Title 11 . Natural Resources

Chapter 95 . (No Regulations Filed)

Section 300. Bridge standards

11 AAC 95.300. Bridge standards

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

(1) a temporary bridge and the adjacent roadway must be constructed to pass or withstand the 25 year flood without damage; a permanent bridge 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 and stream crossing, the design life of the bridge, the importance of downstream resources, the type of construction techniques, and the likelihood of bridge failure during flood; an operator shall, as necessary, minimize potential flood damage to the structure and to downstream water quality and fish habitat by installing relief culverts through approach roads or by other means;

(2) one end of each new permanent log or wood bridge must be firmly anchored;

(3) an earth embankment constructed for use as a bridge approach must be protected from erosion by using planted or seeded ground cover, bulkheads, rock riprap, retaining walls, or other equally effective means;

(4) on a rock-decked bridge, curbs must be installed to contain road surface material, and a filter fabric must be laid underneath the material to prevent it from falling within the ordinary high water marks of the water body;

(5) a snow ramp or ice bridge must be constructed only of snow, ice, and cribbing, and must be largely free of soil and organic mat; it must be constructed to go out with natural ice breakup, or it must be breached and the cribbing removed when feasible before breakup to protect downstream structures, water quality, and fish habitat;

(6) a bridge must be installed to provide fish passage in accordance with AS 41.14.840 ;

(7) in deep V-notches or in drainages where a culvert may require substantial fill, a bridge is the preferred crossing structure, if feasible;

(8) a bridge must be installed in such a way as to minimize disturbance to the bed and banks of a stream.

(b) In addition to the requirements of (a) of this section, when installing a new bridge or replacing an existing bridge on a forest road that crosses anadromous fish waters, the installation must be in accordance with the standards set out in (c) of this section. In anadromous fish waters catalogued under AS 41.14.870 , an operator may not cross the water body with equipment, install a bridge or conduct excavation for bridges, place sills or abutments, or place stringers or girders within the ordinary high-water marks without prior written approval from the deputy commissioner. If prior written approval is required by the deputy commissioner under AS 41.14.870 , an operator shall comply with that deputy commissioner's requirements instead of the standards of (c) of this section.

(c) When installing a bridge over anadromous waters that have not been catalogued under AS 41.14.870 , an operator shall:

(1) locate a bridge where the banks are stable;

(2) locate a bridge on a straight reach of stream;

(3) locate a bridge where the bank and approach characteristics are suitable;

(4) schedule bridge building activity to occur during a period that will avoid or reduce adverse impact on fish; and

(5) where feasible, avoid the use of center supports.

(d) An operator may not narrow an anadromous stream between its ordinary high water marks.

(e) For water body types in Region III, a crossing may be made on natural ice. Natural ice thickness may be augmented if site-specific conditions, including water depth, are sufficient to protect fish habitat. In determining whether conditions are sufficient to protect fish habitat, the state forester will consider whether augmented ice thickness is likely to

(1) cause freezedown into gravels used for spawning or fish overwintering habitat,

(2) cause bed scouring that disturbs gravels used for fish spawning or fish overwintering habitat;

(3) excessively reduce the quality or volume of fish overwintering habitat; or

(4) adversely alter stream flow patterns above or below the crossing.

(f) In this section, "augmentation"

(1) means a technique to increase the freezing depth of natural ice; and

(2) includes any of the following:

(A) adding water or ice to the surface;

(B) removing snow.

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 95.300, 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.