NTSB investigation: pipeline that exploded near Hayward installed in 1940s
ASHLAND — The natural gas pipeline that exploded Thursday morning near Hayward was installed in the 1940s and was damaged during recent road construction work, according to a National Transportation Safety Board preliminary investigation.
The findings come just days after a line carrying natural gas line that was inadvertently cut and in the process of repairs exploded, a blast that sparked a three-alarm fire in a neighborhood in Ashland and injured six people.
The NTSB, a federal agency tasked with investigating incidents including pipeline issues, arrived at the site of the explosion around 11:30 a.m. Friday and completed a preliminary review of the construction work and damaged pipeline, Peter C. Knudson, media relations representative for the NTSB said.
The agency plans to work at the site for an additional five to seven days; a final report outlining the likely cause of the explosion and any factors that played a role will take between 12 and 24 months, Knudson said.
Two steel pipelines located near the explosion — one with a three-quarters of an inch diameter and the other a two-inch diameter — were installed in the 1940s, Knudson said.
The natural gas pipeline was damaged while crews completed grading work on the street in front of the house as part of a road improvement project, Knudson added. A Pacific Gas & Electric Co. spokesperson earlier said utility workers were called in to identify a leak after a third-party construction crew struck an underground gas line in the area.
The blast happened on the 800 block of East Lewelling Boulevard in Ashland, an unincorporated area near Hayward.
As part of the probe, NTSB investigators will collect evidence related to the damaged pipeline, as well as expose and test it, Knudson said. The investigators will create a timeline of events that lead to the explosion, including the timing and notifications of the damage.
The team will also review one-call records and gas facility records, as well as conduct interviews with PG&E employees, construction workers and first responders. Investigators will also review the construction methods used, Knudson added.
The preliminary report will be made available on NTSB’s website and will include the information gathered in the initial investigation, Knudson said.