The Shaw Group Inc. said Tuesday that it has finished installation of equipment that can cut emissions of sulfur dioxide by up to 98 percent from three coal-fired power plants in Maryland.

As part of the deal with Mirant Mid-Atlantic LLC and Mirant Chalk Point LLC, Shaw installed four flue gas desulfurization systems on seven units at the plants. The contract was worth $1.1 billion.

Shaw also provided engineering services on one unit for a system capable of cutting nitrogen oxide emissions by up to 90 percent at one unit.