It Is Easy Being Green: Spend Less Green with Green Infrastructure

In 2005 Louisville and Jefferson County Metropolitan Sewer District entered into a Consent Decree with the United States Environmental Protection Agency (EPA). In 2009 MSD submitted the Integrated Overflow Abatement Plan (IOAP) to address Sanitary Sewer Overflows (SSOs) as well as Combined Sewer Overflows (CSOs). As part of the IOAP, MSD performed a benefit/cost analysis for each overflow location to determine the highest value overflow reduction project in an average rainfall year. In order to reduce CSO frequencies, MSD modeled solution alternatives for CSO abatement and then completed a cost benefit analysis for each alternative to determine the solution with the best cost benefit ratio. The best solutions were implemented into the Long Term Control Plan. Many of these solutions involve large storage basins that capture overflows at the end of the pipe. As a part of the IOAP, MSD also committed to incorporate ‘green’ solutions to help downsize the downstream gray solutions, where this situation was cost effective. MSD defines green solutions as those that capture storm water before it enters the Combined Sewer System (CSS) and allow it to infiltrate into the ground. Gray solutions are defined as those that capture or reduce overflow volume and frequency through conveyance and storage of water once it has entered the MSD sewer system. The purpose of this paper is to describe how Louisville MSD creatively sought out, investigated, and pursued opportunities to incorporate green infrastructure into an overflow abatement plan.