I'll start, if I may. Thank you for the question.
It very much will depend on the nature of the site. Sites can range from.... They can be quite simple, like a petroleum hydrocarbon spill that has a limited extent. That's relatively straightforward for contaminated sites experts who are available in the private sector or even within a larger department where they have a fair number of staff with science expert backgrounds.
In other cases, it can be a highly complex mixture of chemicals that risks spread and really needs the benefit of engaging with experts at Environment Canada or Health Canada to be able to determine the risks and an appropriate path forward.