> It's unlikely that the thing will burst and disperse all CO2 immediately.

This requires the people running this facility, and all the facilities based on it built by unrelated organizations in the future, to not cut engineering corners on the envelope. I don't take this for granted anymore. But as long as you don't get a big rip, then yeah, it'll be hard to build up a dangerous amount. I wonder if a legally mandatory cut and repair trial on the envelope would reduce risk significantly.

Speaking of wind, I also worry about whoever is downwind if there's a big release. I bet 70m is not quite far enough if it's in the wrong direction.