containment backflow installation and design

January, 2017

American Backflow Prevention Association Presentation:

Backflow Installation and Design

Presented byRandy Holland

Environmental Quality Consultant

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

New professional liability risk for engineers

Best Practices: Containment Backflow Preventer Placement

The entire water system design community is struggling with new professional liability risk involving the location of containment backflow preventer systems. This is not because of a new design practice, but because of new information about the old practices. In the past 2 years important organizations and noted 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://blog.safe-t-cover.com/blog/containment-vs-isolation-the-backflow-preventer-installation-battle

https://www.awwa.org/

http://fccchr.usc.edu/

https://www.aspe.org/


It seems very clear that we will not get rid of the problem of placement by ignoring the containment advocates. Advanced Metering Infrastructure (AMI) systems are revealing that more backflow is occurring at the meter than was previously believed. Its far more likely that aggressive containment rules will increase rather than decrease.

The risks are finally being revealed.


And with this new risk realization comes a new Interested Party. The insurance company. Because of this very public commentary from experts, they now have new weapons for damage recovery.

Water utilities are seeking more containment backflow protection than ever before.

Consider:

“…. 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.…”

- preamble to EPA’s Cross Connection Control Manual


More containment systems are being specified as RPZ, regardless of hazard threshold, than ever before.

Consider:


Why?• Older low hazard-use buildings with lead in every plumbing

joint cannot be considered low-hazard forever. • As buildings turn over tenants, they are often transitioned from

low to high hazard uses. Management and enforcement of retrofits is an extraordinary burden• Bad/ignorant actors changing plumbing systems without

permits or oversight..


Consider:For containment, AWWA, ASPE, & the legal community recognize “outside aboveground” as best practice.

1. Why outside?

2. Why not a vault?

3. Momentum: What is driving the change to better solutions?

Today We’ll Cover:


1. RPZs are an indoor flood hazard

Why

Out

side?

Why

not

Insid

e?

“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


Why Outside? Indoor Flood Risk.

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

Best Practices: Containment Backflow Preventer PlacementW

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Flow Stop

The most important thing a designer must understand is the worst case scenario. What can happen. What describes the ‘perfect storm?

We all know that with an RPZ, when water demand stops the water between the valves often evacuates into the relief valve. Some (many) think that that event defines the limit of what water can ever flow into a drain.

Not so.


Loss of pressure

#2 valve blocked

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!


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#1 valve Failure

Normal delivery pressure

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


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#1 valve Failure

Blockage relief valve

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.


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http://blog.safe-t-cover.com/blog/dc-vs-rpz-backflow-prevention-devices





Why

Out

side?

Why

not

Insid

e?Best Practices: Containment Backflow Preventer Placement

Why Outside? Indoor Flood Risk.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.


Why

Out

side?

Why

not

Insid


Why Outside? Indoor Flood Risk.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.


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.

Why

Out

side?

Why

not

Insid




This is 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.

Why

Out

side?

Why

not

Insid



He uses the Manufacturer’s data and 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

Plac

emen

t pra

ctice

s


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

Premise Isolation: Best Practices & Standard Details


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



Charlotte: 32.000 SFColumbus: 36.000 SF

Suffolk Cty: 33.333 SFArlington: 32.000 SF

Average: 33.325 SF

Why Outside? Increase revenue and property value.

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.

Arlington, TX: 32 SF

Why

Out

side?

Why

not

Insid


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.

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.

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

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

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.)

Why

Out

side?

Why

not

Insid

e?


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. 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

Average: 33.325 SF


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

Why

Out

side?

Why

not

Insid

e?


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 plus assembly

$3,266

$1,200

$1,800

$6,266 plus assembly

Irrational Costs, Irrational Risks! W

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Indoor CBPA

$12,156.48 plus assembly


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

ANSWER:

Irrational Costs, Irrational Risks! W

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

Owner’s Property Value



1. Why outside?

2. Why not a vault?




Why

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Vau

lt?

Why not a vault? No RPZs in Vaults


41 states have written code that prohibits the installation of RPZs below grade. And as far as I know, where it remains unwritten, it is invariably enforced as an unacceptable practice.

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

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.

Why not a vault? Confined Space Hazards


hy a

n En

clos

ure?

Why

not

a V

ault?


Why not a vault? Liability


hy a

n En

clos

ure?

Why

not

a V

ault?

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 that that water. Runoff of lawn chemicals alone make this a clear and present danger to the water supply. 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


Why not a vault? Liability


hy a

n En

clos

ure?

Why

not

a V

ault?

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 .


Why not a vault? Changing Demands


hy a

n En

clos

ure?

Why

not

a V

ault?

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.

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.


Why not a vault? Changing Demands


hy a

n En

clos

ure?

Why

not

a V

ault?

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.


Why not a vault? Legal Community Support


hy a

n En

clos

ure?

Why

not

a V

ault? Before his recent death, Indianapolis attorney Doug Cregor

was the nation’s leading litigator of Cross-Connection Control cases.

Douglas Cregor, Esq.

“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

He was quoted in Plumbing Standards Magazine initially in 2009. I most recently saw it republished as part of a blog post on the LinkedIn Group, “MEP Engineers & Managers”:

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’.”


1. Why outside?

2. Why not a vault?




Best Practices: Containment Backflow Preventer PlacementM

omen

tum

This past fall at the Bi-Annual ASPE National conference, one of the learning workshops had this title. The Board President of the Central Texas ASPE, Chris Phillips, a plumbing engineer at Jacobs in SAT contacted me and asked me to deliver the message.

Trade Org. LeadershipWhere is the momentum?


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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 City, GA

Chesapeake, VA

Olympia, WA

Kent, WA

Franklin, TN

Where is the momentum? More RPZs, more outdoors.

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….)

Where is the momentum? Smaller solutions.

12’

6’8” 5’2”

5’4”


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Consider the required enclosure for the industry standard Watts 709 DCDA on the left. It is housed by our Model 1000-AL. It’s 12 feet long and stands 6’8” tall. Compare it to the enclosure required for the Wilkins 450DA on the left. It is housed in our Model 1000TLU880M. It’s 5’4” square and stands just 5’2” tall. These two options offer the same plumbing solution and make a much smaller visual footprint.

http://blog.safe-t-cover.com/blog/why-you-should-get-specific-about-backflow-installation


Where is the momentum? Adjustments for aesthetics.

Mom

entu

m

AWWA has long resisted the practice of placing the BPA near the building because it increased the risk that illegal taps might occur between the meter and the BPA. But Arlington noted that all their indoor RPZs were already “living with that risk”. Enabling the enclosure to reside close to the building dramatically increases the opportunity to screen it with landscaping and thereby improve the aesthetics of the grounds.

Arlington’s decision to add details based on:1. Too much backflow detected through AMI2. Isolation from the inspection process. 3. Non-conforming/Illegal changes after C of O4. Subrogation risks5. Local engineers’ survey

3. Civil engineers are ready to take on the task if SDs exist

Take-Aways1. 3” and larger CBPAs should not be installed indoors and MEPs are

seeking to be excluded from the taska. Indoor flood risksb. Designing for sudden flood water flows exceeds expertise

4. Water/building authorities are feeling pressure to add aboveground standard details so that civil engineers can do this work and improve the safety by advocating safer placement


2. CBPAs should not be installed in subterranean vaultsa. Contamination risksb. Probability of subsequent aboveground retrofit

Thank You!

American Backflow Prevention Association Presentation:

Backflow Installation and Design


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