Jet grouting involves drilling a small diameter hole into the soil and then using a high pressure jet of cementitious grout to internally erode the soils as the drill string is withdrawn. This forms a column of mixed soil and grout of variable diameter. We use jet grouting to provide enhanced foundation support or underpinning for structures, improve the performance of weak layers at depth, or to create subsurface cut-off or barrier walls. By installing jet grout columns at spacings where adjacent columns overlap continually over the depth of treatment, a cut-off wall can be formed. This method is ideal for areas with limited accessibility for large equipment, or where the zone of groundwater flow is limited in vertical extent and is located at depth.