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Mr. John Laurent - 2 - April 14, 1981 <br />Soil Texture at Percolation Rate <br />Hole Elevation Depth(inches) Bottom of Hole (min/in) <br />#1 99.3 28 Clay loam 0.4 <br />#2 98.1 26 Sandy clay loam 5.0 <br />#3 99.6 27 Silty clay loam 3.5 <br />#4 98.2 22 Sandy clay loam 4.7 <br />#5 97.7 24 Sandy clay loam 6.9 <br />#6 97.5 26 Sandy clay loam 3.9 <br />i #7 99.8 28 Sandy clay loam 5.7 <br />#8 101.0 28 Sandy clay loam to 0.9 <br />sandy loam <br />#9 99.0 32 Sandy loam 6.2 <br />#10 100.5 24 Sandy clay loam 5.0 <br />#11 98.7 26 Sandy clay loam 5.7 <br />#12 97.2 26 Sandy clay loam to 6.4 <br />clay loam <br />The measured percolation rates are somewhat rapid for the texture of the soil <br />materials in which the percolation tests were run. <br />"1 The two mound systems are designed to serve four bedroom houses. The deoigns <br />:j are essentially the same. The size of the rock bed is based on an estimated <br />daily sewage flow of 600 gallons per day. The design infiltration rate of the <br />j medium sand fill of the mound is 1.2 gallons per square foot per day. Therefore, <br />the required rock bed area is 500 square feet. <br />600 gal/day s 1.2 gal/ft2/day - 500 ft2 <br />A rock bed 10 feet wide by 50 feet long provides the needed area. With 1.5 <br />feet of medium nand below the rock bed and 3:1 sideslopes on the finish cover, <br />the mound skirt covers an area 31 feet wide by 71 feet long. <br />Because: the mound systems will be constructed on slopes, a calculation of the <br />basal area (effective absorption -rea) under the mound is needed. The effective <br />basal area of each mound equals the downslope width multiplied by the bed length <br />(20.5 feet times 50 feet equals 1025 square feet). The required basal area is <br />determined by dividing the loading rate (600 gallons per day) by th- infiltrative <br />capacity of the natural soil (0.74 gallons T)er day for a soil with a percolation <br />late of between 30-60 minutes per inch, silty clay loam to clay loam soits). <br />600 gal/day r 0.74 gal/ft2/day r 811 ft2 <br />This calculation shows that sufficient effective basal area is provided by the <br />design. <br />The pressure distribution system of the mound consists of Schedule 40 PVC plastic <br />pipe. The supply line and manifold pipe are 2.0 inch inside diameter pipe. The <br />t <br />