Water control for a rock-soil interface - infrastructure at a contaminated site

Abstract

Abstract The conceptual model of the rock-soil f(and future shaft) interface was confirmed (so far not rejected) using data from investigation boreholes. The location of a depression in rock (a likely deformation zone) was indicated and confirmed using borehole data. Wave-washed deposits (upper part of the stratigraphy) and a lower water-bearing strata (soil) coinciding with the depression are key water-bearing features in soil. The likely deformation zone is expected to be a key water-bearing feature in rock. Grouting design (curtain-and blanket grouting) and sealing of soil (jet-grouting and sheet-pile walls) focus on sealing these features. The wells (infiltration) that are planned between the shaft and a contaminated site may, if needed, further reduce the effect of the construction on hydraulic head and flow. Changes that are of interest since they may also influence the mobility of a contamination. A low grouting pressure is used in rock adapting to a shallow depth (curtain grouting) and a possible horizontal connectivity. The steps of the observational method, as described by Peck (1969), were found very useful. Its focus on “the general nature, pattern and properties” and “a working hypothesis of behaviour” is of particular interest, highlighting the understanding of the system at hand.