Coachella Valley Water District
Coachella Valley Water District (CVWD) operates a groundwater replenishment facility in the Whitewater Flood Channel. Although a floodway dike protects the groundwater recharge ponds from the flood flows through the Whitewater Flood Channel, the remainder of the system has been operated in the Flood Channel, proving problematic. Flood events in the Whitewater River channel have caused severe damage to the facility's intake channels and sediment basins resulting in a constant maintenance effort. Following a major flood event in 2009, operations abandoned the sediment basins located in the Whitewater channel. Since that time up to 20,000 cubic yards of sediment per day has been entering the recharge ponds through the existing intake structures limiting the Facility's recharge capacity.
Dahl Consultants is serving as the design engineer for this project. An initial analysis was completed to determine the ideal location of the diversion channels; inside or outside the floodway dike. The evaluation, which showed that moving the channel inside the floodway dike was the most effective solution, considered channel hydraulics, permitting, future flood risks, schedule, construction costs, amount accomplished with initial funding, and operations during construction.
The design consists of a single intake/sluicing structure from the river into the facility, two diversion structures within the facility, and 12,000 feet of conveyance channel. The intake/sluicing structure is designed to allow flows with high sediment content to bypass the facility so the sediment would remain in the Whitewater River Channel. The structure includes a single radial gate for sluicing, an overflow weir for flood protection, and two gated intake boxes through the flood dike. The two diversion structures are designed to create three independent sections of the recharge facility, providing the District maximum flexibility for operations and maintenance of the Facility. Diversion Structure 1 was designed to isolate section 1 and allow the full 800 cfs design capacity to pass through to Diversion Structure 2 or split flows between section 1 of the Facility and Diversion Structure 2. Diversion Structure 2 was designed to isolate either section 2 or section 3 of the Facility or split flows between the two sections, 400 cfs to each.