Jack Caldwell - Mining Engineer - Robertson GeoConsultants

One of the enduring mysteries of professional practice is why groundwater experts never apply the Observational Method in their ever-more sophisticated groundwater modeling and monitoring work.

Are they simply unaware of the method? Are they professionally cautious of a method they did not invent? Are they too busy, surrounded by vast numerical models that mean nothing, to apply this approach to groundwater engineering?

It cannot be that they have a better way. It cannot be that they are more skilled at predicting and controlling the future. For they do not have a better way, nor are they more skilled at predicitng the future. All thay have are huge numerical models andtext.

At this link is a detailed exposition of the Observational Methodas applied in geotechnical engineering. On the CD of papers from the recent SME mining conference in Seattle are two magnificent papers on the application of the Observational Method to tunnnelling (see SME’s OneMine, one day for the papers.) Here is the introduction to one of my past writigns on the topic:

The Observational Methodwas first applied by those masters who built cathedrals in the Middle Ages. They did not call the principal by that name, but I suspect they consciously applied it. The first formal enunciation of the method was in the 1940s in the context of soil mechanics; and it has been applied fitfully in geotechnical engineering since. Mining engineers always have and continue even today to apply the method-but mostly unconsciously I suspect.

For those readers not familiar with the Observational Method, it is simple. Analyse what you think will happen using your best estimate of parameters. Then work out what could happen if other, more extreme parameters prevail. Concoct a remedial solution or engineering approach to deal with the extreme parameters. Then start the work. Monitor what happens. If things deviate from your best estimate, as indicated by monitored conditions, implement the appropriate pre-determined course of action. Here is how Ralph B. Peck describes the method:

(a) Exploration sufficient to establish at least the general nature, pattern and properties of the deposits, but not necessarily in detail.

(b) Assessment of the most probable conditions and the most unfavorable conceivable deviations from these conditions. In this assessment geology often plays a major role.

(c) Establishment of the design based on a working hypothesis of behavior anticipated under the most favorable conditions.

(d) Selection of quantities to be observed as construction proceeds and calculation of their anticipated values on the basis of the working hypothesis

(e) Calculation of values of the same quantities under the most unfavorable conditions compatible with the available data concerning the subsurface conditions.

(f) Selection in advance of a course of action or modification of design for every foreseeable significant deviation of the observational findings from those predicted on the basis of the working hypothesis.

(g) Measurement of quantities to be observed and evaluation of actual conditions.

(h) Modification of design to suit actual conditions.

Yet groundwater practitioners persist in ignoring this simple and practical approach. Instead they prefer to tell you to upgrade the calibration of your groundwater model.

Maybe that is all they can do. For they are ultimately devoted to the creed: drill another well, take more measurements. and re-run the model. They never haveto make a decision, act proactively, or take deal directly with the contamination. They are the backroom fellows, the number crunchers, the modellers. No more, no less.

I cannot rest happy with this approach. Hence my appeal and challenge to the groudnwater modeling fraternity: wake up; study the Observational Method; apply it; save us money; and let us march forward to a better way to deal wiht the inevitable groundwater impacts of mining.