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

201/417-2487

RonaldSix@aegislimited.com

WRGC Pinpointing Underground Gas Leaks

A E G I SA E G I SAAssociated EElectric GGas IInsurance SServices

• 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

AEGISAEGISBackground InformationBackground Information

Our main job is not finding & fixing leaks

Our main job ispublic safety

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

Pinpointing

Major Causes of Leaks

• Corrosion

• Mechanical failure

• Improper installation

• Improper design

• Faulty materials

• 3rd Party Damage - “Dig-Ins”

#682 #686

Dead Cast Iron Gas Main

Water Main

4” Plastic Main 45 PSI4” Plastic Main 45 PSI

ASH STASH ST

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 ispublic safety

Detect

Pinpoint

Repair

w

h

e

r

e

is the

gas?

Evaluating The Leak

Where is the gas?

Evaluating The Leak

here is the gas?• W• H• E• R• E

ow much is there?xtent of hazard (migration)elation to other structuresvaluate/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 leak must be centered before it is pinpointed

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

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

Recent Natural Gas Incidents Springfield, MA

Methods Of Locating The Line

• Maps

• Records

• System experience

• Electronic locators1. Basic principles of operation2. Inductive vs. Conductive3. 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?

19

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 Aeration4x’s the AerationFrom the 1” Test Hole vs. From the 1” Test Hole vs.

the ½” Test Holethe ½” Test Hole

The Size of the test hole is critical

Pinpointing with a ½” test hole Pinpointing using a 1” test hole

22

Minnich Hornet Drill

SAVE

ANOTHER

MISSED

EXCAVATION

30% Gas @ Foundation Wall

90% Gas @ Curb

Concrete Sidewalk

4” Bare Steel 4” Bare Steel 45 PSI45 PSI

OLD MAIN STREETOLD MAIN STREET

#400#402#404

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

30% Gas @ Foundation Wall

90% Gas @ Curb

Concrete Sidewalk

8” CI UP8” CI UP

OLD MAIN STREETOLD MAIN STREET

#400#402#404 Never purge Never purge near foundationnear foundation

Never purge Never purge near foundationnear foundation

Purge Away From Purge Away From FoundationFoundationThis will draw the gas away from This will draw the gas away from the building and block the gas from the building and block the gas from migrating to the foundation wallmigrating to the foundation wall

Purge Away From Purge Away From FoundationFoundationThis will draw the gas away from This will draw the gas away from the building and block the gas from the building and block the gas from migrating to the foundation wallmigrating to the foundation wall

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

• You must not leave 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

15% Gas

8” Steel UP CWP

Maple Street

Curb

8” Steel UP CWP

Curb

Service Line

70%

50%

75%

8-10’ 8-10’

Maple Street

60% Gas

15% Gas

8” Steel UP CWP

Service Line

40%

35%

45%

0%15%

50%50%50%45%10%0%

Maple Street

60% Gas

15% Gas

Curb

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 indicator1. Top & bottom of hole2. Time the readings

• Natural ventilation1. 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 process2. As a safety tool –

Never use near foundation of building3. Residual gas

• Choosing a purge point is the key

• Techniques

10% Gas In Sewer Manhole

6” Steel UP6” Steel UP

ASH STREETASH STREET

CURB LINE

Manhole

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

Using Test ResultsUsing Test Results Using System DesignUsing System Design

Using Your ExperienceUsing Your Experience

“Make Your Mark”

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

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

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 SchoolHigh School

6565 6969 7171

K-StreetK-Street

6” Low Pressure Cast Iron6” Low Pressure Cast Iron

4” High Pressure Steel4” High Pressure Steel

6767

25% gas in sewer manhole25% gas in sewer manhole

15% gas @ curb15% gas @ curb

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”

Ethane

No Ethane

Natural GasNatural GasNatural GasNatural Gas

Sewer GasSewer GasSewer GasSewer Gas

MethaneNitrogen

CO2

Chromatographic AnalysisComparison

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.AEGIS Insurance Services, Inc.Thank You

Please visit our website @www.aegislink.com