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MOlJND DESIGN WORKSHEET <br />(For Flows up to 1200 gpd) <br />A. FLOW Estirna1ed Sewage Flow in Gallons per Day (gpd) <br />Estimated 0{·: gpd Number <br />of Type! Type II Type Ill or measured -X 1.5 = -gpd. Bedroorru <br />2 300 225 180 <br />3 450 300 218 B. SEPTIC TANK UQlJID VOLlJlviES 4 600 375 256 <br />5 750 450 294 <br />}-I ;i_s0 o,-/-;oou gallons 6 900 525 332 <br />7 1050 600 370 <br />i::u-w~ ,, 8 1200 675 408 <br />C. SOILS (refer to site evaluation) \ ',:S' I ;>_Q ) .;,_ \.\ <br />Number ---Depth to restricting layer = 11 Jf inches of ~-Cq,oc,lywu.11 <br />1. p :1 )I.-\ G-,.. <br />Bedrooms c.;,,c.y o-.i <br />2 Depth of percolation tests= I~)/ inches (pl1-l <s,ii-) <br />3. Percolation rate IS'.~ mpi 2cdcss 750 1,125 <br />3 cr4 1,000 1.500 <br />4. Land slope C % 5 cr6 1.500 2.250 <br />7 cr8 2.000 3,000 <br />cvc-9 See fig. C-6 (x 1.5) <br />D. ROCK LA YER DIMENSIONS <br />1. Multiply flow rate by 0.83 to obtain required area of rock <br />layer: A x 0.83 = ", <br />'7 :{O gpd x 0.83 sq. ft./ gpd = 1.,~~ sq. ft.--rJo ~-:.. l.,~l.\ <br />2 Select width of rock layer (10 feet or less) = /o ft. <br />3. Length of rock layer = area+ width = Rock Bed <br /><,, '6 Y sq. ft.+ ; o ft. = l--e ft. <br />E. ROCK VOLUME Length <br />1. Multiply rock area by rock depth to get cubic feet of rock; <br />~ sq. ft. x J,o~ ft. =~cu. ft. <br />2 Divide cu. ft. by 27 cu. ft./ cu. yd. to get cubic yards; <br />01 <c' cu. ft. + 27 =~cu. yd. <br />3. Multiply cubic yards by 1.4 to get weight of rock in tons; <br />;i "I cu. yd. x 1.4 ton/ cu. yd.= '3 ct tons. <br />F. ADSORPTION WIDIB L-'--A'-1 Lei:r-w1 Abson:>tion Width Sirin2 Table <br />1. Percolation rate in top 12 inches of soil is 1 ,£,s mpi <br />2. Select allowable soil loading rate from table; <br />,':I.$ gpd/ft2 <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+ , 4 ( gpd/ ft2 = :2, 1.:, ".2 <br />Pm:cl.tion Rate <br />Mi:1utes per in:h <br />(mpi) <br />Faster than 0.1 <br />0.1 to5 <br />0.1 to5 <br />6 to 1s <br />16 to 30 <br />31 to 45 <br />46 to 60 <br />61 tO 120 <br />Slower than 120 <br />Ca!lana <br />Soil Texture l"""'Y f'C'"!U ... 1 ... <br />~oarseSand 120 <br />Sand 1.20 <br />Fine Sand ... 0.60 <br />Sandy Loam 0.79 <br />Loam 0.60 <br />Silt Loam 0.50 <br />Clat:Loam 0.45 <br />lay 024 <br />Clav - <br />Type JV <br />60i, <br />o( <br />sic <br />\>llDCS <br />"' L-.c:. ·~ c,l-=rJ <br />l.,;ooi <br />rod<bod <br />Wldtnto <br />aboo.pcion <br />w,otl, <br />1.00 <br />1.00 <br />2.00 <br />1.52 <br />2.00 <br />2.40 <br />2.67 <br />5.00 - <br />" Soil h.iving ~ or more of fine or very fine sand. <br />4. Multiply adsorption width ratio by rock layer width to get <br />required adsorption width; <br />2JL2._ X .J.Q_ ft = ~ ft <br />I