06-09-2025 - Agenda Packet City Council - regular meeting

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From: Ronald W. Vickery, P.E. To: Melanie Curtis; Jasper, Matthew M CSM USARMY NG MNARNG (USA) Cc: Adam Edwards; Laura Oakden Subject: RE: 4745 Northshore Drive - Council Action for LA25-000007 Date: Friday, May 2, 2025 2:20:11 PM Melanie — here's the answers to your questions: 1. My landscape design was developed to directly address an ongoing erosion problem that had been affecting the stability of the shoreline and bluff line. The erosion was caused by surface water runoff, natural wave action, incorrectly installed riprap, and ice heaves which had begun to undermine the soil and vegetation near the water's edge and bluff line. To correct this, the design included erosion control measures such as deep-rooted native plants, erosion control fabric, and slope stabilization techniques with the staircase and boulder retaining walls. These improvements were intended to stop further erosion, help restore the health of the shoreline and preserve the roots of trees that are exposed. 2. When I began working with the property owner and the contractors, Matt's main goal for this project was to correct the shoreline with a 3:1 slope with large rip rap toe boulders, construct a safe stairway to the lake shore that would also help in stabilizing the bluff side, and protect as many trees as possible. Given the condition of the bluff line, it was evident that it had not been previously addressed properly. The results of my global stability analysis indicated an overall global stability factor of safety of 1.378, which is in excess of the industry standard factor of safety of 1.3. Please note, without the retaining walls, this factor of safety would be less than 1.3. Therefore, the retaining walls and the stair system will greatly aid in the stabilization of the slope. 3. 1 am a registered professional engineer in the state of Minnesota (among others), and have been designing retaining walls for 27 years. I've been running my own company, Vickery Engineering & Consulting, LLC, since 2007. 4. The landscaping was carefully planned to be as minimal and natural -looking as possible. It includes only what is necessary to stabilize the shoreline and bluff line to prevent further erosion. Native plants were chosen not only for their effectiveness in holding soil in place but also for their ability to blend into the natural surroundings. Less than 4' tall boulder walls were used in areas where native plants would not have been enough to prevent further erosion. With Matt's goal to preserve as many trees as he could on the hill side, small boulder walls was the only way properly accomplish that. No unnecessary structures were made to the landscape, and every effort was taken to preserve the natural view and character of the lakeshore. I hope this helps. Please let me know if you have questions or need anything else. Thanks, Ronald W. Vickery, PE Vickery Engineering & Consulting, LLC Post Office Box 86 Grandy, MN 55029 Phone: 952-465-8272 www.vickeryeng.com Engineering Solutions for an Unstable World- 221