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Zoning File #1904 May 9, 1994 Page 2 of 3 this met with the approval of the City of Orono. Planning Commission members should be aware that it is the responsibility of the City of Orono to enforce all Federal flood plain regulations. The Watershed District also reviews and issues permits for any activity that involves the alteration of the flood plain of Lake Minnetonka. The City has reviewed the applicants' plan of mitigation proposing the excavation of some 630 cubic feet to the south or street side of the property. The proposal involves the excavation of approximately 6" over a 36' x 35' area. To qualify for flood plain storage, the excavation would have to take place below the 931.5' elevation and above the 929.4' OHWL of Lake Minnetonka. As Gustafson's comments note (Exhibit H), the total excavation would result in a retention pond at a 2' depth as credit would only begin once you reach the 931.5' elevation Gustafson recommends a shallow trench or swale be excavated out to the lake along the side, preferably the west side of the property as the east side contains more mature planting. He notes that, based on the review of topographic information, excavations within this area of the property would be located within the flood plain and qualify. The drainage swale would also provide positive drainage from the residence. In fact during the Planning Commission's review of this application (review Exhibit D), applicants advised that it was their plan to create drainage swales to carry runoff to the lake. In further discussions with Gustafson, we concurred that applicants should provide additional grading and drainage plans with the submission of the building permit confirming the location and width of the swale noting that swale need not go any further south from the lake than to the low retention area adjacent to residence and that spot elevations be shown within swale confirming positive drainage to lake. Once again, mitigation credit can only be gained by excavations between the 929.4' and 931.5' elevations. The MCWD has also asked that the regulatory flood protection elevation be set at 933.5' rather than 932.5' as required per Orono Municipal Ordinance Section 10.55, Subdivision 7 (B). The Watershed District requires 2' above the flood plain elevation at 931.5'. Staff Recommendation To approve the conditional use permit and variance for Eric and Shelly Liljequist that would allow the filling and compensatory mitigation of 625 cubic feet within the flood plain of Lake Minnetonka, based on the following findings: 1. Proposed improvements will not increase the runoff on the property. 2. The required swale will provide positive drainage on the property. 3. A permanent residence has existed on the property for over 50 years.