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Shaw Environmental, Inc. <br />NORTH COUNTY RECYCLING CENTER AND SANITARY LANDFILL <br />CHECK OF THE ADEQUACY OF EXISTING GEOCOMPOSITE DRAIN ON THE SIDESLOPES OF MODULE 4 <br />Required: Verify if the flow capacity of existing geocomposite drain on the sideslopes of <br />Module 4 is adequate, based on the recorded peak flow between 2005 and 2007 <br />References: 1. Koerner, R.M., (1998). Designing with Geosynthelics, Fourth Edition. <br />2. Geosynthetic Research Institute. (2001). GRI Standard - GC8 <br />3. Giroud, J.P., Zomberg, J.G., and Zhao, A. (2000). "Hydraulic Design of Geosynthetic and <br />Granular Liquid Collection Layers", Geosynthetic International, Vol. 7, Nos. 4-5. <br />Design Data: <br />Infiltration rate in to the geocomposite drain based on <br />Module 4 peak pumping rate q = 1000 gpad <br />or <br />Geocomposte slope <br />Slope length perpendicular to the pipe, measured <br />horizontally from pipe to the crest of slope <br />Effective slope length in the direction of flow, <br />measured horizontally <br />Maximum waste height <br />Waste unit weight <br />Maximum normal stress <br />Geocomposite thickness tg = <br />Thickness of the liquid collection layer for geocomposite tcLc = <br />0.0368 inch/day <br />1.08E-08 m/sec <br />33 <br />% <br />0.319 radians <br />180 <br />it <br />180 ft <br />54.9 m <br />241 ft <br />90 pcf <br />21690 psf <br />260.00 mil <br />0.0066 m <br />Measured minimum index transmissivity at 16,900 psf <br />normal stress and hydraulic gradient of 0.33 <br />015 = <br />6.94E-04 m`/sec <br />Reduction Factors: <br />Note: <br />(1) The values of RF,,,, RF,„ RF,,, and RFy, below may be <br />selected based Koerner (1998) <br />(2) The value of RF,, can also be determined using GRI Standard GC8 <br />Reduction factor for intrusion due to elastic deformation <br />RF;r, = <br />1.75 <br />Reduction factor for creep deformation <br />RF,r = <br />1.70 <br />Reduction factor for chemical clogging/precipitation <br />RFS = <br />1.75 <br />Reduction factor for biological clogging <br />RFtc = <br />2.00 <br />Total reduction factor (TRF) <br />TRF = RFI„ x RFS, x RFa x RFw <br />TSF = <br />10.4 <br />Calculations: <br />Total flow at the toe of geocomposite, <br />q= e x L <br />q= <br />5.94E-07 M2 /sec <br />Required transmissivity (without TRF and a global factor of safety), <br />0 = q/sin 0 <br />0 = <br />1.90E-06 m2/sec <br />Required transmissivity (without a global factor of safety) <br />815 = 0 x TRF. <br />0t5 = <br />2.0E-05 m2 /sec <br />Check using Giroud et al. (2000) equation: <br />els = TRF eL= 2.0E-05 m2/sec <br />sin Q + t CL / I L Cos 2,8 <br />Global factor of safety = FS = 35.2 <br />Factor of8aVety Is a 2, therefore, Acceptable <br />N:IGEOTECHNICALWCRC&SL-2007\GeonetTransmissivity0odule4WCRC&SL_Module4_Geonet t000gpad.xis <br />Page 1 of 1 <br />