By Jack Caldwell - Mining Engineer - Robertson GeoConsultants

This is a story of a time before computers; before groundwater conceptual models, numerical models, baseline models, and predictive models; before groundwater model calibration, verification, or sensitivity analysis. This is a story of a time when there was no such thing as a professional geohydrologist, hydrogeologists, or groundwater modeller.

In those distant times, we still believed that we had to solve engineering problems in mining and groundwater using analytical methods, coupled with a good dose of engineering insight and judgement.

The story: Archaeological evidence indicates that some forty-thousand years ago there was mining of hematite at Bomvu Ridge in Swaziland. Some forty years ago I went to the ridge to see the open pit of the “new” mine. The pit was dug deep into the highly fractured bedrock of ancient geology—Precambrian at its youngest.

I went with Professor Jennings because my master’s thesis was the explanation of fluid flow in fractured bedrock. Professor Jennings was there to find a way to steepen the slopes of the pit, the stability of which was bedevilled by persistent groundwater pressures.

I solved the problem of fluid flow in fractured rocks. Professor Jennings solved the problem of water pressure in the slopes by recommending a tunnel deep beneath the slopes to drain the groundwater. I got my master’s degree. The miners dug the tunnel and it worked; the pit proceeded ever deeper with steep slopes.

Intelligence, understanding, insight, and judgment were our tools.

Today we would have to assemble a big, expensive computer groundwater model using finite elements. We would have to write long reports justifying a calibrated conceptual model. We would have to run predictive simulations and so on and so forth. And maybe we would still come to the same conclusions or maybe we would get stuck in the glories of modelling.

My point is that any model is just that: a model. It is an aid to judgment. It expands thinking. It may even justify prejudice. But is can never substitute for engineering insight, foresight, skill, intuition, or judgment. A model, analytical, numerical, or any of the infinite variety of today’s names, can never make a decision, pinpoint a course of action to solve a problem, or shown the boldness of a genius, like Professor Jennings.

This is my tribute to him. My tribute to those old engineers who did great things in the absence of expensive computer models; who did not moan about mean clients or the complexity of reality; but who marched forward armed only with knowledge, skill, and imagination.