Assume the chemicals have a density of 1 g/cm^3, the same as water, which seems reasonable for organic liquids and such. Then a cubic meter weighs a metric tonne. So 65,000 tonnes is the same as a cube that is 40 meters on a side.
Another visualization: 1/5 of the volume of oil that can be carried by a Very Large Crude Carrier supertanker according to Wolfram Alpha:
http://www.wolframalpha.com/input/?i=65000+m^3
EDIT: Without diminishing the potential gravity of the problem, but trying to visualize what 65,000 tonnes looks like, I'm surprised it doesn't look as big as I thought it would.