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Preparation for Depressurization:How to Survive a Major Water Main Break
Preparation for Depressurization:How to Survive a Major Water Main Break
Preparation for Depressurization:How to Survive a Major Water Main Break
Preparation for Depressurization:How to Survive a Major Water Main Break
Preparation for Depressurization:How to Survive a Major Water Main Break
Preparation for Depressurization:How to Survive a Major Water Main Break
Preparation for Depressurization:How to Survive a Major Water Main Break
Preparation for Depressurization:How to Survive a Major Water Main Break
Preparation for Depressurization:How to Survive a Major Water Main Break
Preparation for Depressurization:How to Survive a Major Water Main Break
Preparation for Depressurization:How to Survive a Major Water Main Break
Preparation for Depressurization:How to Survive a Major Water Main Break
Preparation for Depressurization:How to Survive a Major Water Main Break
Preparation for Depressurization:How to Survive a Major Water Main Break
Preparation for Depressurization:How to Survive a Major Water Main Break
Preparation for Depressurization:How to Survive a Major Water Main Break
Preparation for Depressurization:How to Survive a Major Water Main Break
Preparation for Depressurization:How to Survive a Major Water Main Break
Preparation for Depressurization:How to Survive a Major Water Main Break
Preparation for Depressurization:How to Survive a Major Water Main Break
Preparation for Depressurization:How to Survive a Major Water Main Break
Preparation for Depressurization:How to Survive a Major Water Main Break
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Preparation for Depressurization: How to Survive a Major Water Main Break

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Case Study of planning for a Major Main Break based on an actual event in Delaware, Ohio.

Case Study of planning for a Major Main Break based on an actual event in Delaware, Ohio.

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  • 1. Preparation for Depressurization: How to Survive a Major Water Main Break Dr. Thomas Marshall, PE City of Delaware Dan Barr, PE Burgess & Niple, Inc.
  • 2. Objectives of this Presentation <ul><li>1) Present a case study of a recent major water main failure in the City of Delaware in order to provide insight into proper response and lessons learned </li></ul><ul><li>2) To learn the advantages of a having a calibrated water model during a water main break </li></ul>
  • 3. Case Study City of Delaware 16” Transmission Line Break Dr. Thomas Marshall, PE City of Delaware
  • 4. Case Study City of Delaware 16” Transmission Line Break of December 2005 <ul><li>Introduction </li></ul><ul><li>Background </li></ul><ul><li>Logistics and Response </li></ul><ul><li>Lessons Learned </li></ul>
  • 5. Case Study: Introduction <ul><li>City of Delaware, Ohio is located approximately 30 miles north of Columbus </li></ul><ul><li>Established in 1856, the community has aging infrastructure in addition to a recent surge in growth – one of the highest growth areas in the nation </li></ul><ul><li>Projects currently under contract total over $75M and include a wastewater plant expansion, elevated water tower construction, multiple water, storm and sewer line projects, and water treatment plant expansion planning </li></ul>
  • 6. Case Study: Background <ul><li>12/28/06 11:15 A.M. Contractor snags 16” transmission main which supplies 70% of the City’s water </li></ul><ul><li>The other 16” main supplying the City dates back to the 1800s and will convey less than 30% of the City’s 6 MGD average daily demand </li></ul><ul><li>The level in both of the City’s 1 million gallon elevated storage tanks began dropping rapidly </li></ul><ul><li>Major portions of town were experiencing lower water pressures </li></ul>
  • 7. Case Study: Background <ul><li>OUPS ticket was misread, wrong line was marked </li></ul><ul><li>Line was not shown on project plans </li></ul><ul><li>Multiple pipeline projects were in progress in the area </li></ul><ul><li>Line located in the back of the Delaware County Fairgrounds – 6’ to 8’ of debris and backfill was placed over line since installation </li></ul><ul><li>City, contractor, engineers, and EPA very short staffed due to Christmas Holiday </li></ul>
  • 8. Case Study: Logistics and Response <ul><li>The following steps were taken within approximately 30 minutes of the failure: </li></ul><ul><ul><li>Distribution Superintendent was informed of incident </li></ul></ul><ul><ul><li>Water plant operator, support staff, police, fire and City officials were immediately informed </li></ul></ul><ul><ul><li>Incident command center was established at the site – crews were called in to respond </li></ul></ul><ul><ul><li>OEPA was notified and consulted </li></ul></ul><ul><ul><li>Burgess & Niple was contacted to evaluate the impact of the break using the distribution model </li></ul></ul>
  • 9. Case Study: Logistics and Response <ul><li>Steps that followed: </li></ul><ul><li>Immediate efforts focused on isolating failure </li></ul><ul><li>Emergency connection to adjacent water purveyor was activated </li></ul><ul><li>City officials implemented reverse 911 emergency system for affected customers </li></ul><ul><li>Media outlets advised </li></ul><ul><li>Ongoing Water Model and field data collection </li></ul><ul><li>Ongoing OEPA communication </li></ul><ul><li>Elevated storage tanks still draining at an alarming rate </li></ul>
  • 10. Case Study: Logistics and Response <ul><li>Steps that followed (continued) </li></ul><ul><li>Break was isolated – This was complicated by connections to the line that were not shown on old, inaccurate subdivision plans. </li></ul><ul><li>Elevated storage tower elevations perilously low </li></ul><ul><li>A plan for repairing and disinfecting the line was developed with guidance from OEPA </li></ul><ul><li>Repair was made </li></ul><ul><li>Disinfection plan was implemented </li></ul>
  • 11. Case Study: Logistics and Response <ul><li>Disinfection Approach </li></ul><ul><ul><li>HTH was used to super-chlorinate the 2250 feet of depressurized main for 30 minutes </li></ul></ul><ul><ul><li>Samples were taken and analyzed for chlorine residual at both ends of the isolated segment of main after 30 and 90 minutes </li></ul></ul><ul><ul><li>Chlorine residual values of the 30 and 90 minute samples were compared – values were unchanged </li></ul></ul><ul><ul><ul><li>A reduction in chlorine residual from the 30 to 90 minute samples would indicate more time was needed for disinfection </li></ul></ul></ul><ul><ul><li>Isolated segment of main was flushed for 30 minutes </li></ul></ul><ul><ul><li>Samples were taken again – chlorine residual was at normal value </li></ul></ul><ul><ul><li>Line was placed back in service </li></ul></ul>
  • 12. Case Study: Lessons Learned <ul><li>Delaware needs more elevated storage! (2 MGD under construction) </li></ul><ul><li>Delaware needs addition main lines (24” in design) </li></ul><ul><li>Improve quality assurance on OUPS tickets </li></ul><ul><li>Work toward a GIS-based line and valve mapping system </li></ul>
  • 13. Case Study: Lessons Learned <ul><li>Work closely and early with OEPA during major events </li></ul><ul><li>Reverse 911 automated calling works with about 80% effectiveness </li></ul><ul><li>It is very helpful to have a previously calibrated water distribution model </li></ul>
  • 14. The Advantages of a Calibrated Water Model During (and Before) a Water Main Break Dan Barr, PE Burgess & Niple, Inc.
  • 15. What Are the Advantages? <ul><li>A calibrated water model can: </li></ul><ul><li>Determine the impact of a leak </li></ul><ul><li>Determine the impact of an out of service main </li></ul><ul><li>Help decipher abnormal results from the incident </li></ul><ul><li>Reinforce the system before a break occurs </li></ul>
  • 16. Determining the Impact of a Leak <ul><li>To determine the impact of a leak: </li></ul><ul><li>Enter the leak into the model as a large demand at the main break location </li></ul><ul><li>Use a variety of leak estimates to determine the significance of the impact including fire flow analysis tools </li></ul>
  • 17. Determining the Impact of a Leak (cont.) <ul><li>To determine the impact of a leak: </li></ul><ul><li>Use the model to determine the lowest pressures in the system – local and system-wide. Useful when determining boil alert locations </li></ul><ul><li>If the leak can’t be isolated quickly, use the model to predict how the distribution system will perform under high leak demands over time </li></ul>
  • 18. Determining the Impact of an Out-of-Service Main <ul><li>This can be done by: </li></ul><ul><li>Closing the affected pipe in the model </li></ul><ul><li>Running simulations over time to determine how well the elevated storage tanks fill and drain. </li></ul>After the main is isolated and the leakage stopped, the model can predict the system’s performance when the main is out of service.
  • 19. Deciphering Abnormal Results from the Incident <ul><li>Locate unknown, previously closed valves </li></ul><ul><li>Locate unknown pipe connections </li></ul><ul><li>Identify if valves are incorrectly closed </li></ul><ul><li>Discover multiple leaks </li></ul>When the model results do not align with the field results, use the model to:
  • 20. Optimizing the System Before a Break <ul><li>Complete the activities mentioned previously in advance </li></ul><ul><li>Use results from trial runs and leak simulations to determine the best corrective actions </li></ul><ul><li>Study the distribution system and identify/correct the weak points before a major break occurs </li></ul>
  • 21. Summary <ul><li>Mistakes </li></ul><ul><li>Lost water </li></ul><ul><li>Customer boil alerts </li></ul>Using calibrated water models during a water main break can minimize:
  • 22. Any Questions?

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