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Natural gas pipeline safety in Ohio

The PUCO is committed to ensuring the safe, reliable and environmentally sound operation of Ohio's natural gas pipeline system. PUCO investigators inspect each natural gas pipeline system in the state at least once every two years and review records and procedures implemented by utilities. When violations are detected, the PUCO orders corrective action and may assess fines and other penalties to ensure that Ohio’s natural gas pipeline systems continue to deliver natural gas safely and reliably.

Ohio is home to over 100 unique pipeline operators that operate over 56,000 miles of distribution lines, over 10,000 miles of transmission lines and over 1,100 miles of gatherings lines. The PUCO employs field inspectors who perform compliance inspections of gas pipeline operators to ensure they are following design, construction, operation and maintenance safety regulations.  

What rules and regulations apply to natural gas pipelines?

Natural gas pipeline safety rules are developed by the U.S. Department of Transportation, Pipeline and Hazardous Materials Safety Administration (PHMSA). The state of Ohio has adopted the federal regulations, and the PUCO enforces the regulations through a cooperative agreement with the federal government. Ohio recently extended gas pipeline safety rules to gathering lines used to collect gas from the Utica and Marcellus shale fields that would normally would not be subject to federal rules.

What is the general condition of natural gas pipelines in Ohio?

The condition of Ohio natural gas pipeline network varies by operator. Each operator has the obligation to demonstrate that their piping is in a condition that meets or exceeds the minimum federal safety standards. Most high pressure transmission lines are constructed with protected steel. Lower pressure distribution lines are made from plastic or steel, and older lines may be made from steel, cast iron or copper. Each operator submits an annual report to the PHMSA describing their pipeline network including the type of piping used and number of leaks detected and repaired. This data is available on PHMSA's website here.

Are operators required to replace pipes after they reach a certain age?

The pipeline safety regulations do not specify an age limit for pipelines, but instead rely on performance standards to ensure safety. Among other criteria, pipelines must be protected from corrosion, have adequate wall thickness and be free of dents. Pipeline engineers determine what segments of pipe may be at risk and require further evaluation. The PUCO evaluates this information as part of its inspections.

What extra protections are in place for pipelines running through populated areas?

The pipeline safety regulations require operators to lower the maximum allowable operating pressure of the pipeline, increase the frequency of leak surveys and odorize gas so leaks can be readily detected.

What actions has the PUCO taken to increase natural gas pipeline safety above and beyond the federal pipeline safety regulations?

The PUCO has taken action to have some older piping materials removed and replaced. The PUCO recently required Ohio’s four major natural gas utilities to gradually update old cast iron and bare steel pipelines with more modern protected steel and plastic lines. 

Ohio Main Replacement Programs (Cast-Iron/Bare-Steel*)


Duke Energy

Columbia Gas

Dominion East Ohio


Term of the program

15 years

25 years

25 years

15 years*

Current year of program





Estimated program cost

$716 million

$1.8 billion

$3.4 billion

$337.5 million

Proposed replacement mileage





Miles replaced to date**





Dollars spent to date ^

$678.2 million

$698.9 million

$754.6 million

$110.4 million

Includes bare steel, cast iron, pre-1955 unprotected coated steel, wrought iron, and copper pipe (and associated service lines).

* Original term 20 years, but Vectren stated in Case No. 13-1571-GA-ALT that the program would be completed in 2023.
 ** Mileage is as of 12/31/2014 for Duke, Columbia and Dominion, as of 6/31/15 for Vectren.
^ Dollars include only the cost of main replacements and related service lines

How are new pipelines built? Is there any oversight?

The Ohio Power Siting Board certifies certain types of intrastate natural gas transmission pipelines. Check out the OPSB's fact sheet.