Tom,
I used to hold an Ontario public pool operator's cert. They expire if you don't keep them up, just like an ISA cert, so my knowledge is more than a decade old, but I ran a municipal pool, 1/2 Olympic size and a dive tank for several years.
Can't know if this would be the same with your campus pool, but we were required by industry standards to log our water quality readings every 2 hours during operating hours. We had a standard test kit that gave us pH, available chlorine, chloramine (or chlorine that has attached and done it's job) add the two together for total chlorination level.
We also had to log all the other chemicals we added for various reasons. Calcium cloride to raise water hardness so the soft water we received from municipal supply would not eat the grout out of the tiles, Potassium Aluminium Sulphate to aid in particulate precipitation, Muriatic Acid to buffer the pH, various surfactant soaps used to scrub the "scum line", on and on. On demand, if someone had an oopsie in the pool, vomit, poop, blood, whatever, we would shut down, and superchlorinate, up to 20ppm, ten times normal, then partially drain and refill back to the normal 2ppm. Asking your pool operator for a peek at their logs is a good place to start.
All this changes if your pool runs oxygenated Bromine instead of Chlorine. It changes again if your pool uses sand filters as opposed to Diatomatious Earth screens.
Generally speaking, pools run as a closely monitored closed system until it is time to backwash the filters. In backwashing, you shut down the pumps, reverse the valves, restart the pumps and push the days accumulated goo into the sewer. Depending on head count, this can happen nightly. Then, once a year, the pool is emptied for complete cleaning and maintainance of the interior surface and decking. The heat exchangers usually get a good flush at this time, similar to getting your cars coolant system flushed, the effluent from this procedure is contained and disposed of seperately, but trace contaminants remain.
Would I water my garden, nightly, with pool backwash? Good God No, I'd rather you pee on my peonias, assuming you have a functioning liver and gall bladder.
Could an annual pool dump be directed to irrigation? Far less contaminants than a backwash, pretty safe at 2ppm available chlorine, but it's a huge amount of water regardless of quality all at once.
If they are talking a nightly backwash, I'd take the City enviro guy for a walk under those trees and ask him if he'd ask them to drink backwash if they were next to his house.
Northwind.
