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Case Study: Installation and Monitoring of Green Infrastructure Stormwater Controls in Louisville, Kentucky (Abstract)
Citation:
Brown, R. A., M. BORST, H. Kazemi, J. Gray, AND L. Kurtz. Case Study: Installation and Monitoring of Green Infrastructure Stormwater Controls in Louisville, Kentucky (Abstract). Presented at ASCE-EWRI World Environmental and Water Resources Congress, Albuquerque, NM, May 20 - 24, 2012.
Impact/Purpose:
To inform the public.
Description:
In 2005, the Louisville and Jefferson County Metropolitan Sewer District (MSD) entered into a Consent Decree with the U.S. Environmental Protection Agency (EPA), Kentucky Dept. of Environmental Protection, and the U.S. Department of Justice. In 2009, the MSD submitted the Integrated Overflow Abatement Plan (IOAP) to address combined sewer overflows (CSOs) and sanitary sewer overflows. As part of the IOAP, the MSD performed a cost/benefit analysis for each overflow location to determine the highest value overflow reduction project. The MSD modeled solution alternatives for CSO abatement and completed a cost/benefit analysis for each alternative. 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 part of the IOAP, the MSD committed to incorporate ‘green’ solutions to downsize the downstream ‘gray’ solutions, when cost effective. The MSD committed to monitor the performance and effectiveness of the green infrastructure stormwater controls to assure ongoing reductions of stormwater volume entering the system. The MSD will base later decisions of incorporating green infrastructure into the plans based on monitoring results of initial installations. EPA’s Urban Watershed Management Branch and the Center for Infrastructure Research at the University of Louisville are collaborating with the MSD and URS Corporation to monitor the individual performance of selected controls and evaluate the overall effectiveness of the collective green infrastructure stormwater controls. For CSO basin #130, an 11 ha (28-acre) sewershed, URS designed a plan comprised entirely of green infrastructure controls. The plan was developed by modeling green controls with InfoWorks, a combined sewer hydraulic model, to meet the same regulatory targets as outlined in the IOAP. Twelve permeable interlocking concrete pavement (ICP) systems and 29 tree boxes will be installed starting in November 2011. The ICP systems are 2.4 m (8-ft) wide, range in length from 16.8 to 39.6 m (55 to 130 ft), and will be installed in the parking lanes of roads leading to four targeted intersections. These sites will be instrumented with time domain reflectometers, water level sensors, thermistors, and passive capillary lysimeters (drain gauges) at various depths in the profile to evaluate the hydrologic performance of the individual controls. Infiltration rates into the surface of the ICP will also be measured at least once per quarter and immediately before and after maintenance. Before the installation of the stormwater controls, the MSD continuously measured flow rates at multiple locations within the basin, including the overflow location. They will continue to measure flow rates at these locations after construction of the stormwater controls. The results from evaluating the individual controls will be combined with basin-wide monitoring and modeling to determine the overall effectiveness of installing green infrastructure stormwater controls to reduce CSO volume and frequency and to reduce stormwater discharge. This case study will provide an overview on the design, construction, and monitoring used to evaluate these controls, and preliminary data will be presented as available.
