As a commercial GC, I've built many projects in the 100 year flood plain for clients. As an aspiring commercial developer, I tend to look at properties that I believe are GREAT opportunities based on location and price per acre/foot that fall in these flood zones. Aside from additional detention volume, mitigation, and raising the elevation, what are some other factors I may need to consider that are more technical than moving dirt.
I always plan on engaging with a civil engineer during the due diligence phase so I will know if a property will be suitable for my proposed development.
Developer · San Antonio · Member since 2016 · 157 posts · 85 votes
1y
The impact of additional design effort & permitting to the timeline of the project. Modeling the floodplain can be significant work for the civil, and then permitting time with FEMA can be extensive.
@Brent Thomas The current cost of flood insurance for a building in a flood plain may need to be considered.
I just looked at a 4 plex in a flood plain. The homeowners insurance was about $2500 but the flood policy was $10,000.
This alone was enough to deter me from any further consideration of this property as without factoring in any other information $1000+ per month in insurance ate up any cash flow that there might be otherwise.
Developer · Member since 2020 · 4k+ posts · 4k+ votes
1y
OP not sure on what you mean by more technical.
1. Keeping water flow into the downstream neighbors property the same.
2. Do you create a damming effect causing a portion of a neighbors property to now be in a flood zone.
3. Sewage lift pump. Do you have enough “fall” across your property, or do you need a lift pump.
4. Storm drains. Do you have enough “fall” to connect to the city or reach a storm pond.
5. Surface coverage versus drainage. Example. If you have say 80% building coverage that drains onto a drive say 5%, it will flood your building. Grew up in LA and TX. The most unexpected place I saw this was Lubbock TX. The town would flood because it was so flat and had to much building coverage for the drainage.