There are common approaches used—for example, removing contaminated soil from the site and taking it to a certified disposal facility where it can be treated. Another technique that's commonly used is pumping, cleaning and returning groundwater. Working it through filters is part of that process. There can be various barriers and things that are put up to allow for treatment as well.
There's a mixture, but there are common ones that get used. As to whether they work specifically in a context, that can be very site-specific.