Thursday, April 23, 2015

Seattle Pilot Project: Polluted Runoff Reduced

By Mark Edward Nero

The Port of Seattle and environmental groups said April 22 that results from a year-old pilot project have shown a reduced amount of polluted runoff reaching Puget Sound.

The research/demonstration project, called Moving Green Infrastructure, is part of growing efforts to reduce the amount of polluted runoff reaching Puget Sound, which is estimated to receive between 14 and 94 million pounds of toxic pollutants every year.

Two Dumpster-sized steel containers dubbed “Splash Boxxes” were installed at Terminal 91, with results gathered every four weeks. These boxes are a blend of rain garden and cistern, two practices referred to as low impact development, or LID.

Moving Green Infrastructure tests the water quality performance of two stormwater treatment techniques: a large “rain garden in a box” and a special soil mix with local, volcanic sands. Water quality from a roof in an industrial port area is being tested before and after going through the boxes to see how these two techniques perform.

After eight months of sampling, zinc levels are 1,000 times lower at the box output than the roof input after going through the soil and plants in the boxes, according to the project’s lead, Alessandra Zuin of environmental consulting company Gealogica LLC.

Information from the study is expected to help shed light on the potential for these bioretention planter boxes to improve water quality of polluted runoff in commercial/industrial areas and whether soil mixes used in rain gardens and bioswales could be improved.

The study is in partnership with King Conservation District, Sustainable Seattle, Gealogica LLC, and Splash Boxx LLC.

“We’re excited to see these dramatic results in the past year of this pilot program,” Port of Seattle Environmental and Planning Director Stephanie Jones Stebbins said. “Reducing levels of zinc from stormwater run-off is one of our toughest challenges.”