ACCUMULATION OF WATER AND GENERATION OF LEACHATE IN A YOUNG LANDFILL

Seven-year-old pilot-scale landfills were investigated with respect to operation of the soil cover, accumulation of water and rainfall-leach ate Bur relationship. The annual soil moisture fluctuation in the soil cover was of the order of 120 mm. Given an average precipitation of 5 80 mm, the net water input into the landfill, split into storage and l eachate discharge, was on average 250 mm annually. The portion that be comes leachate increased from zero to about half during 6.5 years. The storage increase was about 180 mm/m during this period. Fair agreemen t between the calculated storage and the moisture content in solid was te samples was observed, A 1-2 month time lag in the net water input-l eachate discharge relation was observed. It is suggested that the obse rved short leachate flux response to a period of infiltration may indi cate that a large part of the water is retained by surface tension as thin films in restricted channels, which is overcome by gravity when t he input is suddenly increased. The storage-leachate flux relationship was quantified and was found to consist of a family of curves dependi ng on the storage and the rise or decline of leachate flux. (C) 1997 E lsevier Science B.V.