calcite precipitation

[Hailey]

Hello,

We have an aquifer with high calcium and bicarbonate values (avg. calcium ~420 mg/L, avg. bicarbonate 600 mg/L) but the pH is neutral (around 7). We calculated saturation indices with PHREEQC and found calcite to be supersaturated, indicating it might precipitate from solution. But doesn't calcite only precipitate out under alkaline pH? i.e. 8-10? Or am I missing something.

Any help is appreciated. Thanks