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<br />Floodplain Alteration Rule <br />MCWD's Floodplain Alteration Rule is triggered when there is work below the 100-year flood elevation. <br />The 100-year high water elevation for Lake Minnetonka is 931.5 feet (NGVD 29). The 100-year high <br />water elevation for the tributary is unknown at this time and will need to be determined by the <br />applicant. This rule requires that compensatory storage be created to offset any proposed volume of fill. <br />The Project proposes to disturb land at or below the 100-year high-water level or proposes fill to be <br />placed below the 100-year high-water level for the placement of the northern driveway; therefore, the <br />rule is triggered. To meet MCWD’ Floodplain Alteration rule requirements, please address the following <br />items: <br />• Determine the OHW and 100-year elevations for the tributary driveway crossing. <br />• Existing conditions site plan: <br />o Existing elevation contours of the work area <br />o Ordinary high-water elevation (OHW) <br />o 100-year flood elevation <br />• Proposed site plan: <br />o Proposed elevation contours of the work area <br />o Ordinary high-water elevation (OHW) <br />o 100-year flood elevation <br />o Low openings (doors, windows, etc.) to all structures <br />• Calculation of cut and fill: <br />o Quantity of proposed cut and fill corresponding to areas of cut and fill on the site plans <br />(no net fill is allowed) <br />o Sum of proposed cut and fill between OHW and 100-year flood elevation <br />o Calculations must be signed by a professional engineer, architect, land surveyor, or <br />landscape architect <br /> <br />Waterbody Crossings and Structures: <br />MCWD’s Waterbody Crossings and Structures Rule is triggered when work is proposed within the bed or <br />bank of a waterbody. This rule requires that the proposed work maintains hydraulic capacity, <br />navigational capacity, and wildlife passage, and has no adverse impacts to water quality. To meet <br />MCWD’s Waterbody Crossings & Structures rule requirements, please address the following items: <br />• Please provide a plan set with detailed grading plans for the site, culvert/pipe <br />information and details for stormwater BMPs so they can be evaluated for compliance <br />with the water body crossings rule. <br />• Delineate full drainage area of Wetland 1 so that culverts can be sized appropriately. <br />Culverts must retain adequate hydraulic capacity. A project in a watercourse may not <br />increase upstream or downstream flood stage. <br />• Please provide documentation that the wetland/waterbody crossing is the “minimal <br />impact” solution to the specific need. The applicant must consider, as applicable, <br />rerouting to avoid a crossing or designing a crossing to avoid disturbance below top of <br />bank. Please provide at least two alternative designs that minimize or avoid the <br />proposed impact to demonstrate that the minimal impact solution is proposed. <br />Additionally, please provide an analysis, by a professional engineer or qualified <br />hydrologist, of the effect of the project on hydraulic capacity and water quality. <br />213