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v <br />As noted above, the maximum grain size of the drainage layer is assumed to be 9.5 mm. <br />Since the gravel particles are next to each other in a layer and not isolated, the effective <br />protrusion height can be assumed to be half the maximum gravel size; i.e., <br />H = 0.5 x 9.5 mm = 4.75 mm = 0.000475 m <br />Although rounded gravel was specified, to be conservative, assume that the gravel used is <br />sub -rounded. For sub -rounded stone, <br />MFS = 0.5 <br />For packed stones, <br />MFPD = 0.5 <br />Because waste to be placed above the geotextile is, deep, maximum arching is anticipated, <br />therefore, <br />MFA = 0.25 <br />The FSCR depends on the mass per unit area of the geotextile. There is no geotextile <br />cushion, but the protrusion size is very small; assume a conservative value of 2, <br />FCR = 2 <br />Assume, a factor of safety of 1.3 for chemical and biological degradation, <br />FCBD = 1.3 <br />Substituting the above values in eq. 1, <br />or <br />or <br />3,300 = 50+0.00045 M 1 I F1 <br />(0.000475)2 11(0.5) (0.5) (0.25) (1.3) (2) <br />3,300 = 307 + (12,274)M <br />M = (3,300-307)/12,274 = 0.244 g/m2 or 0.0072 oz/yd2 <br />3.0 Conclusions <br />Since the required M is practically equal to zero, the calculations show that the <br />geomembrane can support the proposed 240 feet of waste without a geotextile cushion. <br />Page 2 of 2 <br />N.IGEOTECHNICALWCRC&SL.20071Punture-ResistanceWodules 5-II1Rounded GraveLdoc <br />