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
