Reuse of Dredge Material as a Liner in Landfills

Abstract

AbstractWaste disposal is an important issue for human societies. Landfill sites are widely used for the disposal, treatment and management of waste materials. Leakage of leachate from landfills results in the pollution of the local environment, contamination of soil and groundwater. The risks of leachate generation and leakage can be mitigated by proper design of engineered landfill sites that use impermeable clay liners. Parvathy Puthanar, the highly polluted canal in Trivandrum, Kerala, India, is under cleaning. Its dredge material disposed on the roadsides is a major issue to the authorities and public. Attempts are under way to reuse the dredge material. In this study, the characteristics of the dredge material and its suitability as a clay liner were studied. The dredge material is classified as poorly graded sand with a permeability of 1.18 × 10–2 cm/s, making it unsuitable as a liner. So, the optimum percentage of bentonite required to be added to obtain a clay liner was found out by conducting laboratory studies. The optimum bentonite percentage of 30–40% was obtained based on percentage fines, permeability, plasticity index and UCC value. A water content of 2% above OMC based on placement water content can be used for the preparation of clay liner. A geosynthetic clay liner (GCL) was also developed with this modified dredge material by adding 40% of bentonite. The GCL section proposed consists of modified dredge material bonded by 2 mm geosynthetic at the ends. The developed compacted clay liner (CCL) gave a permeability value of 6.7 × 10–7 cm/s while the GCL gave 6.34 × 10–9 cm/s, thus the GCL developed is more efficient in preventing the permeation of leachate.KeywordsDredge materialClay linerBentoniteCompacted clay linerGeosynthetic clay liner