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Additional Safety Measures Implemented on 72nd Street

Review of the August 21 incident has been completed and blasting will resume on 72nd Street at Second Avenue Subway Site.

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The Metropolitan Transportation Authority (MTA) has announced that the investigation of the August 21 blasting incident has been completed, and that a series of enhanced safety measures and actions have been implemented on the 72nd Street Station Cavern Mining contract. Blasting will resume first in the station cavern on Friday, September 14, and will begin the following week at the ancillary shaft where the August 21 incident occurred.

“We have completed our review of the incident and have implemented a number of corrective actions. From this moment forward, blasting operations will be subject to additional management scrutiny and enhanced safety procedures to ensure that the community and workers are kept safe,” said Michael Horodniceanu, President of MTA Capital Construction.

Improvements to safety include superintendent sign-off on a pre-blast checklist, a second licensed blaster to verify that each blast has been prepared in accordance with the approved blast plans, and a double layer of protective blast mats will be used when blasting in shafts. Additionally, a review of the steel decking system to ensure its ability to withstand uplift pressure has been completed and all personnel responsible for inspecting and monitoring blasting have been retrained.

An independent safety consultant, Thacher Associates/Total Safety Consulting, has been retained to provide outside monitoring of the contractor’s adherence to all safety standards related to blasting.

On August 21, a scheduled blast at the site of the future subway entrance and ventilation building located on the northwest corner of 72nd Street and Second Avenue produced more force than expected, causing a significant amount of debris to be released at street level. All work was suspended immediately. Following the incident, an investigation of the contractor’s blasting procedures was performed. Non-blasting cavern work resumed August 27.

A review of the post blast data found the following factors to have contributed to the incident: failure of the contractor to adhere to the approved blast plan; improper blast timing sequence causing excessive blast force; orientation of the drilled holes, which were angled rather than vertical; use of 10-12 foot long blast holes which may not have been drilled properly; sloped condition of the rock and inadequate rock cover; and failure of the decking system to contain the debris.