C150104 Feasibility Study - Laserfiche WebLink

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I I I I I I I I The Peterson Ditch is decreed for 534 cfs under two separate decrees, but the diversion records for the past eight years indicate that 101 cfs was the maximum diversion that has occulTed. The second decree, which is junior to the compact, has not been utilized and is on the list for abandonment. The operator of the ditch indicated that there also is a possibility of diverting flows for this project via the Peterson Ditch during the spring runoff. Diversions during the spring runoff period would not be consistent, due to the fact that diversions would be dependent upon the available capacity of the ditch after the ditch shareholders flow requirements were met. An alternate to allow diversions when shareholders are using the capacity of the ditch is to enlarge the capacity of the ditch in the reach from the river to the reservoir to accommodate the junior fill decree of the reservoir. This would insure no injury to pn~sent users under the ditch. It is estimated that an enlargement would run between 30 to 50 cfs of capacity. There are many issues associated with this that need to be addressed. The Jules berg Irrigation District is key in any use of this structure and will need to give approval for any proposed modifications. This alternate will need further study during the preliminary design phase. I I The present configuration of the Peterson Ditch diversion structure is capable of diverting all flows from the main stream of the South Platte River up to ditch capacity. The structure is a wood sheet pile structure with a concrete cap. The structure for the Pt:1erson Ditch is apparently in poor condition and there is a concern that the structure is in need of replacement. The general concern is that the streambed is degrading downstream ofthe structure, which eventually could cause the structure to fail. It is unknown at this time if any corrective action is slated to repair or replace the diversion structure. I The location of the Peterson Ditch, and the fact that the ditch would be able to provide a gravity supply, make it ideal for a water supply source for the proposed reservoir. Although the Peterson Ditch will not be capable of filling the reservoir to the high water line, the ditch will be able to fill approximately 75% of the reservoir's capacity, efficiently .and cost effectively. I I I Certain limitations are associated with using the Peterson Ditch to deliver water to the reservoir. The diversions through the Peterson Ditch will primarily occur during the winter months when sub- freezing temperatures are possible. Freezing temperatures could prevent diversions due to icing and the possibility of ice jams. The timing of diversions may help eliminate this problem. There is a fairly lengthy time period during the winter months when the flows in the river are high enough to support this re-regulation project. It appears there is sufficient time in moderate temperatures to divert a full supply to the reservoir. I I I I I The second option for diverting flows into the reservoir are the GASP "Ovid Wells" which are located directly south of the proposed site (See Figure 2). The three wells were originally constructed in 1977. The west well was washed out by the river and was replaced in 1984. The wells as they are presently equipped are capable of delivering 20 cfs (8980 gpm) to the reservoir site under the following technical assumptions listed in Table 1: Table 1 - GASP Ovid Wells Technical Data Conditions of Service (COS) Well Identification Casina Size PumD Motor Discharae Total Dvnamic Head Efficiencv West Well 18" 16" - 1 Stage 100HP 3750 ~mm 85 feet 84% Middle Well 16" 14" - 2 Stage 60HP 2750 ~~Dm 85 feet 83% East Well 16" 14" - 2 Stage 60HP 2750 ~'nm 85 feet 83% 5