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• 2638 Shadow Lane <br /> BO LTO N Suite 200 <br /> & Ni E N K Chaska,MN 55318-1172 <br /> Real People.Real Solutions. Ph: (9521 448-8838 <br /> Fax: (952)448-8805 <br /> Bolton-Menk.com <br /> November 21, 2017 <br /> City of Orono <br /> Attn: Adam Edwards <br /> 2750 Kelley Parkway <br /> Orono, MN 55356 <br /> RE: Orono High School Fieldhouse Addition <br /> Engineering Review#1 <br /> Dear Adam: <br /> As requested,we have completed an engineering review of the documents submitted for the above <br /> referenced project. We offer the following observations, comments, and recommendations for your <br /> consideration: <br /> 1. Stormwater management proposed for the site to meet City,MCWD,and State requirements will use <br /> a wet retention pond and irrigation system using water out of the pond. The following should be <br /> considered regarding the proposed system: <br /> a. The intake for the irrigation wet well is proposed at only 1.5' above the pond bottom. A <br /> minimum 4.0' dead storage below the irrigation supply intake should be provided to allow <br /> sufficient storage for sediment deposition. The proposed system appears to have adequate <br /> impervious surface draining to the pond and pond storage to accommodate this revision and still <br /> provide over 90%reliability for the irrigation area proposed. <br /> b. The irrigation wet well should be relocated from the middle of the pond slope to the top in a flat <br /> area to allow easier access. <br /> c. The Metropolitan Council recommends treatment for reclaimed stormwater to meet regulatory <br /> limits based on the California Water Recycling Criteria,Title 22 Code of Regulations(same as <br /> the Minnesota State statute requires for reclaimed wastewater). For open access landscape areas <br /> (parks,playgrounds, schoolyards,ball fields,etc.),the irrigation supply should meet a total <br /> coliform limit of 2.2/100 ml. This level of treatment would require oxidation, filtration, and <br /> disinfection. The treatment system design should be submitted for review to verify adequate <br /> level of treatment will be provided. <br /> d. Irrigation rates should be monitored in perpetuity to verify reuse volume necessary to meet <br /> regulatory requirements is being provided by system. Reports should be provided annually to the <br /> City to confirm correct usage rates and allow City staff to complete MS4 reporting. <br /> e. If a complete review of the irrigation system is desired, irrigation plans and design calculations <br /> should be submitted for review. <br /> 2. The applicant will be required to obtain Minnehaha Creek Watershed District(MCWD)approval and <br /> permitting for their Erosion Control and Stormwater Management Rules. A copy of any approvals or <br /> permits required should be submitted prior to Final Plat approval. <br /> 3. The applicant has obtained a General Construction Permit(NPDES)to discharge stormwater <br /> associated with construction activity since more than 1 acre will be disturbed. A copy of the permit <br /> has been submitted to the City. <br /> H:\ORNO\C13113299\Orono High School\OronoHS-Review-1-2017-11-21.docx <br /> Bolton&Menk is an equal opportunity employer. <br />