DEPARTMENT: Transportation & Capital Improvements
DEPARTMENT HEAD: Razi Hosseini, P.E., R.P.L.S.
COUNCIL DISTRICTS IMPACTED: Citywide
SUBJECT: Unified Development Code (UDC) Amendment to Adopt Atlas 14 Rainfall Data into the Storm Water Design Criteria Manual
SUMMARY:
An ordinance approving an amendment to Chapter 35 of the City of San Antonio Municipal Code, the Unified Development Code, to incorporate Atlas 14 rainfall data into the Storm Water Design Criteria Manual.
BACKGROUND INFORMATION:
Atlas 14 is a study of rainfall frequency and intensity. The most recent study (Atlas 14, Volume 11), which includes Texas, was published by the National Oceanic and Atmospheric Administration (NOAA) in September 2018. Transportation & Capital Improvements (TCI) proposes to implement Atlas 14 rainfall data through a Unified Development Code (UDC) Amendment to comply with federal and local standards that require the use of the best available data for drainage and floodplain design. The proposed amendment includes increasing design rainfall depths by 10-30% for the 100-year (1% annual chance) storm when compared to previously accepted studies.
TCI, in coordination with the Bexar Regional Watershed Management (BRWM) partnership and its Watershed Technical Committee (WTC), led a thorough stakeholder engagement process to assess the implications of implementing Atlas 14. The WTC included staff from TCI, Bexar County, and the San Antonio River Authority (SARA). The WTC discussed and reviewed impacts associated with flood risk reduction policies and programs, capital project development and delivery, land development, coordination with floodplain mapping efforts and implications for the community.
In the summer of 2018, TCI organized the Atlas 14 Land Development Stakeholder Group consisting of more than two dozen members, including representatives from TCI, Development Services Department (DSD), Texas Department of Transportation (TxDOT), Bexar County, SARA, Real...
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