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U <br />C <br />The GSE Drainage Design Manual <br />Chapter 4 — Design Methods And Concepts <br />where a q = required hydraulic transmissivity for geonet or geocomposites (m3/sec per in <br />width); ,ug, = dynamic viscosity of landfill gas (kPa); = dynamic viscosity of water <br />(kPa);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 />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 Butte case <br />history, which may be different than other landfills. <br />(2) Values are at standard temperature and pressure. <br />18 " Vegetative <br />18 Soil Barrier Layer <br />(k < 10-5 cm/s) I <br />0 <br />Perforated PE Underdrain Pipe to <br />Collect Seepage Underlain by <br />Geomembrane Rub Sheet <br />Geocomposite Drain <br />Geomembrane <br />Geocomposite for <br />Gas Venting and <br />Seep Collection <br />and Interim Cover Soil <br />verroraceta Laterai HE Pipe at <br />150 O.C. to Vent Gas and Drain Seeps <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 />DENSITY <br />UNIT WEIGHT <br />DYNAMIC VISCOSITY <br />KINEMATIC VISCOSITY <br />v= r <br />slug/ft kg/m <br />Ib/ft <br />N/m <br />poise lb-s/ft N-s/m <br />ft /s <br />m /s <br />9/(cm-s) or or <br />Islugl(s-ft)k <br />s -m <br />Water <br />1.94E+00 9.99E+02 <br />6.24E+01 <br />9.80E+03 <br />1.01 E-02 2.12E-05 1.01E-03 <br />1.09E-05 <br />1.01E-06 <br />Air <br />2.34E-03 1.20E+00 <br />7.53E-02 <br />1.18E+01 <br />1.80E-04 3.78E-07 1.79E-05 <br />1.62E-04 <br />1.48E-05 <br />CO2 <br />3.55E-03 1.83E <br />1.14E-01 <br />1.79E+01 <br />1.50E 04 3.15E-07 1.50E-05 <br />8.88E-05 <br />8.21 E-06 <br />Methane <br />1.29E-03 6.66E-01 <br />4.16E-02 <br />6.54E+00 <br />1.10E-04 2.31E-07 1.10E-05 <br />1.79E-04 <br />1.65E-05 <br />LFG 55% <br />2.53E -031.31E+00 <br />8.15E -021.28E+01 <br />1.32E-04 2.77E-07 1.32E-05 <br />1.09E-04 <br />1.01E-05 <br />CO2, 450A <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 Butte case <br />history, which may be different than other landfills. <br />(2) Values are at standard temperature and pressure. <br />18 " Vegetative <br />18 Soil Barrier Layer <br />(k < 10-5 cm/s) I <br />0 <br />Perforated PE Underdrain Pipe to <br />Collect Seepage Underlain by <br />Geomembrane Rub Sheet <br />Geocomposite Drain <br />Geomembrane <br />Geocomposite for <br />Gas Venting and <br />Seep Collection <br />and Interim Cover Soil <br />verroraceta Laterai HE Pipe at <br />150 O.C. to Vent Gas and Drain Seeps <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 />