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Urawing No. S-S The existing conduit beneath Lowell Blvd. shall be left in place and excess flows allowed to flow across the street surface. No property damage is expected from the flow across the street sur- face. west of Sheridan Blvd. so as to permit acceleration of the flow into the culvert. West of Lowell the channel continues through the strip park devel- opment of the Denver Parks Department. The only improvements necessary in this area consists of the installation of check dams to control channel velocity and the suggested removal of the exist- ing pedestrian bridges as mentioned above. The check dams again may function as pedestrian bridges across the gulch. From Sheridan Blvd. to the alignment of Depew St., the gulch flows through the Bit-Q-Sea development area. Two recreational pools have been constructed on the channel to form the core of this development. The proposed improvements in the area are as minimal as possible while assuring the stability of the drainage facili- ties. Drawing NO. S-6 The existing culvert beneath Tennyson St. shall be left in place and excess flows allowed to flow across the street surface. Some local flooding will be encountered for the 10 year and less fre- quent storms. The property damage potential, however, does not justify the installation of a new structure beneath Tennyson. The channel between Tennyson and Xavier flows through an area with relatively narrow public right-of-way. Portions of the reach will employ 3,1 side slope channels and the very narrow portions will utilize a 1;1 and 3,1 side slope Channel with gabion protection on the 1,1 slope. The existing embankment to the larger Bit-Q-Sea Reservoir should be raised and the spillway improved to prevent breaching of the dike during major storm occurrences. The entire dike should be designed as an overflow embankment to meet the State Engineer criteria of passing the probable maximum precipitation runoff. An alternate plan would be to leave the embankment elevation at its present elevation and lower the water surface of the reser- voir 2.2 feet by lowering the spillway crest elevation. An elevated sanitary sewer crosses the channel at t.he alignment of Depew St. This crossing may be left in place if sufficient slope protection is placed around it. The low point in Xavitlr SL. does not coincide with the gulch cross- ing, but rather is situated at the intersection of Colorado Ave. "nd Xavier St. The result is that overflow of Xavier St. contin- ues to the south and thence easterly along Colorado Ave. result- ing in significant flooding of the area. The master plan calls for installdtion of a box <:n..llvert Lo !'epldce the existing cross- ing. Limited flooding would still occur during a major storm occurrence but property damage should be kept to a ~inimum. The master plan calls for improving Clairfield Reservoir as a flood detention facility capable of storing the 100 year storm runoff without overtopping of the berm. The present spillway should be relocated to an alignment consistent with the channel thalweg. The embankment Rhould be raised 2.0 feet to meet the State Engineer criteria for dams. The reservoir may stay in private ownership if acceptable agreements are obtained to in- sure its continued existence as a flood detention facility. The site would ~lso lend itself to an excellent park development in public owne~ship. Drawing No. S-8 Between Xavier St. and Sheridan Blvd., the channel flows through an area with very narrow public right-of-way. Here a channel cross section utilizing a 3,1 side slope and a 1:1 side slope with gabion slope protection is recommended. A paved invert should be installed in the channel cross section to allow for access along the channel. Between Clairfield Reservoir and Jewell Ave., the gulch is to be flood plain zoned with no improvements recommended except for approximately 100 feet of channel reshaping below Jewell Ave. Dr<lwing No. S-7 An improved crossing of Jewell Ave. is designed to pas!! the 100 year flow totally beneath the street. Channel improvements are necessary between the Jewell cross~ng and the Shwayder Ponu to intercept th", wide flood plain area extending belo".. the pond. Shwayder Pond may be left in its existing condition, although improvements might be initiated by its owner to prevent over- topping of the eIT~ankment by frequent storms. The Green Gables Country club entrance road becomes an important aspect of the entire storm drainage system on Sanderson Gulch. The existing culvert under Sheridan Blvd. is capable of passing the 10 year storm runoff if its entrance is improved to develop the maximum culvert capacity, This would require the lowering of the spillway from an existing recreational pond situated just -~~- -97-