Setting Personal Standards
During the past year, I’ve had the pleasure of teaching hydraulics to watershapers in a variety of classroom settings. It’s been exciting, believe me, particularly because of the eagerness of the students and their hunger for good information.
These courses, which have been presented under the auspices of Genesis 3, ask a lot of the students who sign up for them. Especially given the tight economy, I find it enormously encouraging that so many people are focused on spending the time and energy required to improve their skills and raise their levels of expertise.
At the same time, unfortunately, my classroom experience has exposed me to some unsavory ways of thinking and leads me to conclude that the watershaping industry hasn’t done a particularly good job through the years in reaching its practitioners with core technical education.
In many cases, the people attending my classes have spent years or even decades in building pools, spas and other watershapes. With distressing consistency, however, they tell me that their education in hydraulics – which is about as fundamental to watershaping as any discipline can be – has almost entirely come to them in the course of listening to sales pitches from suppliers or their representatives.
Frankly, the idea that so many watershapes are being built by people who don’t really understand basic hydraulics other than from product-specific standpoints is quite sobering. By the same token, seeing that so many want to change and grow is most encouraging!
REACTIVE OR PROACTIVE?
Of all the observations I’ve gleaned from my classroom ventures, perhaps the most significant have to do with my growing understanding of the impact codes have on watershapers’ daily lives.
At any given time somewhere in this country, you’ll find small groups of people who participate in writing these codes, which are meant to define standards to be met in all phases of design, engineering and construction. I myself have been involved in such efforts in the past, and I’ve always been interested to observe the agendas (sometimes masked but often quite obvious) of those at the table with me.
Often, for example, there will be someone who wants to devise standards that favor certain types of products or certain common practices – and all too often they will carry the day, if only because their ideas are sharply defined, well packaged and easily adoptable.
The result is, in my opinion, that all too often our standards are either manifestly flawed and plain wrongheaded – or that they fail to reflect optimum conditions in favor of products or practices that dwell on the fringes of acceptability.
Back in November 2008, for example, I wrote my “Currents” column in WaterShapes about codes emerging from the Virginia Graeme Baker Act. If you’ll recall, I described numerous instances of absurdly inadequate, contradictory and in some cases self-serving concepts that had little to do with protecting anyone from suction entrapment. It was a case where flurries of rules were making things worse, not better.
I won’t revisit that swamp here, because there are many other examples that affect every pool and spa built these days. Take, for instance, the six-feet-per-second maximum velocity for suction-side plumbing – a standard set both for safety and hydraulic efficiency. As I see it, standards such as this are not unlike speed limits: They represent allowable maximums, and to exceed them at all involves breaking the law.
So why on earth would anyone ever use the six-feet-per-second threshold as a design standard? I know lots of people do, because I see so many of them in my classrooms. And the thinking apparently has it that the standard is what might be termed “best practice” when in fact it is nothing more than what is minimally acceptable. The problem is, if you use the standard as a design criterion, you essentially leave yourself no leeway, no buffer against “breaking the law.”
I preach instead that you should never aim above a four-and-a-half-feet-per-second velocity on the suction side. With that as my target, I’m comfortable with six feet per second being the minimum standard – and I understand that if I really want to optimize system performance and safety, four-and-a-half feet per second is better.
This gives me the room for variation that comes only from having leeway if I must exceed my own standard. If, for example, the pump I select isn’t exactly optimal for the application and I end up with a velocity of five feet per second, the system will still function well within the limit. If, by contrast, I’ve designed right up against six feet per second, then I’d find myself in violation of the code.
APPLICATION DRIVEN
Here’s another hydraulics-specific example of the thought processes I’m advocating: In my work in the classroom as well as the field, I’m startled to discover how many people think they should select the pump first before developing any other part of a design. In fact, the way you really should work is to make pump selection the last step in developing a circulation system.
This is generally a sign of rote behavior: You pick a one-and-a-half-horsepower pump simply because that’s what you’ve always done – and then you size the plumbing and develop various system features based on the pump’s performance.
It should go the other way around: The first thing you do is establish a flow rate based on turnover, the performance requirements of a desired water effect, the desired flow over a vanishing edge or the constraints of some other form of water-in-transit detail. Thus, you start with the performance need for X gallons per minute, then design your plumbing to handle that flow rate, then calculate the total dynamic head of the plumbing system. Only with the flow rate and head loss numbers in hand should you go about selecting a pump.
Why would you do it in any other sequence? Effectively, this makes the pump selection the driver of the design, which is a case of the tail wagging the dog, big time. Not to offend, but it’s plain silly to think the design should respond to a preselected pump size.
The key here, I tell my students, is to remember that just because we’ve always been told something is true does not make it so.
As another example, I was discussing weirs in one class when a student expressed the belief that the size of the body of water in surface area has an influence on the performance and size of the weir. What this means, I suppose, is that if you have a two-foot-long weir on a 200-square-foot body of water, it is somehow different from a two-foot-long weir you’d place on a two-square-foot body of water.
It wasn’t the first time I’d heard this nonsense, and I felt compelled to explain that, within the surprisingly complex dynamics of water flowing over an edge, the size of the body of water doesn’t really have anything at all to do with it. It doesn’t matter if the weir is on Lake Tahoe or on a bathtub: The size of the body of water is so completely irrelevant to the performance of the weir that it’s not even part of the equation.
When I gently pressed this student on how he came by the information, he acknowledged that it had come from another pool builder who had presumably picked it up from someone else.
This is just one tiny example of the misconceptions that permeate our industry. The sad thing is, these misconceptions often get written into codes, thus reinforcing the flawed thinking and driving people’s practices in a direction in which technical correctness is completely absent.
GROUNDED THINKING
And of course, these issues are not at all limited to hydraulics, with structural engineering being another area where inferior or flat-wrong assumptions manage to find their way into the code books.
In Florida, for example, concerns over groundwater and its ability to pop pool shells out of the ground have led to development of standards for shell thickness – the idea being that the sheer weight of the shell will counteract hydrostatic pressure. Well, that might or might not be the case, depending on site conditions.
A better approach would be to write a requirement that, as part of soils analysis, there should be a determination of the nature of the groundwater and that the structure and other features of the design must be developed with the site’s specific conditions in mind. Such an analysis will tell you whether the situation simply calls for hydrostatic-relief valve – or for the use of a bed of crushed rock and a complete dewatering system.
To think that a one-size-fits-all standard can be devised to deal with something as variable as groundwater is simply absurd, but that’s what has happened in Florida.
I point out to my students that this is just a limited example of a much bigger problem – that is, the widespread belief that swimming pools can be properly designed without a soils report. I’ve run into numerous situations where assumptions about soil conditions are made based on “prior knowledge” of the area – and sure, that might work occasionally, but there is no question that it might also be insufficient and lead to disaster and tens or even hundreds of thousands of dollars’ worth of remedial work.
In an industry that builds concrete structures designed to hold water indefinitely, it defies logic to think you can guess successfully every time and get by without knowing specific soil conditions. Yes, on occasion a report will indicate a course of action that might make the cost so prohibitive that an otherwise good project will be cancelled – but isn’t outright cancellation preferable to months or years of litigation and/or remediation?
Following that line of thought, what’s the harm in exceeding structural recommendations in favor of creating reliable watershapes? I ask this in view of the ongoing debate about compressive strengths of concrete between those who advocate a 2,500 psi standard versus those who support a 4,000 psi standard. As I understand it, the 4,000-psi target results in stronger structures that are less permeable and less subject to the corrosive influence of groundwater wicking into the structure – so why is there any question about which way to go?
It all boils down to this: Do we really have to be told to do something before we do it, even if it’s obviously better? If 2,500 psi concrete is the minimum standard, is there any possible harm in shooting for 4,000 psi?
TAKE CHARGE
My point here is that each of us must set his or her own standard for excellence. In this process, we can be informed by codes and industry benchmarks, but we shouldn’t let observing minimums or hand-me-down practices determine how we work. Instead, we should consciously strive to observe standards we know will create outstanding end products.
As I mentioned above, I’m encouraged that so many people are investing in education – even in these difficult times – and have a clear sense that what they need is good information to help them define their work practices. There is little doubt that, when things turn around, these people will be ready to make the most of the upswing. In fact, if there’s any silver lining in the pressure we’re all under right now, it’s that tough times elevate our appreciation of true value and give us opportunities to recalibrate approaches and critically evaluate common wisdom.
Those of us who base our work on real value will be among the best prepared to meet the demands of clients who want reliable excellence in exchange for their dollars. To exploit these opportunities – which are surely out there – we must first shift our thinking and embrace the idea that we can and should far exceed the least that is expected of us.
Dave Peterson is president of Watershape Consulting of San Diego, Calif. He’s been part of the watershaping industry since 1994, starting his own firm in 2004 after stints with an aquatic-engineering firm and a manufacturer. A registered civil engineer, he now supports other watershape professionals worldwide with design, engineering and construction-management services and may be reached via his web site, www.watershapeconsulting.com.