Backflow Best Practices and Standard Details: Part 2

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Randy Holland

Premise Isolation Backflow Prevention: Best Practices & Standard Details Part 2

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Part 3: Placement Practices

Premise Isolation Backflow Prevention: Best Practices & Standard Details

http://www.safe-t-cover.com/

Premise Isolation: Best Practices & Standard Details

….Definitions and term use:

Isolation backflow prevention: In addition to the lavatory and water fountain, most buildings’ plumbing systems include fixtures that are designed to clean contaminated equipment, carbonate beverages, and even infuse chemicals and detergents. Many of these processes create dangerous and toxic substances. If these substances were allowed to reverse back into the building’s fresh water piping, an event known as backflow, it would create serious health hazards for the individuals on site. Building authorities deal with these risks by specifying appropriate backflow preventer assemblies at those specific locations where contamination is a risk. The term for this solution is “isolation backflow prevention” because a special plumbing apparatus known as a backflow preventer isolates high-hazard fixtures and equipment at the point of use from the rest of the on-site piping system.

….Definitions and term use:

Containment or ‘Premise Isolation’ backflow prevention: For public water systems, water that has been delivered through its water meter to a water customer is only done safely and responsibly when there is no possibility that that water will return back from the customer to the water system, an event (also) known as backflow. Disparate groups within plumbing, design, and water management have devised their own favorite terms for this system. The plumbing community prefers “Containment backflow prevention” because such systems contain delivered water at the subscriber’s premises; On the other hand, water districts tend to prefer “Premise Isolation”. It is important to understand that whether called Containment or Premise Isolation, we are referring to the task of eliminating backflow at the Point of Supply from the public water system.

This presentation is limited to the recognized best practices of these containment or premise isolation systems.


http://blog.safe-t-cover.com/blog/containment-vs-isolation-the-backflow-preventer-installation-battle

IntroductionThe water engineering community has been struggling with new professional liability risk involving the location of premise isolation backflow preventer systems; Not because of new design practices, but because of new information about the old practices. There has been a slow trickle of warnings for years, but in the past 3 years important organizations and industry leaders have added new warnings with much stronger language that not only change recognized best practices, but actually challenge the fitness and safety of older placement methods altogether.


http://www.awwa.org/

http://fccchr.usc.edu/

https://www.aspe.org/

IntroductionCan we rid ourselves of the problem by dumping the system itself?

Sadly, we are learning through SCADA and AMI that there is actually more backflow occurring at the premise than we previously suspected.


IntroductionAnd with this new risk realization comes a new interested party: The insurance company. Because of this very public commentary from experts and leading groups, casualty carriers, through subrogation, have new weapons for damage recovery. And anytime the accused designer is able to demonstrate that local government contributed, whether materially or passively, to the poor design, the water district and/or building authority may be at risk for the liability.


Assuming the legal rights of a person for whom expenses or a debt has been paid. Typically, an insurance company which pays its insured client for injuries and losses then sues the party which the injured person contends caused the damages to him/her.

Introduction

Because of subrogation, the water district needs to demonstrate that no unsafe methods are promoted by their plans review teams. The best way to demonstrate that is with published standard details and drawings that are consistent with recognized best practices.


Introduction…Meanwhile, at the 2016-17 bi-annual conference of the American Society of Plumbing Engineers, one popular learning module titled “Let the Civil Engineer Deal with the Containment Backflow System” suggests that leadership is seeking reassignment of the premise isolation backflow system design to the civil discipline. No surprise, other than how long it took to realize… Plumbing engineers have nothing to gain and everything to lose when they specify indoor RPZs because

• The flood risks now being realized from indoor installations of RPZs is extraordinary;

• Designing for outdoor placement includes grading and surface contouring for sudden flood water flows; a task that is beyond the scope of a plumbing engineer’s training or expertise.


http://blog.safe-t-cover.com/blog/the-dragon-in-the-basement-backflow-prevention-flood-risks

IntroductionAccording to a survey of 1220 U.S. civil and plumbing engineers conducted over a 19 month period, 3 out of 4 say ‐they need local water authorities to provide standard details for outdoor aboveground backflow preventer systems.You can read more about the results of this survey here.


http://blog.safe-t-cover.com/blog/backflow-preventer-installation-survey-results-from-1200-engineers



• Water Districts NEED Premise Isolation in order to fulfill their EPA mandate; and

IntroductionBottom Line:

“…. The return of any water to the public water system after the water has been used for any purpose on the customer’s premises or within the customer’s piping system is unacceptable and opposed by AWWA.…”

• Premise-Isolation design details and specifications need to be provided to civil engineers because of their general familiarity with standard details and their comparable lack of familiarity with backflow systems.

AWWA’s preamble to the Cross Connection Control Manual, published by EPA


1. Water utilities are seeking more premise-isolation.

2. That more containment systems are being specified as RPZ regardless of hazard threshold.

3. AWWA, ASPE, & the legal community recognize “outside aboveground” as ‘best practice’ for premise isolation.

This presentation will show…Introduction


Above ground in an enclosure Inside a building Inside a vault

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Placement Practices3 options for backflow preventer placement


http://blog.safe-t-cover.com/blog/7-reasons-for-aboveground-backflow-installation-in-backflow-preventer-enclosures

Inside a vault

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A subterranean vault would have to be considered the legacy method still widely practiced among designers today but as most of you know, an RPZ can never be installed below grade . Beyond the issue of being unsuitable for RPZs however, there are compelling reasons to discontinue the use of vaults altogether.


Placement Practices

We’ve all seen the extraordinary measures OSHA imposes to legally access vaults for maintenance tasks. fresh air exchange hoses, tents, extra men. The costs are more and more prohibitive but frankly, the risk of serious injury is real as well. But beyond the cost of safety for onsite workers, liability issues persist.

Inside a vault3 options for backflow preventer placement

1. Safety


Placement Practices

When a vault floods like this one, the mandatory test cocks are submerged, and in that event, a violation of the International Plumbing Code has already occurred. Consider what would typically make up the constituents of that water. Runoff of lawn chemicals alone make this a clear and present danger to the water supply.


2. Liability


Placement Practices

In fact, it led the USC Foundation of Cross Connection & Hydraulic Research in 2005 to change their recommendation of even double check BFP installation in vaults.

“The foundation’s recommendation would be to install the double check valve above grade.”

- USC-FCCHR “Crosstalk, Summer 2005


2. Liability


http://fccchr.usc.edu/_downloads/Cross%20Talk%20Archives/2005.23.2.pdf


Placement Practices

The foundation added stronger language 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….”

- USC-FCCHR “Crosstalk, Summer 2014 .

2. Liability Inside a vault

3 options for backflow preventer placement




Placement Practices

Buildings, through their normal life of changing tenants over time, change uses with respect to hazard levels, and hazard levels, or more precisely, the named high-hazard threshold, has become a moving target.


3. Changing Demands


Placement Practices

Around the corner from our Nashville office, I snapped this picture. It sits in front of a warehouse owned by an automotive dealer. When they bought the property and erected the building, they put a double-check BFP down in that vault with the meter.


3. Changing Demands


Placement Practices

A few years later, the city changed an ordinance that redefined their particular use to high-hazard. 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 of it. They easily paid 3X the necessary cost because they began with a “DC-only” solution. Designers need to contemplate these latter-day retrofits as they make design decisions.


3. Changing Demands



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If the double check valve is commonly installed in a vault, then equally common is that the RPZ is installed in an indoor location.


Inside a building

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1. Space allocation/Accessibility

The space provided for an indoor BPA is routinely inadequate as provided by the architect. That’s because giving up space that would otherwise add value is being allocated as non-revenue space. Non-revenue space is the enemy of every development project.


Inside a building

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The BPA pictured cost tens of thousands in property value. Even a mere 3” indoor BPA will cost a developer $6,000 to $9,000 more than an outdoor installation in a heated enclosure. A separate presentation discusses the real costs of indoor backflow preventer installation in detail.

1. Space allocation/Accessibility


http://blog.safe-t-cover.com/blog/indoor-backflow-preventer-installation-means-lost-revenue

Inside a building

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2. Professional liability: indoor flooding

Here’s what the American Society of Plumbing Engineers advise about indoor RPZs.“Before an RPZ is located, consideration should be given to both how much water will be discharged, and where it will drain. Consideration must be given to the drain system to assure the drainage system can handle the load. If a drain is not capable of accepting the flow, other choices as to the location of the valve, such as outside in a heated enclosure, should be made.”

-2006 ASPE Plumbing Engineering Design Handbook, vol 2, p 70


Inside a building

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This flood occurred in a hospital mechanical room causing over $1M in damage.



As we have illustrated, an RPZ, behaving as designed, creates a sudden flood.

http://blog.safe-t-cover.com/blog/rpz-backflows-a-flood-risk-valve-manufacturers-must-think-so





Inside a building

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This is two sides of 1 wall. On the left, we see that the sudden water flow and volume moved the wall into the next room (right photo), which happened to be a telephone and low-voltage wiring room.



Inside a building

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The insurer sought recovery from all the risk holders including the engineer, architect, contractor, subcontractor, and even the most recent recorded tester;



Inside a building

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While the details of who paid what were not made public, we do know that the property insurer was made whole by one or more of the listed defendants.



Inside a building

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In times past, this event would have been seen as an unforeseeable casualty, a pipe burst. But insurers have been listening to the next part of the discussion. This commentary from experts changed everything.



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Inside a building


So if an RPZ is designed to dump water, then drain capacity is the issue. The chart on the right is from the manufacturer of the BPA seen in the previous flood photos. It illustrates the anticipated flow rate from the relief valve at various pipe sizes and at various pressures. Here is a link to the this chart for Watts devices. Note that the assembly shown will flow 375 GPM at 85 PSI. A 4” drain pipe with a 1% fall rate evacuates clean water at a maximum rate of 93 GPM. If that device is flowing at 375 GPM and your clearing 93, then you are flooding at a rate of 282 GPM.



http://media.wattswater.com/ES-RVD.pdf

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Inside a building


An article published June 2013 in the Chicago chapter of the American Society of Plumbing Engineers written by David DeBord, a former president of that organization, and current Education chair of the national ASPE, states all these facts better than I can.



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Inside a building


He uses the Manufacturer’s data supplied by a different manufacturer, and he uses a 65 PSI instead of my 85, but he actually does the math in the article and offers FLOOD rates or 219 GPM for 2 1/2 and 3”; and flood rate of 482 GPM for 4” and above.



Backflow Failure

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Placement Practices Inside a building

3 options for backflow preventer placement

Watch this video showing a check valve failure and the resulting flood water flow.



https://www.youtube.com/watch?v=d7MjJuZQoYo

https://www.youtube.com/watch?v=d7MjJuZQoYo


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Above ground in an enclosure

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In 1996, the American Society of Sanitary Engineers (ASSE) developed a quality and safety standard for aboveground enclosures as a product class. It’s known as ASSE-1060 and it addresses 5 concerns. • Freeze protection to −30° • Vertical load strength of 100 PSF,• Full flow drainage capacity, etc.• Reliable Access• Keyed Security

1. Quality, 2. Safety, 3. Security


http://blog.safe-t-cover.com/blog/the-5-major-asse-1060-reqs-for-backflow-covers





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Moreover, they took the guidance further by identifying all possible climate conditions and defining appropriate guidance for Freeze-prone areas (Class I); Frost-only areas (Class II); and warm areas where no climate control of any kind is required (Class III).

1. Quality, 2. Safety, 3. Security


http://blog.safe-t-cover.com/blog/which-class-backflow-enclosure-do-you-need






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“An outdoor, aboveground BFP 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 criteria in ASSE’s Standard-1060 to protect these installations. It’s a win-win-win ‘insurance policy’.

Douglas Cregor, Esq.

4. Legal endorsement


Indianapolis attorney, Doug Cregor has been the leading attorney in the U.S. specializing in cross-connection control litigation and advocacy. He is quoted in Plumbing Standards Magazine as follows…

The public water supply is unprotected from returning water without a premise isolation system. RPZs are only fail-safe solution.

The duties of the building/plumbing authority and the plumbing code do not wholly satisfy the duties of the water utility.

Indoor RPZs 3” and larger are perpetual floods risks.

The need to address sudden on-site water flows disqualify MEPs from outdoor premise isolation design, even if within MEP halo.

Civil engineers are unfamiliar with BPA installations and need standard details from water authorities.

Take-Aways

A broadly adopted region-wide set of guidelines would save cities 000s of hours in plans-review time.


Safe-T-Cover's blog: Updated weekly with articles on backflow prevention, standard details, and best practices.

Enclosure Design eBook: Learn the 5 design considerations for aboveground enclosures

Recent story on decision to add standard details by the city of Arlington, Texas

Trends in Backflow Preventer Installation: A downloadable guide to the latest trends in backflow best practices.

Additional Resources


http://blog.safe-t-cover.com/blog

http://offers.safe-t-cover.com/a-project-engineers-handbook-5-custom-enclosure-design-considerations?__hstc=57789173.013bbfac08ca4c20d1aed2be0da7d93a.1468961942820.1482327809599.1482328445135.16&__hssc=57789173.1.1482421413842&__hsfp=1471637596&hsCtaTracking=da4c57c1-164b-481c-8119-27db2d1a4a73%7C5f220379-07d5-427f-9454-5670d433f6ad

http://offers.safe-t-cover.com/a-project-engineers-handbook-5-custom-enclosure-design-considerations?__hstc=57789173.013bbfac08ca4c20d1aed2be0da7d93a.1468961942820.1482327809599.1482328445135.16&__hssc=57789173.1.1482421413842&__hsfp=1471637596&hsCtaTracking=da4c57c1-164b-481c-8119-27db2d1a4a73%7C5f220379-07d5-427f-9454-5670d433f6ad

http://www.arlington-tx.gov/water/arlington-rolls-out-new-engineering-details/

http://www.arlington-tx.gov/water/arlington-rolls-out-new-engineering-details/

Thank You!Premise Isolation: Best Practices & Standard Details


Backflow Best Practices and Standard Details: Part 2

Engineering

Transcript of Backflow Best Practices and Standard Details: Part 2