East High School is sporting a scar about 4 feet wide and 8 to 10 feet deep, stretching along the entire south side of the school grounds.
But school district officials hope testing conducted in the trench Wednesday will give them conclusive evidence of any seismic faults running near or through the school and help them decide what safety measures are needed to prevent deaths in the event of an earthquake.Stu Murchison, consulting staff geologist for the firm of Sergent Hauskins and Beckwith, said earlier land borings to predict ground stability in an earthquake proved inconclusive and trenching was necessary. Similar studies conducted at West and Highland high schools conclusively showed no liquefaction problems.
"We don't anticipate there are any faults, but we want to make sure," Murchison said.
After the trench is dug, Murchison said, he takes soil samples from the varve sediment layers to test for linear ruptures or shifts in the layers. He said faults occur in those layers.
In the all-day process, Murchison logs the layers in the trenches above and below a measured baseline. He can make a fair judgment of any seismic activity in the area at that time, he said.
But the consultants will also do an in-depth geometric analysis from the collected data and soil samples to positively identify any offsets in the layers.
Bruce Ririe, manager of operations for Salt Lake City School District, said preliminary findings of this study will be presented to the board at its next meeting on June 19. Depending on the results, Ririe said, the board will make recommendations for the high school at the end of the year.
The geotechnical studies conducted at the three district high schools are a result of a massive study released in December saying the school district needed to spend $50 million to $80 million on its schools to make them safer in case of an earthquake. The study reported an estimated 1,706 to 2,922 students would be killed district-wide if a an earthquake measuring 6.2 on the Richter scale occurred during school hours. And East was ranked third of the three high schools for safety in an earthquake.
"We wanted the information (from the trenching) to give us further guidance and background to work with in deciding the fate of East High School," Ririe said.
Because the high schools have the largest concentration of students, studies were conducted there first. Jan Keller, Salt Lake City School District staff coordiantor, said tests at the district's five intermediate schools will be conducted after the high school tests are assessed.
Ririe did not know the total cost of the three borings and trenching, but earlier estimates were set at $27,100 to $34,200.