Implementation of a Green Infrastructure Program to Comply with a Unique CSO Consent Decree Requirement

The Northeast Ohio Regional Sewer District is implementing Project Clean Lake, a $3 billion, 25-year capital program that once complete, will provide treatment to over 98% of wet weather flows in the combined sewer system. Project Clean Lake includes gray infrastructure -- such as wastewater treatment plant and pump station upgrades, deep tunnel systems, and relief sewers -- and green infrastructure. The green infrastructure component of the District's program is referred to as Appendix 3 of the CSO Consent Decree. Appendix 3 required the District to identify, plan, and construct green infrastructure projects that control an additional 44 million gallons of wet weather CSO volume in the typical year, at a cost of $42 million.This paper explores how the unique 'post-gray' volumetric requirement of Appendix 3 required creative approaches to identifying candidate locations for green infrastructure projects.