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v 11-6 The channel below the Calkins Ditch hE'ildgate sho~ln on Sheet 15 needs the addition of large rock dlsslpators to break up the jet that could cause considerable erosional damagE dO~lnstream of the headgate, even for frequently occurring storms. Due to urbanl.zatlon, the, low frequency storms wi 1 I have much greater runoff peaks ,and vo I umes and the rate of erosion downstream of the Calkins Ditch heCidgate ,,,Ill be considerabiy accelerated. The existing 112th Avenue bridge is to be replaced with a brIdge 75 feet wide, and as In the case with all other brIdges within the area, the low point of the roadway Is not to be locat.ed over' the bridge. The purpose of th Is requ I rement I s to cause washouts to be loc,ated In the road embank- ment so that structural damage to the bridge is minImized, even though the bridge Itself may also be somewhat overtopped. The Sheridan Boulevard embankment shown on Sheet 22 poses a hazard to life and property in the event that It Is washed out. There are presently two culverts nine feet In diameter through the embankment, and they do nclt have sufficient capa- city to pass the des Ign flood of 8800 c1's, The lrnpnlvements proposed Incl ude: I. RaisIng the embankment to elevation 5261.5. The low poInt is to be located on the south side of the flood plain 50 that erosional damage Is limited to an area that wi I 1 not cause a sudden relMse of a large volume of water. The downstream face of the ,embankment Is to be pro- tected with burled broken concrete or the reg'.t1ar dumped rock rlprap. 2. Two new 10' x 17' box culverts are to bEl added at a substantially higher elevation than the two existing culverts. The purpose of this Is to allow pedestrian passage and to allow for construction of the new facilities without closing all of Sheridan to automobilE, and truck traffic. 3. Both the new box cu I verts and the ex 1st i ng 9-f,oot oct I ameter pipe are to have head walls, wing walls, and an entrance suitable to provIde an entrance coefficient equal to 0.2 or less. Data are available In Federal Highway Administration Hydr.;lullc Englneer'lng Circular No. 13 for the design of the entrances. 4. Both the proposed and the existing ';ulverts wi i i ..equlrE' energy dlsslpators. 5. A shallow V-shaped channel or swale Is to be constructed from the new box culverts to the existing channel do~'nstrellJll of Sheridan Boulevard. The presence of the concrete median barTler On U. S. 36 (Denver- Boulder Turnpike) causes an Increase in the flood ,elev'ltlon of nearly two feet. It Is proposed that 500 feet of the concreto. median barrIer be re- moved and replaced with a post and rai 1 type steel ban"ler and that the