Democratic lawmakers in New England have proposed federal legislation designed to increase pipeline safety in the wake of a deadly series of natural gas explosion and fires in suburban Boston last year.

The Leonel Rondon Pipeline Safety Act calls for the Department of Transportation (DOT) to require natural gas pipeline operators create more robust integrity management plans. The new rules would, among other things, require a greater focus on the presence of leak-prone cast iron pipes and on risks that could result in operation above the maximum allowable operating pressure. It also directs operators to avoid using a risk rating of zero for low-probability events.

Leonel Rondon died during a series of explosions that rocked the Merrimack Valley in Massachusetts last September. At least two dozen people also were injured and 131 structures were damaged. A preliminary investigation by the National Transportation Safety Board said the explosions may have been caused by gaps in construction work orders on a cast-iron, low-pressure system built in the early 1900s and operated by Columbia Gas of Massachusetts, a subsidiary of NiSource Inc.

The proposed legislation would require operators to submit copies of their distribution integrity management plans, emergency response plans, as well as procedural operations and maintenance manuals to the DOT's Pipeline and Hazardous Materials Safety Board or to state regulators. The bill calls for DOT to require operators implement best safety practices, or a pipeline safety management system, according to recommendations by the American Petroleum Institute.

The bill also calls for a professional engineer to approve important changes to a pipeline system, and that a qualified gas employee be on-site at a district regulator station to monitor gas pressure during construction work.

Civil penalties would be substantially higher. Operators that run afoul of pipeline safety standards would face a maximum penalty of $20 million for each violation, up from $200,000 currently. The maximum penalty limit would also be increased to $200 million from the current limit of $2 million.

Sen. Ed Markey of Massachusetts said the bill is designed "to ensure that no natural gas company is allowed to shortchange safety ever again. Without strengthening safety regulations, America's natural gas pipeline infrastructure remains a ticking time bomb."

The Senate version of the bill is sponsored by Markey and Sens. Elizabeth Warren of Massachusetts and Richard Blumenthal of Connecticut. Rep. Lori Trahan of Massachusetts is sponsoring companion legislation in the House.