Engineers say some damage at Epping school was caused by earthquake
In a draft report prepared by SFC Engineering Partnership Inc. of Auburn, engineers who inspected the building shortly after the 4.0 quake on Oct. 16 said the building "was already in a vulnerable state for an earthquake of the magnitude recently experienced to cause the damage observed. That vulnerability became evident as the general framing layout and specific design features of the renovated timber structure were revealed."
Watson Academy housed the town's recreation center until last month when it was closed so the damage could be assessed. The recreation center has been forced to relocate as town officials decide whether to propose repairs to the building that could carry a price tag of between $100,000 and $500,000.
The damage outlined in the engineering report included cracked drywall and wall panels on both floors; door trim separation resulting in at least three doors that are now difficult to close because the door frames have dropped and separated from the door trim; sloping floors; overstressed and fractured wood floor framing; and problems with roof trusses.
Some of the cracks in the drywall and wall panels appear to have existed for some time while others were more recent, the report said. Most of the cracks were found on the second floor.
Nearly every floor on both levels of Watson Academy is sloping toward the center of the building, the report said.
In addition, the report said, "there are signs of stress fractures in the wood joists and beams occurring throughout the basement. . It is likely that the joists were already quite damaged and overstressed for some time prior to the seismic event."
The report said poorly placed shims supporting severely damaged joists at the center portion of the building in the boiler room were key to the damage found on the upper floor.
"The layout of the building shows that the center wall was creating an unintended load path to the joists that were compromised by the placement of the shims. The earthquake likely got the cross wall on the upper floor to rock back and forth. With no continuous hold downs to keep each end from lifting, the wall may have been slammed up and down as the earthquake got the building to rock," the report said.
The rocking of the bell tower and the heavy bell above the roof level is also believed to have contributed to the bowing of wood panels and the shifting of door frames.
While selectmen are awaiting a final report with additional findings and repair options, the engineering firm made some preliminary recommendations. The draft report said the central floor joists of the first floor framing are damaged beyond repair. New floor framing would be needed and the beams that support the joists must be strengthened, the report said.
The firm also suggested installing a new carrying beam in the basement.