Agenda Packets - 2009/02/08 - Laserfiche WebLink

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February 9, 2009 Item No. 11B 1 Page 4 x Option 2 – Raise the Trail to Prevent Overtopping If the predicted overtopping of the trail is considered to be unacceptable, then the design elevation of the trail could be raised such that the trail would be above the predicted high water level of the pond. To raise the trail, fill would need to be added to the berm. The top of the berm would need to be maintained wide enough to support the proposed trail. Therefore, the added fill would result in extending the slope limits on either side of the berm, increasing the construction area of the project. Wetlands are present in this area, having been delineated on both the ditch and pond sides of the berm. The trail as currently proposed does have a small impact on the wetlands – approximately 610 SF total. Figure 2 included with this Staff Report shows the locations of the existing delineated wetlands, and the wetland impacts caused by the trail as currently designed. The proposed wetland impacts have been reviewed and accepted by both the Corps of Engineers and RCWD through the permit processes. To mitigate for the wetland impacts, the City would be purchasing credits from the Minnesota Wetland Bank. With the increased slope limits caused by adding fill to the berm to raise the trail, the amount of the wetland impacts would be increased. This would require that additional credits be purchased by the City from the Wetland Bank. More significantly, it would require that the documentation regarding the wetland impacts be revised and resubmitted to the Corps of Engineer and RCWD for consideration of amending the previous approval. If the trail is raised, added project construction costs would be incurred to add the fill material, and additional engineering expense would be incurred to revise the plans and to prepare and submit the revised permit materials regarding the wetland impact. In addition to the expense, there would be a time delay to the project caused by the review of the permit amendments. Such delay is estimated to be approximately one month. The current project schedule had construction of the project beginning approximately June 1, 2009, and being completed in early September. If the project were delayed for additional permit review, the schedule would be pushed back to start in early July and be completed by early to mid October. This would still be feasible. A summary of these Options is shown in the table on the following page.