PROJECTS

Rancho Wash Detention Basin is located near the upstream end of the Rancho Wash and functions as part of the City of Rancho Cucamonga’s flood control system. The basin captures and conveys runoff generated on the north side of Hillside Road through a reinforced concrete pipe, which crosses under Hillside Road and discharges into the upper reach of Rancho Wash. Rancho Wash is a concrete-lined flood control channel that continues downstream until it converges with the Demens Creek Channel within Heritage Community Park. Following this confluence, the combined flows are directed into the larger Cucamonga Creek Channel system. This interconnected network of the detention basin and channels is designed to manage stormwater from the surrounding foothill areas, reduce the risk of flooding, and safely convey runoff through developed portions of the City.

The project increased the detention capacity of the existing basin through major excavation, installation of reinforced concrete bottom slab and retaining walls at the standpipe, and construction of a riprap field designed to reduce the flow velocities, capturing sediment, and help keeping downstream channels clear of debris. The regraded basin side slopes were stabilized with hydroseeding to reduce erosion and promote vegetation growth. In addition, an access path was constructed to provide maintenance access to the standpipe, improving the ability to remove accumulated debris and supporting the long-term operation of the basin.