Workshop developed by RCAP/AWWA and funded by the USEPA System Operations: Main Breaks Instructors please mention that this is the second of two modules focused on distribution system operations. This module focuses on main breaks and cross connections, and describes how these events can compromise water quality in the distribution system. Workshop developed by RCAP/AWWA and funded by the USEPA Developed by American Water Works Association with funds from the U.S. Environmental Protection Agency, Published 2015

Learning Objectives Be able to preserve water quality when responding to a water main break Describe the difference between proactive and reactive responses to leaks Be able to describe what a cross connection is and recognize a cross connection

Learning Objectives Continued Be able to describe the seriousness of cross-connections and importance of cross-connection control Describe requirements for cross-connection control Be able to outline the emergency response in the event of a backflow

Main Break: How Does it Happen? Aging infrastructure “a significant water line bursts on average every two minutes somewhere in the country” “$334.8 billion will be needed for pipe, treatment, storage, source and other infrastructure over the 20 year period 2007-26” Pressure surge Mechanical damage 3rd Party damage Sabotage 4

Main Break: How Does it Happen? “The rupture was caused by an emergency pump shutoff that increased pressure from 180 psi to 300 psi.”

Main Break: Consequences Potentially a safety hazard Flooding of surrounding area Property damage Traffic interruptions Water service interruption

Main Break: Consequences (Continued) Loss of pressure Contaminant intrusion May require boil water order or bottled water Loss of finished water High velocity scouring of pipes may dislodge sediments and increase turbidity

Reactive Response to Leaks Valve off section of line if needed Notify MSDH if pressure goes below 20 psi Excavate Repair leak Make sure ALL valves are re-opened

Proactive Response to Leaks Ensure your lines are marked in construction areas Develop a protocol for response to main breaks to limit adverse water quality effects Develop a program to anticipate main breaks Asset Management Buried pipes are the most costly asset of a water utility Prioritize mains that need replacement and get them included in the Capital Improvement Plan

Proactive Response to Leaks Being proactive can reduce costs and protect water quality

Proactive Response to Leaks EPA Asset Management Program Check Up Program for Small Systems (CUPSS) https://www.epa.gov/dwcapacity/information-check-program-small-systems-cupss-asset-management-tool

Disinfecting New Pipes and Returning New Pipes to Service New water mains and those taken out of service should be disinfected before returning to service For additional guidance and information go to: AWWA Standard C651-05 – Disinfecting Water Mains 12

Disinfecting Pipe AWWA: 4-Step Process Flush the line to remove any particulates More effective than burning with chlorine Velocity > 2.5 fps Flush at least 2x the volume of the pipe Chlorinate Should target a dose of 50 mg/L A 5 mg/L residual should remain after 24 hours A higher chlorine dose can be used in exchange for shorter contact time Do not use dry chlorine (HTH) as granules may not fully dissolve

4-Step Process (Continued) Flush to remove chlorinated water (at least 2 full pipe volumes) Chlorinated water must be dechlorinated prior to discharge in some areas Refill the line and perform coliform sampling If results are negative the line is ready to be returned to service (with MSDH’s approval) If results are positive, repeat from step 2 If positive results continue, pigging or additional flushing may be necessary 14

Activity A D Finished water C B E 5. Key Distribution System Components and Their Effects on Water Quality Activity Chlorine A B C Finished water D E Instructors move to the next slide to answer the question. Developed by American Water Works Association with funds from the U.S. Environmental Protection Agency, Published 2015

5. Key Distribution System Components and Their Effects on Water Quality Activity Describe how the following scenarios will affect water quality What would be your concern? What should you monitor for? What else should you do? A fire breaks out at Point D Chlorine metering pump breaks down at Point B Booster pump breaks down at Point C Main break at Point E A rainy week during the summer Half time at the Super Bowl Modeling of distribution system network with EPANet or other modeling software. The key infrastructure including WTP and storage tanks are identified. Developed by American Water Works Association with funds from the U.S. Environmental Protection Agency, Published 2015

Questions?