Wrgc pinpointing underground gas leaks
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WRGC Pinpointing Underground Gas Leaks. Ron Six, Instructor Senior Utility Consultant AEGIS Insurance Services, Inc. 201/417-2487 [email protected] A E G I S. A ssociated E lectric G as I nsurance S ervices. AEGIS Background Information.

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WRGC Pinpointing Underground Gas Leaks

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WRGCPinpointing Underground Gas Leaks

Ron Six, Instructor Senior Utility Consultant AEGIS Insurance Services, Inc.

201/417-2487

[email protected]


A E G I S

AssociatedElectricGasInsuranceServices


AEGISBackground Information

  • Utility Mutual Insurance Company

  • (member owned)

  • Formed in 1975 by 22 gas utilities

  • Electric Utilities began joining in 1977

  • 375 members – 95% utilities and related energy


Our main job is not

finding & fixing leaks

Our main job is

public safety


Pinpointing

Is not an exact science.It is a developed skill which is learned and perfected through your mistakes and your successes.


Major Causes of Leaks

  • Corrosion

  • Mechanical failure

  • Improper installation

  • Improper design

  • Faulty materials

  • 3rd Party Damage - “Dig-Ins”


#682

#686

4” Plastic Main 45 PSI

ASH ST

Water Main

Dead Cast Iron Gas Main


The“Find and Fix Syndrome”

The cure for this is to ask yourself a question “Where is the gas”? If you can answer the question that the gas is not affecting people and it is not affecting property you are cured. You must ask yourself this question on every leak before you get into the “repair” mode.


Our main job is not

finding & fixing leaks

Our main job is

public safety


Detect

Pinpoint

Repair


gas?

r

w

e

h

the

e

is

Evaluating The Leak

Where is the gas?


Evaluating The Leak

  • W

  • H

  • E

  • R

  • E

here is the gas?

ow much is there?

xtent of hazard (migration)

elation to other structures

valuate/evacuate


Factors Affecting Gas Migration

  • Soil type

  • Soil moisture

  • Surface cover

  • Line pressure

  • Depth of burial

  • Leak size and age

  • Change in elevation=slope

  • Path of least resistance


  • Centering = Where is the gas?

  • Pinpointing = Where is the leak?

  • The leakmustbe centeredbefore it is pinpointed


Centering The Leak

  • Probe holes must be of sufficient depth

  • Test all available openings

  • “Zero out” N-S-E-W

  • You must have sufficient information to make a good judgement

Be Careful – “Don’t make a leak, looking for a leak.”


Springfield, MA

Recent Natural Gas Incidents


Methods Of Locating The Line

  • Maps

  • Records

  • System experience

  • Electronic locators

    1. Basic principles of operation

    2. Inductive vs. Conductive

    3. Overcoming problems


Consistency = Success

  • Exact location of main, services etc.

  • Size of test hole (aeration is the key)

  • Depth of test hole (must be consistent)

  • Location of test holes (same side of main)

  • Instrument use (consistency in testing)


PLACEMENT OF DRILL HOLES

  • Where and how many?

  • What size test holes?

  • How deep?

  • How far apart?


Size of the Test Hole

½” Test Hole 1” Test Hole


Size of the Test Hole

½” Test Hole 1” Test Hole

4x’s the Aeration

From the 1” Test Hole vs. the ½” Test Hole


The Size of the test hole is critical

Pinpointing with a ½” test hole

Pinpointing using a 1” test hole


Minnich Hornet Drill


SAVEANOTHERMISSEDEXCAVATION


#404

#402

#400

30% Gas @ Foundation Wall

Concrete Sidewalk

90% Gas @ Curb

4” Bare Steel 45 PSI

OLD MAIN STREET


Use Of Soil Purger (cont’d)

  • The soil purger is your best friend or worst enemy, depending on where and how it is used


Types of Soil Purgers


#404

#402

#400

Never purge near foundation

30% Gas @ Foundation Wall

Concrete Sidewalk

90% Gas @ Curb

Purge Away From Foundation

This will draw the gas away from the building and block the gas from migrating to the foundation wall

8” CI UP

OLD MAIN STREET


Grade 1 Leak Repairs (Did you find “a” leak or did you find “the” leak?)

  • You mustnotleave a Grade 1 Leak indication as long as the conditions that got you there are still present. If the readings went from 30% gas to 3% gas at the foundation it is still a technical Grade 1 leak. Purge the soil, get the readings to 0%, wait and make sure that the readings do not return.


60% Gas

Curb

8” Steel UP CWP

Maple Street

15% Gas


60% Gas

8-10’

8-10’

Curb

8” Steel UP CWP

50%

70%

75%

Maple Street

Service Line

15% Gas


60% Gas

Curb

35%

15%

0%

8” Steel UP CWP

0%

10%

40%

45%

50%

50%

50%

45%

Maple Street

Service Line

15% Gas

Slope


Using The Soil Purger In The Pinpointing Process

  • Purge from a hole where you know that the leak is not

  • Plug holes near purge point

  • Dense soil or moisture – time the purge/purge each hole

  • Use it only when all other methods have failed


Test Methods

  • Combustible gas indicator

    1. Top & bottom of hole

    2. Time the readings

  • Natural ventilation

    1. Wait…let holes vent

  • Blow pipe – vapors/soap top of hole

  • Odor


Use Of Soil Purger

  • Should not be used on every leak

  • Operation:

    1. In the pinpoint process

    2. As a safety tool –

    Never use near foundation of building

    3. Residual gas

  • Choosing a purge point is the key

  • Techniques


CURB LINE

10% Gas In Sewer Manhole

ASH STREET

6” Steel UP


CGI Test

CGI Test

Gas Readings In Manhole

  • Is gas in the sewer or just using the manhole as a venting point?

  • Test top and bottom

  • Percent gas readings will generally not be sewer gas

Manhole


“Make Your Mark”

Remember:It is much cheaper to drill than to dig.

Do you have enough holes to give you enough information about the leak?

Using Your Experience

Using Test Results

Using System Design


The Dry Hole

  • Probe along the pipe

  • Expose all of the pipe, not just the top

  • Learn from your mistakes

  • Use the hole to your advantage…no one “hits” them all

  • Is it our gas?


High School

4” High Pressure Steel

25% gas in sewer manhole

K-Street

6” Low Pressure Cast Iron

15% gas @ curb

65

69

71

67


Checking After The Repair

  • Did we find “the” leak?

  • Residual gas – when will it go away?

  • Cleanup/plugging the test holes

  • Importance of proper documentation


Stray Gas

  • Is it lighter or heavier than air?

  • Is there ethane in the sample?

  • Is it a hazard?

  • What is sewer gas/decomposition gas?

  • Natural gas vs. stray gas

  • Use of charcoal filter

  • Use of collection bottles/bags

  • Responsibilities regarding stray gas

  • “Reasonable person concept”


Methane

Nitrogen

CO2

Chromatographic AnalysisComparison

No Ethane

Sewer Gas

Ethane

Natural Gas


Remember:The Job Is Not Completed

  • Until all paperwork/documentation is completed:

    • Neatly

    • Thoroughly

    • Accurately

  • You may do everything right, but you may be judged by what is or is not documented


Be Alert

Be Prepared

Be Safe


AEGIS Insurance Services, Inc.Thank YouPlease visit our website @www.aegislink.com


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