11 AAC 95.305. Culverts and other water crossing provisions

(a) An operator shall install a culvert on a forest road according to the following standards:

(1) a temporary culvert and the adjacent roadway must be constructed to pass or withstand the 25-year flood without damage; a permanent culvert and the adjacent roadway must be constructed to pass or withstand the 50-year flood without damage; any adjustment to these design standards must be determined in the field considering the characteristics of the drainage, the design life of the road, the importance of downstream resources, the type of construction techniques, and the likelihood of culvert or road failure;

(2) the size of the culvert must be determined in accordance with hydrologic engineering principles; a culvert may not be installed that is smaller than 12 inches in diameter or equivalent capacity; where culvert icing conditions are to be expected, other drainage designs such as open flumes buried in the road surface should be considered instead of culverts;

(3) for fish-bearing waters, the entrance, to the extent possible, and exit of a stream culvert must match the natural course of a stream channel; a culvert may not be perched at its inlet or outlet;

(4) a culvert must terminate on material that will not readily erode, such as riprap, the original streambed if stable, or other suitable materials;

(5) a change may not be made in the course or channel of anadromous fish waters catalogued under AS 41.14.870 without giving notice to the division and receiving written approval of the deputy commissioner; a change may not be made in the course or channel of other waters that are significant for protection of downstream water quality, without prior notice to the division;

(6) when a flume, downspout, downfall culvert, or similar structure is used to protect fill slopes or to return water to its natural course, the discharge point shall be protected from erosion by

(A) reducing the velocity of the water;

(B) using rock spillways, riprap, or splash plates; or

(7) for nonfish-bearing waters, the area of a stream bed from a culvert inlet to 50 feet upstream from the culvert inlet must be cleared of mobile slash or debris that may be expected to plug a culvert;

(8) to prevent or minimize sedimentation, the entrance of a relief culvert must have adequate and appropriate catch basins, consistent with physical features of the ground; a headwall must be used to direct ditch water into cross drains;

(9) a culvert must be of sufficient length to prevent road overlay materials from blocking an end of the culvert.

(b) A properly prepared and maintained ford may be used for an equipment crossing during a period of low water. If the ford crosses anadromous fish waters catalogued under AS 41.14.870 , written approval of the deputy commissioner is required. For other surface waters, prior notice to the division is required. A ford must cross a stream substantially perpendicular to the stream flow, and the approaches must be properly ballasted or otherwise stabilized to avoid sedimentation. Ford construction must comply with AS 41.14.840 .

History: Eff. 6/10/93, Register 126; am 6/24/2004, Register 170

Authority: AS 41.17.010

AS 41.17.055

AS 41.17.080

AS 41.17.098

Editor's note: As of Register 166 (July 2003), and acting under AS 44.62.125 (b)(6), the regulations attorney made technical changes to 11 AAC 95.305(a) (5) and (b), to reflect Executive Order 107 (2003). Executive Order 107 transferred functions related to protection of fish habitat in rivers, lakes, and streams from the Department of Fish and Game to the Department of Natural Resources.

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