Black Hills Corp.has asked Arkansas regulators for permission to recover in rates its recent investments in safety, reliability and system integrity. Since 2016, Rapid City, SD-based Black Hills has invested more than $160 million in replacing, upgrading and maintaining more than 5,500 miles of transmission and distribution lines in the state. If approved by the Arkansas Public Service Commission, gas utility revenues will increase by an estimated $29.9 million annually, and the utility's return on equity will be set at 10.2%. Black Hills expanded to Arkansas in 2015 when it acquired SourceGas Holding LLC for $1.89 billion, more than doubling its utility operations in eight states.