Agenda - Council - 08/08/1989 - Closed Executive Session and Regular Meeting

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5. Soil treatment areas shall not be placed in flood plains delineated Dy local ordinances adopted in compliance with the Statewide Standards and Criteria for Management of Flood Plain Areas of Minnesota (Chapter C!20), or in areas for wkich regional flood information is available from the Deiartment of Resources except that in areas where ten year flood information is available from and/or approved by the DNR, soil treatment systems may be installed in accordance with the provisions of Chapter 7080.0210. 6. Soil treatment areas of individual sewage treatment systems that are designed to treat an estimated daily sewage flow greater than 3,000 gallons per day must be separated from other similarly sized systems by at least 300 feet. Design and Construction 1. The bottom of trenches and beds shall be at least four (4) feet above the water table or bedrock. 2. The trenches shall be not less than eighteen (18) inches, nor more than thirty-six (36) inches wide. Any trench wider than thirty-six (36) inches shall be considered a bed. No bed may be wider than 25 feet and parallel beds must not be located closer than ten feet apart. 3. Trenches and beds shall be not more than one hundred (100) feet in length. 4. The bottom of the trench of bed excavation shall be level. 5. The bottom and sides of the soil treatment system to the top of the drainfield rock shall be excavated in such a manner as to leave the soil in a natural, unsmeared, and uncompacted condition. Excavation shall be made only when the soil moisture content is at or less than the plastic limit. 6. When the soil percolation rate at the bottom of the trench or bed is slower than fifteen (15) minutes per inch, no vehicle or excavation equipment shall be allowed on the trench or bed area. Excavation shall be by back hoe or other means that allow the equipment wheels or tracks to remain on the surface soils. Excavation equipment or other vehicles shall not be driven on the soil treatment area. 7. There shall be a layer of at least six (6) inches, but no more than twenty-four (24) inches of drainfield rock in the bottom of the trenches and beds. '8. Where disposal trenches are constructed within ten (10) feet of trees six (6) inches or larger in diameter, or dense shrubbery, or where it can reasonably be anticipated that such vegetation will be present during the expected life of the system, at least twelve (12) inches of filter material shall be placed beneath the distribution pipe.