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ITEM 4.1_attachmentMain Office: 1 1akanson 3601 Thurston Avenue, Anoka, MN 55303 Anderson Phone: 763/427-5860 Fax: 763/427-0520 www.haa-ine.com Memorandum TO: Planning Commission/City Council BY: Ronald J. Wagner, P.E., City Engineer CC: Lori Johnson, City Administrator Dan Licht, City Planner Tami Loff, City Clerk Kurt Neidermeier, Utilities Manager Dan Schmidt, Sathre Berquist Dan Berning, Ziegler Custom Homes Jeffrey and Kelly Busch, 12830 43rd St NE St. Michael MN 55376 DATE: February 10, 2016 RE: Riverpointe 6th Addition — Review We have reviewed the Preliminary Plat and Final Plat for Riverpointe 6th Addition for conformance to City standards and have the following comments: Preliminary Plat 1) Driveway grade exceeds maximum driveway grade allowed. Maximum grade allowed is 10%. Driveway as shown on preliminary plat is approximately 12%. 2) The site plan must be revised to provide for a nearly flat turnaround at house so that someone does not have to back down a steep, curving driveway in the winter. 3) Retaining walls on either side of driveway and around the house exceeds 4' in height. A protective fence is required by the Building Code along the high side of any retaining wall exceeding 4'. Retaining walls in excess of 4' are required to be designed by a professional engineer licensed in Minnesota. Protective barriers along the driveway retaining walls, on down slope side, are suggested due to grade and width of travel surface. 4) Two culverts are shown providing drainage under the driveway. Storm water calculations determining sizing for culverts must be submitted for review and approval by the City Engineer. Size, type and inverts of existing utilities within 150' of the project boundary must be shown on the preliminary plat. 5) A driveway profile showing watermain service line and sanitary sewer service line is required in the final plans. Sewer service line shows no clean outs along approximately 500' of length. The utility plan must be revised to provide cleanouts at all bends and at least midway the length of the service. The utility plan must also indicate type, size and grade of service line. 6) The utility plan must show watermain type and sizeand analysis must be completed to ensure existing City pressure is adequate per size of watermain. (i.e. that the pressure at the house is still adequate after checking headlosses associated with 500' of smaller conduit and a rise of approximately 30 ft. 2/11/2016 Page 2 7) Cross sections of the driveway and retaining walls is required and are subject to approval of the City Enigneer. 8) Typical section of driveway is required and is subject to approval of the City Engineer. 9) Temporary and permanent erosion control is required to be shown. A NPDES permit would be required if over 1 acre is disturbed. 10) Outlot A has no functional purpose and the preliminary plat is to be revised to combine Outlot A with Lot 1 to create a single parcel. Final Plat 1) Ingress/egress and utility easement over Outlot A would be required if ever sold to another party. 2) Drainage easement is required along waterway channels. There are two waterway channels within the subject site; one running NW to SW under driveway across both Outlot A and Lot 1 and one along the north easterly portion of Lot 1. 3) A 20' conservation easement along the wetland is required. Conservation easement signs (wetland buffer) are required at intervals which indicate the approximate line and can be seen from one to the next. 4) The drainage and utility easement along the west property line must be 10' rather than 5' when adjacent to unplatted property. 5) Outlot A is to be combined with Lot 1, Block 1 to create a single parcel. Recommendation Many items need to be shown and analyzed. The exceedance of driveway slope has merit due to the uniqueness of the site. As long as the owners are aware of the issues regarding the steep slope and potential safety and accessibility issues in adverse weather conditions I would advise allowing it. At this point we cannot recommend approval due to the number of items that need addressing prior to Planning Commission consideration of the applicaiton. Hakanson 1,16IIAnderson