NAC444.835. Soil absorption system: General requirements.

     1. The effluent from a septic tank or other primary treatment unit must be disposed of through a soil absorption trench or through an absorption system approved by the administrative authority.

     2. The size and type of the absorption area required for the disposal of the effluent must be determined according to the results of the percolation testing and the requirements for the sizing of the appropriate septic tank, except that if the percolation testing yields a percolation rate of less than 10 minutes per inch, the percolation rate shall be deemed to be 10 minutes per inch.

     3. Soils to be used in a soil absorption trench must have a percolation rate that is 120 minutes per inch or less without interference from groundwater or impervious strata below the level of the absorption system. A test pit must be excavated and the profile of the soil to a minimum depth of 5 feet below the bottom of the proposed absorption system must be recorded in a log for the profile of the soil. Impervious barriers, bedrock, fractures, areas of open solution, clay, caliche or other limiting factors which may affect the effluent disposal area must be indicated in the log.

     4. A soil absorption system intended for use on soils with percolation rates greater than 60 minutes per inch, or intended for commercial use, must be designed by an engineer.

     5. The depth to the seasonal high groundwater, as observed as the surface of free water or as indicated by mottling or historical documentation, must be indicated in the log for the profile of the soil.

     6. Unless otherwise approved by the administrative authority, the owner of the absorption system shall maintain at least 4 feet between the bottom of the disposal trench or absorption area and the level of seasonal high groundwater, impervious barriers or other limiting soil characteristics.

     7. If the absorption trench will be placed in any soil which has a percolation rate of less than 2 minutes per inch, the administrative authority may, depending on the characteristics of the soil and site, require that:

     (a) The trench be specially designed by an engineer; and

     (b) The required setbacks from any well or watercourses be increased.

     8. Effluent from a tank for the treatment of wastewater must be disposed of through a solid watertight pipe that is at least 5 feet in length and placed immediately before the absorption system.

     9. The tank for the treatment of wastewater and the soil absorption system must be separated by at least 5 feet, and the solid watertight pipe that connects the tank and the absorption system must be placed on undisturbed soil.

     10. Distribution lines must be of equivalent length unless otherwise authorized by the administrative authority.

     11. The slowest percolation rate generated by the percolation tests must be used to determine the required size of an absorption system.

     12. An individual sewage disposal system must be designed to include a reserve absorption area which is equal in size to at least 100 percent of the primary required absorption area. The reserve absorption area must not be paved and is subject to the setback requirements for the primary absorption area. No vehicles may travel on the reserve absorption area.

     (Added to NAC by Bd. of Health by R129-98, eff. 3-25-99)