Fig. 1.

Acidity (mg L−1) for the Upper Freeport sites, best-fit first-order decay function (k = 0.0273), upper and lower confidence intervals, and, when adjusted so that mean cumulative difference = 0 (k = 0.0395), extrapolated to the year 2050. Horizontal dashed line represents the cutoff acidity to begin passive treatment (100 mg L−1). CAD, cumulative average difference; LCL, lower confidence limit; UCL, upper confidence limit.

 


Fig. 2.

Percent error for 2006 predicted acidity as a function of actual acidity in 2006 for Upper Freeport sites.

 


Fig. 3.

Acidity (mg L−1) for the seven Pittsburgh sites, best-fit first-order decay function (k = 0.0.0426), and upper and lower confidence intervals. Horizontal dashed line represents the cutoff acidity to begin passive treatment (100 mg L−1). LCL, lower confidence limit; UCL, upper confidence limit.

 


Fig. 4.

Acidity (mg L−1) at the T&T site for the first 11 yr after closure, best-fit first-order decay function (k = 0.1125), and upper and lower confidence intervals. Horizontal dashed line represents the cutoff acidity to begin passive treatment (100 mg L−1). LCL, lower confidence limit; UCL, upper confidence limit.