DESCRIPTION: The Netarts-Oceanside Sanitary District (NOSD) recently completed a new wastewater treatment plant in Oceanside, Oregon. The ±10-acre site is located adjacent to logging roads, ±1 mile south of Cape Mears Loop Road. The new facility includes shop and office buildings, a SBR structure and associated pavements within the northern portion of the property. Two new sludge lagoons were built within the southern portion of the site. Effluent is pumped to and from the new plant via a new pump station built at the original treatment facility along the oceanfront, and then discharged into the ocean via an outfall structure.
SERVICE: Foundation Engineering completed a geotechnical investigation for the project. Our scope of work included a site-specific seismic hazard study, deep exploratory boreholes, installation and monitoring of inclinometers to evaluate potential deep-seated slope movement or creep, laboratory testing, engineering analysis, and recommendations for site preparation and foundation design and construction. We also provided on-site consultation during the earthwork, and foundation construction for the new shop, offices and SBR structures. Construction challenges included the presence of fractured rock in one of the lagoon excavations (which required treatment prior to installation of the membrane lining), construction of deep fills and slopes, and disposal of large quantities of excess spoils.