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2. Within shorelands of public Waters, agricultural drain <br />tile may be used to intercept the seasonal high water table, <br />provided the groundwater table has a slope of at least two (2) feet <br />per one hundred (100) feet toward the public water, and provided <br />the drain tile are installed upslope of the soil treatment system. <br />There shall be at least twenty (20) feet of undisturbed soil <br />between the sidewall of the soil treatment unit and the <br />agricultural drain tile. <br />3. In all cases, the greatest practicable vertical separation <br />distance from the water table shall be provided. <br />Subd. 3 - Rapidly Permeable Soils <br />1. Filter material for a soil treatment unit using gravity <br />distribution of effluent shall not be placed in contact with <br />original soils having a percolation rate faster than one -tenth <br />(0.1) minute per inch. <br />2. For coarse soils having a percolation rate faster than <br />one -tenth (0.1) minute per inch, at least twelve (12) inches of <br />loamy sand textured soil having a percolation rate between six (6) <br />and fifteen (15) minutes per inch at the original site shall be <br />placed between the filter material and the coarse soil along the <br />excavation bottom and sidewalls. The size of the soil treatment <br />system must be based on the required treatment area for a soil <br />having a percolation rate of 16 to 30 minutes per inch as specified <br />in Table II. <br />3. For soils with percolation rates between one -tenth (0.1) <br />and five (5) minutes per itch, at least one of the following <br />treatment techniques shall be' used: <br />a. Distribute the sewage tank effluent by pressure flow over <br />the treatment area as specified in this chapter. <br />b. Divide the total soil treatment area into at least four <br />equal parts connected serially; or <br />c. Provide at least 12 inches of loamy sand textured soil <br />with a percolation rate between six and 15 minutes per <br />inch in situ between the drainfield rock and the coarse <br />soils. Trenches must be used with this liner system. <br />The size of the soil treatment system must be based on <br />the required treatment area for a soil having a <br />percolation rate between 16 to 30 minutes per inch as <br />specified in Table II. <br />