New technology is helping scientists find drinking water that may reduce potential shortages in the Midwest. The Great Lakes Radio Consortium’s Charlie Schlenker has more:
Transcript
New technology is helping scientists find drinking water that may reduce potential shortages in the Midwest. The Great Lakes Radio Consortium’s Charlie Schlenker reports:
(in with sound of hydraulic lift)
It’s an unseasonably warm afternoon near the banks of the little Kickapoo Creek south of Bloomington, Illinois, but rather than basking in lazy-day-sunshine, workers are using a hydraulic piston to slam a hundred-pound metal post into a titanium plate on the ground.
(sound of plate slamming)
Before the pounding began, workers for the Illinois State Geological Survey strung a nearly 500-foot chain of ultra-sensitive microphone pickups on either side of the mechanism. Geophysicist Andre Pugin says they use a seismograph hooked to those microphones to record images of the sound echoing off bedrock and sediment left by glaciers long ago.
“You can see we can find the old channels, filled again here more recent sediments, and you see here very well the bedrock surface which is very flat and continuous and with this technique you have a very high resolution and very good resolution underground.”
Those old channels are underground stream beds that running water scoured into the bedrock more than a half a million years ago — long since filled and covered by glacial refuse, but even with the refuse choking the streambeds, there is still room for water to collect and flow, in what are natural storage areas for fresh water, called aquifers. All this lies under the fertile soil created by thousands of years of prairie growth.
State geologist Bill Shilts says the survey is using this unusual technology to map sections of the Mahomet Aquifer running under central Illinois.
“The Ohio River actually cut through the middle of Ohio, Indiana, and Illinois and was shoved south by the glaciers probably over five hundred thousand years ago. Underneath our feet are the gravels that were deposited in that river valley and that basically is the Mahomet Aquifer.”
The Mahomet Aquifer runs from the Illinois River east through Indiana and Ohio all the way into West Virginia where it’s called the Tays Aquifer.
Another geophysicist, Tim Larsen, says they can record a mile and a half a day of underground contours. He says this adoption of oil industry exploration technology is a huge improvement over earlier versions.
“It’s not as fun as shooting dynamite, but it goes a whole lot quicker because with dynamite you had to drill a hole down about five feet into the ground — put the dynamite in — and stand away from it.”
On this day, a nearby farmer is using a chisel plough on his field and there are four excavators in the distance preparing ground for a new sewage treatment plant. Larsen says that’s causing interference.
“This seismograph system is set up so that if you re walking along the line that will interfere with it. If you have a cat walking along the line, that will interfere with it and cancel out our signal. The signal we’re looking for is very small and very, very sensitive.”
Scientists hope that if managed carefully, the underground river could be a primary source of water for many cities in the states through which it runs. State geologist Bill Shilts says about 30 or 40% of Illinois residents already use groundwater supplies for their drinking water, and the rest are mostly concentrated in Chicago and are using Lake Michigan.
“But by international treaty and law we are only allowed to take a certain amount out of Lake Michigan, which we are at the limit already, so any expansion in the Chicago area is going to require ground water and there is already considerable concern about that now.”
Experts predict water consumption in the Great Lakes states could rise nearly 1.3 billion gallons per day by the year 2015, and while that is less than 2% of overall use, Shilts says there isn’t all that much to spare right now.
“And it’s not just the quantity of the groundwater, it’s also the quality. Water issues will be probably worldwide major issues over the next fifty years but particularly in these areas of high population density.”
(out with sound of hydraulic lift and hammer)
Shilts says using the seismograph and sledgehammer
approach at the present rate it would take 400 years to map all of
Illinois, but Illinois, Ohio, Indiana, and Michigan, along with the U.S.
Geological Survey are hoping to attract up to $20 million a year in
federal funding to chart high priority areas around big cities and in
transportation corridors to complete the work more quickly.
For the Great Lakes Radio Consortium, I’m Charlie Schlenker.