As the German-owned Lehigh Cement Co. prepares for growth at its Union Bridge plant, company officials hope to gain permission soon from Carroll County commissioners to permanently store an alternative fuel source and to expand mining at a higher-quality limestone quarry in nearby New Windsor.
The county commissioners said they are close to approving an amendment allowing Lehigh to continue storing treated sewage sludge on its grounds. Lehigh officials said theirs is the first cement plant in North America to burn the pelletized sludge, known as biosolids, as an alternative fuel to power the plant's cement kiln.
The commissioners, who planned a public hearing Tuesday on the biosolids issue, toured the Union Bridge plant Wednesday. Plant manager Kent Martin briefed the commissioners on Lehigh's desire to gain mining permits so it can quarry limestone from a 700-acre parcel that the company owns, south of New Windsor.
Commissioner Michael D. Zimmer complimented the "long-range thinking of the company and the strong emphasis on the environment."
"They've spent a tremendous amount of money watching their operations and how it affects their neighbors," Zimmer said.
After years of dirty emissions, air quality at the cement manufacturing plant has improved, county environmental leaders have said.
Lehigh obtained permits and a temporary zoning amendment to begin test-burning the sanitized sludge in early 2006 - a process that has been closely monitored at the state and county level. In September, county commissioners renewed Lehigh's yearlong permit to store up to 400 tons of dried biosolids in a 130-foot silo built for that purpose on the plant's grounds.
In July, the Carroll County Environmental Advisory Council approved Lehigh's request to store the biosolids. Council members noted Lehigh's efforts to use a renewable resource as fuel. No solid waste is produced by the biosolids because the ash is used in clinker, a powdered cement product.
The plant fires six tons of biosolids per hour in its kiln, Martin said. But coal still makes up 85 percent to 90 percent of the fuel source to produce optimal conditions, Martin said.
County Attorney Kimberly A. Millender said the commissioners are expected to grant Lehigh indefinite permission to store the biosolids by mid-September.
Lehigh also has a goal to extensively mine limestone from the New Windsor quarry - a plan in the works for more than 10 years that still needs county approval, Martin said.
Grinding limestone at a rate of 8,000 tons a day, the plant will exhaust its current Union Bridge quarry within 10 years, Martin added. Lehigh presently holds a permit to mine only 66 acres of the 700-acre New Windsor tract. But with new mining technology, it is more efficient to evenly quarry rock from the entire parcel, Lehigh environmental engineer Kurt Deery said.
"But we're not in a position yet to bring stone from New Windsor to Union Bridge," Deery added.
Limestone is blasted and removed from part of the New Windsor site on almost a daily basis, Martin said. But the rock won't be crushed there until the plant gains approval to mine the entire parcel, he said. Plant officials also have to figure out how to transport the limestone about four miles to Union Bridge. Options include trucking it in, expanding cargo railroad lines or building a conveyor belt system, Martin and Deery said.
"At this point, we're looking at all the options," Deery said.
Limestone from the New Windsor quarry is considered higher grade. It's unusually white because of its low iron content, Deery said.
Blending the higher-quality limestone with that from the Union Bridge quarry would stretch out the plant's reserves, Martin said.
Within five years, Lehigh hopes to be mining the entire New Windsor quarry site, Martin said. Meanwhile, crews are preparing the 700-acre site, stripping the clay soil in preparation for quarrying.
Mining only 66 acres of the quarry now would make it more difficult later to extract the limestone from the rest of the site, Martin said. Plant officials could still face opposition from New Windsor residents. When Lehigh first applied for a state permit to install a 400-ton-per-hour rock crusher at the New Windsor site almost three years ago, a once-dormant residents' group revived to challenge that effort.
In the past, residents had concerns that rock-blasting sessions would create dust and increased traffic from the quarry, Deery said.
Pumping water out of the quarry could also drain water from New Windsor area wells, said Dan Strickler, chairman of the New Windsor Community Action Project.
Lehigh has lately been more responsive to residents' concerns, Strickler said.
"They've been very cooperative," he said.