Cherry Creek Diversion Facility

Challenges

Rueter-Hess Reservoir was developed by Parker Water & Sanitation District to serve as a regional raw water storage facility.  The facility consists of an “off-channel” reservoir located on Newlin Gulch, a tributary to Cherry Creek, and is primarily filled by diversions from Cherry Creek.

The Cherry Creek diversion consists of a diversion dam and pump station on Cherry Creek with the ability to divert up to 78 cubic feet per second (cfs) through a 48-inch-diameter ductile iron pipeline approximately 3 miles to Rueter-Hess Reservoir.  Technical challenges to implement the diversion included a diversion dam on a meandering stream, elevation changes of over 100 feet, crossing several drainages and roads, topographic constraints, and geologic considerations.

Solution

The diversion facility was designed and constructed in two phases.  Phase I included the diversion dam, pump station, and an approximately 15,000-foot-long pipeline.  RJH staff provided technical review and guidance for geotechnical issues associated with the diversion dam that included sedimentation and underseepage.

Phase II included an additional 1,500 feet of pipeline, a reinforced concrete outlet structure, a riprap-lined upper discharge channel, and an unlined lower discharge channel in the reservoir.  RJH provided design and construction engineering services for Phase II.  The pipeline is subject to pressure surges from pumping, and a combination air-vacuum valve was installed in the Phase I pipeline to mitigate pressure surges.  RJH performed transient hydraulic modeling as part of the Phase II design and identified that a 48-inch-diameter open standpipe would also be required to ensure the pipeline was within acceptable pressure allowances.  The outlet structure was designed to create a plunge pool within the structure to dissipate energy when the reservoir pool is low.