This project is the first new ocean outfall design in Oregon in over 23 years, and will replace the City’s noncompliant effluent discharge to Agate Beach. The project has required extensive archeological, geotechnical, and environmental investigations that concluded the design will provide no significant impacts to the natural environment.

SHN and its team of specialized consultants conducted onshore and offshore geotechnical evaluations, archeological investigations and excavations in a native American village site, botanical and wetland mitigations, near-shore oceanographic surveys, current metering studies, a mixing zone analysis for the Pacific Ocean, and an assessment of the impacts to the marine biological community. This information was used to coordinate with and address the concerns of environmental agencies, the environmental community, Native Americans, the Army Corps of Engineers, and most importantly the concerned citizens of Port Orford.

Improvements included construction of an effluent disposal pipeline, ocean outfall, and diffuser system for the discharge of treated effluent to a disposal point 2,250 feet offshore. Construction of the outfall used horizontal directional drilling to install the pipe through 10,000-psi rock beyond the surf zone to waters at a depth of 7 fathoms where the outfall diffuser structure has been anchored to a hard but irregular rocky bottom.

Additional improvements include an upgrade to the wastewater treatment plant including retrofitting an existing extended-air treatment facility, providing unit process redundancy, installation of UV disinfection equipment, an effluent pumping station, new influent pump station, new clarifier, RAS pumping equipment, and DO control systems. In addition, collection system improvements employing pipeline rehabilitation and remove and replacement methods of construction were performed to remove infiltration and inflow and reduce peak flows by 15%.

Return to Civil Projects