Seismo-electric technology New method for locating groundwater cites 75 to 90 percent success rate
Farmers are drilling deeper with each passing generation as they look for reliable quantities of good water to support livestock operations.
“It is simply due to the thinking that we can obtain more reliable water and bigger (water) yields by getting away from shallows wells that may be susceptible to surface contamination,” says groundwater specialist Gary Kehler of Longview, Alta.
“Many of the old wells were drilled with equipment not even able to go that deep. In some cases, we are looking for more water in a specific area due to centralization of livestock production requiring one central well that waters 200 cow-calves, which in prior times would have been a number of wells on smaller land parcels.”
New holes cost $35 to $50 per foot, and more producers are turning to science to find the best drill spot.
There’s no indication yet that water witches are applying for employment insurance, but science is definitely gaining a toehold in the once mysterious realm of locating a good aquifer.
The technology used in identifying subterranean water is basically the same as that used in oil exploration 50 years ago. Oil prospectors abandoned the old electroseismic technology because electrical interference tainted their data.
In the past two decades, a British company, Groundflow, has worked with that seismo-electric technology, turning it into one of the primary methods for locating groundwater.
The system produces a sound that impacts the Earth. The seismic impact creates a slight electrical signal if groundwater is present. By analyzing micro voltage at the pickups, the computer can tell the operator if there’s enough water to merit drilling.
The computer also determines the depth and quantity of water.
The operator typically does six to 12 sonar sounding sites on each property and then ranks them from the best to the worst.
Kehler said a sounding site is the next best thing to a test hole.
Kehler is one of those modern day water witches who uses the latest AquaLocate Groundflow GF6 sys-tem. He started his business, WaterFind, 10 years ago in Manitoba.
When he realized there was no money to be made finding water in a province where water often gushes out of the ground, Kehler moved the business to Alberta, where a rapidly expanding livestock sector had bigger demands for water that was becoming more difficult to find.
“In Alberta, drillers find water where I said they would 90 percent of the time. In the mountains, it’s down to 75 percent because it’s harder to decipher information coming through rocks and bedrock. In Saskatchewan, it falls between 75 and 90 percent.”
Kehler concedes that seismo-electric technology is not perfect, but neither is a series of 500 foot dry holes at $50 per foot.
He nearly always works in areas where water is difficult to find, and people usually call him when they are desperate.
His standard rate is $2,100 for southern Alberta, $2,200 for Sask-atchewan and northern Alberta and $2,500 for the mountainous regions of British Columbia and Alberta.
There are hundreds of different rock formations, with varying de- grees of difficulty. He brings data with him from 80 of the most common rock formations found in Western Canada.
“No matter where I am, I always like to see the well logs from previous wells,” he said.
“I work with the landowner and do what research I can to determine the best spots to survey. If none of that information is available, then I go to my rock formation parameters for guidance.”
Kehler drills a one metre deep hole when he has identified sounding sites with the best potential.
He then installs one-metre-deep copper clad rods into the ground about three metres to the left and three metres to the right of the hole. The rods will pick up the return signal from the buffalo gun blast and relay it to the computer.
Then he places a metal disc over the sounding hole and strikes it a mighty blow with a heavy rubber sledge hammer.
“The resonation tells me if I have good connections on all my circuits and if the rods have good contact with the soil,” he said.
“If I don’t get good readings with the hammer, then I know I have to fix things before I proceed to fire the buffalo gun down the sounding hole. I may use the rubber hammer two or three times before I’m satisfied that I’m getting honest readings.
“The hammer also shows me groundwater near the surface. In some conditions, it shows me water as deep as 50 metres. And in the mountains, the hammer and plate can tell me if there’s water all the way down to 100 metres, so it’s a very helpful guide.”
The most important weapon in his arsenal is the 12-gauge black powder buffalo gun, and the most important item of information is logged when he fires it down the sounding hole.
The system works much like radar. The bounce back signal is picked up by the two copper clad rods and relayed to the computer, which is why Kehler takes such care in making sure the rods receive and then relay an honest signal.
“When I fire a shot, it makes the soil move,” he said.
“That creates a micro voltage that can be picked up by the rods. If there’s water down below the hole, it gives off an electrical signal we call a shimmer, which we see on the computer.
“The data logging equipment is triggered when I fire the buffalo gun. It only records for about five thousandths of a second. I typically fire only two shots per hole.
After the first shot, the ground starts to loosen up too much, so it doesn’t give good transmission. The first shot is always the best shot because it penetrates the deepest so the signal gives the best definition.”
Kehler is one of the few operators who loads his own shotgun shells, allowing him to access three different loads for various ground conditions.
He said the data is entered in the computer the nano-second the shot is fired.
However, the field work is only part of the process.
“There’s a fair amount of analysis that needs to be done before I can give the results or recommend which is the best drilling spot,” he said.
“That’s why I never give a recommendation on the day I do the testing. It takes 10 to 14 days to get results back to the landowner.”
Most of the wells in the areas where he concentrates his efforts are categories A, B or C.
Category A wells give up to three gallons per minute, Category B wells yield three to five g.p.m. and Category C wells yield five to 10 g.p.m. Potential categories extend to wells that yield hundreds of g.p.m.
“Anytime I see three or four g.p.m., I automatically apply a risk factor,” he said.
“I advise the client that Category A might mean no water at all or it might be a small isolated aquifer that goes dry in a short period. But a proven pump test of two or three g.p.m. along with a 10,000 gallon tank is good enough for a 100 head cow-calf operation and the family.
“As for depth, I always recommend going to the maximum depth. We always want the well at the bottom of the aquifer, not the middle or the top.”
Kehler said going to the bottom of the aquifer is the only way to be sure the well keeps supplying water when pumped at the recommended rate.
The test should be reviewed by a hydrologist, he added.
There’s always a risk of drilling too fast when drilling Category A or B wells or wells that may be marginal. Low yield wells require patience, and that means a patient driller.
Drilling too fast can “skin off” a low yield aquifer with mud or clay. A driller who is in a hurry might also put the hole right through the aquifer without the client or the driller even knowing water was there waiting for them.
For more information, contact Kehler at 877-388-7388 or visit www.findwellwater.ca or aqualocate.com/.