Deep in the heart of Texas sits what seems to be one of the Lone Star state’s richest lignite deposits. According to the Texas State Historical Society, “a thorough survey on which to base an accurate estimate of Texas coal and lignite resources has never been made, but it is estimated that there are 60,000 square miles of lignite territory with a supply of probably 20 billion tons of commercially valuable lignite.”

For three decades the people who operate the Calvert Mine have extracted a sizeable share of that supply. Located in Bremond, about two hours northeast of Austin and almost halfway between the Dallas/Fort Worth Metroplex and Houston, the mine’s permit covers approximately 8,300 acres. Each year, mining operations uncover and move roughly 2 million tons.

Operations Manager James Johnson describes the lignite as a lower-grade coal than found in other locations around the country. “It’s younger and softer than what you would get in the Powder River Basin in the northwest, for example, or the bituminous seams in Illinois and Pennsylvania. The fact that we have been here for 30 years shows that despite its properties, it’s still a very valuable commodity.”

Operations began in 1989, and the mine developed simultaneously with a power station that is located on an adjacent property. One hundred percent of the lignite harvested each year at Calvert Mine goes to that plant, which generates and distributes power to nearly 250,000 residential, commercial, industrial, and other customers.

“Our target is a 6,600 to 6,800 BTU (British Thermal Unit) product that the plant uses to generate power for the grid,” said Mine Manager Jason Buenemann. “We mine three seams, and the lignite in them varies. In two of the seams, the BTUs are typically in the 5,500 to 5,700 range with an ash content of 16 to 20 percent. The third seam is generally between 7,000 and 7,400 BTUs with 10 to 14 percent ash. As we extract, the materials are stockpiled and then blended in order to achieve the power plant’s targeted BTUs with 16 to 18 percent ash.”

Lignite seam depths also vary greatly throughout the mine. The shallowest is close to 60 feet deep from the highest point of the topography to the bottom of a seam floor, while the deepest right now runs approximately 230 feet. Each year, the mine opens around 250 acres of land for new extraction, while concurrently reclaiming the same amount.

“As we uncover one cut, we’re simultaneously backfilling the previous one,” Buenemann pointed out. “The first step in getting to the lignite is clearing and grubbing trees and brush, followed by removing and salvaging topsoil. We are one of only a few mines that separates the topsoil from other dirt, and our goal is direct placement of it during reclamation.”

After topsoil stripping, overburden removal begins. Dirt is placed and dozed in reclamation areas to predetermined post-mining topography, with slope aspects and proper drainage in mind. Topsoil is then spread out, followed by seeding. The Texas Mining and Reclamation Association has recognized Calvert Mine with a Special Project Reclamation Award for its efforts.

Moving mass amounts of materials with high production and efficiency requires large equipment. In 2008, Calvert Mine purchased its first Komatsu machine, a 200-ton-plus PC2000 that initially performed overburden stripping and has since been converted to a lignite-extraction unit. The mine purchased the excavator with the assistance of WPI, which also helped with a conversion from an 18-yard rock bucket to a 24-yard coal bucket.

“All along we intended for it to eventually replace an older shovel at the coal face,” said Mine Maintenance Manager Gilbert Speelman. “The larger bucket didn’t slow it down at all; in fact, our production numbers went up. The PC2000 proved to be a perfect match for our trucks. It was a big win for us.”

Calvert Mine personnel consider the addition of the world’s first Komatsu Tier 4 Final PC4000-11 to its fleet another triumph. Komatsu introduced the 400-ton mining shovel at the 2016 MINExpo.

“It was moved from the Vegas show floor to the mine,” said Buenemann. “We were initially looking for another PC2000, and our timeline was to bring a new machine onboard in 2020. In the meantime, we were considering rebuilding what was really an antiquated competitive-brand shovel. Komatsu, Komatsu Financial, and WPI talked with us about a plan to acquire the PC4000 right away, maintain our financial flexibility and drop the rebuild. This gave us immediate availability of a new, larger machine. It proved to be a game-changer.”

WPI personnel assembled the machine on-site and changed out the original ground-engaging tools to ones more conducive to the mine’s materials. Komatsu and WPI teamed up to provide operator training, as well as to educate the mine’s maintenance personnel on preventive practices.

“If we have any concerns, WPI is right there to help, whether by phone or on-site,” said Mechanic Wendell Johnson. “WPI gives us added value with its vendor-managed inventory system. That involved setting up a parts-consignment warehouse at the mine and charging us only when an item is pulled from the inventory. That’s especially useful and a big time-saver if we are in the middle of a shift, so we don’t have to call for a technician to come out or wait to have a part shipped to us.”

Calvert Mine put the PC4000-11 into production in March 2017 and utilizes it for overburden removal. Operators can load 150-ton trucks in four passes with dirt from a 30-foot face.

“Its performance is excellent in that situation,” shared Johnson. “With the shovel configuration, our operators can take a much thicker lift. It has great breakout force and gives us fast cycle times. Our production numbers are outstanding, and moving forward those factors will come into play even more. Our strip ratio is expected to go up, so the PC4000 will be assigned to moving even more material.”

Close to the same time as when Calvert Mine put the PC4000-11 into action, it asked WPI to complete a major rebuild of the PC2000, which recently passed the 25,000-hour mark. Some of the rebuild tasks were performed at WPI’s Houston branch shop, while others were done on-site at the mine.

In addition to the PC4000 and PC2000, Calvert Mine owns Komatsu water trucks as well as a PC360LC excavator, which is used for clearing and grubbing. It also rents dozers and other equipment as needed from WPI. Purchases and rentals are handled with the help of WPI’s Director of Major Accounts Frank Pagura and Major Accounts Representative Tim Nice.

“Komatsu’s Firm Future Order program provided some guaranteed pricing as we developed our budget and planned for the rebuild with WPI,” stated Speelman. “Service really stands out to us; and Komatsu, WPI, Frank and Tim have been outstanding in that regard. Every quarter we meet to address any topics that need attention and make sure we are on the same page. We are very happy with the relationships that have been built.”

“That extends to Komatsu Mining,” added Buenemann. “The recent acquisition of Joy Global strengthened the Komatsu brand on our site. Komatsu Mining is the primary support for our dragline. It takes care of major outages, manufactures parts and does welding and non-destructive testing for us. Without Komatsu Mining’s support for the dragline, our downtime would be significantly higher.”

In an era when many coal and lignite operations have closed or are now shuttering operations with the rise of renewable energy and natural gas, Calvert Mine continues to thrive. Buenemann credits a focus on implementing solid practices and a staff of close to 100 employees who are willing to do whatever it takes to make the mine successful.

“Our team is cross-functional,” said Buenemann. “Operators perform preventive maintenance, and mechanics will run equipment, if needed. That team atmosphere keeps us competitive and is essential to a 24-hour-a-day operation.”

That teamwork will remain vital to Calvert Mine’s future. We have permitted reserves that will last through 2030, and we are actively looking for additional reserves to extend that further,” said Buenemann. “Right now, we’re also planning for maximizing production as our strip ratios increase. That may involve larger trucks that are a better match for the PC4000. It is something we will proactively address going forward.”