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Seepage pits may be used for disposal of sewage effluent in the <br />Urban Service Area when such use is indicated by favorable <br />conditions of soil, ground water level, or topography, and where <br />such use does not reduce the safety of surrounding ground water <br />supplies. The pit excavation shall terminate at least four (4) <br />feet above the highest known or calculated ground water table. <br />When two (2) or more seepage pits are used, a distribution box <br />constructed in accordance with Section 150.01.4D shall be used if <br />the inlet inverts of the seepage pits have no more than one (1) <br />foot difference in elevation. If the difference in elevation <br />between the inlet inverts is greater than one (1) foot, the <br />seepage pits shall be connected in series. <br />The location of seepage pits, in addition to the general <br />provisions under Section 150.01.4F, shall be not less than the <br />stated minimum distances from the following: <br />Welts less than fifty (50) feet in depth and not <br />encountering at least ten (10) feet of impervious <br />material 150 ft. <br />Any water supply well or buried water suction <br />pipe 75 ft. <br />Buildings 20 ft. <br />Property lines and buried pipe distribution water <br />under pressure 10 ft. <br />Other seepage pits 3 times <br />the diameter of the largest pit (edge to edge) <br />Effective soil treatment area of a seepage pit shall be <br />calculated as the sidewall area below the inlet, exclusive of any <br />hardpan, rock, or clay formations. The sidewall area shall be <br />based on the outer diameter of the pit lining plus twelve (12) <br />inches of rock in the annular space. <br />Required treatment area shall be determined by the percolation <br />test described in Section 150.01.4A and from using the column for <br />seepage beds in Table II. In no case shall a seepage pit be <br />installed in soils where the percolation rate of any stratum is <br />faster than one —half (1/2) minuter per inch (coarse sand). A <br />percolation test shall be made in each vertical stratum <br />penetrated by the seepage pit, and the weighted average of the <br />results, exclusive of results from soil strata in which the <br />percolation rate is slower than thirty (30) minutes per inch, <br />shall be computed and applied to the seepage bed column of Table <br />II as indicated. <br />1. A minimum of four (4) feet composite depth of porous <br />formation for each installation shall be provided in one (1) or <br />more pits. <br />TI <br />