Backflow Best Practices and Standard Details: Part 3

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Randy Holland

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

Presented by

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

Part 3: The Explosive Growth of RPZs

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.


http://blog.safe-t-cover.com/blog/containment-vs-isolation-the-backflow-preventer-installation-battle

IntroductionThe 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.


http://www.awwa.org/

http://fccchr.usc.edu/

https://www.aspe.org/

IntroductionCan 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.


IntroductionAnd 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.


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

IntroductionAccording 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.


http://blog.safe-t-cover.com/blog/backflow-preventer-installation-survey-results-from-1200-engineers



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

IntroductionBottom 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


The Explosive Growth of the RPZWater purveyors are increasingly requiring RPZ backflow preventers on all new lines.

Additionally, either of two future events will require a DC assembly to be upgraded to an RPZ - an outcome that is becoming quite common, and will cost the owner thousands of dollars in retrofit expense plus the continued lost opportunity cost from an over sized mechanical room. This happens either when the tenancy changes from low hazard to high hazard through the normal leasing and re-leasing process; or the purveyor changes its definition of what constitutes "high hazard" and now your low hazard user will be re-classified as a high hazard user.

Here are some examples of the cities leading the way with this trend.


No more DCs on commercial or industrial properties.

Chicagoland, ILTh

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The Explosive Growth of the RPZ

Elgin, October 2012


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The Explosive Growth of the RPZ

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, GARoswell, August, 2014

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


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


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Atlanta Area, GAGwinnett County, December, 2016

Gwinnett County is the latest to add standard details for aboveground installation. Note they have chosen to lay out the meter vault as well in order to contextualize the entire layout.


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Delaware, June 2013

The Explosive Growth of the RPZColumbus Area, OH


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DFW, TXFort Worth, 2010

In 2010, Fort Worth added this language to their code, often referred to as the “undetermined tenant clause”.


AlpineBedfordBoerneCarrolltonCleburneCollege StationDenisonFarmingtonFarrisFranklinGrand PrairieHaltomTexarkanaWacoWaskomWhite Settlement

AddisonArlingtonBudaCedar HillColleyvilleCrowleyDentonDuncanvilleFranklinGainesvilleHighland VillageMidlothianRoanokeRound RockSaginaw

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DFW, TXFort Worth, July, 2010

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


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Central VALynchburg, 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 WestDenver, February, 2013

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


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Mountain WestDenver, February, 2013

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


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Another reason: new form factor

12’

6’8”5’2”

5’4”

Another key reason for growth of outdoor installations is the new form factor of the n-type assemblies which reduce the visual envelope of the enclosure by as much as 70% without increasing the net cost.


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Designer Survey Results


A survey of 1869 civil and mechanical engineers focused on standard details 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. 1220 were delivered and opened. The following 2 slides show the questions in the short survey and the responses.

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Designer Survey Results

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


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

http://offers.safe-t-cover.com/a-project-engineers-handbook-5-custom-enclosure-design-considerations?__hstc=57789173.013bbfac08ca4c20d1aed2be0da7d93a.1468961942820.1482327809599.1482328445135.16&__hssc=57789173.1.1482421413842&__hsfp=1471637596&hsCtaTracking=da4c57c1-164b-481c-8119-27db2d1a4a73%7C5f220379-07d5-427f-9454-5670d433f6ad

http://www.arlington-tx.gov/water/arlington-rolls-out-new-engineering-details/

http://www.arlington-tx.gov/water/arlington-rolls-out-new-engineering-details/

Thank You!Premise Isolation: Best Practices & Standard Details


Backflow Best Practices and Standard Details: Part 3

Engineering

Transcript of Backflow Best Practices and Standard Details: Part 3