Ellis Creek Water Recycling Facility
Project: Ellis Creek Water Recycling Facility, Petaluma, CA, 12,790 square foot green roof
Green Roof Designer, Installer and Maintenance Provider: SYMBIOS Ecotecture (Award Winner)
Architect: Burks Loma
Engineer: Ingraham De Jesse
Plant Supplier: Emory Knoll Farms
Drainage System and Waterproofing: Tremco
Growing Media Base Layer: Rooflite
Irrigation: Hunter Industries
“‘Waste not, want not.’ Using reclaimed water to nurture the living roof is testimony to this proverb.”
– Kevin Falkerson, founder and principal, SYMBIOS
Wastewater Keeps Living Roof Green
The Ellis Creek Water Recycling Facility in Petaluma, California utilizes its operation and maintenance buildings to demonstrate the sustainable aspects of building integrated vegetation. The planting scheme of the living roofscape took advantage of the roof being visible from the surrounding roadways and landscape. The plants include 13 species of groundcover succulents, such as Summer Glory, Purpurteppich and John Creech. In addition, the facility is set along the banks of the Petaluma River and is adjacent to natural wetlands and constructed wetlands that are used to increase the quality of the treated wastewater before releasing it into the river. As a result of its location, the area is deemed as an avian habitat zone and the vegetative roof was designed in part to support the local and migratory bird populations of the area. The roof has been successful in this regard, as numerous bird species such as killdeer have used the roof for nesting.
The roofs are irrigated directly by utilizing the tertiary treated wastewater from the facility’s operations, which is held in a holding pond situated adjacent to the buildings. The treated wastewater allows the vegetation to be irrigated without the use of any potable water. Vines have been planted to green up the façade of the buildings. Stormwater overflow from the living roofs drain into ground level rain garden swales adjacent to the buildings for a net-zero stormwater runoff system.
The green roof is being used to support a native bee study research program (by Scott MacIvor, York University in Toronto) which is investigating the ecological importance of living roofs in relation to native bee populations. Weather data is also collected every month at the Department of Water Resources’ weather station. Water samples are collected, tested and recorded during the irrigation season.
In the western United States where seasonal drought is an annual event, this green roof project demonstrates the appropriate use of this reclaimed water resource. During the annual dry season (summer/autumn), the treated water is introduced into the City of Petaluma’s water treatment plant and used for irrigation of agricultural lands, two golf courses, vineyards and the treatment facility’s two green roofs. The facility currently processes over 700 million gallons of wastewater per year, which could theoretically support millions of square feet of green roofs.