Hierarchy of Controls Analysis (HCA)

Hierarchy of Controls Analysis aims to reduce the risk involved in a process by implementing the principles of Inherently Safer Design.  The Hierarchy of Controls is often presented as an inverse pyramid similar to the one shown below:

The hierarchy has been developed such that controls which lie higher on the inverse pyramid (e.g., Elimination) are more effective at reducing risk than those which lie near the bottom.  Typically, when evaluating preventive measures, those near the bottom are the cheaper and easier to implement, but they do not provide the robust protection of those in the upper tiers.

We have developed a method to comply with HCA requirements of applicable regulations.  Our method balances risk and feasibility.  When conducting HCA, the design (or proposed design) of a process is reviewed using a systematic methodology to identify areas of design improvement which fall as high as possible on the hierarchy of controls.  The goal of the HCA is to ensure that implemented safety measures have considered inherently safer design philosophies, and, where possible, to reduce the risk.


  • Facilitated HCA for a number of process units at a major petroleum refinery as part of the five-year Process Hazard Analysis revalidation cycle.  The HCA methodology involved a two-part approach.  The design of each unit was first reviewed at the PFD level to investigate potential inherently safer improvements to the existing process.  Additionally, the HCA methodology was applied to each of the recommendations proposed as part of the unit PHA and LOPA studies.
  • For several large water utilities in Southern California, developed an integrated program addressing PSM, RMP and CalARP, which included wastewater and potable water treatment sites.
  • Conducted HCA on proposed design changes as part of the Management of Change process at a major petroleum refinery.