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A-2. Highover Boulder Wall UpdateMEMORANDUM CIff OF TO: Todd Gerhardt, City Manager CHANNSEN FROM: Paul Oehme, Director of Public Works /City Engineer A U 7700 Market Boulevard DATE: September 8, 2014 0 ' PO Box 147 Chanhassen, MN 55317 SUBJ: Update on Highover Boulder Wall - PW 116D Administration The spring of this year was recorded as one of the rainiest springs on record. The wet Phone: 952.227.1100 BACKGROUND Fax: 952.227.1110 the maximum wall height for a boulder wall is 20'. This wall is about 20' tall. The wall In 1997, the Highover Development was approved by the City Council. The Building Inspections development included a large boulder wall at the entrance of the development to preserve Phone: 952.227.1180 trees and for an aesthetic entry into the neighborhood. Through the development process, Fax: 952.227.1190 the City secured an outlot at the comer of Lake Lucy Road and Highover Drive for a Engineering future trail corridor. The trail however was never constructed and is not in the Trail Phone: 952.227.1160 Comprehensive Plan. The boulder wall is constructed on the City property and within the Fax: 952.227.1170 City right of way. Only a small portion of the boulder wall is on private property. The Phone: 952.227.1125 adjacent homeowner and the Homeowners Association (HOA) maintain the City -owned Finance property. Phone: 952.227.1140 HOA and negotiate a sale of this land. Fax: 952.227.1110 n1Q!'TTQQYnV Park Recreation The spring of this year was recorded as one of the rainiest springs on record. The wet Phone: : 952.227.1120 spring was capped off on June 190' with a 5" rain event in less than 6 hours. This event Fax: 952.227.1110 the maximum wall height for a boulder wall is 20'. This wall is about 20' tall. The wall caused soil around the wall to become over saturated which weakened the soil and caused Recreation Center the wall to fail. Some of the boulders fell on Highover Drive. City crews removed the 2310 Coulter Boulevard boulders from the street. A portion of the wall continued to move after June 19th so it Phone: 952.2271400 was decided to take down the portion of the wall that was still moving due to safety Fax: 952.227.1404 concerns. Planning & Natural Resources The City has hired a retaining wall engineer to redesign the portion of the wall that failed. Phone: 952.227.1130 The homeowner has requested the wall remain a boulder wall. The wall engineer stated Fax: 952 227.1110 the maximum wall height for a boulder wall is 20'. This wall is about 20' tall. The wall will be constructed outside the right of way along Highover Drive. The current estimate Public Works for reconstructing the boulder wall is $95,000. 7901 Park Place Phone: 952.227.1300 The wall failure reconstruction is eligible for FEMA funding. The amount of FEMA Fax: 952.227.1310 reimbursement is not known at this time. Staff is planning to meet with FEMA representatives to review this project on September 3rd. The portion of the wall on Senior Center private property is not eligible for FEMA funds. It is proposed the HOA and/or the Phone: 952.227.1125 homeowner pay for this portion of the wall. Since the City does not have a use for the Fax: 952.227.1110 outlot that was originally planned for a trail corridor, staff would like to approach the Web Site HOA and negotiate a sale of this land. www.ci.chanhassen.mn.us Reconstruction of the wall is planned for late September if all agreements can be worked out. Attachment: Site Plan g:\eng \public \pwl 16d 2014 storm event \bkgd ws 090814 highover wall disc.doc Chanhassen is a Community for Life - Providing for Today and Planning forTomorrow i KPI ix X �( '! f V/ Wall failure ",,1 x / - x X jx ix s lw- X I —} D33 �X e s x fps_✓ d� 10,3 l a X/x _1 -5037 X 9 x � �L —.� Wier xi x Bank fail -� S89°01'57 °W ( �X x � 1 159.85 x x x x 9z z { 0 00 { c Ln { �P 4d.pP OGV.ILTY CVMIIY MV, pydgpCpl� 0 OMVT'VNl oa(XIfffO OOY� Q1YMR:NHMJIMR.VNItIV QED SNm nnAT0115 0 10 ID YM p A N M Po Po 101 110 Idl IA IN IA Itl IA Itl 1Po llN 110 i9l 9N0RJq"'r BOULDER WALL 1- FRONT FACE ELEVATION CIVIL DESIGN P R O F E SS 10 N A L S Pf W LYNDAIFAVZN199OVOM .9Urt¢YOBI�OWN�VN�fHID PNON6bSE1301y1E P1Ml)J9119BJ�WPA9RPvl•.NPl6(ON D WA Br Pm CID 6811 HIGHOVER DRIVE CHANHASSEN, MINNESOTA am JUL 30, 2014 rwc PRELIMINARY SITE PLAN "°°4, 14A 1 405 X / i 1040-- x aw- –10A� x �M O N x