(1) The reviewing authority may require that percolation tests, conducted in accordance with department Circular DEQ-4, be performed within the boundary of each proposed subsurface sewage treatment system. Percolation tests must be keyed by a number on the lot layout to the results in the report form.
(2) If the applicant or the department has reason to believe that ground water will be within seven feet of the surface at any time of the year within the boundaries of the treatment system, ground water monitoring must be conducted in accordance with Department Circular DEQ-4.
(3) The applicant shall provide descriptions of the soils within 25 feet of the boundaries of each proposed drainfield. Soil descriptions for the proposed subdivision must meet the following requirements:
(a) Soil descriptions must be done in accordance with Department Circular DEQ-4. The characteristics that must be addressed include, but are not limited to, soil texture, soil structure, soil consistence, and indicators of redoximorphic features.
(b) Soil descriptions must be based on data obtained from test holes. Test holes must be dug in accordance with Department Circular DEQ-4. The number of test holes must be as provided in (c), unless a waiver is granted by the department pursuant to ARM 17.36.601. Before a waiver is granted, the applicant shall complete test holes for 25 percent of the proposed drainfield locations in the proposed subdivision, shall demonstrate that the soils are consistent throughout the area requested for a waiver, and shall obtain the approval of the local reviewing authority. The department may require additional test holes than are required in (c) if the department determines that there is significant variability of the soils in the proposed drainfield areas. Each test hole must be keyed by a number on a copy of the lot layout or map with the information provided in the application.
(c) At least one test hole must be dug for each individual drainfield and for each shared (two-user) drainfield. At least three test holes must be dug for each multiple-user and public drainfield. At least one test hole must be dug for each zone of a pressure-dosed drainfield.
(d) If the applicant or the department has reason to believe that a limiting layer is within seven feet of the ground surface at the site of a proposed subsurface sewage treatment system, the department may require additional test holes and soil descriptions sufficient to describe the suitability of the soil.
(4) Sewage systems that are subject to the design requirements of Department Circular DEQ-2 must meet the siting requirements of that circular.