§ 11-1-76 GENERAL REQUIREMENTS.

   An application for a permit must demonstrate the following goals and criteria are considered and incorporated into the design of any use or artificial obstruction in the floodway requiring a permit.

   (A)   All projects in the floodway where specifically required herein as requiring an encroachment analysis, must undergo a thorough hydrologic and hydraulic analysis prepared by an engineer to demonstrate their effect on flood flows, velocities and the base flood elevation.

   (B)   A conditional approval from FEMA of any proposed increase of more than zero (0.00) feet in the base flood elevation must accompany the application. An application for a FEMA conditional letter of map revision approval requires a supporting encroachment analysis.

   (C)   The maximum allowable increase to the base flood elevation is one-half foot (0.50), unless approval of an alteration of the regulated flood hazard area pursuant to §§ 11-1-45 through 11-1-47 of this chapter occurs with approval of the variance pursuant to §§ 11-1-130 through 11-1-135 of this chapter:

      (1)   Projects must assure that the carrying capacity of the altered or relocated watercourse is maintained;

      (2)   Projects must be designed and constructed to ensure that they do not increase the flood hazard on other properties and be reasonably safe from flooding;

      (3)   The danger to life and property due to backwater or diverted flow caused by the obstruction or use;

      (4)   The danger that the obstruction or use may be swept downstream to the injury of others;

      (5)   The availability of alternative locations;

      (6)   The construction or alteration of the obstruction or use in such manner as to lessen the flooding danger;

      (7)   The permanence of the obstruction or use;

      (8)   The anticipated development in the foreseeable future of the area which may be affected by the obstruction or use;

      (9)   Relevant and related permits for the project have been obtained;

      (10)   Projects must conform to the additional minimum standards and provisions of this chapter as specified for the use or artificial obstruction specified herein;

      (11)   Such other factors as are in harmony with the purposes of these regulations, the Montana Floodplain and Floodway Management Act and the accompanying Administrative Rules of Montana; and

      (12)   The safety of access to property in times of flooding for ordinary and emergency services is subject to other more stringent regulations.

(Ord. 2013-01, passed 1-30-2013)

Federal law reference:

   Encroachments and community considerations, see 44 C.F.R. § 60.3

   Planning considerations for flood-prone areas, see 44 C.F.R. § 60.22

   Revision of flood insurance maps, see 44 C.F.R. § 65.12

Statutory reference:

   Alteration of floodplains, see ARM 36.15.505

   Minimum criteria for permits, see ARM 36.15.604

   Permit criteria, see ARM 36.15.216(2)

   Prohibited uses, see ARM 36.15.605(b)

   Variance request considerations, see MCA 76-5-406

§ 11-1-77 MINING OF MATERIAL REQUIRING EXCAVATION FROM PITS OR POOLS.

   Mining of materials requiring excavation from pits or pools may be permitted; provided that:

   (A)   A buffer strip of undisturbed land of sufficient width as determined by an engineer 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 may be processed on site, but is stockpiled outside the floodplain.

(Ord. 2013-01, passed 1-30-2013)

Statutory reference:

   Mining of material requiring excavation from pits or pools, see ARM 36.15.602(1)

§ 11-1-78 RAILROAD, HIGHWAY AND STREET STREAM CROSSINGS.

   Railroad, highway and street stream crossings may be permitted; provided that:

   (A)   Crossings are designed to offer minimal obstructions to the flood flow;

   (B)   Where failure or interruption of public transportation facilities would result in danger to public health or safety and where practicable and in consideration of FHWA Federal-Aid Policy Guide, 23 C.F.R. part 650A:

      (1)   Bridge lower chords shall have freeboard to at least two feet above the base flood elevation to help pass ice flows, the base flood discharge and any debris associated with the discharge; and

      (2)   Culverts are designed to pass the base flood discharge and maintain at least two feet freeboard on the crossing surface.

         (a)   If possible, normal overflow channels are preserved to allow passage of sediments to prevent aggradations;

         (b)   Mid stream supports for bridges, if necessary, have footings buried below the maximum scour depth; and

         (c)   An encroachment analysis is prepared by an engineer.

(Ord. 2013-01, passed 1-30-2013)

Statutory reference:

   Uses requiring permits, see ARM 36.15.602