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/ ,�DiVit.-1 Aft./di,Ei✓ . / .•J BR E-20 MOUND DESIGN PROCEDURE (Continued) . (For Flows up to 1200 gpd) ._. . . - ... • G.3. Calculate basal width ratio H.2.f. Multiply dike multiplier by by dividing rock layer 2 downslope mound height to get loading rate of 1. 20 gpd/ft downslope dike width; by allowable soil loading y 76 x..3, 9 = /2, 6 f t rate; 1. 20 gpd/f t2 -0,`1$gpd/f t2 =2. 67 g. Compare the values of step H. 1 Check this value on page E-16. and step 11. 2•f. Select the greater of the two values as 4. Multiply basal width ratio by the downslope dike width; rock layer width to get ler- 6 feet required basal width; 2, 67 x /G ft Z6, 7ft h. Calculate upslope dike width 3: using upslope' mound height H. Downslope Dike Widthand upslope diko_,multiplier from page E-18• 1 . If landslope is 3% or more, Z. 6.' x 3.,� = ' 9, Y_f t i. Total mound width is the sum subtract rock layer width from basal width to obtain of upslope dike width plus rock minimum downslope dike toe width layer width" plus` �3ownslope dike 26. 7 ft - /p ft =./6"..-7ft width; Y ft +" /o ft -F/l 6ft =.3p Oft nii:1 2. Calculate mound height at edge 3. If landslope is 2.9 percent or of rock layer on downslope side; less, basal width includes both ' • a . Determine depth of clean sand 4-114‘-6: 1"/6" ' fill at upslope edge of rock the upslope and downslope dike '4l.F, s6'- s layer: ,/ 5 feet widths. "771...147 b. Multiply rock layer width by a. Calculate downslope dike width landslope to determine drop using steps }1.2.a . through in elevation; 11.2.f; feet /0x y % - 100 = 0. 7f t b. Calculate upslope dike width c. Add drop in elevation to depth using upslope mound height and • dike multiplier from Page E-18; of clean sand at upslope edge of rock layer to get depth of x ft = ft clean sand at downslope edge , c. Add downslope—dike width. to • of rock layer. upslope dike width to rock 0, y f t + /. 5 f t = I. 9 f t layer width to get total mound d. Add depth of clean sand at down- width; slope edge to depth of rock ft + . ft + ft = ft layer to depth of soil backfill --- --- to get mound height at downslope d. Compare total mound width to required basal widthfrom step edge of rock layer; / G,..4 .9 f t +0.75 f t +425'f t =.3 9 f t If total mound width is f greater than' required basal e. Enter table on page E-18 with width, use calculated dike landslope and downsldpe dike ' widths. If required basal ratio. Select dike multiplier width is greater than total of y 7.6 • y:/ rea,,e mound width, increase downslope dike width.