Protecting Groundwater and Wells

Proper well contruction prevents
groundwater contamination.

By Bob Buchanan, Alberta Agriculture, Food and Rural Development Barrhead

Under most Alberta farms there are several potential groundwater sources called aquifers. These aquifers range from shallow sand and gravel deposits to deeper layers of sandstone and fractured shale and coal. On most farms groundwater supply is limited and thus it is very important to protect both the long term supply and quality of these sources.

One of the easiest ways to contaminate a groundwater source is to drill a well. An improperly constructed well can provide direct access for surface contaminants to flow into the groundwater source below. Some chemical and bacterial contaminants can be extremely difficult, if not impossible, to correct by pumping or disinfecting the well. In most cases, the only options to resolve these health concerns are to install costly water treatment equipment or abandon the well.

Most groundwater contamination problems can be prevented by following a few simple guidelines when planning, constructing and maintaining wells. They include:

Select a well-drained site
Locate the well away from sewer systems and livestock facilities where manure can accumulate and seep into the ground
Ensure the well driller disinfects (with chlorine) his equipment both before and during the well drilling process to prevent bacterial contamination
Ensure the well driller installs an effective well seal which prevents seepage water from flowing down the gap between the borehole and well casing
Ensure the well cap is in place and in good condition

Wells and groundwater can also become contaminated in a number of other ways. They include:

Ways	Ways to prevent
Flooded pump pits. Cross contamination from old unused wells. Careless placement or replacement of well pumps and piping.	Replace with pitless well adaptors. Disinfect and properly abandon (ie. fill in) old unused wells. Disinfect all equipment which goes into a well.

Well and groundwater supply can also be reduced in a number of ways. They include:

Ways	Ways to prevent
Improper well development at time of drilling. Overpumping the well Mineral or bacteria deposits on well liner slots and screens can restrict flow into the well. Sediment build-up can also restrict water flow into the well. Reduced infiltration (called recharge) into the ground water aquifer.	Ensure the well driller properly removes fine sediment which can restrict water flow into the well. Ensure the well driller completes a thorough pump test (2 hours or longer) to establish a recommended pumping rate and pump size for the well. Periodically measure the non-pumping water level in the well. A significant drop in this level means a combination of overpumping and/or groundwater depletion. Take steps to prevent and control bacteria, mineral, and sediment build-up. Avoid excessive land clearing and drainage where shallow wells (under 50 feet deep) are the predominant water source.

Ways

Ways to prevent

Improper well development at time of drilling.
Overpumping the well
Mineral or bacteria deposits on well liner slots and screens can restrict flow into the well. Sediment build-up can also restrict water flow into the well.
Reduced infiltration (called recharge) into the ground water aquifer.

Ensure the well driller properly removes fine sediment which can restrict water flow into the well.
Ensure the well driller completes a thorough pump test (2 hours or longer) to establish a recommended pumping rate and pump size for the well. Periodically measure the non-pumping water level in the well. A significant drop in this level means a combination of overpumping and/or groundwater depletion.
Take steps to prevent and control bacteria, mineral, and sediment build-up.
Avoid excessive land clearing and drainage where shallow wells (under 50 feet deep) are the predominant water source.

Remember -- protecting your groundwater sources and wells is essential in maintaining a long term supply of good quality water for your farm. Your children will thank you for protecting this valuable farm resource.

To contact the author, write to Alberta Agriculture, Food and Rural Development, Box 1540, Barrhead, Alberta, T0G 0E0.

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