WSP07117 - Laserfiche WebLink

Home Browse Search

C":> CJ:> .-l c.;:.' ,::.,-) C) , CHAPTER II DESCRIPTION OF ALTERNATIVES diameter. Concrete pipe would be used for 30 to 42 inch portions of the pipeline, and PVC pipe would be used for diameters up to 30 inches. There would be three places (all located just west of the Clifton Interstate-70 (1-70) interchange) where the Stubb Ditch would deviate from the existing alignment. The abandoned portions of the Stubb Ditch would be filled in and recontcured to meet the existing ground to the extent that fill material is readily available in the immediate vicinity of the realignments. Recontouring efforts would not exceed the 70-foot rights-of- way width. Price Ditch.--The type of lining for the Price Ditch is likely to be concrete. A final determination of the peak design flow has not been made for the Price Ditch. The peak design flow is not expected to exceed 100 cts since this equals the total water rights for the Palisade Irrigation District. A more likely design flow is 70 cfs. The current flow in the ditch varies between 50 and 70 cfs during the irrigation season. Operational flexibility or severe rain storms could require the ditch to flow up to 100 cfs. At a capacity of 100 cfs, the top width of the ditch would be approximately 18.0 feet and the water depth in the ditch would be about 3.2 feet. At a capacity of 60 cfs, the top width of the ditch would be approximately 14.5 feet and the water depth in the ditch would be about 2.7 feet. Cross-Drainaoe Facilities Price and Stubb Ditches Cross-Drainaoe Facilities.--No new cross-drainage facilities are planned for either ditch improvement. Existing cross- drainage facilities, such as culverts, would be replaced in-kind when construction activities require their removal. East End Government Hiohline Canal Cross-Drainaoe Features.--The recommended plan in the Grand Valley FElS included crOSS-drainage facilities for the East End Government Highline Canal extending from the outlet of Tunnel No. 3 to Indian Wash. Cross-drainage facilities were to be constructed to protect the membrane-lined canal. The present cross- drainage facilities in the minor drainages, consisting of a series of culverts which are in poor condition due to age, siltation, and poor maintenance, would be replaced with a detention ditch and dike system according to tr.a FEIS. The cross-drainage facilities in the FEIS recommended plan for the East End Government Highline Canal consist of 6.5 miles of detention ditches starting about 3.5 miles downstream from Tunnel No.3, and two detention ponds to temporarily hold water, one located at Moulton Valley and one at Lewis Wash north of 1-70. Due to the heavy development between the Stubb Ditch and the East End Government Highline Canal, it would be necessary to locate these facilities north of the Interstate-70 (1-70). Studies since the completion of the FElS have indicated that a heavy rainfall in this general area could produce enough runoff between the proposed cross-drainage facilities and the East End Government Highline Canal, to cause the canal to fail. Since the costly cross-drainage facilities do not provide the desired protection and it is not economical to construct facilities closer to the canal, it is proposed to replace the existing cross-drainage facilities in-kind and 6