver tli" new box c\ilvert. The sec,'nd phase of the box culvert construction will then be accomplished. Willo,", Lane will ~ recopstn,clt'.d after the sec\l1\d pha>e ofeonstruction iseompleted, From WiIlox Lane to thc Cache La Poudre River, the slope of the diversion chan- nel would be 0.00413, Upstream from Willox Lane, the slope would be 0.0034. The diversion channel would be about 5,650 feet in length. A Texas crossing would be required across an existing road approximately 1,200 feet from thedownstre.,m end of the diversion channel. Earthen berms would be required, beginning approximately 50 feet downstream from the Texas crossing for a length of approximately 1,700 fl'Dt. These bcrms would be located in a low area of the channel alignment and would prevent the applicable loo-year or 30"year flows from flooding adjacent low areas, The berms would have a top width of 10 feet and I V on 6H sideslopes and would average about 1,5 feet in height, ineluding I foot of freeboard, 1'.....0 alternate channd alignments were discussed with UPRR and were investiga. ted. The first option .....as to shift the channel alignment to the northwest. This would req:nrc three neW bridgcs or three new box culverts at Willox Lane, tl1e railT\lad linc, and the road cast of the railroad. The second option would \\se the original channel alignment, construe! a bridge on the railm;\o line a~ Willo, Lane, construct an overpil's on Willox L1ne over the railwJrlline, and constmct a bridge on the wad to the e<l~t of Riprap would be placed at the downstrcam end of all boxcul\ierts and at the Olltlet of the diversion chilnnf'J into the Cache La Poudre River. Riprap would also be placed upmcilm and downstrt".am from thc Larimer and Weld Canal crossing and at the diver- Slonweir. RL'\L ESTATE SEeTlO:'\' The Real ESlate imerestllscd for lh\> stlldy was fee title for the diversion channel with a 15"foot-widc temporary wurl.: area easement moning along t\1ch ~ide the prop<.1'<Cd channd. The alignment for the 10Cl-year and 30-yeM diversion ehanncl~ arc virtually the b~3 ~,