The National Transportation Safety Board issued five urgent safety recommendations based on findings from their investigation into the Merrimack Valley gas explosions.
The first recommendation was issued to all of Massachusetts, looking to eliminate the professional engineer licensure exemption for public utility work and a requirement for a professional engineer's seal on public utility engineering drawings.
The other four were issued to NiSource, Columbia Gas's parent company.
The others included:
-Revision to the engineering plan and constructability review process across all of NiSource, Inc.'s subsidiaries to ensure all applicable departments review construction documents for accuracy, completeness and correctness, and that documents or plans be sealed by a professional engineer prior to work commencing.<br/> -A review and of all of NiSource, Inc.'s records and documentation of natural gas systems to ensure they are traceable, reliable and complete.<br/> -Application of management of change process to all changes to adequately identify system threats that could result in a common mode failure.<br/> -Development and implementation of control procedures during modifications to gas mains to mitigate risks identified during management of change operations, with gas main pressures continually monitored during modifications and assets placed at critical locations to immediately shut down the system if abnormal operations are detected.
In their safety recommendation report, the NTSB said omissions in the engineering work package and construction documentation for the project were discovered by investigators, and the omissions were not identified by the Columbia Gas constructability review.
NTSB investigators found the review didn't identify the impact on pressure regulation and control, and the Columbia Gas field engineer who developed the engineering plans told investigators he developed them without reviewing engineering drawings that documented the regulator-sensing lines.
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The NTSB also said they believe a comprehensive constructability review would likely have identified the lack of the regulator-sensing lines and would've prevented the accident from happening.
Investigators also said if Columbia Gas had "adequately performed management of change and placed personnel at critical points along the system," then Columbia Gas could have immediately addressed the problem and "mitigated the consequences of the event."
The full safety recommendation report can be read at https://go.usa.gov/xPGdr.