Laserfiche WebLink
BOLTON 2638 Shadow Lane <br /> Al Suite 200 <br /> & M E N K Chaska, MN 55318-1172 <br /> Real People. Real Solutions. Ph: (952) 448-8838 <br /> Fax: (952) 448-8805 <br /> Bolton-Menk.com <br /> February 3,2021 <br /> City of Orono <br /> Attn: Jeremy Barnhart <br /> 2750 Kelley Parkway <br /> Orono,MN 55356 <br /> RE: Preliminary Plat Application <br /> Orono Crossing <br /> Engineering Review#1 <br /> Dear Jeremy: <br /> As requested,I have completed an engineering review of the revised documents submitted for the above <br /> referenced project. We offer the following observations, comments,and recommendations for your <br /> consideration: <br /> 1. Three filtration basins are proposed on-site to meet regulatory requirements for stormwater <br /> runoff management. The following must be considered regarding stormwater management: <br /> a. Per City requirements,the proposed stormwater management system must limit proposed <br /> peak runoff rates to that of existing for the 1, 10, and 100 year—24h hour events. Per <br /> NPDES MS4 requirements,the system must treat the water quality volume,calculated as <br /> 1"times the sum of new and fully reconstructed impervious surface. <br /> b. The Stonebay regional pond located to the west was constructed to provide rate control for <br /> stormwater runoff from this parcel. Due to rule changes since the pond's construction <br /> though,additional measures must be installed to meet current State(NPDES)and <br /> Minnehaha Creek Watershed District(MCWD)requirements limiting discharge of runoff <br /> volume and Total Suspended Solid(TSS). <br /> c. Even though the regional pond was constructed to provide rate control,the additional <br /> measures(filtration basins)are maintaining estimated peak runoff rates from proposed <br /> improvements to that of existing conditions for the site. <br /> d. Water quality calculations have been provided. Due to site soils not being conducive to <br /> infiltration, filtration has been provided, in addition to the detention in the regional pond,to <br /> treat the water quality volume. Proposed measures will remove more than the required <br /> 80%TSS load. <br /> e. The condition of the regional pond west of the site must be reviewed by the City and <br /> Contractor prior to any work. The pond bottom must be verified with survey prior to any <br /> work, and once work commences,the Contractor shall be responsible for removing any <br /> sediment added to the pond due to site construction. <br /> 2. Storm sewer has been adequately sized to accommodate runoff from the 10-year event. <br /> 3. Final Plans must include the following: <br /> a. Grading,Drainage, and Erosion Control Plan <br /> b. Street Construction Plan <br /> c. Utility Plan(profiles must be provided for sanitary sewer,water main,and storm sewer) <br /> N:\ORNO\Surface Water Management\MS4 Administration\MCM-5_Post-Construction Stormwater Management\2_Site Plan Reviews\Orono <br /> Crossing\OronoCrossing-PrePlatReview_2021-02-03.docx <br /> Bolton&Menk is an equal opportunity employer <br />