Dealing with Contaminated Land
In terms of the redevelopment of contaminated land, it is typically the developers who fund the cost of ensuring that the site is suitable for use.
With regards to historic contamination, or that encountered under the Part IIA of the Environmental Protection Act, the 'Polluter Pays' principle applies.
It may simply not be possible to say who caused the contamination or the company may have gone out of business. In this situation you may be responsible for any costs of remediation if you own or occupy the land even though you did not contaminate it and did not know it was contaminated.