The project: Seismic rehabilitation of the River Mill Elementary School to ensure life safety and structural integrity in the event of a major seismic event.

The goal: Estacada School District aimed to strengthen the River Mill Elementary School facility, one of only two elementary schools in the District, to better protect students, staff, and community members during seismic events. The school was also designated to serve as an emergency shelter for the region and needed to meet Immediate Occupancy standards outlined in ASCE 41-17.

Project amenities: The River Mill Elementary School spans 40,500-sf and includes classrooms, offices, a cafeteria, and an auditorium. Originally constructed in 1968 and remodeled in 2002, the building is framed with gypsum-sheathed wood walls and a mixed wood roof system.

Design approach: IMEG led the design team and collaborated closely with the District and the CM/GC to ensure the rehabilitation was executed effectively within the awarded grant budget. The design team carefully developed seismic strengthening solutions that minimized disruptions to the school’s operations and expedited construction timelines. Seismic measures included the addition of plywood shear walls throughout the facility, long glulam wood collectors, metal strapping, and holdowns. To accommodate the building’s varied roof elevations—specifically, the higher cafeteria space and lower classroom wings—discontinuous shear walls were used in combination with horizontal collectors and holdowns to effectively distribute lateral forces.

Due to budget constraints, replacing the roof diaphragm was not feasible, so strengthening occurred entirely from below. Despite these limitations, our team strategically addressed multiple long-standing maintenance issues alongside the seismic improvements, including repairing a sagging entry soffit and replacing interior lighting and ceiling grids.

Project outcome: Completed during the school’s short summer break, the project was delivered in full before the return of students in the fall. The upgraded building now meets Immediate Occupancy standards and serves not only as a daily learning environment but also as a designated emergency shelter for the community. The project reinforced the school’s vital role in Estacada, supporting both education and regional emergency preparedness, while staying within the constraints of Oregon’s Seismic Rehabilitation Grant Program award.