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<br />sy.>lcm isnOlC~leffeclive. Dis<;ussionsbclweenvariousdepanmcnrsoftht:Cily revcalc<J
<br />thaI re<;m15lnlctionofparksalongOligarchy Ditch formuJti-usc f100dcomrol and recreational
<br />purposcs was nol viewed OUI " favotablc allernalivc at this lime. Alw. lhe required
<br />inve,[mCnl 10 bring lhe dilChup to ful12-yearcapacity was not viewcdas viable given high
<br />costs and the t..Cllh.l the ditch is nol p~sently a perm."",,! stormw.t.r managemem facility
<br />owned by the City, U is re<ommended Ihat ,he City continue 10 pursucdi!ICussio", (0 secure
<br />Ihe permanent use or lhe ditch for stormW.lcr conveya"".. and improvemen, plan' b<:
<br />dcvclol"'d inlhc fUlUre when ,uch wle oflhe ditch bccome, eosteffcclive.
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<br />Detention capacity of lhe pond at 21st A"cnoe and Hover Street ,hould !Ie secured.
<br />Available informal;on indicates that this pond is nOl City owned and maintained and therefore
<br />cannot he currently relied upon for ,tormwater managemem. Securing of this facility for
<br />detention slorage will reduce Ilow. in downstream sewers to below estiIrulted capacities.
<br />Wilhout,eeured'toragethesesewersdonOlhaveadcquatecapacilyfor2-yearrutlOfL
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<br />To minimize street Ilooding ;t i.. r.commended that 30.in,h 'torm >cwefS be ooo,trUcll:<.I
<br />aloug Mountain View Avonu. and 151h Avenue between ushley Street.nd Oligarchy Ditch.
<br />11 i, proposed lh.t. wastew.y and overflow ch:mncl from Oligarchy Ditch to St. Vrain Creek
<br />be constructed due <outh from ocor where IheditCh crossesSugarmiU Rood. The chanocl
<br />.<houJd be ,ized to carry 0 minimum of 900 crs and will accommodate Ihe computcd 2-ycar
<br />Oligarchy Ditch nOws M well as local rulloffat thi, locmion. The Z.year""'l 5-}'c", runoff
<br />here in Oligarchy Ditch i, cstimated to be bb5 and lUS cr,. respeclively. assuming Ihe
<br />upstream d,lCh has capacity to con"cy 11lnoff to this poim, The cstimatedeapacity of the
<br />Higllway 11geuh'cn n""rthis location is8SlJcf.. Thcpropo5-Cdchanncl size will permit
<br />ahllo,t all runoff from minor "arm, to be removed from the ditch downstream of Highway
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<br />119.
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<br />D.
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<br />MCINTOSH l.AKE RAS!)oI
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<br />The IIX).year improvements for thi_, ha.,;n ioclude ,ecuring flood slO;age capacily in Mclnto,h Lake
<br />ond cnnstroct;n~ on overflow eh~nncl from Ihe I~ke spillw~v 10 St. Vr~in Creek (see Dra",i,,~. 7 ~"d
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<br />25
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<br />9), The,e facilitie, would intercept upper-basin runoff. diven il 10 the creek ,nd e~c1udc ,uch runolY
<br />from impacting drainage systems within the MSA Approxim~'el}' 190 acre-feet of flood storage is
<br />nc"-ded~t the IJke loprodu"" a 760cfs 'pillway rckase. The overflow channel would be sized for
<br />this release plus flows from thc We'l Howr Basin. diseu5sed in the rn:~t seclion. and would be
<br />aligned parallel to Airport Road to St. Vrain Creek, If such detention capadty cannot be =UR-d J
<br />le,se, amount could be used and l1\c o>erflow chao"ol sizo increased os necess.ry to accommodate
<br />a higher re1ease rate.
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<br />I'or 2-;'e~r runoff mnnagemen!. an agreement with tho operator of the LQngmont Equalilcr Pond
<br />should be secnroo such that the present use ofthc pond for stormwater detention will continue,
<br />Elsewhere in this basin. wilhin the MSA. local .ystem.' should be appropriately designed 10 convcy
<br />runoff 10 the lake.
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<br />WEST HOVER RA~IN
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<br />Upper BasinllPA Improvements
<br />AllhcprcSentlimc. ilnppearsthatruoofffrom the upper halin is intCteepled and detained
<br />a! Burch Lake duc 10 spillway/n.-scrvoir routil\!l" It is recommendcdthat this Slorago bencfit
<br />be secured such that cominuoo func,ion of the lake as a Jctcntion facility can bereliooupon
<br />to~lIenuatedownMream flood peaks,
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<br />The lOO-year runolT from areas upslream oflhe MSA should be precluded from entering 1ll<:
<br />MS." thrOllgh di,'ersion 10 Sl. Vrain Cteek (""c Drawint: S), Thi, diversion COlJld be
<br />accomplished through a eh~nnel just we,! of Airport Ro~d as described for the Mclmosh
<br />i...ke Basin in the preceding ""'tion. In addition to the Mcintosh L1ke ovcrflows, the
<br />channel would need to c""vey a!->out \lflO cr. from the We't H,wer R..in if BUfCh Lake
<br />dcteOlionis,ccurcd, Without Burch Lake detemion, abOllt ISOOcf,capaeity for West Hover
<br />rolloffwotlfdbe re'luncd
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<br />MSA Improvement.
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