PORT ANGELES — A $1.12 million stormwater project in west Port Angeles to relieve flooding and improve stormwater runoff water quality is nearly complete.
The city has installed rain gardens at eight intersections on South H, K, L and M streets, as well as a new, larger drain pipe system to relieve flood problems on South H Street.
Rain gardens are designed to transfer surface stormwater to groundwater by providing planted “wells” for water to pool and soak into the ground, rather than entering the stormwater system, and to provide a natural filter for surface stormwater.
Water-loving plants are used in rain gardens and provide additional water removal and filtering.
Most of the work is complete at seven of the intersections of South H and South K streets at West Sixth and Seventh streets, at South L and West Fifth streets, and at South M and West Sixth streets, said Jonathan Boehme, city stormwater engineer.
On Wednesday, crews finished filling the rain gardens with filter and soil materials at West Fifth and L streets, which should be planted within the next week, Boehme said.
Completion originally was expected this month, but it was delayed by the unexpected discovery of a shallow sewage pipe and the delay of materials deliveries, he said.
The final rain garden is expected to be complete and planted before the Thanksgiving break next Thursday, Boehme said.
He expects the final touches to be finished in December.
All that remains is installation of pervious paving around the new rain gardens, which can allow up to 500 inches of water to filter through the pavement per hour, and some curb and backfill work, Boehme said.
The intersections have undergone a major change in appearance.
The corners of each intersection with rain gardens are “bumped out” into the parking lanes to provide space for the long, narrow gardens, leaving two 11-foot driving lanes for traffic, Kathryn Neal, city engineering manager, has said.
The project is expected to be a permanent solution for two city stormwater problems.
The narrowed road also is expected to serve as a secondary purpose of slowing traffic through the residential neighborhood.
Prior to 2009, the area around South H Street tended to flood during heavy rains because of a stormwater pipe that was too small, Neal said.
She said the city installed a temporary drain system in 2009, but water runoff flowing into Port Angeles Harbor was still contaminated with pollutants such as oil from the roads.
Most of the cost is funded by a $1 million grant from the state Department of Ecology.
Jordan Excavating of Port Angeles won the $1,125,308 bid in June. Construction began in July.
The new intersections feature sidewalks and Americans With Disabilities Act-compliant ramps, each connecting to existing walking areas on their respective streets, Neal said.
Each rain garden on H Street has an overflow drain attached to the new, larger stormwater pipe, while the K, L and M streets have no additional drainage, she said.
Killdeer Landscaping of Chimacum has lined each 3- to 4-foot-deep hole with filtration soils, leaving depressions for the water to gather.
The plantings include 44 tupelo trees and 10 species of plants selected for their ability to thrive in the conditions at the bottom of a rain garden.
Slough sedge, small-fruited bulrush, prairie fire and dagger-leaf rushes are planted in the deepest, soggiest portion of the rain gardens.
In wet but less soggy areas, flowering plants were selected: common camas, violets, yellow-eyed grass and magic carpet spiraea.
On the drier edges, kinnikinnick and wild coastal strawberries complete the gardens.
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Reporter Arwyn Rice can be reached at 360-452-2345, ext. 5070, or at arwyn.rice@peninsuladailynews.com.
