Agenda - Council - 05/13/2014 - Laserfiche WebLink

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39 INDIVIDUAL SUBSURFACE SEWAGE TREATMENT SYSTEMS 7080.2050 in the pipe exceed 15 feet per second. For pressure systems, a minimum slope of one percent for drainback or other frost protection measures must be employed. D. Access to each supply pipe must be provided for cleanout. The access point must be accessible from final grade. Subp. 3. Gravity distribution. A. Serial distribution must be used to distribute effluent to individual trenches in a soil treatment and dispersal system. If the necessary elevation differences between trenches for serial distribution cannot be achieved by natural topography or by varying the excavation depths, parallel distribution must be used. Serial distribution must not create a pressure head on trenches at lower elevations. B. If drop boxes are used for serial distribution, subitems (1) to (6) apply. (1) The drop box must be watertight and constructed of durable materials not subject to corrosion or decay. (2) The invert of the inlet supply pipe must be at least one inch higher than the invert of the outlet supply pipe to the next drop box. (3) The invert of the outlet supply pipe to the next drop box must be no greater than two inches higher than the crown of the distribution pipe serving the trench in which the box is located. (4) When sewage tank effluent is delivered to the drop box by a pump, the pump discharge must be directed against a wall or side of the box on which there is no outlet or directed against a deflection wall, baffle, or other energy dissipater. The discharge rate into the drop box must not result in surfacing of sewage from the drop box. The supply pipe must drain after the pump shuts off. (5) The drop box must be covered by a minimum of six inches of soil. If the top of the box is deeper than six inches, access must be provided above, at, or within six inches of finished grade. (6) The drop box must be placed on firm and settled soil. C. If valve boxes are used, all requirements of item B apply to valve boxes. D. Distribution boxes must meet the standards in subitems (1) to (6). (1) The box must be watertight and constructed of durable materials not subject to corrosion or decay. (2) The distribution box must be covered by a minimum of six inches of soil. If the top of the box is deeper than six inches, access must be provided above, at, or within six inches of the finished grade. (3) The inverts of all outlets must be set and maintained at the same elevation. (4) The inlet invert must be either at least one inch above the outlet invert or sloped such that an equivalent elevation above the outlet invert is obtained within the last eight feet of the inlet pipe. (5) Each trench line must be connected separately to the distribution box and must not be subdivided. Distribution boxes must not be connected to one another if each box has distribution pipes. (6) When sewage tank effluent is delivered by pump, a baffle wall must be installed in the distribution box or the pump discharge must be directed against a wall, baffle, side of the box on which there is no outlet, or directed against a deflection wall, baffle, or other energy dissipater. The baffle must be secured to the box and extend at least one inch above the crown of the inlet pipe. The discharge rate into Copyright ©2014 by the Rev so of Statutes, State of Minnesota. All Rights Reserved.