Jet grouting is used as a “targeted” and selective treatment for certain soil layers and can therefore, for example, “fill” karst anomalies or provide deep treatment of soft layers of soil lying under thick, compact strata. In some special cases, it is also used to mitigate liquefaction risk within a soil. Finally, the drilling machines used are small enough to work within buildings, to underpin existing structures and to operate in areas that are difficult to access.