Montana Administrative Register Notice 17-288 No. 19   10/15/2009    
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In the matter of the amendment of ARM 17.30.702, 17.36.101, 17.36.102, 17.36.103, 17.36 104, 17.36.323, 17.36.345, 17.36.911, 17.36.912, 17.36.914, 17.36.916, 17.36.918, 17.36.922, 17.38.101, 17.55.102, and the adoption of New Rules I and II pertaining to Department Circular DEQ-4 and gray water reuse


















TO:  All Concerned Persons


            1.  On June 25, 2009, the Board of Environmental Review published MAR Notice No. 17-288 regarding a notice of public hearing on the proposed amendment and adoption of the above-stated rules at page 968, 2009 Montana Administrative Register, issue number 12.


            2.  The board has amended ARM 17.30.702, 17.36.101, 17.36.102, 17.36.103, 17.36.345, 17.36.911, 17.36.912, 17.36.914, 17.36.916, 17.36.918, 17.36.922, and 17.55.102 exactly as proposed.  The board has amended ARM 17.36.104, 17.36.323, and 17.38.101 and adopted New Rules I (17.36.319) and II (17.36.919) as proposed, but with the following changes, stricken matter interlined, new matter underlined:


            17.36.104  APPLICATION--LOT LAYOUT DOCUMENT  (1) remains as proposed.

            (2)  The following information must be provided on the lot layout document.  Other information (e.g., percolation test results, soil profile descriptions) may be included on the lot layout document only if the document remains legible:

            (a) through (i) remain as proposed.

            (j)  information as set out in Table 1 for the specific water supply and wastewater systems in the subdivision.  All systems must be labeled as "existing" or "proposed."








Subdivisions served by nonmunicipal wells


Subdivisions served by  nonmunicipal




Subdivisions served by municipal water


Subdivisions served by municipal  wastewater systems

Existing and proposed wells and 100-ft setback










Water lines (suction and pressure)









Water lines (extension and connections)







Existing and proposed wastewater systems (drainfield, replacement area, and existing septic tanks)









Existing and proposed gray water irrigation systems









Percent and direction of slope across the drainfield







Sewer lines (extensions and connections),

gray water irrigation systems









Lakes, springs, irrigation ditches, wetlands and streams








Percolation test locations, if provided, keyed to result form






Soil pit locations keyed to soil profile descriptions








Ground water monitoring wells keyed to monitoring results form






Floodplain boundaries














Existing building locations













Road cuts and escarpments or slopes > 25%







Mixing zone boundaries and direction of ground water flow










            (1)  Minimum horizontal setback distances (in feet) shown in Table 3 of this rule must be maintained.  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.

            (2) through (4) and Table 3 remain as proposed.


            17.38.101  PLANS FOR PUBLIC WATER SUPPLY OR WASTEWATER SYSTEM  (1) and (2) remain as proposed.

            (3)  As used in this rule, the following definitions apply in addition to those in 75-6-102, MCA:

            (a) and (b) remain as proposed.

            (c)  "Gray water" is defined in 75-5-325, MCA.

            (c) through (k)(ii) remain as proposed, but are renumbered (d) through (l)(ii).

            (4) through (17) remain as proposed.


            NEW RULE I  (17.36.319)  GRAY WATER REUSE  (1) through (3) remain as proposed.

            (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) through (d) remain as proposed.

            (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 drinking water wells;

            (ii)  50 feet of non drinking water wells;

            (iii) through (v) remain as proposed, but are renumbered (ii) through (iv).

            (f) through (7) remain as proposed.

            (8)  If an existing gray water irrigation system is present in a proposed subdivision, the department shall review the adequacy of the system for the proposed use and the capability of the system to operate without risk to public health and without pollution of state waters.  Existing systems must comply with state and local laws and regulations, including permit requirements, applicable at the time of installation.


            NEW RULE II  (17.36.919)  GRAY WATER REUSE  (1) and (2) remain as proposed.

            (3)  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) through (d) remain as proposed.

            (e)  gray water irrigation may not occur within:

            (i)  100 feet of drinking water wells;

            (ii)  50 feet of non drinking water wells;

            (iii) through (v) remain as proposed, but are renumbered (ii) through (iv).

            (f) through (6) remain as proposed.


            3.  The following comments were received and appear with the board's responses:


ARM 17.36.104


            COMMENT NO. 1:  The proposed addition of gray water systems to the lot layout Table in ARM 17.36.104 should include both existing and proposed systems.

            RESPONSE:  This change has been made.  An additional sentence has also been added to New Rule I to clarify that existing gray water systems in subdivisions must be shown as properly functioning and in compliance with regulations applicable at the time of installation.


ARM 17.36.323


            COMMENT NO. 2:  The amendments to ARM 17.36.323 could imply that no setbacks apply to gray water irrigation systems.

            RESPONSE:  The proposed amendment to ARM 17.36.323 has been changed to clarify that New Rule I does contain setbacks for gray water irrigation systems.


ARM 17.38.101


            COMMENT NO. 3:  The public water and sewer rules should include a definition of "gray water."

            RESPONSE:  A definition has been included in the proposed amendments to ARM 17.38.101.




            COMMENT NO. 4:  The rules are inconsistent about kitchen waste.  New Rule I prohibits use of gray water from kitchens for irrigation except where waste segregation systems are used.  Kitchen gray water irrigation should be either considered safe in all situations or considered unsafe and prohibited for all uses.

            RESPONSE:  Kitchen gray water can contain a higher percentage of biological oxygen demand (BOD) than nonkitchen gray water, and it can contain pathogens not found in other gray water waste streams.  The threat of pathogen infection from gray water irrigation is mitigated by the subsurface disposal requirements in the new rules and Circular, but further restrictions are warranted to minimize exposure to the pathogens in kitchen gray water.  Consequently, the rules and Circular prohibit use of kitchen gray water for irrigation except where there is no alternative, as is the case where waste segregation systems (composting or incinerating toilets) are used.


            COMMENT NO. 5:  In New Rules I and II, the requirement that there be a 50-foot separation between nondrinking water wells and gray water systems is not consistent with the setback in the subdivision rules and the state minimum standards for county septic rules.  The other rules require 100 feet between drainfields and all wells, whether for drinking water or not.  Any well is a conduit to the aquifer, and we should not provide less protection for irrigation wells.

            RESPONSE:   New Rules I and II have been changed to be consistent with the drainfield-well setbacks in ARM 17.36.323 and ARM 17.36.918.


            COMMENT NO. 6:  A commentor raised a question about how the new rules and Circular would apply to a homeowner with a parcel entirely within the floodplain who intended to fill the floodplain and irrigate in the fill area with gray water. 

            RESPONSE:  The same floodplain restrictions applicable to all DEQ-4 systems apply to gray water irrigation.  See New Rule I(4)(c) and New Rule II(3)(c).  Use of fill for new gray water irrigation systems is not prohibited, however, in order to allow irrigation in raised beds.  The rules do require that there 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.  See New Rule I(4)(d) and New Rule II(3)(d).




            COMMENT NO. 7:  Who enforces the gray water rules?

            RESPONSE:  Under the Sanitation in Subdivisions Act, Title 76, Chapter 4, MCA, DEQ reviews proposed water supply, wastewater disposal, solid waste, and storm water facilities in proposed subdivisions.  Since gray water is wastewater, DEQ will review proposed gray water irrigation systems in subdivisions under the Sanitation Act.  DEQ has authority to bring enforcement actions for violations of the conditions of a Sanitation Act approval.  The gray water rules and Circular will also be administered by local health departments under their authority to issue permits for wastewater systems.  The local health departments can bring enforcement actions for violations of the local permit requirements.


            COMMENT NO. 8:  Filters should be required on all gray water systems.

            RESPONSE:  The proposed gray water irrigation chapter in Department Circular DEQ-4 recommends, but does not require, that gray water systems include a filter to prevent the buildup of solids and to insure proper system functioning.  Section 3.5.  If no filter is included in the design, the Circular requires that three valved irrigation zones be used to rotate the distribution of gray water between zones.  The alternating irrigation zone design is based on the Uniform Plumbing Code, and the advantage is that no filtration is required.  In order to allow for a variety of design options, filters will not be made mandatory for all systems.


            COMMENT NO. 9:  In the proposed new chapter for Department Circular DEQ-4, the introductory system description paragraph does not mention gray water from kitchen sinks, but Section 1.5 allows irrigation using kitchen gray water when waste segregation systems are used. 

            RESPONSE:  The system description paragraph has been modified to include a reference to kitchen gray water for waste segregation systems.


            COMMENT NO. 10:  In the proposed new chapter for Department Circular DEQ-4, the introductory paragraph says that gray water must meet all applicable provisions in the Circular, but Section 1.2 says that gray water irrigation that meets the requirements of this chapter are not subject to the other chapters in the Circular.  This appears to be contradictory.

            RESPONSE:  Because gray water is wastewater, gray water disposal in general is subject to all the requirements in the Circular applicable to wastewater.  However, if gray water is used for irrigation and the irrigation meets the requirements in the new Circular chapter, the irrigation is not subject to the requirements in the other chapters in the Circular, except where they are specifically referenced.


            COMMENT NO. 11:  A definition of "Gray water irrigation system" should be included.

            RESPONSE:  A definition of "gray water" exists in statute at 75-5-325, MCA, and a definition of "irrigation system" is in the proposed new Circular chapter.  The requested definition would not add to these existing definitions except to specify that irrigation must be subsurface.  The requirement that irrigation be subsurface is already included in the new rules and Circular.


            COMMENT NO. 12:  The definition of "gray water" should be changed to include laundry wastewater and exclude industrial wastewater.

            RESPONSE:  The definition of "gray water" is the definition set by statute at 75-5-325(1), MCA.  The rules can not alter the statutory definition.


            COMMENT NO. 13:  The rules should specify how deep the subsurface irrigation lines must be buried.

            RESPONSE:  The proposed new chapter in Department Circular DEQ-4 has been modified in response to this comment to require a burial depth of at least six inches below ground surface.


            COMMENT NO. 14:  The rules should prohibit more than one gray water irrigation system on a lot.

            RESPONSE:  This restriction is not necessary.  If multiple systems are proposed, each system must meet all the requirements in the rules and Circular.  These requirements are protective of public health and the environment. 


            COMMENT NO. 15:  Backflow prevention should be required to prevent black water from going into the gray water irrigation system.

            RESPONSE:  A change has been made to Section 2.6 of the new chapter of the Circular to require backflow prevention.


            COMMENT NO. 16:  A minimum horizontal setback from steep slopes and roadcuts should be required to prevent seepage of gray water to the surface.

            RESPONSE:  In order to allow use of gray water irrigation in raised beds, the Circular does not contain a slope setback.  In reviewing designs of gray water systems the reviewing authority will apply Section 1.8 of the new chapter of the Circular, which prohibits ponding or surfacing of gray water.


            COMMENT NO. 17:  For gray water systems approved to accept kitchen gray water, a settling tank should be required to prevent clogging of the filter.

            RESPONSE:  To allow flexibility in design, the Circular does not require a settling tank.  A provision will be added to Section 4.1 to advise owners about the possibility of increased maintenance for systems using kitchen gray water.


            COMMENT NO. 18:  The rules should allow for use of irrigation with sewage effluent that has been treated with a sand filter followed by a bark filter, or an infiltrator filled with pea gravel and planted with appropriate plants.

            RESPONSE:  The use of treated sewage effluent, which includes toilet waste, for irrigation is outside the scope of this rulemaking.


            COMMENT NO. 19:  The managing entity of a public sewer system should be contacted before system users divert their gray water streams to irrigation.

            RESPONSE:  Section 1.11 of the new chapter in Department Circular DEQ-4 requires that the managing entity of the public wastewater system give written approval for a system user's proposed use of gray water for irrigation.


            COMMENT NO. 20:  Why does the proposed Circular require that gray water surge tanks be covered?

            RESPONSE:  Section 3.4.3 requires that surge tanks in gray water irrigation systems be covered.  This requirement protects the owner and others from exposure to gray water and helps ensure that no other items or liquids are added to the system.


            COMMENT NO. 21:  Section 3.4.4 of the new chapter in Department Circular DEQ-4 states that the minimum capacity of surge tanks must be 50 gallons.  The commentor believes this is too small.

            RESPONSE:  This is the minimum size specified for gray water surge tanks in the Uniform Plumbing Code.  A smaller tank is preferable to avoid long storage times, as unpleasant odors may develop.


            COMMENT NO. 22:  Section 3.4.6 of the new chapter in Department Circular DEQ-4 requires overflows from surge tanks to be connected to the "building drain, building sewer, or septic tank, if any."  Building drains should not be connected to any wastewater treatment system.

            RESPONSE:  The commentor may be referring to floor drains.  The intent of this section is to require that the gray water surge tank overflow be connected to the sewer that serves the building.  The term "building drain" has been removed to eliminate any confusion with floor drains that may not be connected to sewer.

            COMMENT NO. 23:  A new paragraph should be added to the Circular to require that counties attach any new gray water system design to the original septic permit.

            RESPONSE:  The counties already have systems in place to track multiple systems on single lots, and gray water systems would be handled the same way.


            COMMENT NO. 24:  Are gray water irrigation systems subject to United States Environmental Protection Agency (EPA) permit requirements for Class V injection wells?

            RESPONSE:  Gray water irrigation systems may require a permit from EPA in some situations.  The forward in Department Circular DEQ-4 states:  "Users of these standards need to be aware that subsurface wastewater treatment systems are considered by the Environmental Protection Agency to be Class V injection wells and may require associated permits."  Users are encouraged to contact EPA for further information.


            COMMENT NO. 25:  Has consideration been given to the fact that the gray water is alkaline and may interact with certain soils?

            RESPONSE:  Continued irrigation with gray water may cause a buildup of salts in certain soils.  The extent to which this occurs depends not only on soils but on the types of soaps used, whether water softeners are included, and background water quality.  The variety of factors that contribute to this condition make it difficult to regulate.  In an effort to inform homeowners about this and other aspects of gray water irrigation, a fact sheet is being developed.  The fact sheet will include a reminder that high salinity water can cause degradation of clay soils and may be harmful to some plants.


            COMMENT NO. 26:  Has consideration been given to the fact that gray water reuse through irrigation may limit the ability of a subdivision developer to obtain water right mitigation credits?

            RESPONSE:  If a subdivision developer has a ground water appropriation in a closed surface water basin, the developer may be required to mitigate any impacts the proposed well has on surface water.  In some cases, wastewater return flows can be given credit as surface water mitigation.  Gray water used for irrigation is consumed by the plants and would probably not receive mitigation credit.  The determination of allowable mitigation credits is a matter for the Department of Natural Resources and Conservation.


Reviewed by:                                     BOARD OF ENVIRONMENTAL REVIEW




/s/ James M. Madden                          By:  /s/ Joseph W. Russell                                 

JAMES M. MADDEN                                   JOSEPH W. RUSSELL, M.P.H.

Rule Reviewer                                               Chairman


Certified to the Secretary of State, October 5, 2009.


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