Gobernadora Multi-Purpose Basin
Orange County, California
PACE designed an innovative multi-functioning water infrastructure system that reclaims an urban stormwater waste stream and provides regional flood control benefits. The project was developed due to a successful partnership between Rancho Mission Viejo (original land owner), Santa Margarita Water District (SMWD) and Orange County Public Works (OCPW).
The 26-acre Gobernadora Multi-Purpose basin provides multiple functions including:
- Groundwater Recharge
- Groundwater Recovery
- Non-Potable Water Reclamation
- Flood Mitigation
- Urban Stormwater Treatment
- Stream Stabilization and Habitat Restoration
- Wetlands and Open Water Habitat
- Regional Trail Connection
This system is successful due to its dynamic hydraulic operating system design incorporating fully-automated controls that can respond to both low flow and high storm flow conditions in the creek. The system provides flexibility through multiple hydraulic systems including a dry weather nuisance runoff diversion structure featuring a rubber inflatable dam system to divert flows into water quality treatment cells, an elevated side weir to capture storm flows for peak flow storage, a secondary rubber dam for large flood flow water level control, and a pump station to transport treated flows for recycled water applications. The system’s design accommodates a projected 350 to 800 AF/year of dry weather flow recovery, provides storm flow detention up to the 100-year storm event.
The upper basin is operated and maintained by SMWD for water treatment and recycling purposes and the lower basin is operated and maintained by OCPW for flood control purposes. The upper basin allows urban nuisance (dry weather) runoff water to flow through multiple interconnected water quality treatment cells made up of wetland vegetation. The treated urban nuisance flows are captured by SMWD and recycled into their non-potable water system using a pump station in the upper basin. However, a portion of the treated nuisance flows is bypassed downstream to maintain a continued irrigation source for the Gobernadora Ecological Restoration Area (GERA). In addition, two groundwater wells are located within the perimeter embankment of the basin to capture part of the recharged groundwater in this area and connects to the same force main. Two large inflatable rubber dams are operated in the creek; the upper dam provides dry-weather flow capture and diversion; and the lower dam is for major storm event operation to divert flows to the lower basin.
During a major rainfall event, the diverted creek flood flows enter the upper basin and when the upper basin fills the flows overtop into the lower basin. The flood flows are uniformly distributed between the east and west cells of the lower basins from the intermediate spillway. To assist in this operation, a complex pump station facility located in the upper basin automatically controls the distribution of flows during dry-weather operation and operates the rubber dams during major rainfall events using stream gages and other sensors that communicate water levels to a controls system.
- Integrated water resources project
- Joint effort with three parties: Santa Margarita Water District, Orange County Public Works, and Rancho Mission Viejo
- Sustainability through unique water harvesting
- Dynamic system with automated water level controls in the creek
- Multiple basin configuration maximizing water quality and flood operation
- Unique geometry of large volume basin avoided Division of
- Safety of Dams (DSOD) jurisdiction
- Special mitigation measures for unique geotechnical conditions
- Multiple public grant funding sources due to water resource benefits