In-house hot mix facility saves money for county

McPherson County, Kan., had a 50-ton-per-hour (TPH) asphalt plant in operation for local road maintenance and pothole patching, but in 1991, the plant, which had produced cold mix materials for 20 years, was well past its prime.

By 1993, civil engineer Rodger Young, director of public works for the county, managed to convince the county commissioners that a new asphalt plant would pay for itself in its first year and save millions of dollars over the next several years.

“We had basically run the hell out of the plant at full capacity between 65 TPH and 70 TPH all summer long,” Young says. And, because of torrential rains in 1993 bringing 45 inches (versus the typical 33 inches), a great deal of road work was needed just to stabilize the 324 miles of paved roads under his jurisdiction.

What Young needed in 1994 was a plant that could produce 100,000 tons of asphalt per year.

To receive approval for this expense, Young crunched the numbers comparing the cost of asphalt and past jobs using private contractors and the costs involved in the county’s producing all its own asphalt. “In years past, we made some of our own asphalt and bought some, so I was confident in my numbers,” Young says.

The closest asphalt plant to McPherson County was 35 miles away in Salina. Young figured the cost would average $30 per ton to purchase material and then $5.60 per ton to transport it to a project site.

“With the old plant, we were making asphalt for about $19 per ton, which generated a $16.60 per ton savings,” Young says. “If you subtract $6.60 to cover additional expenses, you still save $10 per ton.”

The plant produced 40,000 tons in 1993, allowing Young to save the county at least $400,000, or enough to pay for a new 160 TPH plant, the foundation and truck scale. He also cited a 1994 project that required 12 miles of stabilization work (5,600 tons) at a contractor price of $479,000 versus his cost of $270,000 to do the complete job with the old plant. “The difference was $49 per ton versus $27 per ton,” he says.

He received approval from the commissioners based on the future need to produce about 100,000 tons of asphalt per year and the fact that the estimated $10 savings per ton alone would save the county about $1 million per year in materials cost.

Young then requested bids from several plant manufacturers for a 160-TPH plant with three cold-feed bins, an 80-ton silo and a scrubber system. “The bids ranged from $300,000 to $800,000 for basically the same plant,” he says. The county then took delivery of a new asphalt drum mix plant in 1994, producing 92,000 tons of hot mix that year.

In 1995, the new plant produced 82,000 tons, and Young expects to produce about 95,000 tons in 1996.

“We’ve got a fiscally conservative county commission that has not increased taxes in McPherson County,” Young says, “but the number of roads in need of major resurfacing has increased.”

Operating a hot-mix plant in the county “affords us the ability to maintain the roadway system to the level desired by the county’s citizens,” he says.

Benefits of the in-house operation include spreading the county’s maintenance dollars in expanded use of the hot in-place recycling process to rehabilitate and lengthen the life of aging county asphalt pavements.

The process, one part of the county’s pavement rehabilitation program, is actually more economical than overlay work, according to Young, because the county can provide the recycling contractor with the HMA.

Additionally, the in-house operation “makes sense for us,” Young says, “since there are very few contractors in the area who can compete for the services that we might consider privatizing. McPherson County has its own engineering staff and designs most of its bridges. It has its own materials lab and does its own project inspection and construction management,” he says.