DRUFFNER 03/08/2021 - Laserfiche WebLink

Home Browse Search

Towne, Jason From: Druffner, Jacob D - DNR <jacob.druffner@wisconsin.gov> Sent: Monday, March 8, 2021 11:23 AM To: Craig Selander Cc: Towne, Jason Subject: RE: Floodplain Questions on a Project on Yellow Lake Hi Craig, Sorry for the late response as I was trying to ensure I had my ducks in a row with the proposed project and impacts to floodplain. I have reviewed the information you have provided.To remove the land from the floodplain, 2-ft of fill will need to be placed to remove the land from the floodplain and the fill needs to be contiguous to land outside the floodplain. Additionally and prior to the fill being placed,the floodway/floodfringe needs to be delineated at the proposed project location. An engineer should make an assessment based on the existing flood insurance study(FIS) model.The modeling does not need to be re-done to do this. If the structure is in the floodway, a hydrologic and hydraulic analysis needs to be completed to assess the impacts of the fill on the regional flood elevation (RFE)as you stated. If the fill doesn't change the RFE, a letter of map revision (LOMR)would still need to be submitted for to officially remove the structure from the floodplain FEMA maps.The LOMR would be submitted for post project, in this case I HIGHLY RECOMMEND completing this after the fill is placed not after the structure is placed. FEMA will need to verify the modeling and effects on the RFE are in agreement with our approval. It may be helpful and save time and money in the long run if a CLOMR (conditional letter of map revision) is submitted before the project begins if there is or is not any change to the RFE with the proposed fill.This would pre-verify that FEMA agrees with the modeling we approve.That way the fill wouldn't need to be removed if the LOMR/modeling shows differently than we reviewed and approved. If there is an increase to the RFE a CLOMR has to be submitted for pre project. This is probably a bit confusing so please feel free to call if you have questions. Basic plan moving forward: 1. Engineer delineates floodway and floodfringe at the location of the proposal. 2. Is structure/fill to be placed is in the floodfringe, no further modeling necessary and LOMR-F process can begin. 3. If structure in the floodway, the existing FIS model needs to be used to determine impacts to RFE. Model is submitted for DNR review and approval. 4. If no impacts to RFE, I suggest submitting to FEMA for CLOMR pre-project for verification that modeling techniques and analyses are correct. Project moves forward. I would highly suggest LOMR should be submitted for after fill is placed rather than building. If mitigation is needed, this would be cheaper than altering the structure. 5. If increase in RFE, CLOMR must be submitted for pre-project and LOMR submitted within 6 months of project completion for FEMA approval. Again I suggest this being completed after fill rather than building is placed.