It’s a scary thought, but a severe earthquake could occur at any time in the Puget Sound region. It has been 300 years since the last time that the area was struck by a subduction zone earthquake. Subduction is the process where one tectonic plate moves under another tectonic plate, sinking into the earth’s mantle, as the plates converge.

Engineer Jim Collins, with PCS Structural Solutions of Seattle, was tasked to evaluate Islander Middle School, all three elementary schools and the North Mercer properties for structural integrity in the event of an earthquake.

Island Park Elementary, Islander Middle School, Lakeridge Elementary and West Mercer Elementary were all remodeled in 1995, but the North Mercer buildings have not undergone a structural upgrade in over 50 years. Collins said it is unknown how well the walls are reinforced in the North Mercer buildings, and they are the only buildings with concrete roofs.

“Changes to code are inevitable, but these North Mercer buildings were built to 1958 code,” Collins said.

The old North Mercer campus buildings are susceptible to collapse in an earthquake, but the other buildings were upgraded for seismic strength during the remodeling.

In a MCE (maximum considered earthquake) seismic event, IMS and the three elementary schools wouldn’t collapse — the kids would get out, Collins concluded, but the buildings would be damaged beyond repair.

This study is just one more issue to be grappled with as the Mercer Island School District board of directors decides how to frame a bond issue to be placed before voters, perhaps as soon as April 2012.

Superintendent Gary Plano pointed out that since all the schools were remodeled at the same time, there would be no backup facility if indeed all the schools were damaged beyond repair.

The engineering report said the buildings, excluding the North Mercer campus, could survive another earthquake due to the 1995 remodeling. However, IMS and the elementary schools would be unsafe for students to return.

Dean Mack, the executive director of business services for the district, presented the cost per square foot for new schools, based on criteria proposed by the 21st Century FPC. Not taking in inflation, and including “soft costs” such as furnishings, fixtures, playground equipment, permitting, etc., new elementary schools would cost $400 to $425 per square foot, with classrooms for 650 students and common space for 725 kids. Each school would cost $30 to $34 million.

A new middle school with classroom space for 1,100 students and common space for 1,200, would cost $394 to $421 per square foot — more cost efficient because of size, Mack said.

There are variables as well, such as whether to build the structures to serve as emergency shelters, have science labs, and preschool/day care. A new middle school would cost about $67 to $75 million.

The final conundrum that the board discussed is building in place, vs. demolition and utilizing a “swing” school to house students while their particular school is being built. Island Park would most likely be set on a different area on its site. Since the new school would have two stories, it makes sense to move the footprint since the site is sloped, whereas the design could be similar to a daylight basement.

Plano said a consultant who looked at the site said Island Park and Lakeridge are currently not on the optimal spot on their sites, which would make them good candidates for building on site while students are still in the old school. But it also sounded like the board is still toying with the idea of a fourth elementary school, if a site could be found on the Island.

“Let’s put the buildings on the best location on the sites if we can,” said Frank Morrison of the 21st Century Facilities Planning Committee. He said parking, access and fields need to be factored in, too.

Carrie George, who was also on the 21st CFPC, made a case to the board for urgency, hoping they move quickly so as to get a bond on the April ballot. To do so, the district would have to file by March 2. Mack said voter support decreases by 15 percent if the bond is put off until the August primary or November general election.

Board president Pat Braman said the board hopes to reach out to the public in February. Sixty percent voter approval is needed for a bond to pass.

Discussion on facilities will continue at the Dec. 15 regular board meeting.