2 new rain gardens in PT filter runoff

Nicholas Johnson The Leader
Posted 7/26/16

Dwarf dogwood, evergreen huckleberry and red flowering currant are a few of the 20 plant species growing into their new homes since the mid-June installation of two rain gardens in Port …

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2 new rain gardens in PT filter runoff

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Dwarf dogwood, evergreen huckleberry and red flowering currant are a few of the 20 plant species growing into their new homes since the mid-June installation of two rain gardens in Port Townsend.

Dozens of volunteers helped the Jefferson County Marine Resources Committee install the rain gardens, planting some 870 plants at the corners of Washington and Walker streets and Clay and Taylor streets.

Volunteers included local school youths, a Washington Conservation Corps crew, Jefferson County Master Gardeners and interested community members who wanted to learn more about installing rain gardens.

All together, the gardens cost $7,600 for plants, supplies and committee members’ time. The money came from an annually recurring $70,000 grant for such projects given by the Northwest Straits Commission.

Bob Simmons, Olympic Region water resources specialist with the Washington State University Jefferson County Extension office, led the installation project. He said two rain gardens were installed last year on Garfield Street in Port Townsend, and two more are planned for next year.

“We chose these locations based on an assessment WSU did for the Jefferson County Marine Resources Committee, where we looked at the water-quality data in all the bays around Jefferson County to determine which stormwater outfalls were putting out the most contaminants,” Simmons said. “We then worked our way upstream from the outfalls and looked for the best opportunities where bio-retention (rain gardens) would help to reduce the amount of contaminants going to the outfall.”

The City of Port Townsend excavated the sites and provided bio-retention soils – a mix of 60 percent sand and 40 percent compost – which work to remove contaminants, such as heavy metals, bacteria, and pathogens from pet waste, petroleum products and sediment.

The WSU Jefferson County Extension office designed the gardens, recruited volunteers, put on an educational workshop and oversaw installation.

“This is a prime spot to clean [stormwater runoff], because after here, it goes into pipes that run into the bay,” Simmons said of the garden at Washington and Walker streets.

The gardens are designed to soak up runoff from light rainfall and overflow with runoff from heavier rainfall.

“Most of the contaminants run off the road when it first starts raining, which the rain gardens then soak right up,” he said. “As it continues to rain, the road runoff is cleaner, and if it overflows, it's not as bad as that initial flush, which the rain gardens absorb well.”

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