Aspe nat'l convention let civildsncontmtsys slideshare

Randy Holland, MBA Best Practices & Public Policy Consultant

Let the Civil Designer Deal with the Containment Backflow System

Backflow Prevention: 2 doctrines

Introduction

Isolation: Plumbing code enforcement•asserts that ‘we can take care of any cross connection contamination risks by enforcing the plumbing code’. Simple as that.

Containment: Protection against unknown changes•Argues no, that’s not good enough because of unknown changes to individual plumbing systems after the C of O is issued.

The 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.

Introduction

Can 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.

Introduction

And 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.

Introduction

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

Bottom 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

Introduction

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

1. Design differences DC vs. RPZ; Why it matters

2. Current placement practices and the problems with each

3. The real flood risks of indoor RPZs?

4. The real cost of indoor containment?

5. The explosive growth of the RPZ and how it impacts M/P Es

6. What are the “Best practice” examples around the U.S. for containment BPAs?

7. How do we encourage transitioning this task to the civil engineering discipline?

Today We’ll Cover…

Let the Civil Designer Deal with Containment System

2 types of backflow Preventers:

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Double-Check Valve Assemble, DC or DCDA

Reduced Pressure Zone Valve Assembly, RP RPDA

A designer may specify one of two types of BFPs for premise isolation. Up until recently, the decision for which assembly to specify was based solely on the perceived hazard to the waste water system created by the processes of the end user. High hazard (better named, high waste-hazard) uses were required to utilize an RPZ. Uses that did not pose a risk to the waste water were allowed to use a DC.

1. Design Differences (and why it matters)

2 types of backflow Preventers:

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Double-Check Valve Assemble, DC or DCDA

Reduced Pressure Zone Valve Assembly, RP RPDA

For example, a medical facility or a chemical plant triggered the requirement for an RPZ while an office or simple retail user would be allowed to use a DC or, depending on the municipality, no premise isolation system at all.

Now, as we will discuss below, many purveyors are requiring RPZs on all premise isolation systems because of the inherent limits of protection provided by the double check valve for the public water supply.


DC: Low hazard?

Public (Supply)

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PZ The Double-check assembly was developed in the 1950s for the fire industry. And for many years it was regarded as a satisfactory solution. The design is simple. Any time system-water pressure on the property (private) side exceeds the system pressure on the city (public) side, two redundant check valves close and water stops flowing backwards.


DC: Low hazard?

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PZ But no remedy exists in the event of a malfunction of the valve closures or if debris in the water line causes the valves to not close completely. Additionally, The DC is a closed, or blind system making detection of any failure impossible without a field test performed by a licensed tester. Today, millions of DCs are in service that may have failed. When a Florida city began its annual testing program in 2010, it found 52% of the valves in service had failed with no way to determine how long they had been inoperable.

Public (Supply)

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RPZ: Fail-safe against returning water

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Public (Supply)

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The RPZ emerged in the 1970s as a remedy to the double-check limitations. Like the DC, it incorporates 2 redundant check valves. But unlike the DC, the RPZ incorporates a hydraulically operated differential relief valve directly beneath the # 1 check valve. It is this relief valve’s placement (along with the universal laws of hydraulics) that make this a fail-safe solution for water purveyors. As elegant as the design is, it comes at a cost. And that cost is the surrounding area.


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Flow

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As the DC reveals, valves fail. But when they fail in an RPZ, the assembly is designed to create a deluge event directly under the assembly so that no contaminated water returns to the public water supply. Because of the danger of contamination, no water from the relief valve may be piped directly from the assembly. It must release into the atmosphere away from any piping. Watch this short video revealing an actual discharge.


Flow Stop

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In a flow-stop situation the water between the check valves will often drain out the relief valve. Some think that that event defines the limit of what water can ever flow into a drain.

Not so.


Loss of pressure

#2 valve blocked#2 valve blocked

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PZ Consider a flow-stop situation, one that might naturally occur at the end of the day. If you look closely, you can see that a small pebble has lodged in the #2 check valve. Now let’s say there’s a fire around the corner that causes back siphon at this point in the system.

Because the # 2 check valve is not closing, all the water that has been delivered to the building will continue to flow out the relief valve until the private lines are cleared. If this is a four story building, that’s a lot of water!



#1 valve Failure

#1 valve Failure

Normal delivery pressure

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PZ Now consider a failure of the #1 check valve. Under normal operating conditions, this failure would go unnoticed. After all, water is being called for by the user through the opening of taps. The water flows in undeterred.

But with this imbalance in the system, changes in demand tend to rock the remaining valves open and closed sporadically.


Demand


#1 valve Failure

#1 valve Failure

Blockage relief valve

Blockage relief valve

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Demand


This creates the conditions for the “perfect storm” scenario. The imbalance created by the # 1 failure makes the relief valve more prone to opening momentarily, allowing debris to block the closure of that valve.

Under such conditions, a constant flow of delivered water will begin to flow directly out the relief valve. This reduces water pressure for the user, but delivery will continue.


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No demand



The real damage begins when the user stops using water such as at the end of a work day.

With the relief valve blocked open and the # 1 valve inoperative, all the water that the purveyor can provide will flow unabated out the relief valve wherever it might be, and continue until the water source is interrupted.

This is the scenario that must be avoided: the perfect storm.


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This picture was tweeted last summer by a Nashville backflow tester. He was called to a multi-story office building on a Sunday to inspect a “malfunctioning backflow preventer”. By the time he completed his service of the assembly, a small pebble was all he recovered from the 8” RPZ in the background.


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This was the scene when he arrived.

By the way, the RPZ was working perfectly before and after the call, behaving precisely as it was designed to.


Above ground in an enclosure Inside a building Inside a vault

3 options for backflow preventer placement

2. Placement Practices

Inside a vault3 options for backflow preventer placement

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.


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.


1. Safety


When a vault floods like this one, the mandatory test cocks are submerged, and in that event, a violation of the International Plumbing 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


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


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



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


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


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




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 building3 options for backflow preventer placement

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.



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.

1. Space allocation/Accessibility



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



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

We’ll cover these risks more deeply below.



Above ground in an enclosure 3 options for backflow preventer placement

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



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).




This widely accepted standard simplifies the specification process for designers. By naming ASSE-1060 and the appropriate class, there will be no surprises upon delivery.




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…

4. Legal endorsement

Douglas Cregor, Esq.



““An outdoor, aboveground BFP installation may be the An outdoor, aboveground BFP installation may be the best way to best way to 1) reduce the owner1) reduce the owner’s exposure to damage caused by ’s exposure to damage caused by flooding and the corresponding water contamination flooding and the corresponding water contamination caused by a cross-connection; and caused by a cross-connection; and 2) reduce the legal liability of the design engineers, the 2) reduce the legal liability of the design engineers, the installers, and the certified testers whose professional installers, and the certified testers whose professional actions, in part, may have otherwise caused the flooding actions, in part, may have otherwise caused the flooding harm. The water industry has a nationally accepted harm. The water industry has a nationally accepted design criteria in ASSEdesign criteria in ASSE’s Standard-1060 to protect these ’s Standard-1060 to protect these installations. It’s a win-win-win ‘insurance policy’.installations. It’s a win-win-win ‘insurance policy’.

Douglas Cregor, Esq.

4. Legal endorsement


Inside a building

3. The Real Flood Risks of indoor RPZs


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



You are looking at 2 sides of one 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.




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




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.




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.




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. 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.




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.


3 .The Real Flood Risks of indoor RPZs


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.




He concludes that regarding indoor RPZs…



Backflow Failure


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



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

2. Indoor RPZs Reduce the rentable square footage of a building reducing revenue & property value

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.

4. The Real Cost of Indoor BPAs

Charlotte: 32.000 SF

Columbus: 36.000 SF

Suffolk Cty: 33.333 SF

Arlington: 32.000 SF

Average: 33.325 SF

Consider the average square footage required for just a 3-inch indoor in-line backflow preventer. To the right, four representative cities are represented. The average required space is 33.325 SF.

Assuming a discount rate of 9%, rent value of $30 per foot annually, and a 25 year life, the net present value of that space to the property owner is $12, 156.48.

Arlington, TX: 32 SF


Average: 33.325 SF

Annual Rent Value (based on Class A Office @ $30/sf)

$999.75

25-year Cash Flows(based on 2.5% inflation)

$34,149.22

Net Present Value (based on 9% discount rate)

$12,156.48

Assuming a discount rate of 9%, rent value of $30 per foot annually, and a 25 year life, the net present value of that space to the property owner is $12, 156.48.


NPV: Landlord has lost this amount of value by placing CBPA inside.

$12,156.48

CONSIDER:

1.If space is recaptured for rental value, what will my alternative cost be?

2.Will placing the system outside cost more or less than $12,156.48?

3.If it’s less, then how much less? (I don’t like the look of a box outside.)


Aboveground heated enclosure for 3” BPA with heat.

Option A: Use conventional model e.i., Watts 957 NRS

Safe-T-Cover 300-AL-H$3,266.00

72 X 38 X 22 = 60K CI

Option B:

Use new ”n-type” model e.i., Watts 957N NRS

Safe-T-Cover 200SN-AL-H$1,120.00

46 X 38 X 19 = 33K CI


$1,000

$1,120

$1,800

$3,920

$3,266

$1,200

$1,800

$6,266


Indoor CBPA

$3,920.00 plus assembly



Owner’s Cost: 3” Domestic line


“How much more value does my building have with the additional rent?”

ANSWER:

Year Annual Rent*1 $999.75

PropertyValue*$10,289.09

5 $1,103.54 $11,357.2310 $1,248.55 $12,849.6715 $1,412.62 $14,538.2220 $1,598.25 $16,448.6625 $1,808.27 $18,610.15

* - Today’s dollars: Assumptions: Annual rent growth of 2.5%; 5% vacancy; 35% operating expenses; capitalization rate of 6%.

Owner’s Property Value


No more DCs on commercial or industrial properties.

Chicagoland, IL

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Elgin, October 2012

5. The Explosive Growth of the RPZ

Chicagoland, IL

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Naperville, April 2013

Naperville already required RPZs on their commercial irrigation systems, but after Elgin’s action, they too outlawed DCs, and in fact, extended mandatory RPZ use on fire line systems as well.


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Atlanta Area, GA

Roswell, August, 2014

Roswell detailed two methods of RPZ placement, one indoors for small sizes, and one outdoors for larger sizes.


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Atlanta Area, GA


The drawings for the indoor method explicitly address drain system requirements and force designers to reconcile the flood rate risks with specific drainage system capacities


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Atlanta Area, GA


The chart shows that unless the designer is willing to install an 8” drain system all the way to the sewer inlet, he cannot utilize an indoor solution for any pipe size larger than 2 inches.


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Atlanta Area, GA


And the outdoor method mandates an enclosure that is ASSE-1060 compliant.


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Delaware, June 2013

Columbus Area, OH


North central Texas

AlpineBedfordBoerneCarrolltonCleburneCollege StationDenisonFarmingtonFarrisFranklinGrand PrairieHaltomTexarkanaWacoWaskomWhite Settlement

AddisonArlingtonBudaCedar HillColleyvilleCrowleyDentonDuncanvilleFort WorthFranklinGainesvilleHighland VillageMidlothianRoanokeRound RockSaginaw

Same language added to muni code

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AlpineBedfordBoerneCarrolltonCleburneCollege StationDenisonFarmingtonFarrisFranklinGrand PrairieHaltomTexarkanaWacoWaskomWhite Settlement

AddisonArlingtonBudaCedar HillColleyvilleCrowleyDentonDuncanvilleFranklinGainesvilleHighland VillageMidlothianRoanokeRound RockSaginaw

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DFW, TX

Fort Worth, July, 2010

Since then, all these Texas cities have added it to their own code.


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Central VA

Lynchburg, 2008

Lynchburg has required RPZs on all non residential connections for almost a decade. This includes domestic, irrigation, and fire lines.


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Mountain West

Denver, February, 2013

In 2013 Denver Water added new standard details for 3” and larger RPZs to be installed outdoors.


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Mountain West

Denver, February, 2013

They even call for double checks for public park drinking fountains to be installed above ground in a heated enclosure.


Seattle, WA

Raleigh, NC

Charlotte, VAAustin, TX

Nashville, TN

Albuquerque, NM

Long Island, NY

Denver, CO

Las Vegas, NV

Lynchburg, VA

Columbus, OHChicago. IL

Forth Worth, TX Roswell, GA

Longview, WA

Arlington, TX

Gwinnett Cty, GA

Chesapeake, VA

Olympia, WA

Kent, WA

Franklin, TN

All these cities have made changes whereby RPZ use has been expanded either by lowering or eliminating the hazard threshold for use on domestic water lines in the past 5 years. (These are the cities we know of….)

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Charlotte, NC

Denver, COColumbus, OH

Roswell, GAArlington, TXGwinnett Cty, GALas Vegas, NV

6. What are the Best Practice Examples around the Country

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Perfect StormConsider the ‘worst case scenario’ of a water volume discharge of a containment backflow prevention, namely, an uncontrolled discharge caused by a failure of the #1 check valve contemporaneous with the relief valve being stuck or propped open by debris. If there is no faucet demand within the commercial premise, such as over night, then this perfect storm produces an unmitigated flow of all available water through the relief valve continuously. The management of this sudden water deluge is a significant hazard. As severe as the most severe storm water runoff event.

Special Insert

This hazard is clearly work found within the civil engineering discipline rather than the plumbing engineering discipline. Designing and specifying any outdoor containment BPA – even if it is placed within the jurisdictional boundaries of the plumbing engineer, is asking for trouble.

A survey of 1869 civil and mechanical engineers was conducted by Safe-T-Cover and EnviroDesign Management over a 22-month period ending in Spring, 2016. The survey followed a professional learning module delivered by EnviroDesign and was managed and tabulated by Benchmark Email Services. Excluding delivery failures, 1220 were delivered and opened. The following 2 slides show the questions in the short survey and the responses.

7. How do we Encourage transition to Civil Engineers

Develop a firm-level policy

ASPE local chapter dialog with local water purveyor

Encourage best practices learning

Publish standard details and drawings consistent with best practices


Plumbing engineers are facing new liability risks from insurance carriers, revealed by new warnings and commentary from industry leadership regarding indoor containment RPZs.

The need to address sudden flood water flows disqualifies MEP from CBPA Design.

Take-Aways

Your local water district must be encouraged to adopt new details and guidelines that promote best practices and adoption by CEs.

Indoor placement of 3” & > RPZs adds irrational risk for PO & designer.

Placing the CBPA inside costs PO $000s more than outside.

Because of the need for pure water in the public water supply and the undetectable nature of the DCs, purveyors are demanding more RPZs and ignoring the legacy hazard guidance.

In order to plan for hazard-change and rule-change retrofits, even DCs should be positioned in a location suitable for RPZ.

RPZs are designed to engulf the immediate surrounding area.

Please complete the session evaluation in the ASPE 2016 app or online at aspe.org/sessions.

Your feedback is greatly appreciated.

CEU certificates will be emailed to attendees within 2 weeks after the conference.

Thank you

Aspe nat'l convention let civildsncontmtsys slideshare

Engineering

Transcript of Aspe nat'l convention let civildsncontmtsys slideshare