Agenda Packets - 2021/07/06 - Laserfiche WebLink

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on recent Barr sediment sampling of stonriwater ponds in ether local municipalities. Additional preparation costs are associated with collecting sediment cores. A sampling plan will need to be created to dune the locations of the cores, the required depth of the cores, and material sampling intervals; and a watershed review will need to be conducted to determine historic land uses. These preparation costs are not included in the $4,000 per sample planning -level cost estimate above. 2.10 Assessment of Stormwater Pond Expansion The stortnwater pond expansion assessment considered several factors including the degree of sedimentation found for the pond, its wetland characterization, the potential water quality benefits of increasing the permanent pool volume, and proximity to other waters. luring our survey of the pond, our review included looking for other maintenance needs (i.e.. erosion, structure deterioration, excessive or undesired vegetation growth, etc.). Items identified that require general maintenance are described in Section 3 of this report. Such general maintenance needs typically require a more immediate response, and are usually included in ongoing maintenance programs as opposed to being included in a pond expansion or modification plan. This is because it may make more sense to correct a pipe, structure deterioration problem, or an erosion problem ahead of performing other major, but not urgent, pond maintenance activities. 2.11 Planning Level Cost Estimation The cost of expanding the current permanent pool volume for storinwater ponds greatly depends on the amount of material to be removed and the required method of material disposal, which is based on the chemical constituents of the pond sediments. The disposal costs, as well as the costs associated with excavation, loading, and short -distance hauling were included in a cost estimate of pond maintenance for Silver View Pond depending on the level of contamination found in the sediment. As sediment cores were not collected as part of this phase of the assessment process, three costs, one representing each management level for materials, were used to prepare a possible range of costs fir planning and budgeting purposes. The cost estimate does not take into account additional casts for wetland permitting/mitigation, permitting associated with the disposal of contaminated material, engineering and design costs, or costs for easements. These additional project costs could easily equal the cost of the sediment removal, effectively doubling the cost of the project. V- Mpls 21 Mk 62 2tt" I082 Silver Vie" Pond Assetii;mvni World ilec kepori tiihci View fond Assncsti%cnl-rinal.doc% 10