Green Storm-water Infrastructure Strategy Generation and Assessment Tool

Abstract

Green Stormwater Infrastructure (GSI), which includes elements like green roofs, bioretentions, pervious pavement and cisterns, has proven to be a cost effective alternative that can achieve a wider range of benefits in stormwater management compared to the single-purpose grey/traditional infrastructure (Combined Sewer System or Municipal Separate Storm and Sewer System). However, the implementation of GSI as a replacement or support system for grey infrastructure faces some barriers preventing its adoption by planners/designers and decision makers, in the private as well as in the public sector. While understanding and quantifying the full costs and the benefits of GSI plans are critical for sound decision making and to facilitate its adoption, planners/designers face challenges pertaining to hydrologic calculations (including sizing of Green Stormwater Infrastructure Elements (GSIEs), cost estimation (life cycle costs) and benefit assessment). This thesis presents a proof of concept tool (prototype) that is developed to help planners/designers and different stakeholders involved in conducting a comprehensive GSI planning process. The tool generates GSI alternative solutions (combination and size of GSIEs) that meet the user’s financial and hydrologic objectives. These alternatives are generated to maximize benefits, reduce costs and account for design specifications and multi-functionality of GSI. The prototype has three modules: An Interface Module (including Input and Output Interfaces) A Process Module for hydrology, cost and benefit calculation and an optimization model for strategy generation.A Database Module for storing collected data that are used for different process module calculations. The prototype, which is developed in Ms. Excel, was successfully tested for functionality and usability on a residential development site in Pittsburgh, PA. The prototype required minimal input from the user (site specific data) and generated strategies that double the net annual benefits compared to the plan proposed by the developer. The tool also allowed generation of strategy scenarios that responded to multiple user objectives.