Armstrong Construction of Kingsport will undertake the project for a fee of just more than $5.9 million.
Tim Shaw of Shaw and Shanks Architects said commission approval means the notice to proceed to the contractor could come as early as next week.
"The timeline is slated for occupancy in the summer of 2008," Shaw said.
The winning bid was nearly $1 million lower than the next lowest bid, $6.8 million, from J.A. Fielden contractors of Knoxville and came in close to the architects' estimate of $5.81 million for the project.
With nearly $50 million coming to city schools from a Washington County bond issue for school facility construction, some commissioners questioned whether all or a portion of $10 million already dedicated to the project from a city bond issue and school board capital improvement funds might be better spent elsewhere.
To that end, Mayor Steve Darden directed City Manager Pete Peterson to examine possible other uses for those funds.
The project's first phase, which would renovate and expand the 8-9 campus's central building, has core offices, computer labs and classes that must be relocated within the Science Hill complex this summer before students return in the fall.
The majority of functions from the central building would move to the eighth-grade and ninth-grade buildings, although some, such as band, would move to the 10-12 campus where the necessary facilities are located. So some students would have to travel between campuses, posing scheduling concerns.
Some commissioners wondered if potential project delays might force reopening of the building to January 2009.
"I would say we move in when it's ready," Director of Schools Richard Bales said. "We have several breaks built into the school year now, so there are more opportunities."
Remaining phases in the project would renovate the 8-9 campus's two other classroom buildings, erect a gymnasium and cafeteria at the 8-9 campus, and add a ninth-grade wing to Science Hill's 10-12 campus. Bales estimated costs for renovating the two remaining classroom buildings at $12 million to $14 million.
Armstrong Construction also built Lakeridge Elementary School and has performed other work for the school system in the past.