Project Status and Schedule

As of November 8, 2019

LiDAR (Light Detecting and Ranging) Survey: The LiDAR survey was completed June 2015 using a helicopter flight. Property control and river cross section surveys, within legal rights-of way, were also conducted at that time. To date, surveys are completed in all areas where legal property access is available.

Geotechnical Drilling: Geotechnical drilling of two boring holes within legal rights-of-way was completed August 2015. Additional geotechnical borings are planned prior to completion of the final design.

Cultural Resource Survey: The cultural resources services for this project included a Class III Cultural Resources Survey to consider the potential effects upon previously recorded archeological and historic sites as well as identify previously unidentified resources present within the project area in accordance with Section 106 of the National Historic Preservation Act (NHPA) of 1966 (as amended in 2006) and other applicable federal historic preservation legislation and regulations. The cultural resource inventory was completed February 2016.

Environmental Documentation: Environmental technical studies were completed as part of the environmental documentation for the project. The South Avenue Bridge Project includes a Categorical Exclusion environmental document and Section 4(f) Evaluation consistent with FHWA guidance on Environmental Impact and Related Procedures, as described in 23 CFR 771.117. The Categorical Exclusion (CE(d)) environmental document includes an analysis of a full range of environmental, social, and economic resources, including evidence of compliance with other environmental directives, as applicable.

  • Detailed Noise Analysis Report: Completed November 2016.
  • Biological Resource Report and Preliminary Biological Assessment: Completed January 2017.
  • Biological Assessment: Completed September 2018.
Roadway Design: The Preliminary Roadway & Traffic Report was completed in November 2016. The report included roadway design criteria, preliminary traffic and safety features, intersection geometrics, and roadway design recommendations.

Bridge Design: Multiple bridge types and span configurations were evaluated for the project and summarized in the Bridge TS&L (Type, Size, and Location) report, which includes recommendation for the preferred bridge alternate. Conceptual options to rehabilitate and/or preserve the existing Maclay Bridge were evaluated as part of the environmental review process and included preliminary structure design and layout of approaching roadways and planning-level cost estimates.

  • Bridge Type, Size, and Location Report: Completed October 2016.
  • Maclay Bridge Preservation Options Analysis: Completed January 2019.

Hydraulics & Hydrology:

  • The existing FEMA hydraulic analysis of the reach was reviewed and the results and proposed methods of the future analyses were discussed with the County, FEMA, and MT Dept. of Natural Resources and Conservation (DNRC).
  • The preliminary hydraulic analysis report was drafted and submitted to the County and MDT detailing the reviewed alternatives and their corresponding effects on the floodplain elevations and scour. The entities have approved of the analysis.
  • The Floodplain Administrator requested a numerical analysis on O’Brien Creek to ensure that the proposed alternative will not adversely affect surrounding structures or increase the existing 1%-annual-chance flood elevation more than 0.5’.
  • Due to the necessary realignment of River Pines Road, HDR analyzed the local irrigation structure under River Pines Road to determine if it needs to be extended or replaced.
  • A Conditional Letter of Map Revision (CLOMR) for Missoula County detailing the proposed conditions of the project along the Bitterroot River is being developed.