Rain Garden in a Box helps Treat Stormwater Runoff
Two port of Vancouver USA employees have recently invented an innovative stormwater treatment system in response to zinc pollution in stormwater from galvanized metal roofs and downspouts on the terminal.
Matt Graves, port environmental manager, and Mary Mattix, port environmental program manager call the new stormwater system the Grattix, but many others in the environmental world are calling it innovative, inexpensive, and effective.
Many water pollution problems are due to pollutants that are washed off land by storms. When small amounts from many pollution sources are combined, big problems may arise.
Zinc runoff can harm fish and wildlife, and the Port of Vancouver limits zinc discharge in stormwater to 117 parts per billion in accordance with their Washington State Department of Ecology Industrial General Stormwater Permit. This can be quite a challenge in an industrial setting.
Graves and Mattix decided to experiment with inexpensive materials in order to create an effective stormwater treatment system small enough to cater to 13 individual downspouts within the port Terminal. By combining their last names, they invented the Grattix.
The Grattix functions as a rain garden in a box, and is built using a food grade plastic 275 gallon drum. Inside, a layer of drain rock is added, followed by an under-drain piping system. This is filled in using a sand filter layer and amended soil consisting of sand and compost. The finishing touches include adding plantings and bark mulch.
The plantings used are rushes and sedges, which can dry out in the summer months and withstand ponding in the winter months.
During a pilot study of the Grattix from 2008 to 2011, the port environmental team collected inland and outland samples of stormwater and continuously found 90 to 95 percent zinc reduction. The only maintenance involved was periodically replacing the mulch layer, making the Grattix cheap, easy to make, and most importantly, effective in maintaining the health of the Columbia River and surrounding wildlife.
This early success has encouraged Graves, Mattix and the entire environmental team to create more Grattix treatment systems throughout the port, as well as spread the word to other industrial settings in need of innovative stormwater treatment options.
The Washington Stormwater Center, which created the Grattix video, helps local companies and individuals navigate complexities and challenges to realize the rewards of stormwater management through assistance, information resources, and training on stormwater management.