Water Board tests for stress on aquifer
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Allison Gatlin
01/26/2012 |
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Water check: Tony Schrader, of the U.S. Geological Survey, checks flow rates in an old El Dorado Chemical Co. well. A crew from the USGS is checking the well to determine recovery rates on the Sparta Aquifer
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Despite a few technical skips and bumps in the road, the Union County Water Conservation Board began on Tuesday the third aquifer stress test in the last century in an effort to determine how well the Sparta Aquifer responds to the stress of continuous pumping.
For seven days straight the UCWCB, partnered with the U.S. Geological Survey, the Arkansas Natural Resources Commission and the Arkansas Geological Survey, will draw about 460 gallons per minute from the aquifer, mirroring tests conducted in 1947 and 1999, explained Tony Schrader, a hydrologist with the USGS, to members of the water board, who met Wednesday.
"We look at the man-made drawdown in the pumping and then we look at the natural recovery after we turn the well off," he said. "So we bracket the response to give how well the water flows through the aquifer, which is essential for how much you can get in supply and storage."
During the second phase of the test, researchers will measure how quickly the Sparta responds by comparing water levels within four wells on El Dorado Chemical property, he said. In the past, two of the wells were used for simple observational purposes and two for pumping.
Pumping in the latter two ceased in the 1980s, an employee with El Dorado Chemical added.
Due to partnership with the three state and federal agencies, the typically $18,000 to $20,000 test won.t cost Union County taxpayers a dime, said Sherrel Johnson, UCWCB grants manager.
More than a day after the pumping from the aquifer began, Schrader noted some drawdown in water levels in the four wells between 6 inches and 1 foot, with the exception of Well 6B, which has already dropped down 1.5 feet, echoing the last test in which that specific well dropped a total 4.5 feet.
The process has been a cumbersome one so far, Schrader said, explaining that the start date had to be pushed back to account for
a piece of equipment that shipped late. Since then, a leak has developed in the pumping equipment, data from monitoring equipment at Well 6B hasn.t been able to be downloaded and thunderstorms have made manual monitoring impossible, he said.
Another instrument should ship tomorrow and be installed by Monday, at the latest, to record the recovery, at the very least, he added.
Historically, numbers from the pair of tests in the 1940s and 1990s have been comparable, Schrader said.
"They were almost identical," he added. "It showed what would be considered a very good or high quality flow rate within a sand aquifer and storage was average or above normal of what you would expect in that type of aquifer."
Tests in nearby areas in the last 15 years, as well as the past two tests in Union County, have also indicated that there is no sedimentation within the aquifer, which Schrader explained as cementing of sand grains, which cuts down on how well water can flow within the aquifer and how much water can be contained.
In other news:
- The board approved amendments to monitoring cost contracts with the Union County Conservation District and Burns and McDonnell Engineering Company, Inc., for $15,000 and $6,000, respectively. The contracts will run through April of this year.
- Tom Burger, of Union Power Partners, reported that an instrument used to measure pH in the water at the plant was discovered on Jan. 10 to be faulty and had been recording pH levels at a full point higher than what they actually were. The plant has already taken corrective measures by doing daily checks in two places to verify that levels are increasing to the 7.8 level at which they should be maintained.
- Ginger Risinger, a hydrology technician with the UCCD, told the board that measurements for automated data logger (ADL) wells were complete by the first of the month and that the quarterly well measurements for the winter will be complete by March.
- Of the quarterly measurements, a few wells dropped in Calhoun and Ouachita counties, however, Union County's wells were either the same or had increased in water levels, she said.
- For Columbia County, not enough wells have been measured to determine an increase or decrease, she added.
- Risinger also introduced her new field assistant, Phillis Young, who joined her Wednesday to take measurements of the wells being monitored throughout the aquifer test.
- Johnson reported that she would be traveling to today's meeting of the Louisiana Sparta Aquifer Ground Water Commission to thank commissioners for agreeing to pay a quarter of the cost of monitoring 28 wells established in 2002 as a method of monitoring the Sparta's response to recovery efforts.
Due to the fact that seven of the wells are located in Louisiana, the UCWCB's counterpart was only asked to pay 25 percent of the total cost at $35,370.
On Jan 27, 2012, at 3:57 PM, James C Petersen wrote:
©El Dorado News-Times 2012
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