John Pappas, of Eckles Construction, gives a presentation Wednesday evening, Jan. 3, on the progress of the Knoch High School renovation. William Pitts/Butler Eagle

SAXONBURG — The renovation of Knoch High School, which began last month, has run into some unexpected roadblocks which may drive up the price by tens of thousands of dollars. One of those roadblocks is the discovery of slag underneath the construction site.

John Pappas, of Eckles Construction, one of the firms advising the Knoch School District on the renovation project, explained the situation at the school board meeting on Wednesday evening, Jan. 3. According to Pappas, the construction crew on the site recently discovered slag under the student parking lot, where the high school is currently building an addition.

Slag is a waste byproduct from the process of smelting. According to Pappas, the slag found under the school parking lot has a tendency to expand when exposed to moisture, which could cause problems for the project down the line if not addressed.

“We don't see this a ton, but when we do, the first thing we do is get it checked,” Pappas said. “There’s two types of slag. One type can be expansive, and the other type you don't have to worry about. We had it tested, and I can tell you it is expansive.”

Pappas strongly recommended the school district have the slag removed so future parking lots on the site would not succumb to expansion and cracking, and so footers for the foundation for the school addition will have a solid base on which to rest.

“They need to remove that and fill that with something else, so that the future parking lots won't crack, and so that the foundation footers can be poured for the addition,” said district superintendent David Foley.

Another problem came up over winter break, when crews discovered that the school’s underground power lines were in the way of the planned location of footers for the foundation of the high school extension.

“We need to put a footer in a certain place, and that power line with concrete is located going across that area,” Foley said. “They have to figure out a way to drop in new footings around that concrete.”

Removing the slag and moving the storm lines will more than likely drive up the cost of the project. Pappas estimated the price tag would go up by $42,000.

“In order for the project to succeed, it has to be taken care of,” Foley said.

One silver lining is that the underground slag pile didn’t reach far below the parking lot.

“Luckily it was not at foundation level, or even fill material level,” Pappas said. “That would have been a lot more material to have to remove. But it’s still a good amount of material.”

John Pappas, of Eckles Construction, gives a presentation on the progress of the Knoch High School renovation on Wednesday evening, Jan. 3. William Pitts/Butler Eagle