Dry Weather Flow Capture and Potable Reuse
Dry weather runoff in urbanized channels in the Los Angeles area accounts for a significant annual discharge with an average flow rate of approximately 153cfs in the Los Angeles River alone. With California’s current drought, water is at a premium. SB 985 requires water agencies to consider dry-weather water capture in future water-saving plans and water-recycling projects. In most cases, dry weather flows are diverted to the sanitary sewerage system or infiltrated for later withdrawal, but not currently available as a potential drinking water resource due to water quality issues, a lack of regulatory framework, and insufficient infrastructure. This presentation will explore the feasibility of using dry weather runoff as source water for potable water supply or non-potable uses with options including: collecting the dry weather flows to sell as grey water, collecting and injecting for later groundwater withdrawal, collecting and pumping to spreading grounds and treatment, and advanced purification for potable use. This presentation will evaluate the potential collection of Los Angeles River dry weather runoff, diversion to an advanced purification system, and distribution into the potable system. Considerations presented will include: water chemistry and flow rate; distribution risks; operator certification needs; potential downstream receiving water health and eco-system disturbances; and public perception challenges. Lessons learned from the development and implementation of advanced purification of wastewater for potable reuse will be discussed in the context of overcoming potential challenges for the implementation of dry weather runoff capture and reuse.