The following is an excerpt from City Parks, Clean Water, a report by The Trust for Public Land’s Center for City Park Excellence that examines the role of urban parks in managing stormwater. This is the fifth installment in a series of 19 posts.
After the Seattle suburb of Shoreline passed a parks and open space levy in 2006, the city sought renovation projects that could meet multiple city goals. One opportunity arose at 9-acre Cromwell Park, a flat field on the site of a former school in a neighborhood with frequent floods. The surrounding Meridian Park community had already been targeted for a major stormwater upgrade by the city’s public works department.
“It was filled with a lot of dead grass and not much else,” laughed Kirk Peterson, who oversaw the project for the parks and recreation department. The two agencies partnered on Cromwell Park’s redesign, radically restoring the site’s natural topography and redirecting runoff to a wetland for treatment. They built new inlets from adjacent residential streets and a nearby county building, where most of the runoff percolates into the ground. (In a deluge an overflow outlet releases excess water to the sewer system.) The 1.33-acre wetland can hold an acre-foot of water (almost 435,000 gallons), enough to eliminate the neighborhood flooding problem.
Most noticeable to residents are the recreational improvements. The renovation added a new playground, a full-size basketball court, and a new baseball field. Walking trails encircle the wetland, even crossing it on a bridge. Neighbors were adamant that the wetlands not be fenced off, Peterson noted, although the city eventually had to install safety cables by a particularly steep-sided section. One of the best investments, Peterson added, was the selection of diverse, native wetland vegetation that makes the park look good even in dry spells.
Changes in the park sacrificed some recreational space, but Peterson said the wetlands have become one of its most popular features. “In the design process, neighbors were skeptical. They were worried about mosquitoes and bad smells. But now people love the space. There is often interesting wildlife, and people are fascinated to see the basins fill up with water after a rainstorm.”
Design and construction, which lasted from 2007 to 2010, cost $1.6 million, with about
two-thirds coming from the park bond and one-third from the Surface Water Utility Fund. The two agencies share maintenance responsibilities, with the park costing about $60,000 a year and the stormwater features about $11,000.