Pipeline inspected after explosion

INDIANAPOLIS (WISH) - There is still no official word on what caused the explosion Saturday night in the Richmond Hill subdivision on the city's south side, but natural gas is suspected of playing a role. However, evidence is mounting against a ruptured underground pipeline being the likely source.

The Pipeline Safety Division of Indiana’s Utility Regulatory Commission remained at the scene investigating on Monday, alongside investigators from the U.S. Department of Transportation (USDOT) and National Transportation Safety Board (NTSB). The USDOT has regulatory authority over all natural gas pipelines across the country, said IURC Pipeline Safety Division spokesperson Danielle McGrath.

“We also have the authority to investigate, and we are working with those other agencies and the utility now on the ground to see if a pipeline was involved,” McGrath told 24-Hour News 8.

It is still too early in that investigation to pinpoint an exact cause, McGrath said.

“But, we have seen nothing unique in that neighborhood as far as pipelines go,” she added.

Investigators are using a number of tools to begin ruling causes out, however.

The National Pipeline Mapping System shows the approximate locations of high pressure natural gas transmission lines across the country, including three that pass through Indianapolis. The Indianapolis metro area gets its natural gas from large supply lines, which are then compressed at one of three local compression plants, run by Panhandle Eastern, Texas Gas Transmission and Rockies Express.

Some of the larger supply lines do run through local neighborhoods.

Two of those large diameter lines are shown on the mapping system as running within a mile of the Richmond Hill subdivision, but none are shown passing directly under it.

Indiana’s GIS mapping system also shows natural gas utility lines running near both Southport Road and County Line Road. But again, the maps do not show specific transmission lines running into the subdivision.

Other evidence against the involvement of a large scale gas pipeline rupture comes from the scene itself.

On September 9, 2010, a 30-inch natural gas transmission line ruptured in San Bruno, California. Dozens of homes were leveled by the blast, and many more were damaged by intense fires that broke out following the blast.

The force of the impact from the underground pipe left large craters in the ground in the area of the San Bruno explosion. Aerial video taken from Chopper 8 in the Richmond Hill subdivision does not appear to show the same type of ground disruption, though much of the area remains covered in debris.

Citizens Gas spokesperson Sarah Holsapple said late Monday that the utility had tested small diameter transmission lines running to the neighborhood on Monday and found no leaks. Those tests do not show if a line was leaking going into a specific home, however. Tests to determine that are now under way, Holsapple said.

“The jurisdictional responsibility changes there,” McGrath said. “The lines going up to a home are the utility’s responsibility [to maintain]. Anything inside the home is the homeowner’s responsibility. Right now, it’s still too soon to know if either of those lines were involved, or even if natural gas was involved, but we are working as quickly as possible to get answers.”