Don’t Waste a Drop! How Tech Helps Santa Monica Identify Where and When to Expand Reuse

As part of their Sustainable Water Infrastructure Project (SWIP), the City of Santa Monica (City) has committed to investing in recycled water infrastructure to serve non-potable and potable reuse applications. With the recently constructed first-of-its-kind Advanced Water Treatment Facility, upgrades to the existing Santa Monica Urban Runoff Recycling Facility, and newly adopted Recycled Water Ordinance and Guidelines, the City has demonstrated its dedication to developing an innovative recycled water program to reduce reliance on imported water supplies. However, the City’s existing recycled water distribution system is limited, and planned development is expected to grow significantly over the next two decades. A Recycled Water Master Plan (RWMP) is necessary to guide the planning of, and capital investments in, future recycled water infrastructure development. The focus of the RWMP is to document the City’s progressive strategy to utilize all available recycled water supplies for non-potable reuse (NPR) applications, groundwater replenishment, and potential future direct potable reuse (DPR) opportunities.
Kennedy Jenks worked collaboratively with the City’s planning, engineering, and operations personnel to define recycled water supplies and prioritize beneficial reuse opportunities. The use of recycled water for NPR applications, such as irrigation and dual-plumbing, in new developments is prescribed in the City’s new recycled water ordinance and is a critical component of their potable water conservation policies. A methodical alternatives analysis defined the highest priority development opportunities, coupled them with cost-effectiveness criteria, and analyzed alternative pathways to serve key customer areas.
An innovative Geographic Information System cost analysis tool was developed to guide the expansion of the City’s existing recycled water distribution system for NPR. A Radius of Cost Effectiveness (RoCE) approach evaluated the distance of expanded pipe required to reach potential NPR customers based on geographic location and demand. For the City, cost-effectiveness was defined by the City’s ability to recover the cost of providing service to a potential customer within a facility lifespan of 25 years. The cost savings were based on the difference in the cost of recycled water supply for NPR and DPR.
Each potential customer’s RoCE data was mapped to graphically depict the geographic cost-effectiveness. A circle representing the RoCE for each customer was super-imposed on the existing recycled water distribution system and identified “backbone” extensions. RoCE circles that intersect an existing or identified backbone pipelines are deemed to be cost-effective NPR customers. This visual and mathematical approach creates an unbiased method to quickly determine where to expand recycled water infrastructure.
The RWMP will provide a strategy for recycled water expansion and define a viable Capital Improvement Plan to support future City investments. As the need for recycled water becomes greater due to the impacts of climate change, the RWMP will allow the City to justify recycled water service to key customer areas, guide future collaborative discussions with developers in their planning processes, and ultimately aid the City in achieving their water self-sufficiency goals.