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Home My WebLink About013 - Appendix J - Floodplain Design Narrative MONTANA | WASHINGTON | IDAHO | NORTH DAKOTA | PENNSYLVANIA 406.586.0277 tdhengineering.com 234 East Babcock Street Suite 3 Bozeman, MT 59715 July 19, 2024 RE: CANOPY HOTEL BOZEMAN FLOODPLAIN DEVELOPMENT STRATEGY NARRATIVE The following narrative is intended to summarize how the Canopy Hotel Bozeman project intends to follow the City’s floodplain development regulations for a non-residential building to be located within portions of the 100-yr regulatory floodplain. A new commercial hotel building is proposed at the northeast corner of S. Rouse Avenue and E. Babcock Street. The existing building at the site will be demolished and the proposed building will encroach upon the 100-yr floodplain fringe of Bozeman Creek with outdoor sidewalk and streetscape improvements proposed within the regulatory floodway boundary. The property was surveyed by TD&H Engineering in July 2023 and a site-specific delineation was completed in accordance with BMC 38.600.130 to determine where the base flood elevation intersects natural ground at the site (see attached floodplain exhibit). The west end of the proposed building will encroach on both the georeferenced and delineated flood fringe boundary where it will extend to the Rouse and Babcock Street frontages. No building elements will encroach into the regulatory floodway. T he upstream corner of the building at the corner of Babcock and Rouse was used to determine a project BFE = 4814.3 (See attached BFE calculations). The main floor of the building, including the entrances, will be elevated on a concrete foundation to an elevation of 4816.5 (2.2 feet above the BFE). Areas around the building will be stabilized with hardscape and landscaping elements with finished grade elevations nearly at or below the existing ground surface to connect with the adjacent street curbs and alley to the north. Basement parking level floors will be located below the base flood elevation and will be floodproofed and designed in accordance with FEMAs NFIP Technical Bulletin 6 - Requirements for Dry Floodproofed Below-Grade Parking Areas Under Non- Residential and Mixed-Use Buildings. The entry to the parking garage will be located near the east end of the building, outside of the 100-yr floodplain boundary, and the threshold will be set just above the BFE at 4814.35. The basement parking garage entry will also have a removable water-tight barrier designed to be protective to 2-feet above the BFE. The attached floodplain exhibit shows the locations of these proposed flood protection design elements for the new building. Mechanical/electrical equipment and plumbing fixture installations will follow current building codes and will either be elevated to 2-feet minimum above the BFE in the main part of the building or will be designed per floodproofing standards and/or FEMA/NFIP Technical Bulletin 6 in the lower parking garage levels. Elevator equipment will follow the current building code including applicable ASCE 24 standards for Flood Resistant Design July 19, 2024 PAGE NO. 2 tdhengineering.com and Construction. Gas and electric services will enter the building from the alley to the northeast with connection points and meters located outside of the floodplain boundary. All incoming service equipment will also be located 2-feet minimum above the BFE. A complete plan set for the project is currently being submitted for Site Plan review. It is understood that a Floodplain Development Permit application will need to be submitted and approved prior to final site plan approval, with the subsequent building permit application being required to address the detailed code compliance elements for the building’s mechanical, electrical, and plumbing systems. In the meantime, the attached technical information is intended to demonstrate the project’s floodplain development strategy approach and compliance with the City’s floodplain regulations for this type of project. Please let me know if you have any questions or require additional information. Sincerely, Cody Croskey PE Civil Engineer TD&H ENGINEERING Attachments • Floodplain Regulation Compliance Summary • BFE Calculations • Project Floodplain Exhibit J:\2023\B23-017 32 South Rouse\05_DESIGN (TECH & REPORTS)\FLOODPLAIN\SP FLOODPLAIN NARRATIVE\00 FLOODPLAIN NARRATIVE.DOC BOZEMAN, GREAT FALLS, KALISPELL & SHELBY, MT | SPOKANE, WA | LEWISTON, ID | WATFORD CITY, ND | MEDIA, PA 406.586.0277 tdhengineering.com 234 East Babcock Street Suite 3 Bozeman, MT 59715 MEMORANDUM Date: July 19, 2024 TDH Job No.: B23-017 To: Brian Heaston, PE - City of Bozeman Engineering Department From: Cody Croskey, PE Subject: Canopy Hotel Bozeman Floodplain Regulation Compliance Summary Introduction The following summary is provided to demonstrate project conformance with applicable sections of the City of Bozeman Floodplain Regulations (BMC 38.600) for a new multi-story hotel building with basement parking garage and associated site improvements proposed at the northeast corner of S. Rouse Avenue and E. Babcock Street adjacent to Bozeman Creek. BMC 38.600.180 – Floodplain Permit Application Requirements A floodplain permit application will be submitted as part of the site plan application process that will incorporate all of the applicable information as required by BMC 38.600.180. It is understood that a complete floodplain permit application must be submitted and approved prior to final site plan approval for the project. BMC 38.600.260 – Requirements for Permitted Uses in the Floodway The following items are being addressed for proposed sidewalk and plaza improvements within the Floodway: A. The portion of development proposed in the floodway consists of replacing streetscape elements (i.e., sidewalk and landscape beds) that will meet city and downtown district development standards and be reviewed as part of the Site Plan application process. B. All improvements within the floodway will consist of streetscape improvements intended to match or lower the existing grade while meeting current ADA standards. Therefore, it is not anticipated that the floodplain conveyance capacity will be appreciably altered or restricted in any way. The improvements will consist of permanent hardscape and landscaping that will not dislodge or adversely affect other properties. C. A floodway encroachment analysis will be provided with the floodplain permit application materials demonstrating there is no reduction of the carrying capacity of the floodway. It is anticipated that a simplified no-rise analysis will be acceptable for project given the nature of streetscape replacement as provided in subsection C.1.a of this section. tdhengineering.com PAGE NO. 2 JULY 19, 2024 BMC 38.600.270.D – Requirements for New Buildings Permitted in the Flood Fringe The following items are being addressed for the proposed new non-residential building within the Flood Fringe: 1. The project will follow building codes and be subject to building permit review. 2. The project will be reviewed through the Site Plan application process to confirm consistency with zoning and community growth policy. 3. The main occupiable floors of building will be elevated on a permanent concrete foundation to be 2’ min. above the BFE. The lower basement parking garage levels will be structurally engineered to resist flood forces and will follow FEMA/NFIP Technical Bulletin 6 - Requirements for Dry Floodproofed Below-Grade Parking Areas Under Non-Residential and Mixed-Use Buildings. 4. Surface drainage will be provided with new hardscape and landscaping around the building. 5. Concrete foundation walls and stairs/ramps will be the only exterior building elements exposed at elevations below the flood protection level (2’ above the BFE). Interior occupiable floors and surfaces will be elevated 2’ min. above the BFE. Lower parking garage floors will be dry-floodproofed and constructed using water resistant materials and finishes. 6. The occupiable floors of this non-residential building will be elevated per D.6.a. 7. n/a – no manufactured homes 8. All occupiable floors of the building will be elevated 2’ min above the BFE on a concrete foundation in accordance with subsection D.6.a above. The lower parking levels will be dry-floodproofed and designed in accordance with FEMA/NFIP Technical Bulletin 6. 9. n/a – no appurtenant or accessory buildings 10. n/a – no crawlspaces 11. The basement parking garage will be dry-floodproofed to 2’ min above the BFE per BMC 38.600.270.D.8 and designed in accordance with FEMA/NFIP Technical Bulletin 6. 12. Electrical systems will be designed by a professional engineer to meet building codes including applicable flood hazard area provisions, and the following additional requirements, subject to building permit review. The elevator electrical equipment will also follow the current building code including applicable ASCE 24 standards for Flood Resistant Design and Construction. a. All incoming power service equipment including all transformers, metering equipment, controls, panels, and all other stationary equipment will be located at least 2’ above the BFE. b. Portable and movable electrical equipment may be placed below the base flood elevation, provided that the equipment can be disconnected by a single plug and socket assembly of the submersible type. c. The main power service will enter the building from the alley to the northeast with manually operated electrical disconnect equipment located at an accessible location outside of the flood hazard area. tdhengineering.com PAGE NO. 3 JULY 19, 2024 d. All electrical wiring systems installed below the base flood elevation will be suitable for continuous submergence and may not contain fibrous components. 13. Mechanical systems will be designed by a professional engineer to meet building codes including applicable flood hazard area provisions, and the following additional requirements, subject to building permit review. The elevator mechanical equipment will also follow the current building code including applicable ASCE 24 standards for Flood Resistant Design and Construction. a. Float operated automatic control valves will be installed so that fuel supply is automatically shut off when flood waters reach the floor level where mechanical systems are located. b. Manually operated gate valves will be installed on gas supply lines. The main gas service will enter the building from the alley to the northeast at an accessible location above the BFE and outside of the flood hazard area. c. Electrical components of the HVAC systems will meet the requirements of subsection D.12 above. d. Furnaces, cooling units, and all associated ductwork will be installed at least two feet above the base flood elevation. 14. Plumbing systems will be designed by a professional engineer to meet building codes including applicable flood hazard area provisions, and the following additional requirements, subject to building permit review. a. The new building sewer service will include a backwater valve. b. All toilets, stools, sinks, urinals, vaults, and drains will be located so the lowest point of possible flood water entry is at least two feet above the base flood elevation. J:\2023\B23-017 32 South Rouse\05_DESIGN (Tech & Reports)\FLOODPLAIN\SP FLOODPLAIN NARRATIVE\01 FLOODPLAIN REG COMPLIANCE MEMO.DOC Community Name *BELGRADE, CITY OF Community Number 300105 BOZEMAN, CITY OF 300028 GALLATIN COUNTY UNINCORPORATED AREAS 300027 *MANHATTAN, TOWN OF 300034 THREE FORKS, CITY OF 300029 *WEST YELLOWSTONE, TOWN OF 300135 GALLATIN COUNTY, MONTANA AND INCORPORATED AREAS VOLUME 1 OF 4 Gallatin County *NON-FLOOD PRONE COMMUNITY XXXXXXXXXX xx XXX Federal Emergency Management Agency Flood Insurance Study Number30031CV001B REVISED PRELIMINARY DATE: April XX, 2020 REVISED PRELIMINARY DATE:May XX, 2020 REVISED PRELIMINARY DATE:May 20, 2020 192P193P 74'125.1' BFE = 4814.3 SECTION MEAN WIDTH AREA VELOCITY (FEET) (SQUARE (FEET PER FEET) SECOND)A 245 53 51 5.6 4,802.5 4,802.54,802.80.3B 417 64 54 5.2 4,805.0 4,805.04,805.30.3C 5636053 5.4 4,808.5 4,808.54,808.60.1D 713 53 50 5.6 4,811.8 4,811.84,811.90.1E 983 66 64 5.5 4,813.4 4,813.44,813.60.2F 1,182 64 62 5.7 4,815.3 4,815.34,815.30.0G1,242 65635.7 4,816.1 4,816.14,816.10.0 1Feet above confluence with Bozeman CreekCROSS SECTIONDISTANCE1FLOODING SOURCE FLOODWAYBASE FLOOD WATER SURFACE ELEVATION(FEET NAVD 88)REGULATORYWITHOUT FLOODWAYWITH FLOODWAYINCREASETABLE 8 FEDERAL EMERGENCY MANAGEMENT AGENCY GALLATIN COUNTY, MT AND INCORPORATED AREASFLOODWAY DATAROUSE AVENUE DOWNTOWN114 Map Title City ofBozeman,Montana,Maxar,Microsoft Legend FEMA Floodplain Layers Profile Baselines FIRM Panels Cross Sections Flood Hazard Zones 0.2% Annual Chance Flood Hazard 0.2% Annual Chance Flood Hazard Regulatory Floodway Regulatory Floodway City Limits Parcels Notes This product is for informational purposes and may not havebeen prepared for, or be suitable for legal, engineering, or surveying purposes. Users of this information should review or consult the primary data and information sources to ascertainthe usability of the information. 0 50 100 ftDate: 7/3/2024 Project Location BFE Location REVISIONSHEETB23-017 FLOODPLAIN EXHIBITREV DATE Engineering 234 E. BABCOCK ST., SUITE 3 • BOZEMAN, MONTANA 59715 406.586.0277 • tdhengineering.comDESIGNED BY:QUALITY CHECK:JOB NO.FIELDBOOKDRAWN BY:DATE:.DWGCANOPY HOTEL BOZEMAN BOZEMAN, MONTANA FLOODPLAIN EXHIBIT B23-01707.19.2024CJCBASBASEX-1NOTES