Issue link: http://read.uberflip.com/i/1051049
USICERINKS.COM NOVEMBER.DECEMBER.2018 / 33 Location of the fans in a recessed area of the roof also prevented exhausted air from reaching the outside airstream and may have directed exhausted ammonia toward air inlets in the arena building. This may have contributed to the ammonia concentration of 400 PPM measured in the arena lobby hours after the incident. It is also possible that ammonia detected in the lobby may have escaped the machine room through a gap beneath the door to the vestibule and an unsealed door between the vestibule and the public area of the arena. Following the incident, first responders opened the emergency discharge valve which released ammonia into the atmosphere, contributing to the declaration of a local state of emergency and the evacuation of 95 residents from 55 homes near the arena. Examination of the system configuration and condition determined that the release of ammonia via the emergency discharge valve did not reduce the risk of ammonia exposure within the mechanical room. Further examination of pipe routing and system requirements concluded that the arena's emergency discharge system introduced additional exposure risk. RECOMMENDATIONS Based on the findings of the investigation, Technical Safety BC made 18 recommendations to improve management of safety risks related to refrigeration systems. These recommendations aimed at arena owners, maintenance contractors, training providers, local governments, and the Canadian Standards Association appear at the conclusion of the report and are published on Technical Safety BC's website at technicalsafetybc.ca. CONCLUSION Technical Safety BC concludes that the equipment failure was caused by a small hole in the curling chiller carbon steel tube resulting from corrosion at a weld seam. Contributing to this failure and the release of ammonia was the: • chiller age and corrosive potential of the chemicals and materials used; • presence of tube weld seam fusion defects; • isolation of the curling brine expansion tank; • isolation of liquid ammonia within the leaking chiller; and • unsupported coupling joints on the brine system pipe. Technical Safety BC concludes that the incident was caused by a decision to operate the leaking curling chiller. Contributing to this decision was a failure to replace the aging chiller after it surpassed its recommended operational life-span. The decision and failure to replace the chiller may have been influenced by: • insufficient hazard awareness relating to leaking chillers and aging equipment; • omission of component end-of-life strategies from the maintenance plan; • employee turnover; • competing organizational and departmental priorities; and • organizational design of the leisure services department. After examination of the detection, alarm, ventilation and discharge systems, Technical Safety BC concludes the following: • the ventilation system could not have prevented a high concentration of ammonia in the mechanical room; • fan location and condition contributed to ineffective ventilation after the release; • fan exhaust location and airflow may have directed ammonia toward building openings; • mechanical room doors presented a path for ammonia to enter arena public areas; and • the emergency discharge did not reduce the risk or amount of ammonia leakage into the mechanical room while introducing exposure risk. J IN RESPONSE TO THE AMMONIA LEAK, THE BRINE SYSTEM AND CURLING CHILLER WERE ISOLATED AND THE REFRIGERATION AND BRINE SYSTEM WERE SHUT DOWN. THIS IMPEDED BRINE EXPANSION AND VENTILATION, AS AMMONIA CONTINUED TO LEAK INTO THE BRINE OVER A FIVE-HOUR PERIOD.