Hierarchy of controls in Contra Costa Health Services (CCHS) incident investigations

Industrial safety ordinance (ISO), implemented in Contra Costa County in 1998, and in the city of Richmond in 2000, expands on the California accidental release program (CalARP) and requires the consideration of inherently safer design (ISD). Identifying ISD-based corrective actions as part of incident investigations is an opportunity to consider ISD within the existing process safety management framework. The objectives of this work were to analyze corrective actions from ISO incident investigation reports with respect to the hierarchy of controls, to identify additional ISD-based corrective actions for an incident using the ISD bow tie protocol, and to develop additional ISD example-based guidance. Thirty incidents from 2001 to 2018 were analyzed, and 227 recommended corrective actions were documented and categorized according to the hierarchy of controls. An incident at the Tesoro Golden Eagle Refinery on September 15, 2004 was analyzed, and five additional ISD-based corrective actions were identified. This work suggests that using the ISD bow tie protocol and example-based guidance, in addition to ISD checklists and guidewords in incident investigations could help identify more ISD-based corrective actions.