18 AAC 72.020. Separation distances

(a) A person who builds or installs a sewer, private sewer line, onsite system, or domestic wastewater treatment works shall comply with the applicable minimum separation distances set out

(1) in 18 AAC 80.020 for a public water system, unless the department has approved a lesser separation distance under that section; or

(2) in (c) of this section for a private water system.

(b) The minimum separation distance between the mean annual high water level of a lake, river, stream, spring, or slough, or the mean higher high water level of coastal waters, and a lift station, holding tank, septic tank, soil absorption system, seepage pit, pit privy, or other wastewater collection, treatment, or disposal system is 100 feet, measured horizontally.

(c) Except as otherwise provided in this section, the minimum separation distance between the source of the drinking water for a private water system and a

(1) domestic wastewater treatment works, onsite disposal system, pit privy, sewer manhole and lift station, or sewer cleanout is 100 feet, measured from the nearest edge of the treatment works, disposal system, pit privy, manhole, lift station, or cleanout to the private drinking water source;

(2) community sewer line, holding tank, sanitary landfill, industrial discharge line, or other potential source of contamination, such as domestic animal or agricultural waste, is 75 feet, measured from the nearest edge of the community sewer line, holding tank, sanitary landfill, industrial discharge line, or other potential source of contamination to the private drinking water source; or

(3) private sewer line, petroleum lines and storage tanks, or drinking water treatment wastes, such as backwash water from filters and water softeners and reject water from reverse osmosis units, is 25 feet; the minimum separation distance for petroleum storage tanks does not apply to

(A) tanks that contain propane; or

(B) above-ground storage tanks or drums that, in the aggregate, have a storage capacity of less than 500 gallons of petroleum products, and that store only petroleum products necessary for the operation and maintenance of pumps, power generation systems, or heating systems associated with a potable water well or other potable water source; for purposes of this subparagraph, "petroleum products" refers to fuel and lubricants.

(d) The department will require a greater separation distance than that required by (b) or (c) of this section if the department determines that distance to be necessary to protect surface water, groundwater, or a drinking water source. The department will make this decision after considering soil classifications, groundwater conditions, surface topography, geology, past experience, or other factors relevant to protection of surface water, groundwater, or drinking water.

(e) A request for a waiver of the separation distance required by (b) or (c) of this section, and for approval of a lesser separation distance, must include a report for each waiver that is sought, including multiple waivers for a single project. The report required under this subsection must

(1) be sealed by a registered engineer; the department will waive this requirement if the department determines that

(A) the site of the proposed system is remote from a community with access to professional engineering services; and that the resulting cost of bringing a registered engineer to the site would be overly burdensome; and

(B) public health, public and private water systems, and the environment are adequately protected without this requirement;

(2) justify the lesser distance and explain how the lesser distance does not threaten public health, public and private water systems, or the environment;

(3) describe soil classifications, groundwater conditions, surface topography, geology, and other environmental conditions that would assist the department in establishing a lesser separation distance; and

(4) include a set of plans, consisting of

(A) record drawings if the department determines them necessary to evaluate the request;

(B) an accurate description, including the location, of potential sources of contamination, surface water, groundwater, and existing or potential drinking water sources in the area; and

(i) address the physical and environmental conditions listed in (3) of this subsection; and

(ii) will prevent contamination of the surface water, groundwater, or drinking water sources identified in (B) of this paragraph at the lesser distance; and

(D) other information the department determines to be necessary to assess the effect of a lesser distance upon public health, public and private water systems, and the environment.

(f) In accordance with 18 AAC 72.060, the department will approve a waiver of the separation distance required by (b) or (c) of this section if the department finds, after review of the report submitted under (e) of this section, that a lesser separation distance does not threaten public health or the environment and protects surface water, groundwater, and existing or potential drinking water sources. As necessary to protect public health and the environment, and to protect surface water, groundwater, and existing or potential drinking water sources, the department will require changes to system design as a condition of approval, including increased depth of grout and changes to the pipe material, pipe bedding, joints, and pipe strength.

(g) A person may not install

(1) a septic tank or soil absorption system directly above or below a water line at any distance, or within 10 horizontal feet of a water line; or

(2) a sewer line directly above or below at any distance, or within 10 horizontal feet of a water line, unless

(A) the required location or separation distance cannot be met because of the site configuration, the system design, or the presence of other obstacles that have regulated separation distance requirements;

(B) the sewer line is designed and constructed in a manner equivalent to the requirements for a potable water pipe, and

(i) is pressure tested to ensure watertightness; or

(ii) is enclosed in a carrier pipe of similar strength and rating as the actual pipe, or of a strength and rating approved by the department as protective of public health, public and private water systems, and the environment;

(D) at locations where sewer and water lines must cross,

(i) the sewer line is installed below the water line to the maximum length possible until existing appurtenances, elevations, or depth-of-cover requirements prohibit such installation;

(ii) the sewer line uses a bedding that is specially designed to protect the integrity of the sewer line in places where the elevation of a water line is below a sewer line;

(iii) the sewer line joints are at least nine feet from the water line joints; and

(iv) the sewer line is at least 18 vertical inches from a water line.

(h) Upon determining that a waiver will not threaten public health, public and private water systems, or the environment, the department will waive the requirements of (g) of this section in accordance with 18 AAC 72.060

(1) for a utilidor, if the water line is above the sewer line, and

(A) for an above-ground utilidor, the utilidor will not flood if pipe failure occurs; or

(B) for an underground utilidor, the utilidor is drained to a low point within the utilidor and has an automatic pumping and alarm system; or

(2) on a case-by-case basis, if design plans, reports, or drawings supporting a request for a lesser vertical and horizontal separation distance between water and sewer lines or for other configurations are sealed by a registered engineer.

(i) A person may not install a pit privy in an area subject to flooding. The vertical separation between the lowest point of a pit privy and the water table, measured during the season of the year with maximum water table elevation, must be at least four feet.

(j) The minimum vertical separation between the lowest part of a conventional soil absorption system and

(1) the water table, as measured during the season of the year with maximum water table elevation, must be at least four feet; and

(2) underlying bedrock, clay, or other impermeable strata must be at least six feet.

History: Eff. 4/1/99, Register 149; am 3/25/2001, Register 157

Authority: AS 44.46.020

Editor's note: Examples of the bedding described in 18 AAC 72.020(g) (2)(D)(ii) include Type 4 or Type 5 bedding described in American Water Works Association Standard C600-93, listed in 18 AAC 72.070(c) (2).

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