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Cross Connections. September 29-30, 2011 Drinking Water Program Sustained Compliance Workshop Lee Johnson, P.E. [email protected] 907-451-2179. Objectives. What is a Cross Connection? How are they regulated? What is a Back Flow Preventer? Types of Preventers

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Cross connections

Cross Connections

September 29-30, 2011

Drinking Water Program

Sustained Compliance Workshop

Lee Johnson, P.E.

[email protected]

907-451-2179


Objectives

Objectives

  • What is a Cross Connection?

  • How are they regulated?

  • What is a Back Flow Preventer?

  • Types of Preventers

  • Examples of Cross Connections


What is a cross connection

What is a Cross Connection?

  • Defined in 18 AAC 80.1990(a)(36)

  • Basically it is an ACTUAL or POTENTIAL physical connection or arrangement between otherwise separate piping systems containing potable water and any contaminant, whereby water may flow between the two systems.


Backflow two types

Backflow – TwoTypes

Back Pressure:

Pressure of nonpotable fluid is greater than pressure of potable water.

Back Siphonage:

Negative pressure in potable water piping causes nonpotable fluid to be siphoned into potable water line.


High or low hazard

High or Low Hazard

  • Low Hazard - will not have an immediate effect on health, but could have an impact on the potable water.

  • High Hazard - will cause an immediate toxic effect or cause immediate and severe illness.


Cross connections are prohibited

Cross Connections Are Prohibited

18 AAC 80.025(a)

A person may not construct, install, or use a cross connection in a public water system, or allow a water system that contains a cross-connection to connect to a public water system.


Cross connections

18 AAC 80.025(b)

If the department determines that a facility has the potential to contaminate public water system through backflow, the owner or operator of the public water system shall install, maintain, and test on the service line to and at other locations in that facility, a backflow prevention device that conforms to ANSI/AWWA Standards C510-97, Double Check Valve Backflow prevention Assembly, or C511-97, Reduced-Pressure Principle Backflow Prevention Assembly, adopted by reference in 18 AAC 80.010(b).


18 aac 80 025 b continued

18 AAC 80.025(b) continued

The owner or operator of the public water system may delegate the installation, maintenance, and testing of the backflow prevention device to the owner or operator of the facility that poses the risk. This delegation does not relieve the owner or operator of the public water system of the responsibility to install, maintain, and test the backflow prevention device.


Statutes codes

Statutes & Codes

  • Alaska Statutes:

    • Article 8 Section 18.60.705

  • Portions of Uniform Plumbing Code – 2009 adopted by reference, 18 AAC 80.010(c)

    • UPC Chapter 6

      • Section 603 pertains to Cross Connections

      • Table 6-2 Backflow Prevention Devices, Assemblies, and Methods


Service connections and premise plumbing

Service Connections and Premise Plumbing

  • Drinking water program regulates water systems – Sources , treatment, and distribution systems, not service connections.

  • There is risk within a building from cross connections even if distribution system is protected. Plumbing Code

  • What about cross connections within your facility?

  • Need to protect potable taps from nonpotable use taps within water plant.


Plan review sanitary survey

Plan Review & Sanitary Survey

  • During engineering plan reviews we look for Cross Connections within the public water system, the treatment plant, and the water distribution system.

  • BUT…….. For existing systems the sanitary survey process is the only other opportunity for staff or inspectors to look for and ask questions about facilities connected to the distribution system?

  • Also – Systems and plants are often modified through routine maintenance resulting in new cross connections or elimination of backflow prevention.


Owners operators and surveyors s hould consider

Owners, Operators, and Surveyors Should Consider:

Types of facilities connected to drinking water

distribution system (Actual or Potential Hazards?):

  • Health Clinics

  • Hospitals

  • Schools

  • Water and Wastewater Treatment plants

  • Mortuaries

  • Other


Others

Others?

  • What other potential or actual cross connections can you name?


Direct vs indirect

Direct vs Indirect


Devices and assemblies

Devices and Assemblies

  • Device -- cannot be tested

  • Assembly -- has two isolation valves and has test cocks for proper testing of the backflow prevention assembly


Backflow prevention

Backflow Prevention

  • Air Gap

    2 Pipe Diameters or 1 inch minimum

  • RPZReduced Pressure Zone Assembly

  • DCDouble Check Valve Assembly

  • PVBPressure Vacuum Breaker

  • AVBAtmospheric Vacuum Breaker


Backflow prevention1

Backflow Prevention

  • Prevents Backsiphonage

    LOW & HIGH HAZARD

    • Proper Air Gap

    • Atmospheric Vacuum Breaker

    • Pressure Vacuum Breaker

    • Reduced Pressure Zone BFP

    • Double Check Valve (low hazard only)

  • Prevents Backpressure

    LOW HAZARD

    • Proper Air Gap

    • Double Check Valve

      HIGH HAZARD

    • Proper Air Gap

    • Reduced Pressure Zone BFP


Insert new table 6 2

Insert New table 6-2


Cross connections

Protection

Air Gap

Flow condition

Non flow condition

Atmospheric Vacuum Breaker


Cross connections

EXAMPLE AIR GAPS


Cross connections

POTABLE

SUPPLY

FLOAT

NONPOTABLE

APPLICATION

PUMP

Tank

Air Gap


Cross connections

Hose Bibb Vacuum Breaker


Cross connections

Pressure Vacuum Breaker

TEST PORTS

NORMAL FLOW


Cross connections

Double Check Valve


Cross connections

Reduced Pressure Zone Backflow Prevention Assembly (RPZ)

TEST PORTS

#2 CHECK VALVE

PRESSURE

DIFFERENTIAL

RELIEF VALVE

#1 CHECK VALVE

FLOW DIRECTION

#1 GATE VALVE

#2 GATE VALVE

#2 CHECK VALVE

High hazard condition


Cross connections

RPZ


Cross connections

RPZ


Rpz proper installation

RPZ – Proper Installation?


Cross connections

RPZ


Proper installation

Proper Installation?


Cross connections

Priming of raw water pumps with finished water.

Air relief valves piped directly to a drain.

•Cooling water for an emergency generator submerged in a drain or returned to the potable supply.

Pumping Station Cross-connections

AIR VACUUM RELEASE

GATE VALVE

SILENT CHECK

FLOOR DRAIN


Treatment bypass piping

Treatment Bypass Piping


Emergency bypass

Emergency Bypass


Emergency bypass installed

Emergency Bypass Installed


Filter bypass piping

Filter Bypass Piping

Bypass Piping


Disinfection bypass piping

Disinfection Bypass Piping


Water meter as cross connection

Water Meter as Cross Connection?


Submerged inlet

Submerged Inlet


Surface wash arms

Surface Wash Arms


Surface wash arm pressure filter

Surface Wash Arm – Pressure Filter


Backwash waste lines

Backwash Waste Lines


Softener backwash waste line

Softener Backwash Waste Line


Air gap

Air Gap


Uv and cross connections

UV and Cross Connections?


Treatment plant lab sink

Treatment Plant Lab Sink


Cross connections

Distribution System

• Direct connections to sewers for flushing either the water main or sewer.


Distribution issues

Distribution Issues


Resources

RESOURCES

Alaska Drinking Water Regulations

18AAC 80.025

American Water Works Association

Recommended Practice for Backflow Prevention and Cross Connection Control – M14

EPA’s Cross Connection Control Manual

Uniform Plumbing Code

Chapter 6

Kenneth Kerry

Water Distribution System O&M Manual

USC Foundation for Cross-Connection Control and Hydraulic Research

Lots of internet resources


Questions

Questions?


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