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Case Studies

The Northeast Ohio Regional Sewer District’s GI Plan for Cleveland

As the city of Cleveland, OH works to manage its stormwater in a more sustainable way and renew abandoned urban properties characterized by post-industrial blight, the Northeast Ohio Regional Sewer District (NORSD) is contributing significantly by developing and implementing a Green Infrastructure (GI) Plan.  Overflow of stormwater into sewer systems spikes the “billions of gallons of raw, untreated sewage [that annually] spill into Lake Erie and nearby rivers” from the Cleveland metropolitan area.  To help reduce this burden on the local water resources, the EPA and the State of Ohio filed a consent decree with the NORSD in 2011 that describes “specific combined sewer overflow (CSO) control measures, reduction quantities, performance goals and construction and monitoring measures the [NORSD] will be required to perform over the next 25 years,” with assistance from public and nonprofit partners.  The agreement requires the NORSD to spend a minimum of $42 million within 8 years on site-specific GI projects to control 44 million gallons of CSO that would otherwise be managed via gray infrastructure.  Qualifying GI structures may include but are not limited to “bioretention and extended detention wetland areas as well as green roofs and cisterns” and are expected to be more cost-effective than the “upsizing” of the existing gray infrastructure that would be required to achieve the same CSO control benchmarks.

The GI Plan addresses geographic coverage (location and prioritization of projects within the combined sewer area); preservation of practices, ownership, and access according to the law; public participation in decision-making; implementation scheduling; methods for measuring achievement of performance standards including hydrologic and hydraulic modeling; environmental justice considerations; and operation and maintenance activities including schedules and information management procedures.   To decide coverage, NORSD devised models to choose locations with “high remaining [CSO] outflow volumes,” available land, and the potential to improve socioeconomic conditions in low income or concentrated minority populations.  They considered a number of environmental and contextual metrics and ranked candidate areas.  It was important if the land was not publicly owned to be able “to ensure permanent access and sufficient control of GI control measures after construction […] to allow for the inspection, operation, and maintenance of GI control measures in perpetuity”.  The NORSD chose 38 priority areas (spatially depicted below in a map image from their GI Plan) for GI improvements  based on their models’ output, devised the most suitable GI projects for those areas, and ranked them based on performance and feasibility while allowing regional stakeholders to voice their opinions in order to create a prioritized list of the projects.   Their proposal, if carried out fully, is anticipated to “eliminate an estimated 95 million gallons of stormwater annually from the sewer system [, i.e.,] double what regulators required.”

 

 

On January 13th, 2013 the NORSD will meet with federal officials seeking approval of their GI plan.  Pending approval, the 2011 GI Plan will be followed by detailed site-specific pricing and engineering plans.  These plans will be carried out upon successful acquisition of necessary properties and easements, with first construction beginning in 2012.  Construction is slated to be completed within 8 years and demonstrated to be effective within 10 years, according to the depicted schedule (to be followed by ongoing operation, maintenance, and monitoring):

 

If approved, the NORSD anticipates and plans to assess a variety of positive outcomes of their multifunctional GI projects, including the mitigation of stormwater flows; life-cycle cost savings as compared to gray infrastructure alternatives; ecological benefits and ecosystem services including habitat improvements, flood reduction, and erosion control; increased property values; improved quality of life for low-income and minority neighbors with additional maintained neighborhood amenities;  recreational benefits; energy savings; reduction of carbon footprint; air quality benefits; neighborhood aesthetic improvements; and job growth–a myriad of benefits enjoyed by the greater Cleveland region and its surrounding natural resources.

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