Karstic and Water Stop Grouting, Jefferson Co., MO

Project Introduction

REN was requested to provide a drilling and grouting plan to stop water outflow from a private impoundment. The 44’ tall dam was constructed on top of rock with an appropriate clay core and key way. However it was discovered that a vertical limestone joint passed through the spillway. Further investigation of the joint discovered the joint to be filled with Karstic Residual soil and highly weathered rock.

Key Highlights

• The vertical joint resulted in 18’ tool drop in the spillway.
• The vertical seam was excavated and filled with medium mobility low permeability grout.
• Traditional cement rock grouting techniques were utilized below the keyway and for the dam.
• Nearly 600 yards of ready mix grout was used to reduce costs for the large voids in the spillway.
• Around 430 cu ft of Portland cement grout was used for the traditional grouting program.
• To find the bottom of the karstic feature in the spillway an excavation 47’ x 65’ long was required.

Conclusion

REN’s targeted excavation and grouting program successfully treated the vertical limestone joint and underlying karstic voids, restoring the integrity of the private dam and spillway. By combining medium-mobility grout in large voids with traditional rock grouting techniques, the team provided a cost-effective, long-term solution to control seepage and protect the structure.