Zoning Practice — April 2012
Ask the Author
Here are reader questions answered by Terri Turner, AICP, author of the April 2012 Zoning Practice article "Promoting Flood Resiliency Through the Regulatory Process."
Question from Bill Veno, AICP, Martha's Vineyard Planning Commission:
I wonder about elevating new or reconstructed structures in an already commercially developed strip that is entirely within the floodplain. Besides increasing accessibility hurdles, it creates a rather unusual streetscape and creates a disincentive to make structural improvements. We recently required a new structure to be elevated a couple of feet above the other structures within a commercial property that has several other 15–20 year old buildings, which the owner thought diminished the continuity of his buildings.
- Do some communities employ thresholds for evaluating when to require elevating new construction (square footage, lot coverage, relationship to adjacent structures/uses)?
- I'm also interested in the arguments for being firm in adhering to floodplain protection measures.
Answer from author Terri Turner, AICP:
Although elevation is generally my (personal) preferred option in dealing with structural safety in relation to flood resiliency, a very workable alternative for commercial structures is floodproofing. As defined by FEMA, "The NFIP allows a new or substantially improved non-residential building in an A Zone (Zone A, AE, A1-30, AR, AO or AH) to have a lowest floor below the Base Flood Elevation (BFE), provided that the design and methods of construction have been certified by a registered professional engineer or architect as being dry floodproofed in accordance with established criteria. Floodproofing is not permitted in Coastal High Hazard Areas (Zone V, VE, or V1-30)."
Requirements and Certification for Non-Residential Floodproofing can be found at the FEMA website at http://www.fema.gov/library/viewRecord.do?id=1716. This document provides guidance on the NFIP regulations concerning watertight construction and the accompanying certification required for floodproofed non-residential buildings.
It is important to note here that FEMA recommends that "floodproofing be implemented up to one foot above BFE for a factor of safety and to receive full credit for flood insurance rating."
Floodproofing will also address the community's freeboard (a factor of safety usually expressed in feet above the BFE for purposes of floodplain management) requirements, if there are any.
On the subject of freeboard, many communities generally include at least one foot of freeboard in their floodplain management requirements "to account for the one-foot rise built into the concept of designating a floodway and the encroachment requirements where floodways have not been designated" according to FEMA. Freeboard can also account for unknown factors within the community (or within that particular watershed) that could increase flood heights to greater than those flood heights shown on the community's Flood Insurance Rate Map (FIRM). These factors include new development in vulnerable areas and the impacts of climate change, such as an increase in the frequency, magnitude, and severity of storm events and, along the coast, sea level rise.
Our local community, here in Augusta, GA, has a 3 foot freeboard requirement—two feet higher than what the State of Georgia requires and a foot higher than the freeboard requirement we had within the community until mid-2000. It is important to note here that every inch/foot of freeboard required by the community significantly reduces flood insurance rates on the structure, but more importantly, significantly reduces the flood risk on the structure and its occupants.
To answer your last question about standing firm, I could literally write a book here (but I won't). Let's start out with "it's just the right thing to do." Would your community consider not adhering to the building code, to the fire code, or to the public safety code? What makes the Floodplain Protection Measures within your community any less necessary and vital? Floodplain protection measures are in place to protect property and people from harm during flood events, short and simple.
We could follow that argument up with the legal liability your community may suffer if you don't adhere to your own floodplain protection requirements (or if you don't adequately enforce those same requirements), or, worse yet, if you knowingly permit development that results in, or increases damages to, other property owners. Because damages are so easy to predict now with advanced hydraulic and hydrologic modeling, communities are most likely to be successfully sued NOT when they deny a permit to construct a development but when they approve a permit to construct that causes damages to others.
Finally, we could end the argument with a phrase I have used time and time again, in my writings and it drives to the very center of whether or not a community should stand its ground: "The loss of even one life is much too high a cost to pay."