Then the material would be Reynolds Polymers, Grand Junction, CO. They are the only company in the country that makes monolithic sheets of cell cast acrylic that big. I'd recommend you call them and ask about material thickness but I'd think 3-4" if they are to be 3 separate viewing panels. If you want - they'll make one panel 30' long but would need to be thicker and the cost goes up up up and they can install the pcs as well, for a fee of course. For that size, I wouldn't use glass at all.
HTH,
James