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The section of channel between ~ississippi AVe. and Garrison St. is essentially formed by filling the surrounding area to render it developable. The entire area is presently in the flood plain due to its elevation several feet below the sur- rounding streets. Construction easements should be obtained in these areas to allow the placement of fill obtained from other excavation areas in the project. The culverts beneath Garrison St. are designed to carry slight- ly in excess of the 10 year storm runoff. Although the City of Lakewood had asked for greater capacity beneath Garrison, it is impractical to install larger conduit at this point, since runoff in excess of the 10 year capacity would mainly be flOW- ing on Mississippi Ave. and would not reach the conduit be- neath Garrison St. The area northwest of the Garrison St. culvert should be filled to a minimum elevation of 5551.0 to prevent flooding by the backwater from the Garrison St. crossing. The master plan does not deal directly with the local drainage problems of the Mississippi and Garrison intersection, although ccrtain information was developed and should he conveyed to those involved in design of storm sewer in the area. The grades surrounding Mississsippi Ave. are such that a significant accumula- tion of flow on Mississippi will occur regardless of what is done to the main Weir Gulch Channel. Portions of the flow will be diverted at the Mississippi and Garrison intersection going to the north and south and ontering the two gulches located either side of Mississippi. Other portions of the flow will continue across the crown of Carrison St. and provisions should be made for allowing them to continue into the gulches,on the east side of Garrison. The existing conduit beneath GarrLson St. north of Mississippi is seriously undersized and should bc increased to accommodate the flows indicated on the master plan shoet. Between Garrison St. and Hoyt Street the existing gulch tlows through a man-made channel in a 30 foot right-of-way. The recom- mended channel cross section through this area consLsts of an open drainageway with a 3:1 side slope and a l,l side slope with a gabion lining. The proposed improvement for Hoyt St. is the insta~lation of a reinforced concrete box culvert capablo of carry Lng the 10 year storm runoff. Large grated inlets should be,placed on top of the culvort to intercept surface runoff flowLng along Hoyt St, without overtopping the street. Storm flows greater than the lO year storm flow will not totally reach the crossing. When the street is overtopped, the flow leaves the gulch and runs south to Arizona Avenue and reenters the gulch at Hoyt Street. Above Johnson Way is the Agricultural Ditch wasteway and over- flow structure, This structure will be used as the outfall point of the 54 inch storm sewer which parallels the ditch from Mississippi Avenue. The sewer is sized for a 10 year capacity and should be located on the €ast side of the Agricultural Ditch 40 foot right-of-way, under the access road. At Mississippi Ave. and Agricultural DitCh, a grated inlet is proposed to intercept stroet flow generated below Kipling. Also, a junction box is provided on the east side of the ditch for the new and existing storm sewers paralleling Mississippi belOW Kipling. The storm sewer and ditch crossing can be accomplished by providing a 2' x 8' concrete box for Agricultural Ditch under Mississippi. The depth of flow in the box will be shallow enough to permit the sewers to pass over the top of the ditch without constricting ditch flow. At Kipling and Mississippi, inlets are provided to ~he two par- , allel storm se~'ers, sized for a 10 year storm capacLty. 1\lx:.lve thLs point, Mississippi Avenue should be extended to the base of the ~ain Reservoir spillway with provisions to accept the 100 year spill from the reservoir of 350 cfs. Between the street and the spillway stilling basin, a lined channel should be installed. Main Reservoir and the existing spillway have been designed to accommodate the probable maximum storm occurrence as required by the State Engineer. East Reservoir presently has a new spillway upder design which will also <':omply with State Engineer require- ~,,)nts. West of a cross Hoyt St. the channel continues in a ~o foot easement with section similar to that between Garr~son and Hoyt. Drawing No. NW-l North Weir Gulch discharges into a separate portion of Main Reser- voir located at the north end of the reservoir proper. Flows entering this portion of the reservoir have historically been diverted to the return ditch or to Main Reservoir via two irriga- tion control gates. A positive method of discharging flow from North Weir Gulch into Main Reservoir must be constructed so that floc~ ~ate~~ c~nnet co~ti~uc to the east in the historic N~yth Weir Gulch channel. Drawing No. W-13 The channel section recommended for 1>"10'",, and above Johnson Way is the same as that discussed on Drawing w-12. The cross- ing at Johnson Way was designed for the 10 year frequency storm West of Main Reservoir, weir Gulch flows which are indicated as flood plain zoned through undeveloped lands areas. Drawing No. 1>.111-2 Weir Gulch flows through public ownership in a very deep, steep ," -......~- '" -.........-