Puget Sound wastewater treatment plants to tackle nutrient pollution with new permit

Art fountain at the Edmonds wastewater treatment plant

To stop the flow of nitrogen pollution and improve the health of Puget Sound, the Washington State Department of Ecology is requiring – starting January 1 – that wastewater treatment plants – including those of ‘Edmonds and Lynnwood – monitor releases, optimize operations and plan infrastructure. investments.

Excess nitrogen is the main pollutant causing low and unhealthy oxygen levels in Puget Strait, and a cascade of problems for fish and other marine life, according to the Department of Ecology. New Puget Sound General Nutrient Permit places 58 wastewater treatment plants on a multi-year path to control and significantly reduce nitrogen emissions. Most of these facilities currently do not have nutrient control technologies. This means that the nitrogen in human waste flows from homes and businesses, through facilities, directly into Puget Sound.

While Edmonds and Lynnwood have their own treatment plants, Mountlake Terrace sends its wastewater to the Town of Edmonds for treatment. Brier’s wastewater, on the other hand, flows to the West Point treatment plant in King County.

The permit operates in five-year cycles, with the Department of Ecology updating and refining the requirements at each cycle based on lessons learned from permit implementation and public feedback. Due to the large difference in the amount of nitrogen released from the facilities, the requirements are divided into three categories: dominant (seven facilities), moderate (20 facilities) and small (31 facilities).

Town of Lynnwood Wastewater Treatment Plant.

The seven dominant facilities are responsible for over 80% of the excess nitrogen entering Puget Sound. Mid-sized establishments represent 19% and small establishments contribute less than 1%. Ecology developed these categories and related requirements, based on feedback from an advisory committee and two rounds of public comments held earlier this year. (Edmonds and Lynnwood are considered mid-sized facilities.)

The first five years of the permit (2022-2026) focus on preventing the worsening nutrient problem, while the facilities identify long-term technology upgrades and other investments to better control nutrients. . The Ministry of Ecology requires facilities for:

  • Monitor wastewater for nutrient reductions and collect data to support potential water quality exchanges between facilities.
  • Optimize current treatment processes to remove as much nitrogen as possible.
  • Plan for future facility upgrades to control nutrients.

Optimizing performance in the first five years of the license is the first step in reducing nutrients entering Puget Sound from these facilities. Ecology predicts that many plants can reduce nitrogen by 5-7% or more by optimizing existing treatment processes during this time. Optimization alone will keep thousands of pounds of nitrogen a year out of Puget Sound. Facilities are eligible for Ecology scholarships to help cover optimization and planning costs.

The seven installations in the dominant category have additional requirements. If they cannot maintain or reduce their nitrogen levels through optimization, they must find ways to reduce their nitrogen by 10% in the short term while planning long term investments.

Communities and their facilities have a range of options to reduce the amount of nitrogen they release into Puget Sound. As part of the required planning, the Ecology Department has said it expects facilities to consider what is affordable for their community. Ecology predicts that nutrient control technologies will be online at most facilities over the next 15 to 20 years. This reflects the time and financial resources it takes to plan and build these major infrastructure improvements.

The new permit takes effect in 30 days, effective January 1, 2022. To view the permit and other related documents, visit ecologie.wa.gov/NutrientPermit.

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