Laserfiche WebLink
2.Explain in detail the pre and post impervious surface is sq. ft. in the submitted stormwater <br />report. Also, separate the projects as phase 1 and phase 2 or explain the how the <br />stormwater infrastructure works together. <br />The preliminary plans have been updated with pre and post hardcover calculations forboth projects and the <br />stormwater report has been revised to match. The proposed stormwater basin will work together for both projects. <br />The existing/proposed hardcover calculations show a reduction. Staff cannot verify these <br />numbers. Please the hardcover numbers. <br /> <br />3.Within the stormwater report, include pre and post for volume and water qualitytreatment. <br />The stormwater report has been revised to include this information. <br />The report does not match calculated hardcover existing/proposed numbers. The discrepancies <br />need further explanation. <br /> <br />4.MnDNR will follow up with comments regarding requirements for state floodplain and <br />the Mississippi River Wild and Scenic and Recreational requirements. <br />So noted. <br />DNR comments were received on January 11, 2019. See attached. Include a response to all of <br />their comments. <br /> <br />5.The project must meet all state and city ordinance requirements for the floodplain regulation. <br />No site improvements, including stormwater basin expansion and construction, are proposed within the <br />100-year base flood elevation boundary. <br />Any improvement within the floodplain will need approval prior to installation. <br /> <br />6.Submit soil borings and infiltrometer tests for all proposed infiltration basin areas. <br />A geotechnical report was completed in 2017 for this site but does not include the area below the bluff (where the <br />infiltration basin is proposed) or the area between the existing parking lot and the Elk River Lodge site. This <br />report will be amended to include soil borings in these areas and submitted separately. <br />Staff will review these documents once they have been submitted. <br /> <br />7.Submit soil borings for the proposed infiltration basin (within proposed area) in order to <br />identify water baring soils. The infiltration basin details must meet state requirements and <br />have a separation of 3’ from the proposed bottom of the basin and water baring soils. <br />Please refer to the response to the previous plan review comment. The infiltration basin will be designed, <br />expanded and constructed to meet State and City requirements for groundwater separation. <br />Staff will review these documents once they have been submitted. <br /> <br />8.Stormwater pre-treatment is required prior to any proposed infiltration basins. <br />Stormwater pre-treatment will be provided using manhole sumps and sized using the MIDS calculator <br />during the construction documents phase. <br />Staff will review these documents once they have been submitted. <br />9.The plans show a basin bottom of 861.00 but the stormwater report lists 860.00. This needs <br />to be addressed. <br />The proposed infiltration basin will have a sloped bottom from elevation 863 down to elevation 862 but <br />with no area that the 862 elevation. A basin profile detail will be included in the construction documents. <br />Staff will review these documents once they have been submitted. <br /> <br />