Beneficial use of stormwater and land development regulation case studies in Austin, Texas

Urban development puts strain on the environment in numerous ways. Flora and fauna are pushed off the land, but more immediate to human health, the increase in impervious cover can lead to greater risks of flooding and polluted waters. The City of Austin made a commitment to the environment and managing the city’s hydrology in its 2012 Imagine Austin Comprehensive Plan. The city’s Watershed Protection Department (WPD) is working to fulfill the city’s promise by writing regulation to be included in CodeNEXT, the rewrite of the City’s land development code. The aim of this “beneficial use” regulation is to infiltrate, reuse or evapotranspire rainwater that falls on highly impervious multi-family and commercial sites within the city limits. I was hired by the WPD to conduct feasibility studies of their regulation and began by familiarizing myself with Austin’s Environmental Criteria Manual (ECM) and the history behind the proposed regulation. I first investigate the extent green stormwater control measures (GSCMs) laid out in the ECM can be implemented on existing sites in the city of varying degrees of impermeability selected by WPD staff. Starting from city archived site plans and shapefiles, I place GSCMs spatially in ArcGIS and use the ECM to determine whether the beneficial use volume threshold set by the city could be met for each site. Finally, I discuss how the findings of my study led to a simplification of the proposed regulation.