Administrative Rules of Montana › Department 17 - ENVIRONMENTAL QUALITY › Chapter 17.36 - SUBDIVISIONS/ON-SITE SUBSURFACE WASTEWATER TREATMENT › Subchapter 17.36.3 - Subdivision Requirements › Rule 17.36.323 - SETBACKS

Current through Register Vol. 13, July 5, 2024
(1) Minimum setback distances, in feet, shown
				in Table 2 of this rule must be maintained, except as provided in the table
				footnotes or as allowed through a deviation granted under ARM Title 17, chapter
				38, subchapter 1. The setbacks in this rule are not applicable to gray water
				irrigation systems that meet the setbacks and other requirements of ARM
				17.36.319.
TABLE 2
SETBACK DISTANCES
(in feet)
From
To
Drinking Water Wells
To
Sealed Components (1) and Other Components (2)
To
Drainfields/Soil Absorption Systems (3)
Public or multiple-user drinking water
							 wells/springs
-
100 (4)
100
Individual and shared drinking water wells
-
50 (18)
100 (18)
Other wells (5)
-
50 (4)
100 (4)
Suction lines
-
50
100
Cisterns
-
25
50
Roadcuts, escarpment
-
10 (6)
25
Slopes > 35 percent (7)
-
10 (6)
25
Property boundaries
10 (8)
10 (8)
10 (8)
Subsurface drains
-
10
10
Water mains
-
10 (9)
10
Drainfields/Soil absorption systems
100
10
-
Foundation walls
-
10
10
Surface water (10), springs
100 (4) (11) (12)
50 (4) (11)
100 (4) (11) (13)
Floodplains
10 (4) (11)
- Sealed components
- no setbacks (1)
Other components - 100 (2) (4) (11)
100 (11) (14)
Mixing zones
100 (4) (18)
-
-
Storm water ponds and ditches (15)
25 (4) (16)
10 (4)
25 (4)
Sewage Lagoons
1000 (17)
-
-
(1) Sealed
				components include holding tanks, sealed pit privies, raw wastewater pumping
				stations, the components addressed in chapters 4 and 5 of Department Circular
				DEQ-4, and those components completely contained within a sealed vessel. Sealed
				components must meet the requirements of ARM
				17.36.322(4).
				Drainfields do not have to meet setbacks to effluent transport pipes,
				manifolds, drop boxes, and distribution pipes as described in section 4.3 of
				DEQ-4.
(2) Other components include
				the components addressed in Department Circular DEQ-4, Chapter 7, except those
				components completely contained within a sealed vessel.
(3) Absorption systems include the systems
				addressed in Department Circular DEQ-4, Chapters 6 and 8, subject to the
				limitations in ARM
				17.36.321.
(4) A waiver of this requirement may be
				granted by the department pursuant to ARM
				17.36.601.
(5) Other wells include, but are not limited
				to, irrigation and stock watering, but do not include observation wells as
				addressed in Department Circular DEQ-4.
(6) Sewer lines and sewer mains may be
				located in roadways and on steep slopes if the lines and mains are safeguarded
				against damage.
(7) Down-gradient
				of the sealed component, other component, or drainfield/soil absorption
				system.
(8) Easements may be used
				to satisfy the setback to property boundaries.
(9) Unless a waiver is granted by the
				department pursuant to ARM 17.36.601, sewer mains that cross water mains must
				be laid with a minimum vertical separation distance of 18 inches between the
				mains.
(10) For purposes of this
				rule, "surface water" does not include intermittent storm water.
(11) The department may require more
				separation from the floodplain or from surface water or springs if it
				determines that site conditions or water quality requirements indicate a need
				for the greater distance.
(12)
				Pursuant to Department Circular DEQ-20, the reviewing authority may require
				greater than a 100-foot horizontal separation between a well and surface water
				if there is a potential that the well may be influenced by contaminants in the
				surface water.
(13) A waiver may be
				granted by the department. In addition to the requirements of ARM 17.36.601, a
				waiver request from this setback must demonstrate that ground water flow at the
				drainfield site cannot flow into the surface water or spring. The setback
				between drainfields or soil absorption systems to irrigation ditches does not
				apply if the ditch is lined with a full culvert.
(14) After consultation with the local health
				department, a waiver may be granted by the department, pursuant to ARM
				17.36.601. In addition to the requirements of ARM 17.36.601, a waiver request
				from this setback must:
(a) demonstrate that
				the surface water or spring seasonally high water level is at least 100-foot
				horizontal distance from the drainfield;
(b) demonstrate that the bottom of the
				drainfield will be at least two feet above the maximum 100-year flood
				elevation; and
(c) provide any
				required approval(s) from the local floodplain coordinator.
(15) Storm water ponds and ditches
				are those structures that temporarily hold or convey water as part of storm
				water management.
(16) The setback
				is 100 feet for public wells, unless a deviation is granted under ARM Title 17,
				chapter 38, subchapter 1.
(17) A
				lesser setback may be allowed in accordance with ARM
				17.30.1702.
(18) This setback applies unless the
				department has approved a smaller source-specific well isolation zone under
				Department Circular DEQ-20, Standard 1.8. In that case, the source specific
				well isolation zone distance applies.