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The GSE Drainage Design Manual Chapter 4—Design Methods And Concepts <br /> where a q = required hydraulic transmissivity for geonet or geocomposites (m3/sec per in <br /> width); ,u$., = dynamic viscosity of landfill gas (kPa); #,,,.t, = dynamic viscosity of water <br /> (kPa); X.,=unit weight of water(kg/m3);and y,.=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, 19981. <br /> DENSITY UNIT WEIGHT OYNAMiC VISCOSITY KINEMATIC VISCOS <br /> v�ul <br /> slugtft kg/m uvft N/m Poise s/R N-stm els 'I/s <br /> or or <br /> s-ft s-m <br /> Water 1.94E+ 9.99E+02 6.24E+01 9.80E+ 1.01E-0 212E-05 1.01 E-03 1.09E-05 1.01 E <br /> Air 2.34E-03 1.20E+00 7.53E-02 1.18E+01 1.80E-04 3.78E-07 1.79E-05 1.62E-041 1.48E <br /> CO2 3.55E-031.83E 1.14E-01 1.79E+01 1.50E 315E-07 1.50E-05 8.88E-05 8.21 E <br /> Methane 1.29E-03 6:66E-0 4.16E-02 6.54E 1.10E-04 231E-07 1.10P-05 1.79E-04 1.65E <br /> LFG 55% 2.53E-03 1.31E 6.15E-02 1.28E+01 1.32E1- <br /> Notes: <br /> .77E-07 1.32E-05 1.09E-04 1.01E <br /> CO2,45% <br /> CH4 <br /> (1)Values for LFI:;(landfill 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 different than other landfills. <br /> (2)Values are at standard temperature and pressure. <br /> 18"Vegetative Cover <br /> Geocomposite Drain <br /> „ Geomembrane <br /> 18 Soil BaLayer <br /> mer <br /> Geocornposite for <br /> Gas Venting and <br /> Seep Collection <br /> Waste and Interim Cover Sod <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 />