City of Astoria – CSO Phase 4 – 16th Street Separation Project

The 16th St CSO Project in Astoria was a street reconstruction project with the intent to separate the storm and sewer system while upgrading the street along the way. The project was located on the south side of Hwy 30 up towards the Astoria Column on 13-14% grade roads. The project consisted of the removal of 2,100 SY of walk and driveway, 65 each catch basins, and 3 each manholes. A 200 LF slip-lining of 24-inch diameter HDPE through existing 30-inch sewer was performed which required the use of a 16” reversible pneumatic hammer. Prior to the slip-lining 3 each 40’ deep and 1 each 30’ deep groundwater control wells at 24” diameter were installed as this area was anticipated to have a lot of groundwater. We installed new storm drainage mainline on each street for 8,935 LF of 12” PVC. There were 55 each 48” manholes and 2 each 60” manholes installed with the storm drainage mainline. Each intersection also had new catch basins for a total of 90 each and 8” PVC inlet leads at 3,400 LF. There was a small amount of sewer improvements consisting of 635 LF of 12” PVC, and 630 LF of 6” PVC laterals. The project also required the installation of waterlines varying from 4” to 14” Ductile Iron for 1,980 LF and 2” to 12” Gate Vales for 22 each. There was 2 each fire hydrant assemblies and 1 each 14” Butterfly Valves installed. Due to lack of surveying provided on the job, the new ADA ramps became a design/build. We constructed 6,200 SF of ADA ramps, 1,000 SY of sidewalk, 410 SY of driveway, and 4,900 LF of curbs. The final major construction item was 22,650 SY of 16” street reconstructs inclusive of 4” of asphalt paving for 5,300 tons over 12” of 1” minus on subgrade geotextile.

Owner: City of Astoria

Engineer: Gibbs & Olson

Location: Astoria, Oregon

Completion Date: 2016