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Incidents and Events 2009

Incidents and Events 2009. Kathryn Buist 23 June 2010. Contents. Background 2009 performance Event types and causes Event review Seahouses North Charlton SR Hulne Park, Alnwick Summary. Notifications. DWI notified on 23 occasions in 2009 10 classified as cat 3 – significant

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Incidents and Events 2009

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  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

  11. 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

  12. 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)

  13. 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

  14. 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

  15. 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

  16. 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)

  17. Warkworth and NTM

  18. 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

  19. 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

  20. 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

  21. 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

  22. 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

  23. 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

  24. 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)

  25. 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

  26. 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

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