Naturally Remediating Soil - Former Gasworks Site

Hi there

I should first point out that I'm asking this to guide an architectural (sorry) university project; it's a conceptual-heavy project only loosely grounded in reality but I would like to justify the design moves that I am making and some help here would be much appreciated.

I am proposing some residential development on an ex-gasworks site in the UK which consists of 2 former gasholders, and ruins of what I assume are boiler rooms/ coal burning facilities. As such I assume there is vast soil contamination. I know in reality this would require extensive soil remediation with treatment technologies; however given that this is a conceptually-driven project I want to use the contaminated areas of land as a site constraint that remains.

I would like to use 'clean' land to support structures that will cantilever over the 'contaminated' land, and propose some kind of natural remediation to the contaminated land and am looking for suggestions. For example, are there any plants/fungi/similar that have purifying effects on soil contaminated by the coal/gas industry?

Hopefully this makes sense and does't contain too much irrelevant waffle about my project.

Thanks for any help
Ryan

"Naturally Remediating Soil" - I don't know... natural would mean no human interference so wait 500 years?

Help me somebody..