“Communities of the Future” – Leveraging an Integrated Municipal Stormwater and Wastewater Planning Framework for Next Generation Utility Management and Community Vitality

The CSO ProblemIn August 2010, the Metropolitan Sewer District of Greater Cincinnati (MSDGC) entered into a consent decree with the USEPA committing to reduce and control the nearly 12 billion gallons of combined sewer overflow (CSO) discharged to surface waters annually. In designing its wet weather improvement program to comply with the consent decree, MSDGC saw an opportunity to simultaneously build the sustainability of the communities it serves. Project Groundwork, as MSDGC's wet weather improvement program (WWIP) is called, has the primary goal to reduce CSOs and improve water quality, but its dual purpose is to leverage MSDGC investment towards economic development and urban renewal. This wet weather strategy adopted by MSDGC was in line with the then forthcoming USEPA “Integrated Municipal Stormwater and Wastewater Planning Approach Framework”, which supports the flexible and prioritized approach to achieving water quality.Integrating Wet Weather Planning and Water Quality ManagementOne of the key approaches for Project Groundwork is source control to manage both water quantity and water quality in the MSDGC service area. This entails managing the source of pollutants within a watershed which contribute to water quality impairment, as well as managing the wet weather conveyance in the combined sewer system by offloading and separately conveying stormwater flow. This approach was utilized to evaluate alternative wet weather solutions in several MSDGC watersheds. One of Project Groundwork's largest activities is within the Lick Run Watershed, which contributes about 1 billion gallons of CSO annually into the Mill Creek. One of only a few similar projects in the country, the Lick Run project serves as a demonstration for MSDGC's approach of utilizing source control as the foundation for its WWIP. Both quantity and quality control strategies have been identified including sewer separation, detention ponds, forebays, bioinfiltration areas, reforestation and the restoration of natural open conveyance systems within the watershed. USEPA has highlighted the Lick Run project as “promising” in its use of green infrastructure to control CSO discharges. In December 2012, MSDGC submitted to USEPA this project along with a number of others within the Lower Mill Creek basin as alternatives to the default consent decree project of a deep tunnel. In May 2013, USEPA approved the alternative strategy which is now officially known as the Revised Original Lower Mill Creek Partial Remedy (LMCPR).Developing an Integrated Plan for MSDGC WatershedsThe USEPA Integrated Planning Framework identifies six key elements to developing, implementing and adapting an integrated municipal stormwater and wastewater plan for water quality improvement:Element 1 – Existing Water Quality, Human Health and Regulatory IssuesElement 2 – Existing Wastewater and Stormwater Systems PerformanceElement 3 – Community Stakeholder CommunicationElement 4 – Alternatives Analysis, Selection and Proposed ImplementationElement 5 - Measuring SuccessElement 6 – Improvements to the PlanMSDGC's integrated planning approach, outlined in its “Integrated Sustainable Watershed Management Manual” (October 2012) and referred to as the Sustainable Watershed Evaluation Planning Process (SWEPP), embraces each of these elements to create a comprehensive strategy based on an understanding of existing conditions, the water quality challenges, input and collaboration with stakeholders and partners, robust alternatives analysis and recommendations, and processes to measure success and adaptively manage the plan long-term. The Lower Mill Creek basin, the focus of Phase 1 of the WWIP, was evaluated for sustainable and lower cost solutions to the consent decree default strategy of mainly consolidation sewers, deep tunnels and an EHRT. This alternative strategy, now approved by USEPA, was developed collaboratively with public and private partners.In the Lick Run watershed, approximately 1 billion gallons of CSO are discharged to the Mill Creek in the typical year. With the implementation of the alternative integrated strategy which is based on source control, the CSO volume is estimated to be reduced by an estimated 624 million gallons in the typical year. Another water quality benefit of the sustainable alternative within the Lick Run watershed includes significant potential pollutant load reduction for nutrients (Total Phosphorus and Total Nitrogen), Total Suspended Solids and bacteria due to the proposed stormwater control measures or best management practices (BMPs). Other benefits include community collaboration on sustainable infrastructure solutions which also can represent community assets, attraction of diverse funding sources, public education and outreach opportunities, and connectivity to community plans for the future. The cost competitiveness of the alternative solution is also attractive; the default consent decree project suite was estimated to be $537M (2006 dollars) while the sustainable alternative for the Lower Mill Creek is $317M (2006 dollars). The final alternative strategy approved by USEPA includes selected alternative projects which will eliminate 1.78 billion gallons of CSO at an estimated cost of $244.3M (2006 dollars) and must be implemented by December 2018.The SWEPP was developed by MSDGC through this alternatives evaluation process and now presents a framework for adaptively managing the subsequent phases of the WWIP and prioritizing improvements to address key water quality needs. Watershed evaluations have been initiated for other areas of the service area and are yielding promising results for alternative wet weather and water quality management solutions.