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H:\LTCANADA_CI_MN\0N1125241\1_Corres\C_To Others\City\209 Ryan Drive Memo - September 2023\209 Ryan - Update Memo.docx September 21, 2023 Honorable Mayor and City Council City of Little Canada RE: 209 Ryan Drive – Drainage Concerns Dear Honorable Mayor & City Council, The Public Works Director and I have worked with Roger Stanke, the property owner at 209 Ryan Drive for over a year regarding his drainage concerns. The intent of this short memorandum is to summarize my technical understanding of his drainage concerns both before and after improvements were made to Ryan Drive adjacent to his property. Two separate projects occurred adjacent to his property; a watershed improvement project in the fall of 2021 that raised the road approximately 3’ to accommodate a new and enlarged creek culvert, and a city-led street and utility improvement project during the summer of 2022. Mr. Stanke has been primarily concerned with the following items through the duration and completion of the two projects: 1. There is a perception that roadway water coming from the west is now being introduced to his property when it wasn’t before. 2. There is a perception that the road raising has subjected his structures to possible flooding. 3. Road raising has trapped water on his property and has led to longer durations and greater depths of standing water than before. Figure 1 – Pre-Conditions (1 of 2) As shown in Figure 1, the existing ground survey shots from before any projects were performed are depicted in red. The existing ground survey shots show that Roger’s western driveway likely took roadway drainage and that the catch basin near his eastern driveway served as the low point for the entire roadway west of the creek. Roadway water would have actually drained west from the creek to the low point and likely overflowed over the roadway to the south towards the creek during heavy rain events. Figure 2 – Pre-Conditions (2 of 2) As discussed above, the low point near Roger’s eastern driveway served as the low point for the northern half of the roadway. Figure 2 depicts what ponding would have looked like during heavier rain events when the catch basin at the low point couldn’t keep up with the water. This assumes that water crested over the roadway and headed to the creek on the south side of the roadway.