Welding ground...don't do this!
On the chlorine gas, it's not any worse than putting 110 gallons of 18° Baumé hydrochloric acid into a one million gallon/day high rate anthracite/sand filter and letting it sit for 2 hours and then backwashing it out. An evil white fog of hydrogen chloride and chloramines inside the filter room. And better yet, out across the waste sedimentation ponds and down the creek. I guess it dissipated by the time the creek got near the homes along the bank. Some utility superintendents don't need to be in charge of a deep fryer at a McDonalds...