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Drainage System from .the Intersection of Alameda Avenue and Havana Street'tOl:he(Jppe~:-: r,owIi::~~~i~~c~fron Pond-: (M'~!>te_~" pIan Drawing Nos. 9, 10, 11, 121:; The drainaqe system is desiqned to convey stormwal:er from -'t.he i n"ce n38cti.on of I\lameda Av'~nue and Havana Street to t:he proposed 'Up:oer Lowry Deten1:ion Pond. Since the system will cross the LO'i'lrJ::-Y qo1 f course 1 a lOTN flow pipe with capacity for a 2-yea:r stOClTl "vent (263 cfs) was designed to convey 10'" stormwate:, f._Cows into the del:ention pond without overland flow and, cOflsequenU..y, without cHs- turbing the golf course. A swale-type channel has been designed by the Omaha District Corps 0= E:ngin'3e",:; to carry the di.fference between the 2-year and 10'-year stOC'l from the upstream watershed to the Upper Lowry Detention Pond. The channel was desiqned in sucl1 a way that the general layout of l:he golf course wi.ll not be disturbed. It is feasible to n="juce the lenqth of tJl(~ 72-inch Rep low flow pipe and connect to tJ:.'l ex:i.stinq 4n" st"orm drain. This should be investigated in the I'inal design. Flo:)d Channel Along Alameda Avenue I':rom Dayt:on S.tree1: to the -.-.-- . --.-.-( _._---------_.._.~-~-----------.._-- Upper Lowry Detent:ion Pond Master Plan Draw1nq Nos.. 12, 13, , .__._--_._-.-._--"._.~~----------==- 14, 15, 16): Th1S flood channel lS des1gned alonq the nortll sid.::' of Ala~meda Avenue to intercept the storm water from Windsor Gardens, the ups.tream drainage systl;,m, imd t:he overland flow up to 'i 10-yea.r storm. It is desi::rned for a IO-year storm event for the following reasons: (1) all drainage systems south of Alameda Avenue are designed for a :,...year storm event: " and (:2) the proposed Upper Lmvry Detention Pond will int:ercept all over-- land flow up to .the 100-YE,a.r storm from upst:ream of l:he proposed pond site. The flood channel wiLL be Cirass lined witch riprap a1: locations where there will be c:'1amwl chops or storm sewer con:~ections. The channel cross"-secJ:;:Lon used was a 3 percent slo::>ed bottom with a rectangular COlLcrE,te trickle channel to pre ITen.t channel deposition durinq :_uw flow period. Upper Lmvry Detention Pond (Master Flan Dra"ing Nos. 10, 12, 13') '['he proposEld Upp-er l~o;;ry--')etE;llt-io]';- Pond liii-E; be~cn -;'[esiqn- ed by t:he Omaha District Corps of E;n9in(:~ers and is shO'l.rln on the f1aster Plan Drawir..qs. 'r.1e pClnf~~ '>7i13 desisrned to contain the 100-year storm wit.flout: emerqency 3p:lllway overflow,. a.nd t:1e spillway was designed .to pa:;s tlie P,,'obable Maxirr.u.m :"lood (PI1!") without embankmE:nt failure.J.h", outlet from the '"ond is a 36-inch pipe which connects to t~e existinq 48-inc~ storm drain. The proposed Upper Lowry Detention Po~d has a storage volume of :nO--acre-feet at the em,,,rgency ;c;ri I.h:ay levEll. 'The emergency spillway will be 30e ft lcw). KeL.y Pond (HasteI' Plan DravrLng 1:0. 1. '1): 'j'he modific:ai:ion to the existing Kelly Pond Re-se:rvoIr-J=lij;:::b'(~'en desiqnec1 by 7.he Omaha District Corps of Enqineen: and i" shown on !laster Plan DraVlinC) No. 20. Since the site of teLe ;)roposed Upper Lowry Detention Pond was relocat:ed to a further dm.rnst:cearr. loca.- t.ion from that indica.t.cc1 in .the. Pf12":(' A report, t:'~e L3torag(, volume required at the exis"tin9 KelJ.y HDac1 PesE~rvoi:r was reduced.. -2:1-