Title 20 · Chapter 20 - FLOOD DAMAGE PREVENTION

Development in special flood hazard areas and nonspecial flood hazard areas

Section: 20-3

For all development within special flood hazard areas and nonspecial flood hazard areas, the building official or his/her designee shall:

(1)

Require permits for all proposed construction, development or other improvements within said areas; and

(2)

Review permit applications for construction, development or other improvements within said areas to determine that the proposed activities:

Use flood damage-resistant materials and have utility equipment which are resistant to flood damage; and

Have drainage that demonstrate retention of rainwater within surrounding property lines. The drainage calculations shall be based on a 100-year storm, per design standards of the Miami-Dade County Public Works Manual - Part 2 - Design and Construction - WC 1.1 Rainfall Intensities - 5 min. to 24 hrs. (Rainfall intensities) from the Miami-Dade County Public Works Manual with concentration times described below:

For residential use, with fewer than four dwelling units, the drainage calculation must be based on a eight-hour time of concentration.

For residential use, with four or more dwelling units, and all other uses, the drainage calculation must be based on a one-half-hour time of concentration.

(3)

Review permit applications for new construction or substantial improvements within said areas to assure that the proposed construction:

Is protected against flood damage;

Is designed (or modified) and anchored to prevent flotation, collapse or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads, including the effects of buoyancy;

Uses flood damage-resistant materials and has utility equipment which are resistant to flood damage, and also uses construction methods and practices which will minimize flood damage;

Provides in the plans part of the permit application the appropriate floodplain information including Miami-Dade County flood criteria, crown of road information, flood hazard area and base flood elevation;

Electrical, heating, ventilation, plumbing, air conditioning equipment, and other service facilities are designed and/or located to prevent water entry or accumulation; and

In nonspecial flood hazard areas, the basement:

Shall be usable solely for storage, parking, or access;

Shall not contain either main electrical or mechanical equipment; and

Require installation of sump pumps to collect and discharge the flow rate of the basement area multiplied by the rainfall intensity per hour required for the structure.

(4)

Review subdivision proposals and other proposed new developments to assure that:

All such proposals minimize flood damage;

All public utilities and facilities, such as sewer, gas, electrical, and water systems are constructed to minimize or eliminate flood damage.

(5)

Require new and replacement water supply systems and treatment plants and sanitary sewage plants and systems to be designed to minimize or eliminate infiltration of floodwaters into the systems and plants, minimize discharges from sanitary systems into floodwaters, and require on-site wastewater disposal systems to be located so as to avoid impairment of them or contamination from them during flooding.

(6)

Require a lowest floor elevation certificate or floodproofing certification, after the lowest floor is completed, and the as-built before final inspection, or in instances where the structure is subject to the regulations applicable to coastal high hazard areas, after placement of the horizontal structural members of the lowest floor. Upon placement of the lowest floor, or floodproofing by whatever construction means, or upon placement of the horizontal structural members of the lowest floor, whichever is applicable, it shall be the duty of the permit holder to submit to the city a certification of the lowest floor, floodproofed elevation, or the elevation of the lowest horizontal structural members of the lowest floor, whichever is applicable, as built and as measured in reference to NAVD 88. Said certification shall be prepared by or under the direct supervision of a registered land surveyor or professional engineer and certified by same. When floodproofing is utilized for a particular building, said certification shall be prepared by or under the direct supervision of a professional engineer or architect and certified by same. Any work undertaken prior to submission of the certification shall be at the permit holder's risk. The city shall review the floor elevation survey data submitted. Deficiencies detected by such review shall be corrected by the permit holder immediately and prior to further progressive work being permitted to proceed. Failure to submit the survey or failure to make said corrections required hereby, shall be cause to issue a stop work order for the project.

(7)

Require that all new subdivision proposals and other proposed developments include within such proposals base flood elevation data according to the city's flood insurance rate map (FIRM) information, and existing grade and crown of adjacent road elevation information according to Miami-Dade County flood criteria information.

(8)

Obtain, review and utilize any base flood elevation and floodway data available from federal, state, or other sources when base flood elevation data are not shown on the FIRM.

(9)

Review proposed development to assure that all necessary permits have been received from those governmental agencies from which approval is required by federal or state law, including Section 404 of the Federal Water Pollution Control Act amendments of 1972, 404 USC 1334.

(10)

In coastal high hazard areas, review plans for adequacy of breakaway walls in accordance with subsections 20-5(e), (f) and (g) herein.

(11)

For the purpose of this section, "base elevation" shall be defined as the elevation established by the Miami-Dade County flood criteria map, or the elevation of the crown of road or street abutting such building site, or existing and proposed grade elevations within the lot(s), whichever is higher. In cases where the base elevation fronting the land vary greater than one foot along the frontage of the lot(s), then an alternative engineered solution for flood protection may be presented to the building official or his/her designee in consultation with the director of resilience and public works.

Unless otherwise required by sections 20-4 or 20-5, for uses other than residential requiring a floor, the floor elevation shall be a minimum of four inches above the base elevation, including the entrance of a basement. For all areas that serve a residential use, including, mail rooms, lobbies and entrances to a basement, the floor elevation shall be a minimum of eight inches above the base elevation.

The provisions of this subsection shall not apply to off-street parking facilities constructed underground and other similar types of below grade areas within a building which are not lowest floor and contain neither electrical nor mechanical equipment. All such facilities constructed below grade shall be designed and constructed and contain essential equipment, if necessary, to prevent infiltration and accumulation of water or to provide for immediate and continuous elimination of water. A Florida-registered engineer or architect shall submit data and a floodproofing certificate to assure that the design complies with all guidelines of subsection 20-5(b) herein.

If in the review of a permit application it is determined that in the application of the provisions of this section the building applicant would be required to provide flood protection in excess of the requirements of this chapter, then it shall be the responsibility and authority of the building official or his/her designee to review such plans and may grant a waiver of the requirements of this section to provide flood protection which is no less than the flood protection required by this chapter based upon good engineering practice. Said decision shall be subject to appeal in accordance with subsection 20-12(i) of this chapter.

(12)

Maintain, for public inspection, in the planning, building and zoning office all records pertaining to the provisions of this chapter.

(13)

Notify adjacent communities and the Florida Division of Emergency Management prior to the alteration or relocation of a waterway.

(14)

Assure that maintenance is provided within the altered or relocated portion of said watercourse so that the flood-carrying capacity is not diminished.

(15)

Drainage systems as defined herein shall require re-certification every 120 months from the date of final inspection as set forth herein. The property owner shall be notified of the required re-certification 60 days in advance of their due date. Properties with three dwelling units or fewer are exempt from this section. Residential properties with four dwelling units or more, or where the drainage systems are comprised of five or more drainage structures on the property shall require that the drainage re-certification be completed by a registered professional engineer.

All relevant information on the existing drainage system, including, but not limited to, the approved as-built drawings and a detailed description of the existing drainage, including the intent of the system.

A site inspection of the entire drainage system to determine what, if any, maintenance and repair work is required in order to re-certify the drainage system in accordance with the following items:

Catch basin grates, manhole covers and outfalls are to be free of obstructions.

Probe catch basins for mud, debris, silt, etc. (depth of material in a pipe shall not exceed five percent of the diameter of the pipe and the depth of material in a catch basin sump shall not exceed five percent of the distance from the bottom of the structure to the lowest pipe invert).

Check headwalls for deterioration and any signs of erosion.

Check for broken grates.

Check weirs and baffles installation (12 inches minimum sump clearance from bottom of structure to bottom of baffle, if applicable).

Check for areas of sunken or deteriorated pavement which may be a sign of a drainage problem.

Check for modifications to swales and retention areas.

Check for proper maintenance of swale and retention areas.

Check for alterations to original design and construction of drainage system.

10.

Check for alterations to original design and construction of drainage system.

11.

Verify that no vegetation exists over drainage system.

All pumps shall be inspected by a registered professional engineer irrespective of property type. All drywells, including injection wells, shall be inspected by a certified well driller irrespective of property type. Pressurized system with wells and/or pumps shall be certified that it continues to function as designed and constructed. A gravity type drainage system, such as exfiltration systems shall require re-certification as per this section 1. through 11. These systems shall be required to function as designed, constructed and/or permitted. A detailed report of inspection and proper function from a registered professional engineer or certified well driller (as applicable) shall be required for re-certification.

Completion of all necessary required maintenance and/or repair work as denoted by the registered professional engineer as performed by a licensed contractor and verified by the certifying engineer.

All copies of plans and drawings, together with supporting calculations and documentation submitted must be signed, sealed, and dated by a registered professional, as required by F.S. chs. 471, 472, 481 or 492, as applicable, when the design of the system requires the services of a registered professional.

A maintenance log, if not already kept by the property owner, will be required for any future drainage re-certifications. The maintenance log shall include records related to the operation of the drainage system, including but not limited, to an estimate of the stormwater volume passing through the system in a year, dates of inspection and copies of any associated documents that evidence inspection, and dates of repairs and/or replacements of parts with type of maintenance and parts replaced, if any.

Existing drainage shall be inspected within 24 months of the adoption of this ordinance

Should property owner be unable to meet the requirements set forth in this section then an alternative engineered solution for flood protection may be presented to the building official or his/her designee in consultation with the director of resilience and public works.

Drainage systems subject to the requirements in subsection 20-3(15) of this chapter where the owner fails to timely respond to the notice of required recertification or fails to make all required repairs or modifications found to be necessary by the deadline specified in the Code or any written extension granted by the building official, or designee, shall result in enforcement as provided in chapter 2, article X of the City Code in addition to any other enforcement provided in section 20-14.

(Ord. No. 14039, § 2, 12-9-21; Ord. No. 14295, § 2, 7-11-24)