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54 I I I I I I I I I I I I I I I I I I I 4. Where the percolation rate of the original soil is slower than 60 minutes per inch, at least 12 inches of fill material having a texture defined as sand must be placed between the drainfield rock and the original soil along the excavation bottom. 5. Construction equipment wheels or tracks must not be placed in contact with the bottom of the excavation during the construction of a soil treatment system in soils having a percolation rate slowerthan 15 minutes per inch. 6. The size of the soil treatment system must be based on an acceptance rate of 0.24 gallons per square foot, which is equivalent to a sizing factor of 4.2 square feet per gallons per day. 150.014G. FINAL TREATMENT AND DISPOSAL. ALTERNATIVE SYSTEMS SUBDIVISION 1. GENERAL. The contents of this section apply to the final treatment and disposal of the effluent of a system constructed in accordance with Section 150.01.4. The intent of this section is to provide sewage treatment solutions for those site or soil conditions where a standard system cannot be installed or is not the most suitable type of sewage treatment system. SUBDIVISION 2. FLUCTUATING GROUNDWATER. 1. Where natural drainage will not provide four (4) feet of separation between the bottom of the soil treatment area and the highest known or calculated level of the water table, agricultural drain tile may be used to intercept or lower the seasonal high water table, except with shorelands of public waters. There shall be at least ten (10) feet of undisturbed soil between the sidewall of the soil treatment unit and the agricultural drain tile. 2. Within shorelands of public waters, agricultural drain tile may be used to intercept the seasonal high water table, provided the groundwater table has a slope of at least two (2) feet per one hundred (100) feet toward the public water, and provided the drain tile are installed upslope of the soil treatment system. There shall be at least twenty (20) feet of undisturbed soil between the sidewall of the soil treatment unit and the agricultural drain tile. 3. In all cases, the greatest practicable vertical separation distance from the water table shall be provided. SUBDIVISION 3. RAPIDLY PERMEABLE SOILS. 1. Filter material for a soil treatment unit using gravity distribution of effluent shall not be placed in contact with original soils having a percolation rate faster than one- tenth (0.1) minute per inch. 2. For coarse soils having a percolation rate faster than one-tenth (0.1) minute per inch, at least twelve (12) inches of loamy sand textured soil having a percolation rate between six (6) and fifteen (15) minutes per inch at the original site shall be placed between the filter material and the coarse soil along the excavation bottom and sidewalls. The size of the soil treatment system must be based on the required treatment area for a soil having a percolation rate of 16 to 30 minutes per inch as specified in Table II.