ABSTRACT
Assessment of the water balance is an essential step in the design of any municipal solid, industrial or mine waste storage facility. The water balance calculation enables the designer to estimate the quantities of water entering, retained within and exiting the waste body (e.g., Fenn, et al., 1975, Blight, 2010 and others). The inputs to the landfill or other waste storage facility usually consist of the water content of the incoming waste and the rainfall infiltration for the site, and the outputs are evaporation from the surface and leachate or seepage exiting from the base of the deposit. Estimation of the inputs and the output evaporation enables the quantity of leachate or seepage to be predicted. This in turn allows the need for an impervious underliner, to prevent ground-water contamination, to be assessed as well as the quantities of leachate or seepage for which the drainage or seepage effluent treatment system need to be designed. Fluctuating water storage within the waste body bridges between inputs and outputs and completes the water balance. At closure of the storage facility, the water balance needs to be reassessed for post-closure conditions to decide on the need for ongoing leachate collection, storage and treatment and to design the post-closure facilities. Recently, Henken-Mellies and Schweizer, (2011) have emphasized the ongoing importance of water balance estimation in all phases of the life-cycles of waste storage facilities.
