Extremely brackish water found in Wolfforth ETHP well

EDITOR'S NOTE -- This is the last article in a series designed to update readers on the status of the Edwards-Trinity (High Plains) Aquifer drilled in Wolfforth--CEM.

By Jason Coleman, P.E.
HPWD General Manager

In the first two articles of this series, we described the geophysical logging and construction of the test well at Wolfforth.  The results of the pump test and water quality test are presented in this concluding article of the series.

After the temporary well was constructed in the Edwards-Trinity (High Plains) (ETHP) aquifer, the contractor used an airlift procedure to help remove the drilling mud and develop the well.  It is necessary to remove the cake of mud in the borehole wall so that the formation water is transmitted to the well casing.  The contractor then installed a submersible pump for test pumping the well.  Over a twelve hour period of test pumping, the well did not produce much more than ten gallons per minute.  As a result, the test pump was removed in favor of additional well development techniques.  These processes involved more air lifting, as well as a chemical treatment to help remove any remaining drilling mud.  Despite these efforts, little improvement in the well productivity was realized.  Our conclusion is that the limestone rocks do not contain significant cracks or void spaces at this location.

The formation water produced during test pumping was also tested at this time.  The results of this analysis show very high dissolved mineral content.  The water was tested by hand sampler in the field, at a certified laboratory, and with a continuous monitoring probe.  All three methods produced very similar results.  You may recall that public drinking water systems must have total dissolved solids (TDS) of less than five hundred milligrams per liter.  A TDS of 500 mg/L is roughly the same as conductivity of 810 microsiemens per centimeter (uS/cm). 

The chart shown on the front page of this electronic newsletter indicates the test well conductivity ranges from 8,000-16,000 uS/cm, much higher than the allowable for public drinking water.

Scientific publications indicate that water quality in the ETHP Aquifer is generally a bit higher in TDS than Ogallala.  However at this location, the ETHP results are more than ten times higher in TDS than the Ogallala.  This leads us to question whether the sampled water is truly indicative of the ETHP, or if there is a Dockum Aquifer influence in the sampled water.  HPWD studies show that water quality of this same TDS level is present in the Dockum Aquifer.  We also know that “upconing” may occur in the Dockum, which could result in the high TDS results from these samples.  More work should be performed in the ETHP water quality sampling before we may conclusively resolve this question.

City of Wolfforth to drill new municipal water supply well

Drilling will soon begin on a new municipal water supply well in Wolfforth, which will also be used to investigate the Edwards-Trinity (High Plains) and Dockum Aquifers in western Lubbock County.

Texas based Layne Christensen Company will begin drilling the well early next week. The entire project is expected to be completed in two weeks.

The City of Wolfforth is exploring possible use of groundwater in the Edwards-Trinity (High Plains) Aquifer for municipal use. This aquifer lies directly beneath the Ogallala, which is the primary aquifer on the Southern High Plains.

A small diameter test hole will be drilled through the Edwards-Trinity (High Plains) and Dockum aquifers to a depth of approximately 1,700 feet. The U.S. Geological Survey (USGS) will then log the entire borehole using advanced technological methods.  The information from this survey provides very detailed analysis of the formations, including water quality.  After the logging is complete, the Dockum Aquifer portion of the test hole will be plugged to the base of the Edwards-Trinity (High Plains) Aquifer, which is about 300 feet below land surface.

If adequate water is located and can be produced from the Edwards-Trinity (High Plains) aquifer, the test hole will be reamed, cased and completed for use as a municipal well to increase the City of Wolfforth’s current groundwater supply. If this effort proves successful, it will be less costly than pumping water from the city’s other water rights which are located southwest of Wolfforth.

City of Wolfforth officials are working to ensure citizens have a reliable source of clean drinking water for years to come. The recently completed electro-dialysis reversal (EDR) treatment plant addresses this need.  This state-of-the-art water treatment plant went online in May 2017 and is currently serving approximately 4,600 citizens.  Officials are hopeful this test well project will increase the city’s current water supply.

The High Plains Underground Water Conservation District (HPWD) Board of Directors unanimously agreed to cost-share this exploratory well with the City of Wolfforth in early 2017. The HPWD Board agreed to allocate $90,000 to assist with the project, plus USGS logging costs.

 “The Edwards-Trinity Aquifer will hopefully provide us with a water source that will not compete with our own wells or the irrigation wells in the area,” said Wolfforth City Manager Darrell Newsom. “Our partnership with HPWD will allow us to share information with other cities in the region, and that will help all of us. HPWD’s cooperation and support will allow us to obtain much more complete data than we would be able to obtain and understand on our own.”

This is the District’s third partnership with a municipality to explore the Dockum Aquifer. In 2016, the cities of Abernathy and Lubbock, with assistance from the HPWD, drilled test wells to determine the quality and quantity of the brackish aquifer. Lubbock’s test well, located near the South Water Treatment Plant, was completed in December 2016.

“We are learning more about the Dockum Aquifer as a result of these efforts,” said HPWD General Manager Jason Coleman. “In recent years, the District has established a monitoring network in this aquifer, and these partnerships allow us to add additional data collection sites.”