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MOUND DESIGN WORKSHEET <br />(For Flows up to 1200 gpd) <br />A FLOW <br />Estimated ')~0 gpd <br />or measured -X 1.5 = -gpd. <br />B. SEPTIC TANK UQUID VOLUMES <br />?c-/oo D c_~,) C.<i:y. gallons :;,_ -/00<.:J ,v1•:,--<i1 '1--1 \., (_ q'v--p I -/oOO~--i\ j <br />C. SOILS (refer to site evaluation) , 1 <br />1. Depth to restricting layer = ~o -ro .~o inches <br />2. Depth of percolation tests = l ii II inches <br />3. Percolation rate ;;__ .°7 mpi <br />4. Land slope °' % <br />D. ROCK LA YER DThffiNSIONS <br />1. <br />2. <br />3. <br />Multiply flow rate by 0.83 to obtain required area of rock <br />layer: Ax 0.83 = <br />1-.S"u . gpd x 0.83 sq. ft./ gpd =~sq. ft. <br />Select width of rock layer (10 feet or less) = __,_/......:o'----ft. <br />Length of rock layer = area+ width = <br />Ce :i_?., sq. ft. + ) o ft. = '4, :)__ ft. <br />E. ROCK VOLUME <br />1. Multiply rock area by rock depth to get cubic feet of rock; <br />~sq. ft. x~ft. =~cu.ft. <br />2. Divide cu. ft. by 27 cu. ft./ cu. yd. to get cubic yards; <br />~cu.ft. + 27 =~cu. yd. <br />3. Multiply cubic yards by 1.4 to get weight of rock in tons; <br />~ cu. yd. x 1.4 ton/ cu. yd. = ~ tons. <br />F. ADSORPTION WIDTH L..o i-1 )Yl <br />1. Percolation rate in top 12 inches of soil is ~ mpi <br />Estimated Sewage Aow in Gallons per Day (gpd) <br />Number <br />of Type! <br />Bedroom, <br />Type II Type III Type IV <br />2 300 225 180 6()'l, <br />3 450 300 218 of <br />4 600 375 256 the <br />values 5 750 450 294 in <br />6 900 525 332 the <br />7 1050 600 370 other <br />colu.mru 8 1200 675 408 <br />Number ---~-Cap,city,.·u.b <br />of G..,.... <br />Bedrooms c..,-;,y ~ <br />C,,.U.-) (pl.lao,) <br />2 or less 750 1.125 <br />3 or4 1.000 1.500 <br />5 or6 1.500 2.250 <br />7 or 8 2.000 3,000 <br />ove.-9 See fig. C-6 (x 1.5) <br />Rock Bed <br />Length <br />Absorption Width Si.zing Table <br />PercoLltion Rabe c..n~ Ratio ol <br />Soil Texture po-d.oy n>dbed <br />Minute, per inch po-,qu...-. w'idth to <br />. (mpu r .... -~~ <br />2. Select allowable soil loading rate from table; <br />, (.,. o gpd/ ft2 <br />Faster than 0.1 K:oarse Sand 1.20 1.00 <br />3. Calculate adsorption width ratio by dividing rock layer <br />loading rate of 1.20 gpd/ft2 by allowable soil loading rate; <br />1.20 gpd/ft2+ ~gpd/ft2 = :) .oo . <br />4. Multiply adsorption width ratio by rock layer width to get <br />required adsorption width; <br />:J.o O X ....l!:2___ ft = ~(9, D ft <br />0.1 to5 Sand 1.20 1.00 <br />0.1 to5 Fine Sand-0.60 2.00 <br />6 to 15 Sandy Loam 0.79 1.52 <br />..16..to..30 Loam _d[6ID 2.00 <br />31 to 45 Silt Loam 050 2.40 <br />46 to 60 Clat Loam 0.45 2.67 <br />61 tO 120 lay 0.24 5.00 <br />Slower than 120 Clay --- <br />•• Soil having~ or more of fine or very fine sand. <br />I