Instrumented Packers at TVA's Boone Dam-PPT Presentation

PPT Presentation

Pdf Summary

The Tennessee Valley Authority’s Additional Drilling and Grouting Program (ADGP) at Boone Dam followed an initial program focused on treating shallow epikarst and rock. Its purpose was to treat groutable defects below the cutoff wall and complete a two-line high-mobility grouting curtain, with holes spaced no more than 20 feet apart down to elevation 1,150.<br /><br />Unlike the initial program, the ADGP used instrumented packers for all injections, typically cased boreholes to 10 feet above the cutoff-wall design bottom, reduced grouting pressures above that level, and placed grouting under TVA’s direct control.<br /><br />Instrumented packers measured pressure downhole, helping operators control injection pressures more accurately than relying on calculated effective pressure. Their sensors were configured to measure external pressure during water-pressure testing and grouting. Calibration and field observations were part of the evaluation.<br /><br />The ADGP results indicated little concern about erosion below the cutoff wall. There were no significant grout takes during installation of the multipoint sampling probes, water-pressure tests showed low Lugeon values, and 98% of grout takes were classified as low. The packers operated reliably, with no significant problems involving connection loss, data transmission, or instrument damage.<br /><br />Further data are needed to understand differences between instrumented-packer readings and the previously used calculated effective pressures. Possible influences include formation pressure and whether injections occur under low- or high-flow conditions.

Keywords

Tennessee Valley Authority

Boone Dam

Additional Drilling and Grouting Program

ADGP

instrumented packers

grouting curtain

cutoff wall

Lugeon values

downhole pressure

groutable defects