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<br />Drainage Area No. 5A and Pond AnI> (':aster Plan Drawing No.7): <br />Thi:; area ,,,as designat:ed a-s'-;ZI,m,,:)]'a --f'Tl1',:: irt thE;-j'>hase-A-J{elX)-it. <br />In Lhis area, the conE:truc.tion of Pend !'.-B and a concrc:te- <br />lined flood channel by the city of l'.urora has allevi,).tElc', most <br />of 1::he flooding problems. JI1odificati:>n:; to Pond A-B ane re- <br />quired according t.O the Phase A re~)r:rt and the reevaluation <br />dur:_ng thi.s Phase B st:udy. ThE' IilodifLc'3-tions will incI'lcase <br />the storage volume to cont:ain Ute lCVI'-year flood and lengthen <br />the emergency spillway to pass the S~. safely. In addition, <br />the existing outlet works, Iolhi.c':l currenl:1y release s,:onn water <br />from Pond A-B into the Highline Canal, will be abandoned <br />because the Iiighline Canal is an irri']ation facility and does <br />not have capacity for stormwater. I'u:ctllermore I '~:hE' existinq <br />orij~ice-type outlet structure i~; modific?d as part of th_Ls <br />preiiminary design to be a drop inlet. sl:ructurEl. T'1,' vC'oposed <br />outlet involves disconnecting the exist~ng 36-inch RCP (which <br />is connected on t:he urstream end .to t.'1e existing ori~.i.ce-t.ype <br />outlet structure) from the existing' storCl Se\'1er alone; the <br />south side of Alameda Avenue and reconnecting to the ,lroposed <br />96-inch storm sewer along Alameda l\venue_ <br /> <br />In order to increase the s1:OJC'agc: vc]ume,. consideratio'1 of <br />dee~tening Pond A-B versus raising t~e embankment was nade <br />in t.his preliminary design. The embankment is proposed to <br />be raised to an elevation of 5471 (an in2rease of two ft) <br />bece.use deepening the pond would increac:e the volume by such <br />a small amount that the embanknK:nt would have t.O be rai,;ed <br />anY"'ay. In addi t.ion, deepening the [lond would require that <br />the sprinkler system be modified and C10 entire bottom be <br />regr aded and sodded. The E~I11erSlency ~:;pi ll-v.7ay was des igned <br />to an elevation of 5468.7 ft (an increase of 1.7 ft). 1m <br />additional 540 feet of emergency spil~w~{ at an elevation <br />of 5468.7 fi: was proposed along the east: sid,e of tIl.e de1:ention <br />pond. The side slope of the embankm3!lt" at the inner face <br />"las changed from t'l.e existin9 8: 1 (1;:)):1 2:ontal: vertical) to <br />4:1 to increase the storage volume a'ld Lo provide material <br />for embankment fill. The improveelen U: t.O Pond A.-.I) an" E;hown <br />on Master Plan Drawinq No.7. <br /> <br />The modifications to :Dona ~~-.n :la~n~ t<) be C\nprovect hy tliP ')i vi:: inll <br />of Kater Resources, Office of the St3.te Engi:l.eer of Colorac.o <br />prior to the construction accordinq to Gl.apter 148-5-5 of <br />Colorado Revised S.tatutes, 1963, AC'2orclng .to .the StatE' <br />Engineer's Regulations, "in no insta:l.ce shall the vertical <br />distance be1:ween the highest: point il. thE" floor of the spillway <br />and the lowest point in the crest of the dam be less than 5 feet <br />except with the written approval of the State Enqineer". A <br />written approval should be obtained from the Stat.e Enqineer <br />prior to the final design of Pond A-'3 because of the limitations <br />of the present site. <br /> <br />-..23.. <br />