02-16-2010 Planning Commission Packet

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/��'�� !�` MEMORANDUM To: Melanie Curtis Planning Co�ission From: Mike Gaffron, Asst. City Admin. - Long Term Strategy Date: February 16, 2010 Subject: #10-3446 re: Section 82-2: Definition of Dry Buildable Land Since adoption of new subdivision ordinances in 1984 the Orono Subdivision Code has defined "Dry Buildable Land" as land occurring within the properry lines of a parcel or lot, excluding drainageways, flowage areas, floodplains, wetlands, marshland or slopes of 18 percent or greater. In practice, portions of this definition have been consistently strictly adhered to while others have been invoked only in extreme circumstances. For example, wetlands and drainageways, including stormwater ponding areas, have always been excluded from the calculable lot area; while floodplain areas adjacent to the shores of Lake Minnetonka (land between the 929.4' OHW and the 931.5' floodplain elevation) have in many cases not been excluded. Likewise, slopes exceeding 18% occurring on limited or non-continuous portions of lots within subdivisions have generally not been excluded, and most walkout lots have some portion of the site having slopes exceedin� 18%. The 18% slope exclusion becomes more critical as the length and steepness of slope increases. In fact, the Bluff definitions added to the Shoreland ordinances in 1992 use >30% to define bluff slopes but also rely on the transition between slopes greater than 18% and slopes less than 18% to define the `top' and `toe' of a bluff. Because structures are prohibited in the areas defined as `bluff impact zones' (the bluff itself and land within 20' of the top of the bluf�, it can be araued that such areas by definition in the Shoreland axe not `buildable' and should automatically be excluded from the calculation of buildable area. Regarding application #10-3446, proposed Lots 4-5-6 each contain substantial areas defined as bluff; on Lot 5, more than half the lot area is bluff, and the bluff in these areas has slopes in the range of 50%-70%. And in the case of this subdivision, the bluffs are part of a major ravine, subject to erosion, that outlets near Forest Lake. These are extreme and unusual circumstances unique to this property and not found in a majority of other subdivisions the City has processed in contemporary times. It would not be unreasonable to exclude the area of the bluffs from the dry buildable area attributable to this proposed subdivision.