Bryan Times, Aug. 25, 2018 (report by Josh Ewers, Science and law are topics; Hydrologist speaks of Michindoh aquifer) Only new test data can definitively prove what effect Artesian of Pioneer’s plan to drill into the Michindoh aquifer will or will not have on the aquifer as a whole, and individual wells.
… In that vein, a hydrologist recently talked to a group in Angola, Indiana, about factors that will ultimately come into play, a lack of regulation on ground water, and how an aquifer functions.
Hydrologist Jack Wittman, Ph.D., vice president and Midwest principal geoscientist at Intera GeoScience and Engineering Solutions explained that an aquifer is a layer of sediments found above bedrock.
“In between this material, there’s a lot of stuff In here that is definitely not aquifer material,” said Wittman. “It’s sand and gravel interspersed with clay.”
According to a U.S. Geological Survey of the Michindoh from 1984 to 1986, that layer ranges in thickness from 80 to 320 feet in Williams County, based on the assessment of 87 wells and several thousand well logs.
… The recharge rate for the aquifer varies based on a number of factors and by section of the aquifer, from 2 to 8 inches a year, according to numbers produced in 1977 (Pettyjohn & Hemming) cited in both the 1984-1986 USGS study and a 2007 study conducted by Tritium Inc.
According to the latter, over 50 percent of Williams County’s portion of the aquifer’s recharge comes from precipitation, and the other portion from groundwater flow from the northwest.
The 2 to 8 inches of recharge is compiled with a number of factors playing a role, some of which have changed quite a bit since 1977.
For one, there’s the proliferation of drainage tile and tillable land use in the county, which could potentially further limit the amount of precipitation making its way down to the aquifer, according to Wittman.
“Tiling fields does one huge thing. It changes the amount of water that you can store in your aquifer,” said Wittman. “Tile drains take off water that would’ve bulged up as you get more and more recharge. It drains that top down and reduces the amount of water you can store in an aquifer. It intercepts recharge.”
Other factors play into recharge as well, such as seasonal concerns. “If it’s really cold, recharge doesn’t really stop, but you’re usually storing it as snow, above the ground, and then that snow percolates as it melts. That’s some of the most effective recharge,” said Wittman. “Before the plants have started … that water will move through the soil at a slow rate into the deeper part of the aquifer. Sometimes winter is the critical season for recharge. It can be. It really depends on the place.”
Streams too are a part of the aquifer system. “The aquifer is why there are streams when there’s no rain for a month. The aquifers are bleeding into the streams, the streams are fed by the upper part of the aquifer,” said Wittman. “Streams are pumping all the time from the aquifer. Nobody thinks about that.”
Wittman also indicated that a percentage of the water that actually makes it to the aquifer, makes it to the deeper part of the aquifer where municipal wells are typically drilled.
And of course, some water leaves the system through non-natural means. “How much water do we have? does not include the plume of nastiness that you don’t want to use,” said Wittman.
“There’s all sorts of things … you can have high nitrate areas in agricultural settings. No one can really pump that and use it as public supply without extra treatment. You can also get solvents in the industrial areas.” …
“This is not some mystery, it’s the opposite,” said Wittman. “You can solve it using instruments and tools. To do that kind of thing is going to take hundreds of thousands (of dollars) if you’re going to drill new wells; It’s less if you’re using existing wells,” said Wittman. “But the fact is that kind of testing is usually fairly expensive, but it gives you answers that you don’t have to figure out again. You can go forward with that. Once you have it, it doesn’t change that much.”
(Reader, to me Wittman is saying the testing apparatus once installed does not change that much. He is not saying the condition of the aquifer does not change much. Kidston quotes Wittman as saying “not much changes over time. … so once you drill and once you test and once you confirm the results, you can depend on those results for decades … because what you find today will still be true 100 years from now.” See “Ed Kidston says” Bryan Times Aug. 28, 2018. Also see “Resources – Science” for aquifer studies that do show change over time. Also, both Wittman and Feenstra point out that agricultural tiling is reducing the amount of groundwater.)
(Reader see Bryan Times Aug. 25, 2018 under What the Law Says for Wittman’s comments on the legal environment.)
Additionally, he said groundwater is an increasingly utilized commodity. “There are more wells today than there used to be …” said Wittman. “Growth is happening in pumping ground water. The lines from 30 years ago have been going up in groundwater use. That is not unique to this county, not to this state and not to this country. that is happening globally. Everyone is drilling more wells.”
From 1950 to 2010, groundwater withdrawal increased from 175 billion gallons a day to 325 billion gallons a day in the United States, according to the American GeoSciences Institute.
And as the project moves forward and more wells are drilled across the globe, “cone of depression” will likely become an oft-repeated term in the news cycle.
“You create a cone of depression around the well. It’s how the well works. You pump out of the well and the water level in the well itself lowers,” said Wittman. “Because the water in the well is lower to some degree than the aquifer outside of it, the aquifer tries to fill it up, pours in from all sides and the amount and speed that water can move through the aquifer and into the well determines how much you could pump out of the well.”
The cone of depression concept is the one that causes farmers and residential well drillers concern, as the depth, associated geological conditions and proximity to other wells that create a cone of depression, determine whether or not a proximal well’s level will be lowered.
“If the aquifer is really productive maybe no one will notice. If it doesn’t create too much of a cone of depression it won’t affect anyone,” Wittman said of a hypothetical well drilling. “On the other hand, the reason my profession exists is that doesn’t work out all the time.”
A cone of depression’s range depends largely on frequency of well use.