Downtown Ennis Pedestrian Bridge Feasibility Report Town of Ennis December 2018 Prepared by: Madison County ® DOWNTOWN ENNIS PEDESTRIAN BRIDGE FEASIBILITY REPORT MADISON COUNTY December 2018 Prepared for: Town of Ennis Prepared by: Great West Engineering, Inc. 2501 Belt View Dr. Helena, MT 59 TOWN OF ENNIS | Downtown Ennis Pedestrian Bridge – Feasibility Report Table of Contents 1.0 Project Identification ......................................................................... 1 1.1 Project Location ............................................................................................................... 1 1.2 Physical Characteristics of the Area ............................................................................... 2 1.3 Project Objective .............................................................................................................. 2 2.0 Site Location Analysis ........................................................................ 3 2.1 Alignment 1 – Modify Existing MDT Bridge ................................................................... 4 2.1.1 Land Ownership ....................................................................................................... 4 2.1.2 Access/Infrastructure Development ....................................................................... 4 2.2 Alignment 2 – 140 feet downstream of Highway 287 Bridge ...................................... 5 2.2.1 Land Ownership ....................................................................................................... 5 2.2.2 Access/Infrastructure Development ....................................................................... 5 2.2.3 Other Impacts ........................................................................................................... 5 2.3 Alignment 3 – 530 feet downstream of Highway 287 Bridge ...................................... 6 2.3.1 Land Ownership ....................................................................................................... 6 2.3.2 Access/Infrastructure Development ....................................................................... 6 2.4 Alignment 4 – Old Highway Alignment ........................................................................... 7 2.4.1 Land Ownership ....................................................................................................... 8 2.4.2 Access/Infrastructure Development ....................................................................... 8 2.4.3 Other Impacts ........................................................................................................... 8 2.5 Selection Criteria ............................................................................................................. 9 2.6 Basis of Selection for Preferred Alignment Alternative ............................................... 10 3.0 Pedestrian Bridge Alternatives ....................................................... 11 3.1 Alternative A – Relocation of Varney Bridge ................................................................ 11 3.1.1 History and Significance of the Existing Bridge ................................................... 11 3.1.2 Existing Bridge Configuration ................................................................................ 12 3.1.3 Present Condition................................................................................................... 13 3.1.4 Safety Considerations ............................................................................................ 15 3.1.5 Asbestos & Paint .................................................................................................... 15 3.1.6 Bridge Configuration .............................................................................................. 16 3.1.7 Useful Life ............................................................................................................... 17 3.1.8 Construction Duration ............................................................................................ 17 3.1.9 Cost Estimate ......................................................................................................... 17 TOWN OF ENNIS | Downtown Ennis Pedestrian Bridge – Feasibility Report i 3.2 Alternative B - New Single-Span Pedestrian Bridge .................................................... 19 3.2.1 Bridge Configuration .............................................................................................. 19 3.2.2 Safety Considerations ............................................................................................ 20 3.2.3 Useful Life ............................................................................................................... 20 3.2.4 Construction Duration ............................................................................................ 20 3.2.5 Cost Estimate ......................................................................................................... 20 3.3 Alternative C - Retrofit Existing MDT Highway 287 Bridge ......................................... 22 4.0 Alternatives Analysis ........................................................................ 23 4.1 Selection Criteria ........................................................................................................... 23 4.2 Cost Comparison ........................................................................................................... 23 4.3 Basis of Selection for Preferred Alignment Alternative ............................................... 24 5.0 Preferred Alternative ........................................................................ 25 5.1 Preferred Alternative Discussion .................................................................................. 25 6.0 Background & Design Information .................................................. 26 6.1 Geotechnical Considerations ........................................................................................ 26 6.2 Hydraulic Discussion ..................................................................................................... 26 6.3 Access Road & Work Bridge Construction ................................................................... 26 6.4 Wetlands ........................................................................................................................ 26 6.5 Hydrology ....................................................................................................................... 27 6.6 Floodplains .................................................................................................................... 27 6.7 Utilities ........................................................................................................................... 30 6.8 Agricultural & Forest Lands .......................................................................................... 30 6.9 Biological Resources ..................................................................................................... 30 6.10 River Corridor Use ...................................................................................................... 32 7.0 Project Implementation .................................................................... 33 7.1 Overall Approach ........................................................................................................... 33 7.2 Project Implementation Tasks ...................................................................................... 33 7.2.1 Grant Administration .............................................................................................. 33 7.2.2 Design Phase ......................................................................................................... 33 7.2.3 Contracting Phase .................................................................................................. 33 7.2.4 Construction Phase ................................................................................................ 34 7.2.5 Project Closeout Phase .......................................................................................... 34 7.3 Necessary Permits, Regulatory Approvals and Easements ........................................ 35 7.4 Applicable Statutes, Rules, Regulations, & Standards ............................................... 35 TOWN OF ENNIS | Downtown Ennis Pedestrian Bridge – Feasibility Report ii List of Figures Figure 1: Location Map of Lions Park ........................................................................................... 1 Figure 2: View of the Lions Park trail ............................................................................................ 1 Figure 3: Site Map and Bridge Location Alternatives .................................................................. 3 Figure 4: View along Highway 287 Bridge looking southeast along Alignment 1. .................... 4 Figure 5: View looking from Lions Park southeast along Alignment 2. ...................................... 5 Figure 6: View looking from Lions Park southeast along Alignment 3 ....................................... 6 Figure 7: View looking southeast along Alignment 4. .................................................................. 7 Figure 8: View of the original Jeffers Bridge installed in 1897. (Photo courtesy of Jon Axline, MDT) ................................................................................................................................................ 8 Figure 9: Location