Many sewer treatment plants have huge chlorine Tanks on their properties. These tanks contain large amounts of Chlorine Gas. These tanks should have barriers around them to prevent a truck from driving into them, as series of ditches and berms as part of the landscape is a good start. But also double walled tanks like on Oil Tanker ships.
Should we add protective coatings, which contain chemical membranes which can attach the escaping gas between the walls. So an explosive device would cause the membrane to heat up and other gases could combine with the Chlorine Gas to prevent problems. Many POTWs do not use much Chlorine Gas which means that such huge tanks are not on the property. A huge Earthquake or attack could cause the escaping gas to flow with the relative winds into populated areas. We need these upgrades. As we know that International Terrorists like to use the infrastructure against us.
Normally the inlets and valves have automatic shut offs and warnings alarm to protect workers to get out of the way, but trying to get a whole city to evacuate quickly may not be possible.
We should continue to improve our infrastructures to be mother nature proof and nearly impossible to be used against us in the event of an International Attack.
The Industry has done so much and many facilities are International Terrorist proof thus eliminating them from contention, but not all are. We might wish to expedite these upgrades as needed.