Industrial Raingardens

Spring Street Demonstration Project

Boundary Water Inc was pleased to contribute surveying, civil design & construction services to help build the first urban rain garden in the Town of Friday Harbor. The monitored demonstration project uses selected plants and soils to clean runoff from approximately 10,800 sf of paved area in the town. The DOE funded project was administered by the San Juan County Marine Resources Committee

Since most of the pollution generated in urban environments is collected on paved areas, the project will measure the effectiveness of treatment at the source.

The project was challenging and lots of fun. A local man actually broke construction barriers and jumped in the open excavation. See article in the Island Guardian (

To see the San Juan County flyer for more information about this project follow the following link: raingarden.pdf

San Juan County Marine Resources Committee: Saving our Bay

A rain garden can help keep toxics out of our water
The Problem: Toxics in our road runoff include gasoline, lubricants, detergents, metals (zinc, copper), and antifreeze, and continue to pollute our waters on a daily basis. As gasoline and other pollutants drip from our cars, they are picked up and carried by rain runoff down our streets into Friday Harbor, where they can harm eelgrass, fish and other wildlife, and disrupt marine food webs. Some toxics dissolve in rainwater. Other toxic chemicals stick to silt particles washed down the street by moving water. Driving wears down brakes, tires, and road paving, leaving fine toxic dust that wash down storm drains. Polycyclic Aromatic Hydrocarbons or PAHs are some of the most serious toxic contributions of cars and roads to rain runoff. PAHs naturally occur in petroleum and most petroleum products, including motor oil, tars and asphalt. Burning gasoline and oil in an engine creates more PAHs, which cause cancer in humans and animals.

The Solution: The Town of Friday Harbor, the San Juan County Marine Resources Committee and the Washington Department of Ecology have joined together on a project to determine how well rain gardens can treat runoff. Work has begun on an experimental rain garden at “Herb’s Corner” on Spring Street. Storm water will be filtered through a thick layer of soil, giving the plants time to take up and sequester pollutants. Beneficial bacteria and fungi in the living soil may break down some pollutants and make them harmless. As plants continue to grow over the next few years, the rain garden should be more and more effective. If successful, this project may be applied on a larger scale to significantly decrease pollutant concentrations in Friday Harbor.

Effectiveness: Many factors contribute to the effectiveness of rain gardens, beginning with the size of the garden, and the depth and composition of the soil. This will affect the volume of water that can be processed per minute, and how long water is in contact with roots, fungi and bacteria. Finding plant species that have the ability to take up and sequester pollutants will affect the rain garden’s ability to reduce dissolved toxics. Bacteria and fungi are vital to actually breaking down pollutants, so a rain garden is much more than what we can see growing—and it may take months or years for a rain garden to develop a healthy and diverse community of soil organisms. At the same time, the effectiveness of the garden will decrease if it becomes saturated with contaminated solids: its plants, fungi or bacteria may die. If a rain garden filters out contaminated silt and dust but does not break down the contaminants, the rain garden itself will become toxic waste and will need to be disposed of and replaced, like a home water filter.

Measuring Success: The partners have asked a local nonprofit laboratory, Kwiáht, to determine how well the experimental rain garden works during its first year of operation. Kwiáht scientists will wait until the first fall rains to sample road runoff where it goes into the garden, and where it comes out (that is, influent and effluent water). Each sample will be tested for the concentration of specific contaminants (PAHs, copper, zinc, and surfactants) as well as the total amount of oil, total dissolved solids, and total suspending solids (silt and dust). Two kinds of methods will be used: colorimetry and ELISA immunoassay. In colorimetry, a spectrophotometer measures the absorbance of different wavelengths of visible light in a solution. Some chemical compounds—such as Antiaminopyrine in the presence of copper—have distinctive absorbance peaks. ELISA uses an enzyme linked to an antibody to detect groups of closely related chemical compounds in a sample. ELISA is extremely sensitive. For example it can detect PAHs at concentrations as low as one part per billion (0.00000001 percent). Rain garden soil will also be tested to see whether a diverse and healthy community of fungi and bacteria is forming!

How to find out more: Kwiáht is on Facebook! Testing results will be posted on our Facebook page and on by December 31. Or contact us directly with any questions or comments you may have:
Project Manager – Brian Rader (San Juan County), 360 370-7581
Russel Barsh (Kwiáht laboratory supervisor),
Sarah Clark (Friday Harbor High School intern),

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