American Society of Civil Engineers

Green Infrastructure Optimization Analyses for Combined Sewer Overflow (CSO) Control

by I. B. Neilson, P.E., (EMH&T, 7400 N. Shadeland Avenue, Suite 150, Indianapolis, IN 46250 E-mail: and D. Turney, P.E., (EMH&T, 5500 New Albany Road, Columbus, OH 43054 E-mail:
Section: Special LID Applications, pp. 1533-1541, (doi:

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Document type: Conference Proceeding Paper
Part of: Low Impact Development 2010: Redefining Water in the City
Abstract: The City of Indianapolis, IN is analyzing the means to effectively integrate green infrastructure Best Management Practices (BMPs) for multiple use urban revitalization and combined sewer overflow (CSO) management. Working independently within public right-of-way as well as leveraging multiple public-private relationships, the City looks to realize a variety of cost saving techniques that reduce the overall economic impact of the unfunded CSO reduction mandate. The authors highlight the planning tools, analytical techniques and results from the City’s Green Infrastructure Optimization Analyses projects for both the Pleasant Run and the Lower Pogues Run Watersheds. The Pleasant Run watershed maintains a mixed use residential, commercial and light industrial land use base. The Lower Pogues Run Watershed is the downtown, ultra urban City center of Indianapolis. The planning tools include green infrastructure sizing studies; WinSLAMM (SCS based) modeling for green infrastructure sizing and water quality treatment; RECARGA (TR-50 based) modeling for green infrastructure infiltrative design; maximizing public right-of-way for CSO abatement; Green Street-to-land use design optimization; and integrating economic revitalization, intermodal greenway linkage and CSO program requirements. The authors will highlight the use of compatible modeling platforms for the City’s regulatory compliance based SWMM CSO model. The analytical techniques include the use of the planning tools to maximize green infrastructure abatement processes within land use categories for sub-basin or modeling catchment areas. Benefit-to-Cost (B/C) analyses are defined in the comparison to traditional store-pump-treat CSO abatement processes. The B/C analyses are utilized to define the maximum green infrastructure integrated into public right of way as well as participating private entities. The localized results are extrapolated across the each watershed sub-basin in order to determine the overall benefit for use of green infrastructure for the mix of land uses.

ASCE Subject Headings:
Combined sewers
Environmental issues