Report to city council   severe weather jan 2014
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Report to city council severe weather jan 2014

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Review report of high tide events - Dec/Jan 2014

Review report of high tide events - Dec/Jan 2014

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  • 1. To the Lord Mayor and Members of Dublin City Council Report No. 41/2014 Report of the City Engineer Report on Recent Severe Weather Incidents and Exceptionally High Tides As part of the Emergency Flood Plan, DCC has established a Flood Assessment Group (FLAG) that convenes on foot of weather alerts or if there is an increased possibility of flooding arising from the occurrence of predicted high Astronomical Tides or heavy rainfall. The FLAG comprises engineering staff from the operations and maintenance and flood defence sections. They assess the flood risks and determines the measures required to mitigate those risks. For major events, the DCC Crisis management Team is informed of the risks. DCC was aware of a series of high Astronomical Tides occurring from 1st to the 5th January 2014. In preparation for these events an initial FLAG meeting was convened on the 18th Dec 2013 at which arrangements were made to monitor developments leading up to the critical period. The FLAG team members were in conference call daily from 28th December onwards. The following are the measures that were put in place to deal with coastal flooding in particular for the four tides occurring on, 1st January 2014 (2.53m Malin – 12th Highest), 3rd January (3.014m Malin - Highest Ever Recorded), 5th January (2.52m Malin – 15th Highest) and 6th January (2.75m Malin – 4th Highest):         Continuous monitoring and assessment of weather and tidal conditions by DCC staff Liaison with Met Eireann on weather conditions Activation of communications plan involving press releases to public, information on website, information provision to public representatives and other agencies Arrangements made to curtail flows from Poulaphuca (ESB) and Bohernabreena (DCC Water Division) reservoirs Sandbag flood defences and pumps provided along Clontarf Road between Alfie Byrne Road and the Bull Island bridge Sandbag flood defences provided along Strand Road, Sandymount between Marine Drive and St John’s Road East Sandbag flood defences and pump provided at Fitzwilliam Quay to deal with leakage of flood defence wall Public Car Parks closed along Clontarf Road and Strand Road with flood barriers and sandbags
  • 2.   Closed flood gates on the Tolka and Dodder Rivers, at Merrion Gates and on the Liffey Boardwalk Sandbags made available free to public from locations in Clontarf and Sandymount and Stella Gardens from 3rd January onwards. In addition to the above measures, the Flood Assessment Group convened a number of conference-call meetings on a daily basis during the holiday period to continuously review the ongoing risks. These were then communicated to the City Manager, the City Engineer and the Press Office. This task was greatly assisted by the use of tidal modelling (Triton) and telemetry systems, Garda communications and Traffic cameras. The following general resources were deployed by DCC over the critical period to respond to tidal alerts.  Engineering and administration staff  Outdoor operational staff  Plant and machinery  24 Emergency Call Centre  Press Office  Traffic Control Centre  Customer Call Centre  DCC Fire Brigade Equipment on Standby The major issues which mitigated against major flooding of properties was:  The direction of the wind was from the South to South West. If it was from the East, the extent of flooding would have been much greater as on January 3rd 2014 the tide level was overtopping the quays but was not causing damage and flooding was generally confined to the roads.  The lack of rain provided capacity in the existing sewer system. This allowed the overtopping of walls etc. by wave action to be catered for in the sewer system and prevented flooding of properties.  The investment by the OPW and Dublin City Council in flood defences and technology over the last 10 years was repaid on January 3rd as this tide exceeded that of 2002 which flooded 1,200 houses and resulted in estimated damage of €60 million. These flood measures included floodgates and defences on the Rivers Tolka, Dodder and Liffey Boardwalk, sealing beech access openings and providing raised ramp at Sandymount and a new lock gate on Royal Canal to protect East Wall area. Impact assessment on infrastructure and communities In general, given the fact that the highest tide on record was experienced, the impact on infrastructure and communities was relatively low. The sandbag defences in particular at Alfie Byrne Road prevented almost certain flooding of businesses and
  • 3. residences on 3rd January. The closing of the car parks and the sandbagging along Strand road also prevented certain flooding of residential properties. The main inconvenience to the wider community over the period related to traffic and car parking restrictions that had to be implemented. It is likely that the impact would have been a lot more severe if the wind direction was from the east or if the rainfall rate was greater. The following are the main impacts that were experienced:  When the tide levels reached 2.5m Malin Head O.D. flooding occurred on Victoria and Wolfe Tone Quays. The tidal event on 3rd January resulted in these main traffic arteries being closed (12.00 hours) for an hour leading to severe traffic congestion.  The East Link Toll bridge, Strand Road, Marine Road and the Bull Island Bridge had to be closed during the events  A flood defence wall along the Dodder River at Fitzwilliam Quay had significant leakage although no buildings were flooded. Further investigations required to determine the cause and the extent of the remediation works  Flooding of Car parks at Clontarf and Sandymount  Some over topping of City Quay wall at Creighton Street no property flooding occurred as flood waters flowed into the local drainage network  Road flooding through road gullies at Lombard Street  Partial wall collapse at the rear of a car park opposite the Bus Eireann  Two basement residences, one on Clontarf Road and one at the Martello Tower on Strand Road, in addition to a domestic garage on Lea Road were flooded .  Provisional estimated cost to the City Council of €100,000 In comparison with the tide of February 2002, which was lower than that of 3rd January 2014, resulted in the following flooding:  Over top the wall at Fitzwilliam Quay on the River Dodder and collapse of the river bank thus flooding Dermot O’Hurley Avenue, Stella Gardens, Aikenhead Terrace and ultimately across Irishtown Road, St. Brendans Cottages, the Square and Summerfield.  On the opposite bank flood waters over topped the bank at Shelbourne Park, Watermarque Building (partially built), South Lotts, South Dock Road, Doris Street and Gordon Street to Barrow Street and Newbridge Avenue.  In Sandymount, sea water overtopped defences and flooded parts of Marine Drive and Newbridge Avenue, Merrion Gates closing the DART line for 4 hours, portions of Beach Road, Strand road, Seafort Avenue, Newgrove Avenue, St. John’s Road, Sydney Parade Avenue, Guildford Road.  Eastlink Bridge, Victoria Quay, Wolfe Tone Quay, Benburb Street and Sir John Rogersons Quay were flooded and closed to access for a period.
  • 4.  On the north side of the City sea water came up the Royal canal and flooded parts of Shamrock Cottages, Osssary Road, Blyth Avenue, Abbercorn Terrace, Irvine Terrace.  Portions of East Wall road were flooded from the Tolka Estuary.  The Boardwalk was flooded and in many areas along the Quays the tide was 300mm above road level only held back by the Quay walls.  In all over one thousand two hundred and fifty buildings were reported flooded, most of which were residential dwellings. The estimated damage was €60,000,000 (€60m). The Major Management Team which includes the City Manager, City Engineer, Major Emergency Manager, Gardai, Fire Brigade, Press office, Drainage Division, Emergency Services Division monitored and controlled the response on this major risk to the City. During the tidal alert period the City Council acted as the lead agency in liaising with and coordinating the responses of the following agencies:         An Garda Siochana – Traffic The ESB – Control of discharges from Poulaphuca Dublin City Fire Brigade – On standby to attend to floods Civil Defence – mobilised to assist residents in danger of flooding Dublin Bus – Alterations to bus services The Coast Guard Dublin Port Eastlink Company Conclusion In light of the experience gained over the New Year, consideration will be given to strengthening flood defences at a number of locations and especially along the Clontarf Road between Alfie Byrne Road and the Bull Island bridge. While the temporary flood defence measures proved effective on this occasion, it would be foolish to believe that this is a sustainable solution. At some stage either our predictions regarding the tidal height will be proved wrong or the temporary measures will be overcome by a combination of high tide, low pressure, wind speed/direction and rainfall with the result that there will be very extensive flooding in Clontarf area. A more sustainable solution is urgently required if the flooding risk at this location is to be mitigated. Michael Phillips, City Engineer Date : 9th January 2014