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Jul 14 2004 10:40 i/ jBonestroo &4 b Rosene wm Anderllk & Associates 6n9ln««rs ^ Architect* BONESTROO ROSENE RNDERLIK 651636131X 2335 West Highway 36 • St. Paui. MN 5513 Office: 651-636-4600 • Fax: 651-636-1311 WWW Donesiroo.com P • 1 July 14, 2004 Mike Gaffton Planning Director City of Orono Post Office Box 66 Cr>'sial Bay, MN 35323 Rc: 1925 Lakeview Terrace File No. 139-04-000 Plat No. 04-3007 Dear Mike: We have reviewed the information you provided for the vacant lot at 1925 Lakeview Terrace. The site l es within the Long Lake drainage district as identified in the City s Surface Water M^.ag^cnt Plan (SWMP). The SWMP identifies a potential ponding site (LLQ9.1) north of C.R. 6. in addition the SWMP calls for replacing the existing 15-inch culvert under Lakeview Terrace (along the north side of the subject property) shown on your Exhibit Q with a 24-inch culvert. When the culvert ii replaced the downstream invert will remain the same (1010.1) and the corresponding water elevation of a full pipe will be 1012.1. The storm water discharging from the culvert flows southerly through an existing channel along the westerly side of the subject property. The channel flows to another culvert under Country Club Road south of the site. The street elevation at the culven cressmg on Country Club Road is approximately 1010. Drainage also reaches the channel across the subject property from the east and west sides of the site in addition to the storm water discharging through the existing 15-inch culve: *. under Lakeview Terrace. With that s^d have the following comments in regards to storm water management and the buildability of the site; • The control for the elevation of the channel relative to the subject property appe;us to be the low point (1010) in the road elevation on Country Club Road south of the site. If ♦he chaimcl fills during larger storm events the road wll act as a dam and hold water back upstream until the roadway overtops at the 1010 elevation. This in effect is the emergency overflow \EOF) elevation for the area upstream, from Country Club Road. The city standard is to set the lowest floor elevations of homes adjacent to creeks or ponds at 2-fcct above the EOF. However it is possible that in larger storm events the water elevatioa discharging from the future 24-inch pipe under Lakeview Terrace could rise to an elevation of 1012.1. Based on this wc recommend the lowest floor elevation for any structure at 1925 Lakeview Terrace to be 1014. • Based on the above analysis we recommend tliai the existing easement along the channel be realigned to follow the 1012 contours adjacent to the channel. This represents the likely high water level of the channel. • Your Exhibit Q shows a strip of land along tLc west side of tV.c subject property that is separated from the buildable portion of the site by the channel. It appears this area is unbuildable duo to existing easements and setbacks. The Ci may wish to consider taking a drainage easement over this entire portion of the property to construct a smaller ponding area • St. Paul. St. Cloud, Rocheiter. Wlllmar. MN ■ Milwaukee. W! * Chicago. II____________ /iffirmitlv* Actlor/Equil Opportumty Kwpioytf and Iwpioytt Owfitd