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Did The City’s Acid Stimulation Cause Private Well Problems?

Color photography of a rusty water what run from a faucet brown water

(Gillette, Wyo.) Last summer, residents near Carlile began receiving acidic water from their private wells, and some wells were running dry.

Among the impacted residents is Michael Cranston, who told Wyofile in November that the water caused a burning sensation when used to shower and smelled like copper.

The proximity of the problems to the City of Gillette’s Madison Well Field has led to some suspicion something the city did fouled the private wells in Carlile.

The suspicions are further fueled by the fact, as recently as June of last year, the city utilized a common practice called acid stimulation on many of the wells in the field to improve the flow of water out of the formation.

Bill Fortner, a resident of Campbell County, approached the Gillette City Council and the Campbell County Commissioners last week to ask that more be done to help those impacted.

The pins show the wells that the DEQ has tested so far. Carlile is in the top right corner of the map. Image courtesy of the DEQ

The commission has no jurisdiction over the matter, but Commissioner Clark Kissack said the commissioners should use their influence to raise attention on the issue. At the council meeting, Mayor Louise Carter-King said the city was discussing the matter.

The city has not taken a position one way or another on its responsibility in the matter, and officials at the city are waiting to see the results of further testing.

Acid solution

Zeroing in on a culprit will be difficult until the Wyoming Department of Environmental Quality releases results of its tests of private wells in the area later this month. And it’s possible the tests won’t identify the cause. We may never know.

Other possible causes include illegal dumping, other water well activity, and abandoned oil and gas wells.

According to David Simpson, a facilities engineer in New Mexico with 38 years of professional experience in drilling operations, a detailed water analysis in the private wells may show if the solution used in the acid simulation has gotten into the formations the private wells are drawing from.

If fluorene is found in the tests, for example, it points to hydrochloric acid, which was used in the stimulation processes on the wells in the Madison Field, according to Material Safety Data Sheets provided to County 17 by the City of the Gillette.

While it might sound dangerous to use a powerful acid to increase the production of drinking water, hydrochloric acid is also used in a variety of household cleaners and laundry detergents.

Many of the other chemicals used in the acid stimulation process are largely non-toxic. The solution contained propylene glycol, a chemical also used in feedstock and “vape juice,” which vapers inhale.

It also contained ethylenediamine dihydrioiodide, which is also used in pet food and cattle feed. Sodium phosphate, which is used in water and food treatment, and regular bleach were also in the acid stimulation solution.

A schematic of the most recently drilled well at the Madison Field. This well was acid stimulated in the summer of 2017.

How deep?

Simpson said the depth of the city’s wells is important in determining if they’re the source.

According to Levi Jensen, utilities project manager for the City of Gillette, the wells were drilled between about 2800 and 2915 feet below the surface.

Most private wells are 100 to 200 feet deep and draw from formations far above the Madison Formation, where the city is drawing water. And there are numerous formations between the city’s source and the private wells sources.

The chemical solution is pumped down into the well bore to the targeted formations and then it’s pumped back out. By measuring what’s pumped back out, Jensen said, they can be sure what goes into the ground comes back out.

In order to keep the chemical solution from getting into other formations, the integrity of the bore is maintained with layers of casing. The bore hole itself is about 32-inches wide at the shallowest depths and slims down to less than 15 inches at its total depth.

At the depth of private wells, the first casing layer is a cement casing that is 24 to 32 inches thick. An acoustic engineer utilizes a test to ensure this cement casing is bonding to the sides of the well bore. Inside of that is another 24-inch casing, and inside of that is another 16-inch casing.

Before this kind of work can be done, the city had to obtain a series of permits from the Office of State Lands and Investments, the State Engineer’s Office, and the DEQ, among others, for different aspects of the entire project.

The City of Gillette has information on wells 11 and 12 (of 15) on its website.

The DEQ has a page specifically for the testing and analysis of the private wells around the Madison Field.

And you can read the MSDS on the acid stimulation here.