It’s a fact of life that every municipality has to figure out a system for treating and disposing of human waste. For decades, the City of Edmonds has been separating the solid material from the liquids, flltering and pressing the material, and then incinerating it at the city’s wastewater treatment plant at 2nd Avenue and Dayton Street.
However, the city’s 30-year-old sludge incinerator “is really showing its age,” Public Works Director Phil Williams told the Edmonds City Council’s Parks and Public Works Committee Tuesday night. It’s becoming more difficult to find spare parts for aging components and it’s estimated the incinerator has five to seven years of useful life remaining. In addition, stringent and expensive new regulatory requirements for sludge incineration are virtually impossible to meet, Williams said.
After studying a range of options, Williams said, city staff have landed on what they believe is “the best for Edmonds” — a two-step process that involves sludge drying and pyrolysis.
The second step — pyrolysis — is the chemical decomposition of organic materials at high heat with little to no oxygen. This creates both a dried product and a “biochar,” which Williams described as sterile and having the appearance of charcoal. The biochar byproduct can be used in city parks or sold as a soil conditioner or amendment, he said.
An equally important benefit of the process, Williams said, is that it is energy efficient and produces a reusable product, which will help the city meet its “zero waste” goals. “It’s a wonderful thing from an environmental perspective,” Williams said. “It dramatically reduces your carbon footprint.”
Williams also said the technology fits into the relatively small footprint of the city’s existing wastewater plant,
He cautioned that all of the alternatives studied — including this option — “are very expensive,” and estimated that the total cost of pyrolysis system would be in the range of $15 million.
The next step would be council approval of a $236,000 contract with Ameresco to conduct an engineering analysis and preliminary design for a system to replace the sludge incinerator, including a closer look at the pyrolysis option.
Given the significant cost of the project and other councilmembers’ interest in zero waste efforts, Parks and Public Works Committee members agreed that Williams should make a presentation to the full council prior to approving the contract.
This item was one of two that the committee referred to the full council for a future presentation. The second was a review of a professional services agreement for Civic Field design services, which staff is recommending be awarded to Walker Macy. That’s the same firm that worked with the community to develop the Preferred Master Plan for Civic Field.
In addition, the committee also referred the following items for placement on the next council consent agenda for approval:
– A contract with Dungeness Construction to complete the Seaview Park Infiltration Facility.
– Acceptance of final construction costs for the Frances Anderson Center Bandshell Replacement Project.
– Approval of a supplemental agreement with Murraysmith for the 2019 Sewerline Replacement.
– Approval to close out the Civic Stadium project demolition.
– Final acceptance of the 228th Street Southwest Corridor Improvements Project.
– Approval of city special event contracts, including the Classic Car Show, Fourth of July, Market and Taste.
– Approval of a resolution to submit five grants to the Washington State Recreation Conservation Office for two parks projects — Civic Field and the Edmonds Waterfront Walkway.
— By Teresa Wippel