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The total area selected for the mound, including that under the dikes, shall bc roughened in order <br /> to thoroughly break up any existing sod la}�ers and to provide a suitable transition zone betwecn <br /> thc original soil and sand layer of the mound. The area shall be roughened only whcn the <br /> moisture content of the soil 8 inches below the surface is dricr than thc plastic limit. <br /> Surface preparation or roughening may be performed with a mold board plow, a disk plow, or <br /> a back hoe using only the teeth. Mold board plow furrows shall be at least 8 inches deep, shall <br /> be thrown up slope and shall run perpendicular to the slope. There shall be no dcad furrow <br /> undcr the mound. <br /> Disking may be used for surface preparation as a substitutc for mold board plowing in soils <br /> having percolation rates faster than 15 minutes per inch (sand�� loam) in the top 8—inch depth. <br /> Back hoe teeth may be used to roughen the soil surface and brcak up thc sod laycr. Care must <br /> be taken so as not to compact or puddle deeper soil la}'crs: In »o case shall an}� surface soil be <br /> excavated and removcd from the arca. <br /> Mound Construction shall procecd immediately after surface preparation is complcted. Ever}� <br /> effort should be taken to pre��ent rain from fallinQ on the preparcd soil surface. <br /> CONSTRUCTION MATERIALS AND PROCEDURES; DISTRIBUTION OF EFFLUENT: <br /> A minimum of 12" of soil defincd as sand shall bc placcd whcrc thc filtcr matcrial is to bc <br /> located. A crawler tractor with a bladc or bucket shall be used to move the sand into place. At <br /> least 6 inches of sand shall be kept under the trachs to minimizc compacting of the plowed layer. <br /> The sand la}'er upon which the filter material is placcd shall bc le�el. ��r,, <br /> � <br /> Sand is defined as a soil te�ture composed b�� wcight of a least <br /> 25 percent of very coarse, and mcdium sand var��ing in size from ?.0 to 0.?� mm, Icss tha��0 <br /> percent of fine or very fine sand ranging in size between 0.?> and 0.0� mm, and no morc that <br /> 10 perccnt of particics smallcr that 0.0> mm. <br /> A minimum depth of 9 inches of filter material (rock) shall bc placed on thc sand layer prior to <br /> installing the distribution pipc. <br /> Filter material is defined as clean rock, crushcd igneous rock or similar insoluble, durable a�ld <br /> deca}�—resistant material free from dust, sand, silt or clay. The size shall rangc from 3/4 inch <br /> diametcr to 2 1/2 inch diameter. <br /> PAGE 3 <br />