Title
Consider an ordinance amending Chapter 36, Section 36-180, Code of Ordinances (2010 Edition), regarding on-site detention facilities. (Second Reading)
Body
This is the fourth and final code amendment City Council will consider at this meeting regarding the Round Rock Zoning and Development Code. The purpose of this amendment is to modify the requirements for on-site storm water detention.
Currently all developments that are required to detain storm water on-site are required to do so in a pond designed to accommodate up to the 4% annual chance storm event (sometimes referred to as a 25-year flood), while developments in or upstream of areas with known flooding issues are required to accommodate up to the 1% annual chance storm event (sometimes referred to as a 100-year flood). The amendment will require all on-site detention ponds to accommodate up to the 1% annual chance storm event, regardless of geography and known flood issues. The effect is that detention ponds will have to be slightly deeper or larger to hold more water. However, the increase in pond size required to accomodate the larger storm event is not considered significant as per staff analysis, which was also verified with local civil engineers.