Salafia said selectmen will discuss the possibility of calling a Special Town Meeting on Monday night.
Deso said other options include stopping construction until the details are worked out or reconfigure the design of the school. Both would have negative effects including further increased cost and not having enough room to fit all the students, he said.
At the meeting, Deso noted other towns in the state are facing similar problems.
A debt-exclusion override to pay for the new school was approved by residents in January 2011 after voters overwhelmingly supported the project at Special Town Meeting the month before.
While the total cost of the building is $44.7 million, the state will reimburse the town $16.8 million of that cost, lowering Andover’s share to about $27.9 million.
The new two- and three-story school is expected to hold 680 students. The building will replace the current wood-frame school built in 1969, which has well-documented structural problems.
The two neighbors appealed the Conservation Commission’s decision to approve the project in September 2011, claiming there would be adverse effects to their properties. The town ended up settling with the two neighbors in April.
If all goes to the plan the school will open in the fall of 2014, Deso said.