CMA 2017 #264 · Agenda item attachment · Oct 16 2017

City of Cambridge Department of Public Works Owen O'Riordan, Commissioner 147 Hampshire Street Cambridge, MA 02139 theworks@cambridgema.gov Voice: [phone removed] TDD: [phone removed] October 10, 2017 To: Louis DePasquale City Manager From: Katherine F. Watkins City Engineer Re: Council Order O-27, dated August 7, 2017 regarding Gas Leak on Binney Street JULY 28, 2017 GAS LEAK ON LINSKEY WAY (ADJACENT TO 100 BINNEY ST) The July 28, 2017 gas leak on Linskey Way was associated with construction at 100 Binney Street; a 10-story mixed use office and research facility. The work on the building began on the site in June 2015. As of July 2017, the majority of the work associated with the core building permit was complete and the contractor was proceeding with surface restoration along portions of Binney St, Linskey Way and Second St. During the curb and sidewalk work, the contractor proceeded to remove a concrete slab that had been used as a foundation for a material hoist during building construction. It was during the removal of this concrete slab that the rubber tire excavator struck a 4-inch diameter intermediate pressure gas main. This strike broke the gas main and caused the release of gas into the air. The incident is currently under investigation by Eversource Gas and will likley result in a Department of Public Utilities (DPU) Investigation. Obviously, the City will fully cooperate with any DPU investigation and will take any relevent recommendations that such an investigation proposes into consideration as further projects similar to this are considered in the future. The Cambridge Fire Department (CFD) received an alarm at 8:01 am on July 28, 2017 and Eversource Gas was notified of the leak at 8:04 am. The CFD sent mulitple companies into the surrounding buildings and began evacuation of 15 buildings and nearly 4,000 people. The Cambridge Police Department (CPD) provided traffic control to the support the safe management of the site. Eversource Gas arrived on the site at approximately 8:30 am and immediately began working to close valves and isolate the section of damaged gas main. The gas main was isolated and shut off at 9:25 am. Eversource completed the the repair of the gas main at 4:05 pm and restored service to all customers. During the repair work, 4 customers were without gas service. The Department of Public Works (DPW) prioritizes safe construction and the protection of existing utilities during construction for both public and private projects. DPW requires all contractors and utility companies performing work in the public way to be permitted; follow DigSafe protocol; and be properly bonded and insured. Utility companies and major contractors are required to attend weekly construction meetings to coordinate construction activities; participate in safety presentations; identify any utility conflicts associated with their work; and address any community relations issues. Every year DigSafe representatives attend one of the construction meetings early in the construction season to review the requirements for contractors to call in for a DigSafe markout prior to excavation; protocol for maintaining the

DigSafe markings; and requirements for excavating around existing utilities. Furthermore in the Spring of 2017, DPW hosted a damage prevention seminar presented by Eversource with large permit holders before the start of the construction to specifically review safety when working around gas mains. All of these efforts are focused on supporting safe and efficient construction in the public way; and ensuring public safety.