BEsT MANAGEMENT PRACTICEs HANDbooK - Tahoe BMP

FOR NON-BREAKING WAVES:W50,lbs1.27HKRR s wtoe,unbroken,feet13m3(Equation 16.22)with K RR = 2.5 (CEM VI-5-86)If both cases were required to be considered, use the higher of these weights.Grade the rock on the armor layer to be no wider than:W max = 4.0 W 50,lb and W min = 0.125 W 50,lb (Equation 16.23)The nominal rock diameter is:D13W50,lb 50,ft s (Equation 16.24)• The armor layer should be a minimum 2D50 thick.• The filter layer should have a gradation corresponding to 10% by weight ofthe armor layer. The filter layer thickness should be a minimum two stonesthick, and in any case no less than 1 foot thick.• Geotextile should normally be placed under the filter layer. If the fabricbegins to become exposed or frayed, repairs must be made promptly.The empirical coefficient in Hudson’s Equation, KRR, is based on laboratorytests and varies to include the effect of stone angularity or roundness, numberof layers of armor stone, distribution of individual stone sizes about the mediansize, and interlocking characteristics. The values suggested here, KRR = 2.2 andKRR = 2.5 are for a layer of rough-angular quarry-stone at least two stonesthick. The stones have a gradation of weights that varies between 0.125 W50