The secant bored pile wall at the A12 Hackney to M11 Link Road used alternate 'hard' reinforced concrete piles and 'soft' cement-bentonite piles. A sprayed concrete facing was employed over the facing of the soft piles because of concerns about their permeability. This report describes performance monitoring of the hard-soft piling system at the site. Piezometers were installed in the retained ground, the soft pile itself, and the ground beneath the new carriageway so that the flow of ground water could be clearly established in the vicinity of the wall. These measuremens were supported by laboratory and in situ tests to establish the permeability of the retained ground and the soft piles. The results from the field monitoring were compared with finite element predictions of the pattern of water seepage in the vicinity of the wall. (A)

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