Stormwater Solutions

Research Courtesy of Team Echo: Owen Chapman, Casey Currey-Wilson, Anne Gilleland, Eve Lowenstein, Gene Yamamoto

Team Echo meeting with the maintenance staff at Catlin Gabel School

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The Stormwater Problem
Solutions
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The Adventures of Stormwaterman

Part 1
The Stormwater Problem and What Our Community (Portland, Oregon) is Doing About It:

Climate change affects Portland, Oregon by giving us drier summers and wetter winters, which leads to more concentrated rainfall and increases stormwater problems. Annual rainfall in the past 30 years has remained constant, but rainfall in the winter has increased. More rainfall during a shorter time floods stormwater systems, leaks sewage, erodes streambeds, and pollutes streams because of pollutants in stormwater runoff. Increased rainfall will increase pressure on transport routes and other infrastructure. Structures will have to be stronger to resist collapse in extreme weather conditions.

Portland is doing several things about stormwater already. The Big Pipe Project on the East Side of Portland started in February of 2003 and is scheduled to end in December 2011. The cost is estimated to be around 1.4 billion dollars and will reduce 94% of combined sewage overflows or CSOs. The tunnel is 22 ft wide and 6 miles long. There are shafts in construction that will connect the existing overflow pipes to the Big Pipe and grant access to the tunnel. These shafts are about 49-60 feet in diameter and 110-165 feet deep.

Bioswales are a very popular option in our community. A bioswale is a landscape element designed to remove silt and pollution from the surface runoff water. They also serve to slow water down.

Porous Concrete was first used 2 years ago in the Portland area. It is not often used in private developments up to this point. Porous concrete is almost as durable as regular concrete but not as strong and can last from 50-75 years. The cost is around twice as much as regular concrete, but it doesn't need any underground piping for runoff, which makes up for the cost. It is more expensive because the material is screened for fine particles that would fill the space where the storm water travels.
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A chart showing increased winter rainfall in Portland

Part 2
Our Ideas for Stormwater Solutions:

Our solution is to increase the pervious surface in watersheds, as any watershed that is more than 10% impervious is likely to be unhealthy due to pollution from stormwater runoff that is not filtered by the groundwater. One way to do this is to use porous concrete. Porous concrete is not strong enough to handle very heavy traffic, but there are many uses for it other than for roads. It can eliminate runoff when used for parking spaces, driveways, walking paths, sidewalks, the layer under a jogging track, and many other uses. It can help preserve play areas by allowing them to drain rather than create puddles. Pervious concrete is expensive, but it pays itself off with the savings of not having to install storm drains and pipes.

Another solution is to install bioswales, especially in the headwaters of creeks. Bioswales are patches of water-absorbing plants and sand in areas that see lots of runoff. The most effective bioswales send the water in a less direct course, because the longer the bioswale, the more water it absorbs. Bioswales are an especially good idea in an area where runoff often flows toward a storm drain.
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