CHAPTER 9
DEVELOPMENT REQUIREMENTS IN THE FLOODWAY
DEVELOPMENT REQUIREMENTS IN THE FLOODWAY
SECTION:
12-9-1: Uses Requiring Permits
12-9-2: General Requirements
12-9-3: Mining Of Material Requiring Excavation From Pits Or Pools
12-9-4: Railroad, Highway And Street Stream Crossings
12-9-5: Limited Filling For Road And Railroad Embankments
12-9-6: Buried Or Suspended Utility Transmission Lines
12-9-7: Storage Of Materials And Equipment
12-9-8: Domestic Water Supply Wells
12-9-9: Buried And Sealed Vaults For Sewage Disposal In Campgrounds And Recreational Areas
12-9-10: Public And Private Campgrounds
12-9-11: Structures Accessory Or Appurtenant
12-9-12: Construction Of Or Modifications To Surface Water Diversions
12-9-13: Flood Control And Stream Bank Stabilization Measures
12-9-14: Stream And Bank Restoration
12-9-15: Existing Residential And Non-Residential Buildings In The Floodway
Artificial obstructions including alterations and substantial improvements specifically listed in sections 12-9-3 to 12-9-15 may be allowed by permit within the floodway, provided the general requirements in section 12-9-2 and the applicable requirements in sections 12-9-3 to 12-9-15 are met (Ord. 16-3, 11-7-2016; amd. Ord. 16-3, 12-19-2022)
An application for a permit shall meet the following requirements:
A. All projects shall be designed and constructed to ensure that they do not adversely affect the flood hazard on other properties and are reasonably safe from flooding;
B. All projects shall assure that the carrying capacity of the Floodway is not reduced. All projects in the Floodway shall meet the following:
1. Demonstrate that the project does not increase the Base Flood Elevation by conducting an encroachment analysis certified by an engineer. A minimal or qualitative encroachment analysis may be accepted when the project or development does not require a structure, alteration of the Floodway, involve fill, grading, excavation or storage of materials or equipment but is also certified by an engineer to not exceed the allowable encroachment to the Base Flood Elevation; and
2. The allowable encroachment to the Base Flood Elevation is 0.00 feet, and no significant increase to the velocity or flow of the stream or water course unless approval of an alteration of the Regulated Flood Hazard Area pursuant to section 12-4-3 and an approved FEMA Conditional Letter of Map Revision occurs before permit issuance ((ARM 36.15.604) (ARM 36.15.505) (ARM 36.15.605(b)) (44 CFR 60.3(a)(3 and 4)) (44CFR 65.12(a)); and
C. An application for a Floodplain permit must also demonstrate the following factors are considered and incorporated into the design of the use or artificial obstruction in the Floodway:
1. The danger to life and property due to backwater or diverted flow caused by the obstruction or use ((MCA 76-5-406(1)) (ARM 36.15.216(2)(a)));
2. The danger that the obstruction or use may be swept downstream to the injury of others ((MCA 76-5-406(2)) (ARM 36.15.216(2)(b)));
3. The availability of alternative locations ((MCA 76-5-406(3)) (ARM 36.15.216(2)(c));
4. Construct or alter the obstruction or use in such manner as to lessen the flooding danger ((MCA 76-5-406(4)) (ARM 36.15.216(2)(d)));
5. The permanence of the obstruction or use and is reasonably safe from flooding ((MCA 76-5-406(5) (ARM 36.15.216(2e)));
6. The anticipated development in the foreseeable future of the area which may be affected by the obstruction or use ((MCA 76-5-406(6)) (ARM 36.15.216(2f)));
7. Relevant and related permits for the project have been obtained (44 CFR 60.3(a)(2));
8. 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 ((MCA 76-5-406(7)) (ARM 36.15.216(2)(g))); and
9. The safety of access to property in times of flooding for ordinary and emergency services (44CFR 60.22 (c)(7)). (Ord. 16-3, 11-7-2016; amd. Ord. 16-3, 12-19-2022)
Provided, in addition to the requirements of section 12-9-2, 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 (ARM 36.15.602(1)(a));
B. The excavation meets all applicable laws and regulations of other local and state agencies (ARM 36.15.602(1)(b)); and
C. Excavated material may be processed on site but is stockpiled outside the Floodway (ARM 36.15.602(1)(c)). (Ord. 16-3, 11-7-2016; amd. Ord. 16-3, 12-19-2022)
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