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WRGC Pinpointing Underground Gas Leaks

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Presentation on theme: "WRGC Pinpointing Underground Gas Leaks"— Presentation transcript:

1 WRGC Pinpointing Underground Gas Leaks
Ron Six, Instructor Senior Utility Consultant AEGIS Insurance Services, Inc. 201/

2 Associated Electric Gas Insurance Services
A E G I S Associated Electric Gas Insurance Services Before I begin my presentation, some of you may not be familiar with AEGIS, so let me take just a moment to tell you who AEGIS is. AEGIS is an acronym that stands for Associated Electric and Gas Insurance Services. First Response

3 AEGIS Background 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 AEGIS is a mutual insurance company formed nearly 30 years ago. Discuss slide. First Response

4 Our main job is not finding & fixing leaks Our main job is public safety

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

6 Major Causes of Leaks Corrosion Mechanical failure
Improper installation Improper design Faulty materials 3rd Party Damage - “Dig-Ins”

7 ASH ST #682 #686 4” Plastic Main 45 PSI Water Main
Dead Cast Iron Gas Main First Response

8 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.

9 Our main job is not finding & fixing leaks Our main job is public safety

10 Detect Pinpoint Repair

11 Evaluating The Leak Where is the gas? w h e r is the gas?

12 Evaluating The Leak W H E R here is the gas? ow much is there? xtent of hazard (migration) elation to other structures valuate/evacuate

13 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

14 Centering = Where is the gas?
Pinpointing = Where is the leak? The leak must be centered before it is pinpointed

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

16 Recent Natural Gas Incidents
Springfield, MA

17 Methods Of Locating The Line
Maps Records System experience Electronic locators 1. Basic principles of operation 2. Inductive vs. Conductive 3. Overcoming problems

18 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)

Where and how many? What size test holes? How deep? How far apart?

20 Size of the Test Hole ½” Test Hole ” Test Hole

21 From the 1” Test Hole vs. the ½” Test Hole
Size of the Test Hole ½” Test Hole ” Test Hole 4x’s the Aeration From the 1” Test Hole vs. the ½” Test Hole

22 The Size of the test hole is critical
Pinpointing with a ½” test hole Pinpointing using a 1” test hole

23 Minnich Hornet Drill


25 OLD MAIN STREET #400 #402 #404 30% Gas @ Foundation Wall
90% Curb Concrete Sidewalk 4” Bare Steel 45 PSI OLD MAIN STREET #400 #402 #404

26 Use Of Soil Purger (cont’d)
The soil purger is your best friend or worst enemy, depending on where and how it is used First Response

27 Types of Soil Purgers


29 Never purge near foundation
#404 #402 #400 Never purge near foundation 30% Foundation Wall Concrete Sidewalk 90% 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

30 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.

31 60% Gas Curb 8” Steel UP CWP Maple Street 15% Gas

32 Maple Street 60% Gas 15% Gas Curb Service Line 8-10’ 8” Steel UP CWP
70% 50% 75% 8-10’ Maple Street 60% Gas 15% Gas

33 Maple Street 60% Gas 15% Gas Curb Service Line Slope 8” Steel UP CWP
40% 35% 45% 0% 15% 50% 10% Maple Street 60% Gas 15% Gas Curb Slope

34 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

35 Test Methods Combustible gas indicator Natural ventilation
1. Top & bottom of hole 2. Time the readings Natural ventilation 1. Wait…let holes vent Blow pipe – vapors/soap top of hole Odor

36 Never use near foundation of building
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

37 10% Gas In Sewer Manhole 6” Steel UP ASH STREET CURB LINE

38 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 CGI Test CGI Test

39 “Make Your Mark” Using Your Experience Using Test Results
Using System Design Remember: It is much cheaper to drill than to dig. Do you have enough holes to give you enough information about the leak?

40 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?

41 6” Low Pressure Cast Iron
High School 4” High Pressure Steel 25% gas in sewer manhole K-Street 6” Low Pressure Cast Iron 15% curb 65 69 71 67

42 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

43 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”

44 Chromatographic Analysis Comparison
No Ethane CO2 Methane Sewer Gas Nitrogen Ethane Natural Gas

45 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

46 Be Alert Be Prepared Be Safe

47 AEGIS Insurance Services, Inc. Thank You Please visit our website @
Thank you for the opportunity to speak with you today and to participate in your conference. The Loss Control Division is here to contribute to your continued success. Thank you. CLICK First Response

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