Domtar Corp. will spend about $25 million to convert boilers to natural gas from coal and modernize equipment at two paper plants in Pennsylvania. The work will allow the company to retain about 430 jobs in the Johnsonburg paper plant and another nearby paper-converting facility. The Pa. Commonwealth Financing Authority approved a $1 million grant for a $4 million project to install a three-mile natural gas pipeline to the paper plant. Domtar also gets $75,000 from Pennsylvania for working training. Domtar agreed to also spend $12 million over the coming three years to improve processes, machine controls and efficiency at the Johnsonburg plant. Another $9 million will improve a Domtar paper-converting facility in DuBois, Pa., about 50 miles from Johnsonburg.