Bacteria keeps coming back because wells not fixed
April 2, 2015, 11:53 am ADTLast Updated: January 12, 2021, 2:28 pm
Curtis-Steele says if a facility is constantly on the boil order, she would GPS the well and see if it’s too close to contamination sources, such as a septic tank, a farm, or highways.
She would also ask the owner for the well log to examine if the casing is deep enough. Wells drilled after 1973 are all documented in the Environment Department’s database.
Driller Donald Mowat, who owns Mowat’s Well Drilling Ltd. in the Annapolis Valley, has been drilling wells for homeowners and businesses for 50 years.
He says the most common cause of bacteria problem in drilled wells is fractures in the bedrock below the well casing, which allows the contaminated surface water to seep in.
He says it can be fixed by putting in a liner, which is a water-tight pipe put inside the casing.
If it’s a dug well, the bacteria might get into the well water through a crack on the concrete crocks. Mowat says he would either replaces the crocks, or just move over 20 or 40 feet and drill another well.
However, when he gets a call from a water supply owner with a bacteria problem in the well, 99 per cent of the time, he just tells the owner to disinfect the well over the phone.
“Buying chlorine is far cheaper than the machine going in and spend $1,000-5,000 (to install the liner),” says Mowat.
But he says chlorinating the well, which includes pumping chlorine through the system, letting it sit for no longer than 24 hours, and then flushing the water out, only corrects what’s in the well water but it doesn’t fix the fracture on the casing, which means the bacteria will come back.
He says this is especially true with dug wells because they are usually shallower than drilled wells, and are more prone to bacteria from surface water. Whereas the water source of drilled wells is usually deeper than 60 feet underneath the ground, therefore farther from surface water contamination sources.
Further, Mowat says depending on how deep the the water is, in most cases, it costs the same to drill a well and to dig a well, which varies from $3,000 to $5,000.
The majority of the wells in Nova Scotia are drilled. According to data from the Environment Department, among the 117,000 water wells, 96 per cent of them are drilled wells.
Robert Moore, a septic system design engineer for 15 year, says a lot of the four per cent of dug wells have been in place for a few hundred years. And in many cases, they would not meet current requirements for casing to minimize intrusion of surface water.
He says especially as time goes by, wells can become victims of new contamination source.
“I suppose as farms get larger or the pattern of the use of the land has changed. And wells, which may operated satisfactorily 400 years may become contaminated,” says Moore. “Contamination gets into the soil and can migrate very quickly into a water supply system.” That’s why he makes sure his septic design meets the required distance away from existing, proposed wells or other water supply systems.
“If there is no existing wells,” says Moore, “then we would show a possible location for a well on the plan. And then, when the well digger or driller comes along, it’s their responsibility to meet the separation requirements for the well.”
Moore says inspectors from the Environment Department are supposed to come to the the site and measure out the distance before approving the plan and letting the construction to go ahead.
However, Curtis-Steele says according to the division’s internal policy, inspectors only do an on-site inspection for 20 per cent of the plans they receive. For the rest, inspectors just review them on their computer.