The Atlas Geotechnical crew is privileged to work all over the world, collaborating with squared-away engineers of varied backgrounds and sharing stories that range from tall tales to practical advice.
I’ve learned that every community includes at least a little folklore in how they design and build. Always there is some inexplicable local practice, unique to the area and unknown elsewhere, that designers, regulators, and builders all assert is necessary to project success.
A fairy tale is created when the lesson learned from a real experience, over time, becomes disassociated with its context and starts being applied to all projects. What started as sound practice turns into a guiding fable that, more often than not, just adds cost and difficulty without any benefit.
As an example: “House your family in the sturdiest structure you can afford” becomes, over time, “don’t build a house out of straw because a wolf will come and huff and puff and blow it down.” Practical advice. Brick houses are better against wolf-blowing and also generally. But if all you have is straw, and you’re a professional engineer, maybe your best course of action is to engineer a wolf-proof straw bunker.
Vibratory Pile Hammers: On Oahu in the early 1980’s a contractor was extracting timber piles from the sand backfill of a closed wharf, some of which were near the sheetpile quaywall. A few interlocks had separated below the waterline. Of course vibrating the sand flows it out the defective interlocks. Subsidence broke the wharf; it was a legitimate problem. Instead of learning to inspect interlocks before extracting waterfront piles, the Owner invented a myth that vibratory hammers are dangerous and shall not be used. Henceforth all piles, including sheetpiles, are driven with impact hammers. Far far away from the water, on different islands, specifications prohibit vibratory hammers. This Owner is influential; engineers accept that vibratory hammers are dangerous and ban them from all of their projects, not just their wharf projects. It would be a charming superstition if it weren’t so costly. Vibratory hammers have been proscribed for nearly 30 years. The engineer who made the rule nears retirement. It may take another 30 years for the fable to fade into distant memory and for Engineering once again to prevail in Honolulu.
Scarify and Recompact: In San Diego and parts of southern California, all earthwork begins (after stripping) by removing 6″ of soil, moisture conditioning, and rolling it back down as fill. Maybe at a few sites this upper soil might have been compressible, in which case for heaven’s sake perform remedial grading and make it suitable. But blindly converting 6″ of competent semi-formational flat ground into fill just increases your fill thickness. It is equally effective as stepping over the sidewalk cracks while walking home from school. Upon arriving you find that your mother’s back is, in fact, not broken. Maybe your superstition works; maybe you just walked home funny.
Detensioning Tiebacks: At this year’s Spring Seminar in Seattle an engineer asked a panel of experts “why does the City require detensioning tiebacks?” Two panelists offered straightforward answers: (1) “that started before I took over administering the rules,” and (2) “yeah, we’ve been trying to get that requirement dropped for years now, despite running full-scale demonstrations.” One senior community member shared a story from the ’80’s about a bar tieback that got broken and jumped part-way out of its hole. A close call, sure, but how does that experience relate to strand tiebacks with heads confined by a cast basement wall? Folklore. An irrelevant cautionary tale, pure and simple. That community has recognized it and, over time, will dispel the local myth that tieback strands are unreasonably dangerous.
So here’s the question: What folklore have you incorporated into your practice? I promise you there’s some nugget of superstition in your reports and designs that your peers in other regions would struggle to understand. Do you test micropiles using an ASTM setup instead of PTI? Do you insist that only your techs are capable of performing quality assurance testing? Require 6″ of compacted crushed rock beneath footings even in dry weather?
I don’t advocate that we expunge all local traditions from our work. Consider, though, examining your practices, understanding the origins of your folklore, and retaining just the beneficial parts. The practice of engineering evolves constantly through the work of our whole community. The generational shift currently in process is our opportunity to improve our practices and better serve our communities.