Improving Sustainability of Urban Streets via Rain Gardens – How Effective Are These Practices in the Pacific Northwest?
PI: Meghna Babbar-Sebens (OSU), meghna@oregonstate.edu
Dates: 07/01/2013 – 7/31/2015
Final Project Report: PacTrans-46-OSU-Babbar-Sebens
Stormwater managers and engineers are required to evaluate the effectiveness of any best management practice (BMP) that is implemented by a city on its roadways. While artificial drainage systems are easier to evaluate, natural drainage systems are more challenging because of the variability in the design of the system itself. Better monitoring and evaluation methods are needed to evaluate the performance of such systems in the Pacific Northwest climate, since they are also sensitive to the runoff flows they receive and to the climate in the region they are installed. The Northwest Environmental Defense Center (NEDC) and the Oregon Department of Transportation (ODOT) are currently expending approximately $2.1 million in funds per year (from FY 2011- FY 2014) for stormwater retrofit programs not associated with highways within the Willametter River watershed. The City of Corvallis is one of the cities that is recipient of this funding and is also working on a city-wide design of a system of raingardens. One of the settlement agreement criteria between NEDC and ODOT include monitoring of BMP effectiveness. Most literature available on rain garden monitoring and assessing effectiveness do not explain how the design parameters of the rain gardens interact with the wet-dry climate found in the Pacific Northwest. Hence, investigations are needed to assess the long term effectiveness of rain gardens for stormwater drainage, assess effect of rainfall intensities and duration on individual rain garden design and on a system of rain gardens, assess effectiveness of these systems when they are placed on primary, secondary, and tertiary roadways, and develop engineering standards for stormwater retrofits that use such systems. Such investigations are also needed to demonstrate the impact and success of capitol investment made by these pacific northwest agencies for improving stormwater collection systems.
