Wendy Colsen

Page 1

January 28, 2025 Wendy Colsen 208 N. Maple Street Saugatuck, MI 49453 Re:

208 N. Maple Street Drainage Issues

Ms. Wendy Colsen: We had the opportunity to attend the City Council workshop on 01/22/2025 to listen to a discussion regarding the drainage issues that have been ongoing at your property at 208 N. Maple Street for the last 10+ years. After hearing the presentation from Fleis & Vandenbrink, it appears that the current solution being proposed is to install underground detention upstream of, and in close proximity to your property. This solution closely aligns with our original recommendations as provided in a letter dated Jan 05, 2022. To re-iterate, the erosion problems being experienced are the result of street improvement projects completed ‘up-stream’ of your property which have resulted in decreasing the time of concentration, or the time it takes water to reach the drainage course through your yard. The changes have resulted in higher volumes of water reaching the drain and at higher velocities than were experienced prior to this work. Stormwater detention is one of the most effective ways to decrease flows to this drainage course and decrease the water velocity which will create less erosion in this receiving drainage course. As there are also significant projects planned to improve water and sewer infrastructure in the area, the construction of stormwater improvements also have the added benefit of being less costly to build now than as a standalone project at a future date. Pay items such as contractor mobilization, road demolition, road repair etc. can be shared between infrastructure projects rather than just included on the stormwater project. In summary, we believe the detention system will have a lasting, positive impact on your property. However, it should be noted that the system will have a design storm. This storm will likely be a 25-year event. The proposed system will provide benefit for all events below the design storm, but for events larger than the design storm the system will be designed to overflow and route the water to the existing drainage course. In our previous report we mentioned that a combination of underground detention and a flood event bypass pipe would be the most effective solution in the long term and provide benefits for all storm events. That recommendation remains unchanged and the original exhibit showing underground detention along with a 250’ bypass pipe to the existing country drain just north of your property has been reposted here for reference. Again, we appreciate your reaching out to us to provide insight into this issue and look forward to assisting as you work with the appropriate agencies to implement a solution. Sincerely,

Brandon Simon, P.E. Progressive AE BS P:\94970001\03 WIP\C3 DISCIPLINE\Civ\Drainge Study Response.docx

Page 2

Proposed Infrastructure Improvements to Reduce Erosion