12-08-1997 Council Packet - Laserfiche WebLink

Home Browse Search

Bcnestroo. ,7oscne AnJcrtik t^nj AiSOOMei Inc n Affirm^itive AcTion Equ^I Opportunity Ernployer Prmcip^li Otto G tJcnestroo PE • Joseph C Anpemk. P£ • M^irvin L SorvHk^ PE • PichiUd E Turner. PE • Glenn R Cook PE • Robert G Schunfcht PE • Jerry A Bourdon PE • Robert W Rosene PE and Susan M Eberlin. C PA . Senior CorisuUants Associe*re Prmcip.^li Howard A Sanford PE • Kedh A Gordon PE • Robert R Pfefferie PE • Richard W Foster. PE • David O Loskota PE • Robert C Russek. A l A • Mark A Hanson. PE • Michael T Rauimann. PE • Ted K Field, P£ • Kenneth P Anderson PE • Mark R Rolfs. PE • Sidney P Williamson. PE L S • Robert F Kotsmith Offices St Paul Rochester Willmar and St Ooud VtN • Vi; .saukee. Wl ' ■■ Vwl.'*- Bonestroo Rosene Anderlik & Associates Engineers & Architects November 13,1997 Ms. Elizabeth Van Zomcrcn City Planner/Zoning Administrator City of Orono Post Office Box 66 Crystal Bay, Minnesota 55323 Re: Lake Minnetonka Woods File No. 139-2308 Dear Liz, We have reviewed the revised preliminary construction plans for the proposed Lake Minnetonka Woods planned residential development consisting of 30 townhomes. The site is located on Lots 2 and 3 and the west 6.29 feet of Lot 4, Block 9, Townsite of Langdon, along the north side of CSAH 15. We have the following comments in regards to engineering matters. 1 Utilities: The sanitary sewer and water main designs appear acceptable from an engineering standpoint. Details should be provided with the final plan set Our expectation is that Livingston Avenue will be extended westerly sometime in the future. We would recommend extending the sanitary and water main stubs to the west property line as part of this project. Service locations should be shown on the final plans with sanitary services located 3 feet downstream from water services. 2. Drainage: The drainage area map should include the boundary for flows to the northerly wetland and CB 55 to verify that the proposed 12-inch RCP under Livingston Avenue is adequate. The 20 minute time of concentration used for some of the calculations seems high for this site. We would recommend revising the storm sewer and ponding calculations for developed conditions using a maximum time of concentration of 15 minutes. Pipe grades and / or pipe sizes between CB52 and STMH 5 1 may need to be revised. A paved swale or some type of erosion control measure should be piovided at the downstream end of the 8-inch HDPE pipe. Details of the pond outlet control structure and bat tled weir should be provided for review. The timber weir may be a future maintenance problem. The City may want to consider an alternative outlet structure design without the weir where skimming is provided by a submerged inlet pipe to the structure. 3. Streets: The 19 units being served by the temporary cul-de-sac on Livingston Avenue exceeds the maximum of 10 units allowed by City standards. The horizontal alignment proposed for Livingston Avenue does not meet the City standard for 30 mph design. The radii should be increased to 275 feet or reduced speed warning signs installed. All proposed vertical curves do meet the 30 mph design standard. We would recommend that Livingston Avenue be constructed to the westerly lot line as part of this project. The proposed driveway to serve the 11 units on Blocks 3 and 4 docs not meet any of the City design standards for private streets relative to right-of-way width, minimum paved width or maximum number of units on a cul-de-sac. Emergency vehicle access to those units on Blocks 3 and 4 will be a problem and tlie City should review the plans with the appropriate emergency officials. Typical street sections should be provided for Livingston Avenue and the private drive. A geotechnical analysis and R-valuc recommendation should be submitted to verify the proposed pavement design. Please contact me at 604-4863 if you have any questions regarding this matter. Yours very truly, BONESTROO, ROSENE. ANDERLIK, & ASSOCIATES. INC. Tom Kellogg 2335 West Highway 36 • St. Paul, MN 55113 • 612-636-4600 ■ Fax: 612-636-1311