The Pennsylvania Public Utility Commission on Wednesday voted to investigate a Columbia Gas of Pennsylvania proposal that calls for a 10 percent increase to the average monthly bill of a residential customer.

Columbia Gas has requested to increase base rates by $54.1 million per year. For the residential customer who uses 72 therms of gas per month, the bill would increase from $87.12 to $96.20.

That request is suspended for up to seven months and will be assigned to the Office of Administrative Law Judge for public hearings and a recommended decision or settlement. That is part of the PUC's standard process when considering a rate increase, and the commission must issue a final decision by Dec. 20.

Columbia Gas asked for the rate increase to pay for upgrades to its aging infrastructure, said company spokeswoman Rachel Ford.

From 2007 to 2013, the company invested more than $700 million to modernize and expand its distribution system throughout the state. Of that amount, more than $540 million was dedicated to replacing nearly 570 miles of aging pipe.

This year, Columbia Gas will spend $145 million on upgrades throughout the 26 Pennsylvania counties where it provides natural gas service.

Previous rate hike: The company asked for a 16 percent rate increase last year, adding $11 to the average bill, and the PUC approved it.

This year, in addition to the recently proposed rate increase, the PUC is also investigating the natural gas provider's plan to implement a new pilot rider program.

The program would spread out costs to new natural gas customers.

Instead of paying all the costs of connecting to the service up front, it would be paid over 20 years through a monthly surcharge not exceeding $35.

Those costs vary due to a number of factors, including the distance to an existing main line, the size of pipe needed to provide new service and the number of customers who would be part of a line extension, Ford said.

Columbia Gas serves about 417,000 customers across the state and 101,438 of those customers are in York County, she said.

— Reach Candy Woodall at cwoodall@yorkdispatch.com.