Vertical Barriers/Slurry Walls Bio-Polymer Trenches Permeable Reactive Barriers Soil Mixing Jet Grouting Wetlands Site Remediation Dam Grouting MGP Sites Levee/Dam Reinforcement & Repair

Excavation/Structural Support

Kingston, TN: Cold-Joint Mitigation by Jet Grouting, Kingston Ash Recovery Project, Perimeter Wall Stabilization


Jet Grouting is currently being used as part of the Kingston Ash Recovery Project as a means to mitigate potential cold joints in the Cement-Bentonite Perimeter Wall. Any intersection in the wall that occurs after the initial wall segment has been in place for 14-days or longer is considered a cold joint. Cold joint locations are considered to be at higher risk for failure and therefore require specific measures to mitigate this possibility. Jet grouting was chosen as the method for the required mitigation. By installing a pair of "keyways" at each location, spanning the cold joint and tying the two panels together, the potential for failure can be eliminated.

A test program was completed to demonstrate and evaluate the column spacing, injection pressure, lift rate, rotation rate and overall means and methods. The test program included flushing the grout from a fresh jet grout location and pumping the water out to visually confirm the geometry of the column.

Each cold joint location is being pre-drilled using 12-inch air rotary methods. The completed boring is then tested for verticality using a gyro-scope-based down-hole survey instrument to ensure and document each pre-drill location is within the established tolerance of 1% of vertical.


Jet Grouting is accomplished with Geo-Con's Cassagrande C-7 track-mounted jet grout rig. A Portland cement and bentonite grout is prepared in Geo-Con's 5-cubic yard batch plant and injected at high pressure, from the bottom up, using a controlled lift and rotation rate. Variable geometry is being created by varying the lift rate and rotation rate to create the "keyway" which consists of alternating 14-inch to 12-inch column sections.

The grout is designed to attain a minimum of 315psi at 28-days of cure.

A fully documented quality control program is being implemented including:

  • Drill Rod verticality and pre-drill reports
  • Down-hole verticality confirmation testing and reporting
  • Jet grouting reports
  • Grab sample collection and testing - A series of grab samples of the fresh jet grout return is collected approximately every 4 columns. Grabs from 5 depths are collected, molded, cured and tested for Unconfined Compressive Strength at 7, 14, and 28 days.

It is anticipated that the PWS installation could generate over 200 cold joint locations that will require mitigation.


Corporate Headquarters: 1250 Fifth Avenue • New Kensington, PA 15068 • 724-335-7273

© 2014