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September 3, 2025 Athanasia Lewis Page 2 of 3 Reference: Brian Drive Pond Water Level and Drainage Proposed Improvements: In reviewing proposed improvements, several options were considered, including draintile, retaining walls, and other piped outlet locations. Given the locations of existing storm sewer infrastructure, discussions with the property owners, and limitations with existing elevations, these options are likely not feasible and therefore have not been explored further. However, two potential options are more feasible from a constructability standpoint, and are discussed below in further detail: Option 1 Î Channel Improvements One option for consideration is improving the existing outlet channel. Providing a wider channel with a clear drainage path and a consistent slope will allow water to drain freely from the pond once it reaches the outlet elevation. Given the elevation of the existing culverts downstream of the Brian Drive Pond, we are somewhat limited in how much we can lower the outlet of the pond. Setting the outlet elevation at 903.5 will provide the recommended 2Ó of vertical separation between the outlet and the lowest adjacent floor elevation. This elevation will also allow for the outlet channel to be graded at roughly a 0.9% slope. This flatter channel will require more frequent maintenance to remove any sediment or debris that has been deposited within the channel. Regular brush removal and mowing will also be required to maintain adequate drainage. The proposed profile of the ditch improvements is shown on the attached figure. Note that the ditch will need to be lowered up to 1.4Ó in places to provide positive drainage. Option 2: Pump Station A second option for an outlet improvement would be to install a pump station at the pond and potentially downstream forcemain to regulate the water level. A pump station would allow the pond water level to be lowered more than in Option 1 (i.e. lower than 903.5). A forcemain may be required to convey the drainage to downstream outlet point. Potential outlet locations could include Clearwater Creek or some point upstream. Additional clearing and grubbing and excavation may be required depending on the chosen outlet location. One option would be to regrade the ditch as described in Option 1, and pump the pond water directly into the ditch, requiring a minimal amount of forcemain. Costs: Estimated costs for the proposed options are provided below: Option 1 Î Channel Improvements This option would involve clearing and grubbing, excavation of the existing channel (4Ó wide), and restoration. The estimated construction cost for this option is roughly $35,000 to $45,000. Option 2 Î Pump Station This option would involve clearing and grubbing, installation of a single pump and lift station structure, controls, forcemain, power source, and restoration. The estimated construction cost for this option is roughly $100,000 to $150,000. 88