Wednesday, December 26, 2018

Simple solutions

Source of story and image.  Hat-tip Lucas Machias

I love five cent solutions to million dollar problems.

West Virginia determined that dumping loads of limestone "sand" on the banks of streams is a cost effective way to address low pH (acid) streams.

West Virginia suffers from the double whammy of being downwind of the coal-fired power generation plants that carpet the Ohio River valley, thus getting a significant amount of acid rain. They also have mine tailings that are rich in sulphides that, in turn, leach acids and heavy metals into streams as rain percolates through them.

Many researchers developed schemes to inject carbonates into streams to neutralize them. That requires power, maintenance and significant investment.

The West Virginia approach leans heavily on the fact that the pH drops when it rains. The acid falls out of the sky. The acid increases as it percolates through the tailings.

The stream rises after it rains.

Ergo, dump a big pile of the buffer (limestone or dolomite) on the bank of the stream.

Failing that, dump it in one of the big ditches where runoff will wash some of the finely ground limestone into the stream.

The problem, a surge in low pH water, fixes the problem.

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