Design / Operation of an Innovative Multipurpose Detention Basin Maximizing Stormwater Reuse - Gobernadora Basin

Date / Time:
Wednesday, Sep 14 11:35am to 12:05pm
Bay View
Track / Session:
Stormwater as a Resource / Fostering Stormwater Capture
Short Description: 
Case study of a multi-objective detention basin, the Gobernadora Basin, an extremely unique stormwater reclamation facility with highly specialized design elements and numerous benefits.

Purpose: Present a case study of a recently completed unique multi-objective detention basin with several benefits including recycling of urban nuisance runoff as a non-potable water resource. Main Ideas: Stormwater capture and reuse facilities are becoming more common, particularly with the value of water emphasized with drought conditions in Southern California. However, most conventional stormwater basins have a “static” design to respond to a single flow condition, or require manual operation to adjust operations. A case study of a recently completed multi-objective detention basin in Southern Orange County, the Gobernadora Basin, illustrates an extremely unique stormwater reclamation facility due to the highly specialized design elements and the numerous benefits generated. A key feature of this system is its dynamic hydraulic operating system incorporating fully-automated controls that adjusts to flow measurements in the adjacent main creek. The system provides flexibility through multiple advanced technology hydraulic systems responding to both low-flow and high-storm flow conditions in the creek. Summary of the Tools, Ideas and Concepts: The constructed 30-acre detention basin is situated adjacent to a natural alluvial creek that drains a highly urbanized 7.8 square-mile watershed. The basin reclaims and treats urban stormwater runoff from the creek system diversion to an extensive naturalized treatment system that is pumped to a reservoir for later use and a well system to also capture the stormwater groundwater recharge. The basin system was planned and constructed to provide multiple functions for this basin include: 1) flood mitigation, 2) urban stormwater treatment, 3) groundwater recharge, 4) groundwater recovery, 5) non-potable water reclamation, and 6) stream stabilization and habitat restoration. There are numerous physical and regulatory constraints were overcome to achieve the maximum benefits from this site including existing wildlife habitat, active alluvial creek system, high groundwater, topography, existing utilities, adjacent public park, and residential area. The facility is configured with two basins, an upper basin of 13 acres and a lower basin of 17 acres, interconnected by a spillway system. A specialized side weir located in the upper basin and adjacent to the creek allows peak storm inflows into the basin while bypassing sediment downstream to the natural alluvial channel while also minimizing disturbance of the creek. The upper basin also includes a low-flow diversion from the creek for nuisance flow and multiple interconnected water quality treatment cells that provide treatment of urban nuisance flows generated from the upper watershed. The treated urban nuisance flows are captured and reclaimed into a non-potable water system using a pump station that connects to an existing force main nearby. 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 connect to the same force main. The flood control function is provided by the available storage volume contained in the upper and lower basins. Two inflatable rubber dams provide the hydraulic control in the natural creek; one for dry-weather flow capture; and the second for flood operation to develop variable water levels for the side weir. This project provides an excellent example of a stormwater reuse/treatment facility with advanced design elements to allow dynamic operation and has received multiple grant funds because of the unique benefits. Interactive Experience: 1) demonstration of how a design process is applied to an actual case study, 2) presentation of in-field photos, 3) high level custom graphics to illustrate key points, 4) drone video of case study in operation, 5) providing attendees magazine-style handout illustrating key presentation take-aways. Conference Theme: Unique stormwater recycling application

Primary Speaker:
Bruce Phillips, PACE Advanced Water Engineering