The state Public Utilities Commission said Tuesday the violations stem from construction work performed by the natural gas company and subcontractors beginning in 2013.
Commissioner Carlisle McLean says that the commission's investigation "may have prompted" Summit Natural Gas to take a hard look at its management and contracting practices.
Chairman Mark Vannoy notes that Summit overhauled its quality assurance processes, oversight of subcontractors and internal company training and construction manual.
The company also hired a new CEO, Kurt Adams, in 2015.
In a statement, Adams says the company has strengthened pipeline safety standards and will focus on providing "safe, reliable and clean-burning natural gas."