Waterworks Gardens
Seven years after it opened to public and industry accolades, Waterworks Gardens in south King County, WA, still attracts international attention for the way it turned stormwater treatment into a beautiful thing.
A common goal at water treatment plants has always been to avoid being seen, heard, and most especially smelled, relates Richard Butler, process control supervisor for King County’s South Treatment Plant in Renton. So when an artist hired to “dress up” an addition to the plant suggested replacing stormwater ponds with a pond-filled public park, her idea was not even close to what the planners had in mind. The artist, Lorna Jordan, was quite persuasive, however, and now those associated with the project speak proudly of the successful collaboration.
“It turned out really well. Some of us were surprised that it was accepted so quickly and given so much praise,” Butler says. “There are a lot of art projects involved in so many government projects. They tend not to get this kind of praise on a communitywide basis.”
What really amazes Butler and others is how much the park is used every day; they also have been astounded by some unusual requests from the public. “We’ve had calls from people interested in having weddings in the Grotto!” which is the stonework focal point of the garden. A wedding at a water treatment plant? Butler still laughs at the idea.
Treating Stormwater Runoff
Waterworks Gardens is an 8-ac. facility that naturally filters stormwater collected from more than 40 ac. of impervious surface at the South Treatment Plant through the use of 11 ponds and enhanced existing wetlands. The ponds are connected by a series of pipes that allow for up to a 4.5-cfs flow rate as delivered by the stormwater pump station, which adds up to about 2.2 million gal. a day. The ponds are fed by both a variable speed pump and a constant speed pump, which can serve as a backup. Valves at the plant can be set to divert flow to the wastewater treatment plant rather than to the wetponds to allow for inspection, draining, and servicing. Before the waterworks were built, all of the stormwater runoff from the plant went into the wastewater treatment system.
Waterworks Gardens was built as part of the third phase of the South Treatment Plant. The plant opened in 1965 and now serves a population of more than 600,000 people in south and east King County.
The ponds are designed to hold a total of 642,327 gal., including room for 15.9% sediment storage. Sediment is removed from the ponds, however, when it exceeds 10% of the total volume. Some of the ponds have emergency drains to catch overflow water. The paths around the ponds also were built in a way to create a flood drainage system. The park is designed to handle a peak 24-hour, two-year storm.
All of the wetponds are constructed with a layer of indicator rock on the final, exposed bottom surface. This protects the underlying impermeable layer of polyvinyl chloride sheeting.
A recirculation pump draws water from the last wetpond and returns it to the first pond, resulting in a continuously flowing loop of about 250 gal./min. cascading through all the wetponds. This helps avoid stagnation, prevent ice formation, enhance pollutant removal, distribute makeup water, and provide a water supply for the water features. The process also seems to keep the mosquito population under control.
Before releasing the water into neighboring Springbrook Creek, King County concerns itself with ridding the water of sediment, oil, and grease from vehicles on the plant roadways; suspended metals; and fecal coliform from the bird population in the wetlands. The principal sources of silt-laden runoff on the site are construction vehicles associated with onsite earthwork excavation and building.
Combining Budgets for Stormwater and Art
Originally planned as three ponds surrounded by a fence and some large trees to keep the area hidden from public view, Waterworks Gardens was transformed by creative thinking and budgeting. In 1973, King County established the One Percent for Art Program, which mandates that 1% of the budget from public construction projects must be used to purchase or create public art. The program often supplies money to improve the appearance of public projects, but environmental artist Jordan had no interest in simply plopping down some public art. She was a woman with a mission: to help people reconnect with the systems that sustain them.
Jordan felt the best way to accomplish her goal of making the water treatment plant more accessible to the public would be to integrate the art with the infrastructure, and because she was hired by an art committee and not by the engineers and architects, she won converts from the beginning. “The artist can be a little bit of a free electron and try to push the envelope,” Jordan says. Those involved in the project south of Seattle agree that is a good description of her contribution to Waterworks Gardens.
The budget for a $6.5 million addition to the water treatment plant included $650,000 for art. Thanks in part to Jordan’s creative leadership, the county decided to add the art budget to the $300,000 the county had set aside for stormwater detention ponds, along with about another quarter million dollars for wetland restoration. The three budgets were combined creatively to pay for Waterworks Gardens, giving the team of artists, landscape architects, engineers, and government employees a total of $1.1 million.
Jordan believes this kind of creative planning across agencies and disciplines can be replicated in other communities, even if they do not have a specific program for funding of public arts. Many of the jobs she has worked on since Waterworks Gardens involved quite a lot of collaboration and cross-agency work. She has even been hired by several entities, including Broward County, FL, to help figure out how to make these kinds of collaborations possible.
The design and planning process for Waterworks Gardens went on for years, and by the time the park opened in June 1996, nearly everyone involved had a great feeling about the creative process and the results. Jones & Jones, Architects and Landscape Architects Ltd. of Seattle, WA, and consulting engineer Brown and Caldwell of Walnut Creek, CA, assisted with the design. The project was constructed by Fuji Industries Inc. of Milton, WA, between 1995 and 1996. Waterworks Gardens has received several awards, including the 1996 Outstanding Local Civil Engineering Award presented by the American Society of Civil Engineers, Seattle Section, and the 1998 Place Design Award presented by Places magazine.
Jordan designed the site to symbolize a large flowering plant. The water is pumped to the introductory area known as the Knoll, which represents the root of the plant. The first group of ponds is shaped like leaves and leads to the Grotto, which features a mosaic resembling a sprouting seedpod. The ponds after the Grotto are circular to represent the fruit of the plant, and the wetlands include islands and channels to imply the flower of the plant. All of the ponds are surrounded by primarily native vegetation and have attracted a variety of wildlife. A path called the Water Walk, which travels from metal grating to asphalt to gravel, weaves through the ponds and wetlands to join trails from the adjacent cities of Renton and Tukwila.
Water-Quality Results
Butler says Waterworks Gardens has been moderately successful in meeting its water treatment goals. “We’re getting suspended solids removal but not as much as you think–[our removal is] in the 30% to 50% range,” he says. The fecal coliform tests are increasing but not as high as county officials anticipated. “We expected it would probably be higher because there are so many birds there, especially geese,” Butler adds. The county does not test for oil and grease, so Butler cannot say how well they are doing in this area, but he does say they have never seen anything to suggest they have a problem.
The gardens were designed to comply with the state and county versions of the National Pollutant Discharge Elimination System Phase II rules. New stormwater regulations that went into effect in 2003 will require the county to take more samples, but Butler does not believe the increased sampling will lead to any changes at Waterworks Gardens.
Minor Adjustments: Muskrats and Cattails
Most of the changes that have been instituted can be traced directly to either design flaws or unexpected impacts of nature on the facility. The best example is a potential problem the builders saw before they finished the gardens but did not have the money to mitigate. Because Waterworks Gardens is built on a hill, it requires the county to pump the water uphill all day, every day of the year. This puts a lot of wear and tear on the one recirculation pump installed in the gardens, and when wear and tear led to pump failure during the summer of 2003, the county was forced to shut down the system, drain the ponds, and replace the pump. A backup pump installed during construction would have been a less expensive solution, says Mark Sakagami, senior gardener at the South Treatment Plant, but there wasn’t enough money for this item in the original budget.
Waterworks Gardens is built on a hill because the landscape preexisted the project and aided in its aesthetic plan, but given a chance to do the project over again, Sakagami says he would avoid the hassle: Building on a hill requires the use of 24-hour pumps, initially to get water up the hill from the plant and then back up the hill with the recirculation pump to maintain a continuous flow. The other changes he would make are mostly minor and not as expensive. The concrete retaining wall around the water feature at the Knoll should have been longer, he says. Having a longer retaining wall would have prevented some repairs that now need to be made to the structure because erosion around the wall has created a “hole” in the pond.
Sakagami also would have done more to prevent cattails from growing uninvited throughout the wetlands. If the wetlands ponds had been dug deeper and steeper, the cattails would not have caught on so quickly and efficiently, Sakagami has learned. And because the wetlands do not have indicator rock, digging out the plants in the area is not an option. The cattails have consumed so much of the wetlands that the area is now prone to flooding. The solution Sakagami’s team has devised is raising the gravel path by 1 ft. in this part of Waterworks Gardens instead of “lowering” the water features by excavating.
Another issue involves the burrowing animals, such as muskrats, that have moved into the gardens as not entirely welcome guests. The county has been forced to trap and relocate some of them, but Sakagami says the developers could have done more to discourage muskrats from moving in. For example, the indicator rock on the bottom of the ponds goes up only to water level. If it had been installed 10–12 in. above water level, the muskrats might have looked for a different place to dig because they like to build their homes at the water’s edge.
Sakagami, who spends more time at Waterworks Gardens than anyone else interviewed for this article, says the project is 100% successful in at least one area: public approval. “When I tell people we spent $1.1 million on this project, they say it was worth it,” he relates, adding that public use of the park is heaviest between 10 a.m. and 3 p.m. on weekdays, when workers at neighboring office buildings and plants stop by for a walk.
For his first 10 years with King County, Sakagami was the only gardener working in the wastewater area. Now he also serves as an informal tour guide for visitors from around the world who want advice on building their own stormwater gardens, and he has helped during the design stage of several other stations in the county. For the next big project, a water treatment facility called Brightwater will be built on the northern edge of King County. Sakagami says Brightwater will include a stormwater park inspired by Waterworks Gardens. The planners of that facility have visited the south King County plant to gather information and inspiration.
Butler notes that the public acceptance of Waterworks Gardens and the way the project has helped people appreciate the work done at water treatment plants have actually helped move the Brightwater project along.
Jordan says making these projects more beautiful and accessible helps advance the public conversation about how people are connected to the infrastructure of their communities. “A lot of infrastructure projects are functioning, but people don’t have any connection to them. People need to make contact and understand the mysteries of water,” she says. She believes there is room in the world for more attractive public spaces: “The world isn’t as marvelous as it can be.”