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Ms. Katie Larsen <br />4/3/2024 <br />Page 2 <br />Jansen Addition Engineering Review <br />(Plowe 2/29/2024) Note added. <br />•Adjust grading along the eastern side lot line of Lot 1 to allow for <br />drainage to reach the street. <br />(Plowe 2/29/2024) Grades adjusted and note added. <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 />(Plowe 2/29/2024) Basin Outlet shifted southward <br />•Stormwater Management <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 />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 1.21 5.65 Not required <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 />(Plowe 2/29/2024) Exfiltration removed. <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 />(Plowe 2/29/2024) Riprap used. <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 />(Plowe 2/29/2024) Silt fence added. <br />•Water Supply <br />The proposed water will be supplied by three existing 1-inch Type K copper services <br />extended to the lots. <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.