Storm water management
Every year in Portland, approximately 10 billion gallons of rain falls upon hard surfaces like streets, parking lots, and rooftops. Most of these surfaces are impervious—they don’t allow water to soak through. That means that pollutants wash away with that storm water, straight into our streams and rivers. For us, that just doesn’t sit right. We love Portland for its lush landscape, dramatic downpours and thriving wildlife. To exist in harmony with these natural elements, we’ve planned carefully.
We have a rain garden that channels storm water from 5.5 acres of our roof and reduces the pollution in that water before it gets to the nearby Willamette River. Water flows through piping down through our building and cascades out of four scuppers into a series of nine shallow, narrow pools. The pools are separated by basalt weirs, which allow the water to plunge approximately 18” into the successive pool. The channel of pools is rock lined, and the edges are planted with native plants that will help to filter out sediment. The lower end of the rain garden forms a larger pool.
Storm water also enters this lower pool from a swale flowing from the north. This storm water runoff is from our loading dock. First treated with an oil-water separator, the water then flows 150 linear feet through a vegetated swale into another siphoned inlet, and then into the garden pool.
Water level in this lowest pool is controlled by the grate elevation of the final outlet. From this outlet, the storm water enters a 30 inch storm drain pipe, which is separated from the combined sewers. The pipe discharges the “treated” water into the Willamette River, just a few hundred feet to the west.
The Pacific Northwest is home to most of the last wild salmon in the country, according to the nonprofit Salmon-Safe. When our water is clean, native salmon can thrive. In 2007, OCC became the first convention center in the United States to earn Salmon-Safe certification. This recognition is the blue ribbon standard for urban and agricultural watershed protection.
This Portland-based nonprofit Salmon-Safe works with public and private landowners to promote reduced water use, onsite storm water treatment, and protection of water quality Properties like OCC are certified as Salmon-Safe for extensive efforts to halt runoff from entering streams and impacting imperiled salmon.
Our rain garden, as well as green cleaning choices and pest management practices, played a large part in our certification. Of course, we are also committed to strict water conservation, such as the use of low-flow fixtures and native, drought-tolerant plants.