Buildings and parking areas are prohibited from being placed in the floodplain in the City of Austin, according to Land Development Code (LDC) Section 25-7-92. However, there are three sections of code that allow for exceptions and permit buildings and/or parking in the floodplain:
- 25-7-93 (General Exceptions)
- 25-7-94 (Requirements in Central Business Area)
- 25-7-95 (Requirements for Parking Areas)
The specifics of the different exceptions will be discussed in another blog post, and the remainder of this post will focus on describing the requirements that must be met in order for the exceptions to be approved.
In order to locate a building and/or parking in the floodplain in the City of Austin, your project must request a variance in accordance with land development code (LDC) section 25-7-92 (C), which requires the project to meet these seven requirements:
NOTE: (the items in bold below are not part of the code, but are an explanation of the code requirement).
- the finished floor elevation of a proposed building is at least two feet above the 100-year floodplain; (This means that the lowest level of the building is 2 feet above the local 100-year floodplain, as shown in the image below.)
- normal access to a proposed building is by direct connection with an area above the regulatory flood datum, as prescribed by Chapter 25-12, Article 1 (Building Code); (This means that a path is provided that remains above the local 100-year floodplain from the FFE to a safe location. This may be done by structurally bridging the floodplain or by grading land to provide access, as shown in the image below.)
- a proposed building complies with the requirements in Chapter 25-12, Article 1, Section 25-12-3 Appendix G (Flood Resistant Construction) and Section 1612 (Flood Loads); (This means that the project has been designed by a structural engineer to resist flood induced pressures and scouring caused by flood debris and elevations.)
- the development compensates for the floodplain volume displaced by the development; (This means that any fill placed into the 100-year floodplain, either with structural members or land or other encumbrances, it is offset with an equal volume of cut from another location on the site.)
- the development improves the drainage system by exceeding the requirements of Section 25-7-61 (Criteria for Approval of Development Applications), as demonstrated by a report provided by the applicant and certified by an engineer registered in Texas; (This means that the local drainage systems is not caused to be any further flooded by the proposed construction in the floodplain.)
- the variance is required by unique site conditions; (This means that no other solution could reasonably be expected due to site conditions), and
- development permitted by the variance does not result in additional adverse flooding impact on other property. (This means that no other property is affected by the change in floodplain conditions caused by the proposed development.)