6 ways to improve backflow preventer design

Life is better above ground! Even some inanimate objects are better above-ground like automobiles, weather balloons, and containment backflow preventers. Yes, backflow preventers. Not that you can prove it by the normal way of things. Here in the U.S., it is common to find a containment backflow preventer design, whether for a fire or domestic line, specified for a below-ground vault. But there are myriad reasons to join a growing consensus of municipalities that have pulled the plug and drained the pit. Living with this perpetual hazard to life, limb, and water safety just doesn’t make sense. If you find yourself clinging to this old-school favorite, nostalgia won’t bail you out. Here are six reasons to climb that ladder one last time.

1. No RPZs in Vaults

First and foremost, reduced pressure zone valve assemblies (RPZs) can never be installed below grade. Forget the complexity of the Kentucky Plumbing Code(s) and how to interpret them. There is no need to consult the code on this particular issue because every manufacturer of USC[i] and ASSE[ii]-approved RPZs in the U.S. prohibits installation of this assembly below grade. No RPZs in vaults.

But what about double check valve assemblies (DCs)? Why not continue to install DCs in vaults? I’ve got six more reasons!

We’ve all seen the extraordinary measures the Occupational Safety and Health Administration (OSHA) imposes to legally access vaults for maintenance tasks (Figure 1). By now, we are familiar with fresh air exchange hoses, tents, and extra men, but as of August 2015, there are new regulations that are even more onerous. A new permit system is now in place for entry into hazardous or potentially hazardous spaces for which most water vaults are included. The permit requires several administrative items to be named or declared including names of entrant, assistant, and supervisor, the purpose of the entry, the time required for entry, the work done, the emergency services standing by in the event of an emergency, and so on. Anymore, there is no way to open one of these things with less than a 4-figure expenditure.

Vault Maintenance
Figure 1

2. Confined Space Hazards: Injuries

Yes, confined space hazards make this approach financially constraining, but that’s because of the underlying truth: the risk of serious injury in vaults is real. OSHA claims that there are 4.8 million entries with over 11,000 injuries each year. According to data collected by the U.S. Department of Labor, fatal injuries in confined spaces average 92 per year.

3. Flooded Vaults Violate the IPC and UPC

Beyond the cost of protecting onsite workers, there are even more significant problems with the use of vaults. According to the USC Foundation of Cross Connection Control & Hydraulic Research (USC), flooded vaults violate the International Plumbing Code. When a vault floods (Fig

Flooded Vault
Figure 2

ure 2), the mandatory test cocks are submerged. The water may look clean, but consider what would typically make up the constituents of that water. Run-off of lawn chemicals alone makes this a clear and present danger to the water supply.[iii] In fact, it led USC in 2005 to change their recommendation of DC installations stating, “The foundation’s recommendation is to install the double check valve above grade.” Nine years later, USC continued to express this position with even more specificity in 2014: ”When a backflow preventer is installed below grade, the vault or pit in which an assembly is installed may fill up with water. The water in the pit could create a cross-connection between the water in the pit and the backflow preventer through the test cocks. This may occur whether the test cocks are opened or closed….”


4. Firefighter Safety

Fire line backflow preventer enclosure
Figure 3


Until recently, double check detector assemblies for large fire systems were commonly placed in vaults or inside the building. But more and more fire departments across the country are demanding that fire line resources be available to firefighters at the street as far away from the fire as possible. And even more interesting, some of the coldest cities like Chicago, Buffalo, and Rochester are requiring that where possible, these resources are to be installed in an aboveground heated enclosure. After all, where is the wisdom in placing access or control of these resources on the side of a building, or worse, inside a building? Occasionally, firefighters must interface with the backflow preventer itself. Why send firefighters into subterranean vaults in the middle of the night in freezing conditions? Entering a building or a vault is an additional hazard that can and should be avoided. Aboveground fire line backflow preventers with accompanying Fire Department Connections (FDCs) move all the water resources where access and safety are maximized (Figure 3). Chicago, IL, Flower Mound TX, Lynchburg VA, Charlotte, NC are just a few of the many cities that now require outdoor aboveground fire line BPAs on commercial fire lines where distance can improve firefighter safety.

5. Retrofits of Backflow Preventer Design

RPZ retrofit
Figure 4

Water-use hazard-thresholds are changing. Either by tenant changes over time, or mandated guideline changes by the purveyor. First consider tenant changes. Buildings, through their normal life of changing tenants over time, often change to higher hazard water uses. A flower shop becomes an urgent care facility. A shipping warehouse becomes a paint shop or a plating facility. Changing tenancies are not the only way that hazards change. Cities and counties are also changing what they regard as high hazard. Figure 4 shows a recent example involving a Nashville property. When an automotive dealer bought this property and erected the building, they put a double-check BPA down in the vault with the meter. This was consistent with the then-current guidelines. A few years later, the city changed an ordinance that redefined their particular use to high-hazard. To be clear, the automotive dealer did not change what they were doing, but rather, the city decided that what they were doing was high hazard after all. When they sought a permit to upgrade the HVAC system, the city forced them to change to an RPZ. So after constructing this huge vault, they now leave it almost empty with an RPZ in an enclosure perched on top. They easily paid three times for a single solution simply because they began with a vault. As time goes on and these retrofits become more common – either because tenants change or because municipalities tighten their high hazard thresholds – the underground vault will be properly regarded as the best way to waste money by digging an expensive hole that holds nothing.

6. Legal Community Endorsement

In these litigious times it is worthwhile to contemplate what the legal community has to say about best practices for containment BPA placement. Until his death three years ago, Attorney, Doug Cregor, specialized in cross-connection control litigation and advocacy and was a recognized leader in this area of the law.

“An outdoor, aboveground BPA installation may be the best way to 1) reduce the owner’s exposure to damage caused by flooding and the corresponding water contamination caused by a cross-connection; and 2) reduce the legal liability of the design engineers, the installers, and the certified testers whose professional actions, in part, may have otherwise caused the flooding harm. The water industry has a nationally accepted design criterion in ASSE’s Standard-1060 to protect these installations. It’s a win-win-win ‘insurance policy’.”

– Plumbing Standards Magazine, Summer Issue, 2009

As Cregor mentioned in the above quote, there is a guiding specification that municipalities can adopt to ensure quality and safety in the application of aboveground enclosures for water systems, and it should be seen as today’s remedy for the vault. ASSE standard 1060 was created in 1996 and amended in 2006 in order to create uniform safety and quality guidance for enclosure manufacturers. In fact, IPC code: 608.14.1 states, “Outdoor enclosures for backflow prevention devices shall comply with ASSE-1060”. It specifies minimum standards for heat, security, strength, drainage, and accessibility and cities that have added guidance for these installations commonly cite this standard as essential.

Aligning with recognized best practices is one of the most important ways to demonstrate wise stewardship to your leaders and stakeholders. Ignoring these practices demonstrates the opposite. If you are uncomfortable with the idea that the vault’s days are numbered, remember that there was a day when the last wagon wheel rolled off the assembly line. Let’s not wait until a sickness or death in one of our great cities or towns leads back to a contaminated vault. If you’re saying, “That’s the way we’ve always done it,” be careful. Your boss may decide that the next

[i] USC-FFCCCHR – University of Southern California Foundation of Cross Connection Control and Hydraulic Research. This organization certifies all backflow preventer assemblies (BPAs) for quality and reliability through an exhaustive review and testing process over multiple years. The International Plumbing Code (Tennessee’s guidance) requires that all BPAs bear the USC certification.
[ii] ASSE – American Society of Sanitary Engineers. ASSE International maintains nearly 50 product performance standards, ranging from double check and reduced pressure backflow preventers to dielectric pipe unions, with many more in the development stages. ASSE’s product standards are minimum performance requirements for component parts of the plumbing system. The Kentucky State Plumbing Code and the International Plumbing Code (Tennessee’s guidance) require ASSE certification of all BPAs.
[iii] USC-FCCCHR made assertions in 2005 and 2014 about perpetual cross connection hazards present in all backflow preventers. These assertions force invocation of IPC 608.1: “A potable water supply shall be designed, installed and maintained in such a manner so as to prevent contamination from nonpotable liquids, solids, or gases being introduced into the potable water supply through cross-connections…”

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