12-9-5: LIMITED FILLING FOR ROAD AND RAILROAD EMBANKMENTS:

Including other transportation related embankments not associated with stream crossings and bridges provided, in addition to the requirements of section 12-9-2, that:

   A..   The fill is suitable fill;

   B.   Reasonable alternate transportation routes outside the floodway are not available (ARM 36.15.602(3)); and

   C.   The encroachment is located as far from the stream channel as possible (ARM 36.15.602(3)). (Ord. 16-3, 11-7-2016; amd. Ord. 16-3, 12-19-2022)

12-9-6: BURIED OR SUSPENDED UTILITY TRANSMISSION LINES:

Provided, in addition to the requirements of section 12-9-2, that:

   A.   Suspended utility transmission lines are designed such that the lowest point of the suspended line is at least six (6) feet higher than the Base Flood Elevation (ARM 36.15.602(4));

   B.   Towers and other appurtenant structures are designed and placed to withstand and offer minimal obstruction to flood flows (ARM 36.15.602(4));

   C.   Alternatives such as alternative routes, directional drilling, and aerial crossings are considered when technically feasible; and

   D.   Utility transmission lines carrying toxic or flammable materials are buried to a depth of at least twice the calculated maximum scour depth determined by an engineer for the Base Flood (ARM 36.15.602(4)). (Ord. 16-3, 11-7-2016; amd. Ord. 16-3, 12-19-2022)

12-9-7: STORAGE OF MATERIALS AND EQUIPMENT:

Provided, in addition to the requirements of section 12-9-2, that:

   A.   The material or equipment is not subject to major damage by flooding and is properly anchored to prevent flotation or downstream movement (ARM 36.15.602(5)(a)); 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 (ARM 36.15.602(5)(b)). (Ord. 16-3, 11-7-2016; amd. Ord. 16-3, 12-19-2022)

12-9-8: DOMESTIC WATER SUPPLY WELLS:

Provided, in addition to the requirements of section 12-9-2, that:

   A.   They are driven or drilled wells located on ground higher than surrounding ground to assure positive drainage from the well (ARM 36.15.602(6));

   B.   They require no other structures (e.g. a well house) (ARM 36.15.602(6));

   C.   Well casings are water tight to a distance of at least twenty five (25) feet below the ground surface and the well casing height is a minimum of two (2) feet above the base flood elevation or capped with a watertight seal and vented two (2) feet above the base flood elevation ((ARM 36.15.602(6)));

   D.   Water supply lines have a watertight seal where the lines enter the casing (ARM 36.15.602(6));

   E.   All pumps and electrical lines and equipment are either of the submersible type or are adequately flood proofed (ARM 36.15.602(6)); and.

   F.   Check valves are installed on main water lines at wells and at all building entry locations ((44 CFR 60.3 (a)(5)) (ARM 36.15.602(6))). (Ord. 16-3, 11-7-2016; amd. Ord. 16-3, 12-19-2022)

12-9-9: BURIED AND SEALED VAULTS FOR SEWAGE DISPOSAL IN CAMPGROUNDS AND RECREATIONAL AREAS:

Provided, in addition to the requirements of section 12-9-2, demonstrate approval by Montana Department of Environmental Quality and local health and sanitation permits or approvals ((44 CFR 60.3(a)(6)) (ARM 36.15.602(7))). (Ord. 16-3, 11-7-2016; amd. Ord. 16-3, 12-19-2022)

12-9-10: PUBLIC AND PRIVATE CAMPGROUNDS:

Provided, in addition to the requirements of section 12-9-2, that:

   A.   Access roads require only limited fill and do not obstruct or divert flood waters (ARM 36.15.602(8));

   B.   The project meets the accessory structures requirements in this chapter;

   C.   No dwellings or permanent mobile homes are allowed (ARM 36.15.602(8));

   D.   Recreational vehicles and travel trailers are ready for highway use with wheels intact, with only quick disconnect type utilities and securing devices, and have no permanently attached additions (44 CFR 60.3(c)(14)); and

   E.   There is no large-scale clearing of riparian vegetation within 50 feet of the mean annual high water mark. (Ord. 16-3, 11-7-2016; amd. Ord. 16-3, 12-19-2022)

12-9-11: ACCESSORY STRUCTURES:

Structures accessory or appurtenant to permitted uses such as boat docks, loading and parking areas, marinas, sheds, emergency airstrips, permanent fences crossing channels that may impede or stop flows or debris, picnic shelters and tables and lavatories, that are incidental to a principal structure or use, provided in addition to the requirements of section 12-9-2, that:

   The structures are not intended for human habitation or supportive of human habitation (ARM 36.15.602(9));

   The structures will have low flood damage potential (ARM 36.15.602(9));

   The structures will, insofar as possible, be located on ground higher than the surrounding ground and as far from the channel as possible (ARM 36.15.602(9));

   The structures will be constructed and placed so as to offer a minimal obstruction to flood flows (ARM 36.15.602(9));

   Only those wastewater disposal systems that are approved under health and sanitation regulations are allowed;

   Service facilities within these structures such as electrical, heating and plumbing are flood proofed according to the requirements in chapter 12-10 of this title (ARM 36.15.602(9));

   The structures are firmly anchored to prevent flotation (ARM 36.15.602(9));

   The structures do not require fill and/or substantial excavation;

   The structures or use cannot be changed or altered without permit approval; and

   There is no clearing of riparian vegetation within 50 feet of the mean annual high water mark. (Ord. 16-3, 11-7-2016; amd. Ord. 16-3, 12-19-2022)

12-9-12: CONSTRUCTION OF OR MODIFICATIONS TO SURFACE WATER DIVERSIONS:

Provided, in addition to the requirements of section 12-9-2, that the design is reviewed and approved by an engineer and includes:

   A.   Measures to minimize potential erosion from a Base Flood (ARM 36.15.603(3)(b)); and

   B.   Designs and plans that demonstrate any permanent structure in the stream is designed to safely withstand up to the Base Flood considering the forces associated with hydrodynamic and hydrostatic pressures including flood depths, velocities, impact, ice buoyancy, and uplift forces associated with the Base Flood ((ARM 36.15.603(3)(c) ((CFR 60.3(a)(3) (CFR 60.3(d)(3))). (Ord. 16-3, 11-7-2016; amd. Ord. 16-3, 12-19-2022)

12-9-13: FLOOD CONTROL AND STREAM BANK STABILIZATION MEASURES:

Provided, in addition to the requirements of section 12-9-2, that the design is reviewed and approved by an engineer and constructed to substantially resist or withstand the forces associated with hydrodynamic and hydrostatic pressures, including flood depths, velocities, impact, ice, buoyancy, and uplift associated with the Base Flood. The design must also show compliance with the following applicable criteria ((CFR 60.3(a)(3) (CFR 60.3(d)(3)) (ARM 36.15.606)):

   A.   Levee And Floodwall Construction Or Alteration:

      1.   Must be designed and constructed with suitable fill and be designed to safely convey a Base Flood (ARM 36.15.606(1)(a));

      2.   Must be constructed at least 3 feet higher than the elevation of the Base Flood unless the levee or floodwall protects agricultural land only (ARM 36.15.606(2)(a));

      3.   Must meet state and federal levee engineering and construction standards and be publically owned and maintained if it protects structures of more than one landowner (ARM 36.15.505(1)(c)(ii)and (iii)); and

      4.   For any increase in the elevation of the Base Flood, an alteration of the Regulated Flood Hazard Area requires approvals pursuant to section 12-4-3.

   B.   Stream Bank Stabilization, Pier And Abutment Protection Projects:

      1.   Must be designed and constructed using methods and materials that are the least environmentally damaging yet practicable, and should be designed to withstand a Base Flood once the project’s vegetative components are mature within a period of up to 5 years or other time as required by the Floodplain Administrator. Once vegetation is mature and established it should not require substantial yearly maintenance after the initial period;

      2.   Materials for the project may be designed to erode over time but not fail catastrophically and impact others. Erosion, sedimentation, and transport of the materials may be designed to be at least similar in amount and rate of existing stable natural stream banks during the Base Flood;

      3.   Must not increase erosion upstream, downstream, across from or adjacent to the site in excess of the existing stable natural stream bank during the Base Flood (ARM 36.15.606(1)(b)); and

      4.   Materials for the project may include but are not limited to riprap, root wads, brush mattresses, willow wattles, natural woody debris or combinations of analogous materials.

   C.   Channelization Projects where the excavation and/or construction of an channel is for the purpose of diverting the entire or a portion of the flow of a stream from its established course, the project must:

      1.   Not increase the magnitude, velocity, or elevation of the Base Flood; and

      2.   Meet the requirements of section 12-9-13B (ARM 36.15.101(7)) (ARM 6.15.606(1)(c)).

   D.   Dams:

      1.   The design and construction shall be in accordance with the Montana Dam Safety Act and applicable safety standards; and

      2.   The project shall not increase flood hazards downstream either through operational procedures or improper hydrologic/hydraulic design (ARM 36.15.606(1)(d). (Ord. 16-3, 11-7-2016; amd. Ord. 16-3, 12-19-2022)