Administrative Rules of Montana › Department 17 - ENVIRONMENTAL QUALITY › Chapter 17.36 - SUBDIVISIONS/ON-SITE SUBSURFACE WASTEWATER TREATMENT › Subchapter 17.36.3 - Subdivision Requirements › Rule 17.36.319 - GRAY WATER REUSE

Current through Register Vol. 13, July 5, 2024
(1) This rule
				applies to gray water reuse on subdivision parcels that are subject to review,
				or that have been approved, under Title 76, chapter 4, MCA.
(2) Except as provided in (3) and (4),
				treatment and disposal of gray water must be by means of a wastewater treatment
				system that meets all of the requirements of this chapter and applicable
				department circulars. Gray water reuse within a building or residence for uses
				such as toilet flushing is permitted without review, provided that the gray
				water is ultimately disposed of by means of a wastewater treatment system that
				is in compliance with this chapter and applicable department
				circulars.
(3) Gray water may be
				used for irrigation as provided in (4). If a gray water irrigation system meets
				all of the requirements in (4), the system is not subject to the requirements
				of subchapter 3.
(4) Gray water
				that is collected separately from sewage flow and that does not contain
				industrial chemicals, hazardous wastes, or wastewater from toilets may be used
				for irrigation, if the following requirements are met:
(a) prior to installation, a gray water
				irrigation system must have a permit from the local health
				department;
(b) gray water
				irrigation must be subsurface, with a collection and application system that is
				designed, installed, and used in accordance with Department Circular
				DEQ-4;
(c) as provided in
				75-5-326, MCA, gray water may not
				be used to irrigate plants to be consumed by humans, and gray water systems may
				not be located within a floodplain, as defined in
				76-5-103, MCA. For purposes of
				this rule, "plants to be consumed by humans" does not include nut and fruit
				trees;
(d) there must be a minimum
				of four feet of natural soil between the point of gray water application and a
				limiting layer, as defined in ARM
				17.36.101;
(e) unless a waiver is granted by the
				department, the following horizontal setback distances must be maintained. Gray
				water irrigation may not occur within:
(i)
				100 feet of wells;
(ii) 100 feet of
				surface water;
(iii) 100 feet of a
				floodplain; or
(iv) two feet of a
				property line;
(f) gray
				water from kitchens may be used for irrigation only where a waste segregation
				system is used. For purposes of this rule, a "waste segregation system"
				consists of dry disposal of toilet waste by a method such as composting,
				chemical, dehydrating, or incinerator treatment, with a separate disposal
				method for gray water;
(g) gray
				water irrigation systems in subdivisions may not be installed unless approved
				under Title 76, chapter 4, MCA. If a system complies with (4)(a) through (e),
				review under Title 76, chapter 4, MCA, is not required if the system serves:
(i) a parcel that has a previous certificate
				of subdivision approval issued pursuant to Title 76, chapter 4, MCA, if no
				other changes to the certificate are proposed, except that review under Title
				75, chapter 6, MCA, is required before a public wastewater system is modified
				to include a gray water irrigation system; or
(ii) a parcel that, when created, was exempt
				from review under Title 76, chapter 4, MCA, because it was served solely by
				municipal facilities, as defined in
				76-4-102, MCA.