Administrative Rules of Montana › Department 17 - ENVIRONMENTAL QUALITY › Chapter 17.36 - SUBDIVISIONS/ON-SITE SUBSURFACE WASTEWATER TREATMENT › Subchapter 17.36.9 - On-Site Subsurface Wastewater Treatment Systems › Rule 17.36.912 - DEFINITIONS

Current through Register Vol. 13, July 5, 2024
For purposes of this subchapter, the following definitions
				  apply:
(1) "Absorption bed" means an
				absorption system that consists of excavations greater than three feet in width
				where the distribution system is laid for the purpose of distributing
				pretreated waste effluent into the ground.
(2) "Absorption trench" means an absorption
				system that consists of excavations less than or equal to three feet in width
				where the distribution system is laid for the purpose of distributing
				pretreated waste effluent into the ground.
(3) "Bedrock" means material that cannot be
				readily excavated by hand tools, or material that does not allow water to pass
				through or that has insufficient quantities of fines to provide for the
				adequate treatment and disposal of wastewater. The term does not include gravel
				and other rock fragments as defined in Department Circular DEQ-4, Appendix
				B.
(4) "Cesspool" means a seepage
				pit without a septic tank to pretreat the wastewater.
(5) "Commercial unit" means the area under
				one roof that is occupied by a business or other nonresidential use. A building
				housing two businesses is considered two commercial units.
(6) "Department" means the Montana Department
				of Environmental Quality.
(7)
				"Drainage way" means a course or channel along which storm water moves in
				draining an area.
(8) "Experimental
				system" means a wastewater treatment system for which specific design standards
				are not provided in Department Circular DEQ-4, DEQ-2, or this
				subchapter.
(9) "Failed system"
				means a wastewater treatment and/or disposal system that no longer provides the
				treatment and/or disposal for which it was intended, or violates any of the
				requirements of ARM
				17.36.914.
(10) "Floodplain" means the area adjoining
				the watercourse or drainway that would be covered by a flood that is expected
				to recur on the average of once every 100 years or by a flood that has a one
				percent chance of occurring in any given year. The floodplain consists of the
				floodway and the flood fringe, as defined in ARM Title 36, chapter
				15.
(11) "Gray water" means
				wastewater that is collected separately from a sewage flow and that does not
				contain industrial chemicals, hazardous wastes, or wastewater from
				toilets.
(12) "Ground water
				observation well" means a well installed for the purpose of measuring the depth
				from the natural ground surface to the seasonally high ground water.
(13) "Holding tank" means a watertight
				receptacle that receives wastewater for retention and does not, as part of its
				normal operation, dispose or treat the wastewater. The term does not include
				surge tanks used in a gray water irrigation system if the system meets the
				requirements of ARM
				17.36.919.
(14) "Impervious layer" means any layer of
				material in the soil profile that has a percolation rate slower than 240
				minutes per inch.
(15) "Individual
				wastewater system" means a wastewater system that serves one living unit or
				commercial unit. The term does not include a public sewage system as defined in
				75-6-102, MCA.
(16) "Limiting layer" means bedrock, an
				impervious layer, or seasonally high ground water.
(17) "Living unit" means the area under one
				roof that can be used for one residential unit and which has facilities for
				sleeping, cooking, and sanitation. For example, a duplex is considered two
				living units.
(18) "Multiple-user
				wastewater system" means a wastewater system that serves or is intended to
				serve more than two living units or commercial units or a combination, but
				which is not a public sewage system as defined in
				75-6-102, MCA. In estimating the
				population that will be served by a proposed residential system, the reviewing
				authority shall multiply the number of living units by 2.5.
(19) "Municipal" means pertaining to an
				incorporated city or town.
(20)
				"Percolation test" means a standardized test used to assess the infiltration
				rate of soils, performed in accordance with Appendix A in Department Circular
				DEQ-4.
(21) "Piped water supply"
				means a plumbing system that conveys water into a structure from any source
				including, but not limited to, wells, cisterns, springs, or surface
				water.
(22) "Pit privy" means a pit
				that receives undiluted, non-water-carried toilet wastes.
(23) "Replacement system" means a wastewater
				treatment system proposed to replace a failed, failing, or contaminating
				system.
(24) "Reviewing authority"
				means a local board of health or local health officer, as those terms are
				defined in
				50-2-101, MCA, or their
				designees.
(25) "Sealed pit privy"
				means an enclosed receptacle designed to receive non-water-carried toilet
				wastes into a watertight vault.
(26) "Seasonally high ground water" means the
				depth from the natural ground surface to the upper surface of the zone of
				saturation, as measured in an unlined hole or perforated monitoring well during
				the time of the year when the water table is the highest. The term includes the
				upper surface of a perched water table.
(27) "Seepage pit" means a covered
				underground receptacle that receives wastewater after primary treatment and
				allows the wastewater to seep into the surrounding soil.
(28) "Septic tank" means a wastewater
				settling tank in which settled sludge is in immediate contact with the
				wastewater flowing through the tank while the organic solids are decomposed by
				anaerobic action.
(29) "Shared
				wastewater system" means a wastewater system that serves or is intended to
				serve two living units or commercial units or a combination of both. The term
				does not include a public sewage system as defined in
				75-6-102, MCA.
(30) "Site evaluation" means an evaluation to
				determine if a site is suitable for the installation of a subsurface wastewater
				treatment system.
(31) "Slope"
				means the rate that a ground surface declines in feet per 100 feet. It is
				expressed as percent of grade.
(32)
				"Soil profile" means a description of the soil strata to a depth of eight feet
				using the United States Department of Agriculture (USDA) soil classification
				system method in Appendix B, Department Circular DEQ-4.
(33) "Subsurface wastewater treatment system"
				means the process of wastewater treatment in which the effluent is applied
				below the soil surface or into a mound by an approved distribution
				system.
(34) "Variance" means the
				grant, pursuant to ARM
				17.36.922, by the reviewing
				authority of an exception to the minimum requirements set out in this
				subchapter or Department Circular DEQ-4.
(35) "Wastewater" means water-carried wastes.
				For purposes of these rules, wastewater does not include storm water. The term
				includes, but is not limited to, the following:
(a) household, commercial, or industrial
				wastes;
(b) chemicals;
(c) human excreta; or
(d) animal and vegetable matter in suspension
				or solution.