Rocks keep Latrobe rolling

As the home of Rolling Rock Beer, thousands of “rocks” leave Latrobe, Pa., every day. But last winter, Dave Williams, superintendent of public works, needed the crushed rock that makes up his antiskid to stay put. Liquid calcium chloride allowed him to do just that.

A fierce storm hit the region with near blizzard conditions in january, bringing 24 inches of snow, 25-mile-per-hour winds and temperatures down to minus 23 degrees Fahrenheit. Little moved on the roads of this town of 10,000 located 40 miles east of Pittsburgh. And to make matters worse, Williams was running dangerously low on road salt.

“I had a good amount heading into that 36-hour storm, but the task of keeping our roads open demanded so much that our stockpile was nearly depleted well before the storm ended,” says Williams. “The entire region went into crisis. Nearby towns were paralyzed, businesses were shut down and what vehicles could move were slipping and sliding. I could not accept that the same would happen to Latrobe.”

The roads serve not only the brewery but two local steel mills and several high-tech firms. Moreover, Latrobe is under contract to maintain the section of Highway 981 that runs through it. With no options left, Williams decided to use the liquid calcium chloride he sprays on salt to prewet antiskid. This was a first for his department and a crucial decision that kept his roads open.

Williams applied the same amount of calcium chloride to the antiskid as he did to salt — five gallons per ton of antiskid. The spreaders on the trucks were calibrated to lay down 800 pounds of the wet abrasive per lane mile, as opposed to the 500 pound setting used for salt. The goal was to create a heavy blanket of antiskid, which contains one-quarter- to three-eighth-inch chips of crushed limestone, so tires would always be in contact with at least one stone chip.

Four two-man crews worked around the clock in 12-hour shifts spreading the antiskid. Normally it takes less than two-and-a-half hours to treat the 35 miles of road, but in the extreme conditions of the storm complete coverage took nearly eight hours as the crews battled abandoned cars, snarled traffic and equipment breakdowns. In the end, three antiskid applications were made during the blizzard.

“The difference was striking,” says Williams. “Roads outside the borough line had 6 inches of hard-packed snow and ice, but those in Latrobe were clear.”

Williams found that when liquid calcium chloride coats the rock chips in antiskid, they embed in packed snow and ice. They stay in tire tracks where they are needed unlike uncoated chips that can be scattered off the road by traffic.

Williams has used pre-wetted salt for two winters. He first gave it a try after attending a conference during which public works directors from Allegheny County sang the praises of liquid calcium chloride, noting that it works in sub-zero temperatures, well below the level at which salt alone becomes ineffective.

Latrobe’s calcium chloride operation involves a drive-under spray bar fed by a 10,000-gallon tank. Once the 32-percent calcium chloride solution made by General Chemicals, Parsippany, N.J., is sprayed on salt or antiskid, it quickly penetrates the entire load.

“It’s a good thing we have liquid calcium chloride on hand to fight the storms we have had,” Williams says. “I now know I can use the liquid on salt and antiskid, which gives us a tremendous advantage. When other local road systems are shut down, ours are still open.”