Carved in Stone
A Front Range perspective on managing and shipping aggregates.
By Bill Langer
Rocksicle (rok-si-kuhl) noun – similar to a rock glacier, which is a glacier-like mass of rock with interstitial ice.
Not too long ago, I had the opportunity to visit an aggregate operation along the Arkansas River just upstream from Cañon City, Colo. About 85 percent of the material produced at the plant leaves by rail. Although I went to see the geology, I was fascinated by some of the intricacies of how rock is shipped by rail. Besides that, I thought I might catch a glimpse of the dreaded rocksicle.
I joined up with Mike and Terry, who showed me around their operation. The first thing I noticed when we entered the pit were humongous boulders, some almost 10 feet in diameter, strewn all over the place. Terry must have seen my strange expression, because he politely commented that the previous owners of the operation didn’t have a real good handle on what they were doing. It was no surprise to learn that the operation was bought out of bankruptcy in 2003. Which brings me to the following:
Lesson 1: A rail-base operation can fail in good times (early 2000s) if it is not managed well and can survive in bad times (2008 until now) if it is managed well.
Mike pointed out that when his people weren’t working the pit face, they were setting aside some boulders for sale as landscaping material, and breaking and crushing others for use as aggregate. But getting the operation back on track was more difficult than just shoving around boulders. Negative experiences with the previous owners left customers, vendors, permitting and regulatory staff, and local citizen groups extremely skeptical about how the operation would function under the new owners. It had taken years of responsible operations and intense community interactions to regain the confidence of those whose trust had been lost by the previous owners.
Lesson 2: Earning a social license to mine can be a very complicated, time-consuming exercise.
Loading and emptying rail cars is capital intense. Their loadout facility is very simple — a spur (track) to the facility, two front-end loaders, a hopper, a scale, and a conveyor. The cost — $1.25 million, not counting the track. Mike has permits for a new distribution yard in the south Denver metro area, where anticipated demand is expected to require significant imports of aggregate. The cost — $2.5 million, just for the off-loading facility.
Lesson 3: The choice between rail and truck transportation methods involves trade-offs between expenditures of investment capital and operating expenses, flexible systems versus fixed route systems, high-volume shipments versus individual shipments, and transport distances.
I noticed that each car was being loaded with 1 1/2-inch to 3/4-inch crushed rock, prepared specifically for use as ASTM #4A Ballast Rock. The cars can apply ballast directly to the rail bed, thus eliminating the need for an off-loading facility. The ballast was granite, which was the preferred rock for the intended application, and is sufficiently durable that it does not deteriorate during transport. Also, there were sufficient stockpiles to immediately meet the need.
Lesson 4: Transportation management is geared toward providing the customer with the right product, arriving in the right condition, at the right time, at the right place, and at the right price.
We stopped at the plant office just before I left. Terry started to check the forecast temperatures along the route from the operation to their distribution yard in Colorado Springs. I asked, “Why?” The answer: They were shipping washed rock, and if the temperature fell below freezing for too long a time, the wet rock would freeze into a solid lump, and the rail car would remain out of commission until spring.
Lesson 5: Rocksicle.
Bill Langer is a geologist with the Mineral Resources Team of the U.S. Geological Survey and can be reached at 303-236-1249 or via e-mail at firstname.lastname@example.org.