Agenda - Planning Commission - 02/01/2018

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Review File: Rum River Meadows Preliminary Plat Plan Review Engineering Review January 25, 2017 Page 3 of 3 outlets in the proposed model. The drainage areas must include offsite areas that drain to the site. There are existing catch basins in Tiger Street south of Armstrong Boulevard. These must be added to the existing conditions sheet along with the associated pipes and any culverts under Armstrong Boulevard or Tiger Street north of Armstrong Boulevard. Remove all proposed grading information from the existing conditions map. The proposed lot lines can remain to provide continuity between the existing and proposed maps. Proposed conditions Revise model to reflect the drainage areas noted on the existing model. Add labels to drainage areas on map corresponding to Hydrocad model subcatchments and ponds. Add the area east of Tiger Street to the model. The drainage areas must include all land that drains to the site. Identify the outlet for the 21" storm pipe. Expand the summary - Add calculations for sizing of infiltration basins. If infiltration basin also serves as stormwater ponding for the 100 year storm or back to back 100 year storm, the pond must infiltrate the largest storm in 48 hours. Provide Geotechnical data to support assumed infiltration rate. Add a table showing the existing and proposed runoff rates for the 2, 10 and 100 year storms for existing and proposed conditions arranged by pond number. Submit the Lower Rum River Watershed Management Organization (LRRWMO) application to the City for review. The City will then forward the application to the LRRWMO after review.