U.S. Sens. Ed Markey, D-Massachusetts, continued to press Columbia Gas executives Thursday for details on what led to a series of gas explosions in Lawrence, Andover and North Andover last month. The senator, who had requested information on the Merrimack Valley gas explosions in a late-September letter, criticized Columbia Gas of Massachusetts — operated by NiSource Inc. — … Continue reading Springfield Republican: US Sen. Ed Markey seeks additional answers on Merrimack Valley gas explosions