Cross-Bores: How Big is the Issue?

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Cross-BoresHow Big is the Issue?

• Samuel T. Ariaratnam, Ph.D., P.E.
• Arizona State University
• Dan Weaklend
• NPL Construction Co.
• Las Vegas, NV ? December 9 , 2008

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Trenchless Technology for Installing Distribution
Lines
Impact Moles
Horizontal Directional Drilling
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Should we gamble?
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Its about Accuracy!
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Possible Scenario?
What could happen?
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Cross-Bored Laterals Can BeFound in Any
Neighborhood
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Or Any City!!!!
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Avoid mechanical cleaning toolswithout
verification!
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MINNESOTA
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MAINE
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Headline February 15, 2002 Officials Seek
Answers In Gas Explosion
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HeadlineFebruary 16, 2002Shocked Gas Company
Pleads Ignorance

• The natural gas explosion that rocked a mobile
  home park on Wednesday shocked officials who say
  they never knew their gas line bisected the clay
  sewer pipe.
• A plumbing contractor was removing tree roots
  from a sanitary sewer line in the 127 unit mobile
  home park when the gas line was struck.
• About the only time we know about sewer lines is
  when people call because they get backed up and
  have to call someone in to clean them, said the
  Operations Manager with the local gas company.

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3/13/06 Family Escapes as Gas Explosion Levels
Home
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Middletown, OH 3/16/2006

• After seeing bubbles in the water and smelling
  the natural gas, the plumber told a grandmother
  and her three grandchildren to get out of the
  home immediately.

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Madill, OK 1/2/2007
OK Natural Gas line was installed in 1992
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Mobile, AL

• Action HDD contractor for a gas utility hit a
  sewer lateral on the pilot bore and then hit a
  gas service line on the pullback
• Scenario Gas escaped into the sewer line and the
  house blew up several hours later
• Consequences One critically injured, one
  seriously injured, home was destroyed

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Cincinnati, OH (2006)

• Action HDD contractor installed a gas line
• Scenario Plumber was roto-rooting a sewer
  lateral and pierced a cross-bored natural gas
  line
• Consequences An explosions damaged the house.

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St. Paul, MN (2000)

• Action Cross-bored sewer lateral
• Scenario Plumber was cleaning a sewage blockage
  and struck a natural gas line. He ran upstairs to
  get out but the door was locked.
• Consequences The house blew up and he was
  severely burned

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Rochester, MN

• Action Cross-bored sewer lateral
• Scenario Plumber was cleaning a blocked sewer
  lateral and cut a natural gas line
• Consequences Fortunately, the area was evacuated
  prior to the explosion. Three mobile homes were
  destroyed

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Winona, MN (2001)

• Action HDD crew hit a sewer lateral, while
  installing a gas line
• Scenario Fortunately, the crew had a microphone
  in the sewer main and detected the strike
• Consequences The line was subsequently repaired
  and no incident was recorded

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Bellwood, IL (1997)

• Action Contractor was drilling using HDD
• Scenario The crew hit a sewer lateral and gas
  line.
• Consequences The house blew up however, no
  injuries were reported.

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What are the Odds?
11,000 Laterals Were Inspected in a City
250 Cross-Bores Identified And Repaired
2 of Sewer Laterals Were Hit

• How Many Might Have Led To A Major Incident?

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Odds of getting a hole-in-one
5,000 to 1 0.02
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Other Odds
Becoming an astronaut 13,200,000 to 1
Becoming a pro athlete 22,000 to 1
Writing a NY Times best seller 220 to 1 or 0.45
Royal Flush on first five cards dealt 649,740 to 1
Struck by lightning 500,000 to 1
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In Another City..

• A Four Block Area Was Inspected
• 24 Cross-Bores Were Discovered.

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The Greatest Concern

• CATASTROPHIC PERSONAL LOSSES
• Because Some
• Utility Lines
• Are
• EXEMPT
• FROM
• LOCATING LAWS

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Interesting Interpretations?

• In Kansas and Vermont
• Sewer is not designated as a facility
• In California
• exempts non-pressurized lines
• In Missouri
• exempts privately owned sewer and water lines.

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States Exempt from LocatingSewer Laterals

• CA non-pressurized sewer lines excluded
• KS - Sewer not included in list of items
  designated as facilities
• MO Except sewer lines owned solely by the
  owner or owners of the real property to which
  such lines provide service shall not be
  considered underground facilities
• NJ includes only forced-sewage lines, does not
  include gravity sewers
• NM - Sewer not included in list of public
  utilities
• RI Sewer not included in list of public
  utilities.
• TX Water, Slurry, and Sewage lines excluded
• VT Only gas, electricity, and
  telecommunications are included

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Minimize your risk by conducting an on-site field
investigation prior to boring
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Confirm the location of existing utilities
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Marking Laterals
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Reducing Risks

• Care must be taken when boring near sewer service
  laterals
• Need for assigning responsibility for locating
  and marking these laterals
• Boring contractors need to follow good practices
  during installation of all utilities
• If a blockage occurs, must investigate possible
  causes prior to using mechanical means to
  unblock the lateral

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The Use of Trenchless Excavation Equipment in
Relation to the Marking of Underground Facilities

• DCA HDD Committee
• Arizona State University

Survey Questionnaire Distributed in 2008
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Question 1

• How important is the issue of unmarked sewer
  lines to your business? (10 high 1 low)
• 40 responses were received from trenchless
  contractors in the United States
• Average importance 9.26

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Question 2

• Do you believe that there needs to be better
  enforcement of violators?

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Question 3

• In the areas where your company/ division does
  business, are all owners of underground
  facilities required to mark their plants?

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Question 3 (contd)

• In the areas where your company/ division does
  business, are all owners of underground
  facilities required to mark their utilities?

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Question 4

• Approximately how many tickets per year does your
  company/ division typically request?

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Question 5

• Has your company/division ever had to pay any
  claims as a result of damaging a line that was
  not required to be marked by law or regulation?

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Question 6

• If you answered Yes to Question 5, approximately
  how many times per year during the past 5 years
  have you had to do so?

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Question 7

• If you answered Yes to Question 5, what is your
  estimated total cost for the past 5 years for
  repairing these hits?

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Question 8

• Was there any single claim(s) in excess of
  100,000 (or that resulted in a fatality) that
  was a result of a facility owner not being
  required to mark their lines?

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Question 9

• List any cases of injury or large property damage
  caused by a crossbore that you might have heard
  of that occurred here in the U.S.

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Question 9 (contd)

• List any cases of injury or large property damage
  caused by a crossbore that you might have heard
  of that occurred here in the U.S.

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Question 10

• If you answered Yes to Question 5, what types of
  lines were crossbores?

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Question 11

• What region(s) of the country does your
  company/division typically perform work in?

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Question 11 (contd)

• What region(s) of the country does your
  company/division typically perform work in?

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Conclusions

• Unmarked utilities is a major issue with
  potentially severe consequences
• Better enforcement is required to ensure that
  those responsible for marking utilities do so in
  the interest of public safety
• Trenchless contractors need to use good practices
  in verifying the location of buried utilities
  prior to installation

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QUESTIONS?????