05-26-1992 Council Packet - Laserfiche WebLink

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5^ r- *’. .\‘ : -I M * -r w U- w }'p^ ’'i'',.v ‘■r V i'. Sf ... At'-. :» li'^' '• • •: f ‘ -r : m ■*■“■■ J- :ill.y. >;s idl Bonestroo Rosene Anderiik& Associates Engineers A Architects H Oqo Q BonrBioo Aooen w Aoiene PE* Joseph C Andpruli PE Mjrvm L Sofvjtt PE •<hj*d E Turner P€ G«enn B Coos. PE Thomas E Noyes PE Eopen G SchuTttCht P6 Susan M Ebersn C P ^ •Semor ConsuEanf HOM«d A santoid. PE Keen a Gotaon PE Aocet * P^*»y» P£ Bcnara W Ponef PE Oewd O LOSkM PE (tooeft C Buucft AIA Jerry A SouAtOn P£ Mart A Mamon PE Michaei T daotmann PE Teo fc Fe« P£ Thomas • Anoerson A i A Oooald C Butgjrdt PE ’’Nsmas E Angus PE Gary F ByiaocJpr p£ »smae* Wamne* PE Mcnae* P «£u pe ^^nes M Bmg A iC P Thomas ^ iNterson PE Micnan C Lynch PE >ames » Maonm PE jerry O Pprmcr »E Kerr«ch P Anderion PE Mart ff iDBl PE Mart A Sec PC ^ Morvrs PE Oamn J Fogerion PE Phmp j Cajv%en. pE Mart 0 VA/M. PC Mies B ienien PE L Phikp Gravel M. PE Kjien L Warner PE F Tbdd Power pe Keen c Taocs pe Sha^ O Guajfion PE CecAO OlKrer Pc ChJrtes A EncKsort Leo M Paweniry Nartan M OfO»^ James F Engemae* May 8, 1992 Ms. Jeanne A. Mabusth Building A Zoning Administrator City of Orono Box 66 Crystal Bay, MN 55323 Ibii Re: Camp Teko Property Conditional Use Permii AppL #1733 Our File No. 139-1733 Dear Jeanne: We have reviewed the application and supporting documents submitted for a conditional use permit on the Camp Teko property. There are several significant engineering issues related to the constructability of the improvements. Directly to the north of the existing steps and proposed start of the riprap is a ditch block. The ditch b’oek directs the runoff into a PVC culvert which outlets in the ditch approximately 200 feet to the south, the culvert exists with little or no cover and will create a problem when constructing the proposed ditch. Also, the pathway leading fr^ the mam trail to the existing steps crosses the ditch at grade and is in poor condition. The existing culvert should be removed and a portion should be salvaged to be reinstalled at the proposed ditch grade. The culvert could be used at the ditch block and at the pathway. This way, the pathway could be built up above the ditch bottom and improved with gravel. The proposed Class II riprap may not be suitable for the high velocities expected along tne ditch bottom. Also, the 6" average size is too easily displaced by the numerous pcdesmaiis in the aiea. We recommend Qass III riprap which has a 9" average size. The filter fabric «hniiki he fl non>woven fabric in accordance with Mn/DOT specification 37.33, type IV. The area identified as the last 120 feet of drainage ditch is of the greatest concern. The main trail and ditch are confined in a very small corridor between a large oak tree, a picnic canopy and the steep bank to the west If this trafl is to be used for any purpose other than pedestrian traffic, it should be widened, realigned, and improved. It appears as though it if presently used for vehicle access to the lake. The steep bank to the west h^ an approxiniate slope of 1:1 (horizontal to vertical). The minimum acceptable slope, with fabnc and riprap, is 3:1. To construct this slope, the trafl must be removed, or the bank must be excavated significantly, resulting in the loss of several of the large oak trees in the area. 233S West Highway 36 • St. Paul, MInnesoU 55113 • 612-636-4< ■ V ‘ V ___________________________________________________________________________________________________V. -V’____________________________________________________________________________________________________________________________________________________