Town tackles stormwater
By ELISABETH MURRAY
Whidbey Examiner Staff
November 21, 2012 · Updated 10:12 AM
In the Coupeville area, oil from leaking cars, fertilizer from farms and flowerbeds, and other chemicals get flushed into Penn Cove - if left uncaptured and untreated. As water heads downhill it picks up contaminants along the way.
And this impacts the health of aquatic wildlife.
The Town of Coupeville plans to construct a 1.2 acre stormwater park to combat this problem. “Heritage Park” will serve as the final stage of treatment for a 90-acre residential watershed that drains to the cove.
The design plans for this park are 30 percent complete, said Greg Cane, town engineer. Design plans should be completed this winter.
The stormwater remediation park will serve as a model for other Puget Sound communities, said Cane. While similar projects have been constructed on the east coast of the U.S. and New Zealand, this will be a first for the Pacific Northwest.
During the design stage, researchers are testing the feasibility of using subsurface wetlands for stormwater treatment in this climate type, he said.
According to a report from town planner Larry Kwarsick, upland water already drains toward this field. It also already contains a sewer and storm drainage conveyance system, and a basic stormwater bioswale on site.
Once constructed, the artificially created subsurface wetlands will filter and remove pollutants from the stormwater before it is discharged into Penn Cove.
The cleaned water will also be used for summer irrigation to keep the wetland plants alive.
If feasible, water will also be reclaimed for farmland irrigation. The town is currently evaluating this possibility.
Heritage Park will also serve as usable public open space as a passive use park.
The Ebey’s Landing Historic Preservation Commission unanimously approved the project with two design considerations. Plants once used by local native Americans for basket weaving and an educational display must be included. Native plants must also be incorporated to soften or obscure the construction edges.
Like a staircase, the rectangular portion of the property will be broken into five tiered wetland cells.
If grant money is available, all five cells will be constructed in one phase. The other option is to break the project into two phases. The construction costs will not be known until the project is sent out for bid.
One stipulation of the land donation was that no structure higher than 4-feet be constructed. The only exception is that at one corner of the property near where a structure already exists single story construction can occur.
The property was donated by Chuck Poust, a $100,000 value to the town.
The Town of Coupeville was a sub-recipient of the matching grant from the state.
In addition to the property, the town is contributing $35,000 in staff time towards the project.