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The GSE DrainageDesign Manual <br />4"3 AtrIowuble Wnnsmissivity <br />Chapter 4 -Methods And Concopts <br />{4.22) <br />with thar <br />" The required <br />the three va.lues. <br />0o,r = 0o = -na 'La 'to- *- <br />r[',-T*) <br />The minimurn required transmissivity computed abtlve shourcr beealeulated based on reakage rate and a1v 3ifmum reguratoly require,transmissivity of the reak detection rayer shourd thd b; ** on dre rargest <br />zj\ <br />transmissivity that <br />is unique for a given shess andgradient; therefoire, fhe laboratory testing must be perfonireC at the sarme and gradient"A'lternatively, if higher gradient is used for testing ttren attopi,able transmissi ity value at a lowergradient oan be computed based on the empirical relati presented Section 2.3. The <br />to the required <br />allowable transrnissivity will inolude an increasecl <br />iTr:t1Y:jy::::9:: ro acoounr for: .(i) a design factor q:f safety; and^fii)changesdue to environm,Ental effects on the in-place <br />drainage is apptiied to aocount for uncerraintie-s in d;&il;;"-"d?rrrpa*kor anrl a*Ila. €a ^a^.-- 4r- -! -- - - 6 | - <br />The design of safety for <br />properties, <br />the flow capacity <br />ffansmissivity as shown below" <br />Its in the allo'arable <br />4rro* = ?nq. FS D (4.23) <br />where: <br />The allowable transriaissivity inoluded in the specificationir is the min <br />H::1 ":: H:"::yy*l":lr:^Ii: .11:.*.u0," rransmissivirv is un iluc <br />aor b* = nnin in'um allowable transmissivity of geocomposite (m2lsec), <br />k:::yft$:ryy:iyiy F, a site as exprlinea i" s"!ti.,li + .i t^rrr"*F,9o: overall factor of safety for drainage (dimensio;;rsi. <br />Environmental factors such as biological clogging, chemi -term crerep of <br />geocompositer. To <br />reduction faotors for each component. The magnituae oi"a"L reduetion <br />:::il-:^:'_ g:i::' rlln" tl .should reflect a correcrion rhat provides <br />further using <br />equal to or greater than l) should reflect a correction <br />(which should beurq' r,' uuuultr renegl a correction that provides a <br />trITfTj:'jT:T: ul :h"yllyt pe innared to a rarger uuiu* ,o account <br />estimate oli the <br />ll':l::^fl:*lrJ,"l accounted tlin the factor oirurJrv. Clte a,owabte tran <br />uncertainty, slince <br />in Equation 4.24 trelow (see also GRI procedure GCg): <br />issivity is shown <br />0^ron = 9r"q . F,SD . R%n . ft4" . R4c <br />where: <br />daro* - minimum allowabre transmissivify of geocomposi{es or geonet (m2 <br />Page 4-13 <br />(4.24")