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Under-River Crossing Structure

May contain: water, nature, outdoors, stream, river, and creek

In 1973, a new concrete under river crossing structure was built to accommodate 24” and 20” pipelines. The 24” pipeline became the new plant influent line and the 20” pipeline was used as a conduit for the 14” recycled water distribution line. Both of these lines are active today.

In July 2010 the Monterey Peninsula Water Management District alerted the District to the declining sediment level in the river which had exposed our structure. The top of the structure is now approximately 2 feet above the river bottom on the downstream side and approximately level with the river bottom on the upstream side. The concern is not only that the structure may become an impediment to fish migration, but also, whether the exposed structure is now subject to forces that may damage the structure. In addition to the hydraulic forces acting on it, there is potential for large debris coming downstream striking the structure and causing damage.

The District Board approved a contract with Cornerstone Structural Engineering in December 2010 to evaluate the structure itself and also the potential consequences of hydraulic scour and seismic activity.