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MOUND DESIGN PROCEDURE (Continued) <br />(Fir Flows up to 1200 gpd) <br />G.3. Calculate basal width ratio <br />by dividing rock layer <br />loading rate of 1.20 gpd/ft2 <br />by allowable soil loading <br />rate; <br />1.20 gpd/f t2 - O SgPd/f t2 = j•�7 <br />Check this value on page E-16. <br />4. Multiply basal width ratio by <br />rock layer width to get <br />required basal width; <br />'?.`1 x /o ft - 26.7ft <br />H. Downslope Dike Width <br />1. <br />If landslope is 3% or more, <br />subtract rock layer width <br />from basal width to obtain <br />minimum downslope dike toe width <br />ft - ft - ft <br />Calculate mound height at edge <br />of rock layer on downslope side; <br />a. Determine depth of clean sand <br />fill at upslope edge of rock <br />layer: feet <br />b. Multiply rock layer width by <br />landslope to determine drop <br />in elevation; <br />x % 100 - ft <br />c. Add drop in elevation to depth <br />of clean sand at upslope edge <br />of rock layer to get depth of <br />clean sand at downslope edge <br />of rock layer. <br />_ft + ft ft <br />d. `Add depth of clean sand at down - <br />slope edge to depth of rock <br />layer to depth of soil backfill <br />to get mound height at downslope <br />edge of rock layer; <br />ft + ft + ft ft <br />e. Enter table on page E-18 with <br />landslope and downslope dike <br />ratio. Select dike multiplier <br />of <br />E- 20 <br />11.2.f. Multiply dike multiplier by <br />downslope mound height to get <br />downslope dike width; <br />x - ft <br />g. Compare the values of step 11.1 <br />and step H.2.f. Select the <br />greater of the two values as <br />the downslope dike width; <br />feet <br />h. Calculate upslope dike width <br />using upslope mound height <br />and upslope dike multiplier <br />from page E-18; ft <br />'C - <br />i. Total mound width is the sum <br />of upslope dike width plus rock <br />layer width plus downslope dike <br />width; <br />ft + ft ft = ft <br />3. If landslope is 2 percent or <br />less, basal width includes both <br />the upslope and downslope dike <br />widths. <br />a. Calculate downslope dike width <br />using steps H.2.a. through <br />H.2.f; ; feet <br />b. Calculate upslope dike width Y. <br />using upslope mound height and <br />dike multiplier from Page E-18; <br />.? D X.747ft = .);5 ft <br />Add downslope dike width to <br />upslope dike width to rock <br />layer width to get total mound <br />width; <br />le!Zft +8_Sft + ID ft =2Y.7ft <br />d. Compare total mound width to <br />required basal width from step <br />G.4. If total mound width is <br />greater than required basal <br />width, use calculated dike <br />widths. If required basal <br />width is greater than total <br />mound width, increase downslope <br />dike width. `/lF 2f. 7 <br />