Hydrographic Surveying

City of Eureka/Greater Eureka Area Sewer Outfall

Client: City of Eureka
Funding Source: City of Eureka
Project Location: Humboldt Bay - Eureka, CA

The City of Eureka sewage treatment facility disposes of treated effluent via a subsurface pipeline into Humboldt Bay.  In 1995, large winter storms damaged the armored protection of the pipeline and exposed the pipeline to future damage and potential failure.  Pacific Affiliates was hired by the City of Eureka to commission immediate repairs, to monitor pipeline coverage and provide alternative coverage options. 

Immediate initial repairs saved the pipeline and prevented further damage.  Continued monitoring has showed a cyclical trend in subsurface sediment movement as a result of wave and tidal movement.  Although sediment movement has produced periods of more than desired exposure for the pipeline, continues monitoring has prevented the loss of use of this essential utility.

Pacific Affiliates continues to monitor the sewage outfall pipeline with annual hydrographic surveys and subsurface diver investigation.

Tasks Performed:

  • Hydrographic Surveys
  • Geotechnical Investigation
  • Alternative Armoring Techniques and Analysis
  • Subsurface Investigation (Camera and Diver Investigation)
  • Annual Monitoring and Reporting