Anacortes begins multi‑year review of wastewater biosolids options as incinerator ages

The Anacortes City Council on March 23 heard the first public briefing in a multi‑year process to decide how the city will handle biosolids after its 34‑year‑old incinerator approaches the end of its service life.

Brian Walker, the city’s wastewater manager, and Greg Makos of Brown & Caldwell told the council the study will identify up to six end‑to‑end alternatives — from upgraded incineration to digestion and beneficial reuse — and score them on environmental, social, financial and technical criteria. Makos said the firm used a conservative approach to estimate how much the city can invest in the current incinerator before triggering stricter air‑permitting requirements under the federal/State 'Quad L' rule.

"We estimate you have about another $4,600,000 that you can spend on the incinerator before triggering the 50% threshold," Makos said, stressing the figure is a planning‑level, conservative estimate and subject to further review.

The presentation framed a Quad L upgrade to the incinerator — a comprehensive air‑pollution control replacement — as a planning‑level cost in the range of $8.4 million (planning‑level ranges are intentionally wide, Makos said). The consultant emphasized the difference between campaign‑level planning estimates and a final design budget, noting planning‑level numbers can vary by minus 50% to plus 100%.

Councilmembers pressed the team on site constraints, lead times and how mandatory goals might screen technologies. Makos said the city’s staff had set several mandatory goals — the technology should fit on site (or a feasible city‑owned off‑site parcel), be adaptable to regulatory changes (including PFAS), not rely on proprietary consumables, and produce a product that can reach multiple outlets. "Technology needs to produce a product that can be sent to multiple outlets," he said.

Makos also described the team’s decision‑science approach: staff and council will rank evaluation criteria in a multi‑criteria decision analysis (MCDA) workshop later this year that will assign weights to items such as cost, greenhouse‑gas emissions and permit compliance. Staff will then use the SWEET (solids, water and energy evaluation tool) model to produce comparative inputs for each alternative.

The consultant noted there may be opportunities for beneficial reuse in the region — for example, local soil‑blending businesses could accept a Class A biosolids product — but said significant outreach and education would be required to develop stable markets.

The council and staff agreed to publish project materials and the survey on a project web page to ensure public transparency. Makos said a preferred alternative is expected later in the process once council and public input have been collected and the MCDA is complete.

Next steps: an online survey for council and public input, followed by an MCDA workshop in the fall and preliminary engineering for the council’s preferred alternative.