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The GSE Drainage Design Manual Chapter 4—Design Methods And Concepts <br /> where aey = required hydraulic transmissivity for geonet or geocomposites (M3/sec per in <br /> width); ,u$ = dynamic viscosity of landfill gas (kPa); ,cc,��er = dynamic viscosity of water <br /> (kPa); y mer=unit weight of water(kg/m); 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, 1998]. <br /> DENSITY UNIT WEIGHT DYNAMIC VISCOSITY KINEMATIC VISCOS <br /> slug/ft kg/m Ib/ft N/m poise lb-s/ftN-s/m ft/s m/s <br /> 9/(cm-s) or or <br /> slu s-ft k s-m <br /> Water 1.94E+ 9.99E+02 6.24E+01 9.80E+03 1.01 E-0l 2.12E-05 1.01E-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-04 1.48E-05 <br /> CO2 3.55E-031.83E+ 1.14E-01 1.79E+01 1.50E-04 3.15E-07 1.50E-05 8.88E-05 8.21E-06 <br /> Methane 1.29E-03 6.66E-01 4.16E-02 6.54E+00 1.10E-04 2.31E-07 1.10 -05 1.79E-Q4 1.65E-05 <br /> LFG 55% 2.53E-03 1.31 E+00 6.15E-02 1.28E+01 1.32E-04 2.77E-07 1.32E-05 1.09E-04 1.01E-0 <br /> CO2,45% <br /> CH4 . <br /> Notes:(1)Values for LFG(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"e case <br /> history,which may be different than other landfills. <br /> (2)Values are at standard temperature and pressure. <br /> 18"Vegetative Cover <br /> Geocomp osite Drain <br /> k. <br /> v F <br /> :::. y�:a�•� "--E-- Geomembrane <br /> 18 <br /> Soil Barrier Layer <br /> y . <br /> k< 10-5 cm/s) <br /> - <br /> .......... <br /> Geocom osite for <br /> Gas Venting and <br /> / �.::• <br /> �j/�����o• Seep Collection <br /> o � <br /> J. s 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 />