Section 20-3105. TECHNICAL PROVISIONS

 

3105.1In order to prevent excessive damage to buildings and structures due to flooding, the provisions of this section shall apply to all proposed construction or development occurring in any SFHA.

 

3105.2Within SFHAs, the lowest floor (including basement) of any new construction of, or substantial improvement to, residential structures shall be at least one and one-half feet (1-1/2 ft.) above the base flood elevation and shall be verified by an Elevation Certificate (FEMA Form 81-31) or its latest available version from www.fema.gov.

 

3105.3Within SFHAs, the lowest floor (including basement) of any new construction of, or substantial improvement to, non-residential structures shall be at least one and one-half feet (1-1/2 ft.) above the base flood elevation or be designed and constructed to be floodproofed during any flood up to that height. Elevation and floodproofing shall be verified by an Elevation Certificate (FEMA Form 81-31) and a Floodproofing Certificate (FEMA 81-65), or their latest available versions from www.fema.gov.

 

3105.4 For any new construction of, or substantial improvement to, non-residential structures within SFHAs, enclosed space below the lowest floor (including basement) which will be used solely for the parking of a vehicle, building access, or incidental storage in an area other than a basement, shall be designed and constructed to allow for the automatic entry and exit of flood waters for the purpose of equalizing hydrostatic forces on exterior walls.

 

Designs shall be certified by a District registered professional engineer or architect that designs are in accordance with ASCE 24 publication (Flood Resistant Design and Construction) or shall meet or exceed the following minimum criteria:

 

(a) A minimum of two (2) openings having a net total area of not less than one square inch (1 in.2) for every square foot (1 ft.2) of enclosed space; 

 

(b) The bottom of all openings shall be no higher than one foot (1 ft.) above grade; and

 

(c) Openings may be equipped with screens, louvers, or other coverings or devices provided that they permit the automatic entry and exit of floodwaters.  

 

3105.5Any non-residential structure, or part thereof, which will not be completely or adequately elevated, shall be designed and constructed to be floodproofed in accordance with the standards contained in the publication entitled “Non-Residential Floodproofing – Requirements and Certification (Technical Bulletin 3-93)” or its latest available version by FEMA from www.fema.gov, or some other equivalent standard for that type of construction. Designs shall be certified by a District registered professional engineer or architect, and floodproofing shall be verified by a Floodproofing Certificate (FEMA 81-65) or its latest available version from www.fema.gov.

 

3105.6The following minimum standards shall apply for all new construction or development proposed to be undertaken within any SFHA:

 

(a) If fill is used, it shall:

 

(1) Extend laterally at least fifteen feet (15 ft.) beyond the building line from all points;

 

(2) Consist of soil or small rock materials only. Sanitary landfills shall not be permitted;

 

(3) Be compacted to provide the necessary permeability and resistance to erosion, scouring, or settling;

 

(4) Be no steeper than one (1) vertical to two (2) horizontal, unless substantial data, justifying steeper slopes are submitted to, and approved by DCRA; and

 

(5) Be used only to the extent that it does not adversely affect adjacent properties;

 

(b) Storm drainage systems shall:

 

(1) Be designed to convey the flow of stormwater run-off in a safe and an efficient manner; 

 

(2)Ensure proper drainage along streets, and provide positive drainage away from buildings.

 

(3)Be designed to prevent the discharge of excess run-off onto adjacent properties and maintain the rate of stormwater run-off at pre-construction or development rates;

 

(c) Water and sanitary sewer facilities and systems shall be designed as follows:

 

(1) All new or replacement water and sanitary facilities and systems shall be designed in accordance with ASCE 24 publication (Flood Resistant Design and Construction), and located and constructed to minimize or eliminate flood damage and the infiltration of flood waters;

 

(2) Sanitary sewer facilities and systems shall be designed in accordance with ASCE 24 publication (Flood Resistant Design and Construction) to prevent the discharge of untreated sewage into flood waters; and

 

(3) No part of any on-site sewage system, and waste disposal system shall be located within any SFHA except in strict compliance with all local regulations for such systems. If any such system is permitted, it shall be located so as to avoid impairment to it, or contamination from it, during a flood;

 

(d) All gas lines, electrical, meters, transformers, generators, and telephone systems, and utilities other than water and sanitary sewer systems, shall be located, elevated (wherever possible), and constructed to minimize the chance of impairment during a flood;

 

(e) The finished elevation of all new streets shall be no more than one foot (1 ft.) below the regulatory flood elevation, and meet the requirements of the District’s water pollution control regulations (20 DCMR §§ 500, et seq.);

 

(f) The storage of any and all materials that may affect the base flood elevation or the floodway, and which are not listed in § 3106.2, shall be stored at or above the Regulatory Flood Elevation, or else be anchored and floodproofed to the maximum extent possible;

 

(g) All buildings and structures shall be designed, located, and constructed so as to offer the minimum obstruction to the flow of water and shall be designed to have a minimum effect upon the flow and height of flood water;

 

(h) Anchoring shall be used as follows:

 

(1) All buildings and structures shall be firmly anchored in accordance with accepted engineering practices to prevent flotation, collapse, or lateral movement; and

 

(2) All air ducts, large pipes, storage tanks, and other similar objects or components located below the regulatory flood elevation shall be securely anchored or affixed to prevent flotation;

 

(i) Floors, walls, and ceilings shall be designed as follows:

 

(1) Wood flooring used at or below the regulatory flood elevation shall be installed to accommodate a lateral expansion of the floor, perpendicular to the flowing grain without causing structural damage to the building;

 

(2) Plywood used at or below the regulatory flood elevation shall be of a "marine" or "water resistant" variety;

 

(3) Walls and ceilings at or below the regulatory flood elevation shall be designed and constructed of materials that are water resistant and will withstand flooding;

 

(4) Windows, doors, and other components at or below the regulatory flood elevation shall be made of metal or other water resistant material; and

 

(5)Wood fasteners used at or below the regulatory flood elevation shall be of a corrosive resistant type (such as hot dipped galvanized or stainless steel);

 

(j)  Paints and adhesives shall be used as follows:

 

(1) Paints or other finishes used at or below the regulatory flood elevation shall be of a "marine" or "water resistant" quality;

 

(2) Adhesives used at or below the regulatory flood elevation shall be of a "marine" or “water resistant” quality; and

 

(3) All wooden components (such as doors, trim, and cabinets shall be finished with a "marine" or “water resistant” paint or other finishing material;

 

(k) Electrical distribution panels shall be at least three feet (3 ft.) above the base flood elevation. Separate electrical circuits shall serve lower levels and shall be dropped from above;

 

(l) Water heaters, furnaces, air conditioning and ventilating units, and other electrical, mechanical, or utility equipment or apparatuses shall not be located below the regulatory flood elevation; and

 

(m) All gas and oil supply systems shall be designed to prevent the infiltration of flood waters into the system and discharges from the system into the flood waters. Additional provisions shall be made for drainage of these systems in the event that flood water infiltration occurs.

 

3105.7Within any floodway as designated in the FIRM, no development which would result in any increase in the base flood elevation shall be permitted unless the increase in flood elevation is fully offset by stream or channel improvements which have been approved by the Department. 

 

3105.8 Within any SFHA without a floodway, no new construction or development shall be allowed unless it is demonstrated to the satisfaction of the Department that the cumulative effect of the proposed development, when combined with all other existing and anticipated development, will not increase the base flood elevation more than one foot (1 ft.) at any point.

 

authority

The Acting Director of the District Department of the Environment (the Department, or DDOE), in accordance with the authority set forth in the District Department of the Environment Establishment Act of 2005, effective February 15, 2006 (D.C. Law 16-51; D.C. Official Code § 8-151.01 et seq.), the Water Pollution Control Act of 1984, as amended, effective March 16, 1985 (D.C. Law 5-188; D.C. Official Code § 8-103.01, et seq.), the Soil Erosion and Sedimentation Control Act of 1977 (D.C. Law 2-23; codified at Chapter 21 of District of Columbia Municipal Regulations (DCMR), §§ 500 through 507), the District of Columbia Applications Insurance Implementation Act, (District of Columbia Law 1-64, D.C. Official Code § 6-501, et seq.), and Mayor’s Order 2006-61, dated June 14, 2006.

source

Final Rulemaking published at 32 DCR 6547, 6554 (November 15, 1985); as amended by Notice of Final Rulemaking published at 57 DCR 10772 (November 19, 2010).

EditorNote

20 DCMR 3105 is formerly entitled, "Special Provisions."