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Cross-Bores: How Big is the Issue?

Cross-Bores: How 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. Trenchless Technology for Installing Distribution Lines. Impact Moles. Horizontal Directional Drilling. Should we gamble?.

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Cross-Bores: How Big is the Issue?

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  1. Cross-Bores:How 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

  2. Trenchless Technology for Installing Distribution Lines Impact Moles Horizontal Directional Drilling

  3. Should we gamble?

  4. It’s about Accuracy!

  5. Possible Scenario? Who’s responsible for marking? Sewer Main Lateral to mains connection New service Line House City street Property line What could happen?

  6. Cross-Bored Laterals Can BeFound in Any Neighborhood

  7. Or Any City!!!!

  8. Avoid mechanical cleaning toolswithout verification!

  9. MINNESOTA

  10. MAINE

  11. Headline:February 15, 2002 Officials Seek Answers In Gas Explosion

  12. Headline:February 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.

  13. 3/13/06 Family Escapes as Gas Explosion Levels Home

  14. 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.

  15. Madill, OK 1/2/2007 OK Natural Gas line was installed in 1992

  16. 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

  17. 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.

  18. 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

  19. 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

  20. 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

  21. 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.

  22. 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 AMajor Incident?

  23. Odds of getting a hole-in-one 5,000 to 1 0.02%

  24. 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

  25. In Another City….. • A Four Block Area Was Inspected; • 24 Cross-Bores Were Discovered.

  26. The Greatest Concern CATASTROPHIC PERSONAL LOSSES Because Some Utility Lines Are EXEMPT FROM LOCATING LAWS

  27. 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.

  28. 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

  29. Minimize your risk by conducting an on-site field investigation prior to boring

  30. Confirm the location of existing utilities

  31. Marking Laterals

  32. 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

  33. “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

  34. 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

  35. Question 2 • Do you believe that there needs to be better enforcement of violators?

  36. Question 3 • In the areas where your company/ division does business, are all owners of underground facilities required to mark their plants?

  37. Question 3 (cont’d) • In the areas where your company/ division does business, are all owners of underground facilities required to mark their utilities?

  38. Question 4 • Approximately how many tickets per year does your company/ division typically request?

  39. 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?

  40. 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?

  41. Question 7 • If you answered Yes to Question 5, what is your estimated total cost for the past 5 years for repairing these hits?

  42. 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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