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Borehole grouting commands attention at NGWA Ground Water Expo and Annual Meeting

Borehole grouting commands attention at NGWA Ground Water Expo and Annual Meeting

A landmark study on grouting water wells and geothermal boreholes, and a school on geothermal drilling mud and grouting were spotlighted at the National Ground Water Association Expo and Annual Meeting today and Wednesday.

On Wednesday, NGWREF William A. McEllhiney Distinguished Lecturer Tom Christopherson kicked off his 2011 lecture, “The Nebraska Grout Task Force Research: Unexpected Results — New Solutions.” Christopherson is with the Water Well Standards and Contractors’ Licensing Program for Nebraska’s Department of Health and Human Services.

Today, NGWA began its Geothermal Drilling Mud and Grouting School with an orientation and presentation on safety to be followed Friday by hands-on training at an outdoor demonstration site.

Both programs emphasized that grouting boreholes works in protecting groundwater quality provided the type of grouting fits the conditions and is applied properly.

The Nebraska grout study began in 2000 with installation of a prototype well using clear PVC casing to allow use of a down-the-hole camera to visually inspect the grout seal. Upon reviewing data in 2000, the state expanded the study to multiple sites in varying geologic and hydrologic conditions to get a broader spectrum of data.

Christopherson said he was surprised at the number of cracks and voids that were discovered using a visual inspection. The study also dye-tested the test wells with fluorescent dye to get additional data on the effectiveness of the grout seals.

While there are many conclusions that can be derived from the study, he said one is that “just because grout is cracked doesn’t mean it’s bad.” Sometimes cracks in the grout or detachment of the grout from the casing would allow a flowpath for water down the annular space only to be stopped by the seal further down the well.

“Hydrologic conditions play a big part,” said Christopherson, as do the grout particle size, moisture content, and other variables. He said much can be learned from the study that will help water well contractors properly apply the right grout based on the specific conditions.
The study was a joint project of DHHS, the Nebraska Well Drillers Association, the Nebraska Conservation and Survey Division, Baroid, Cetco, Wyo-Ben Drilling Products, and Design Water Technologies.

During the Geothermal Drilling Mud and Grouting School, both new NGWA President Art Becker, MGWD, and NGWA Director John Pitz, CPI, emphasized the importance of precision in drilling geothermal boreholes for the installation of loop tubes and optimization of the system performance.

Pitz said geothermal drillers require some but not all of the skills and competencies needed by water well system contractors. He said NGWA examined both sets of skills and competencies to come up with requirements for its new certification, the Certified Vertical Closed Loop Driller.


 NGWA, a nonprofit organization composed of 13,000 U.S. and international groundwater professionals — contractors, equipment manufacturers, suppliers, scientists, and engineers — is dedicated to advancing groundwater knowledge. NGWA’s vision is to be the leading groundwater association that advocates the responsible development, management, and use of water.

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