The City of Coos Bay does municipal construction projects to maintain and improve the city and better serve residents.

In December 2016, the City broke ground for an expansion and upgrade to the existing Wastewater Treatment Plant No. 2, located in Empire at S Empire Boulevard and Fulton Avenue. This project replaces and upgrades the current treatment plant, providing better water quality and is able to meet future needs of the community. The plant was officially opened on October 3, 2018 with a formal ribbon cutting ceremony.


Tonight Patchy Fog - 56ºF

Tuesday Patchy Fog then Partly Sunny - 66ºF

Tuesday Night Mostly Cloudy then Patchy Fog - 54ºF

Wednesday Patchy Fog then Mostly Sunny - 68ºF

Wednesday Night Partly Cloudy - 52ºF


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Construction impacts, including detours and expected delays

No traffic impacts are expected at this time. 

The limits of the WWTP2 project will include 490 Fulton Avenue, Fulton Avenue west of S. Empire Blvd, and Fulton Avenue between S. Empire Blvd and Marple Street.

Trucks and equipment will enter the plant site from S. Empire Blvd and from Marple Street. They will exit onto Fulton Avenue and Marple Street. The roads adjacent to the plant site will be open to traffic at all times, but there may be brief delays with flaggers while equipment enters or leaves the site. Pedestrian access will be closed or limited on the east side of S. Empire Blvd.

Fulton Avenue west of S. Empire Blvd will be heavily traveled by equipment and trucks.


Wastewater Treatment Plant No. 2 Expansion and Upgrade

WWTP2 Panorama

The City of Coos Bay is constructing an expansion and upgrade to the existing Wastewater Treatment Plant No. 2. Plant 2 treats sewage for western Coos Bay, including Empire, Barview, and Charleston. The existing plant is over 50 years old and will be upgraded with current technology, new Sequencing Batch Reactor treatment basins, and UV disinfection. The plant will provide better water quality and the ability to meet current and anticipated DEQ standards for the future needs of the community. The new facility is built at 490 Fulton Avenue, just north of the Lighthouse Market. The plant is designed with capacity for population growth for a minimum of 20 years. It will be built so that modules may be added as needed for future expansion.

M.A. Mortenson Construction and their local construction partners, Billeter Marine and Kyle Electric, built the upgrades. CH2M in partnership with the local engineering firm SHN Engineers & Geologists Inc. designed the new plant.

A 1% interest DEQ State Revolving Fund wastewater loan with a $500,000 grant is funding the project. The total cost of the construction improvements is budgeted at $24,531,820.

The project started in September 2016 and completed in late summer 2018. Piping connecting the outfall to the new plant site was installed in the fall of 2016 during the road project to reduce traffic delays for residents.


Project Schedule and Current Status


Photos showing progress of the construction

SBR with clean water
9/7/18: SBR filled with clean water

8/20/18: Overview of site

7/31/18: Clean water in basins

6/12/18: HVAC system in Control Building

5/15/18: Sequencing Batch Reactor (SBR) Tank

5/5/18: Overview

5/2/18: West side of SBR

4/24/18: Overview of site

4/16/18: Sitework

4/9/18: East Side of SBR

3/27/18: Installation of diffusers on bottom of SBR

3/27/18: Headworks

3/14/18: Overview of Site

2/27/18: Influent Pump Station

2/23/18: Electrical/Shop Building

2/21/18: Overview of Site

1/2/18: Overview of site

1/2/18: Stairs will provide access for Operators.

Miles of electrical conduit are installed throughout the project site

12/26/17: Trusses in place for the Operations Building

12/20/17: Overview of Site

12/5/17: Installation of air diffusers along bottom of SBR Tanks

12/4/17: Operations Building

12/1/17: Headworks

11/30/17: Overview of Site

11/30/17: Plant Piping

11/30/17: Installation of Grit Removal System in Headworks

11/13/17: Overview of Site

10/31/17: Headworks & SBR Tanks

10/24/17: Overview of Site

10/6/17: Top view of SBR Tanks

10/3/17: Overview of Site

7/28/17: Overview of site

7/27/17: Watertight testing for the East Tank

7/12/17: Overview of site

6/30/17: A wall divides the East & West SBR Tanks

6/30/17: Filling Equalization Basin with clean water for Watertight Testing

6/29/17: Overview of site

6/27/17: Looking into the East tank

6/17/17: The headworks starting to take shape

6/15/17: The West tank is halfway complete

6/1/17: Setting the rebar for the concrete tanks

6/1/17: Overview of site

5/23/17: Overview of site

5/17/17: Headworks Wall

5/15/17: Headworks going vertical

5/5/17: Overview of the site

4/17/17: Slab foundation for the headworks.

4/7/17: Wall installation and concrete work.

3/30/17: Pouring concrete and installing rebar for the walls.

3/23/17: Installing more rebar for the walls.

3/17/17: Installing reinforcement rebar for the walls

3/14/17: Beginning to tie rebar

3/9/17: Over excavating and replacing with rock and fabric

3/1/17: Both SBR basins excavated. Both SBR basins have been excavated. The geotechnical report had indicated that there was prior fill covering an un-named creek that once crossed the site. Once the fill was removed, the contour of the old water way was visible. The backfill is stabilization rock with geotextile wrapped around it, then layers of crushed rock with geogrid between the layers. The large rock is on the left side of the photo and the crushed rock on the right.  A roll of geogrid is at the bottom of the photo. With all components in place, the basins will have a firm foundation to rest on.

2/22/17: East SBR basin. The east SBR basin has been excavated. The backfill with rock has started to provide support under the concrete basin.

2/14/17: Baker Tank. The excavations are kept dry by pumping the water to a “Baker Tank”. Baffles in the tank settle out solids so that the water discharged to the storm drains is clean.

2/6/17: SBR Excavation.  Excavation continues on the east SBR basin

2/8/17: Sequencing Batch Reactor basin.  View to the west from Marple Street up above the construction. This is the big basin dug for the Sequencing Batch Reactor. The brown object is a tree trunk that was dug up during excavation. Most of the basin has been dug down to undisturbed soils, but there is some old fill on the site that still needs to be removed.

2/8/17: Sequencing Batch Reactor basin. View to the east from Empire Blvd. This shows how deep the basins are. The white is filter fabric to help hold the bank during construction. There has been a lot of rain this week and the site is pretty muddy, but the contractor has begun to put rock into the excavated basins to form the foundation support. The rock will reduce the mud and make it easier to work.

1/31/17: SBR Basin Soils. The Engineer, Geologist, and Contractors examine the bottom soils of the east SBR basin.


Staff leading the WWTP2 project.

The City has invested considerable effort into securing a team of engineers and contractors with extensive experience in wastewater projects. There are quality control procedures and levels of inspections to check at every step of the way. As with all construction projects, there are a lot of moving parts and pieces to make the job site function properly. Our team is there to ensure that each part is done correctly and safely for the plant to be constructed properly. While their experience is in different fields of construction, together they have formed a great team. They are passionate about their work and the successful completion of this project.

Jan Kerbo

Jan Kerbo, PE, Resident Project Representative

Jan is the representative for the City for the WWTP2 project.

541-269-1181 ext. 2206

Bob_Sanguinetti Bob Sanguinetti, Project Manager for Mortenson Construction

Bob serves as Mortenson’s onsite representative in managing the construction of the project from all levels (safety, schedule, budget, and quality) and acts in the interest of the City of Coos Bay as their Construction Manager.


Current city projects

Wastewater Treatment Plant No. 2 Expansion and Upgrade

Empire Boulevard


Projects that will be starting soon

Eastside Safe Routes to School 

The City, Coos Bay School District, and Oregon Department of Transportation (ODOT) partnered on a Safe Routes to School project to provide safer pedestrian access to and from Millicoma School. The project location extends from Millicoma School (2nd Ave.) to the Isthmus Slough Bridge. The project improvements include storm infrastructure, sidewalks, accessibility ramps, marked crosswalks, and rapid flash beacons. The City applied for and was awarded a $2 million Safe Routes to Schools grant from ODOT to partially fund the project. The project schedule is still currently being worked out with the contractor, but is expected to begin in April 2020.

4th Street Pedestrian Safety Improvements

Construction of the 4th Street Pedestrian Safety Improvement Project (Phase I) is also expected to begin in April 2020, which includes reconstruction of the roadway, new traffic lights, bumpouts, new pedestrian crossings including rapid flash beacons, and ADA compliant sidewalks. The project location is within the Coos Bay Urban Renewal District and extends from Commercial Avenue to Donnelly Avenue. The City has partnered with the Coos Bay North Bend Water Board for the replacement of a water main in the same area. The City intends to complete similar improvements to 4th Street from Market Avenue to Commercial Avenue and Donnelly to Elrod at a later date (Phase 2).