Applications, Observations, and Lessons Learned from Remedial LMG Grouting-PPT Presentation

PPT Presentation

Pdf Summary

The Boone Dam Internal Erosion Remediation Project used low-mobility grouting (LMG) as an interim risk-reduction measure and to gather information about subsurface conditions. The dam’s foundation includes limestone, soils, and a 20–40-foot-thick epikarst zone, where voids and soil-filled features can create paths for seepage and grout loss. The LMG program ran from December 2015 to February 2017 and formed part of a composite seepage barrier, alongside high-mobility grouting and a cutoff wall.<br /><br />A test program evaluated grout mixes, injection criteria, monitoring methods, and grout behavior in the ground. The work included 533 LMG holes across two lines, initially spaced at 10 feet and then split-spaced. Most grout used a stiff, 0–2-inch-slump mix; a more fluid mix was used selectively for void filling. Grout takes generally decreased with successive rounds of drilling and grouting. Post-treatment tests also showed substantially lower water flow than initial testing.<br /><br />Key lessons included the importance of thorough exploration, detailed logging, and strong data management. These investments provided information that supported later project decisions. Grout mix design is especially important in karst conditions: changes in slump require corresponding changes to refusal criteria. The team also found that Doppler flow meters were difficult to calibrate at low flow rates with stiff grout, while a pump-stroke calculator proved more efficient.

Keywords

Boone Dam

internal erosion

low-mobility grouting

LMG

karst conditions

epikarst zone

seepage barrier

grout mix design

water flow reduction

grouting monitoring