In article , PA
writes
thanks Arthur I did think as much, I was thinking if I planted a perennial
green manure which I could cut down and use as mulch or compost it, do you
think that would be ok or still a risk of contamination, the rubbish that
was dumped looks like household waste, old carpet, and what looked like a
bedroom suite

I seem to recall reading a few years ago about a plant which could be
grown on contaminated land such as old gasworks sites, and which could
stand many times the normal levels of contaminants. They were growing
the plant, which absorbed the heavy metals and other contaminants, and
then taking it away and incinerating it in toxic waste incinerators.
This was supposed to be cheaper (now there's a surprise) than taking off
the top few feet of topsoil and dumping it in a landfill somewhere else.

John

--
John Rouse