ASCE Environmental & Water Resources (EWRI) January Committee Meeting: Navigating Nutrient Requirements for Puget Sound
Thursday, January 16, 2020 – 12:00pm to 1:00pm
Navigating Nutrient Requirements for Puget Sound
David L. Clark, PE, WEF Fellow
Wastewater Market Sector Director, HDR
Bryce Figdore, PhD, PE
Senior Wastewater Process Engineer, HDR
Wastewater utilities that discharge to Puget Sound face new caps on nutrient discharges that are intertwined with complex water quality issues ranging from compliance with Washington’s strict dissolved oxygen standards and new criteria for toxics, to broader implications for food chain impacts on endangered Chinook Salmon and Orcas. Nutrient management requirements compete for limited funding resources with a multiplicity of other challenges that wastewater managers must address. These issues include continuing provision of adequate capacity, wet weather compliance, asset management demands, resiliency, etc. Changes in wastewater characteristics, climate, demographics, and societal priorities all contribute to a cauldron of challenges to form the most complex operating environment to confront utilities since the inception of the Clean Water Act.
Washington Ecology has published a Bounding Scenario water quality modeling report as part of the “Puget Sound Nutrient Source Reduction Project” that includes seasonal biological nitrogen removal at all municipal wastewater facilities with an effluent concentration of Dissolved Inorganic Nitrogen (DIN) of 8 mg/L and CBOD of 8 mg/L. Meanwhile, Northwest Environmental Advocates (NWEA) petitioned Ecology to adopt a rule establishing technology-based effluent limits for the discharge of nutrients and toxics from municipal wastewater treatment facilities that discharge to Puget Sound to include effluent limits for total nitrogen of 3.0 mg/L and phosphorus of 0.1 mg/L, or lower. In rejecting the NWEA petition, Ecology has committed to cap nutrient discharges and continue to pursue modeling to establish water quality based effluent limits.
This presentation will focus on strategies for easing the transition to nutrient removal through approaches that combine innovative regulatory frameworks with treatment technologies that address multiple utility challenges. Finding the optimal intersection between compliance requirements and treatment technology is the key to successfully navigating all of the demands for utility management on Puget Sound.
1800 112th Ave. NE
Bellevue, WA 98004
Cover image: Seattle Design Pup.