Retrofitting LID practices into existing neighborhoods: Is it worth it?

Timothy J Wright, Purdue University

Abstract

Low impact development (LID) practices are gaining popularity as a way to manage stormwater close to the source. This reduces infrastructure requirements and helps to maintain hydrologic processes close to predevelopment conditions. Studies have shown LID practices to be effective in reducing runoff and improving water quality. However, little has been done to aid decision makers in selecting the most effective practices for their needs and budgets. To this end, the L-THIA LID model has been applied. Using readily available data sources, multiple scenarios can quickly be examined, and then analyzed to determine the cost of implementation and the approximate period needed to see a return on the investment. This has been demonstrated by modeling four neighborhoods in greater Lafayette, Indiana using the L-THIA LID model to estimate the levels of runoff reduction that could be achieved through retrofitting LID practices. Based on LID practice cost of implementation, the payback period was determined for each practice. Depending on the LID practice and adoption level, 10 to 70 percent reductions in runoff volumes could be achieved. Cost per cubic meter of runoff reduction was highly variable depending on the LID practice and the land use it was applied to, ranging from around $3.00 to almost $600.00. In some cases the savings from reduced runoff volumes paid back the LID practice cost with interest in less than 3 years, while in other cases it was not possible to generate a payback. This information can help decision makers establish realistic goals and make informed decisions regarding LID practices before moving into detailed designs, thereby saving time and resource..

Degree

M.S.

Advisors

Engel, Purdue University.

Subject Area

Hydrologic sciences|Civil engineering|Sustainability|Urban planning

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