A. All new and replacement water supply and sanitary sewage systems shall be designed to minimize or eliminate:
1. Infiltration of flood waters into the systems; and
2. Discharge from the systems into flood waters.
B. On-site waste disposal systems shall be located to avoid impairment to them, or contamination from them during flooding.
C. Crawlspace Construction. This sub-section applies to buildings with crawl spaces up to 2 feet below grade. Below-grade crawl space construction in accordance with the requirements listed below will not be considered basements.
1. The building must be designed and adequately anchored to resist flotation, collapse, and lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy. Crawl space construction is not allowed in areas with flood velocities greater than 5 feet per second unless the design is reviewed by a qualified design professional, such as a registered architect or professional engineer;
2. The crawl space is an enclosed area below the BFE and, as such, must have openings that equalize hydrostatic pressures by allowing for the automatic entry and exit of floodwaters. For guidance on flood openings, see FEMA Technical Bulletin 1-93;
3. Portions of the building below the BFE must be constructed with materials resistant to flood damage. This includes not only the foundation walls of the crawl space used to elevate the building, but also any joists, insulation, or other materials that extend below the BFE; and
4. Any building utility systems within the crawl space must be elevated to one foot or more above BFE or designed so that floodwaters cannot enter or accumulate within the system components during flood conditions.
5. Requirements for all below-grade crawl space construction, in addition to the above requirements, shall include the following:
a. The interior grade of a crawl space below the BFE must not be more than 2 feet below the lowest adjacent exterior grade (LAG), shown as D in figure 3 of FEMA Technical Bulletin 11-01;
b. The height of the below-grade crawl space, measured from the interior grade of the crawl space to the top of the crawl space foundation wall must not exceed 4 feet (shown as L in figure 3 of FEMA Technical Bulletin 11-01) at any point;
c. There must be an adequate drainage system that removes floodwaters from the interior area of the crawl space within a reasonable period of time after a flood event, not to exceed 72 hours; and
d. The velocity of floodwaters at the site should not exceed 5 feet per second for any crawl space. For velocities in excess of 5 feet per second, other foundation types should be used, or the foundation must be designed and reviewed by a qualified design professional.
(Ord. 16-2154, § 1 (part), 2016; Ord. 1412, Exhibit A (part), 1987; Ord. 1002, § 1.1 (part), 1980)