Hot Bitumen Grouting at the Avery Island Salt Mine-Paper

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The Avery Island Salt Mine experienced a major groundwater inflow at its 700-foot level in 2011. Water and sediment entered through changing pathways in the salt formation, creating a surface depression and at times reaching very high flow rates. Four phases of surface cement grouting over the following years reduced the inflow intermittently, but results were not stable; cement grout was often carried into the mine by the moving water.<br /><br />In 2020, the project team supplemented cement grouting with hot bitumen injection. Three boreholes with short hydraulic connection times to the mine inflow were selected for bitumen, while five holes with longer connection times were used for cement-based grout. Heated bitumen was injected at approximately 400–480°F. As it cooled, it thickened and adhered within the flow channels; cement grout was also used to cool and reinforce the bitumen. The work required specially designed heated storage and piping systems, careful supply planning, and extensive safety procedures.<br /><br />Over six months, approximately 278,000 gallons of hot bitumen and 108,000 gallons of cement grout were injected. The inflow typically responded soon after injection began, and larger bitumen batches produced the most lasting reductions. Less than 10 gallons of bitumen was detected in the mine outflow, in contrast to cement grout, which continued to wash out. The final injection event reduced the inflow from about 75 gallons per minute to approximately 20 gallons per minute.<br /><br />The treatment did not completely seal the inflow, but the reduction was considered successful and more durable than earlier results. The project demonstrates that hot bitumen can help control difficult, high-flow groundwater pathways when conventional grouting alone is ineffective.

Keywords

Avery Island Salt Mine

groundwater inflow

hot bitumen injection

cement grouting

surface depression

salt formation

mine water control

hydraulic connection

inflow reduction

grouting project