Containment Backflow Installation and Design

January, 2017
American Backflow Prevention
Association Presentation:
Backflow Installation and Design
Presented by
Randy Holland
Environmental Quality Consultant

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.

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
“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.

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!

#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

#1 valve
Failure
Blockage
relief
valve
Demand
Normal
delivery
pressure
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.

No
demand
Normal
delivery
pressure
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.

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.

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.

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.

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.

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.
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
Watch this video
showing a check
valve failure and
the resulting flood
water flow.
Premise Isolation: Best Practices & Standard Details

Charlotte: 32.000 SF
Columbus: 36.000 SF
Suffolk Cty: 33.333 SF
Arlington: 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
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.

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.)
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
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!
Indoor
CBPA
$12,156.48
plus assembly

“How much more value does my building have with the additional rent?”
ANSWER:
Irrational Costs, Irrational Risks!
Year Annual Rent*
1 $999.75
Property Value*
$10,289.09
5 $1,103.54 $11,357.23
10 $1,248.55 $12,849.67
15 $1,412.62 $14,538.22
20 $1,598.25 $16,448.66
25 $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

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.

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

Why not a vault? Liability
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
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
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
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
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’.”

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.
TradeOrg.LeadershipWhereisthemomentum?

Seattle, WA
Raleigh, NC
Charlotte, VA
Austin, TX
Nashville, TN
Albuquerque, NM
Long Island, NY
Denver, CO
Las Vegas, NV
Lynchburg, VA
Columbus, OH
Chicago. IL
Forth Worth, TX Roswell, GA
Longview, WA
Arlington, TX
Gwinnett City, GA
Chesapeake, VA
Olympia, WA
Kent, WA
Franklin, TN
Whereisthemomentum? MoreRPZs,moreoutdoors.
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”
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.

Where is the momentum? Adjustments for aesthetics.
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’sdecisiontoadddetailsbasedon:
1. Too much backflow detected through AMI
2. Isolation from the inspection process.
3. Non-conforming/Illegal changes after C of O
4. Subrogation risks
5. Local engineers’ survey

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