As our communities grow and build for the future, we face the legacy of our past. In Seattle, stormwater and sewage were combined in the same systems when fewer people lived here and environmental sensibilities were different. Buildings were constructed with sturdy old-growth timber until that resource was depleted. Once-popular ingredients for paints and stains are now considered hazardous waste.
Project teams in the Wastewater Treatment Division (WTD) are transforming that legacy into a sustainable future, propelled by County initiatives to address climate change and support healthy communities.
The Georgetown Wet Weather Treatment Station will help to address overflows of untreated stormwater and sewage into the Duwamish River during heavy rains. King County designed the facility to treat up to 70 million gallons per day of excess flows until storms are over.
King County put construction in motion in 2017 with demolition of structures built decades ago for a variety of purposes. Underneath those structures, some contaminated soils needed to go. The project team and contractor made sure that where possible, “demolition” didn’t mean “waste”.
“King County’s Strategic Climate Action Plan has targets for zero waste of resources with economic value by 2030,” says Project Manager Will Sroufe.
“The Georgetown project is a great opportunity for us to find ways we can achieve those goals.”
Assistant Project Manager Matoya Darby explains how the team found ways to divert demolition materials from the landfills.
“We needed to tear down five buildings and remove concrete surfaces and underground equipment like pipes and storage tanks,” says Darby. “Many of the materials offered us opportunities to recycle.”
Nick Seeley, Project Manager for Titan Earthwork, described some of the reusable materials.
“There were old growth timbers that we salvaged from a warehouse,” Seeley said. “These are materials that just aren’t made anymore, and if we can safely recover them, they are a desirable item for reuse.”
Seeley also said that concrete can be crushed and reused. At the Georgetown site, concrete was hauled off site for recycling. Recycled concrete aggregate was brought in to the site to prepare surfaces for construction.
The Georgetown site posed some challenges because of the age of the facilities and past activities.
“The contractor was dealing with lead based paint, materials containing asbestos, and soils contaminated from underground tanks and past activities,” says Darby. “Items with hazardous materials just can’t be saved.”
Seeley says that safety is paramount during demolition. “We work hard to meet salvage goals, but not at the cost of safety to workers. If we can’t safely salvage materials, we dispose of them.”
Sroufe adds that the community is a critical consideration throughout construction.
“Reducing impacts to neighbors is an important part of sustainable building,” he emphasizes. “We needed good environmental controls in place during demolition, especially with some of the materials the contractor had to remove.”
Titan Earthwork worked diligently during a record dry summer to control dust and to keep runoff on site while removing contaminated soils and dealing with lead-based paint. Their efforts earned high praise from the County’s construction management team.
WTD’s Community Relations team prepared the community for construction, and continued to keep people up to date and address questions and concerns.
The collaborative effort between King County and Titan Earthwork to make demolition sustainable was a success.
“Our goal was 80 percent diversion of materials from the landfill,” says Darby. “We achieved at least 85 percent once it was done.”
Sroufe points out that sustainable building also has lasting benefits to WTD’s ratepayers. “We’re not just saving materials from going to waste now,” he says. “Sustainable building will help us lower our operations and maintenance costs once the Georgetown facility is online.”
Projects like the Georgetown Wet Weather Treatment Station show how King County can turn that historic legacy into a healthy future for our communities and our environment.