30 Gal Plastic Barrels. Would you use them?

I have a chance to get a few 15 and 30 Gal Blue plastic barrels for free from a local company. I would love to use them as fermenters for a big batch. The only draw back is they were use to transport Chorine for a local water Coop. The contents of the barrels are turning me away right now. Just wanted to know if there is a way to clean these barrels. I don't even know yet if the chorine is impregnated in to the plastic. Any ideas

Can you remove the lid?

Chlorine breaks down and dissipates in sunlight. I would definitely want to know if the contents were strictly Sodium Hyperchlorite or if there was anything else more sinister blended in.

If it was strictly SH (Chlorine) then I'd suppose you've found some pretty well sanitized bins.

Thanks GilaMinumBeer.. Didn't really want to remove the tops wanted to use the bungholes to fit an airlock.

Could I fill the barrel with water and test the water with a chlorine strip let it sit for a few days in the sun and then test again and get a reading on the level that the barrel had absorbed?

Sure. What do you have to lose. If they don;t test out you can pitch them or use them as rain barrels.