The job of a waste water plant operator is not often thought of as a glamorous one. There are long slow days of monotonous route followed by grueling hours and days of none stop running to prevent a spillage in the even of what's called a high flow. There are days where the operator will come home cleaner than when he arrived at work, and other days his wife will make him undress before he can come in the house.
I've been a waste water treatment plant operator of the past 10 years so I can speak with some experience. The tragic accident in Gatlinburg could and should have been avoided. Simple inspections and even someone with the slightest engineering ability could have told you that any wall, especially a square or with corners, has to be reinforced with fill. This wall was destine to fall with only the re bar holding the back wall in place. I assume that the operators killed were inspecting a leak or the wall was already beginning to lean when it toppled over onto them.
The environmental impact may not be as terrible as many expect although I am simply speaking from my experience at my plant. I will begin with the most obvious the sewage. The sewage that spilled out COULD have only contained about 1/4 sewage WATER and 3/4 storm water. Due to what is called infiltration the intake of a sewage plant will increase substantially in a rain even. This is caused by faulty pipes, illegal gutting hook ups, and open man holes in flood prone areas. Amazingly the open man holes are a HUGE problem. Kids wanting to know what's in them and theft of the lids are the main reason. The night that the wall busted I was working a high flow event and my in fluent (coming into the plant) CL2 (chlorine) was .001 PPM. This level is hardly detectable. The D.O. (dissolved oxygen) in fluent was 2.3. The flow went from a normal 9 MGD (million gallon a day) to 36 MGD. You can do the math and see that the infiltration (which is rain water) was 4 times higher than normal, meaning dilution over pollution.
So the CL2 (again Chlorine) would have created a minimal impact on the aquatic life. The sewage solid waste would have also created a minimal impact due to the river being high and waste solids that could have been in the tank would have been minimal equalling dilution into the river. The D.O. (dissolved oxygen) would have been low however, the oxygen level in the river would have offset that making it's impact minimal. NOW, you may find some non volatile solids such as corn, pill casings, grit, tomato and watermelon seeds, and (I hate to say this but) condoms, and tampons as well in the river.
I believe that the river will be okay and heal it's self in a short period of time with very little actual impact to the aquatic life. If anything there may be an increase in algae due to the over abundance of organic matter for it to feast upon. That should die out once the organic matter dissipates. There is something that not many think about and the state nor EPA has us test for and that's hormones. Your always told to "flush your out dated or unused" pills. Actually I advise you not to because there is nothing at present time that we (plant operators) can do to remove this from waste water and it just continues on down stream. Think about this the next time you empty a pill bottle into toilet.