Geochemical Causes of the Pb Water Crisis in Flint, Michigan

Geochemical Causes of the Pb Water Crisis in Flint, Michigan

… How Major Ion Monitoring Can Prevent It

Description:

For a period of a year and a half, from April 2014 to October 2015, residents of Flint, Michigan consumed water, delivered by their water utility, with elevated levels of lead (Pb).  The City of Flint had switched water sources and treatment systems, from a Lake Huron water source, treated, sold and delivered by the City of Detroit, to a local Flint River source, treated in a refurbished water treatment plant that had been mothballed since 1967.  The situation was a stopgap measure while awaiting Flint’s own Lake Huron source, as part of the Karegnondi Water Authority (KWA) pipeline project.  

The Pb was not from either ultimate source, it was from the Pb used in the water mains, laterals, plumbing, pipes, and solder used in the water delivery system.  Eventually the lead (Pb) was discovered in tap water in Flint residences and industries.  Eventually the water source was switched back to Detroit, and in 2019 to the completed KWA.  Nova and Frontline documentaries were aired, conducting a post-mortem on a huge swath of issues, from water quality, the source of Pb from pipe corrosion, the use nationwide of lead service lines and their risks, and alleged government corruption, professional negligence, insufficient regulatory oversite, criminal negligence, and environmental racism or classism. 

Easily missed in the scuffle is a subtle geochemical reaction that increased the corrosiveness of the water:  the precipitation of carbonate.

Dr. John Hoaglund, a geologist, was retained in April of 2020 by the plaintiff attorneys to be their lead water quality expert witness in the main civil trial, and in subsequent bellwether trials.  After an initial settlement of the main case, on August 10, 2020, a settlement with mainly public sector defendants, he testified in the first bellwether trial against remaining defendants, taking the stand March 1st of 2022.

Engineering consultants say government officials lied, caused Flint water crisis

The main presentation in this course, “Geochemical Causes of the Pb Water Crisis in Flint, Michigan”, is based on some discoveries he made reviewing very limited water quality data collected by the Flint water utility.  Some reactions during water treatment caused 1) a drop in pH, 2) the loss of calcium and bicarbonate scaling components, and 3) the loss of ANC (mostly bicarbonate) buffering capacity, increasing the corrosiveness of the water.  The corrosive water caused Pb to dissolve into the drinking water from the walls of the water mains, laterals, and plumbing pipes.

Complete major ion monitoring was not conducted after the switch in water sources.  Given the limited reporting requirements on Michigan’s state forms, these sampling protocols, which should be standard, may not be in place, even currently and in communities outside of Flint, where corruption is often assumed to explain the shortcomings. The subtitle of the course refers to one of its goals, How Major Ion Monitoring Can Prevent It from happening again.

A large portion of the overall course is based on a presentation Dr. Hoaglund made at the National Groundwater Association (NGWA) in December of 2022:  “Changes in Aqueous (Geo)chemistry Leading to Lead Exposure from the Drinking Water of Flint, Michigan”  The abstract to the talk is available on one screen in the presentation, and is also available at the following link:  https://ngwa.confex.com/ngwa/gw22/meetingapp.cgi/Paper/13722

The abstract concludes with the admonition:  “All 8 major ion analyses must become a mandatory part of utility water quality monitoring.”

Learning Outcomes: 

What will students learn in the course?

• Viewers will review why lead (Pb) ended up in Flint’s drinking water (corrosive water leaching Pb from piping and solder in water mains, laterals, and household plumbing)
• Viewers will explore the history of Flint changing their water source and why 
• Viewers will learn how the two sources of water compared, how the geology affected the composition of the “raw” (source) water, and how these differences in water quality are measured.
• Viewers will learn how certain water treatment processes can affect the overall salt composition resulting in reactions that change the salt composition and the critical scaling components:  pH, HCO3, and Ca.
• Viewers will learn about water corrosivity, and the importance of pH, HCO3, and Ca to promote scaling on pipes.
• Viewers will learn about a carbonate precipitation reaction that reduced pH, HCO3, and Ca in the water.
• Viewers will evaluate 3 hypotheses involving the common ion effect that possibly set up the chemical conditions for the precipitation reaction.

What are the requirements or prerequisites for taking the course?

• A general public knowledge of chemistry (high school level) is needed to understand the causes of Pb leaching into the pipes.
• A good high school or entry level college chemistry course would be best for understanding pH, the concentrations of salts and how they might be affected by solubility, acid and base reactions, possible redox reactions, and the net effect of precipitation.  Almost all of the explanations within are at the level presented and explained to “a jury of your peers.” 
• A beginning level aqueous geochemistry course would be ideal to understand the graphical presentation of the data, multiple components in solution, ANC, competing mineral phases, and to evaluate the 3 working hypotheses proposed to explain the setup for the conditions that caused the precipitation reaction. 

Who is this course for?

• This course is intended for the general public for awareness of the issues.  
• This course is also intended for water utility scientists and managers to monitor for similar situations in their water treatment program to prevent similar tragedies. 
• This course is intended for “decision makers” to understand why money needs to be allocated for the critical data that must be collected and analyzed.
• This course is intended generate awareness of the need specifically for major ion analysis, that salts matter: “All 8 major ion analyses must become a mandatory part of utility water quality monitoring.”

Section I: Aqueous Geochemical Causes