Client: Sacramento Municipal Utility District
The Sacramento Municipal Utility District was designing a new 51-acre East Campus Operations Center that was to be “green” in every way practical. According to Gary King, chief workforce officer at SMUD, “The project will serve as a nationwide model for customers and public utility leadership peers in the ongoing sustainability movement.”
In addition to photovoltaic and thermal solar panels to provide a source of on-site renewable energy, planners wanted to make efforts to conserve water by evaluating options for on-site water reuse. Stantec Architecture and Intech Mechanical teamed up with Wahaso to evaluate and deliver the best option for a system.
System Type: Greywater for Toilet Flushing
Commissioning Date: Fall, 2013
Challenge: Wahaso worked with two different design teams to identify the optimal water reuse options. Possible sources included rooftop rainwater, cooling tower blow-down reuse and greywater. Sacramento's climate is arid, and the cost of storing sufficient rainfall throughout the dry season was cost prohibitive. And there were concerns about chemicals and dissolved solids in the blow-down. Space for water storage was a real issue. Demand for toilet flushing was about 450 gallons per day with a much greater demand for irrigation water.
Solution: The team decided to collect greywater from the bathroom lavatories and locker room showers to flush toilets in 22 of the 75 total water closets. This was due to restrictions in the mechanical layout that made it impractical to plumb all toilets with processed greywater. Excess greywater was stored to supplement the irrigation system. Wahaso recommended its patent-pending greywater processing system and controls.
Results: The SMUD building should be commissioned later in 2013 - but Wahaso's system is installed and ready to go. Once the building is operational, the system should save 150-200,000 gallons of municipal water annually.