Ten percent of Maryland's gas mains are cast or wrought iron, higher than all but four other states and D.C., according to the federal agency. (States that urbanized earlier are more likely to have old pipes.)
Though the Maryland surcharge bills were criticized as a utility "bailout" by some liberal Democrats and conservative Republicans in the General Assembly, the proposals easily passed both chambers. Supporters worry that people living near old gas mains are at risk.
The 30 "significant incidents" involving gas pipelines in Maryland from 2002 to 2011 killed one person, injured 16 and caused $12 million in property damage, the Maryland Department of Legislative Services reported in its analysis of the surcharge bills.
But the agency, which didn't note whether deterioration caused those incidents, added that surcharges could be said to shift financial risk from the companies to the customers because the flow of money starts sooner — and because a utility could have less incentive to rein in expenses.
The head of the Maryland Office of People's Counsel, which represents residential utility customers, said both she and the National Association of State Utility Consumer Advocates oppose infrastructure surcharges.
"From our perspective, this is not a safety issue," said Paula M. Carmody, the Maryland people's counsel. "Everybody agrees the companies [must] maintain a safe and reliable system. The disagreement between the consumers and the utilities has been over how do they collect the revenues."
One of the problems with surcharges, Carmody said, is that they separate a single type of expense from all the rest. In a rate case, a utility's intertwining expenses and the money it made are all looked at together.
AARP's Bresnahan said utilities don't like rate cases in part because they have to cough up so much information.
"I truly believe they're trying to get out of the whole rate process, and this is the beginning of that," she said of the surcharge measure.