R317-5-6. Design Requirements

  6.1. Shall meet the requirements of Section R317-4-6, with these exceptions:

  A. When a LUWD serves multiple single family dwellings the wastewater flow shall be estimated at 400 gpd per dwelling.

  B. Minimum separation distance from the bottom of the absorption trenches to the anticipated maximum ground water table is 48 inches. If a mound, sand lined trench, or packed bed pretreatment unit is designed and installed on the LUWD system, the horizontal separation distance may be reduced to 24 inches.

  6.2. Components Required in a LUWD System:

  A. A septic tank;

  B. An effluent filter;

  C. A pressurized subsurface disposal system.

  1. This may be an absorption field, deep wall trenches, absorption beds, or, for packed bed media applications, drip irrigation dispersal, depending on location, topography, soil conditions and maximum ground water level.

  2. Pressurized systems require cleanouts at the end of pressurized laterals and typically require a dosing chamber or dosing tank.

  3. The Utah Guidance for Performance, Application, Design, Operation and Maintenance: Pressure Distribution Systems document shall be used for design requirements, along with the following:

  a. Dosing pumps, controls and alarms shall comply with Section R317-4-14 Appendix B.

  b. Pressure distribution piping.

  i. All pressure transport, manifold, lateral piping, and fittings shall meet PVC Schedule 40 standards or equivalent.

  ii. The ends of lateral piping shall be constructed with sweep elbows or an equivalent method to bring the end of the pipe to the final grade. The ends of the pipe shall be provided with threaded plugs, caps, or other devices acceptable to the division to allow for access and flushing of the lateral.

  D. Accessibility components to insure proper maintenance and servicing. These include that all tanks shall have access risers to the surface of the ground; and absorption field inspection ports.

  E. Additional components may also be required depending on the waste stream characteristics and the need to provide adequate protection to groundwater. These components may include pretreatment devices such as grease traps, or may involve secondary treatment using packed bed media systems.