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• BO I_TON & M F== N K , I N C. Consulting Engineers & Surveyors � 2638 Shadow Lane, Suite 200 •Chaska, MN 55318-1172 Phone (952)448-8838 • Fax(952)448-8805 www.bolton-menk.com September 25,2014 City of Orono Attn: Christine Mattson 2750 Kelley Parkway Orono,MN 55356 RE: Building Permit Application 2014-00747 1560 Tanglewood Road Engineering Review#1 Dear Christine, As requested, we have completed an engineering review of the documents submitted for the above referenced project. Our current review is based on the following submittal items: • Construction Plans prepared by Civil Methods,dated 8/14/14 • Culvert Design Narrative and Calculations prepared by Civil Methods,dated 8/1/14 We offer the following observations,comments, and recommendations for your consideration: 1. Siltfence should be routed on the north side of the alternate drainfield site to ensure it is not impacted during construction. 2. Protection fencing should be installed around the primary drainfield to ensure it is not impacted during construction. 3. Perimeter erosion control BMPs and protection fencing should be installed by the Contractor and inspected by the City prior to any land disturbing activities. The Contractor must provide a minimum 24 hour notice prior to inspection. 4. Hydraulic calculations should be revised to match elevations indicated on Construction Plans. 5. Hydraulic calculations for the 100 year rainfall event must be submitted to determine potential impacts to adjacent property and structures. 6. Since HDPE is susceptible to floating,the applicant should consider using a corrugated metal or reinforced concrete culvert in lieu of an HDPE culvert. 7. The upstream culvert invert is indicated at 959.2,but a 960 contour is not shown upstream of the culvert on the plan. The plans should be revised to indicate the correct location of the 960 contour. 8. Grading on the east side of the proposed tennis court may impact the west ditch bank. Once the plans are revised to indicate the correct location of the 960 contour,this area should be reviewed further to ensure no impacts are proposed. Additional retaining wall may be necessary in this area to construct the court at proposed elevations. 9. A financial security of$2,500 from the Applicant is recommended for erosion control and engineering oversight. The financial security is intended to provide protection in the event that it becomes necessary for the City to install or maintain erosion and sediment control within the project DESIGNING FOR A BETTER TOMORROW Bolton&Menk is an equal opportunity employer