Sixth Ave Culvert Project Walkthrough October 31, 2017

Due to the failure of the 6th Avenue culvert in December 2015, the City contracted for investigation of how to permanently fix the wooden culvert. Through extensive research, it was discovered, that due to regulatory agency requirements, simply replacing the culvert was not as cost-effective as installing a bridge over the stream. Design and permit approvals were obtained last year, but due to regulatory agency requirements, the in-water work window. This timing window restricts in-water work related to activity during certain periods to protect fish from impacts of works in and around water during spawning migrations. The in-water work window has been outlined for October – February.

For the duration of the project (anticipated substantial completion of Feb 15th, 2018) the City has to implement a detour that greatly impacts the local residents, businesses, and school. Many have asked, why is construction of a small bridge going to take so long? The City wanted to maintain southbound traffic along 6th Avenue for the duration of the project. As a result, the construction has been split into two phases so that only one side of the bridge is being worked on at a time. Below is a detailed walkthrough of the entire project that helps to outline this multifaceted process:

Prior to beginning any bridge construction, the following must occur:

  • Installing fish screens to prevent fish from entering stream
  • Coordination with ODFW to remove the fish
  • Locating existing utilities
  • Mobilization of construction equipment
  • Surveying
  • Setting up traffic control
  • Installing piling that will be the main supports for the bridge work
  • Installing erosion control to help prevent construction debris from entering the waterways and stormwater systems
  • Install temporary shoring to help stabilize the road during construction

During Phase 1 and 2 of construction, the following must occur:

  • Excavation
  • Concrete work for the piling
  • Relocation of Sewer Lines both Gravity and Pressure
  • Relocation of all other utilities (water & telecommunication)
  • Sidewalk concrete work
  • Installing precast bridge beams
  • Temporary pavement for traffic flow
  • Install guardrails
  • Install catch basins and storm sewer
  • Install bio swale which treats the runoff and removes contaminants from entering the sewer system
  • Pave permanent asphalt for the road
  • Remove all erosion control and traffic control
  • De-mobilization of construction equipment