The City of Stayton completed an $11M expansion of its wastewater treatment facility located at the south end of Jeffers Way. Priority I improvements requiring geotechnical input included a new maintenance building, a filter addition, and a new selector cell. The new maintenance building was ±3,000 SF, pre‑engineered metal structure. The filter addition will have a footprint of ±480 SF and will be constructed at grade. A new ±3,040 SF selector cell, at-grade structure was also constructed. An existing gravel service road around the sludge basin at the south end of the site will be extended and paved.
Our scope of work included field exploration, monitoring ground water levels, laboratory testing, engineering analyses and recommendations for site preparation and foundation design and construction. A seismic hazard study was also completed for the facility improvements. The project was completed on schedule and within budget. Foundation Engineering also provided on-site consultation during construction.
One of the geotechnical challenges was the reuse of an abandoned effluent lagoon for construction of the new sludge dryer and storage facility. The abandoned lagoon contained extremely soft sediments that had to be removed and replaced with granular fill under saturated conditions. Foundation Engineering was present during the mitigation work.