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'Ttro G Borestloo, PE <br />Bonest= <br />RobePC <br />� <br />Joseph w *. PE <br />J" <br />A Lemberg, PE <br />Rosene <br />RKrardd Turner. PE <br />RKmard E <br />Anderlik & <br />is <br />n� R Cook. PEE <br />Assoelates <br />Thomas E moves, PE <br />Robert G Sc"unKht. ►E <br />Marvn L Soevala. ►E <br />Engineers a Architects <br />May 19, 1988 <br />Honorable Mayor and City <br />Council <br />City of Orono <br />Box 66 <br />Crystal Bay, MN 55323 <br />Keith A Gordon. PE <br />Thomas W Polrwwn. PE <br />RKhand W Foster. ►E <br />MKhael C lynch. PE <br />Doarld C Sur"rdt. PE <br />James R Maland. PE <br />Jerry A Bourdon. PE <br />Kenneth ► Anderson. PE <br />Mart A Hanson. PE <br />Ktmh A Bachman. PE <br />Ted K Field. PE <br />Mart R RDIh. ►E <br />MKhael T Rautmann, /E <br />Robert C Russek. A I A <br />Robert ItPfeNerle. ►E <br />Thomas E Angus. PE <br />Wind O Loskota. ►E <br />Howard A SaMod. ►E <br />Re: Highvood Storm Sewer Improvement - Report Supplement <br />Project No. 87-4 <br />File No. 13933 <br />Dear Mayor and Council: <br />Charles A EnKk$On <br />Leo M Pawelsky <br />Harlan M Olson <br />Susan M Ebemn <br />Mart A Serp <br />This report supplement to the Highwood Storm Sewer Project reviews two addi- <br />tional options for controlling the storm water runoff from the drainage area. <br />The feasibility report provided for construction of a 21 inch outfall line. <br />This report supplement reviews Option II which provides a twelve inch outfall <br />line and Option III which provides a ten inch outfall line. <br />Option I as provided in the feasibility study would allow a discharge of <br />between 0.5 and 1.2 cfs until the water in the Sauers backyard reaches <br />elevation 947.5. The water would then be discharged at a rate equivalent to a <br />5 year storm return frequency (17.5 cfs). Under Option I, the water could <br />reach an elevation of 948.0 for a 100 year storm event. <br />Option II would provide a 12 inch outfall line with a discharge capacity of <br />(2.5 cfs). The water would back up to an elevation of 948 for a 5 year storm <br />event. The water would backup to an elevation of 949 for a 100 yea- storm <br />event. <br />Option III would provide a 10 inch outfall line with a discharge capacity of <br />1.5 cfs. The water would backup to an elevation of 948.5 for a 5 year storm <br />event. The water would backup to an elevation of 950 for a 100 year storm <br />event. <br />The smaller pipe size for either option II or III would reduce the project <br />cost slightly. The following is a summary of the project costs for each <br />option: <br />Pine Size <br />Pro . Cost <br />Assmt. Rate <br />Option I <br />21" <br />$19,500 <br />$0.066 <br />Option II <br />12" <br />$17,600 <br />$0.059 <br />Option III <br />10" <br />$16,800 <br />$0.056 <br />Page 1. <br />24 <br />2335 West Highway 36 • St. Paul, Minnesota SS113 • 612-636-4600 <br />