Location

Portland, OR

Start Date

28-6-2016 1:30 PM

DOI

doi:10.15142/T3380628160853

Description

The mouth of the Columbia River (MCR), located at the river’s confluence with the Pacific Ocean between Oregon and Washington, is a critical regional and national gateway for trade and commerce. The MCR is protected and stabilized by three rubble-mound jetties, all of which are in need of major rehabilitation. In 2014 rehabilitation starting with construction of the North Jetty Lagoon Fill project.

Soon after construction of the North Jetty in 1917, deposition of sand caused the formation of a wide beach along the north side of the jetty, which helped protect much of the north side of the jetty from ocean erosion. However, over time, a linear ‘lagoon’ feature formed adjacent to the north side of the jetty, primarily caused by erosion and piping through the jetty. This erosion was accelerated by the presence of a small stream that connected with the lagoon and drained through the jetty structure. The erosion was jeopardizing the foundation of the jetty and contributing to ongoing jetty deterioration.

Simply filling the lagoon would not have been a long term solution without addressing the causes of the erosion. Of the design elements included, three were key; (1) construction of a rock filter adjacent to the jetty, (2) construction of an erosion protection structure near the west end of the lagoon area, and (3) construction of a weir structure to allow stream drainage through the jetty. Construction was completed in June 2015

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Jun 28th, 1:30 PM

Mouth of the Columbia River North Jetty Erosion Stabilization

Portland, OR

The mouth of the Columbia River (MCR), located at the river’s confluence with the Pacific Ocean between Oregon and Washington, is a critical regional and national gateway for trade and commerce. The MCR is protected and stabilized by three rubble-mound jetties, all of which are in need of major rehabilitation. In 2014 rehabilitation starting with construction of the North Jetty Lagoon Fill project.

Soon after construction of the North Jetty in 1917, deposition of sand caused the formation of a wide beach along the north side of the jetty, which helped protect much of the north side of the jetty from ocean erosion. However, over time, a linear ‘lagoon’ feature formed adjacent to the north side of the jetty, primarily caused by erosion and piping through the jetty. This erosion was accelerated by the presence of a small stream that connected with the lagoon and drained through the jetty structure. The erosion was jeopardizing the foundation of the jetty and contributing to ongoing jetty deterioration.

Simply filling the lagoon would not have been a long term solution without addressing the causes of the erosion. Of the design elements included, three were key; (1) construction of a rock filter adjacent to the jetty, (2) construction of an erosion protection structure near the west end of the lagoon area, and (3) construction of a weir structure to allow stream drainage through the jetty. Construction was completed in June 2015