There has been a lot of finger pointing and hand wringing over last week’s spill of Crude MCHM and the shutdown of the water facility in Charleston, WV. While we are a long way from knowing all of the facts we probably know enough to describe what we would have liked to have happened in this situation.
To do this we will look at consequence and work back upstream (just a minor pun here) to the source of the problem and see what could have been done (in a perfect world) to prevent this problem from happening.
Prevent Crude MCHM from Entering Drinking Water System
The proximate cause of the shutdown of the municipal water system was that it had been come contaminated with Crude MCHM that entered the system through the river water intake. If that intake of contaminated water had been prevented there would have been no major news story and no significant discomfort to the people of the area.
The whole point of having a water treatment plant is to take in contaminated water and make it clean. If we could just drink the river water without processing we could save lots of money. But, almost by definition, river water is contaminated with stuff and the treatment plant removes that stuff. The plant is designed to remove a specific range of stuff that is expected to come down the river, typically the standard animal and plant material (and their normal waste and decay products) that are found in and around rivers.
That treatment process in Charleston did not remove Crude MCHM from the water. There are probably thousands of chemicals that it would not have removed from the water. But, systems to remove everything from the water (okay, no system removes all contaminants from the water, but we are really talking about safe levels of contaminants here) are very expensive to construct and maintain. So you design a treatment system that will remove the chemicals that you reasonably expect to see in the water supply that you will be treating.
The second way that you prevent unwanted chemicals from getting into your drinking water is to stop taking in water when something is present that the treatment system cannot remove. There have been a number of news stories about communities downstream of Charleston that will be shutting down their intakes as the Crude MCHM approaches their water intakes. These communities have an advantage over Charleston; everybody and their grandmother has told them that the Crude MCHM is on the way. Nobody told the water treatment folks in Charleston.
If you don’t get told in advance of a contamination stream that you can’t clean up, you have to rely on inlet water testing to identify such contaminants. This requires two things; first a list of chemicals of concern and second a method to test for them. Now there is something like 80,000 registered chemicals in production/use in the United States (that is a number I have seen tossed around, it is probably not accurate but it is in the right ballpark for this discussion). It is unlikely that any treatment facility knows exactly which of those it can and cannot remove from the water, but again it is unlikely that all of those will head towards your water treatment facility.
Even if you did know (highly unlikely) there are not standard and accepted test methods for detecting each of those chemicals in trace amounts in water. For a very large percentage of them, there is not even a standard for determining what is an acceptable safe level.
The best that you can hope for as a treatment facility operator is to know what could be headed your way and be able to test for that. That means you have to know what is routinely found upstream of your facility, both at fixed facilities and in transportation.
But even then it is not necessarily possible to continuously test for all of those chemicals. Some tests are so complex and time consuming that they consume resources that would make a water system too expensive to operate if testing were done on a continuous or even routine basis. Those tests you only want to run if you have a reason to suspect that that particular contaminant is heading your way. So you have to know about spills and accidents upstream, the sooner the better.
The Perfect World Solution
Okay, for this point in the discussion what would be the perfect solution to the problems that we have identified to this point? Here is a nice start; each water treatment plant would:
• Understand the limits of its treatment process, particularly what chemicals (and at what concentrations) that it cannot remove from the water;
• Know which of those chemicals are found upstream of the treatment plant both at fixed sites and in transportation;
• Know what the safe levels are for those chemicals in the drinking water;
• Have water testing capabilities in place to test incoming water, down to below the safe drinking limits, for those chemicals routinely expected to be found upstream that cannot be removed from water by the current treatment process;
• Have, for those tests that it could not afford to continuously do, a method for determining when that chemical was introduced into the water upstream of the facility so that it could begin testing as the chemical approached the facility.
Obviously, we want to keep these chemicals out of the water in the first place, but we have to recognize that we do not live in perfect world and accidents will happen. Since those accidents are beyond the control of the water treatment facility owners the solutions noted above really should be in place to provide perfectly safe drinking water.
I’ll discuss in later posts what can be done in a perfect world to prevent those chemicals from getting into the water in the first place.