Sec. 35-F142. - Specific Standards.
In all areas of special flood hazards where base flood elevation data has been provided in accordance with this ordinance, the following provisions are required:
(a) Residential and Other Habitable Construction.
(1) Work on habitable structures within the FEMA effective and regulatory floodplain may be allowed as follows:
A. Rehabilitation, repair, or addition that does not constitute substantial improvement is allowed.
B. Rehabilitation, repair, or addition that constitutes a substantial improvement is allowed only if the structure is elevated so that the finished floor is at least one foot (1') above the regulatory floodplain.
C. Lateral additions that are not structurally connected to the existing building are allowed if the addition is at least one foot (1') above the regulatory floodplain. The existing building does not have to be elevated in this case.
D. An accessory detached dwelling unit (ADDU) may be constructed in the effective or regulatory floodplain only if the principal dwelling was constructed outside the effective or regulatory floodplain or if the lot was platted prior to the date of the current effective or regulatory floodplains (dated September 30, 2010 or later). The accessory detached dwelling unit must be at least one foot (1') above the effective or regulatory floodplain. Applicant must meet the criteria in subsections (E) through (I) below. Reference Sec. 35-371 for information related to Accessory and Principal Dwellings.
E. The Floodplain Administrator may deny a permit for new or substantially improved habitable structures if the project site or vicinity has a history of high-water rescues, repetitive losses, or other historical flooding issues.
F. Applicant will be required to submit flood studies confirming that the proposed construction will not cause a rise in the floodplain, grading plans to confirm that adjacent properties will not be impacted, certification that structures can withstand hydrostatic and hydrodynamic forces, and scour analysis as applicable prior to approval of the permit.
G. Applicant will submit a pre-construction elevation certificate for any substantial improvement, lateral addition not structurally connected, and/or ADU prior to approval of the permit.
H. Applicant will submit a post-construction elevation certificate for any substantial improvement, lateral addition not structurally connected, and/or accessory detached dwelling unit prior to final inspection/certificate of occupancy.
I. Depending on the proposed design and the building type, the applicant must meet all FEMA requirements related to crawl space, enclosures, openings, etc. Reference the FEMA NFIP Elevation Certificate and Instructions, 2019 Edition or subsequent updates.
(2) New mixed-use structures (habitable and commercial, parking garage, etc.) may be constructed in the FEMA effective and/or regulatory floodplain under the following conditions:
A. When located in the RIO district, or on redevelopment property as defined on the Limited Permissible Development Map maintained by the Floodplain Administrator; and
B. The lowest finished floor is at least one foot (1') above the regulatory floodplain and/or meets floodproofing requirements per FEMA requirements; and
C. Parking garages cannot accept surface flow from outside the structure; and
D. All other aspects of this ordinance are met.
(b) Nonresidential Construction.
(1) The following restrictions will be placed on nonresidential, commercial, industrial, and other non-habitable construction in the floodplain:
A. Demonstrate that no alternative sites are available for development within the property that is out of the floodplain.
B. Structures shall have either (a) the lowest floor, including basement, elevated to one (1) foot above the regulatory floodplain, (or its energy grade line (EGL), whichever is higher) or (b) have the lowest floor, including basement, with attendant utility and sanitary facilities, be floodproofed so that below the regulatory floodplain level plus one (1) foot above the lowest floor, the structure is watertight with walls substantially impermeable to the passage of water and with structural components having the capability of resisting hydrostatic and hydrodynamic loads and the effects of buoyancy.
C. Demonstrate that the development will not be subject to damage from hydrostatic or hydrodynamic forces, debris impact, soaking, sediments, and contaminants.
D. New construction and substantial improvements, with fully enclosed areas below the lowest floor that are usable solely for parking of vehicles, building access or storage in an area other than a basement and which are subject to flooding shall be designed to automatically equalize hydrostatic flood forces on exterior walls by allowing for the entry and exit of floodwaters. Designs for meeting this requirement must either be certified by a registered professional engineer or meet or exceed the following minimum criteria.
A minimum of two (2) openings on separate walls having a total net area of not less than one (1) square inch for every square foot of enclosed area subject to flooding shall be provided.
E. Electrical heating, ventilation, plumbing and air-conditioning equipment and other service facilities shall be designed and/or located so as to prevent water from entering or accumulating within the components during conditions of flooding.
F. A registered professional engineer shall submit a certification to the floodplain administrator that the standards of this subsection are satisfied. The certification shall include a statement to the effect that the engineer has developed and/or reviewed structural design, specifications, and plans for the construction and finds them to be in accordance with this subsection. A record of such certification which includes the specific elevation (in relation to mean sea level) to which such structures are floodproofed shall be maintained by the floodplain administrator. The director of public works shall utilize the floodproofing regulations prepared by the United States Army Corps of Engineers and/or FEMA as a guide in determining construction requirements.
G. An increase in water surface elevation may be permitted on the developer's property only if all the requirements of 35-F124(c) are met.
H. If the subject site does not meet the Unflooded Access criteria per H6.2.9, a variance to H6.2.9 shall be required. In addition to the variance, the applicant shall be required to 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 the floodplain administrator's direction.
I. Complete the Conditional and/or Letter of Map Revision process for the development, if applicable.
J. The owner shall indemnify the City of San Antonio against damages resulting from flooding on the owner's property or subject site.
K. Other site-specific restrictions and/or requirements deemed appropriate by the floodplain administrator.
(c) Manufactured Homes.
(1) Construction/installation of manufactured homes within the regulatory floodplain is not allowed.
(2) Replacement of a manufactured home is only allowed in the floodplain if the previous home was constructed outside the effective or regulatory floodplain or if the lot was platted prior to the date of the current effective or regulatory floodplains (dated September 30, 2010 or later) and if the finished floor of the new home is at least one foot (1') above the regulatory floodplain, if the home is anchored to prevent flotation, and not located in an area of repetitive loss or an area of high-water rescues. Skirting must be breakaway or have proper openings per FEMA guidelines.
(3) Construction/installation of manufactured homes must meet all applicable federal regulations and guidelines including those specific to federal loans.
(d) Floodways. Located within the areas of special flood hazard are areas designated as floodways. Since the floodway is an extremely hazardous area due to the velocity of floodwaters which carry debris, potential projectiles and erosion potential, the following provisions shall apply:
(1) Encroachments are prohibited, including fill, new construction, substantial improvements and other developments within the adopted regulatory floodway, unless certification by a registered professional engineer is provided demonstrating that encroachments shall not result in any increase in flood levels during occurrence of the regulatory discharge.
(2) If subsection (1) above is satisfied, all new construction and substantial improvements shall comply with all applicable flood hazard reduction provisions of this ordinance.
(3) The placement of any manufactured home is prohibited.
(e) Recreational Vehicles. Require that recreational vehicles placed on sites within Zones A1-30, AH, and AE on the community's FIRM either (i) be on the site for fewer than one hundred eighty (180) consecutive days, or (ii) be fully licensed and ready for highway use, or (iii) meet the permit requirements of Article 4, Section C(1), and the elevation and anchoring requirements for "manufactured homes" in paragraph (4) of this section. A recreational vehicle is ready for highway use if it is on its wheels or jacking system, is attached to the site only by quick disconnect type utilities and security devices, and has no permanently attached additions.
(f) Storage of Equipment and/or Materials. Equipment and/or materials should be stored outside of the FEMA effective floodplain. If equipment and materials are stored within the limits of the floodplain, the following provisions apply:
(1) A Floodplain Development Permit (FPDP) is required.
(2) Hazardous materials must be stored at least one foot (1') above the regulatory floodplain (including new permanent propane tanks).
(3) Non-hazardous materials and equipment must be stored at least one foot (1') above the regulatory floodplain, or stored within a floodproofed building, or must be anchored to prevent flotation from the property during a flood event.
Limited Permissible Development Map (LPDM Maps)
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(Ord. No. 95415 § 1 Attachment A) (Ord. No. 2010-10-14-0894, § 2, 10-14-10) (Ord. No. 2010-11-18-0985, § 2, 11-18-10)(Ord. No. 2015-12-17-1077, § 2, 12-17-15; Ord. No. 2022-11-03-0831, § 2, 11-3-22, eff. 1-1-23)
