Spring Mountain Ranch Flood Protection & Urban Drainage System Facilities

Riverside, CA

PACE was responsible for the design and preparation of construction documents for 4,000 lineal feet of open channel including; nine drop structures, three box  culverts totaling over 2,600 lineal feet, two debris basins, approximately 5,000 lineal feet of storm drain system, and a baffled chute energy dissipation system. Unique hydraulic design solutions were developed for this project addressing physical constraints and environmental mitigation requirements. 

The Spring Mountain Ranch (SMR) development is located in the Highgrove area of Riverside County near the City of Riverside.  The proposed master planned community consists of approximately 1500 single family homes, along with some commercial areas and a future school site.  The tributary drainage area for the project is approximately 2,300 acres.

The baffled chute energy dissipation system was used at the downstream end of the project to minimize flow velocities at the project boundary.  One of the reasons for reducing the flow velocities was to prevent the disturbance of the 108” diameter California Aqueduct Pipe, which crosses underneath the drainage course immediately downstream of the project boundary.

The debris basins were designed based on the criteria set forth by the Riverside County Flood Control District.  The first of the two debris basins has a depth of approximately 16 feet, and a design capacity of nearly 15 acre-feet.  This particular basin is located at the southeastern end of the project and has a tributary drainage area of nearly 700 acres.  The second basin has a depth of 10-feet and a design capacity of about six acre-feet.  This basin is located at the eastern end of the project and has a tributary drainage area of 243 acres.  One of the major issues associated with the debris basins was finding a location for the facilities without making major adjustments to the development plan.  Much of the development had already been designed when the developer was informed of the requirement for debris basins, therefore the debris basins had to be designed to fit within the proposed development plan.