10-12-2022 Council Packet - Laserfiche WebLink

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Prepared by: Bolton & Menk, Inc. Proposed Improvements Twin Lake Boulevard ǀ 0N1.125376 Page 7 SANITARY SEWER The sanitary sewer network is in good condition and is proposed to be left in place. Each of the sanitary sewer manholes in the pavement will receive a new casting and will be adjusted to the new pavement elevation. This typically involves removing the casting, covering the structure until after the base course is paved, and installing the casting on new rings with a new I/I barrier. Benches and inverts that have deteriorated will receive mud work. Phase 2 (west parcel) of the proposed multi-family development sits lower than the adjacent sanitary sewer in Twin Lake Boulevard. As such, the development will likely need a private lift station and forcemain to lift the sewage to the gravity system. The developer’s engineer has also been vetting the possibility of extending gravity sewer into the City of Vadnais Heights; this would come at a higher upfront cost to the development but would reduce long-term maintenance costs and risks. Project staff from each City will continue to work with the developer’s engineer and coordinate any possible sanitary sewer improvements along Twin Lake Boulevard with the project. Refer to Figure 3 in Appendix A for a depiction of the proposed sanitary sewer improvements. WATER MAIN The existing ductile iron watermain is in good condition and is proposed to be left in place. Existing water services are also proposed to be left in place. Approximately 400’ separates the City of Little Canada watermain system from the City of Vadnais Heights watermain system. Staff from each City has expressed a desire to connect the two systems on an ‘emergency interconnect’ basis. Connecting the two systems provides long-term options for shared water in cases of emergency. Valves are proposed on each end of the interconnect with each valve remaining closed unless both cities elect to open under the emergency-use scenario. Cost participation and expectations for long-term use are detailed in the cooperative agreement in Appendix F. Refer to Figure 3 in Appendix A for a depiction of the proposed watermain improvements. STORM SEWER The existing storm sewer structures near the low point along Five Star Estates are proposed to be replaced due to their poor condition and the magnitude of severity that would result if they failed during a rain event. Additional storm sewer improvements are proposed as a result of proposed trail improvements. Those storm sewer improvements are outlined and tabulated within the Trail sections of this report. Refer to Figure 3 in Appendix A for a depiction of the proposed storm sewer improvements. PEDESTRIAN AMENITIES An 8’ wide bituminous pedestrian trail is proposed along the north side of Twin Lake Boulevard from Vadnais Boulevard to Vadnais Boulevard. This pedestrian amenity would connect to a future regional trail that is being planned by Ramsey County. The location of the pedestrian trail relative to the roadway will vary throughout the length of the roadway. Where space is constrained, the trail will be located immediately behind the roadway with B618 concrete curb and gutter acting as a buffer between the roadway and the trail. In other locations, the trail will be separated from the roadway to better fit the existing topography, existing drainage patterns, and to reduce overall impacts to properties and existing vegetation. An existing wetland was delineated along the west end of Twin Lake Boulevard. Final trail design should performed such that impacts to the existing wetland are avoided to the extent possible. This may result