The 27-inch televisions are piled in the hallway of the new Harper Park Middle School in Potomac Station. The terrazzo tile is still being cemented near the main gymnasium. Furniture is being unpacked, and teachers slip in and out as they move their stuff into classrooms.

Even the road to the new campus is a work in progress. Potomac Station Drive is a flat mass of black tar on one side, gravel on the other, tractors lined up. Surveying the unfinished scene, one of Loudoun County's most powerful school officials pronounces that it will be done on time.

He is Mark X. Burke, director of construction for Virginia's fastest-growing school district and the third-fastest in the nation. His job: to make sure that the assembly line of new campuses is completed on time and within budget.

In Loudoun, where some schools are at their enrollment capacity a few years after they open, delays and cost overruns would have consequences not only on education but also on politics. Any problems could jeopardize voter support for what has become an annual bond referendum for campus construction.

Building schools is a daunting challenge for a school construction manager in any city or town. But Burke is juggling more than just a few projects. Loudoun is in the middle of an unprecedented building boom that calls for 26 more schools in the next six years.

"This never stops," he said. "It's the nature of my beast."

When pressed, he concedes that he occasionally feels weighed down by his responsibilities--"until I think of the Personnel Department, and then I know some folks have a tougher job than I do," he said. By the time school starts late this month, the district will have hired about 400 teachers to accommodate the spiraling growth.

Burke said his immediate concerns are the four new campuses and three elementary school additions that must be ready Aug. 30, when Loudoun schools reopen with a record 28,884 students.

Besides Harper Park, three new elementary schools will open: Cedar Lane in Ashburn, Horizon in Cascades and a new campus in Round Hill. New additions will expand Waterford Elementary and Catoctin Elementary.

These days, Burke spends a lot of time touring the new schools, searching for unfinished corners and missing equipment and inspecting the work of hundreds of trades people.

Under the district's tight schedule, 18 months are alloted to build a school, Burke said. That gives him four months after the voters approve the project to prepare bid specifications; two more months for the Loudoun County School Board to receive, review and award a contractor's bid; and 12 months for site grading and construction, which Burke oversees.

If he gets rattled by the relentlessness of the process, he doesn't show it.

To prod workers who try to convince him that the time line is too short, Burke said he tells them that the Empire State Building was built in 16 months.

He, in turn, is nudged by top school administrators, whose reputations rise and fall, in part, on how the school district's rapid growth is managed. "My superintendent gently reminds me, 'Mr. Burke, school doesn't open in October,' " Burke said.

Superintendent Edgar B. Hatrick III laughed at that quote and said he may have said it once. But he admitted that he has implied it many times more.

He said Burke's strength is his mastery of every facet of school construction, which allows the district to keep to its building schedule.

"In the world of construction, you can't fake it. You have to know what you're doing," Hatrick said. "If you don't have that overall knowledge, there are a lot of ways that you can be done in. [Burke] has that sixth sense not only for what is going right, but what could be wrong."

Burke, 47, was born in Jersey City, and his family moved to Fairfax County when he was a boy. At Colorado State University, he studied to be a national parks superintendent but wound up working at engineering firms instead--on residential, commercial and industrial construction projects, but never a school. That's what led him to Loudoun nine years ago, when he joined the school system's Support Services Department. In 1995, he was named director of construction.

Relaxing to Burke means going back to Colorado to hunt elk. Frankly, he likes to hunt anywhere--and he looks the part, like someone who just stepped out of an L.L. Bean catalogue.

He built his own house long before he came to Loudoun--a 1,700-square-foot saltbox on 12 1/2 acres--where he lives with his wife, Susan, and their daughters, ages 12 and 16, as well as three horses and three Siberian huskies.

As head of Loudoun school construction, Burke has been on the front lines of the debate between elected officials on the School Board and the Board of Supervisors about building costs.

He recently accompanied Hatrick and other school officials on a tour of school buildings in Douglas County, Colo., the second-fastest-growing school district in the nation, where new campuses have been built more cheaply than in Loudoun. The group will discuss its trip at a School Board meeting this fall, probably in September.

Meanwhile, Burke cautions that using inferior materials to reduce construction expenses, as some officials have advocated, may cost more money in the long run.

"What you have to look at is the life cycle of the building," he said. "You want to incorporate materials that are able to maintain that life cycle, maintain that appearance and still provide functionality."

Burke said he looks constantly for ways to improve the design of the new schools and prepare them for an onslaught of students. At Cedar Lane, for example, the teacher's lunchroom could be converted to a classroom at any time: It already has computer hookups.

He said he wakes up in the middle of the night sometimes, thinking about one detail in one contract for one school. He will leap out of bed and write down his thought so he doesn't forget it. He knows it's all part of the job.

"Welcome to my nightmare," he said.