Rapid City, SD Environmental Rules: Flood Elevation Requirements (2026)
Key Facts
- Freeboard
- 1 foot above base flood elevation
- Zones covered
- A1-30, AE, AH
- AO zone standard
- Highest adjacent grade plus FIRM depth (min 2 ft)
- Certifier required
- Registered professional engineer or land surveyor
- Manufactured homes
- Also 1 foot above BFE, § 15.32.190
- Nonresidential alternative
- Floodproof watertight to 1 foot above BFE
Summary
New homes and additions in Rapid City's mapped A1-30, AE and AH flood zones must set their lowest floor, including any basement, at least 1 foot above the base flood elevation under Rapid City Municipal Code § 15.32.140. Structures in AO zones must clear the highest adjacent grade by the FIRM's listed depth, or 2 feet if none is given, and a licensed engineer or surveyor must certify the finished elevation.
A. New construction and substantial improvements of residential structures within Zones A1-30, AE or AH shall have the lowest floor (including basement) elevated 1 foot above the base flood elevation. B. New construction and substantial improvements of residential structures within AO Zone shall have the lowest floor (including basement) elevated above the highest adjacent grade at least as high as the depth number specified in feet on the FIRM (at least 2 feet if no depth number is specified). C. A registered professional engineer or land surveyor shall submit a certification to the Floodplain Administrator that the provisions of this chapter are satisfied.
Full Breakdown
140 sets Rapid City's residential freeboard standard: new construction and substantial improvements in Zones A1-30, AE or AH must have the lowest floor, including any basement, elevated 1 foot above the base flood elevation, one foot more than FEMA's bare minimum. In AO zones, the lowest floor must clear the highest adjacent grade by the depth number printed on the Flood Insurance Rate Map, or at least 2 feet if the map lists no number. A registered professional engineer or land surveyor must certify to the Floodplain Administrator that the elevation meets the chapter, and the structure cannot be used until the Administrator approves a post-construction elevation and/or floodproofing certificate.
190, which also requires a permanent, anchored foundation. 150: instead of elevating, they may be floodproofed so the structure is watertight up to 1 foot above the base flood elevation, with walls and components able to resist hydrostatic and hydrodynamic loads, certified by a registered professional engineer. 120(F)(1), and the Administrator may require it before further vertical construction proceeds.
Violations & Fines
Occupying or using a newly built or substantially improved residential structure before the Floodplain Administrator approves the post-construction elevation certificate violates § 15.32.140(D). Building below the required 1-foot freeboard, or without the engineer or surveyor certification the section requires, violates Chapter 15.32 and carries the city's general penalty under § 1.12.010: a fine of $1 to $500, up to 30 days in jail, or both, with each day counted separately.
Frequently Asked Questions
How high above the base flood elevation must I build in Rapid City?
What if my Rapid City lot is in an AO zone instead of AE?
Can I floodproof a building instead of elevating it in Rapid City?
Who has to certify my Rapid City flood elevation is correct?
Sources & Official References
Other rules in Rapid City
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