Roadside rain garden project earns local civil engineering honors

When heavy rains pound the pavement in West Seattle’s Sunrise Heights and Westwood neighborhoods, polluted runoff takes a detour from Puget Sound.

That’s thanks in part to the Barton Roadside Rain Garden project, a network of 91 rain gardens built to keep stormwater out of the sewer system, where it used to overflow at the Barton Pump Station near the Fauntleroy ferry dock.

The Seattle chapter of the American Society of Civil Engineers recently honored King County’s Barton Roadside Rain Garden project with a 2017 Local Outstanding Civil Engineering Achievement award in the water resources category.C1After2Though the term “infrastructure” might spark images of concrete and steel, today’s engineers increasingly see nature as another viable building tool for shaping 21st century cities. WTD is among many clean-water utilities nationwide exploring ways to include green infrastructure in long-term plans to reduce pollution and protect water quality.

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The rain garden project during construction

Getting the site right
Our planners and engineers were pretty excited when studies showed the area to be a good candidate for a green infrastructure approach to controlling combined sewer overflows. Also known as “CSOs”, these overflows of stormwater mixed with small amounts of sewage sometimes still happen in waterbodies around Seattle’s oldest neighborhoods.

To make sure the roadside rain gardens would work properly at controlling CSOs, our technical teams looked carefully at the neighborhoods’ topography, soil conditions, and location within our sewer service area.

The Barton roadside rain gardens were installed in the planter strips between the curb and sidewalk over a span of 15 neighborhood blocks. They work by filtering runoff through a system of compost-enriched soil and specially-selected plants to a drain pipe, which takes the water to a deep well where the runoff is slowly absorbed underground.

Keeping the “plants” running
Like traditional gray infrastructure, the roadside rain gardens are inspected and maintained to ensure they function as designed and comply with regulatory requirements.IMG_3571

People in the neighborhoods where our roadside rain gardens are located are likely to see work crews at least monthly, with more frequent visits before and after large storms, or during the summer growing season. During a rain garden maintenance visit, workers typically remove weeds and debris, clear gutters, monitor the pipes and wells and of course, make sure the plants are thriving.

Workers also carefully monitor for overflows in Puget Sound near the Fauntleroy ferry dock.

And just like any other facility we operate, the rain gardens even have signage so people can call to report problems. The Barton Roadside Rain Garden project was completed in 2015, and performed well during the 2016-17 rainy season, which was one of the wettest winters in Seattle’s history, with a whopping four feet of rain.

The design and engineering were led by the Seattle-based MIG/SvR Design Company, and Goodfellow Bros. Inc. managed the rain garden construction and installation.

More information about the Barton roadside rain gardens and their role in controlling combined sewer overflows is available online.

 

 

 

 

 

 

 

 

 

 

 

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