Flint Water Pipes: The Science and Politics Behind the Contamination

The Flint water crisis is a stark reminder of the importance of proper water infrastructure. The city's water pipes were made of lead, which is a toxic substance that can leach into the water.

In 2014, the city switched its water source from Lake Huron to the Flint River, which had a higher pH level. This caused the water to corrode the lead pipes, releasing lead into the water. The water was not treated with anti-corrosion chemicals, which made the problem worse.

The city's water pipes were over 100 years old and had been previously coated with a layer of cement to prevent corrosion. However, this coating had worn off, leaving the pipes vulnerable to corrosion.

The city's water was not tested for lead levels regularly, which meant that the contamination went undetected for months.

The decision to switch Flint's water supply from the Detroit Water and Sewerage Department to the Flint River was made in April 2014.

This move was intended as a cost-savings measure, but it ultimately led to a series of problems.

Residents were advised to boil water due to the presence of bacteria, and General Motors reported corrosion on engine parts.

A spike in Legionnaire disease cases raised concerns about water contamination, but investigations were met with resistance.

Elevated levels of carcinogenic trihalomethanes were detected in January 2015, but the city insisted the water was safe to drink.

Later that month, high levels of lead were found in water fountains on the University of Michigan–Flint campus.

The Detroit Water and Sewerage Department offered to reconnect Flint to their system, but the emergency manager declined.

Cost remained the primary decision driver, even as public health concerns mounted.

The city's financial struggles, which began with the closure of General Motors plants in the 1980s and '90s, continued to worsen.

A state of financial emergency was declared in 2002, and executive power was wielded by a manager selected by Gov. John Engler.

This lack of local control and decision-making power contributed to the city's inability to address its water crisis effectively.

In March 2015, a test of the drinking water in one Flint home uncovered concentrations of lead more than 25 times higher than the level deemed actionable by the U.S. Environmental Protection Agency (EPA).

The U.S. Centers for Disease Control and Prevention (CDC) stressed that there was no “safe” level for lead exposure and that the consequences of lead poisoning were lifelong and often debilitating.

EPA regional manager Miguel Del Toral expressed his concerns about the absence of any corrosion control measures in Flint’s water treatment process as early as April 2015.

Michigan’s Department of Environmental Quality (MDEQ) insisted that no additional steps were necessary to mitigate the levels of lead and copper in Flint’s water, despite Del Toral's concerns.

A Virginia Tech professor of environmental engineering, Marc Edwards, determined that the corrosiveness of insufficiently treated Flint River water was causing lead to be leached from aging pipes in September 2015.

Doctors at a Flint hospital told residents not to drink city water after blood tests of area children revealed high levels of lead in September 2015.

Genesee county declared a public health emergency in Flint on October 1, urging residents not to drink any water drawn from the Flint River.

Snyder's office issued a press release claiming that Flint’s water was safe to drink and that elevated lead levels were caused by lead pipes in household plumbing on October 2.

The government response to the Flint water crisis was slow and inadequate.

In 2015, Governor Rick Snyder's administration was informed of the lead contamination in Flint's water supply, but it took months for them to take action.

The city's water source was switched back to the Detroit Water and Sewerage Department in October 2015, but many residents were still exposed to contaminated water.

The state of Michigan ultimately took control of Flint's water system in 2015, but it wasn't until 2016 that the city's water was deemed safe to drink.

The Larson-Skold index is a useful tool for assessing the potential effects of water quality changes on the likelihood of corrosion. It can be used to determine the effect of chloride, sulfate, and bicarbonate/carbonate ions on the corrosivity of treated water toward iron pipes in the distribution system.

The index is calculated as LSI = (Cl−) + (SO42−) + (HCO3−) + (CO32−), where the concentrations are given in units of equivalents per liter. A Larson-Skold index of less than 0.8 suggests that chloride and sulfate levels are unlikely to cause corrosion.

The high values of the Larson-Skold index for the treatment period in Flint should have raised serious concerns about the possibility of corrosion. The index suggests that high rates of iron corrosion should have been expected, which is consistent with the observed high levels of lead in the drinking water.

A high chloride-to-sulfate mass ratio (CSMR) is also an indicator of potential corrosion. The CSMR for the treatment period in Flint was very high in all six samples, which suggests a high risk of corrosion. A CSMR of less than 0.2 is recommended when the alkalinity is less than 50 mg/L as CaC03.

The science of corrosion is complex and not completely understood, but we can break it down into some key facts. The Flint River is naturally high in corrosive chloride, which immediately started corroding iron pipes in the water distribution system after the switch from Detroit water.

Corrosion control occurs when minerals deposit on pipe walls, protecting the iron pipe surfaces from exposure to oxidants in the water. This natural process can be disrupted by changes in water quality, exposing the pipe to corrosion.

The released iron corrosion particles are visible, causing colored and turbid water. This is a common issue in older distribution systems where lead service lines are still in place, leading to the leaching of lead and copper.

Corrosion rates can be affected by many factors, including the presence of bacteria that colonize the pipe wall, pipe age, and water flow rates. These factors are not well-understood, making it challenging to predict and control corrosion.

To mitigate corrosion, some utilities add phosphate corrosion inhibitors to the water. However, this is typically done based on industry experience rather than rigorous scientific calculations.

Here's a summary of the key factors that contribute to corrosion:

The concept of scientific analysis has been around for thousands of years, with ancient civilizations like the Egyptians and Greeks using observation and experimentation to understand the natural world.

The Greek philosopher Aristotle is often credited with being one of the first scientists, using observation and experimentation to develop theories about the natural world.

The scientific method, which involves making observations, formulating hypotheses, and testing them through experimentation, has its roots in ancient Greece.

In the 17th century, the scientific revolution began, with scientists like Galileo and Newton using the scientific method to make major breakthroughs in our understanding of the universe.

The development of the scientific method has allowed scientists to make incredible progress in understanding the world around us, from the smallest subatomic particles to the vast expanse of the cosmos.

The water quality in Flint was a major issue, and it's essential to understand what happened. The turbidity of the raw Flint River water at the FWSC plant ranged from 1.5 to 45.2 ntu, with chloride levels varying from 38 to 82 mg/L.

The treatment process involved several steps, including ozonation, adding sodium bisulfate, ferric chloride, and lime, among others. Water was drawn from the Flint River through raw water screens before being pumped into the ozonation basin.

The treated water's pH and alkalinity varied significantly over the 1.5 years of treatment, with both values being quite low, especially in summer 2015. The decreases in alkalinity from June to July 2014 and over the course of the period from March to May 2015 corresponded to increases in the lime dosage.

The water treatment process at the Flint Water Treatment Plant is a complex one, involving multiple stages to remove impurities and contaminants from the raw water.

Turbidity levels in the raw water ranged from 1.5 to 45.2 ntu from April 2014 to October 2015, with chloride levels ranging from 38 to 82 mg/L.

The treatment process starts with raw water screens, followed by ozonation, where sodium bisulfate is added to destroy residual ozone.

Ferric chloride is then added to the water in a rapid mix tank, before it flows into a three-stage flocculation unit and plate settlers.

An upflow clarifier is next, where lime, anionic and cationic polymers, and fluoride are added to the water.

Carbon dioxide is added in the recarbonation unit to lower the pH, before chlorine is added before dual media filtration and again before flowing into a clearwell.

The treatment train was as shown in Figure 2 as of November 2014, according to the draft Operational Evaluation Report.

The quality of treated water in Flint's River was a major concern. The pH and alkalinity of the finished water varied significantly over 1.5 years of treatment.

For much of the time, both pH and alkalinity were quite low, especially in summer 2015. The decreases in alkalinity from June to July 2014 and over the course of the period from March to May 2015, both correspond to increases in the lime dosage.

The reason for the change in alkalinity and pH after June 2015 is unknown, as the lime and ferric chloride dosages were fairly constant during this period.

The city of Flint's water distribution system was found to have high levels of total trihalomethane (TTHM) concentrations, with some locations having levels as high as 162.4 μg/L in May 2014.

In February 2015, a sample from a Flint resident's home showed lead levels at 104 μg/L, exceeding the 15 μg/L action level.

The 90th percentile lead concentration in Flint's water was greater than in previous rounds of testing, with a significant increase observed by the end of the second six-month sampling period.

Here is a summary of the TTHM concentrations in the Flint distribution system:

The turbidity of the raw Flint River water varied seasonally, with the turbidity of the finished water remaining relatively consistent.

Let's take a closer look at Table 1, which shows the total trihalomethane (TTHM) concentrations in the Flint distribution system.

The table reveals that the TTHM concentrations varied across different locations in the Flint distribution system.

One of the locations, number 1, had a TTHM concentration of 162.4 μg/L on May 21, 2014, which decreased to 67.9 μg/L by August 18, 2015.

Another location, number 2, had a TTHM concentration of 75.1 μg/L on May 21, 2014, which increased to 53.6 μg/L by August 18, 2015.

Here's a breakdown of the TTHM concentrations across all locations:

These numbers give us a sense of the variation in TTHM concentrations across different locations in the Flint distribution system.

Let's take a closer look at the data presented in Table 2, which characterizes the likelihood of corrosion in the treated Flint River water.

The concentrations of chloride (Cl) and sulfate (SO4) in the water varied over the course of the year. In May 2014, the concentration of Cl was 85 mg/L, while the concentration of SO4 was 25 mg/L.

The Chloride-to-Sulfate Mass Ratio (CSMR) and Larson-Skold Index were also calculated for each sample date. The CSMR values ranged from 2.8 to 3.8, indicating a moderate to high likelihood of corrosion.

Here are the specific values for each sample date:

The Larson-Skold Index also varied over the course of the year, ranging from 1.24 to 3.78.

The exorbitant costs of Flint's water crisis are staggering. The city's decision not to use corrosion inhibitors, which would have cost around $140 per day, has led to a massive bill for replacing the lead service lines, estimated at up to $1.5 billion.

This lack of investment in corrosion control management has had far-reaching consequences. Ignorance among utility personnel and water quality engineers of the importance of corrosion control management played a significant role in the crisis.

The costs of the errors made in Flint will reverberate through the community for a long time, dwarfing the original planned savings. The city is now focusing on monitoring, alternative water sources, point-of-use treatment filters, health costs, and restoring the badly eroded trust of the community.

A lack of due diligence in planning will always cost more in the end. Given the complexities and uncertainties in producing safe potable drink, a nonnegotiable respect for the necessary planning and testing steps of any new system is paramount.