Gases in groundwater

  From the November 5, 2018 issue of Agri-News
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 Gases in water wells can cause some issues for people who rely on them for their homes and farms. Shawn Elgert, agricultural water engineer with Alberta Agriculture and Forestry, outlines some of the problems and offers some solutions.

Gases can occur naturally in water wells. The gases are dissolved in the water itself while under pressure and be released when pumped out of the well. “Sometimes people complain about the smell, but the gases you can’t smell may cause the worst problems,” says Elgert. “Odourless gases include carbon dioxide, methane, and nitrogen, and potential dangers may arise from these gases in the water.”

Elgert says that water wells that “breathe” have been fatal in Alberta. “On a low pressure day, gases can come out of the well head that can contain very little oxygen. If the well head is inside a pump house, in the basement of a house - or even worse - in a pit, the oxygen in that enclosure can be displaced. It only takes a short time for a person in that enclosure to lose consciousness or even die if they breathe in this gas with little oxygen – even less time than if they try to hold their breath.”

“If an older pressure tank or cistern is in the basement and is not vented to the outside, gases can collect in the basement,” he says. “However, modern pressure tanks do not have a relief valve, so this problem does not occur with them.”

Another danger is when a combustible gas - such as methane - is present. A strong enough concentration could result in an explosion. Elgert explains how one well owner experienced this danger first-hand. “He was venting the gas out of a pressure tank inside a pump house because he thought the pump was introducing air into the water. He was near the pump when it kicked on, created a spark, ignited the gas, and blew up the pump house while he was still inside. He was fortunate it was such a short burn and he only sustained minor peeling of skin from his face after the incident.”

Elgert adds that overpumping the well can make this problem worse especially when the water level is drawn below the top of the slots or holes in the casing where the water enters the well.

“Other problems can occur on a high pressure day in winter,” notes Elgert. “Air can go down into the well, freeze the pitless adapter, and stop the water from pumping. Gases causing spurting from taps and loss of prime of the pump is another problem.”

As for solutions, Elgert offers these tips:

    • Wells in pits should only be worked on by someone with confined space entry training. Well drillers use gas meters to determine if there is enough oxygen in the pit before entering. The meters also test for some other gases including combustible ones.
    • Existing wells in pump houses or unsealed wells in basements should be capped properly and vented safely to the outside. Older style pressure tanks in basements that can vent off should be vented to the outside.
    • Overpumping the well can intensify the problem. An assessment of the well can be done to determine a system that would reduce overpumping.
    • Collect a sample with an appropriate method and send it to an accredited laboratory for analysis.
Find more information about Gas in your Water Well, Dissolved Gases in Well Water and Water Wells that Breathe. To speak to a water specialist, contact the Alberta-Ag Info Centre at 310-FARM (3276).

Alberta Ag-Info Centre
310-FARM (3276)

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For more information about the content of this document, contact Shawn Elgert.
This document is maintained by Christine Chomiak.
This information published to the web on October 30, 2018.