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- 23 - <br /> <br />surrounding ground water supplies. The pit excavation shall terminate at least <br />four (4) feet above the highest known or calculated ground water table. <br /> <br />When two (2) or more seepage pits are used, a distribution box constructed in <br />accordance with Section 150.01.4D shall be used if the inlet inverts of the <br />seepage pits have no more than one (1) foot difference in elevation. If the <br />difference in elevation between the inlet inverts is greater than one (1) foot, <br />the seepage pits shall be connected in series. <br /> <br />The location of seepage pits, in addition to the general provisions under <br />Section 150.01.4F, shall be not less than the stated minimum distances from the <br />fo 1 lowing: <br /> <br />Wells less than fifty (50) feet in depth and not encountering at least <br />ten (10) feet of impervious material ........ 150 ft. <br />Any water supply well or buried water's~c~i~n pipe ....... 75 ft. <br />Buildings ........................... 20 ft. <br />Property lines and buried pipe distribution water under <br />pressure ............................ 10 ft. <br />Other seepage pits .......... --- - - --_ 3 times <br /> the diameter of the largest ~i~ ie~gg to'edge). <br /> <br />Effective soil treatment area of a seepage pit shall be calculated as the <br />sidewall area below the inlet, exclusive of any hardpan, rock, or clay <br />formations. The sidewall area shall be based on the outer diameter of the pit <br />lining plus twelve (12) inches of rock in the annular space. <br /> <br />Required treatment area shall be determined by the percolation test described in <br />Section 150.01.4A and from using the col~n for seepage beds in Table II. In <br />no case shall a seepage pit be installed in soils where the percolation rate of <br />any stratum is faster than one-half (1/2) minute per inch (coarse sand). A <br />percolation test shall be made in each vertical stratum penetrated by the <br />seepage pit, and the weighted average of the results, exclusive of results from <br />soil strata in which the percolation rate is slower than thirty (30) minutes per <br />inch, shall be computed and applied to the seepage bed column of Table II as <br />indicated. <br /> <br /> 1. A minimum of four (4) feet composite depth of porous formation for <br />each installation shall be provided in one (1) or more pits. <br /> <br />2. Ail pits shall have an inside diameter of at least five (5) feet. <br /> <br />Construction of all seepage pits shall conform to the following requirements: <br /> <br /> 1. To prevent cave-in, the pit shall be precast concrete or lined with <br />brick, stone or block at least four (4) inches thick, laid in a radial ard] to <br />support the pit walls. <br /> <br /> 2. The brick, stone, or block shall be laid watertight above the inlet <br />and with open joints l~low the inlet to provide adequate passage of liquids. <br /> <br /> 3. A minimum annular space of twelve (12) inches between the pit <br />lining and excavation wall shall be filled with crushed rock or gravel. <br /> <br /> <br />