Abstract: A method for producing graphic or mathematical boundary information, in the form of graphs and the like, and the use of such information, for more accurately predicting the acidity and alkalinity of water drainage from rock types which may be subjected to weathering conditions in earth moving operations.Selected rock samples of particular rock types collected from a geographic location of interest are subjected to oxidation and leaching for a predetermined period of time to simulate natural weathering conditions to which the rock types may be exposed. The leachates from each rock sample are chemically analyzed by titration with standard acid and base solutions to selected end points to obtain their acidity or alkalinity concentrations, and these concentrations are differentiated for the particular rock sample to obtain a net acidity or alkalinity value for the rock sample.