17.36.101 DEFINITIONS

For purposes of subchapters 1, 3, 6, and 8, the following definitions apply:

(1) "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.

(2) "Bedroom" means any room that is or may be used for sleeping. An unfinished basement is considered as an additional bedroom.

(3) "Campground" is defined in 50-52-101, MCA.

(4) "Certificate of survey" is defined in 76-3-103, MCA.

(5) "Cesspool" means a seepage pit without a septic tank to pretreat the wastewater.

(6) "Condominium" is defined in 70-23-101, MCA.

(7) "Connection" means a water or wastewater line that connects a single building or living unit to a shared, multiple user or public water or wastewater system.

(8) "Department" means the Montana Department of Environmental Quality.

(9) "Deviation" means a department-approved departure from a requirement contained in a department circular.

(10) "Drainageway" means a course or channel along which storm water moves in draining an area.

(11) "Dry well" means a storm water detention structure that collects surface runoff and discharges the water below the natural ground surface.

(12) "Dwelling" or "residence" means any structure, building, or portion thereof, which is intended or designed for human occupancy and supplied with water by a piped water system.

(13) "Escarpment" means any slope greater than 50% that extends vertically six feet or more as measured from toe to top.

(14) "Experimental system" means a wastewater treatment system for which specific design standards are not provided in Department Circular DEQ-4 or DEQ-2.

(15) "Floodplain" means the area adjoining the watercourse or drainway that would be covered by the floodwater of a flood of 100-year frequency except for sheetflood areas that receive less than one foot of water per occurrence and are considered zone b areas by the federal Emergency Management Agency. The floodplain consists of the floodway and the floodfringe, as defined in ARM 36.15.101.

(16) "Gray water" means wastewater that is collected separately from sewage flow and that does not contain industrial chemicals, hazardous wastes, or wastewater from toilets.

(17) "Ground water monitoring" means measuring the depth from the natural ground surface to the seasonally high ground water for a long enough period of time to detect a peak and then a sustained decline in the ground water level.

(18) "Holding tank" means a watertight receptacle that receives wastewater for retention and does not as part of its normal operation dispose of 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 17.36.319.

(19) "Impervious layer" means any layer of material in the soil profile that has a percolation rate slower than 120 minutes per inch.

(20) "Individual water system" means any water system that serves one living unit or commercial structure. The total number of people served may not exceed 24.

(21) "Individual wastewater system" means a wastewater system that serves one living unit or commercial structure. The total number of people served may not exceed 24.

(22) "Limiting layer" means bedrock, an impervious layer, or seasonally high ground water.

(23) "Living unit" means the area under one roof occupied by a family. For example, a duplex is considered two living units.

(24) "Local health officer" means health officer as defined in 50-2-101, MCA, or the health officer's designee.

(25) "Lot" is synonymous with "tract" or "parcel" for purposes of this chapter.

(26) "Mixing zone" is defined in 75-5-103, MCA.

(27) "Mobile home" means a trailer equipped with necessary service connections that is designed for use as a long-term residence.

(28) "Multiple user wastewater system" means a non-public wastewater system that serves or is intended to serve three through 14 living units or three through 14 commercial structures. The total number of people served may not exceed 24. In estimating the population served, the reviewing authority shall multiply the number of living units times the county average of persons per living unit based on the most recent census data.

(29) "Multiple user water supply system" means a non-public water supply system designed to provide water for human consumption to serve three through 14 living units or three through 14 commercial structures. The total number of people served may not exceed 24. In estimating the population served, the reviewing authority shall multiply the number of living units times the county average of persons per living unit based on the most recent census data.

(30) "Municipal" means pertaining to an incorporated city or town.

(31) "Natural soil" means soil that has developed through natural processes and to which no fill material has been added.

(32) "Parcel" means a part of land which is created by a division of land or a space in an area used for recreational camping vehicles or mobile homes.

(33) "Percolation test" means a standardized test used to assess the infiltration rate in soils.

(34) "Piped water system" means a plumbing system that conveys water into a structure from any source including, but not limited to, wells, cisterns, springs, or surface water.

(35) "Plat" is defined in 76-3-103, MCA.

(36) "Preliminary plat" is defined in 76-3-103, MCA.

(37) "Public wastewater system" means a system for collection, transportation, treatment, or disposal of wastewater that serves 15 or more families or 25 or more persons daily for a period of at least 60 days in a calendar year. In estimating the population served, the department shall multiply the number of living units times the county average of persons per living unit based on the most recent census data.

(38) "Public water supply system" means a system for the provision of water for human consumption from a community well, water hauler for cisterns, water bottling plant, water dispenser, or other water supply that has at least 15 service connections or that regularly serves at least 25 persons daily for any 60 or more days in a calendar year.

(39) "Recreational camping vehicle" means a vehicle that is used for non-permanent residence and is moved frequently.

(40) "Redoximorphic features" or "mottling" means soil properties associated with wetness that results from the reduction and oxidation of iron and manganese compounds in the soil after saturation and desaturation with water.

(41) "Reviewing authority" is defined in 76-4-102, MCA.

(42) "Sealed pit privy" means an enclosed receptacle designed to receive non-water-carried toilet wastes into a watertight vault.

(43) "Seasonally high ground water" means 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.

(44) "Seepage pit" means a covered underground receptacle that receives wastewater after primary treatment and allows the wastewater to seep into the surrounding soil.

(45) "Septic tank" means a storage 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.

(46) "Sewage" is synonymous with "wastewater" for purposes of this chapter.

(47) "Shared wastewater system" means a wastewater system that serves or is intended to serve two living units or commercial structures. The total number of people served may not exceed 24.

(48) "Shared water system" means a water system that serves or is intended to serve two living units or commercial structures. The total number of people served may not exceed 24. In estimating the population served, the reviewing authority shall multiply the number of living units times the county average of persons per living unit based on the most recent census data.

(49) "Site evaluation" means an evaluation to determine if a site is suitable for the installation of a subsurface wastewater treatment system.

(50) "Slope" means the rate that a ground surface declines in feet per 100 feet. It is expressed as percent of grade.

(51) "Soil consistence" means the attributes of soil material as expressed in degree of cohesion and adhesion or in resistance to deformation or rupture. See Appendix B of Department Circular DEQ-4.

(52) "Soil profile" means a description of the soil strata to a depth of eight feet using the USDA soil classification system.

(53) "Soil structure" means the combination or arrangement of primary soil particles into secondary units or peds. See Appendix B of Department Circular DEQ-4.

(54) "Soil texture" means the amount of sand, silt or clay measured separately in a soil mixture. See appendix B of Department Circular DEQ-4.

(55) "Spring" means natural opening in the earth's surface from which water issues or seeps.

(56) "Septic tank" means a storage settling tank in which settled sludge is in immediate contact with the sewage flowing through the tank while the organic solids are decomposed by anaerobic bacterial action.

(57) "State waters" is defined in 75-5-103, MCA.

(58) "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.

(59) "Surface water" means any water on the earth's surface including, but not limited to, streams, lakes, ponds, reservoirs, and irrigation ditches, whether fresh or saline.

(60) "Unstable land forms" means areas showing evidence of mass down-slope movement such as hummock hill slopes, debris flows, landslides, and rock falls. Unstable land forms may be evidenced by slip surfaces roughly parallel to the hillside; landslide scars and carving debris ridges; fences, trees, or telephone poles which appear tilted; or tree trunks which bend uniformly as they enter the ground.

(61) "Waiver" means a department-approved departure from a requirement contained in department rules. Granting of waivers must be in accordance with ARM 17.36.601.

(62) "Wastewater" means water-carried waste that is discharged from a dwelling, building, or other facility, including:

(a) household, commercial, or industrial wastes;

(b) chemicals;

(d) animal and vegetable matter in suspension or solution.

(63) "Wastewater treatment system" or "wastewater disposal system" means a system that receives wastewater for purposes of treatment, storage, or disposal. The term includes, but is not limited to, pit privies and experimental systems.

(64) "Well" means an artificial excavation that derives water from the interstices of rocks or soil which it penetrates.

(65) "Zone of saturation" means the area beneath the ground in which all open spaces are filled with ground water.

History: 76-4-104, MCA; IMP, 76-4-104, MCA; Eff. 12/31/72; AMD, Eff. 11/4/73; AMD, Eff. 11/3/75; AMD, Eff. 5/6/76; AMD, 1977 MAR p. 746, Eff. 10/25/77; AMD, 1984 MAR p. 1027, Eff. 7/13/84; AMD, 1984 MAR p. 1568, Eff. 10/26/84; AMD, 1992 MAR p. 2145, Eff. 9/25/92; TRANS, from DHES, 1996 MAR p. 1499; AMD, 2000 MAR p. 967, Eff. 4/14/00; AMD, 2000 MAR p. 3371, Eff. 12/8/00; AMD, 2002 MAR p. 1981, Eff. 5/17/02; AMD, 2003 MAR p. 221, Eff. 2/14/03; AMD, 2009 MAR p. 1786, Eff. 10/16/09.