Quantification of Sustainability Index for Underground Utility Infrastructure Projects

This paper examines environmental impact, costs, and social impacts comparing four construction techniques commonly used in the installation of underground utility infrastructure. The three impact factors are quantified to develop an overall underground sustainability index rating (USIR) for evaluating utility projects with competing installation technologies. The main contribution to the overall body of knowledge is the demonstration of a method for calculating a sustainability index that enables decision makers to quantify public works utility projects with guidance for evaluating proposed technologies based on environmental impact, costs, and social impact criteria. The aim is to help change the myopic thought process of typical public works owners who typically base contractor selection on lowest cost, rather than examining sustainability factors. An emission calculator was used in this research to quantify environmental impact by comparing six airborne emissions: carbon dioxide (CO2), carbon monoxide (CO), particulate matter (PM), nitrogen oxide (NOx), sulfur oxide (SOx), and hydrocarbons (HC). Costs were determined by estimating competing technology options including surface restoration. Social impacts were quantified by comparing and rating 13 factors affecting underground utility projects. The approach to calculating the USIR was demonstrated on a case study installation of 313m (1,026 linear feet) of 400mm (16in.) PVC sanitary sewer in a mature neighborhood in Portland, Oregon. The USIRs were compared for open-cut, pilot tube microtunneling, horizontal directional drilling, and vacuum microtunneling technology options. (C) 2013 American Society of Civil Engineers.