waterworks best practices: containment backflow preventer design & placement

…poorly understood by designers

Best Practices: Containment Backflow Preventer Placement

Best Practices:

Containment Backflow Preventer

Design & Placement


“…. 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. …”

Bottom Line for the future:


More Containment More RPZs More Outdoor

Aboveground Installations

Why place a BFP outside?


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?

Why outside?Inside a building can be a major liability.


Where to place a BFP?



Backflow Failure

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

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

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

Why outside?


Charlotte,

NC: 32 SFColumbus,

OH: 36 SF

Suffolk Cty,

NY: 33.3 SFArlington,

TX: 32 SF

How much space is lost?

Average: 33.325 SF

Annual Rent Value: $999.75(based on Class A Office @ $30 psf)

25-year Cash Flows: $34,149.22(based on 2.5% inflation)

Net Present Value: $12,156.48(based on 9% discount rate)


Net Present Value - $12,156.48 “If you pay me this today, I am indifferent to the loss of those income streams over the next 25 years”

QUESTION:Will placing the system inside save $12,156.48 over any other method?

… it depends on how much it costs to put it outside.

What’s that space worth?


Aboveground heated enclosure for 3” BPA with heat.

$1,000

$1,120

$1,800

$3,920

$3,266

$1,200

$1,800

$6,266


Option A: Use conventional model Watts 957 NRS

Option B:

Use new ”n-type” model

Watts 957N NRS

Indoor

Containment

BPA +$12,156.48 +$8,236.48 +$5,890.48

No

Containment

BPA +$0.00

Owner’s Cash Benefit:


3. Fire safety: Indoor water resources for fires unnecessarily add risk to firefighters

Why outside?


1. RPZs are not allowed to be installed in Vaults

Why not a vault?


2. Confined Space Hazards: Vaults are dangerous and expensive to maintain and repair.

New OSHA Guidelines, May 4, 2015: Google: Pre/Post-Entry Information Exchange Duties of Host Employers and Controlling Contractors

Why not a vault?



Why not a vault?

3. Flooded vaults violate the International Plumbing Code.

608.1 General. A potable water supply system shall be designed, installed, and maintained in such a manner so as to prevent contamination from nonpotable liquids, solids or gases being introduced into the potable water system through cross connections or any piping connections to the system.

- International Plumbing Code 2013

4. Aboveground fire BPA enclosures with FDCs are safest, most efficient solution for firefighters

Why not a vault?


5. Retrofits: Water use hazard changes over time –whether by changing tenant or changing guidelines – force enclosure retrofits and leave vaults empty

Why not a vault?


- Plumbing Standards Magazine, Fall 2009

“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.


Why an Enclosure?

6. Insurance Policy

90.%


Texas Survey Results

What do design engineers think?

72.7%



78.2%



Seattle

RaleighCharlotte

Austin

Nashville

Albuquerque

Long Island

DenverLas Vegas

LynchburgColumbusChicago

Forth WorthRoswell


Portland

ArlingtonGwinnett City

Chesapeake

What’s happening around the country that helps us understand where all this is going?

Chicago, IL


Central Ohio


Fort Worth, TX


Fort Worth, TX

AlpineBedfordBoerneCarrolltonCleburneCollege StationDenisonFarmingtonFarrisFranklinGrand PrairieHaltomTexarkanaWacoWaskomWhite Settlement

AddisonArlingtonBudaCedar HillColleyvilleCrowleyDentonDuncanvilleFort WorthFranklinGainesvilleHighland VillageMidlothianRoanokeRound RockSaginaw

Same language added to muni code in past 5 years


Central Virginia


Roswell

did


What Can Cities/Counties Do?1. Adopt standard details consistent with best practices

Denver did



Columbus

did



Charlotte did



Las Vegas did too



Tell DFW to Follow their Lead

The city of Arlington did in February 2016

2710 Landers Avenue ∙ Nashville, TN 37211 ∙ (800) 245-6333

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

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

https://www.facebook.com/SafeTCover

https://www.facebook.com/SafeTCover

https://www.linkedin.com/company/safe-t-cover

https://www.linkedin.com/company/safe-t-cover

https://twitter.com/safetcover

https://twitter.com/safetcover

https://www.youtube.com/channel/UC2w1aN9Ne3kzdB-oPFT6kRg

https://www.youtube.com/channel/UC2w1aN9Ne3kzdB-oPFT6kRg

http://offers.safe-t-cover.com/a-project-engineers-handbook-5-custom-enclosure-design-considerations

http://offers.safe-t-cover.com/a-project-engineers-handbook-5-custom-enclosure-design-considerations