1. OVERVIEW OF SEDIMENTARY AQUIFERS Small pores CAPABLE OF FILTERING WATER Complex flow paths through small pores yields LOW FLOW VELOCITIES What does this mean for contaminant transport? Contaminants can be contained and removed

2. KARST DISSOLUTION OF EXPOSED BEDROCK Basic concept: acidic water dissolves rock Water quickly enters ground

3. NATURALLY OCCURING ACIDIC WATER Rain passes through the atmosphere picking up carbon dioxide Soils add more CO 2 Weak carbonic acid solution: H 2 O + CO 2 → H 2 CO 3

4. CALCITE DISSOLUTION Limestone: (CaCO 3 ) Dolomite: CaMg(CO 3 ) 2

5. RESULTS OF KARST DISSOLUTION ‘Aggressive water’ continues to dissolve once underground Water passages enlarged until conduit formation Rapid, subsurface flow via conduits