3107.1 DFEs must be identified for all development on a development site located wholly or partially inside a flood hazard area. Applicants may voluntarily design their project to be elevated or protected at a height above the DFEs required in this section.

3107.2 If an application includes a site plan, an applicant shall provide with the site plan cross sections that show the ground elevation and DFE at the site.

3107.3 Unless otherwise designated, the DFE shall be the higher of:

1. (a) The base flood elevation plus a freeboard equal to two feet (2 ft.), or
2. (b) The high flood elevation, in accordance with the most current FIS and FIRM published by FEMA and adopted by the District.

3107.4 For critical facilities permitted wholly or partially inside flood hazard areas, the DFE shall be equivalent to that identified in § 3107.3 plus two feet (2 ft.).

3107.5 For any new construction or substantial improvement located on a development site wholly or partially inside a tidal shoreline buffer area, the DFE shall be equivalent to that identified in § 3107.3 plus three and four-tenths feet (3.4 ft.).

3107.6 If the DFE is not specified on the FIS or FIRM, the applicant shall, subject to DOEE approval, either:

1. (a) Determine the DFE by obtaining, reviewing, and reasonably utilizing data available from a federal or state agency; or
2. (b) Determine the DFE by using hydrologic and hydraulic engineering techniques, and as follows:
3. (1) The determination shall be performed and sealed by a District-registered professional engineer.
4. (2) Studies, analyses, and computations shall be submitted in sufficient detail to allow review and approval by DOEE.
5. (3) The accuracy of data submitted for the determination shall be the responsibility of the applicant.

3107.7 For the Zone X (shaded) flood hazard area mapped by Letter of Map Revision (LOMR) 15-03-2388P, where no high flood elevation is specified on the FIS and

FIRM, the DFE shall be the elevation of the base flood elevation plus freeboard of two feet (2 ft.) if no high flood elevation data is available from a federal, state, or other source approved by DOEE. Requests for removal from this flood hazard area based on elevation shall be accompanied and justified by an H&H analysis that is prepared and sealed by a registered design professional and submitted to DOEE for review.

3107.8 For the Rhode Island Avenue Metro underpass area specified in § 3101.2(d), the DFE shall be the NAVD88 elevation of ninety-six and one-half feet (96.5 ft.).

SOURCE: Final Rulemaking published at 32 DCR 6547, 6559 (November 15, 1985); as amended by Notice of Final Rulemaking published at 57 DCR 10777 (November 19, 2010); as amended by Final Rulemaking published at 72 DCR 006821 (June 20, 2025).