"Base Flood Elevation - Zone A" Step 2: Review and Apply MDEQ Estimate
In this installment of the BMJ blog we will continue to discuss the determination of the base flood elevation (BFE) for Zone A applications.
Once the Michigan Department of Environmental Quality (MDEQ) receives a request to estimate the BFE for a particular location, staff members begin with research and calculations. The department has a large database of previous determinations that are used to typify the general geography and topography of a specific site. This database will be used along with an on-site visit to develop a conservative estimate of the BFE. This conservative estimate will most likely be higher than what the actual elevation of the BFE would be if a rigorous analysis were done based on accurate and current information.
The reason the MDEQ estimate is a conservative one is because: 1) the MDEQ does not charge a fee for the service 2) the information that they have on hand is not complete and not always accurate, and 3) to create a built-in safety factor (if you build above this elevation, then when the 1% chance storm does occur the improvements will not be affected).
Once that information is received the elevation certificate can be filled out and a comparison can be made regarding the BFE and the Lowest Adjacent Grade (LAG) of the structure. If the LAG is higher than the BFE, then the 1% chance flood event will not reach the foundation walls of the structure and therefore, in theory, not affect the structural integrity. In this scenario, the homeowner can apply to the Federal Emergency Management Agency to consider the removal of the flood insurance requirement. This would come in the form of a Letter of Map Amendment (LOMA).
On the other hand, if the BFE is higher than the LAG, the 1% chance flood event will reach the foundation of the structure and potentially affect its structural integrity which could lead to damage and a claim that would be covered by a flood insurance policy.
Remember, the MDEQ publishes a conservative estimate. It is quite likely that a more refined and in-depth analysis will result in a lower BFE. The downside to an in-depth analysis is that it will come with some additional costs. We can ask the MDEQ what information they would need to refine their original estimate. They may say something like “…provide cross section data from a professional engineer or surveyor of the flood source 500’ and 1000’ upstream and downstream of the subject location”. Armed with this data the MDEQ will revisit their initial determination and calculate a more realistic estimate. If the BFE is lowered enough the structure could qualify for a LOMA.
Next month : How to get a LOMA
