18 AAC 72.520 - Separation distance requirements

(a) A person who installs or modifies a conventional wastewater system must ensure that all existing and new components meet the minimum separation distances set out in 18 AAC 72.100 for private water systems, in 18 AAC 80 for public water systems, and this section.

(b) The minimum separation distance is 100 feet between the mean annual high water level of a lake, river, stream, spring, or slough, or the mean higher high water level of tidally influenced coastal waters and a septic tank, soil absorption system, lift station, or sewer manhole, measured horizontally from nearest edge to nearest edge.

(c) The minimum horizontal separation distance is 50 feet between any part of the absorption field and a slope greater than 25 percent, whether man-made or natural, with a vertical drop in surface height greater than 10 feet.

(d) The minimum vertical separation distance between the bottom of the distribution media in a conventional soil absorption system and

(1) the annual high water table is four feet; and

(2) an impermeable soil horizon such as bedrock, clay, permafrost, or other soils that percolate slower than 120 minutes per inch is six feet.

(e) The minimum horizontal separation distance between the distribution media in adjacent fields is six feet or two times the depth of media, whichever is greater.

(f) The minimum horizontal separation distance between a septic tank and an absorption field is five feet.

(g) The department will require a greater separation distance than what is required under, (a) - (f) of this section if the department determines that a greater separation distance is necessary to protect surface water, groundwater, or a private water system. The department will base its decision on soil classifications, groundwater conditions, surface topography, geology, past experience, or other factors relevant to the protection of surface water, groundwater, or drinking water.

Notes

18 AAC 72.520

Eff. 10/1/2023, Register 247, October 2023

Authority:AS 44.46.020

AS 44.46.025

AS 46.03.020

AS 46.03.050

AS 46.03.100