comments from city engineer and attorney on proposed house

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. � ` r , 2335 Highway 36 W St.Paul,MN 55113 Te1651-636-4600 Fax 651-636-1311 www.bonestroo.com luly 16, zoo� �Bonestroo Mr. Bruce Vang Building Official City of Orono Post Office Box 66 Crystal Bay, MN 55323 Re: 2690 Fox Street File No. 000139-07000-1 Plat No. 07-A11097 Dear Bruce: We have reviewed the Grading Plan for the proposed house at 2690 Fox Street, dated 7-12-07. We have the following comments with regards to engineering matters: • The revised plan shows a rain garden at the east edge of the lot. It is our understanding that this will receive approximately half of the house run off and as much of the driveway as possible. This design is fully acceptable. • With our field inspection on 7-12-07, we located a drainage pipe that runs from the northwest corner of the property to and ties into the existing catch basing shown just east of the proposed driveway. This pipe must continue to function during and after the house construction. • If the proposed home foundation or associated grading damages or exposes the existing pipe, a solution to this situation must be approved by the city. This may require installing a new storm sewer and catch basins that connect to the existing pipe from the northwest, installing catch basins in the yard, and connecting the proposed driveway culvert to the existing catch basin. • At a minimum, we are requiring the bottom of the drainage swale to be at least eight feet wide and at a slope of 1.8%. Based on the city's Storm Water Management Plan, we calculate the depth of flow in the swale to be approximately six inches deep. The spot elevation at the upstream end of the proposed driveway culvert should be lowered 952.0 and the driveway emergency overflow should be lowered to 952.5. By sizing the swale to the width and grade noted and lowering the swale elevation to 952.0, the two feet of freeboard requirement will be met. • The city should obtain a drainage easement over the drainage way or pipe(s) along the western side of the property once the final means of storm water conveyance and location are finalized. If you have any questions, please call me at(651)604-4894. Yours very truly, BONESTR00 %—�� � Darren Amundsen Cc: Tom Kellogg ��J � �� � 1��'� 7 /�Ic_�� S f�-��'� �(�� x S� .