02-17-2004 Planning Packet - Laserfiche WebLink

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M4.2971 3210-324I Watertown Road Jaaiiary 14,2004 Pa|c3 ///. OHWL and Ftoik^flain impacts The Zoning Code defines the OHWL for watercourses as “the elevation of the lop of the bank of the channel". It also establishes the "Regulatory Flood Protection Elevation ” (RFPE) as an elevation no less than 1.0 fool above the ‘regional flood', i.e. 1' above the 100-year floodplain elevation. The Surface Water Management Plan indicates that the Normal Water Level for the large wetland basin just to the north of the property is elevation 963.5', with the High Water Level (100-year flood level) at elevation 970.4*. The top of the Hank of the channel at the constriction area in Lot 1 is at approximate elevation 968.0', and closely matches the delineated wetland boundary. In recent discussions with the City Engineer, staff has concluded that the OHWL for setback and lot area calculation purposes for this property should be established at the wetland boundary elevation of 968'. The RFPE, i.e. the minimum floor elevation for any building, should be established at elevation 971.4’, In proposed Lot 1, it appears that neither the buildable area nor the septic sites v^ill be impacted by floodplain and OHWL elevations. However, the creek driveway crossing will likely require filling within floodplain as well as wetland. /K Front Lot/Baek Lot Impacts The original subdivision was created prior to the 1994 adoption of "ftont lot/back lot" standards (Sections 78-1370 and 82-256). The existing lots aren ’t subject to these special setback and area requirements, but because new lots are being created, the subdivision will be subject to those standards. The impacts include: - Lot 1 as a back lot must meet a 3 acre minimum (it does); - Lot 1 is subject to 150% of the standard setbacks (See staff sketch. Exhibit C2). • Access to Lot I must be via a 30' driveway outlot (as proposed) - Lot 2 is subject to a 50* side street setback from the driveway outlot, rather than a 30' side setback. Summary of Regulatory Impacts I. The 968’ OHWL along the creek is the contour from which setbacks should be measured for this property. The key OHWL setbacks that affect development of the site are: - 100* stnicmre setback from OHWL • 75'septic setback from OHWL - no hardcover allowed within 75' of OHWL Areas below the OHWL will not count toward lot area calculations. The lot dry/wei areas and the OHWL setbacks as shown by the sur\ cyor appear to be accepuble.