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C <br />Shaw Environmental, Inc. <br />NORTH COUNTY RECYCLING CENTER AND SANITARY LANDFILL, MODULE 3 <br />CHECK OF EXISTING LEACHATE COLLECTION PIPES <br />USING THE IMPROVED PIPE LOADING CALCULATION <br />B. Loading on the Pipe <br />[7 <br />slots/perforations: <br />width or diameter d =1 0.25 inch <br />number of slots/row/ft n = 1 <br />pipe modulus of elasticity <br />Initial Ep = 120000 psi <br />Long-term (50 year) 22000 psi <br />Compressive yield strength <br />Initial PA = 3000 psi <br />Long-term (50 year) 1440 psi <br />The loading based on the maximum waste height is computed below: <br />2.0 ft. final cover @ 115 pcf 230 psf <br />1.0 ft. intrm cover @ 110 pcf 110 psf <br />162.0 ft. solid waste @ 80 pcf 12,960 psf. <br />13,300 psf <br />6 = 92.4 psi <br />Total load with correction for pipe slots/perforations, <br />6 <br />6i = <br />(I — n.d/12) <br />a, = 94.3 psi <br />C. Bedding Material Properties <br />Construction plans show that a sand bedding was used below the pipes. <br />deflection lag factor Lt = i <br />bedding constant K = 0.11 <br />modulus of soil reaction E, = see below <br />Replace E, by M,. (based on McGrath, 1998a) <br />Based on McGrath (I 998a), replace modulus of soil reaction (Es) with stress <br />dependent constrained modulus (Ms). The figure from Koragappa (2005) <br />presented on next page shows variation of M, with 6, for typical bedding materials. <br />N:\GEOTECHNICA L\NCRC&SL-2007\Pipe- Loadine\Module 3\Module3_41nchPipe_ImprovedMethod_I65ft.xls <br />Page 2 of 6 <br />