Just around the corner from their Branford High School (BHS) classroom, Matt Park's Advanced Placement (AP) environmental science students received a textbook tour of environmental cleanup in action at the former Atlantic Wire mill.

"I think it's an incredible opportunity. It's one thing to talk about it in class, but to truly get in here and see how actual remediation being done is another. They're really lucky to have this chance to see a real-life example that's right in Branford," said Park.

Not many have had the chance to step inside the imposing mill site, which shut down several years ago.

The Feb. 3 tour was arranged by realtor Greg Robbins of Greg Robbins & Associates, with permission from property owner One Church St., LLC. The class got a bit of a history lesson from Bill Hitchcock, grandson of Atlantic Wire founder William Hitchcock; and learned about recent clean-up efforts at the site from environmental scientist Paul Muniz of Environmental Partners.

Muniz, the site's clean-up consultant for nearly a year, shared firsthand knowledge about types of contamination found and the cost-effective physical and chemical remediation methods used to clean it up.

Bill Hitchcock once worked at the mill founded by his grandfather in 1906. He described the process of milling steel rods into wire that could be drawn down to the thinness of a paper clip before it was spooled and sent off for use. The rolled steel rods delivered to Atlantic Wire for milling first had to be cleaned of naturally occurring iron oxide (rust) as well "mill scale" iron oxide, Hitchcock said.

"Almost everything that came in was put in sulfuric acid, which would react with the iron oxide. The iron content in the sulfuric acid would get higher and higher and then we'd reclaim it in the tower to cool it," said Hitchcock, of the mill's 1970s through early 2000s cleaning process.

The resulting crystalized iron sulfate would be removed from the tower "and that's how we handled the pollution," Hitchcock said.

However, in the years before the 1970s Clean Water Act (CWA), mills and factories didn't have many restrictions on handling pollutants, Muniz explained.

"They used chemicals and, as with many factories, this one happens to be on a river, which was a place to get rid of waste products," Muniz said.

After the CWA, factories were allowed to bury waste in holes in the ground or build a part of the factory to treat the waste and then take it away, as was the case at Atlantic Wire. The company also used lime (calcium oxide) or borax (sodium borate) to coat wire to give it certain properties, such as making wire either neutral or a "carrier," as Hitchcock termed it. Solvents used to clean processed wire of materials such as burnt lubricant included a gasoline-based concoction with additives.

Muniz said recent remediation of residual contaminants in the soil included digging and removing dirt, including a yard of dirt under floors once holding huge cleaning machines. Not too long ago, a chemical cleaning process was also used to clear some soil containing solvents, in ground beneath the mill's many overspill floor wells.

"A couple of years ago, there were pump tankers in the yard brewing up peroxide, which was injected into the wells, and that got the solvents in the soil to a better level," Muniz said.

Once upon a time, a huge locomotive steam engine powered the mill, but it was removed long ago; said Hitchcock, who used to delight in watching it run when he was a kid. It was replaced by an oil-fired boiler fed by an underground tank. Over time, oil spilled or otherwise touching the ground around the tank area leached downhill into soil beneath the mill's central "courtyard." Oil gathered underground over decades, creating one of the major environmental cleanup issues recently tackled on the site in the past months, Muniz told the students.

"Twelve feet below the ground, they had a big puddle of oil. We dug out the tank and removed it; and dug a 20-foot deep hole to remove all of the mucky, oily soil," which was then sent off to be turned into asphalt, he explained.

BHS Senior Madison Birney said she was getting a lot of information out of the visit.

"It's interesting to see how they actually are taking things from the classroom and putting it use," she said.

Robbins took the time to share with the class some of his vision for what the former mill could become with a mixed use of the property and said he wanted the kids to know the history of Atlantic Wire in Branford and the potential for this site. The mill is situated on 8.5 acres and has 200,000 square feet of space in its buildings.

"This was a sophisticated operation which supported hundreds of families," said Robbins. "I want them to know what Atlantic Wire was to Branford, and why Paul Muniz is helping us to clean it up, so it can be something again, [which] depends on how clean we can get the property and what happens in town."

Muniz told The Sound he specializes in consultation work to clean up brownfields such as Atlantic Wire and has found no contamination surprises here. The work is nearing completion.

"The surprise is how clean it is," Muniz said.

Touring third floor of the building, BHS Senior Jess Carlson and her classmates took in unique views of the Blackstone Library. Built on the peak of a rise in Main Street, the library and its copper dome are perfectly framed in the mill's tall windows. Other views include huge swaths of the Branford River.

"It's really pretty. It's cool to see what it was years ago, and what they're doing now, and how it will develop," said Carlson.