Collaborative, Trigger-Based Biosolids Masterplan for Seven-Facility Municipality in the Chesapeake Bay Watershed

The Anne Arundel County Department of Public Works (AACo) owns and operates seven (7) Water Reclamation Facilities (WRF): Annapolis Water Reclamation Facility (AWRF), Broadneck Water Reclamation Facility (BNWRF), Broadwater Water Reclamation Facility (BWWRF), Cox Creek Water Reclamation Facility (CCWRF), Maryland City Water Reclamation Facility (MCWRF), Patuxent Water Reclamation Facility (PWRF), and Piney Orchard Water Reclamation Facility (POWRF). The plants are distributed throughout Anne Arundel County, as shown in Figure 1, and range in size from approximately 1 million gallons per day (mgd) to 15 mgd. AACo maintains a contract with a single full-service provider (FSP) since the early 1990's who manages the entirety of the county's biosolids output. The FSP is responsible for operating the dewatering and Class B alkaline stabilization at AWRF, BNWRF, BWWRF, MCWRF, and PWRF; transporting liquid, unstabilized solids from POWRF to the PWRF; and processing a minimum of 25% of the total volume of unstabilized cake to meet Class A/EQ standards. The Class A/EQ requirement is being met by processing all the solids generated at CCWRF to meet Class A/EQ standards. Class B alkaline-stabilized biosolids are transported to a long-term storage lagoon or to permitted land application sites in Maryland, Virginia, or Pennsylvania. AACo maintains no on-site storage for dewatered cake, requiring off-site transport to storage, beneficial use, or disposal each day dewatering processes operate. To meet the Class A/EQ requirement, unstabilized solids are transported by the FSP to the FSP's Watershed Resource Center for processing via alkaline addition and pasteurization. In the face of current regulatory trends, diminishing end-use outlets, and emerging biosolids treatment technologies a new, holistic approach to managing the County's biosolids is being developed in collaboration between County staff and Hazen and Sawyer. The intent of this project is to develop a long-term biosolids management plan that will address these challenges, and was approached through four unique phases: initiate phase, comprehend phase, explore phase, and converge phase, as shown on Figure 2. 1 - Initiate phase: the project team investigated all of AACo facilities and operational data to understand the existing conditions of each WRF and their operational metrics. Then an end-use market study and regulatory assessment was conducted to build a comprehensive market assessment that would inform the next phase. 2 - Comprehend phase: a set of screening criteria and associated weights were developed, in a collaborative process with all project stakeholders, through a series of stakeholder engagement workshops. The weighted criteria would be subsequently utilized to rank and score biosolids management options against one another. 3 & Explore phase: An evaluation of regionalized and/or centralized location for the biosolids processing alternative. 4 & Converge phase: To maximize flexibility for the County, a trigger-based roadmap was developed that outlined the best possible biosolids management track should one of several no-go criteria be satisfied. To this end, the Masterplan was structured in such a way that a maximum of capital dedicated to a previous management track be shunted to the new, alternate track, that would circumvent (subvert?) the no-go trigger. Hazen and AACo worked and is working collaboratively through the project to develop a long-term solution for AACo. Some of the major challenges AACo faces include: - Large distances between WRFs, as well as locations of WRFs in relation to residential areas limiting the location for a Centralized/regional facility. - Potential long-term unsustainability of land application related to current and future regulatory trends. - Land-application Issues in MD/Chesapeake Bay. The world of options of potential biosolids management alternatives which will be evaluated as part of the project include: Gasification/ pyrolysis, Anaerobic digestion, advanced anaerobic digestion, anaerobic digestion coupled with thermal drying, third-party, composting, and thermal drying. In order to score and rank the alternatives against one another a set of criteria were developed which include: Technical, Economic, Environmental, and Social. A weight is assigned, as determined by AACo, to each criteria to allow for scoring and ranking. To address regionalization, a multi-facility tool has been developed. The tool is capable of tracking solids from various plants to singular or multiple outlets while also varying the type of treatment alternatives. The tool also tracks green house gas emissions and costs, providing a user-friendly dashboard of the findings. Additionally, a tool is being developed which will serve as a digital twin of the selected alternative. The digital twin will be capable of tracking energy and solids through a user-friendly dashboard. The project will be complete by the time of the presentation and will be presented by both AACo and Hazen. The presentation will provide a clear, concise path for master planning for utilities with multiple facilities.