06-27-2005 Council Packet - Laserfiche WebLink

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^ i Bonestroo Rosene Anderiik& Associates Engineers & Architects 2335 West Highway 36 • St. Paul. MN 55II3 Office: 651-636-4600 • Fax: 651-636-1311 www.bonestroo.com May S, 2005 Ms. Janice Gundlach Planner CityofOrono Post Office Box 66 Crystal Bay, MN 55323 Re: 1146 Wildhurst Trail File No. 139-05-000 Plat No. 05-3100 Dear Janice: We have reviewed the revised site plans dated 5-3-05 for the proposed improvements to 1146 Wildhurst Trail. The site improvements include the removal of an existing house and boat house, the construction of a new house and detached garage along with the associated site grading. We have the following conunents with regards to engineering matters: • The revised grading plan shows a proposed retaining wall along the northwest lot line. The wall does not meet the city standard 5-foot set back from the lot line and should be revised. • The retaining wall system approaches 14-feet in height on the lake side of the home. This will have a massive visual impact from the lake and could have significant impacts on the property to the east in the event the wall failed. The wall height could be minimized if the house footprint was moved northwesterly towards the road 10 to 15-fect. • Retaining walls that exceed 4-feet in height require a separate engineered design and detail submittal. • The concept of routing storm water along the northeasterly side of the home and then turning it towards the center of the lot on the lake side of the home is good, although the proposed swale grades exceed the 5% maximum we typically recommend for a vegetated swale. The plans should include swale stabilization details or the swale grades should be reduced. • An existing catch basin is shown south and west of the home but no information is included as to the downstream pipe. City records indicate the downstream pipe discharged towards the center of the lot and flows were routed from the discharge point towards the lake through a swale. The swale conveyed the storm water around the southwest side of the boat house. This swale has silted in over the years and the drainage system no longer functions as it should. The grading plan should include the existing pipe information and should include infonnation as to how the swale can be regraded once the boat house is removed. • City records also indicate that at one time there was a downspout system in place along the northeast side of the home to route water away from the existing home. The city has verified that this system no longer functions and the property to the cast of this site has experienced water problems due to runoff from this site. The plans should include provisions as to how St. Paul. St. Cloud. Rochester. MN • Milwaukee. Wl • Chicago. It AfTfrnwlIv* A€timn/tquat Ofprnnmmp Iwplfg y amf Iwipioya Ownm^ It J