Virginia regulators have accused the builder of the Mountain Valley Pipeline of environmental violations punishable by fines and repair mandates, saying the company’s failure to install and maintain erosion-control devices has fouled 8,800 feet of streams in six locations.The Virginia Department of Environmental Quality gave Robert Cooper, project manager for EQT Corp. in Pittsburgh, a nine-page notice of violations on Monday. The energy company, which hopes to fill the line with natural gas by the end of the year and is permitted to continue working, has 10 days to respond.Five months into tree-clearing, grading and digging needed to bury the pipe, the $3 billion project faces possible state enforcement action for the first time. West Virginia previously notified EQT of alleged violations on that state’s portion of the pipeline.