§ 35-F124. Allowable Development Within the Regulatory Floodplain.  


Latest version.
  • This ordinance shall only apply to areas of special flood hazard within the jurisdiction of the city and where applicable in its area of extraterritorial jurisdiction.

    (a)

    Reserved.

    (b)

    Reserved.

    (c)

    An increase in water surface elevation is permitted solely when all the following conditions are met:

    1.

    Property owner owns both sides of the floodplain.

    2.

    The increase in the regulatory floodplain is contained in a dedicated drainage easement or right-of-way as required per subsection 35-504(d)(3).

    3.

    Increase in water surface elevation for the 1% annual chance floodplain does not exceed six (6) inches.

    4.

    No increase in water surface elevations or velocities upstream and downstream outside of the owner's property limits.

    (d)

    Account for increase in discharge due to loss of storage in all reclamation analyses.

    (e)

    Demonstrate that the development will not increase the regulatory 1% annual chance floodplain velocities above six (6) fps. No increase in velocity will be permitted if predevelopment velocities in the floodplain exceed six (6) fps unless proven that the existing channel/creek is stable (i.e., rocky bottom channel/creek) and no signs of erosion or scour are occurring in predevelopment conditions.

    (f)

    The following development may be allowed in the regulatory 1% annual chance and will require a floodplain development permit (see section 35-B106 for permit requirements):

    (1)

    All-weather street crossings that meet the requirements of subsection 35-504(g)(7).

    (2)

    Utility construction.

    (3)

    Parks.

    (4)

    Greenways.

    (5)

    Recreational facilities and golf courses.

    (6)

    Hike and bike trails.

    (7)

    Drainage improvements that mitigate existing or anticipated flood hazards.

    (8)

    Publically funded capital improvement projects that reduce flooding to protect the public safety.

    (9)

    Maintenance activities necessary to maintain the stormwater conveyance of the floodplain.

    (10)

    Drainage infrastructure repair.

    (11)

    Floodplain restoration.

    (12)

    Wetland reestablishment, mitigation, or environmentally friendly design criteria (i.e. Natural channel design, Low-Impact Development, etc., set forth by the San Antonio River Authority and/or U.S. Army Corps of Engineers).

    (13)

    Habitat re-establishment.

    (14)

    Installation of flood monitoring controls - rain gages, early flood warning systems, high water detection systems, etc.

    (15)

    Installations of emergency devices necessary to warn alarm and protect citizens at flood hazards.

    (16)

    Improvements to a structure that do not fall under the definition of substantial improvement.

    (17)

    Elevating and/or floodproofing structures in the floodplain.

    (18)

    1% annual chance floodplain reclamation where the watershed drainage area is less than three hundred twenty (320) acres when the floodplain storage volume lost due to fill is offset by comparable excavation within the same floodplain (see subsections 35-F124(d) and 35-F124(f)(27). In addition, all federal, state, or local permits shall be obtained, including Section 404 of the Federal Water Pollution Control Act Amendments of 1972, 33 U.S.C. 1334 (see subsections 35-F122 (a)(3)).

    (19)

    Parking lot construction where water depths do not exceed six (6) inches during a future 1% annual chance storm event.

    (20)

    1% annual chance floodplain reclamation in areas of ineffective flow where floodplain storage volume lost to reclamation is offset by comparable excavation within the same creek floodplain. (See subsections 35-F124(d) and 35-124(f)(27).)

    (21)

    1% annual chance floodplain reclamation in overbank areas subject to extensive shallow (0'—3') flooding where velocities in the overbank area are less than three (3) fps and where floodplain storage volume lost to reclamation is offset by comparable excavation within the same creek floodplain (see subsections 35-F124(d) and 35-F124(f)(27).) Where a maximum amount of fill allowed in the overbank areas is no more than three (3) feet with engineered slope stability calculations.

    (22)

    Historic structure reconstruction, rehabilitation or restoration.

    (23)

    Development in the low risk flood area, as defined by appendix A or subject to the requirements of section 35-F145.

    (24)

    Reclamation between the 1% annual chance floodplain and the regulatory 1% annual chance floodplain.

    (25)

    Reserved.

    (26)

    Nonresidential construction. The following restrictions will be placed on nonresidential construction in the floodplain:

    A.

    Demonstrate that no alternative sites are available for development within the property that is out of the floodplain.

    B.

    Meet all the requirements of subsection 35-F142(b), Nonresidential construction.

    C.

    Ensure the lowest finished floor elevation and/or the height to which the building must be floodproofed is no lower than the higher elevation of the energy grade line or the water surface elevation plus one (1) foot of the regulatory 1% annual chance floodplain.

    D.

    An increase in water surface elevation may be permitted on the developer's property if the floodplain is contained in a dedicated drainage easement or right-of-way. If all the requirements of 35-F124(c) are met.

    E.

    Reserved.

    F.

    Demonstrate that the development will not increase the 1% annual chance floodplain postdevelopment velocities above six (6) fps. No increase in velocity will be permitted if predevelopment velocities exceed six (6) fps.

    G.

    Demonstrate that the development will not be subject to damage from hydrostatic or hydrodynamic forces, debris impact, soaking, sediments and contaminants.

    H.

    Provide, operate and maintain an early flood warning system for the development. Warning systems will be subject to periodic inspection by the City of San Antonio to ensure they are maintained and operated as intended as per floodplain administrator's direction.

    I.

    Complete the Letter of Map Revision process for the development.

    J.

    The owner shall indemnify the City of San Antonio against damages resulting from flooding on the owner's site.

    K.

    Other site-specific restrictions and/or requirements deemed appropriate by the floodplain administrator.

    (27)

    Construction in areas of flood inundation must meet the requirements of section 35-F141, General Standards. Structures associated with park and recreation development (fences, open construction type bleachers, concession stands etc.) may be permitted in areas of flood inundation. Keep this construction out of the flood conveyance section of the floodplain. Compensate for loss of storage. Secure structures to minimize damage from hydrostatic or hydrodynamic forces (including buoyancy) and debris impact.

(Ord. No. 2008-09-11-0789, § 2, 9-11-08) (Ord. No. 2009-01-15-0001, § 2, 1-15-09) (Ord. No. 2009-08-20-0661, § 3, 8-20-09) (Ord. No. 2010-10-14-0894, § 2, 10-14-10)(Ord. No. 2015-12-17-1077 , § 2, 12-17-15)