Colonial Pipeline Co. will pay the largest civil penalty ever to the U.S. Environmental Protection Agency for violations of the Clean Water Act, the government agency reported earlier in the week. Under a settlement agreement, the Atlanta-based firm, which transports refined petroleum products through an underground pipeline that stretches from Texas to New York, will upgrade environmental protection on that pipeline at an estimated cost of $30 million and pay a $34 million civil penalty. The penalty, the largest paid in EPA history, will go the Oil Spill Liability Trust Fund, which underwrites nationwide oil spill cleanup activities. The EPA said Colonial Pipeline violated the Clean Water Act when pipeline corrosion, mechanical damage and operator error led to the release of some 1.45 million gallons of oil and other petroleum products into the environment. That included a nearly 1 million gallon spill of diesel fuel into a S. Carolina river in 1996.