Fortune Favors the Prepared: Loudoun Water’s Master Planning Process for an Evolving Future
- Janice Carroll, Phill Yi, Wendell Khunjar, Ron Taylor, Paul Pitt - Hazen and Sawyer
- Sarah Lothman, Mike Latham, Michael R. Rumke, Roddy Mowe - Loudoun Water
The purpose of this presentation is to discuss an approach to strategic planning that embraces the realities of regulatory and technological uncertainty when making decisions today for the water and wastewater operations of tomorrow. The foundation of the approach is the designation of a trigger and response strategy, as well as graphical means of communication, which enable utilities to prepare for multiple scenarios of the future and facilitate a more efficient organization.
The Broad Run Water Reclamation Facility (BRWRF) master planning process is presented to demonstrate this trigger-based approach. The BRWRF Master Plan included the development of trigger-based strategies for liquids treatment, solids management, reclaimed water, nutrient recovery, carbon recovery, metals recovery, and energy management. These trigger-based strategies, such as the Reclaimed Water Strategy (Figure 1), enable Loudoun Water to plan for, communicate, and take actions that align with defined pathways, while still remaining flexible to changes in external factors, such as market conditions, regulations, and technological advancements. The trigger-based strategies were used to create implementation plans, which are comprised of modular project components that are keyed to Loudoun Water’s Capital Improvement Plan and allow for adaptable “plug and play” of project components. Concepts reviewed in this work will demonstrate to utility managers how cutting edge innovations can be included in practical implementation plans that limit risk.
The BRWRF Master Plan was completed in December 2016. One of the triggers identified during the master planning process was met with respect to biosolids management, thus prompting a project involving increased anaerobic digester capacity, which is currently under construction. Other triggers related to the liquids treatment and reclaimed water strategies have also been realized, with related projects now being in the planning and design phase.
The BRWRF, owned and operated by Loudoun Water in Ashburn, Virginia, is an 11 mgd advanced treatment facility that employs a 5-Stage biological nutrient removal (BNR) process, followed by membrane filtration and granular activated carbon (GAC) to meet stringent monthly effluent concentration limits (e.g., 10 mg/L COD, 1.0 mg/L TKN, 0.1 mg/L TP). The BRWRF is also restricted in terms of the total mass of nutrients that can be discharged to receiving waters per year, meaning that the allowable effluent concentration of nitrogen and phosphorus will decrease as effluent flows to the receiving water increase. Additionally, the BRWRF must comply with reclaimed water requirements, as the BRWRF provides non-potable reclaimed water to multiple customers.
Prompted by rapid, continued growth in the service area and the potential for increasingly stringent effluent quality limits, Loudoun Water commissioned a Master Plan. For the purpose of developing the Master Plan, a vision specific to the BRWRF was developed (Figure 2), which indicates that the highest calling of the BRWRF is to protect the environment and the region’s public water supply, all while providing responsible financial leadership and serving the community’s interests across residential, commercial, and industrial sectors.
An iterative approach was used in the decision-making process to ensure compatibility between strategies adopted for the near- and long-term planning horizons.
• Phase 1 involved fully understanding the existing BRWRF with a view to optimizing existing assets. A calibrated whole plant process model, computational fluid dynamic model, energy model, financial model, and risk/opportunity profile were developed.
• Phase 2 involved exploring the world of options related to treatment technologies and business solutions, the initial focus being on inside the fence options. Feedback regarding decision criteria was also obtained.
• Phase 3 utilized calibrated modeling, parametric design, cost estimation and piloting in conjunction with multi-criteria decision analysis. The aim was to develop and evaluate numerous strategies that would allow for economic growth, while best leveraging existing assets, new and maturing technologies, external effluent management options, and resource recovery and energy management opportunities.
The three planning phases included over 70 workshops and meetings to discuss findings, share updates, and confirm consensus before moving forward. Workshop facilitation was carried out by a mix of conventional and innovative approaches to ensure that findings were being effectively disseminated and that the unique perceptions, experiences, and valuation structures of Loudoun Water staff were being accounted for. For example, real-time electronic polling was used to inform the development of appropriate decision making criteria and their associated weightings of importance from Loudoun Water’s point of view. Additionally, Loudoun Water convened a Technical Advisory Panel (TAP) to challenge the thinking of the project team; the TAP review process allowed for fresh insights and confirmation of the comprehensiveness of the planning process.
SELECTED OUTCOMES OF THE PLANNING PROCESS
Outcomes from the BRWRF master planning process included decisions to increase anaerobic digestion volume and to monitor the maturation of sludge pretreatment technologies; to move toward next generation nutrient removal using a phased approach; to continue the production of high quality effluent for non-potable reuse and surface water augmentation; and to pursue nutrient and energy recovery projects based on market triggers.
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