Water Main Break Response and Repair Procedure

Purpose. This procedure sets out how network crews respond to, isolate, repair, disinfect and return to service a broken water main while protecting the public, the crew and the water quality of the network.

1.Response

The control centre creates a work order for every reported break and dispatches the on-duty or standby crew with a priority based on the loss of supply, property damage risk and traffic impact. The crew must arrive within the service standard, assess the break, set up traffic control and exclusion barriers, and report back to the control centre within 15 minutes of arrival with the isolation plan and the number of customers affected.

2.Isolation and customer notification

Identify the valves to close from the network plans and confirm the isolation on site. Before closing, the control centre must notify affected customers through the interruption message and directly contact registered critical customers such as dialysis patients, the hospital and food processors. Keep the isolation to the smallest area that stops the flow. Record the valves closed on the work order.

3.Excavation

Before breaking ground, locate and mark all services using the plans, the utility referral service response and an electronic locator, and pothole by hand to expose services near the dig. Excavations deeper than 1.5 metres must be shored or benched and require an excavation permit in the Permit to Work Register. Keep spoil and machinery clear of the edge. Dewater the excavation so the break can be inspected safely.

• Utility plans and referral response on site
• Electronic locate and hand potholing
• Shoring or benching over 1.5 metres
• Spoil and plant set back from the edge
• Ladder access and egress in place

4.Repair

Cut out the damaged section and fit a repair clamp or replace the pipe section with the fittings specified for the pipe material and pressure class. Keep the open pipe ends capped or above any water in the excavation so that contaminated water does not enter the main. Flush any dirt from the pipe before the final joint is made.

5.Disinfection and return to service

Swab the repaired section and fittings with a chlorine solution of at least 1 percent before assembly. Recharge the main slowly with the downstream hydrant open, flush until the water runs clear and the free chlorine residual matches the network residual, and record the residual on the work order. Where the main was depressurised with sewage or floodwater nearby, or the pipe was open for more than four hours, collect a bacteriological sample and notify the water quality team before returning the main to unrestricted service.

6.Reinstatement and records

Backfill in compacted layers, reinstate the surface to the road authority standard and remove traffic control only when the surface is safe. Complete the work order with the cause of the break, the pipe material, the repair method, the residual, the samples taken and the time supply was restored. Report any near miss or injury on the Incident Report Form.