Backflow Best Practices and Standard Details: Part 2

Sponsored by
Randy Holland
Premise Isolation Backflow Prevention:
Best Practices & Standard Details Part 2
Presented by

Part 3: Placement Practices
Premise Isolation Backflow Prevention:
Best Practices & Standard Details

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.

Introduction
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.

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.

Introduction
According 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.

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

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
Placement Practices
3 options for backflow preventer placement

 Inside a vault
Placement Practices
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 vault
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.
 Inside a vault
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
 Inside a vault
2. Liability

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

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.
 Inside a vault
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.
 Inside a vault
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.
 Inside a vault
3. Changing Demands

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

Placement Practices
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.

Placement Practices
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

Placement Practices
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

Placement Practices
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.

Placement Practices
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.

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

Placement Practices
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.

Placement Practices
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.

Placement Practices
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.

Placement Practices
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.

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

Placement Practices
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

Placement Practices
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

Placement Practices
“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

Thank You!

Backflow Best Practices and Standard Details: Part 2

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