Title 18 . Environmental Conservation

Chapter 80 . Administrative Enforcement

Section 20. Minimum separation distances

18 AAC 80.020. Minimum separation distances

(a) A person may not construct, install, maintain, or operate a public water system unless the minimum separation distances in Table A, in this subsection, are maintained between a potential source of contamination and a drinking water source for the public water system.

TABLE A Minimum Separation Distances a Between Drinking Water Sources and Potential Sources of Contamination (Measured horizontally in feet) Potential Sources of Contamination Type of Drinking Water System Class A & Class B Class C Public Public Water Water Systems Systems Wastewater treatment works b ; wastewater disposal system b ; pit privy b , sewer manhole, lift station, cleanout 200 150 Community sewer line, holding tank b , other potential sources of contamination c 200 100 Private sewer line, petroleum lines and storage tanks d , drinking water treatment waste e 100 75

Notes to Table A: a These minimum distances will be expanded, or additional monitoring will be required under 18 AAC 80.020(b) and (e)(2). b Distance to a drinking water source is measured from the nearest edge of the drinking water source to the nearest edge of the potential source of contamination. c Other potential sources of contamination include sanitary landfills, domestic animal and agricultural waste, and industrial discharge lines. d The minimum separation distances for petroleum storage tanks do not apply to tanks that contain propane, or to 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 source. e Drinking water treatment wastes include the backwash water from filters and water softeners, and the reject water from reverse osmosis units. _____________________________________________________________________________

(b) The department will require a greater separation distance than that required by Table A in (a) of this section if the department determines that additional distance is 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.

(c) A request for a waiver under (d) of this section must include the fee required under 18 AAC 80.1910(b)(11) and 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; a report for a Class C public water system does not have to be sealed by a registered engineer if the department determines that

(A) the site of the proposed Class C public water 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 and public and private water systems are adequately protected without this requirement;

(2) justify the lesser distance and explain how the lesser distance does not threaten public health;

(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 and existing or potential drinking water sources in the area;

(C) the details of the system design that

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

(ii) will prevent contamination of the 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 the public water system.

(d) Upon receiving a request that conforms with (c) of this section, the department will approve a waiver of the separation distance required by Table A in (a) of this section if the department finds, after review of the report submitted under (c) of this section, that a lesser separation distance does not threaten public health, and protects existing or potential drinking water sources. As necessary to protect public health 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.

(e) If the department approves a lesser separation distance under this section, the owner or operator shall

(1) ensure that the system

(A) continues to meet the primary MCLs set by 18 AAC 80.300(b) ; and

(B) meets the secondary MCLs set by 18 AAC 80.300(c) , if required under 18 AAC 80.300(d) ; and

(2) perform additional monitoring as the department determines necessary to ensure adequate public health protection.

(f) A person may not install a water line

(1) directly above or below a septic tank or soil absorption system at any distance;

(2) within 10 horizontal feet of a septic tank or soil absorption system; or

(3) directly above or below at any distance, or within 10 horizontal feet of a sewer 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 water systems, and the environment;

(C) the water line is in a separate trench from the sewer line; and

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

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

(ii) the sewer line uses a Type 4 or Type 5 bedding described in ANSI/AWWA Standard C600-93, adopted by reference in 18 AAC 80.010(b) to protect the integrity of the sewer line in places where the elevation of a water line is below a sewer line;

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

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

(g) Upon determining that a waiver will not threaten the public health, the public water system, or the environment, the department will waive the requirements of (f) this section after payment of the fee required by 18 AAC 80.1910(b)(11)

(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.

History: Eff. 10/1/99, Register 151

Authority: AS 44.46.020

AS 46.03.020

AS 46.03.050

AS 46.03.070

AS 46.03.710

AS 46.03.720

Editor's note: Information about how to review or obtain the reference materials referred to in this section is in the editor's note to 18 AAC 80.010.