02/14/2007 P&Z Packet - Laserfiche WebLink

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Comforts of Home Development Page 2 January 8, 2007 Drainage Review • City of Lino Lakes, Minnesota • 7. The proposed trail must be located beyond the 100 -year flood elevation of the proposed ponds and existing wetland. 8. The rain garden and lift station should not be in the same location, as currently shown on the Utility Plan. 9. Include depression storage located in EX -C in the existing conditions model and route EX -C and EX -E through the existing 24" culvert located west of the site. The proposed discharge rates for the 2 -, 10 -, and 100- year rates shall not exceed the existing 2 -, 10 -, and 100- year rates for the site. 10. The soil boring information on the SWPPP Plan indicates that the predominant soils on the site are Type A soils. Please clarify the curve numbers based on Type B soils used in the existing conditions model. Disturbed areas under proposed conditions are required to be Type B soils. 11. The lag/CN method is used to determine the time of concentration based on the hydraulic length and average land slope over the entire watershed. Therefore, the lag/CN method should not be used in combination with the TR -55 method for the determination of subcatchment curve numbers. 12. The emergency overflow for Pond 1 discharges to the CSAH 49 ditch; therefore, permit approval from the County may be required. 13. Approval from Rice Creek Watershed District is required. Minor Plan and Drainage Calculation Issues: 1. Show and label contours for all rain gardens and ponds on the Grading Plan and ensure that the contours on the Grading Plan are consistent with stage- storage values in the model. 2. Indicate the overflow elevation and location of the existing wetland, stormwater ponds, rain gardens, and road /parking lot low points on the Grading Plan. 3. Update the elevation of the 10:1 bench on the Grading Plan to correspond to the revised normal water level. 4. A pre - treatment device, such as a sedimentation forebay or vegetated filter strip, is required upstream of the infiltration areas to prevent accelerated decay of the infiltration capacity due to clogging. 5. The typical pond skimmer detail located on Sheet G1 does not illustrate the pond outlet devices as modeled. Update the pond skimmer detail to include details, such as orifice and pipe configurations, consistent with the outlet devices defined in the model. 6. Include catchbasin and culvert inlet protection details on the plan. 7. Include notes on the Grading Plan incorporating the following: 1) the infiltration areas are not to be excavated to final grade until the contributing drainage areas have been constructed and fully stabilized, and 2) final excavation of the infiltration areas should be completed using light tracked equipment to avoid compacting the basin floor.