Designer’s Guide When enough is enough


Timothy Allinson, P.E., Murray Co., Long Beach, Calif. I


n recent months, I have been reading a host of arti- cles and getting industry feedback that suggests to me that our industry is in a real state of flux and,


possibly, headed in the wrong direction. Of course, you have to take what you read with a grain of salt, but some of the feedback I have received has been first-hand per- sonal accounts of horrific plumbing installations that just want to make me say, “Enough is enough!” For example, I recently received an email from the


facilities director of a Los Angeles area university com- plaining about his oversized grease interceptor. It seems he read a past article of mine on this subject, and he wanted to know whether there was anything he could do to correct the problems associated with his grease inter- ceptor. Back in 2002, he had a 5,000 gallon unit installed to serve his new dining facility; since then, there have been regular complaints of foul odors. Further, when he has the unit pumped out, it takes 11 days of normal operation for the unit to fill up and start producing effluent to the sewer. He also had a hydrogen sulfide detector installed on the grease interceptor vent,


and it regularly registers high levels of H2S. Clearly, this guy has done his homework. After explaining the grease interceptor UPC Code


changes that occurred in 2006, I told this gentleman that he could replace his 5,000 gallon unit with a 1,500 gal- lon unit. This delighted him, since it would definitely make his maintenance easier and probably resolve, or at least mitigate the odor problems and reduce the likeli-


hood of H2S gas. We are presently working with him to change out his interceptor — a change that should never have been necessary had our Code been stronger in 2002. Shortly after having the email exchange referenced


above, I read about another interesting plumbing devel- opment. It seems that hands free sensor faucets are now considered health hazards; at least that’s what doctors at Johns Hopkins Health Systems have claimed. They shared a study in April that claims that 50% of the water samples taken from 20 sensor faucets contained Legionella, compared with 15% of the samples taken from 20 manual faucets. Further, 26% of the sensor faucets had higher levels of other bacteria, versus 13% of the manual faucets. The manner in which this study was conducted makes


me wonder about its validity. Flow rates, aerators, pipe supply configuration and hardware all need to be taken into consideration when comparing one faucet with another. Since doctors know little about plumbing (except the human kind), the study may have been flawed from a technical standpoint. In fact, other studies have found just the opposite, that manual faucets con- tained more bacteria than sensors. It could be that the problem is associated more with the flow rate of the


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faucet than with its method of operation. Reduced water flows are great for saving water — an important priori- ty — but they are starting to produce unintended conse- quences, and Legionella could be one of those consequences. Aside from not properly flushing Legionella from the


plumbing system, low-flow faucets and their UHE (Ultra High Efficiency) water closet and urinal counter- parts are contributing to dry drains and clogged sewers around the country. Dry drains, for those unfamiliar with the term, are


drain lines that don’t have enough flow to carry solid waste along their length. UHE fixtures are contributing to this phenomenon, since products are changing faster than the industry codes. For example, I have read that a 1.6 gpf toilet has a 45-foot carry distance compared with 29 feet for a 1.28 gpf toilet. In high-rise buildings with limited horizontal pipe (except at the base, where flow rates would be considerably greater), this is not a prob- lem. But in low-rise buildings, with long horizontal runs and limited fixture loading, get ready for blockages. Meanwhile, in some cities, such as San Francisco,


water conservation has reportedly led to municipal sewer odors and blockages. In SF the problem is so bad that they have scripted a $14 million, three-year contract to purchase 27 million pounds of bleach to dump into the city’s sewers. But San Francisco has combined san- itary and storm sewers, so now there is a pending law- suit from the Heal the Bay Foundation for polluting the Bay Area waterways with bleach. I’ll say it again: Enough is enough. Next is the subject of waterless urinals. Again, I am


all in favor of saving water, but I have read test reports and seen photos of pipes that were completely blocked with uric acid crystals after 39 months of use, and this was in glass pipe. One would expect the crystals to col- lect faster in cast iron, due to its rougher wall surface. The same test found that the waterless urinals performed much better when the lavatories were piped upstream of the urinals, which act to flush the urinal drain line, so perhaps that is a necessary code revision where water- less urinals are installed. Another concern about water conservation is the


scald potential associated with low flow showerheads. Many people are trying to do the right thing by putting low flow showerheads on their showers, without con- firming that their shower valve will perform properly at the reduced flow; many won’t, especially older models. In many cases the user would be better off just turning off the shower while they soap up rather than reducing the flow of the showerhead, which increases shower duration and, possibly, creates a scald hazard. The greatest frustration of these water conservation


Continued on page 18 June 2011


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