Chiang Mai Journal of Science

Rapid industrial and commercial expansion in recent years has created the need for more land. One of the options to create more land is to reclaim ex-mining land. Ex-mining land contains numerous mined out lakes and ponds. Numerous methods are available to fill these lakes and ponds. The ex-mining land consists of variety of materials inclusive of sand, clay, slime and organic peat as well.  A new landfill method which is economically competitive, technologically feasible and which will not contribute to any environmental problems was developed. It is based on flocculation of slurry slime with Natural Organic Polymer (NOP) or Poly Vinyl Acetate (PVA), mixed with residual soil and use the flocculated slurry slime as part of the fill material. The physical and geotechnical properties of the flocculated slurry were assessed by laboratory tests, including pH and Eh measurements, acid neutralization capacity (ANC) determination, hydraulic conductivity and comparison and cost analysis with conventional fill materials such as sands. The flocculated slurry slime was slightly alkaline, with pH 8.4, Eh value 171 mV, negligible ANC, and hydraulic conductivity was 8´10^–5 to 7´10^–4 m/s. It was also found that the material is unlikely to cause significant change in the redox condition of the subsurface environment over a long-term period. Proposed method is more feasible as compared to other methods in comparison and cost analysis. In general, the flocculated slurry slime is suitable to be used as a fill material for land reclamation.