Tullibardine (Auchterarder) - Mains Repair Incident - August 2009

On the afternoon of Thursday 30 July 2009, Scottish Water (SW) started work on shutting down the water supply in the Ochil Road area of Auchterarder so that they could repair a leak on the water main in Ochil Road. An Impact Assessment Form was completed which included the provision to supply most of the customers from a different direction to minimise the number of customer interruptions to just three properties. Work on operating valves and shutting down the supply appears to have been done in accordance with SW's procedures. The main was repaired early on Friday 31 July. Initial indications from the report submitted by SW were that they had not followed their own procedures when repairing the water main. There was a suggestion that the main had not been running full bore when the repair was undertaken and that there was therefore a risk of contamination entering the pipe. Coupled with this was the analysis of the sample of water taken soon after the completion of the repair from a property down stream of the repair in Ochil Road which showed bacteriological contamination. However, when DWQR questioned SW on this, they clarified that the pipe was running full bore and that positive pressure was maintained throughout the repair work. As such, and in accordance with their own procedures, there was no need to take a sample following the repair. DWQR was informed that the sample was taken as a back-up. Nevertheless, the member of SW staff who took the sample failed to follow to correct procedures for this task and in doing so failed to disinfect the tap before flushing it and also neglected to take a measurement of the chlorine residual in the water.

The actions being taken by SW to prevent a recurrence include undertaking a formal meeting with the member of staff who took the sample to address the non-compliance with the sample procedure and the issue of a reminder to all operations staff in the Tay region to ensure that a chlorine residual is taken and recorded for all bacteriological samples and to follow the relevant procedures when working on the distribution system. DWQR has stressed the importance of reminding all staff of the importance of following procedures, not just those in the Tay Region.