Practical Tool for the Design and Cost Optimization of Permeable Pavements in the Planning Stage of Stormwater Management

Abstract

To address issues created by increased stormwater runoff, there is growing interest in sustainable tools such as permeable pavement (PP), which is a green infrastructure (GI) practice. This paper outlines the development and application of a design tool called the “cost optimization tool for permeable pavements (COTPP).” This tool aims to help states, municipalities, and consultants design PPs using reliable hydrological and structural pavement design methods. The COTPP uses a cost optimization algorithm similar to a heuristic search that helps identify which combination of PPs, conventional pavement, and other GIs provides the most economic value. A sensitivity analysis was conducted using the tool, which consisted of designing the three main types of PP using varying design inputs and comparing the COTPP’s results to results from an existing design tool or guidelines. The average percent differences between the COTPP’s results and that of other methods were below 10% for the structural designs and around 15% for the hydrological designs. The differences were caused by the use of a safety factor in the hydrological design and other adjustments to design methods. It was concluded that the tool is reliable and can be confidently used by designers. The tool was then used for a representative case study site (PP parking lot) in which the actual design and cost estimates of on-site components were known. The COTPP was able to identify other design alternatives that helped reduce the actual construction cost of the existing parking lot from $305,918 to as low as $238,790.