Abstract:
The Avery Island Salt Mine has been in production for over 120 years. In December 2011, an inflow of groundwater increased at the 700-foot level of the mine and caused unraveling of the soils above the infiltration to create a depression in the topography. The area was named the T27 inflow. Several companies were mobilized to the project location and an extensive cement grouting program was employed to successfully mitigate the inflow to an acceptable level. Since 2011, several grouting programs have been employed to combat the inflow. Each program produced a measured impact on the T27 inflow, however the results varied with time and the client desired a more stable solution. In 2019 a hot bitumen injection program was designed and developed based on the project site conditions. Access to the site is challenging and injection depth to access the flow channel is in excess of 400 feet, thus the injection method, material delivery, storage, logistics and personnel safety were all thoroughly vetted during the design and development process. Targeted holes with short connection times to the inflow point were chosen as injection points for the hot bitumen material while holes with longer connection times were used for cementitious grout injection. Hot bitumen injection began in May of 2020 and several sessions of injection were implemented over the subsequent 6 months during the height of the COVID pandemic and amongst several hurricanes and tropical storms which ravaged the area. A continuous supply of hot bitumen material was not available locally, thus the material was injected in batches of 20, 000 to 50, 000 gallons at each session. In all, around 250, 000 gallons of hot bitumen and cementitious grout material was injected over the 6-month period. The T27 inflow was impacted with each injection session with the final session reducing the inflow to an acceptable level. Targeted holes for injection have been exhausted and drilling of the area is currently ongoing to further define the flow regime for future injection efforts. Hot bitumen injection is seldom utilized in the grouting industry, however, has proven to be an effective method for mitigation of water inflow in unique circumstances. This paper will discuss the bitumen grouting program utilized and the impact on the T27 inflow.