Stormwater swale project helps detect contaminants

Posted: Thursday, August 19, 2010

A small project by the Juneau Watershed Partnership could lead to bigger future results for water cleanliness.

Michael Penn / Juneau Empire
Michael Penn / Juneau Empire

A statewide study on water body contaminants by the Alaska Department of Conservation helped open the door for JWP to construct a demonstration model of a vegetated biofiltration stormwater swale at a local residence last month. Water authorities hope this model will help provide information on how to decrease nonpoint contaminants. Nonpoint contaminants are contaminants that cannot be traced back to a single source.

"Pollution can be a number of things," said DEC environmental program specialist Brock Tabor. He said nonpoint source pollution is a large problem in Alaska because things like sediments, chemicals, grease and other contaminants get mixed with rain and snow runoff and transported into water sources that way.

"Most runoff goes into water bodies, not treatment plants," he said. "The idea is to treat water before it gets to a river."

Tabor said nonpoint pollution is not only present in a majority of places but is trickier to contain since it gets into natural flows and cannot be regulated.

Shannon Seifert, project manager at JWP, said this is why a swale was built. She said it will be used to monitor and study sediment levels coming off the street the swale keeps out of the storm drain system.

The swale was placed at the Julep Street home of Erich Schaal, a civil engineer who also sits on the JWP board of directors. He said he volunteered in an effort to help update and promote the project.

Seifert said a swale at this location will filter nonpoint source contaminants entering the storm drain system and proceeding to the Mendenhall River.

Schaal said this swale, which resembles a small ditch with vegetation to act as a filter, is a typical drainage design for collecting stormwater and is commonly called an "area drain."

"A lot of people don't understand that they have an important purpose," Schaal said.

Schall said when JWP was looking for places to put a model swale, he jumped at the chance to "show other homeowners what they could do if they wanted to branch out in their responsibility efforts."

"It's a good example of 'if you want to see a biofiltration swale, come by here,'" he said.

Tabor said the swale is just one of many plans for pollutant studies. He said DEC's role was to provide the research that helps make projects like this possible.

He explained DEC's 2010 Integrated Water Quality Monitoring and Assessment Report categorized water bodies across Alaska and generated a point- and nonpoint-source pollutant budget. The report also labeled water cleanup plans.

He said this report helped provide scientific conformation of pollutants so JWP and the City and Borough of Juneau can pursue funding and put water cleanup plans into action.

Seifert said this swale was one of those plans, and while this is a small project, the information learned about nonpoint source containment can be used to generate solutions at other water sources that need it.

Tabor said Jordan Creek is a good example of one of these waters, as it has been considered impaired by nonpoint source pollution for awhile.

"The mix of sand and snow and parking lot residues create the potential for the perfect storm for the stream," he said. He said these mixes can impede salmon spawning and can also bury eggs.

Seifert said that since Jordan Creek now has a water cleanup plan, studies from the swale could be used to help the creek.

Schaal said the swale has already been doing its job, pointing out where sediments have collected before reaching the storm drain.

Tabor said that anyone who lives along water bodies can help filter contaminants on their own by allowing vegetation to grow along the edge to help generate a natural filter. He said this includes not mowing the edges or dumping grass clippings there.

• Contact Jonathan Grass at 523-2276 or

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