Groundwater Remediation -
http://www.geo-solutions.com/construction-technologies/Soil-Bentonite-Slurry-Walls.php - The SB slurry wall is typically excavated with a long reach excavator under a bentonite water slurry. The slurry stabilizes the excavation and allows it to proceed to practically any depth, even well below the water table. Long reach excavators designed for slurry trenching are capable of depths up to around 90 ft (26 m).