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Name: Mayor and City Council Date: September 21, 2023 Page: 2 H:\LTCANADA_CI_MN\0N1125241\1_Corres\C_To Others\City\209 Ryan Drive Memo - September 2023\209 Ryan - Update Memo.docx Figure 3 – Current-Conditions Figure 3 depicts the state of the roadway as it exists today. The roadway was raised during the watershed project and in turn the driveway approaches were steepened to accommodate the higher roadway. Catch basins were added to the existing underground storm sewer system to collect the water between Roger’s two driveways. Based on general discussions with Roger it seems the underground piping is undersized and cannot keep up during peak rain events and the water starts to pool. The area shown in blue depicts the likely ponding before water can escape to the creek. The underground storm sewer likely couldn’t keep up in the ‘pre’ condition which would have led to water cresting over the roadway. The eastern edge of his eastern driveway now serves as the emergency overflow or crest-point and holds water back to a higher elevation than before (by around 4”). This leads to deeper ponding until the undersized storm sewer can eventually discharge the water to the creek. The overflow point is still more than 1.0’ lower than the lowest building corner. Figure 4 – Proposed Solution - Lower Eastern Driveway Figure 4 depicts a solution that we discussed with Roger the week of August 21st. Roger described that the eastern driveway was paved too high and that it holds water back when the underground piping cannot keep up with flows. Upon further investigation it appears that this concern is valid and that lowering the eastern driveway would reduce the depth of ponding in his property by about 4”. Some ponding would still occur near the western driveway until the water can eventually make its way through the underground storm sewer piping. Figure 5 – Roger’s Request – Place Berm Across Western Driveway Figure 5 depicts Roger’s request to place a bituminous curb or berm across his western driveway. He feels that a curb, if started from his neighbor’s driveway, would prevent water from coming down his western driveway and filling his property with water. As shown in Figure 1, roadway water already entered his property via the western driveway before any work was performed. As shown in Figure 5, a curb or berm across Roger’s west driveway would result in ponding in the street before the water ultimately made its way back into Roger’s property when the curb ends. In the event Roger desires curb all the way to his eastern driveway, water would collect in the roadway and Roger’s on-site ponding would not be improved. As shown in Figure 6 below, the drainage being conveyed towards Roger’s property is much broader than just drainage coming from the roadway. Based on this analysis, a curb would negatively impact the safety of the roadway while not improving the ponding issues within Roger’s property and is not recommended.