Case Study: Slope Stabilization using Deep Soil Mix (DSM) Columns – Strategic Petroleum Reserve, Bayou Choctaw Facility-PPT Presentation

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The Strategic Petroleum Reserve and U.S. Department of Energy sought a repair for cracking and slope movement on the main access road to a storage facility in Louisiana. The site lies beside Cavern Lake, associated with a salt cavern drilled in 1942 that collapsed in 1954. Soil borings, cone penetration tests, surveys, and slope-stability analyses indicated both shallow and deep failure concerns.<br /><br />Conventional options—including lowering the road, a riprap berm, sheet piles, and a pinned bank—were constrained by the road and underground utilities, limited right-of-way, unsafe or unavailable land-based crane access, cost, and the risk that vibration or soil displacement could worsen instability. Deep soil mix (DSM) panels were selected as a potential way to improve the slope’s factor of safety using land-based equipment, though constructability remained a key concern.<br /><br />Construction planning accounted for tight access, crane loads, lake levels, and the possibility of triggering bank movement. Quality controls included daily oversight of DSM installation, twice-daily sampling to check mix strength, daily lake-level monitoring, and remote inclinometer readings two to four times per day. Inclinometers tracked movement during and after construction.<br /><br />Monitoring recorded total surface movement exceeding 20 inches. DSM installation itself was associated with lateral movement of up to 5 inches at a depth of 60 feet; one inclinometer became unreadable before the project was completed. In July 2021, the client reported a new slope-failure crack and requested a site assessment. The case-study text does not provide the assessment’s findings or the final performance outcome.

Keywords

Strategic Petroleum Reserve

Department of Energy

Louisiana

deep soil mixing

slope stability

road repair

lateral movement

inclinometer monitoring

soil borings

Cavern Lake