This is a re-post of a comment that I made on my Facebook profile a couple of months ago regarding the temporary dumping of raw sewage into the local river by a city near where I live. There was a fair amount of buzz around this issue, which in the end, I can understand the need to discuss, but was seemingly blown out of proportion.
I’d like to preface this with saying I am totally, 100% against the dumping of raw sewage into our rivers and lakes as a policy. And 8 billion liters sounds like an awful lot of raw crap to be dumping in our river. The St. Lawrence flows at a rate of approx. 16800 cubic meters per second. This is the amount of water if you picked a point along the river and measured the volume of water that passed across that point in 1 second. And that’s every second (and it obviously changes with seasons). So how long will it take to “flush” the 8 billion liters of crap the City of Montreal wants to dump in the river? Well, there are 1000 L in 1 cubic meter, so 8 billion liters can be converted to 8 million cubic meters (still horrifying!). To find out how long it takes the St. Lawrence to move 8 million liters, we divide 8 million by 16800, which gives us… 476 seconds. That’s about 8 minutes. I believe the City wants to dump this sewage over a 1 week period, so if we assume they do it evenly (which of course is a guess, I’m sure it will vary), that means 8 million cubic meters divided by 7 days, giving about 1.2 million cubic meters per day. Divide that by 24, you get 50000 cubic meters per hour. Divide that by 60, you get 833 cubic meters per minute. Divide /that/ by 60, and you get about 14 cubic meters per second. That’s a lot of crap. But considering even if the 16800 cubic meters per second flow rate is off by 100 (so 168 cubic meters per second instead), the river will wash that crap towards the ocean in about 1/100th of a second after dumping it. This is a travesty if it were done on a daily basis as a policy. But as a once in a while thing? I’m not so sure it’s all that important to get terribly worked up over. I will leave it to you the reader to figure out where that sewage would normally go if it was extracted from the waste water when all the sewage handling systems are working. The answer might surprise you.