Persistent rainfall has continued rain has complicated the National Transportation Safety Board's (NTSB) investigation into the Feb. natural-gas related house explosion in Dallas that killed a young girl.

The incident claimed the life of the 12-year-old, injured several other people and destroyed a single family home. When NTSB personnel arrived in Dallas Feb. 25, they learned that two other homes in the immediate vicinity had been damaged by two separate explosions/fires two days earlier.

The focus remains on the primary explosion, although the weather has made collecting evidence and excavating pipelines difficult. Nonetheless, agency investigators, along with employees of ATMOS Energy, have been working to identify the location of leaks on the gas distribution main line and collect physical evidence in the area.

A leak has been found at a service tee connection to the home that exploded. This 6-foot long distribution mainline segment has been collected and will be shipped to the NTSB materials laboratory in Washington for examination. The NTSB plans to conduct further pressure tests on customer gas lines at the site in the next three to four days.

(In the NTSB photo above, the failed service tee connection to 3524 Espanola Drive, is tagged with NTSB evidence tags in preparation for transport to the NTSB’s materials lab in Washington.)

NTSB investigators have thus far interviewed 11 Dallas Fire and Rescue department personnel and four ATMOS Energy employees who responded to the Feb. 21 and 22 house fires.

The NTSB will also be looking at the gas company’s integrity management and operations procedures and their response to the accident, as well as the actions of state and local emergency response agencies. The Railroad Commission of Texas and the Pipeline and Hazardous Materials Safety Administration are parties to the investigation and are providing technical assistance and support to the NTSB investigator in charge.

The NTSB says it will release a preliminary report shortly after on-scene evidence collection is completed.