Agenda - Public Works Committee - 03/20/2012

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Outlet Pipe Size 100 -Year 100 -Year Estimated Cost Outlet Pipe HWL HWL N/A Size (658W) (659W) Estimated Cost Existing 862.1 860.4 N/A Existing + 15" 861.8 861.2 $15,290 Existing + 18" 86L7 861.3 $18,755 Existing + 24" 861.6 861.4 $29,040 Outlet Pipe Size 100 -Year HWL (658W) loo -Year HWL (659W) Estimated Cost Existing 862.1 860.4 N/A Existing + lower 18" 861.6 861.3 $18,755 Existing + lower 24" 861.6 861.5 $29,040 Tables 9 through 11 include the individual costs for this alternative. As mentioned above, it is our understanding that any work proposed below an elevation of 860 will need the approval of the DNR. This alternative will not have any effect below an elevation of 860 and is not anticipated to need the approval of the DNR. Removing the weir structure and constructing a culvert under TH 47 will require MnIDOT's approval. Alternative 3 Alternative 3 will include removing the existing weir structure and constructing an additional outlet from DNR Wetland 658W under TH 47. The proposed additional outlet would be at an elevation of 859.0, one foot lower than the existing outlet. It was assumed the additional pipe would have to be jacked under TH 47. Two different sized additional outlet pipes were analyzed. The following table summarizes the 100 -year HWL's for DNR Wetlands 658W and 659W and the estimated costs to construct each outlet pipe: Tables 12 and 13 include the individual costs for this alternative. As mentioned above, it is our understanding that any work proposed below an elevation of 860 will need the approval of the DNR. This alternative has work proposed below an elevation of 860 and will need the approval of the DNR. Removing-the weir structure and constructing a culvert under Trunk Highway 47 will require MnIDOT's approval.