Seattle Highlights Rainwater Harvesting at ARCSA 2005
by Anitra Accetturo

July 13-15, of 2005 the American Rainwater Catchment Systems Association (ARCSA) hosted the North American Rainwater Harvesting Conference in Seattle, Washington. The three-day conference focused on design, installation, and components of rainwater harvesting systems featured in presentations and exhibits (see related article "ARCSA 2005: Focus - Rainwater Harvesting").

The first day of the conference was kicked off with an optional tour of rainwater harvesting systems in the Puget Sound area, featuring innovative and progressive water harvesting and sustainability techniques designed and utilized by the city.

The City of Seattle, with its abundant rainwater, has proven itself to be a front-runner in the field of innovative design and use of rainwater catchment, stormwater runoff reduction, and sustainability solutions. See the Spaceneedle webcam for live views across Seattle.

Seattle City Hall is a 20,000 square-foot building that was completed in 2003, and includes a green roof and rainwater harvesting (RWH) system for toilet flushing and on-site irrigation. These systems help reduce peak flows from the city drainage system and improve water quality by reducing the pressures on the city sewer infrastructure. The RWH collection system can store up to 30,000 cubic-feet of water in a cistern located in the basement of what was at one time the old municipal building. Collected rainwater is then pumped from the basement cistern to restrooms in the newly constructed City Hall building for use in toilet flushing, as well as irrigation purposes. Stormwater runoff is expected to decrease by up to 75% and reduce indoor potable water use by 30%. These measures result in a significant reduction of stormwater flows and will alleviate loads into the city's combined sewer system. The building has also earned a U.S. Green Building Council Leadership in Energy and Environmental Design (LEED) Silver rating.

The King Street Center is home to the King County Departments of Transportation and Natural Resources. It is a 327,000 square-foot building that was completed in 1999. Project highlights include a 16,200-gallon rainwater collection system, 80% of all construction waste recycled on-site, and 32,000 square-yards of reused/renewed carpet tile. The King Street Center would use approximately 2.2 million gallons of potable water a year for toilet flushing. With a 44,000 square-foot roof area for collection, it is estimated that about 1.4 million gallons of domestic water will be saved annually, or 64% of the flushing budget for the year.

The Carkeek Environmental Learning Center is a gathering space for environmental education activities and community meetings. It has achieved a LEED Gold certification, (the first Gold rating in Seattle), and serves as a model for resource-efficiency and sustainable building. Highlights of the building include a 3,500 gallon rainwater collection cistern used for toilet flushing and stormwater management, solar electric panels provided by Seattle City Lights Green Power program, 80% recycling or salvaging of demolition and construction waste, and use of regional materials manufactured and salvaged locally. Rain barrels were also installed on-site for irrigation of salmon-friendly native landscaping while being established.

Seattle's Street Edge Alternative Project (SEA Streets) was designed to provide drainage that resembles the natural landscape prior to development and traditional sewer and stormwater system installation. This entailed combining engineering concepts and designs with native soils and vegetation to assist in treating and regulating stormwater flows. The selected residential block for the pilot project had to meet specific criteria such as: a street that does not have existing curbs and sidewalks, located in the watershed area, and not directly served by the existing storm drain system. The pilot project began in 2001, and after two years of monitoring, impervious surfaces were reduced by 11%. Over 1,100 shrubs and 100 deciduous trees were planted, all native vegetation and hardy cultivars, resulting in a 98% reduction in total runoff volume. This successful project is now part of the Seattle Comprehensive Drainage Plan.

Seattle is home to many private and commercial rainwater harvesting sites. The above sites were toured by the attendees of the ARCSA conference attendees to educate and interest them in the possibilities for rainwater catchment and from the excitement of those taking the tour it was a great kickoff for the 2005 conference.

Anitra Accetturo is a Water Conservation Specialist for the city of Bellingham, Washington.