Laserfiche WebLink
'! <br />! <br />! <br /> ! <br />I <br /> I <br /> I <br /> I <br /> I <br /> I <br /> I <br /> I <br /> ! <br /> I <br /> I <br /> I <br /> I <br /> I <br /> I <br /> <br />45. Design calls for 18" RCP from CBMH-68 to CBMH-71. Please revise. <br /> <br />46. <br /> <br />Minimum size of storm sewer is 15" RCP. 12" RCP is allowed only for a lead <br />to a catchbasin across the street. <br /> <br />LIFT. STATION DETAIL [SHEET 16) <br /> <br />47. <br /> <br />Provide 10' horizontal separation between watermain and forcemain (STA <br />30+00 to 30+60), <br /> <br />48. Include a detail for an ai~' release valve manhole, <br /> <br />49. Call out invert elevation of 4" DIP discharge where it exits the wet well. <br /> <br />50, <br /> <br />1" PVC sump discharge line could pose maintenance and/or clogging <br />problems. Recommend 2" inch minimum. <br /> <br />STORM SEWER DESIGN <br /> <br />The following comments on the storm sewer design correspond only to the storm sewer <br />to be constructed in the first addition as platted. Design calculations for any subsequent <br />additions have not been reviewed, as they shall be submitted and reviewed at a later <br />date. <br /> <br />51, <br /> <br />A typical lot where the front yard and the front half of the house drains to the <br />street will have approximately 52% impervious area (including half of the <br />street), Use a rational method runoff coefficient, C, of 0.50 for all drainage <br />areas where the front half of the house and the front yard drain to the street. <br />Lower runoff coefficients may be used for backyard areas and lots in which <br />the rear yard also drains to the street, but shall be justified. <br /> <br />52. <br /> <br />In several areas the storm sewer connects to,backyard catchbasins. These <br />pipes need to consider the hydraulic grade line for the 100 year storm event <br />to set the flood elevation to ensure homes are protected, <br /> <br />53. <br /> <br />Provide time of concentration calculations, Consider the exception (for large <br />inflows) when there is more than one source to a given point in the drainage <br />system, as stated in the Mn/DOT Drainage Manual, <br /> <br />54. <br /> <br />Revise the Drainage Area and Storm Sewer System Plan to match the most <br />current Construction Plans and Grading Plan." The revised areas storm sewer <br />data shall be reflected in the Storm Sewer Design sheet. <br /> <br />IlHakanson <br />Anderson <br /> Assoc., Inc. <br /> Page 4 of 7 -99- <br /> <br /> <br />