Redevelopment of Old Sludge Reservoirs

Because of environmental and societal constraints Tessenderlo Chemie at Ham is reorganizing its sludge deposit sites, covering more than 200 ha in the area. Due to changing production and organization, some of the deposits are being closed and the sites redeveloped, whereas other deposits are reorganized. This paper deals with the problems, occurring at the treatment and reuse of the specific industrial sludge as a construction material for dikes.The geotechnical characteristics of the sludge were investigated, and a test dike with a height of 18 m above original ground level was constructed. The applicability of naturally dried sludge, of sludge with forced natural drying, and of sludge dried by filter pressing was tested. The appropriate construction pace and maximum elevation were determined, based on hydrostatic settlement measurements, oedometer tests, vane and direct shear tests as well as borehole shear tests. Computer simulations were calibrated with the field measurements, and used to evaluate the stability and safety of newly constructed sludge embankments.