Water well venting - graphics credit to Alberta Agriculture

By Dori Modney with files from Alberta Agriculture

Dealing with gases in groundwater

Nov 10, 2020 | 11:20 AM

EDMONTON, AB. — In many cases, it`s just annoyance and in others, it can be a deadly situation. Gases can occur naturally in farm and acreage water wells. The gases dissolve in the water while under pressure and are released when pumped out of the well.

Shawn Elgert, agricultural water engineer with Alberta Agriculture and Forestry, notes people can complain about the smell, but the gases you can`t smell may cause the worst problems.

‘Odourless gases include carbon dioxide, methane and nitrogen, and potential dangers may arise from them. Water wells that `breathe` have been fatal in the province.

‘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.’

Elgert explains that an older basement pressure tank or cistern that isn`t vented to the outside, will have gases collect in the basement. However, modern pressure tanks don`t have a relief valve, so this problem does not occur with them. Another danger is the presence of a combustible gas, such as methane. A strong enough concentration could result in an explosion. Elgert explains how one well owner experienced this danger first-hand.

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“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, creating 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 injuries.“

Some tips to prevent gases in water wells from creating issues for people who rely on them for their homes and farms:

— ls 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.

Read more:

Gas in your Water Well

Dissolved Gases in Well Water

Water Wells that Breathe

To speak with a water specialist, connect with the Alberta Ag-Info Centre:

Hours: 8 am to 5 pm (open Monday to Friday, closed statutory holidays)
Toll free: 310-FARM (3276)