Engineers. There are many different engineers on site: chemical engineers, process engineers and production engineers. They are responsible for running the refining processes as effciiently as possible.
Environmental scientists. The refinery uses thousands of tonnes of water every hour for cooling and for steam. This is cleaned and returned to the environment under the supervision of an environmental team.
Maintanance. The machinery, pipes and equipment on the refinery are all looked after by a maintanance team.