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Mitigation actions related to quick-clay slopes often induce undesirable changes to the terrain that may have negative impact on developed areas and local biodiversity. Soil improvement may prevent this. Lime-cement piling causes temporarily reduced slope stability and substantial climate-gas emissions. Less climate-gas emissions are associated to the production of potassium chloride (KCl). KCl improves the post-failure properties of quick clay so it renders not quick and may serve as an alternative to current landslide-mitigation. The mechanisms in this chemical process is well documented, but there exist no installation procedures for KCl wells, nor knowledge on cost/benefit or climate-gas emissions. This paper presents two installation procedures of KCl wells, and studies showing that the climate-gas emissions are far less than installing lime-cement piles. Further development of cost-effective installation procedures is needed to justify application of KCl wells in quick-clay areas.

Retrogressive development of landslides in highly sensitive clays (quick clays) may extend several hundred meters upslope from an initial landslide, and liquified slide-debris may impact buildings or infrastructure in the run-out zone. By installing wells filled with potassium chloride in quick clays, the salt migrates into the surrounding clay and increases its remolded shear strength, reducing its sensitivity. The salt-stabilized, non-quick clay volume may act as a barrier preventing backwards retrogression, thereby contributing to reducing both the area susceptible for being involved in a quick-clay landslide, and the area of the run-out zone. Installation procedures and design guidelines for salt stabilization are examined herein. Installation procedures generating temporary, very small excess pore-water pressures were tested at National GeoTest Site Tiller-Flotten. Although the benefit-to-cost ratios related to these procedures are small compared to conventional landslide mitigation measures, reducing the installation costs to less than 30 USD per m well and increasing the center distance between the wells may justify salt-stabilization as a landslide-mitigation measure. This paper describes experiences from testing safe installation procedures, evaluations of cost-benefit and environmental impact, and proposed design guidelines, introducing potassium chloride as an alternative to conventional landslide mitigation-measures in slopes with highly sensitive quick-clay deposits.