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<br />MEMORY TRANSMISSION REPORT <br /> <br />PACE :001 <br />T11E :MAY-19-O1 10:59AM <br />TEL NUMBERI: +13039663567 <br />NAME :Colorado Division of Minerals 6 Geolosy <br />FILE NUMBER 169 <br />DATE MAY-IB 10:50AM <br />TO $19706354012 <br />DOCUMENT PAGES 006 <br />START TIME MAY-16 10:50AM <br />END TIME NAY-18 10:59AM <br />SENT PACES 006 <br />STATUS ON <br />FILE NUMBER :189 *** SUCCESSFUL TX NOTICE *** <br />STATE OF COLORADO <br />OIV15rON OF MINERALS ANO GlOLOGY <br />o.rs,,,nv~a or N......i Rv.o..rr.. .. .___ _.. <br />1 x 1.1 sburmun so. amm ]1 s <br />o......r. Col,r.oalo eo]ox <br />(-su3l e9]•e 106 <br />May 17, 2001 <br />Rocky lioRa<hnefdsr <br />Peal-IC pa% No[a >.>1 Oa. / ~ <br />1b - F.em <br />Cu/apl G. <br />^^°^. 3 <br />p ,J <br />M I H~ R A L S <br />G E O L O G Y <br />~aectr. n derv <br />Plane Band R Gravel LLC c1T`A °~• <br />P.O. BOX 1 BO . ~°~ i.. oi.~.e`rle <br />Littlexan, CO 80306 .~ •. [.,.. <br />o~.~n... u~.r..,... <br />AE. Rlverbaatc and Ptt Blope Armorlpg Proposal, Tacbvfcal Revlelvn <br />to S@aH Mtoa Bverioe 113 Acclamation Fermlt Appticattee, Platte <br />YWry 9aod sad Gravel. Fits Ne_ M-2000-13g <br />Dear Mr. Hott4chneider, <br />Plane Smd S Gravel r r r has provided a technical .avision (TR) to A,rN.r .setae. ooneerne wiN erosion <br />povenxial through the gravel pit mining yells during a large flood event. The TR includes an Illustration of <br />locations that the Applicant has determined to be smsitive area with Ne potendel For ax<esslve erovlon. The TR <br />includea a proposal sad designs to rtabillze certain of these potantinlly emsidvv erase by srmoring through xhc <br />placemmx of riprnp. The TR also includes cost vas:metes for the placemene oP rlprap and a description of Ne <br />tamirag of riprnp :namllation relative to Ne sequence of «csvaxion in the gravel pits. The Division's rwisw of the <br />TR is broken out into four seecione in Nis mvmoratldum as Tollows_ <br />. The determination of loearions that may be cubJ act to erosion during a large Flood. <br />. The spee:Tiva[lon and drawings that will gwero rhv sizing and plaooment of rlprap. <br />. The vstimaced cos[ w Purchase and take delivery oEriPrsP chat meets ePael£catloq and to Ins[ell Ne riPr'aP In <br />n<cordm<s with designs and drawings approved by Ne Division. <br />a The cimemble for rlprap inrtallation, in particular Ne inrtallst:on of No riverbank rlprap. <br />Ae s radar, Ns purpose of the flood c ntroVmi<igscion plan : e Ne potvnelal for exeasa:ve soouring <br />arrd erosion of yix slopes end of berme protesting ericl<al strueturea such urges pipelines, end of offaim impaess <br />due xo sedimenmtion or realignment of Ne existing river cllanneL <br />Rlp ptocerlonr <br />In order m proven[ excessive erosion, area Nat may be subject to scour during a flood should be armored. To <br />Idenxity axes of scour, the depN and velocity of Floodwamrs should be estimamd and Ne gradation of Ne soil and <br />abseil (sand and gravel) may by c - ad along wiN vagemtion chaaacterirt:cs co detertnlna if Ne waive power <br />oP the Flood will <uc into Ne vegexat:on end soil. Plecamanx of larger and heavier ma[er ial (r:pmp), Nsc cannot be <br />I1Rvd and moved by floodwamr, will prevent erosion and down cutting :n locations IdentlFled to be prone ro scour. <br />There are a number of published c mpumtional methods available to demrtnina Ne sizing and grvdaxlon of rlprap <br />required m armor agalnrt erosive Slows of different velaeitiee. <br />Depth and velocity of Floodwater :neraues exponencislly in flood w of inetaas:r[gly lower probability of <br />The ran-permnt mnuel cltan<s flood (the so-called ten-year flood) resale :n a substanc:ally lower <br />flow, depN, end veldclry Nan a o o-Percen[ an al chance flood (thy 100-year remm per ode [xt). Designs <br />armoring against sroa:on during a 100-year flood would most likely fail during s much Iarga, but longer rctum <br />