36.15.602    USES REQUIRING PERMITS

In addition to the uses allowed under ARM 36.15.601, the following artificial obstructions may be permitted within the designated floodway subject to the issuance of a permit by the permit issuing authority under the conditions set forth in this rule and ARM 36.15.603 and 36.15.604:

(1) excavation of material from pits or pools provided that:

(a) a buffer strip of undisturbed land of sufficient width to prevent flood flows from channeling into the excavation is left between the edge of the channel and the edge of the excavation;

(b) the excavation meets all applicable laws and regulations of other local and state agencies; and

(c) excavated material is stockpiled outside the designated floodway;

(2) railroad, highway, and street stream crossings provided that the crossings are designated to offer minimal obstruction to flood flow;

(3) limited filling for highway, street, and railroad embankments not associated with stream crossings provided that:

(a) reasonable alternative transportation routes outside the designated floodway are not available; and

(b) such floodway encroachment is located as far from the stream channel as possible;

(4) Buried or suspended utility transmission lines provided that:

(a) suspended utility transmission lines are designed such that the lowest point of the suspended line is at least 6 feet higher than the elevation of the base flood;

(b) towers and other appurtenant structures are designed and placed to withstand and offer minimal obstruction to flood flows; and

(c) utility transmission lines carrying toxic or flammable materials are buried to a depth at least twice the calculated maximum depth of scour for the base flood. The maximum depth of scour may be determined from any of the accepted hydraulic engineering methods, but the final calculated figure shall be subject to approval by the permit issuing authority;

(5) storage of materials and equipment provided that:

(a) the material or equipment is not subject to major damage by flooding and is properly anchored to prevent flotation or downstream movement; or,

(b) the material or equipment is readily removable within the limited time available after flood warning. Storage of flammable, toxic, or explosive materials shall not be permitted;

(6) domestic water supply wells provided that:

(a) they are driven or drilled wells located on ground higher than surrounding ground to assure positive drainage from the well;

(b) well casings are watertight to a distance of at least 25 feet below the ground surface;

(c) water supply and electrical lines have a watertight seal where the lines enter the casing;

(d) all pumps and electrical lines and equipment are either of the submersible type or are adequately floodproofed; and

(e) check valves are installed on main water lines at wells and at all building entry locations;

(7) buried and sealed vaults for sewage disposal in recreational areas provided that they meet applicable laws and

standards administered by the department of health and environmental sciences;

(8) Public or private campgrounds provided that:

(a) access roads require only limited fill and do not obstruct or divert flood waters; and,

(b) no dwellings or permanent mobile homes are allowed;

(9) structures accessory to the uses permitted in this subsection such as boat docks, marinas, sheds, permanent fences crossing channels, picnic shelters and tables, and toilets provided that:

(a) the structures are not intended for human habitation;

(b) the structures will have a low flood damage potential;

(c) the structures will insofar as possible be located on ground higher than the surrounding ground and as far from the channel as possible;

(d) the structures will be constructed and placed so as to offer a minimal obstruction to flood flows;

(e) the structures will be firmly anchored to prevent flotation; and,

(f) service facilities within these structures such as electrical, heating, and plumbing facilities are floodproofed in accordance with ARM 36.15.901 through 36.15.903;

(10) all other artificial obstructions not specifically listed in this subsection or in ARM 36.15.606, not allowed under ARM 36.15.601, and not prohibited under ARM 36.15.605.

History: Sec. 76-5-208, MCA; IMP, Sec. 76-5-404 through 76-5-406, MCA; NEW, Eff. 9/4/74; AMD, 1989 MAR p. 1665, Eff. 10/27/89.