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What causes Flint Water problems Sept 2015 report

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http://flintwaterstudy.org/2015/09/research-update-corrosivity-of-flint-water-to-iron-pipes-in-the-city-a-costly-problem/

Research Update: Corrosivity of Flint Water to Iron Pipes in the City — 
A Costly Problem

September 29, 2015 Siddhartha Roy Articles, Research Updates
Immediately following our research trip to Flint in mid-August, we began 
experiments to quantify the relative corrosivity of Flint River Water 
versus Detroit water. These tests are done in the laboratory so we can 
draw definitive conclusions. While such testing is almost always done 6 
months to a year before switching a water source to anticipate and avoid 
unexpected problems, in this case we are doing it more than a year after 
the switch to examine “What went wrong?.”

Recent news is correctly focused on the very high corrosivity of Flint 
River water (without any inhibitor) for lead plumbing, and the 
likelihood that the resulting higher lead in water is associated with 
increased blood lead for Flint’s children. However, iron corrosion is 
also a major problem, and herein, we report our final experimental 
results on this issue. Corrosion in general, and iron corrosion in 
particular, is the most expensive problem that water utilities face. 
Rapid iron corrosion can easily cause tens of millions of dollars’ worth 
of damage per year to Flint’s water mains, so we wanted to examine how 
bad the problem was.

Hypothesis: It was hypothesized in our National Science Foundation (NSF) 
proposal, that Flint River water alone would be about 5 times more 
corrosive than Detroit water. However, no corrosion inhibitor was added 
to Flint River water, which could make the difference even greater. 
Morever, certain bacteria that can speed up corrosion, can grow in pipe 
systems, and essentially cause iron pipe to be “eaten up” faster than 
without these bacteria. This is called Microbiologically Induced 
Corrosion (MIC). During our field sampling a month ago, we looked for 
MIC bacteria in the Flint system versus samples from Detroit, to see if 
there were problems due to MIC bacteria.

Result #1.   Head to head comparison of iron corrosion in Flint River 
vs. Detroit Water.

We previously demonstrated that rapid iron corrosion in Flint River 
water was eating up the chlorine disinfectant, and causing much more 
iron release than in Detroit water. We continued the same test for a 
month, exposing steel samples (a nail that is 99.99% iron) to: 1) 
Detroit water, 2) Flint River water, and 3) Flint River water plus 
orthophosphate (a known corrosion inhibitor). The water contacting the 
steel was changed every Monday, Wednesday and Friday. After a month, we 
photographed the iron samples, and measured weight loss. Each experiment 
was conducted in groups of three (triplicate) so we could estimate the 
corrosion rate with statistical confidence.

There was much more rust on the nail exposed to Flint River water 
compared to Detroit water (Figure 1). This gives you an idea why General 
Motors had to stop using Flint River water, because it was eating up 
metal on their assembly line.

Figure 1. Illustrative photograph of a nail after 1 month exposure to 
Detroit water (above) and Flint River water with no inhibitor (below). 
Each nail was rinsed in flowing water before taking the picture.
Figure 1. Illustrative photograph of a nail after 1 month exposure to 
Detroit water (above) and Flint River water with no inhibitor (below). 
Each nail was rinsed in flowing water before taking the picture.
The weight loss measurements of the nail were used to determine the rate 
at which the water ate away at the steel, and verified scientific theory 
and our experimental hypothesis (Figure 2). Flint River water is more 
corrosive even with phosphate added than Detroit water (which has 
phosphate). In fact, Flint River water plus phosphate had 3.5 times more 
weight loss than the Detroit water, which is reasonably close to the 
theoretical prediction of 5X more corrosive noted in our NSF proposal 
(Figure 2). Theory says this is due to the higher levels of chloride and 
sulfate in the Flint River water than in the Detroit water. If an 
orthophosphate corrosion inhibitor was being added to Flint River water, 
in the last 16 months the city pipes would essentially have aged about 
56 months (56 months = 3.5 faster corrosion X 16 months) more than if 
Detroit water was used.

Unfortunately, the Flint River water was added to the pipe system 
without any phosphate inhibitor. In our tests, this condition was 8.6X 
worse than Detroit water (Figure 2). Assuming this rate applies to the 
actual city pipe system, the last 16 months on Flint River water would 
have aged the pipes about 138 months (138 = 8.6 X 16 months) or 11.5 
years more than using Detroit water. This could easily be costing 
citizens of Flint millions and millions of dollars in future pipe repair 
costs (see later discussion).

Figure 2. Iron corrosion rate based on weight loss after 1 month in 
Detroit, Flint River, and Flint River water plus orthophosphate (1mg/L 
as P).
Figure 2. Iron corrosion rate based on weight loss after 1 month in 
Detroit, Flint River, and Flint River water plus orthophosphate (1mg/L 
as P).
Result #2: Microbially Induced Corrosion (MIC).

The above results are bad enough, but they do not consider problems 
caused by bacteria that can further accelerate metal pipe corrosion. 
When we went to Flint, we brought Biological Activity Reaction Test 
(BART) kits to look for specific MIC bacteria including: heterotrophic 
aerobic bacteria (HAB), acid producing bacteria (APB), iron reducing 
bacteria (IRB), sulfate reducing bacteria (SRB), and slime forming 
bacteria (SLYM). As a scientist, it is fun to do these tests, because 
when the bacteria grow one can see colors either appearing or 
disappearing to indicate that they are present (Figure 3). Depending on 
how fast the color changes, one can also roughly tell how much of each 
bacteria type are present—if there are more bacteria the color changes 
more quickly. For example, HAB tests have a color blue without bacteria 
(upper left Figure 3) and it will turn clear if bacteria are present and 
grow (lower left Figure 3). Or the SRB test bottle is clear if there are 
no bacteria (upper black cap bottle Figure 3) and will turn black if the 
bacteria are present and grow (lower black cap bottle Figure 3). The key 
point is that all types of corrosion causing bacteria were found in the 
Flint system (comparing top bottle with no bacteria to bottom bottle 
from Flint tap water of the same color cap). This is probably due to low 
chlorine, but might also be due to Flint River having a lot of organic 
matter (or “food”) for bacteria in it. We took a few samples of Detroit 
water, and the levels of corrosion causing bacteria were much lower.

Figure 3. Bacteria tests from right to left for HAB, APB, IRB, SRF and 
SLYM. The top bottles show what no or low levels of bacteria look like. 
The bottom bottles (all from the Flint system) show a color change 
indicating the corrosion causing bacteria are present.
Figure 3. Bacteria tests from right to left for HAB, APB, IRB, SRF and 
SLYM. The top bottles show what no or low levels of bacteria look like. 
The bottom bottles (all from the Flint system) show a color change 
indicating the corrosion causing bacteria are present.
We cannot say for sure that these bacteria were not in the Flint system 
at high levels if the Detroit water was still being used. But we 
strongly think that there would have been a lot fewer of them. In 
general, it is believed that the more MIC bacteria you have, the more 
problems you will have with excessive iron pipe corrosion. So the 
earlier estimates of corrosion rate, as bad as they are, might even be 
worse in the real Flint system when the bacteria are present.
Commentary: The High Costs of Pipe Corrosion and Importance of Corrosion 
Control

As a “back of envelope” illustration of how expensive corrosion is, 
let’s do some math that is grounded in some real numbers. It has been 
estimated that it would cost about 1.5 billion dollars to replace all of 
the pipes in the Flint distribution system. Assuming that cost can be 
(optimistically) spread out over the next 50 years, the cost per year to 
Flint residents would be 30 million dollars per year. Assuming there are 
30,000 ratepayers, this translates to about $1000 per rate payer per 
year ($83/month per ratepayer). So right away, you get some insights, 
into why water rates are so high in Flint!

But now, instead of spreading that payment out over 50 years, it might 
have to be spread out over only 38.5 years (50 yrs – 11.5 yrs = 38.5 
years) because of the corrosion damage done and pipes failing sooner. 
Remember, we have aged the system 11.5 years or so in just 16 months. 
This would mean that pipe replacement costs would have to go up to about 
39 million a year just to keep up with failures. Thus, costs to 
ratepayers would be $9 million extra per year for the next 40 years, 
because of the extra corrosion that occurred by Flint River water 
without inhibitor.

While this is a very crude analysis, it does illustrate why corrosion 
problems not only endanger public health, but they are also extremely 
expensive. Every dollar spent on corrosion control usually saves at 
least $5-10 in damage, and future repair costs at a typical utility. For 
Flint, it is quite possible that the damages from corrosive water could 
ultimately be in the range of a hundred million dollars or even more. On 
top of that, this analysis does not consider damages to consumers 
plumbing, which tend to be even more expensive. This is a serious 
problem indeed, and casts the initial idea that switching to Flint River 
water would save money in serious doubt. In fact, it is highly likely 
that the switch will end up costing future citizens of Flint, millions 
and millions of dollars.

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What causes Flint Water problems Sept 2015 report Sergio <invalid@invalid.com> - 2016-01-21 15:00 -0600
  Re: What causes Flint Water problems Sept 2015 report jimp@specsol.spam.sux.com - 2016-01-21 23:23 +0000
    Re: What causes Flint Water problems Sept 2015 report Sam Wormley <swormley1@gmail.com> - 2016-01-22 14:01 -0600
      Re: What causes Flint Water problems Sept 2015 report jimp@specsol.spam.sux.com - 2016-01-22 20:25 +0000

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