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Ms. Katie Larsen <br />01/04/2024 <br />Page 2 <br />Jansen Addition Engineering Review <br />3. Shift the northern limit and overflow weir of the infiltration basin to the south <br />10' to allow for overflow drainage to be established on this property prior to <br />discharging to the north <br /> <br />• Stormwater Management <br /> <br />Stormwater management for the site consists of a proposed infiltration basin. However, <br />based on site layout, stormwater management is not required under City ordinance. <br />Comments on the proposed stormwater design are offered below. <br /> <br />Pre- and Post- Development Discharge Rates (cfs) <br />Condition 2-Year 10-Year 100-Year 10-Day Snowmelt <br />Existing 0.61 2.01 6.17 Not required <br />Proposed 0.51 1.00 4.46 Not required <br /> <br />Comments: <br />1. To be conservative in HWL modeling, exfiltration cannot be modeled as an <br />outflow. Please remove exfiltration on node P1 of the proposed conditions <br />HydroCAD model and update the 100-yr HWL accordingly. <br />2. Permanent turf reinforcement matting such as Armormax is not allowed as a <br />form of stabilization for BMP overflows. Riprap can be extended to cover the <br />overflow weir. <br />3. While noted in the infiltration basin detail, please show silt fence around the <br />basin on the erosion control plan sheets to ensure proper sediment control is <br />provided. <br /> <br />• Water Supply <br /> <br />The proposed water will be supplied by three existing 1-inch Type K copper services <br />extended to the lots. <br /> <br />Comments: <br />1. An additional water and sanitary sewer service stubbed from Arlo Lane will <br />need to be removed back to the main. Restoration to include; <br />• Roadway section shall be 3.5” bit over 8” class 5 <br />• Curb and gutter - see City standard details. <br />2. Show connecting the existing house (Lot 2) to the provided sanitary sewer <br />and water service stubs with construction <br />• Water service stub is 1" copper (Type K) <br />3. Abandon/seal the existing well for Lot 1 per MDH requirements with <br />construction <br />• Note the existing well may be left in place for non-potable irrigation use <br />if MDH setbacks can be met from the proposed utility services <br />(currently they do not appear to meet setback requirements). <br /> <br /> <br />17