06/27/2007 Env Bd Packet - Laserfiche WebLink

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a setback of 50 % of the structure setback. This is the closest distance that a structure may be built in a shoreland district. The removal of vegetation is also prohibited in a shore Impact Zone at half the distance from the OHW to the back of proposed structures. Conservation Easement Recommended As an additional AUAR recommendation, a conservation easement containing no -mow, dumping, cutting, building in, or filling in, and naming the City as the easement holder with the right to perform restoration work in the easement. This easement should be written from the wetland edge. Surface Water Management Stormwater Management Areas (SMA's) are designed in the AUAR to support large infiltrating surfaces or wetland complexes. To create conditions appropriate for these two types of stormwater management features, SMA's within the AUAR must have: • No more than 20% of their surface as permanent open water; the remaining surface area of each SMA shall contain mesic prairie or wet prairie communities to maximize the infiltration and water quality treatment capacities of the system • Design high water levels (100 -year) less than or equal to 2.5 feet above the normal water level or lowest outlet invert • Side slopes that are less than or equal to 6:1. Horizontal to vertical and 10:1 safety bench at the normal water level per RCWD requirements. Post development runoff release volumes should be no less than 80% and no greater than 150% of existing conditions runoff volumes. These standards must be verified by our City Engineer. The Moon Acres Stormwater Management Area is an isolated 7 acre, free - outfall area that crosses the Moon Acres property line to the east. This is in a type A soil category; that is, the soils have rapid permeability and low potential for runoff. This area requires a 0 -5% area for detention. The development acreage on the Wessel property needing to meet the AUAR volume requirements is .28 acres in the .65 acre development unit. The volume needed for retention, and the retention /infiltration features proposed, must be verified by our City Engineer to conform to the AUAR standards. Rice Creek watershed District issued a Conditional approval pending receipt of changes (CAPROC).(Attachment 8). Issues include: • Geotechnical soil borings at proposed BMP location in order to determine depth to the water table. This is important in that the designer is calling these infiltration ponds. Infiltration ponds designed • • •