City of Bellingham, WA
By Tadd Giesbrecht, Brown & Caldwell
Background - The City of Bellingham has embarked on a project to fundamentally change the way their biosolids are managed. Through this defining shift, the City will move away from incineration, transforming the Post Point Treatment Plant to a resource recovery facility. The current incineration system is aging, expensive to repair, and incinerates – rather than recovers – reusable resources. Additionally, the current solids handling system only has limited capacity for long-term growth and is subject to increasingly stringent air quality regulations.
City Goals - To advance the City of Bellingham’s strong environmental ethic and commitment to greener solutions, in 2009 the City Council adopted the Legacies and Strategic Commitments, which highlight the City’s specific environmental goals. In addition, the City’s 2018 Climate Action Plan identifies the Resource Recovery project as the measure with the largest emissions reduction potential, making it essential to achieving the emission reduction goals. These goals directly influenced the development of biosolids planning options, as well as the selection of the preferred option. Through a triple bottom line (TBL) evaluation that accounted for environmental, social, financial, as well as technical considerations that were directly linked to the City’s Legacies and Strategic Commitments and the Climate Action Plan, the City selected a Class A anaerobic digestion as the preferred alternative.
A series of stakeholder outreach events were conducted to engage stakeholders to inform the project outcomes. Through this process, there was significant stakeholder support for moving away from incineration and upgrading to new facilities that incorporate resource recovery elements (e.g., biosolids and biogas). It was important to the stakeholders to develop a Class A program to maximize future flexibility and provide access to a local renewable soil amendment/fertilizer product.
Planning Decisions - Once the core stabilization technology (anaerobic digestion) was determined, the City needed to answer remaining questions around:
• How to use the biogas?
• How will Class A biosolids be processed?
• Where will the biosolids ultimately be used?
Through on-going stakeholder outreach and use of the TBL decision-making process, it was determined that injecting the biogas into a local gas utility pipeline would be superior from both an environmental and financial standpoint. With pipeline injection, the gas will be used to offset diesel vehicle fuels with cleaner natural gas, significantly reducing greenhouse gas emissions. Furthermore, it offers the benefit of available renewable gas financial credits (Renewal Identification Numbers [RINs] and Low Carbon Fuel Standard [LCFS] credits).
Given the decision to develop a Class A product that will be available for local use, the Class A digested “cake” solids from the digesters will need to be further processed (through composting or soil blending) to produce a soil-like product amenable for general public use. Because Post Point’s limited footprint wouldn’t allow for this additional processing step, an off-site project element is being planned.
Partnership Opportunities – Since the current incineration process results in ash disposal at a landfill, the City doesn’t have an established biosolids market. The City conducted initial market outreach to determine the current and potential biosolids product producers and marketers in the area, biosolids product attributes, and general interest in potentially partnering with the City in the hauling, off-site processing, marketing, and distribution of the Class A digested solids from Post Point. The outreach was also extended to national and regional biosolids producers to gauge interest in partnering. The City found considerable interest in potential partnerships and is advancing the outreach effort to further assess what these partnerships could entail.
Next Steps – The City is in the process of developing the Facility Plan to integrate the proposed digestion facility into Post Point and further develop the off-site product processing and marketing opportunities. As part of this effort, the consulting team of Brown and Caldwell/Carollo is also developing solutions to address the nutrient rich digestion recycle stream considering pending nitrogen limit regulations. In 2021, the City expects to move into the predesign and design phases of the project.