A Hybrid Cut-Off Wall at the Dead SeaÂ-Paper

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Arab Potash Company’s solar ponds at the Dead Sea are essential to potash production, but brine leakage from Dyke 1 caused economic losses and threatened dyke stability through erosion, subsidence, and sinkhole formation. The challenge has intensified as the Dead Sea recedes and less-saline groundwater dissolves underlying halite.<br /><br />To reduce seepage and protect the dyke, a cut-off wall up to 31 metres deep was constructed along an initial 4.2-kilometre section. Ground conditions varied between soft, laminated clay and crystalline halite, while dense, highly saline groundwater, high temperatures, and aggressive brine chemistry complicated both excavation and material selection.<br /><br />Salt dissolved rapidly during excavation, and laboratory tests showed that dissolved salt disrupted cement setting in single-phase hardening slurries. The project therefore adopted a two-phase hybrid wall: excavation was supported by a specially developed brine-based fluid, then the trench was backfilled with plastic concrete and fitted with interlocked sheet piles. The support fluid combined salt-resistant clay minerals with polymers selected to withstand different excavation methods and shear conditions. Plastic concrete production also required cooling measures to control temperatures in the extreme heat.<br /><br />Construction sequencing and reliable sheet-pile interlocking were major operational challenges. The team used a runner-and-follower panel method and inclinometer measurements to determine sheet-pile positions and adjust panel widths. This approach minimized custom-made elements and enabled closer spacing of closure panels.<br /><br />The first contract, covering approximately 112,400 square metres of wall, was completed on time in July 2020. Monitoring showed that previously seeping areas became dry, groundwater levels rose upstream toward pond levels, and levels fell downstream after closure panels were completed. These observations demonstrated the wall’s effectiveness and the viability of the hybrid technique in highly saline, geologically unstable conditions.
Keywords
Arab Potash Company
Dead Sea
potash production
brine leakage
cut-off wall
dyke stability
sinkhole formation
plastic concrete
sheet piles
groundwater seepage