Incidents and Events 2009

1. Incidents and Events 2009 Kathryn Buist 23 June 2010

2. Contents • Background • 2009 performance • Event types and causes • Event review • Seahouses • North Charlton SR • Hulne Park, Alnwick • Summary

3. Notifications • DWI notified on 23 occasions in 2009 • 10 classified as cat 3 – significant • In the Northern region 86 events notified, 49 significant

4. Notifications / Incidents - numbers

5. Incidents 2009 • Jan 1 - Leadgate, discoloured water • March 2 - Metaldehyde, pesticide • May 3 – Ashington, discoloured water • 4 – Kirkleatham, discoloured water and loss of supply • June 5 – Gosforth, discoloured water • July 6 – Seahouses, micro failure and precautionary boil • August 7 – North Charlton, micro sample failure • November 8 – Northern Trunk main, loss of supply, precautionary boil • December 9 – Brunton Park, discoloured water • 10 –Bedlington, discoloured water

6. 2009 Incident by type

7. 2009 Incident by cause/area

8. Event review - Seahouses • Overview on the wall • Bichwood BPT and Elford SR supplied via NTM from Warkworth • Seahouses – seasonal variation in demand – 622m/day , 750m/d in summer

9. Background - • Samples reported on 22 July 2009 • Reg sample from Elford – 15 p.E.coli and 18 p coliforms • Ops sample from Birchwood - 9 p.E.coli and 29 p coliforms • Discussed with LA and HPA and precautionary advice issued – allow investigation and minimise risk to public health • Network analysis involved • 1,335 advice to boil cards issued • Samples from network

10. Background • Site visits at both sites undertaken on 22 July • Birchwood BPT removed from service • Removal of Elford – network would be starved • - area needed to be rezoned to protect supplies • Sampling organised from 3 local supply chains

12. Some discolouration due to rezoning (10 contacts) • To protect public health and combat potential contamination, residuals were raised • Initially through secondary chlorination, but not effective enough • Manual addition at SR which lead to 1 customer complaint • Widespread flushing could not be done – water resource issue • Targeted flushing as required

13. 2 sets of clear micro samples available on 25 July • Boil advice lifted, cards delivered between 19:30 and 21:55 • Rezoning of area had caused increase in leakage and high demand required tankering for 4 days • Total of 119 micro samples taken over 7 days, 9 were unsatisfactory • (2 from SR and 7 from customer properties – low level coli and E.coli)

14. Further investigations • 23 July – flood test and structural inspection at Birchwood • Ingress identified, repaired and return to service on 12 August • 27 July - flood test and structural inspection at Elford • No ingress identified return to service on 30 July • Air valves on network checked by ops team • Review of maintenance strategy for SR – inspection of 100 SR by March 2010

15. North Charlton no 1 SR - August • Supplied from branch off the NTM • 2 tanks, supply 1,353 properties in total • 29 August 2009, reg sample reported as containing • 1 pres coli (confirmed as 1 E.coli) • Sampling campaign set up • Following samples, residual raised at N Charlton • All results satisfactory • Both compartments were removed from supply to allow flood testing and inspection – all satisfactory • Audit of lab - satisfactory

16. DWI assessment • Critical of – 10 discoloured water contacts 2 consumer contacts for T and O – chlorine no mention of Warkworth data in the 20 day report for N.Charlton Concerned – of ‘hydraulic link’ between the reservoirs. 13km of main between N Charlton and Elford. All other SR on the NTM were satisfactory. NWL responded and incident has been closed

17. Hulne Park November 2009 • NTM from Warkworth - Alnwick area • Number of pumping stations, critical link between Bolton PS and the WTW • Bolton PS has secondary chlorination (0.5mg/l)

18. Warkworth and NTM

19. Hulne Park, Alnwick 8-12 Nov 2009 • Low level alarm at Hedgeley SR followed by lo lo • Maintenance on site at Bolton PS – not delivering water. Assumed to be pumps overheating. • Warkworth WTW confirmed NTM running ok. • 10:40 Hedgeley 0.4m, suction pressure at Bolton PS still low, onsite team conclude Hedgeley SR not receiving water. • TMC involved and Warkworth NTM increased – no improvement • Burst suspected on NTM • DTS requested to walk the NTM to locate burst (8 involved) • Tankering requested for North Charlton SR • 13:20 1st disc water contact received (54 in total from Alnwick) • Step testing done to identify burst location • Exact location identified 16:45

20. 08 November • Assumed discolouration in Alnwick was from increase in mains velocity • Burst location 3m deep, 1.5m away from a lake – limited access only with 4x4 vehicles • H and S issues - trench and flooding • Area around the burst subject to flooding, 6.9km of 12” NTM isolated

25. 08 November • Hedgeley, Wandylaw and North Charlton SR depleting and concern over time for repair, depressurisation and loss of supply. • 23:00 silver team called – Distribution, RCC, WQ, CCC, Production and Emergency Planning • DWI notified based on >50 disc water contacts • Some of network would lose supplies before repair complete • Hedgeley and Wandylaw SR nearly dry, N Charlton and Wandylaw ~12 hrs left. Glororum SR isolated to remain on storage • Decision made for BWN based on depressurisation of rural network 4209 properties • Considered need for alternative supplies and mutual aid tankering • 06:50 1st no water contact received • Liaison with HPA, LA and CCW commenced

26. 09 November • Repair was carried out and NA working on plan for recharge – 36 hours predicted • Static tanks made available, bottled water stations designated • Few opportunities to chlorinate upstream of repair, decision to increase Warkworth to 1.5mg/l. Secondary chlorination increase 1mg/l • All SRs to be hand dosed • 4209 properties received BWN • 18:00 all SR dry (except Glororum). • 280 contacts, 110 for no water and messaging system was used • 2 bottled water stations set up • Hedgeley SR making water and pressure building up at PS upstream of Bolton PS

27. 10 November • Sampling plan for when properties were due to come back on line • 2 sets on first day • BWN to be lifted at earliest opportunity, but ‘blanket lift’ impractical • Withdrawal of static tanks and the bottled water stations • PRV checks in network • Chlorine residuals 1.5-2mg/l • Discussions with HPA regarding lifting of BWN

28. 11 November • 1st set clear samples • Tankers stood down and statics recalled • Chlorine back to target dose • HPA and LA updated • 16:30 second set of samples clear – safe to drink to 1448 properties • 12 November • 2nd set of samples clear – safe to drink to 2761 properties

29. Some facts • 115 micro samples between 8-11 Nov • All clear for coli and E.coli • 687 contacts received • 226 hits on message system. • Website updated 18 times • 32 static tanks (2,200l each) were deployed between 9-11 Nov. • 3 bottled water stations – 52 pallets of bottled water (26,960 l)

30. DWI assessment • Critical of not consulting HPA and LA prior to issuing BWN • This has been rebriefed to the WQ team and the event is closed

31. Summary • Discolouration still an issue • Acceptability managed through AoDW programme for System zone 7 (due date 2012) • A project is in the final business plan for AMP 5 (2010 – 2015) for SZ6