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' The GSE Drainage Design Manual Chapter 4—Design Methods And Concepts <br /> where Og = required hydraulic transmissivity for geonet or geocomposites (m3/sec per m <br /> width); /4,,, = dynamic viscosity of landfill gas (kPa); /,.,, = dynamic viscosity of water <br /> (kPa); ? sae, =unit weight of water(kg/m3);and yg,.=unit weight of gas(kg/m3). . <br /> Table 4.3 provides density and viscosity values for various fluids for use in Equation 4.12. <br /> Again we note that a very significant side benefit of providing a gas collection layer under the <br /> final cover is that it will also serve to collect sideslope seeps.The seeps would be collected at the <br /> toe of the geocomposite gas collection layer,as illustrated in Figure 4.5. <br /> Table 4.3 Density and viscosity of various fluids[Thiel, 1998]. <br /> DENSrTY UNIT WEIGHT DYNAMIC VISCOSITY KMEMATIC VISCOS <br /> Slug/ft kg/m ibift N/m Poise !b-s/Ft N-s/m els m% <br /> 9/(cm-s) or or <br /> s-ft I kafts-ml <br /> Water 1.94E 9.99E+ - 6.24E+01 %eOE+03 1.01E-02 Z12E 1.01E-03 1.09E-05 1.01£ <br /> Air 2.34£-03 1.20E+00 7.53E-02 1.18E+01 -I-BOE 3.78E-07 1.78E-OS 1.62E-04 1.48E-05 <br /> CO2 3.55E-031.83E 1.14E-011.78E+01 1.50E 3.15E-07 1.50E-05 8.88E-05 8.21E <br /> Methane 1.29E-03 6.66E-01 4.16E-02 6.54E 1.1�-04 231E-07 1.10 -05 1.79E-04 1.65E-05 <br /> LFG 55% 2.53E-03 1.31E 8.16E-02 1.28E+41 1.32E-04 2.77E-07.1.32E-05 1.09E-04 1.01 E-0 <br /> CO2,45% <br /> Ctt4 <br /> Notes:(1)Values for LFG(landtitl gas)were assumed to be Prorated as 55%properties of carbon dioxide,and <br /> 45%Properties of methane. This ratio was used to match the LFG characteristics for the Coffin Butte case <br /> history,which may be ditrerent than other landfills. • <br /> (2)Values are at standard temperature and pressure. <br /> 18"Vegetative Cover <br /> Geocomposite Drain <br /> ...,ht i'�7?`:v. •'root`-e' �''%-b`'=w:r`''� _ <br /> ;s-'°•*-r':...`z..�•y;=;,`:.•'..ru^S:r.�::.=A.�`::Y.:{e�•.<'-,".<�eYr-.:�g'.-.;Y:j:Kw,..;.,.:•,�,..:,:;7:==�,' <br /> $i:i`S•}:•.:rt•'T:wM1:'"4't.•,:3Y'�f< <br /> �x�.r•P,.•':'-�•j:_�/•o'9cia <br /> Geomembrane <br /> . r fi18 Soil Barrier Layer <br /> (k<10-5 crNs) <br /> ::• ,._. r:?:��:Vie•. =M::��-�>t3.o''ti.."si� <br /> Geocomposite for <br /> Gas Venting and <br /> Seep Collection <br /> .' <br /> i <br /> Waste and Interim Cover Soil <br /> Perforated PE Underdrain Pipe to Perforated Lateral PE Pipe at <br /> Collect Seepage Underlain by 150 O.C.to Vent Gas and Drain Seeps <br /> Geomembrane Rub Sheet <br /> Figure 4.5 Seep collection at toe of gas collection layer under final cover system. <br /> 4.2.3 Landfill Leachate Collection and Removal System <br /> Leachate impingement into the leachate collection layer is buffered due to relatively large • <br /> thickness of overlying waste and soil material making the effect of precipitation much more <br /> Page 4-7 <br />