Walla Walla creates smart DMA's in two months using existing infrastructure
In Western Washington State, Seattle and Tacoma receive plentiful rainfall to fill their reservoirs. On the arid East side of the state, water isn’t as reliable. Located East of the Cascade Mountains and West of the Blue Mountains sits the town of Walla Walla, which depends on unpredictable mountain snowpack for water supply. Water is in high demand due to agriculture in this area, and supply varies from year to year, making water conservation a top priority.
The city has two sources of water. The primary source is a 36 square mile area forming the Mill Creek watershed, the secondary source, is seven deep (800-1400') basalt wells used to supplement supply when stream levels decline in the summer months. Water from Mill Creek is piped 14.5 miles to the city's water treatment plant that can produce 24 million gallons of water daily. All water that passes through the treatment plant from the Mill Creek watershed also passes through a hydropower generator which produces 13,500 megawatts of electricity annually (sufficient to power approximately 1,500 homes).
Like many cities, Walla Walla has struggled with non-revenue water (NRW) loss for decades with some years reaching as high as 40% loss. In 2010 the city instituted a part self-imposed, part government-imposed initiative to reduce its NRW. By 2022, the city had reduced NRW to 13.4% and set an ambitious goal to reduce water loss to below 10% by 2028. In addition, the city wanted to reduce pipe breaks, create calmer and balanced networks, and institute multi-stage pressure management. All of which would enable improved distribution with fewer leaks and lower NRW.
Most NRW is due to leaks, but not all NRW is due to leaking pipes. For example, flow may show you a potential leak, but the pressure will show you the system changes that may have affected the leak. Locating leaks in a distribution system can be overwhelming, expensive, and only tell part of the NRW story. Ensuring accurate flow readings throughout the district can improve NRW statistics as well. It is important to ensure equipment is up to date to gather as much system data as possible to make informed decisions.
Walla Walla decided to do what many water districts have done, and create district metered areas or DMA’s to monitor and “see” into their system. DMA’s can help identify areas with unusual water flows at any time of day or night. DMA’s can also help identify zones that use more water than others and why.
The city has five pressure zones and 200 miles of watermains with 12,000 connections. The process to build district metered areas can take upwards of 3-5 years and cost millions of dollars. In early 2022 Walla Walla worked with Cla-Val, supplier of the city’s automatic control valves, and Sensus, supplier of the city’s AMI system to see if they could work together to use existing infrastructure to create smart DMAs.
For the first pilot, the Cla-Val XP2F system was installed on a nine-year-old automatic control valve in the spring of 2023 using solar power and integrated with the Sensus FlexNet communications system. This data instrument package retransmits flow, pressure and valve position data to SCADA or AMI networks via 4-20mA signals or pulse output. Flow and valve position data can provide leakage and system dynamics to create a balanced network. Walla Walla is using this data to adjust water movement to improve chlorine residuals. Pressure data can provide proper system working operation information and insight into high/low/surge pressure irregularities.
Once connected, the city could immediately see real time flows, pressures, and the valve position in the DMA. The flow rates were within 1% of accuracy.
Adrain Sutor, Water Distribution Supervisor for the City of Walla Walla said, “By converting our existing PRV’s into meters for measuring flow, we can see exactly what is happening in these DMAs. We can quickly identify irregularities and address the issue.” In many cases this can be leaks, but irregularities can also be faulty meter readings. Part of Walla Walla’s NRW initiatives involved working with Sensus to update aging metering infrastructure and implementing the XP2F which can read flow rates on mains.
Walla Walla used federal grant money to retrofit all 28 existing control valves with the XP2F instrumentation package. The project was funded through the WaterSMART Small-Scale Water Efficiency Grants, program with the Bureau of Reclamation that provides 50% cost share of projects. Within two months Walla Walla’s water distribution system was online. The overall cost of installing the instrumentation package was $211,746.
“When we first began addressing our NRW in 2010, we were losing 1.2 billion gallons per year. We initiated leak detection, repairs, and updated our meters. This brought our NRW down to 13.4%,” said Sutor. “It took us 3 weeks to bring our valves “online” using the XP2F system with our existing communications system. We can now see which zones need addressing to reach that critical 10% by balancing flows to each zone and through further leak detection and pipe repair. I wish we had this technology back in 2012!”
Upon initial implementation of XP2F system, Walla Walla noticed a large discrepancy in production vs consumption in “Zone 1” of their system. The discrepancy was throwing off flow readings system-wide since this is the lowest zone from where water enters their system. They were able to isolate this zone further and pinpoint several leaks, including one large 65 GPM leak which was bursting from the entire circumference of the pipeline. Walla Walla repaired the leaks after 70+ years of non-compliance, and is now operating under 10% non-revenue water, which was their goal by 2028.
This small town of 34,000 people is now leading the way in rapid creation of smart DMAs, that was once cost prohibitive for smaller districts and even some major metropolitan systems. The combination of the affordable retrofit metering connecting with existing AMI or SCADA communication systems, has the potential to quickly and cost effectively manage and conserve water usage around the world.
“Thanks to the WaterSMART fund and the XP2F; it is quite affordable for water districts to convert existing infrastructure into smart infrastructure thereby reducing NRW in a relatively short time. The grant is available for projects that include installation of flow measurement or automation in a specific part of a water delivery system,” said Jake Corzine, Regional Sales Manager for Cla-Val.
About the Author
Steve Causseaux
Steve Causseaux, district sales manager for Cla-Val, has almost 2 decades in water management. He works closely with water and wastewater district operators, engineers, and independent engineering firms to select valves and specific valve functions for a wide range of applications.