Management of waste sludge in trench cutting and re-mixing deep wail method

The trench cutting and re-mixing deep wall method (TRD method) is often used for retaining walls, for containment of contaminated soil, etc., because it can create not only vertical diaphragm walls, but also inclined ones of a highly homogeneous quality and without any defects. One of the technical problems encountered with the TRD method involves a substantial amount of waste sludge generated during the construction of such walls. The objective of this report is to determine an effective method to reduce the amount of waste sludge generated to the minimum. Although the simultaneous mixing method has much potential for reducing the volume of waste sludge, when compared to the subsequent mixing met hod, there is risk of cutter restriction by the solidified soil-cement mixture. This is because no additional bentonite slurry is injected into the trench to protect it against a collapse. Methods for evaluating the precise applicability of the simultaneous mixing method are discussed in this paper so as to maximize the potential use of simultaneous mixing method positively and in return minimize the impact to the environment by reducing the waste sludge.