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You are here: BAILII >> Databases >> High Court of Ireland Decisions >> Superquinn Ltd. v. Bray U.D.C. [1998] IEHC 28; [1998] 3 IR 542 (18th February, 1998) URL: http://www.bailii.org/ie/cases/IEHC/1998/28.html Cite as: [1998] IEHC 28, [1998] 3 IR 542 |
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1. In
these proceedings, which were initiated by Plenary Summons which was issued
19th August, 1988, the Plaintiff claims damages for loss it incurred in
consequence of the flooding of its supermarket premises at Castle Street, Bray,
Co. Wicklow on the night of 25th August, 1986 and in the early hours of the
morning of 26th August, 1986 during the course of the storm which has come to
be colloquially known as "Hurricane Charlie". That night the River Dargle
overflowed its banks and caused extensive flooding in the town of Bray and, in
particular, in the area known as Little Bray in which the Plaintiff's premises
are located.
2. When
the hearing commenced in this Court, the proceedings had been discontinued
against two of the Defendants, the County Council of the County of Wicklow and
Powerscourt Estates. In broad outline, the bases of the Plaintiff's claims
against the remaining Defendants are as follows:
3. At
the commencement of the hearing it was agreed by the parties that the
quantification of the damages, if any, to which the Plaintiff is entitled
should be deferred. This judgment is concerned only with the issue of the
liability of the Defendants to the Plaintiff for the damage caused by the
flooding of the Plaintiff's premises.
5. Paddock
Pond was located approximately 14.4 kilometres, measured along the channel of
the River Dargle, upstream of Bray Bridge. The reservoir was formed about a
century and a half ago by the construction of a dam across the northern end of
a natural valley, which was fed by a stream. It was originally part of the
Powerscourt Estate. Historical sources suggest that initially its purpose was
ornamental. In later years it may have been used to power a sawmill
downstream. However, such use had long ceased before the mid-1980's. By then
it was in the middle of an afforested area and its only practical benefit to
its owner would appear to have been that the roadway which was constructed on
the top of the dam afforded the only means of access to the forestry in the
area to the west known as Priest's Hill.
6. Immediately
downstream of Paddock Pond there is a steep wooded gorge. A watercourse
connected Paddock Pond to the Dargle through this gorge. The confluence of the
watercourse and the Dargle is somewhat downstream of Powerscourt Waterfall. A
number of landmarks and features along the river, downstream of this point and
between it and the outskirts of the urban area of Bray, are of significance in
the history of the storm. The first is a bridge at the main entrance to
Powerscourt Waterfall, which was not damaged in the storm. A short distance
downstream a masonry bridge, which most of the witnesses have referred to as
Valclusa Bridge, was demolished by the current and pieces of masonry weighing
several tons were carried up to a hundred metres downstream. Further
downstream, at the confluence of the Dargle and its tributary the Glencree
River, Ballinagee Bridge was demolished. Further again downstream, roughly
halfway between Paddock Pond and the sea at Bray, at Tinnehinch Bridge near the
Golden Gates, the most dramatic incident recounted by an eye witness, which I
will outline later, occurred. Another tributary, the Glencullen River joins
the Dargle a short distance upstream of the bridge known as Dargle Bridge,
which was called Fassaroe Bridge by some of the witnesses.
7. Downstream
of Dargle Bridge the river flows through an area known as The Slang and it then
passes the factory premises of Lithographic Universal Limited, (the
Lithographic
premises) which are on the northern bank of the river. At the eastern boundary
of the Lithographic premises a steel bridge gave access to Killarney Glen on
the southern bank of the river. The steel bridge was swept away in the storm.
Below the Lithographic premises the river flows past a housing estate, the
Coburg Estate, built on low lying land on its northern bank. A short distance
downstream of the Coburg Estate, the river flows past the People's Park which
occupies the northern bank of the river from River Lane, which delimits the
western boundary of the People's Park, down to Bray Bridge. From River Lane to
Bray Bridge the People's Park is bounded on the south by the river from which
it is separated by a river wall. It is bounded on the north by a public road,
Lower Dargle Road. On the north side of Lower Dargle Road there are terraces
of houses. One such terrace, opposite the area of People's Park to the east of
the bandstand, is known as Vale Terrace. Another further east, is known as St.
Bridget's Terrace. The houses Nos. 1 and 2 St. Bridget's Terrace are at a
junction opposite the narrowest portion of the river, where there is a slight
bend in the river. This junction is known as Haughton's Junction. From
Haughton's Junction, Lower Dargle Road continues to the east to Bray Bridge,
Sheridans Lane (called Brabazon Cottages and St. Laurence's Terrace on the
Ordnance Survey map) leads in a north-easterly direction to Castle Street, and
Adelaide Villas leads in the direction of Greenpark Road.
8. From
River Lane east to Haughton's Junction, the People's Park is separated from
Lower Dargle Road by railings four feet high which are set in a plinth which
varies in height from nine inches to eighteen inches. From Haughton's Junction
to Bray Bridge, the People's Park, which tapers off very considerably going
from west to east, is separated from Lower Dargle Road by a masonry wall 1.2
metres to 1.3 metres in height.
9. From
the very considerable body of evidence adduced as to ground levels certain
broad propositions can be deduced. The lowest ground levels are in the area to
the north of Haughton's Junction along Adelaide Villas and Sheridans Lane. In
general, ground levels fall from the Coburg Estate east towards Bray Bridge;
Lower Dargle Road falls towards Sheridans Lane and Greenpark Road falls towards
Castle Street. To the east of Haughton's Junction Lower Dargle Road rises
towards Bray Bridge.
10. The
Plaintiff's store is part of a shopping complex near Bray Bridge at the
junction of Lower Dargle Road and Castle Street. The threshold level at the
entrance to the Plaintiff's store is 3.86m O.D. I should perhaps point out
that all levels mentioned later are expressed in meters over the Ordnance
Survey (Malin Head) datum. On the Castle Street frontage of the store there
are two carparks which, in general, are below the level of Castle Street. Near
its junction with Lower Dargle Road, Castle Street rises in the direction of
Bray Bridge.
11. Lower
Dargle Road and the area to the north of it, which is commonly known as Little
Bray, historically has been part of the natural flood plain of the Dargle.
12. Bray
Bridge is a three arched masonry bridge which gives access from Castle Street
to Main Street. At normal levels the river flows through the northern and
middle arches only. The southern arch has been variously described by the
witnesses as a "dry" arch, a "relief" arch and an "overflow" arch.
13. Downstream
of Bray Bridge, as it flows to the sea, the Dargle is bounded on the north by
Ravenswell Road, which in turn bounds Bray Golf Course. On the southern bank
of the river, some distance downstream of the bridge, there is a housing estate
known as Seapoint Court housing estate.
14. Overall
the Dargle catchment comprises 12,100 hectares. It is a very fast flashy
catchment, being very steep with very little storage.
15. The
dam at Paddock Pond was a gravity dam. It had two core elements. The main
core element was a pillar of blue clay, which was probably six feet wide at the
bottom and tapered off towards the top. The other core element, which was
masonry, also tapered off towards the top. Between the two core elements there
was ordinary earth fill and there was earth on the upstream and downstream
faces and on the top of the cores. A roadway was constructed on top of the
dam.
16. Four
witnesses who resided in the vicinity of Paddock Pond testified as to the use
and the condition of the roadway on the dam immediately prior to the storm.
Their evidence, which was not controverted, established that there was a
considerable intensification in the use of the roadway prior to the storm, when
it was traversed by large trucks and heavy machinery in connection with major
felling operations in the forestry on Priest's Hill. This led to a
deterioration of the surface of the dam, which dipped on the left hand side as
one looked downstream. Some weeks before the storm red slatey shale had been
spread across the dam, but this did not improve the surface. Mr William
McLaughlin (Mr McLaughlin), a Consulting Engineer called by the Plaintiff, was
of opinion that the traffic described by the witnesses was likely to have
caused damage to the dam, not merely the surface damage which the witnesses
observed, but also some breakdown of the structure beneath.
17. All
of the expert witnesses who addressed the issue of the failure of the dam were
agreed that it is impossible to say precisely what the failure mechanism was.
Mr McLaughlin thought that what happened was that the water over-topped the dam
at its lowest point - the dip observed by the local residents - and that this
would have led to erosion. The over-topping water would probably have cut into
the toe of the dam and this would have worked its way back and there would have
been a catastrophic movement of the majority of the material in the dam. Mr
Alan Kennedy (Mr Kennedy), the Managing Director of Nicholas O'Dwyer and
Partners, Consulting Engineers, who was called on behalf of Coillte, advanced a
somewhat similar theory. In his view, one could not expect the dam to be level
and a dip in the surface was to be expected. Initially as the water in the
reservoir rose it would have trickled over the lowest part of the dam and it
would have begun to gouge at the top downstream and tend to cut down into the
dam. As the quantity of water increased it would have begun to eat into the
bottom of the dam, and it would have damaged the bottom and undermined it
downstream. Once this happened, the dam would have, as it were, "hinged" open
and literally fallen over. Mr Kennedy was of the view that the eventual
failure would have been catastrophic and immediate. He emphasised that the
water flowing over the crest of the dam would not have had sufficient time to
affect the core.
18. At
the time of the storm, the only means in existence for releasing excess water
from Paddock Pond was a stone culvert constructed in the dam near the top of
the dam on its eastern side. In the past on the opposite side there had been a
pipe passing through the bottom of the dam with a contraption on the upstream
side for controlling flow into the pipe. By 1986 this contraption had been
defunct for many years. On the downstream side the pipe had been "deadheaded"
- capped off by a large bolt system.
19. On
the upstream side the culvert was the traditional rectangular shape with a
semi-circular top. While there is no reliable survey from 1986 which
establishes the dimensions of the culvert, I accept the evidence of Mr
Amhlaoibh O h'Aonghusa (Mr O h'Aonghusa), a Civil Engineer who was working in
the State forestry service in 1986, who calculated the dimensions of the
culvert on the basis of the photographic evidence which was adduced by the
Plaintiff as measuring 1.35m wide and 0.675m in depth as a reasonably fair
estimation of the dimensions of the culvert.
20. There
is reliable evidence as to the condition of the culvert before the storm from
one of the local residents, Mr Hugh Hackett (Mr Hackett). The culvert had
silted up with gravel and it was obstructed by vegetation and forestry debris.
Mr Hackett investigated the culvert on the downstream side a few weeks before
the storm and he discovered lengths of timber varying from 8 feet to 20 feet in
length which had obviously come through from the upstream side and had got
stuck at the exit and had become tightly enmeshed. Judging by the rot and
decay, some of the timber had been in the culvert for a considerable time. The
photographic evidence adduced by the Plaintiff of the condition of the culvert
after the storm corroborates this evidence. On the evidence, I am satisfied
that the culvert was capable of taking some overflow in its pre-storm condition
but that its capacity was considerably reduced because of the silting up and
obstruction by stones, vegetation and forestry debris. It follows that I
consider that it has not been established on the evidence that the location of
the culvert in relation to the lowest level of the dam was such to render the
culvert totally ineffective.
21. There
is no evidence that Coillte's predecessor had any scheme in place for the
periodic inspection of Paddock Pond and for the repair and maintenance of the
dam and the clearing and maintenance of the culvert or that any such
inspections or maintenance or repair works were implemented. On the contrary,
the only witness who was called who was in the employment of Coillte's
predecessor at the time was not aware of any such programme or activity.
22. The
drainage construction works which were being carried out in the vicinity of
Bray Bridge prior to the storm in August 1986 were being executed under the
Bray Sewage Scheme Stage II Contract Number 2A by Uniform for the Council. The
consulting Engineers in connection with the project were Messrs John B. Barry
and Partners (Barry). Mr Liam Prendiville, a Civil Engineer, was the resident
engineer in connection with the project and he was a temporary employee of the
Council. He was involved with the project for six or seven years. Mr Stephen
Ceillier, a Civil Engineer, was Uniform's site agent on the work at Bray. In
broads terms, the works involved the laying of a sewage pipeline from east to
west, extending from a point downstream of Bray Bridge along the southern bank
of the Dargle as far as Bray Bridge, then passing through the southern arch of
Bray Bridge and continuing along the southern bank for a short distance and
then crossing under the river and emerging on the north bank at a point
opposite the shopping complex in which the Plaintiff's store is located and
then continuing through the People's Park from east to west and crossing under
the river again near the western extremity of the People's Park. The works
also involved the construction of manholes to facilitate inspection and
maintenance of the pipeline at intervals along the pipeline. By August 1986
the pipeline had been brought within a short distance of the downstream (east)
side of Bray Bridge. A short distance upstream, to the west, of the bridge a
section of pipeline had been laid to the point of the river crossing and the
pipeline had been taken across under the river. On the northern bank the
pipeline was being laid in the People's Park. Immediately prior to the storm
in August 1986 the following works were ongoing: preparatory works for the
laying of the pipeline under the southern arch of the bridge; approximately
fifteen metres upstream of the bridge on the southern bank the construction of
a manhole; and on the other side of the river the laying of the pipeline in the
People's Park.
23. The
factual evidence to support the Plaintiff's allegation that the river defences
were breached in the course of the drainage construction works and that the
flow toward and through Bray Bridge was obstructed on the night of the storm by
reason of temporary works and machinery was supplied by Mr Ceillier and Mr
Prendiville, who had the benefit of some contemporaneous documentation, such as
site diaries, to aid recollection of what had occurred over ten years
previously.
24. In
relation to the allegation that the river defences had been breached, the
evidence establishes that a stretch of the river wall on the north side of the
river which had separated the river from the People's Park was taken down on
9th June, 1986 and had not been reinstated by 25th August, 1986. Mr
Prendiville's recollection was that the resulting breach was between five and
fifteen metres wide. Its location was the point at which the pipeline crossing
the river reached the northern bank of the river. It was necessary to take
down the river wall at this point because it had been built without foundations
and it was not possible to lay a pipeline under it while leaving it in situ.
At the time of the storm there was construction work outstanding in the area of
the breach and that work was not completed until the beginning of October 1986.
The only precaution which Uniform had taken to protect the breach was the
building of an earthen embankment within the People's Park. Neither Mr
Ceillier nor Mr Prendiville had any clear recollection of the location,
construction or dimensions of the embankment. It was obviously upstream of the
breach and Mr Prendiville's recollection was that it was built at right angles
to the river wall.
25. It
was not contended on behalf of the Plaintiff that the river wall should not
have been taken down to facilitate the laying of the pipeline but it was
contended that it should have been reinstated at the earliest opportunity. It
was also contended that a clay or earthen embankment was not a sufficient
barrier against a possible flood, pending reinstatement, because heavy rain and
water movement over an earthen embankment would remove it quickly. Mr.
McLaughlin stressed that the wall removed was part of the river defences and
that the location of the breach was one of the weakest points in the river
defences. His opinion was that a satisfactory temporary protection would have
been afforded there by sandbagging. Mr Liam Downes, who at the time of the
storm was the Civil Defence Officer for County Wicklow, testified that
sandbagging is only a protection against surface water and that it is not
effective against flooding.
26. The
evidence disclosed only two items of temporary works which would have impacted
on the flow of the Dargle on the night of the storm. The first was a temporary
road which had been constructed under the southern arch of the bridge to
facilitate movement of machinery from east to west in the course of the laying
of the pipeline. A photographic survey of the southern arch prior to the
construction works reveals that to some extent the southern bank of the river
extended under the southern arch. To create the temporary road Uniform
excavated the soft silty material and replaced it with suitable material such
as gravel from the river bed and some imported material. The resulting surface
was at a lower level than the level of the pre-existing bank which extended
under the southern arch, the lower level being necessary to create a depth
sufficient to allow a crane to travel under the arch. However, the temporary
road was wider, that is to say extended further north, than the pre-existing
embankment had. Mr. Prendiville's evidence was that the temporary road was
necessary to facilitate the drainage construction works. Mr. McLaughlin did
not seriously take issue with this proposition. However, he did make the point
that, if there was no further use for the temporary road, it should have been
removed. He also made the point that the silty sand which had been under the
southern arch prior to the construction of the road would have responded to the
flood more readily than the material with which it was replaced - larger and
more compacted material - allowing greater access for the flow through the
southern arch during the storm.
27. The
second item was trench sheeting which had been put in place immediately to the
west of the manhole which was under construction upstream of the bridge for the
purpose of retaining the soil during deep excavation of the trench or tunnel
for the pipe line.
29. The
construction works were "rained off" on 25th August, 1986. In the early
afternoon, having learnt that there was a weather warning, Mr. Cellier walked
the length of the works with the site engineer and took such precautions as he
considered necessary to secure the site and Uniform's plant and equipment. On
the evidence, I am satisfied that the largest and heaviest item of machinery
which was on site, an NCK/C 54 crane, was moved back out of the line of the
river. The only machine which was left on the upstream southern bank in the
line of the river was a Komatsu excavator, which was a "hired in" machine, and
for which Mr. Cellier did not have the keys and, accordingly, could not move.
At some time prior to the storm, in the course of the construction works, the
southern bank upstream of the bridge had been cleared of trees and vegetation
and had been benched back to facilitate the construction works. On the
afternoon of 25th August the Komatsu was tied to the benching.
30. Mr.
Cellier testified that following the storm there was debris in the northern
arch and the middle arch of the bridge. A large tree which had been caught in
the northern arch was subsequently removed by Uniform. However, there was no
debris in the southern arch after the storm.
31. Both
the NCK crane and the Komatsu excavator were silted up and had to be dug out
and cleaned. Nonetheless, I accept Mr. Ceillier's evidence that the crane was
moved on the afternoon of the 25th.
33. Mr.
McLaughlin expressed the view that the manner in which the works were executed
was substantially satisfactory, subject to the reservations he expressed in
relation to the temporary road, which I have already outlined. However, in his
view, once the river was in spate the direct flow to the south arch would have
been blocked by the presence of the Komatsu, the trench sheeting and the works
at the manhole.
34. One
of the ironies of this case is that one of the objectives underlying the
drainage project was to separate foul sewerage from surface water and storm
water drainage, there having been hitherto a combined system, in the Bray area
with a view to preventing or at least alleviating flooding in the Little Bray
area in the future.
35. The
Little Bray area had experienced flooding prior to 1986. There had been
flooding within living memory in November 1965 and there were records of severe
flooding in 1905, coincidentally on the 25th August in that year. However, the
storm, which was caused by an offshoot depression from "Hurricane Charlie",
which hit the Wicklow and Dublin areas on 25th August, 1986 was exceptional.
It occasioned publication by the meteorological service of a supplement to the
Monthly Weather Bulletin for August 1986. This publication from its opening
paragraph to its concluding paragraph paints a picture of a summer which is
best forgotten - a summer which was "a real wash out" with a thundery June, a
July which was the dullest in over thirty years and an August which brought a
succession of storms which caused flooding in many areas. Of Monday 25th
August, 1986 it records that in the worst affected areas the storm was of a
severity that would be expected only once in one hundred years on average and
it had the "depressing distinction" that no sunshine was recorded anywhere in
the country on that day.
36. That
gloomy picture is reflected in the rainfall records maintained by the
meteorological service. Over the twenty-four hour duration of the storm from
8.00 a.m. (0900 GMT) on 25th August to 8.00 a.m. (0900 GMT) on 26th August the
recorded rainfall in the Dargle and Upper Dodder catchments ranged from 80 mm
in low lying areas to at least 250 mm in the highest areas with a considerable
amount of the catchment which was located at middle levels recording 150 mm to
200 mm rainfall. At Bray Garda Station 86 mm was recorded during that
twenty-four hour period. Rainfall of that magnitude at a low lying station has
a return period of one hundred years. At Glenasmole, which is just outside the
Dargle catchment, 165 mm was recorded for the same twenty-four hour period,
with a return period of at least one hundred years. The one day values
recorded at Bray Garda Station and Glenasmole are put in perspective when
contrasted with the rainfall recorded at the same locations during the November
1965 storm. At Bray Garda Station the total rainfall recorded over three days
of the November 1965 storm was 48.7 mm and at Glenasmole 165 mm was recorded
over three days.
37. The
intensity of the rainfall on 25th August, 1986 was reflected in the rainfall
recorded at Casement Aerodrome where moderate to heavy rain persisted for most
of the twenty-four hour period commencing at 8.00 a.m., the highest six hour
duration total having occurred between 3.00 p.m. and 9.00 p.m. on the 25th and
the highest twelve hour duration total having commenced at around noon on the
25th. Although Casement Aerodrome is outside the Dargle catchment, Mr. Denis
Fitzgerald, the head of the Climatological Division of the Meteorological
Service, testified that the pattern of intensity represented by those records
would have been reflected throughout the Dublin and Wicklow area and was
consistent with the record at Glenasmole, where the total rainfall recorded for
the six hours from 5.00 p.m. to 11.00 p.m. on the 25th was 85 mm. For the sake
of clarity I should perhaps state that, although the Meteorological Service
records refer to G.M.T., the foregoing times are expressed as B.S.T..
39. Mr.
Fitzgerald, who did not strike me as a man given to hyperbole, resorted to
epithets such as "exceptional", "quite remarkable" and "startling" when
describing the recorded rainfall during the storm. Mr. Fitzgerald expressed
the opinion that in the extreme conditions which prevailed on 25th August the
actual rainfall could have been in the region of 10% higher than the recorded
rainfall.
40. The
overall picture which the data recorded by the meteorological service paints of
the storm on the 25th and 26th August, 1986 is of heavy persistent rain which
produced exceptional one day rainfall totals which, applying the methodology of
the Flood Studies Report, to which I will refer later, produced a return period
from one in fifty years to one in one hundred years. The rainfall was
accompanied by strong to gale force winds. The storm followed a number of
other active weather systems which affected Ireland and gave high rainfalls
earlier in the month. There was very little soil moisture deficit even in low
lying areas.
41. The
eyewitnesses whose experiences on the night of the storm I will record later
were unanimous that the storm was unprecedented in its ferocity. Between them
they had very many years of experience of living in the Dargle catchment and
none of them had previously experienced rain of such duration and intensity.
The level of the Dargle was higher on that night and its velocity greater than
had been experienced in living memory. In short, their perception of the event
was that it was a major natural disaster.
42. The
effects of the storm were not just localised in the Bray area. There was
evidence of very serious flooding in Dublin City when the Dodder overflowed its
banks flooding approximately three hundred and fifty houses, as well as public
houses and business premises from Milltown down to Ballsbridge. The rainfall
in the Dodder catchment during the storm was the most significant in recorded
history.
43. Throughout
Co. Wicklow, outside the Dargle and Dodder catchments, bridges were destroyed
or damaged during the storm. Annamore Bridge, an early 19 century masonry
bridge over the Avonmore was badly damaged. Avoca Bridge, a mid-19 century
bridge, on the Avonmore was badly damaged and, upstream of that, the Lions Arch
Bridge at Castlehoward, a masonry bridge, was completely destroyed. The Sally
Gap bridge high up in the Avonmore catchment was demolished. Ballyward Bridge,
a masonry bridge on the Liffey catchment upstream of the Blessington Lakes,
collapsed in early September 1986 as a consequence of damage sustained during
the storm.
44. In
summarising the eye-witness evidence of the flooding of the Dargle I will start
at Paddock Pond and follow the river down to Bray Harbour.
45. At
the time of the storm Mr. Hackett had been living in Paddock Lake Cottage for
four years. The stream which fed Paddock Pond passed his house. While, living
at a high altitude, he was accustomed to heavy rain, he had never experienced
rain of such intensity over such a protracted period as he experienced on 25th
August. At about 7.30 p.m or 8.00 p.m. that evening he noticed that the ground
outside his house became almost invisible. The water kept rising and rising
very steadily all evening. At about 9.00 p.m. it started to enter the house.
At about 10.20 p.m. the water just ran out of the house as if somebody pulled a
plug. Mr. Hackett attributed the departure of the water to the dam burst which
he became aware of the following day. However, the expert witnesses were
agreed that the departure of the water from Mr. Hackett's house was
attributable to the release of some local blockage, rather than the dam burst,
because of the relative levels of Mr. Hackett's house and Paddock Pond and the
dam.
46. Mr.
Ó hAonghusa gave a very graphic description of the gorge downstream of
the dam when he visited the area after the storm. He said that the erosion was
really spectacular. The water from the dam had attacked the glacial drift on
either side and cut huge clips in it thirty or forty feet high. It had tumbled
down big trees. It had scoured the gorge and the bottom of it was bare rock
which looked as if it was sandblasted. There was not a scrap of vegetation
left, no moss and nothing even in the crevices. Everything had been scoured
out. He had never seen rocks so well cleaned.
47. Mr.
McLaughlin, who had aerial photographs taken after the storm, interpreted the
aerial photographs as indicating that all of the channels and river sections
through which the Paddock Pond waters passed were more severely damaged than
the tributaries in the Dargle catchment, for example, the Glencree and
Glencullen rivers.
48. Moving
downstream past the confluence of the watercourse from Paddock Pond and the
River Dargle, Mr. John Hunt experienced the demolition of Valclusa Bridge. Mr.
Hunt's house is located beside a stretch of the Dargle between two bridges:
upstream is the bridge at the main entrance to Powerscourt Waterfall, which he
referred to as the Waterfall Bridge; and Valclusa Bridge is downstream. Mr.
Hunt had been living at this location since 1963 and his house had never been
flooded before the 25th August, 1986. Between 10.00 p.m. and 11.00 p.m. that
evening, he became concerned. He heard a very unusual noise outside, which he
believes was the sound of boulders coming down the river. When he
investigated, he saw water starting to come into his yard. He secured his
house and then went out to investigate further. He saw a lot of trees and
material coming down the river. At the Waterfall Bridge, the water was flowing
over the bridge and underneath it was completely swelled up. Water was coming
from every direction right around his house. It seemed to come in a "gush"
rather than a steady rise. It came into the house and, after about five or
seven minutes, it left the house again. When Mr. Hunt investigated, he
discovered that Valclusa Bridge was gone. The river was still very high.
49. Mr.
Forrestal, who was the County Engineer for County Wicklow at the time of the
storm, with responsibility for roads and bridges in the county, attributed the
collapse of Valclusa Bridge partly to the failure of the dam at Paddock Pond.
When the water from Paddock Pond came thundering down the valley, Valclusa
Bridge was carried clean away and pieces of masonry weighing several tons were
carried up to 100 metres downstream. Mr. Forrestal attributed the demolition
of Ballinagee Bridge further downstream also, in part, to the failure of the
dam at Paddock Pond.
50. Mr.
Paul Barnwell was in Enniskerry on the night of 25th August, 1986. While
endeavouring to find a safe route back to Bray, where he lived, he arrived at
the Golden Gates near Tinnehinch Bridge. Visibility was appalling. As he was
approaching Tinnehinch Bridge, there was a lot of water lying on the ground in
what he assumed was a dip in the road. There was a car ahead of him going in
the same direction. The car ahead proceeded through the water at a fairly slow
pace and got through. Having assessed that his own car had as good a chassis
clearance as the car ahead, Mr. Barnwell decided to drive through the water.
When he was approximately half way through, there was a sudden surge and the
car was lifted and appeared to shoot to the left hand side of the road. The
water began to come through at the side of the car. Then there was a sudden
major surge and the car was hit by a wall of water. The rear of the car swung
back and it appeared to drop down. The road had actually collapsed beneath the
car. Mr. Barnwell could not open the car door. The car was still in motion.
It was moving with the run of the water. Fortunately, he was able to open the
car window. At that stage, the water was up to window ledge level and, when he
opened the window, the water started coming into the car. He climbed out
through the window and clung to a tree. Eventually, his horrific experience
came to an end when he was rescued by a man on a tractor. Mr. Barnwell's
evidence was that initially when he drove through the flood, the water seemed
to be relatively still but after the surge the water was moving. He timed the
incident at between 10.30 p.m. and 11.00 p.m.
51. Moving
downstream again, Mr. Paul Kavanagh was working in the Lithographic premises
that night. Shortly after his shift finished, between 10.00 p.m. and 10.15
p.m., a Civil Defence officer advised the employees to leave the building. At
that stage, it was possible to see from the Lithographic premises, which were
directly on the north bank of the river, that the river was fairly high. Mr.
Kavanagh and a colleague drove to Main Street, Bray, to apprise the factory
manager of the position. As they drove along Lower Dargle Road, there was a
lot of water on the road, but Mr. Kavanagh could not say whether it was from
the river or from the shores (i.e. the drains). Because of the flooding on
Lower Dargle Road, they veered up Greenpark Road, via Pearse Road. There was a
lot of water along Greenpark Road - the depth of the water was well up to the
wheel of the car. They turned on to Castle Street at the Plaintiff's premises.
There was generally a lot of water around at the time, that is to say, between
10.15 p.m. and 10.30 p.m. Having collected the factory manager, they returned
to the Lithographic premises via Upper Dargle Road, which was not flooded.
They made slow progress around Castle Street. The water was rising all the
time and they noticed a certain amount of water in the Coburg Estate as they
went by. They got back to the Lithographic premises at about 10.30 p.m. to
find that, in their absence, the river had reached the wall of the Lithographic
premises and there was quite an amount of water in the yard, but not in the
factory premises. They started raising electrical equipment off the ground.
The water started to come in to the factory premises. They lifted shore covers
within the factory premises in the hope that the water would escape through the
shores. However, after a time, water was coming in and none was going out.
Waste bins which they had put against the back door were floating around. They
opened the back door. Forty gallon drums were floating around in the yard.
They closed the door and locked it. The next day, it was buckled. They stayed
in the factory premises for about forty-five minutes and left between 11.00
p.m. and 11.30 p.m. Mr. Kavanagh estimated that, at that stage, the water
level within the factory premises was over two feet. The electrical equipment
which had been raised was submerged.
52. Mr.
Bernard Collins lived in Killarney Glen across the river and a little
downstream of the Lithographic premises. At the time, vehicular and pedestrian
access to his property was via the steel bridge to the east of the Lithographic
premises. He was at home on the night of the storm. Between 10.30 p.m. and
10.45 p.m., his son came in with the news that the bridge had gone. Mr.
Collins went down to where the bridge had been. The banks on the southern side
of the river were starting to cave in and were going in stretches of ten to
fifteen feet at a time. The water was beginning to come up over the gabions.
At about 11.30 p.m., water had come into and was beginning to rise within the
house. When the front door was opened, a wall of water came in, like a tidal
wave, and ran ,via a thirty foot long hall, out the back door. It took three
members of the family to close the front door. There was about 3.5 feet to 4
feet of water outside the back door. The force of the water was horrendous.
The family decided to evacuate the house via the back door. The water was
waist high and for a distance of about thirty yards it was level. Thereafter,
the ground rose steeply up into the wood and the family escaped by that route.
Mr. Collins stayed around until about 3.00 a.m. or 4.00 a.m. on the 26th
August. The water had peaked by this time and was not rising anymore. The
expert opinion was that the demolition of the steel bridge was not related to
the arrival of the waters from Paddock Pond into Bray.
53. Mr.
Liam Doyle (Mr. Doyle), a Civil Engineer employed by Barry at the time surveyed
the River Dargle from Dargle Bridge down to Bray Harbour in the immediate
aftermath of the storm. He described the devastation along the banks of the
river from Dargle Bridge down to Mr. Collins' premises. At Riversdale House,
which is located about 3 km upstream of Bray Bridge, the northern bank was
severely eroded, a gravelled area around the house was destroyed by the flood
and there was extensive collapse of the lower bank, walling and pathway.
Further downstream, a masonry wall, part of the old river defences, had
collapsed. Upstream of the Slang, there was scouring on both sides and the
erosion by the flood was very severe and it was obvious that the river had
widened the channel. At the Slang on the northern bank, a three metre length
of footpath had disappeared into a hole on Upper Dargle Road. At the
Lithographic premises, which are located about 2 km upstream of Bray Bridge, a
river wall was undermined and a slab on which L.P.G. tanks were sitting was
cracked and had started to give way but, fortunately, the gas tanks had stayed
in position. The northern bank was severely eroded and an out-building, which
had been part of the Lithographic premises, was totally demolished. The
northern bank, opposite Mr. Collins' house, was severely eroded. In Mr.
Doyle's opinion, the scouring at this location was caused by the high
velocities caused by the restriction which the steel bridge presented before it
was swept away. The southern bank was severely eroded near Mr. Collins' house
and there was extremely severe scouring. A whole section of bank - four metres
or five metres long - had been scoured out by the river. The gabions were
damaged or destroyed on this stretch.
54. Of
the three residents of Lower Dargle Road who testified, Mr. Anthony Crinnion,
who at the time lived in Vale Terrace, lived furthest away from Bray Bridge.
At 9.30 p.m. on the night, Mr. Crinnion left his house to move his father's car
to higher ground. As he did so, he noticed a huge pool of water right outside
his door going down Pearse Road. Driving along Lower Dargle Road, he noticed
that water was surging up through the iron grids on the drains. In fact, it
was cascading out of the drains. A neighbour's car was on top of one of the
drains and the car was actually bouncing with the force of the water. Having
parked the car at Main Street, Mr. Crinnion walked home across Bray Bridge. He
noticed that a tree was stuck in one of the arches of the bridge, either the
northern arch or the middle arch, but probably the northern arch. When he
reached Maitland Street on the walk back, the water was about twelve inches
deep. The water was constantly rising slowly but, at some time between 11.00
p.m. and 11.30 p.m., there was a massive sudden upsurge in the level of the
water, which rose from what Mr. Crinnion described as "knee level" and "shin
level" to half way up the thigh and this rise occurred within three or four
minutes. The water continued to rise. At about 11.30 p.m., Mr. Crinnion's
family were concentrating on getting their possessions upstairs. Water had not
actually started to come into the ground level of the house because they had
blocked the door. Eventually, however, it started coming in through
ventilation blocks and in under the floors and was rising from that source.
About 12.20 a.m. on the 26th August, they decided to "throw" the master switch
and to go to bed. As he looked out from the first floor of his house on to
Lower Dargle Road at about that time, all Mr. Crinnion could see was the top of
the railings on his own wall and the spikes of the railings at the Peoples
Park. Everything else was submerged in water. The next morning, it was clear
that the maximum water level within the house had been about three to three and
a half feet but by then the water had totally receded.
55. Mr.
John Stirling lived at No. 2 St. Brigid's Terrace immediately to the west of
Haughton's Junction. After 9.00 p.m., he noted that water was flowing along
Lower Dargle Road and that it was flowing fairly fast into Brabazon Cottages.
He decided to move his caravan to higher ground and did so. When he was
returning home about 10.00 p.m., he was told by a Civil Defence officer that
Lower Dargle Road was impassable. Nonetheless, he persisted along Lower Dargle
Road and reached his home. At that stage, the water was flowing very fast. It
was probably about two feet high. He started sandbagging the entrance to his
house. While he was in the course of this operation, there was a sudden surge
and the sandbags collapsed. He made for the house but the water was ahead of
him. As he was climbing the stairs within the house, he thought the water was
not going to stop. It went up about six to six and a half steps of the stairs.
He timed the entry of the water into the house at around 11.00 p.m. but he was
unsure of the precise time. From his first floor window, he saw trees floating
down the river and possibly flowing down Lower Dargle Road. It was not
possible to distinguish between the river and the flood outside the river. He
observed that there was a fire engine parked at Haughton's Junction and it was
being lifted and it was hitting off the wall. It hit off the wall two or three
times and it seemed as if it was being forced around a corner. There were
people on the fire engine at that stage. They were subsequently rescued by
somebody who came along in an inflatable dinghy. Mr. Stirling said that the
main flow was going in the direction of Brabazon Cottages and St. Laurence's
Terrace.
56. Mr.
Vincent Eaves lived next door to Mr. Crinnion at No. 1 St. Brigid's Terrace.
Shortly after 9.00 p.m., Mr. Eaves crossed the Lower Dargle Road and he entered
the Peoples Park through temporary wooden gates immediately opposite Haughton's
Junction. He could hear the river, which was very loud. He walked across the
Park to the river wall and he could touch the water which was less than a foot
away from the top of the wall. When he turned to go back to his home, he
noticed that there was a lot of water further down the Park, that is to say to
the east, perhaps seventy feet away, which seemed to be flowing slowly up the
Park, i.e. westwards towards him. Mr. Eaves, in the course of his testimony,
indicated where the water stopped by reference to a map of Little Bray which
had been put in evidence. The point he indicated was the source of controversy
later during the hearing. I believe that Mr. Eaves pointed to an area within
the Peoples Park opposite No. 3 Dargleview Terrace. Although it was dark and
he could not see down towards the water, Mr Eaves' belief was that the water
was coming from the direction of the breach in the river wall in his direction.
When Mr. Eaves re-crossed Lower Dargle Road, there was only rainwater on the
road. Later, at about 9.45 p.m. or 10.00 p.m., he decided to go to the Boghall
Road to get sandbags. As he drove along Lower Dargle Road, there was a lot of
rainwater but he was able to drive. The round trip took him about twenty-five
minutes. When he got back home and stepped out of his van, the water on the
road had risen to just over the edge of his wellington boot below his knee,
which surprised him. He realised it would be futile to do sandbagging. He
went into the house and the water seemed to be rising fairly quickly. He
arranged for his family to move upstairs. Thereafter, the water rose to about
a foot. He then went upstairs himself. The water seemed to rise very quickly
and, in a short space of time, it rose from the first step of the stairs to the
fifth step of the stairs. The next day he measured the level of the water
inside the house at three feet nine inches. Mr. Eaves also observed the fire
tender. He saw it reversing down Adelaide Road and getting stuck with the
personnel on it. They could not get out because the water rose so quickly.
The boundary wall of his own house was submerged. He saw a neighbour's garden
seat floating pass. The flow was going in the direction of Brabazon Cottages
and the neighbour's garden seat went in that direction.
57. Two
of the eye witnesses were employees of the Plaintiff at the time of the storm.
Mr. John Garland was the security officer in the Plaintiff's store at Castle
Street. At 11.10 p.m. on the night of the storm, he was called to the store by
the cleaning staff and he arrived there at about 11.20 p.m. When he got there,
there were pools of water in the car park but he assumed that the pooling was
the result of falling rain. He dealt with the cleaning staff's problem and
left the store again about 11.35 p.m.. Mr. Garland testified that when he left
the store at 11.35 p.m. he did not notice any flooding in Castle Street and
there was no water within the store premises. However, he decided to return to
the store. He drove home and collected wet gear and he also collected his
colleague, Brian Flanagan. He returned to Main Street and parked his car in
Main Street. He made a phone call to the local radio station from a call-box
on Main Street and he went to the Civil Defence office nearby for information.
He then walked across Bray Bridge. The river was exceptionally high. He had
never seen it so high before. He looked across the parapet of the bridge into
the river. He could see the archways of the bridge. The water seemed to be
very high and very close to the top of the arches. He said the water was a
couple of feet from the top of the arches. Mr. Garland recollected that there
were briars and a tree trunk stuck in one of the arches and he believed that it
was the arch nearest to the Lower Dargle Road. There was flooding on the
Dublin side of Bray Bridge in Castle Street. He waded through water in the
shopping complex car park which was just below the level of his knees. When he
got to the Plaintiff's store, it was totally flooded. This was about 12.15
a.m. on the 26th. The level of the water within the store was about eighteen
inches and it subsequently rose to about twenty-four inches. He stayed in the
store overnight. At about 5.00 a.m., the water seemed to disappear out of the
store, but gradually, not instantly.
58. Mr.
Flanagan had been working in the store until 10.30 p.m. on the night of the
storm. He had walked home. As he crossed the car park of the shopping
complex, there were pools of water in the car park. As he crossed Bray Bridge
up into Main Street, the rain was falling heavily and the water was rising in
the river. He accompanied Mr. Garland back to the store later. When they got
to the car park, they had to wade through about eighteen inches of water. On
Castle Street, there was water to a height of two and a half to three feet.
When Mr. Garland opened the door of the store, the store was flooded. The
goods were floating around inside. The water was about twenty inches deep
inside. Over the space of the next two hours, the water rose by another six or
seven inches within the store. He also stayed in the store overnight. At
about 2.00 a.m., he went upstairs to the canteen which afforded a view out on
to Lower Dargle Road. The road was not visible: the water had come over the
wall and was about ten feet high outside the wall and it was continuing to flow
over the wall. The water levelled off within the store at about 3.00 a.m. or
4.00 a.m. and it started to subside at 5.00 a.m.
59. Mr.
Downes, in his capacity as a Civil Defence officer for County Wicklow, checked
the Lower Dargle Road at about 8.05 p.m.. At that time, water was coming
through the main drains in the middle of the road and there was about two
inches of water on the road. He checked the river and he considered it to be
well within safe parameters. While it was quite high, it was two or three feet
below wall level. At about 8.30 p.m., flooding was reported at the upper end
of Lower Dargle Road. A decision was made to monitor the situation and to start
evacuating people, if necessary. At around 9.50 p.m., the monitoring team
reported a rapid rise in the water level. A decision was made to open up
pre-designated centres for receiving evacuees. Between 10.00 p.m. and
midnight, the water had risen to a such a level that some of the Civil Defence
groups were cut off from direct contact with the Civil Defence headquarters.
The Lower Dargle Road had become impassable, even for four-wheel drive vehicles
which would normally drive through about two feet of water. It was decided
that vehicles were useless and boats from the local sailing club were organised
just after midnight. Evacuation by boat continued until 2.25 a.m. on the 26th
when a decision was made to withdraw the boats because one of them capsized.
60. Bray
Bridge was crucial to the Civil Defence operations that night and Mr. Downes
regularly checked the bridge visually to see whether there was a fall or rise
in the water. He said he had a good view looking over the parapet of the
bridge and he looked over at both sides - to the east and to the west. His
recollection was that there was water flowing through the southern arch and the
central arch. A tree was obstructing the northern arch. The flow through the
arches, with the exception of the northern arch, which was a bit restricted,
seemed to be consistent with the arches not being obstructed. He observed no
appreciable difference in the levels upstream and downstream. The water was
coming at great force. The bridge was vibrating as a result of the water
coming down. At one stage, the water appeared to him to be within two feet of
the top of the arches and it could have been higher.
61. The
Civil Defence log which was maintained on the night of the storm was produced.
I am satisfied that the log contains an accurate record of communications from
personnel working outside to headquarters. Of particular significance are the
entries in relation to the fire engine which was observed by Mr. Stirling and
Mr. Eaves. Three entries were made in relation to the fire engine. The first
recorded that at 11.25 p.m. the officer in charge of the fire engine reported
that the vehicle had become immobilised in six feet of water at Lower Dargle
Road. The log recorded that a Landrover had been despatched. The second entry
was made at 11.35 p.m. when it was recorded that the fire engine and crew were
still stranded. The final entry recorded that at 11.40 p.m. the fire officers
were told to abandon the vehicle. The log recorded that the vehicle was
abandoned.
62. Another
abandoned vehicle which Mr. Downes recalled was a Volkswagen Beetle which had
been parked in Castle Street opposite the Plaintiff's store. It was totally
submerged in water but from about 2.00 a.m. onwards it began to become visible
again and this was an indicator to the Civil Defence personnel that the water
was receding.
63. Of
the eye witnesses of the flooding in Bray on the night of the storm, it was
acknowledged by the expert witnesses that the most reliable observer was Mr.
Prendiville. Not only did he have a professional interest as the resident
engineer responsible for the drainage construction works, but on the night he
was called out by and accompanied by the late Mr. Kevin Conway, the Town
Engineer. Moreover, fortunately, Mr. Prendiville did not have to rely solely
on his memory when testifying as to the event which occurred more than ten
years previously; he had the benefit of his contemporaneous diary record and
report on the event. Mr. Prendiville was in Bray from 10.45 p.m. on the 25th
to 2.30 a.m. on the 26th and during that period he was observing the behaviour
of the river and its impact on the surrounding lands and buildings and he was
noting flood levels. The following is a chronological summary of Mr.
Prendiville's observations:-
64. Commenting
on the event, Mr. Prendiville described it as a natural disaster of enormous
proportions. His opinion was that, having regard to the immense amount of
water which ended up in the Little Bray area, the flooding of the Plaintiff's
premises was inevitable and, if a storm of the same magnitude were to be
visited on the Dargle catchment again, the same thing would happen
65. The
task which the Plaintiff assumed of establishing on the balance of
probabilities that the flooding of the Plaintiff's store was caused or
contributed to by factors other than the natural effects of the storm, namely,
the escape of water from the reservoir at Paddock Pond and the drainage
construction works in the River Dargle near Bray Bridge, was a formidable one
and the Plaintiff adopted an ingenious, if unusual, method of addressing the
issue. In the Spring of 1994, the Plaintiff commissioned H.R. Wallingford
Limited (formerly the Institute of Hydrology, a component of the Natural
Environment Research Council in the United Kingdom) to do a computer model of
the flooding of the Dargle catchment capable of simulating the effect on the
Plaintiff's store of -
66. This
work was carried out by Dr. Paul Samuels, a Chartered Civil Engineer and
Chartered Mathematician, with H.R. Wallingford Limited who specialises in
fluvial systems and computational hydraulics, with the assistance of Mr. James
Dent, the Principal Hydrologist with H.R. Wallingford Limited, in relation to
the meteorological input. Shortly after the storm, towards the end of
September 1986, Mr. McLaughlin had embarked on a study of the effects of the
storm on the Dargle catchment and some of the results of his surveys and
observations were utilised by Dr. Samuels.
67. Before
dealing with the evidence adduced by the Plaintiff on the causation issue,
namely, the evidence of Mr. McLaughlin, Mr. Dent and Dr. Samuels, a few general
observations are called for.
68. First,
it is clear from the evidence that the Plaintiff's instructions to Dr. Samuels
were that on the night of the storm there were two breaches in the river wall
in Little Bray, one being the breach opposite the shopping complex in which the
Plaintiff's store is located, and that that breach was represented as being
twenty-eight metres wide. Dr. Samuels was also instructed that the southern
arch of Bray Bridge was effectively blocked by temporary works and machinery.
At the hearing, it emerged that those instructions were incorrect. In fact,
there was only a breach in the river wall - the breach opposite the shopping
complex - and that breach, as created by Uniform, was between five and fifteen
metres wide. The only temporary construction within or underneath the southern
arch itself was the temporary road. As I have indicated above, the evidence
did establish the existence of the trench sheeting and the works at the manhole
and the Komatsu excavator on the southern bank upstream of the southern arch on
the night of the storm. The case made by the Plaintiff at the hearing, in the
light of these revelations, was that the access of the flow toward the southern
arch was obstructed.
69. Secondly,
the only "hard copy" generated by the computer which was put in evidence was an
isohyetal map, a connectivity diagram of the flow of the river from Powerscourt
Waterfall to the sea and a graph depicting the observed and simulated flood
levels at Little Bray. On my estimation, the duration of the oral testimony of
Mr. Dent and Dr. Samuels was just short of thirty hours. Not overlooking that
it emerged that the computer model had produced about five hundred megabytes of
information which was stored on compact disc, I venture to suggest that when
computer technology is employed as a probative tool, the information it
generates must be capable of presentation which is more conducive to more
efficient use of Court time. Insofar as there is a criticism implicit in this
observation, it is a criticism of all of the parties because it emerged at the
hearing that a suggestion from the Plaintiff's Solicitors to the other parties
that experts reports be exchanged was rebuffed.
70. There
are no flow gauges on the River Dargle and the experts who studied the effect
of the storm on the Dargle catchment were constrained to use diverse recognised
methods to quantify the peak discharge. Mr. McLaughlin, in his evidence,
suggested an approach and produced results which were at variance with the
results produced by the computer modelling. As I understand it, this aspect of
Mr. McLaughlin's evidence is not relied on by the Plaintiff. Mr. McLaughlin,
in the course of his study, surveyed the arches of Bray Bridge and took flood
levels at various points from east of Seapoint Estate to east of the
Lithographic premises. There was no controversy as to the accuracy of that
survey or the levels taken. Mr. McLaughlin also devised a chronology of the
journey of the waters released by the dam break from Paddock Pond to Bray
Bridge based on the eye witness accounts and all of the experts were in broad
agreement with his conclusion that the dam break occurred around 10.30 p.m. and
that the first of the flood waters arrived at Bray Bridge about an hour later.
However, the accuracy of the survey of Paddock Pond and of the calculation of
its capacity by Mr. McLaughlin was hotly disputed by Coillte.
71. It
is not disputed by Coillte that the water released by the failure of the dam at
Paddock Pond joined the Dargle upstream of Mr. Hunt's house and flowed with the
river down to Bray and into the Irish sea. What is in dispute is the volume of
water which was released by the dam failure and the timing and shape of its
arrival in Bray. In the years following the catastrophe, either Coillte or its
predecessor in title rebuilt the dam, but the evidence did not establish the
height of the rebuilt dam relative to the height of the dam which existed
before the breach. In the course of rebuilding the dam, the culvert was
destroyed and an alternative means of drainage was provided. Paddock Pond has
never refilled. Four different estimations of the quantity of water in Paddock
Pond before the breach were advanced, namely:-
72. On
the basis of the evidence, I have no difficulty in concluding that, in terms of
survey methodology employed, the survey carried out by Land Surveys (Lynwood)
Limited was the most accurate of the foregoing surveys but, unfortunately, it
is of no relevance because it represents Paddock Pond as it was in March 1994
and not Paddock Pond as it was at 10.00 p.m. on 25th August, 1986. Moreover,
both that survey and Mr. ÓhAonghusa's survey were to a local datum and
it is not possible to compare them to each other or to Mr. McLaughlin's survey
and, in particular, it is not possible to compare the crest levels adopted by
the respective surveyors. Mr. McLaughlin's surveying methodology has been
criticised, with justification, in my view. The upshot is that there is no
satisfactory evidence of the volume of water impounded in Paddock Pond prior to
the failure of the dam.
73. In
fulfilling the Plaintiff's commission, H.R. Wallingford Limited used two
established software packages. The first was the Micro F.S.R. model, which
embodies the calculations in the Flood Studies Report and later supplementary
reports, in particular, F.S.R. 16. The Flood Studies Report was originally
published in 1975. It was the result of investigations of methods of flood
estimation for engineering design purposes carried out under the aegis of the
Institute of Hydrology by that organisation and other organisations in the
United Kingdom with the co-operation of other organisations among them, the
Office of Public Works in this State. In simple terms, as I understand it, the
Micro F.S.R. model converts recorded rainfall over a catchment into river
discharge, which is the volumetric flow rate measured in cubic metres per
second (cumecs). The second was the Isis River model, which simulates the flow
of flood waters through a river system.
74. The
Micro F.S.R. model was used to ascertain the run-off response of the catchment
which, as I understand it, in simple terms means the percentage of the falling
rain that ends up in the river. The data inputted into the model was obtained
from the Meteorological Service and included hourly rainfall amounts and
durations at Dublin Airport and Casement Aerodrome, which were considered
important in assessing the distribution through time of the rainfall during the
storm. In ascertaining the percentage run-off, the catchment was divided into
seventeen sub-catchments. The run-off response, as indicated through the
model, lay between a range of 36% to above 70% for upper sub-catchments. The
average percentage run-off over the whole catchment was 62% and that translated
into an average rainfall depth of 141.6 millimetres over the whole catchment.
In terms of discharge, the result produced was a peak river flow at Bray of 220
cumecs, which result was inputted into the main model, the flow routing model.
75. The
dam break flood was modelled separately and the flow rate produced at the exit
of the gorge was also inputted into the main model. Dr. Samuels acknowledged
that in quantifying the volume of water impounded in Paddock Pond before the
flood, the greatest area of uncertainty related to the level of the crest of
the dam of which there was no reliable evidence. Taking the crest level from
Mr. McLaughlin's survey at 267.56m O.D., the impounded volume was 78,840 cubic
metres. It emerged through cross-examination that this volume represented not
only water up to crest level but it also included the depth of water flowing
over the crest to which depth 11,600 cubic metres were attributable. The
result produced by the model was that the flow through the breach in the dam
was 244 cumecs and after attenuation the discharge at the exit of the gorge was
204 cumecs. In the model, the dam break occurred at 10.35 p.m. and Paddock
Pond drained in fifteen to twenty minutes.
76. In
the model, the culvert was represented as a structure measuring two metres by
three metres and it was represented in the hydraulic code as a sluice. Two
positions were simulated: one with the culvert totally unobstructed and the
other with an opening of only 100 millimetres. The first position produced a
flow of three cumecs and the second position - the obstructed position - which
Dr. Samuels understood to reflect the reality on the night of the storm -
produced a flow of 0.4 cumecs.
77. The
main model represented the River Dargle from Powerscourt Waterfall down to the
Irish sea at Bray. The representation of the geography of the river channel in
the model was based on survey data produced by Apex Surveys Limited which
produced in excess of forty cross-sections of the river channel between
Powerscourt Waterfall and Bray, measurements taken by T.J. O'Connor &
Associates, Consulting Engineers, Mr. McLaughlin's survey of Bray Bridge and,
as regards the river section downstream of Bray Bridge, the 1 in 1,000 ordnance
survey map. All of the relevant topographical features were taken into
account, for instance, flows from tributaries, the collapse of Valclusa Bridge
and Ballinagee Bridge, transient flooding of the flood plains adjacent to the
river and suchlike.
78. I
did not understand any of the Defendants to disapprove of the manner in which
the geography and topography of the river was represented in the main model,
but they severely criticised the calibration of the main model, which, in broad
terms, means the assignment of values to the model parameters to match the real
situation being represented. In particular, there was criticism of the manner
in which values were assigned to the roughness coefficient (in hydrological
terminology, Manning's n), and the weir coefficients. The calibration data at
Dr. Samuels' disposal was Mr. McLaughlin's chronology of the journey out of the
Paddock Pond waters to Bray, Mr. McLaughlin's observed maximum water levels
from the Lithographic premises eastward, the eye witness observations of the
flooding, in the case of the flood plain, principally Mr. Garland's account.
In the calibration of the model which produced the results which I will record
later, Dr. Samuels assigned a value of 0.03 to Manning's n above the
Lithographic premises. He acknowledged that his visual observation of the
river upstream of the Lithographic premises would have suggested an appropriate
roughness coefficient of 0.04, but, having regard to the evidence of the actual
transit time of the Paddock Pond waters, he concluded that the model was
diffusing or attenuating the Paddock Pond waters more than had actually
happened and he reduced the river roughness to match up with the chronology.
The value assigned to Manning's n between the Lithographic premises and Bray
Bridge was 0.044 and downstream of Bray Bridge a value of 0.040 was assigned.
79. In
relation to the discharge coefficients for the weir flow over the river walls,
Dr. Samuels testified that experience over many years had indicated that where
there is flow over walls running parallel to a river, lower discharge
coefficients are necessary and the values assigned in the model were within the
range which he had used on other occasions.
80. It
is convenient to set out in tabular form the results produced by the model of
the maximum water level in the Plaintiff's store and the maximum flow at Bray
Bridge for the various scenarios which I have outlined above which H.R.
Wallingford Limited was commissioned to investigate and simulate. The results
summarised in the following table are predicated on the assumption that the
breach in the river wall created by Uniform was twenty-eight metres wide.
SCENARIO
|
MAXIMUM
WATER LEVEL IN PLAINTIFF'S STORE
(M.O.D.)
|
MAXIMUM
DISCHARGE AT BRAY BRIDGE
(CUMECS)
|
(i) Natural
Flood
|
3.72
|
220
|
(ii) Dam
break
|
3.94
|
240
|
(iii) Construction
Works
|
4.05
|
219
|
(iv) 1986
|
4.22
|
233.5
|
81. When
it emerged from Mr. Prendiville's evidence that the width of the breach was
somewhere between five metres and fifteen metres, the model was re-run and
produced the following maximum water levels in the Plaintiff's store for the
1986 scenario: in the case of a five metres breach, 4.05m O.D.; in the case of
a ten metre breach, 4.09m O.D.; and in the case of a fifteen metre breach,
4.13m O.D.
82. The
significance of the maximum water levels for the various scenarios produced by
the model was tested against the critical threshold at the Plaintiff's
premises, that is to say, the lowest level at which water could get in to the
Plaintiff's store from the St. Laurence's Terrace area at the onset of the
flooding, which, as I indicated at the outset, was 3.86m O.D. On the basis of
the tabulated figures -
83. However,
the result produced for scenario (iv) was considerably lower than the maximum
water level observed by the eye witnesses within the Plaintiff's premises,
which, in accordance with Mr. Garland's evidence, was in the region of 4.46m
O.D. and, according to Mr. Flanagan's evidence, was in the region of 4.55m O.D.
As I understand it, the highest water level within the Plaintiff's store which
the model simulated was 4.37m O.D. which was produced as a result of additional
sensitivity analyses carried out by Dr. Samuels during the course of his
cross-examination, which he was prompted to do because the water levels
produced when the width of the breach was reduced pushed the model results
further away from the eye witness observations. The figure of 4.37m O.D. was
based on a ten metre wide breach and a recalibration which assigned a value of
0.040 to Manning's n between the Lithographic premises and Bray Bridge and
assumed that storage within the built up area in Little Bray was only two
thirds of the maximum storage available, and corrected an incorrect linkage of
the flow path to Castle Street which was in the model originally. The level of
4.37m O.D. represented scenario (iv) and, similarly calibrated, the model
produced a level of 3.80m O.D. for scenario (i), which Dr. Samuels stressed was
still below the critical threshold of 3.86m O.D.
84. During
cross-examination, Dr. Samuels was asked to apportion the 0.3 metre rise in the
water level which, on the basis of the tabulated figures, the construction
works alone accounted for between the effect of the breach, on the one hand,
and the effect of the obstruction of flow to the southern arch, on the other
hand. He attributed 0.2 metre to the breach and 0.1 metre to the obstruction
of flow to the southern arch. However, he acknowledged that the figures have a
range of uncertainty associated with them, which he put at plus or minus 0.1
metre.
85. In
relation to the peak flow volumes which the model simulated, Dr. Samuels'
opinion was that attributing 20 cumecs to the Paddock Pond contribution by
comparing the result of scenario (i) with scenario (ii) was too low and that it
represented too much attenuation within the model. The Paddock Pond waters
contribution of 13.5 cumecs at Bray Bridge, indicated by a comparison of
scenario (i) and scenario (iv), represented the residual flow at Bray Bridge,
but the model produced a value of 30 cumecs for the Paddock Pond waters
contribution upstream at River Lane. Dr. Samuels acknowledged that there was a
margin of uncertainty in the range of plus or minus 15% in relation to the
assessment of the peak flows.
86. Bray
Bridge was represented in the model as having two arches only open and the
third totally obstructed. Although Dr. Samuels acknowledged that this was an
incorrect representation of the physical reality, nonetheless, he contended
that such representation was a proper representation within the model for
calibration purposes of the measured afflux at Bray Bridge, which he calculated
from Mr. McLaughlin's levels. In broad outline, Mr. McLaughlin had observed a
flood level of 3.70m O.D. fifty metres east of Bray Bridge and a level of 4.30m
O.D. forty-five metres west of Bray Bridge, the difference between the two
levels being 0.6 metre. Dr. Samuels adjusted this difference to 0.46 metres to
account for the slope of the river. On the basis of a maximum flow rate of
233.5 cumecs, using Yarnell's equations, he found that the difference in levels
which was 0.46 metre, was consistent with one third of the combined arch width
of Bray Bridge, as surveyed by Mr. McLaughlin, having been effectively lost.
Dr. Samuels attributed 0.15 metre of the measured afflux of 0.46 metre to
normal afflux. The balance, 0.3 metre, he attributed as to 0.1 metre to the
temporary road under the southern arch and as to the remaining 0.2 metre to the
other factors which obstructed flow to the southern arch and, in particular, to
the trench sheeting and the Komatsu excavator.
88. Dr.
Samuels' very considerable experience in interpreting eye witness accounts of
flood events was applied in calibrating the model. Moreover, that experience
enabled Dr. Samuels to suggest the proper inferences to be drawn from what was
observed by the eye witnesses. Dr. Samuels' interpretation of the evidence of
Mr. Crinnion, Mr. Stirling and Mr. Eaves as to the rapid rise in the water
level which they observed was that there was a sudden surge, which was entirely
consistent with the movement of an organised body of water down the river. The
only source of that body of water was Paddock Pond. Dr. Samuels rejected the
proposition that the established intensification of the rainfall over the
catchment in the previous six hours would account for the rapid rise in water
levels at Haughton's Junction around 11.30 p.m.
89. In
the course of his evidence, Dr. Samuels gave a broad picture of the course of
the flood as represented in the model and he elaborated on certain aspects of
it in the course of cross-examination. The following are some of the
significant points which emerged:-
90. Two
expert witnesses challenged the reliability of any conclusions drawn from the
simulations of the flood carried out by H.R. Wallingford Limited. Professor
Conleth Cunnane, the Professor of Hydrology at University College Galway, was
called on behalf of the Council and his evidence was adopted by Uniform. Dr.
Michael Bruen, a college lecturer in the Department of Civil Engineering at
University College Dublin, who specialises in hydrology, systems analysis and
computer methods, was called on behalf of Coillte.
91. Both
Professor Cunnane and Dr. Bruen questioned the suitability of the software for
the task for which it was employed by H.R. Wallingford Limited and they were
very critical of its application to determine the cause or causes of the
flooding in the Plaintiff's premises. The paucity of calibration data and the
lack of independent verification of the model's performance, in their view,
reduces one's confidence in the model.
92. In
relation to the Micro F.S.R. model, in broad terms, the main criticism was
that, while it is suitable for design purposes, it is not suitable for analysis
of a single past event. In consequence, its application to the storm and
flooding on 25th August, 1986 produced an under-estimation of the natural flood
discharge. The Flood Studies Report recommends that when reproducing recorded
events, the percentage run-off should vary with the catchment wetness index
within the event, as happens in nature, but the Micro F.S.R. programme does not
provide for this. The Flood Studies Report methodology, which embodies a
constant percentage run-off throughout the storm, was tested in the Flood
Studies Report itself and it was disclosed that it under-estimates peak flows
for severe events and over-estimates for minor events, which is a consequence
of the averaging inherent in the methodology. Dr. Bruen testified that, even
when properly used in the design situation, the Micro F.S.R. on average
under-estimates the peak where the percentage run-off is 60% or more by about
15%, reduced by 1.8% having regard to the modifications introduced in F.S.R. 16
and embodied in the programme. In the design situation, regard would be had to
these limitations of the Micro F.S.R. and a margin of safety would be built in.
93. Professor
Cunnane considered the average percentage run-off of 62% which Mr. Dent
calculated and the value of 220 cumecs which Dr. Samuels ascribed to the peak
discharge in the light of those limitations. His view was that having regard
to Mr. Fitzgerald's evidence of the weather before the storm, the retentive
capacity of the soil would have been minimal. The long persistent rain over
twelve hours on a catchment the size of the Dargle catchment would have
resulted in the soil being saturated early on and remaining so throughout the
storm. Mr. Dent's calculation of 62% was a design value, not an actual value,
and it was more likely exceeded. Professor Cunnane's opinion was that the
average percentage run-off would have been at least 70% and he would not rule
out 80%. Professor Cunnane estimated that, if the average percentage run-off
was 70% and if the percentage run-off was allowed to vary throughout the storm
in accordance with the catchment wetness index, a peak discharge of 303 cumecs
would have been produced.
94. The
criticisms of the Isis model focused on its application and, in particular, the
manner in which it was calibrated and the lack of verification. The
calibration runs were not able to produce the maximum water level observed in
the Plaintiff's premises by Mr. Garland and Mr. Flanagan. Therefore, Professor
Cunnane suggested one would have to be dubious about the applicability of the
model to the hypothetical situations - scenarios (i), (ii) and (iii), because
the outcomes for the hypothetical situations are limited by the fact that the
model in its calibration phase was unable to produce what actually occurred.
As to the Isis model's failure to produce the maximum water level observed in
the Plaintiff's premises, Professor Cunnane attributed this to one or other or
a combination of two factors: first, that insufficient water was allowed into
the model through the river channel from the catchment; and secondly, that the
mechanisms in the model for allowing water into the flood plain contributed to
the lack of water in the flood plain. In terms of volume, Professor Cunnane
estimated that the calibration run which produced a level of 4.22m O.D. in the
Plaintiff's premises was lacking about 20,000 cubic metres of water.
95. Professor
Cunnane contended that inappropriate values had been assigned to Manning's n in
the model and there was no objective justification for the values assigned. A
value of 0.044 was too high for the stretch from the Lithographic premises to
Bray Bridge and even a value of 0.040 was too high for the channel near the
Peoples Park. In Professor Cunnane's opinion, the values ascribed by Barry to
Manning's n, in its investigations after the storm, were more in keeping with
reality. Professor Cunnane illustrated the effect of adjusting the value of
Manning's n by the following example. If a value of 0.044 produces a discharge
value of 220 cumecs, assuming the water level remains the same, adjusting the
roughness coefficient to 0.033 increases the discharge value to 293 cumecs, by
approximately one third.
96. Professor
Cunnane's evidence suggested that a certain degree of scepticism should attend
making any deductions from a comparison of the model calculation of the maximum
level of the natural flood and the critical threshold level at the Plaintiff's
premises, given that the maximum water level produced by the model on a
calibration run (4.37m O.D.) was less than the maximum observed water level,
from which it might be concluded that the maximum water levels produced for
scenarios (i), (ii) and (iii) were under-calculated. The need for scepticism
was underscored by the following illustrations:-
97. Professor
Cunnane disputed Dr. Samuels' calculation of the afflux at Bray Bridge at 0.46
metre. He produced results of 0.3 metre and 0.32 metre on calculating the
afflux by two different methods. He explained that every bridge provides some
form of constriction which causes some measure of afflux upstream. In the case
of Bray Bridge, which has a total water way width of 27.8 metres for a river
which upstream of the bridge widens to a width of 39 metres or 40 metres, a
fairly severe constriction is presented by the bridge. On his calculation,
with a flow of 250/260 cumecs, an afflux of 0.32 metre would be entirely
attributable to natural processes - the constriction created by the piers and
the abutments of the bridge alone.
98. Professor
Cunnane assessed the factors which the Plaintiff alleges contributed to the
afflux individually and in combination and expressed the following opinions:-
99. Professor
Cunnane analysed the significance of the breach in the river wall in the light
of the eye witness accounts. Because of the existence of the earthen
embankment, water coming through the breach would have flowed in an easterly
direction first, filling the space between the embankment and the steps at Bray
Bridge. It would have only gone in a westerly direction when the water level
in the river reached a height a little above the top of the embankment. Mr.
Prendiville's evidence was that the embankment was scaled by 10.45 p.m.
However, on the basis of Mr. Prendiville's evidence that the area of the
Peoples Park between the temporary gates at Haughton's Junction and the river
wall opposite the gates was not flooded at that time, the inference to be drawn
is that the water had not reached this part of Peoples Park, insofar as it was
travelling west at this time. The record of the fate of the fire engine and
its occupants establishes that between 11.30 p.m. and 11.45 p.m. the water had
reached a level of 4.75m O.D. at Haughton's Junction. The highest flood level
which Mr. McLaughlin recorded opposite the breach was 4.4m O.D.. Professor
Cunnane inferred that by this time water must have been flowing from Haughton's
Junction towards the breach and back into the river. His deduction as to the
effect of the breach from the facts was that water could only have been flowing
from the breach westerly in the direction of Haughton's Junction from
approximately 10.45 p.m. to 11.30 p.m./11.45 p.m. and he concluded that the
breach played a very limited, if any, role in the flooding of the Haughton's
Junction area and it would have had a minimal effect on the Plaintiff's
premises. If there had been no breach, in Professor Cunnane's opinion, the
Plaintiff's premises would have been flooded. Indeed, he suggested that the
breach had an ameliorating effect in that from midnight onwards, when the water
was still rising, the flow was going back into the river channel through the
breach.
100. Professor
Cunnane expressed the view that the Plaintiff's premises would have been
flooded by the natural flood even if it had not been augmented by the waters
from Paddock Pond. In his view, the volume of water required to inundate the
Plaintiff's premises was available in the natural flood and he contrasted the
volume of water impounded behind the dam in Paddock Pond, whether it was 45,000
cubic metres or 80,000 cubic metres, with the quantum of rain which fell on the
catchment during the storm, which he estimated at 16,000,000 cubic metres.
101. Although
Dr. Bruen did not comment in any great detail on the Isis model, he did
challenge the reliability of the results it produced having regard to the
limited data for calibration and the lack of verification. While he
acknowledged that the Isis model has a very good reputation, a particular
weakness in its application which he adverted to was that it was infected, as
it were, by the deficiencies in the Micro F.S.R. model which resulted in the
modelling exercise not producing a reliable estimate of the peak discharge
during the storm. That the modelling exercise did not replicate the timing of
the peak of the flood as observed by the eye witnesses impressed Dr. Bruen and
confirmed his view of the unreliability of the results of the modelling
exercise. Acknowledging that he was not in a position to say that the Paddock
Pond waters had no effect on the flooding of the Plaintiff's premises, he
expressed the view that it had no significant effect, the determining factor in
his conclusion being the time lapse between the arrival of the waters from
Paddock Pond into Bray, which was reasonably well fixed by the evidence, and
the peak of the flood as observed by the eye witnesses and, in particular, Mr.
Prendiville.
102. As
I have indicated above, one of the factors which Professor Cunnane perceived as
being responsible for the failure of the model to produce the maximum water
level observed in the Plaintiff's premises was the manner in which the linkages
between the flow in the river channel and the flow on the flood plain were
treated in the model. Professor Cunnane's criticism of the treatment of the
linkages was not merely that it resulted in the model producing too little
water on the flood plain, but that it undermined the integrity of the modelling
exercise. Weir coefficients were used to allow water to transfer from the
river channel on to the flood plain. Flow over weirs has been understood for
one hundred years and the weir coefficients are based on a fortiori hydraulic
knowledge. Yet, in the modelling exercise, they were allowed to be adjusted in
the calibration process. This was not necessary and should not have happened.
Professor Cunnane also disapproved of the modelling procedure whereby the weir
coefficients were allowed to interact with the value assigned to Manning's n
for the channel. He could not understand why something that is physical in the
channel, that is effectively the measure of the resistance of the channel to
flow, should be allowed to vary while one is also varying the weir
coefficients. In his view, this kind of "linking" is not satisfactory in a
case where one is trying to prove an effect. The gravamen of Professor
Cunnane's criticism was that instead of using hydrodynamic equations to
calculate the flow rate from the river on to the flood plain, a subjective
approach was adopted, which is not a suitable basis for demonstrating or
proving that something has happened.
103. In
summarising the eye witness accounts above, I have recounted Mr. Doyle's
observations of the impact of the flood on the river channel from Dargle Bridge
downstream two or three days after the storm. These observations were the
start of an extensive survey of the river channel and the flood defences
carried out by Barry following the storm. The survey lasted three months.
104. Following
the flooding of Little Bray in 1965, Barry had carried out an extensive survey
of the Dargle with a view to designing the river channel to take a flow of 200
cumecs. The design was implemented in 1969 when the channel itself was
re-graded by dredging, a weir in the vicinity of Country Brook was removed and
the river wall was underpinned as necessary. Following the post-1986 survey,
Barry calculated the peak flow in the channel between Dargle Bridge and the
Slang on the night of the 1986 storm at 285 cumecs using -
105. With
the aid of the Office of Public Works computer, Barry also did flow profiling
of the flood, inputting the same material into the computer. Various
discharges were investigated, to as high as 320 cumecs and consistency with the
flood marks was found. Barry's conclusion was that a flood in the order of
magnitude of 300 cumecs had occurred in a channel which had capacity to carry
in the region of 200 cumecs.
106. Using
the Flood Studies Report methodology, Barry concluded that a flood with a
return period in excess of one in one hundred years occurred in the Dargle
catchment on the 25th/26th August, 1986.
107. Mr.
Doyle's interpretation of what occurred on the night of the 25th was that the
river stayed within its banks between Dargle Bridge and the Slang; that a flow
of in excess of 285 cumecs came down fully contained within that stretch.
However, from that point down, there was not the capacity to retain it totally
within the channel and it spread on the right bank and on the left bank, coming
out on the right bank at Mr. Collins' house and on the left bank at the
Lithographic premises. It flowed through the Coburg Estate. The flow of in
excess of 285 cumecs was trying to come down the river but was not finding
adequate capacity in the main channel. So it over-topped the river wall and
flowed through the Coburg Estate and down into Little Bray.
108. In
the course of Mr. Doyle's evidence, two maps were produced which gave a
striking picture of Little Bray on the night of the storm. On one, Mr. Doyle
had denoted with shading the extent of the area flooded. It came as no
surprise when Mr. Doyle testified that 520 properties in all were flooded in
the Dargle catchment. On the other map, Mr. Doyle had indicated the maximum
depth of water above street level at various locations, which showed levels as
high as 1.5 metres at Haughton's Junction and at the northern end of Fairgreen
Road and as high as 1.6 metres at the northern end of Adelaide Villas. On this
map, Mr. Doyle had also indicated the peak flood level relative to the height
of the river wall along the Peoples Park, which demonstrated that, apart from a
relatively short stretch of about ninety metres roughly opposite the bandstand,
the entire river wall must have been over-topped.
109. Barry
also analysed the contribution of the Paddock Pond waters to the flooding in
Bray. Their assessment of the Paddock Pond waters contribution to the peak
flow in Bray was that it fell within the range of 28.5 to 42.5 cumecs. Their
conclusion was that, while the Paddock Pond waters were a definite factor in
the flooding at Bray, in the overall context of the duration of the flood and
the levels achieved and when they were achieved, they were not a significant
factor. In short, had there been no dam break, the Plaintiff's premises would
have been flooded in any event by the natural flood. The duration of the flood
and the fact that the waters kept rising until some time after 2.00 a.m. on the
26th supported that conclusion, it was contended.
110. In
relation to the evidence of Mr. Crinnion, Mr. Stirling and Mr. Eaves of a
sudden rise in the water levels, Mr. Doyle's interpretation was that it was the
result of the over-topping of a significant extent of the river wall along the
Peoples Park, which in turn was the result of the water in the channel rising
at a steady rate to a point where it suddenly started discharging over the
river wall.
111. In
relation to the assessment of the peak flow on the outskirts of the urban area
of Bray, there was a large measure of conformity between Mr. Doyle's evidence
and the evidence of Mr. Kennedy, whose firm had been retained by Coillte in
connection with this litigation to investigate the contribution, if any, of the
collapse of the dam to the flooding of the Plaintiff's premises. Mr. Kennedy's
calculation of the peak flow at a point just downstream of the confluence of
the last tributary to join the Dargle, which flows from the Scalp, was 310
cumecs or 341 cumecs depending on whether he assigned a value of 0.040 or 0.035
to Manning's n. His opinion was that 310 cumecs represented the proper
discharge. He also calculated the contribution of the waters from Paddock Pond
within that figure on the basis of the rainfall recorded at Glenasmole,
assuming a percentage run-off of 70%, which put the contribution at 29 cumecs.
Mr. Kennedy also calculated the discharge between the dam and the location at
which the watercourse from Paddock Pond joins the Dargle and came up with
figures of 187 cumecs and 210 cumecs depending on whether he assigned a value
of 0.045 or 0.040 to Manning's n. Apart from a rainfall contribution, which
Mr. Kennedy calculated at nine cumecs, these figures represented only the
waters from Paddock Pond. Mr. Kennedy's conclusion was that there was
considerable attenuation of the Paddock Pond flood when it reached Bray.
112. Mr.
Kennedy's interpretation of the flooding process coincided with that of Mr.
Doyle. In his opinion, the peak flow coming down the river was in excess of
300 cumecs and, as the river channel had a carrying capacity of only 200
cumecs, flooding was inevitable. The peak flow was 50% in excess of the
channel capacity and it was inevitable that it would over-top the river wall.
Mr. Kennedy acknowledged that water from Paddock Pond did come down into Bray
and did contribute to the flooding.
113. However,
Mr. Kennedy was not persuaded by the eye witness accounts that there was a
distinguishable surge attributable to the Paddock Pond waters. His view was
that if there had been a surge in the river it would have been noted by Mr.
Prendiville. He explained that the Paddock Pond flood did not "piggy-back" on
the natural flood; it was subsumed into the natural flood so as not to be
noticeable. Mr. Kennedy stressed that rainfall can give rise to a sudden rise
in water level - to a surge. He testified that, if the Paddock Pond waters
were solely responsible for the over-topping of the river wall at the Peoples
Park one would have expected the water level of the river to rise, then the
wall to be over-topped and, when the Paddock Pond flood had gone through Bray,
for the level to settle back to a lesser level. However, the evidence of the
eye witnesses was that the water continued to rise and rise long after the
Paddock Pond flood had arrived and he concluded that the Paddock Pond
contribution was obscured or totally overtaken by the natural flood. He
calculated that it took the Paddock Pond flood about an hour to pass through
Bray but he acknowledged that that calculation assumed a linear rate of passage
rather than an exponential rate which would have occurred in reality and he
conceded that the passage would have taken longer. Nonetheless, he stood by
his thesis because, on the evidence, the peak flood occurred at 2.10 a.m.
114. Mr.
Kennedy took issue with some of the propositions advanced by Dr. Samuels as to
what occurred at Paddock Pond. First, he rejected Dr. Samuels' proposition
that an earthen dam could have sustained a flow above crest level for long
enough to create a head of 300 millimetres over the width of the dam, which is
what Dr. Samuels' volume of 11,600 cubic metres represented. While Mr. Kennedy
did not quibble with Dr. Samuels' calculation of the head, his view was that,
given that the dam was an earthen dam, what Dr. Samuels had envisaged happening
could not happen physically. Secondly, in Mr. Kennedy's opinion, even if the
culvert had been operating effectively, the dam would still have failed. On
the basis of the eighty-five millimetres of rain recorded at Glenasmole over
six hours, he calculated that the inflow into Paddock Pond was four cumecs,
whereas the capacity of the culvert was one cumec only, leaving three cumecs of
inflow to pass over the dam, with inevitable failure.
115. Having
outlined the evidence, I now propose considering the issues which arise between
the parties, namely:-
116. It
was submitted by Mr McCullough, on behalf of the Council, that, as the sanitary
authority for the Bray area, it was under a statutory duty, by virtue of
Section 17 of the Public Health (Ireland) Act, 1878, to cause to be made such
sewers as might be necessary for effectually draining the Bray area and that on
August 25th, 1986 the drainage construction works being carried out in the
Dargle at Bray were being executed in pursuance of that duty and in the only
manner in which they could reasonably be executed. That being the case, it was
submitted, as a matter of law, the Council is immune from an action based on
nuisance and is free from liability unless it was negligent in the exercise of
its statutory duty and power. I am satisfied that this proposition is correct
and that, in the absence of proof of negligence, no liability attaches to the
Council or to Uniform, which executed the works under contract with the Council.
117. The
Council and Uniform are charged with the same acts and omissions in the
implementation of the drainage construction works as constituting negligence,
the claim against the Council being premised on the fact that it planned and
directed the works, and the claim against Uniform being premised on the fact
that it executed the works under contract with the Council. The only matters
which emerged from the evidence on which the Plaintiff could found an
allegation of negligence against the Council and Uniform were:
118. It
was urged by Mr McCullough on behalf of the Council that, in determining
whether the Council or Uniform was negligent, the Court should judge the
conduct of these Defendants in the context in which they were implementing the
works and, in particular, the Court should have regard to the absolute
necessity to implement the sewage scheme in Bray and to the fact that there was
no evidence that there was any better or safer way of executing the works.
Moreover, it was urged by Mr McCullough that in determining whether these
Defendants are liable for the consequences of their conduct, the essential
issue is whether those consequences were reasonably foreseeable by them prior
to the storm, the contention being that they were not.
119. Mr
Comyn, on behalf of the Plaintiff, submitted that the correct test on the issue
of foreseeability is the test to be extrapolated from the following passage of
the Judgment of Walsh J. in
Kelly
v. The Board of Governors of St. Lawrence's Hospital
[1988] IR 402 (a jury action involving an allegation of negligence against a
hospital in connection with the custodial care of a patient suffering from
epilepsy and some automatism) at page 410:-
120. The
criterion is whether the type of damage done, rather than its extent, is
foreseeable, it was submitted. Mr. Comyn pointed to the flashy nature of the
river, the previous experience of flooding in the Little Bray area and the
evidence as to the vulnerable nature of the river flood defences at the
location of the breach. He acknowledged however, that as regards the standard
of care expected of a public authority carrying out public works, the Courts
allow a margin of tolerance.
121. In
my view, neither the Council nor Uniform fell short of the standard of care
which they owed to riparians in Little Bray. As I am entitled to, I have had
regard to the social utility of the conduct of these Defendants and the object
of the works - to improve drainage in the Bray area. While a storm of
sufficient ferocity to raise the level of the river sufficiently to flood
riparian lands was, in my view, a foreseeable possibility, it was a very remote
possibility, particularly, as within the previous twenty years the river
channel had been upgraded following the 1965 flood to accommodate a 200 cumec
flood, at the behest of the Council and following an intensive study by the
consulting engineers involved in the sewage project. I have no doubt that the
standard of care observed by the Council and Uniform was commensurate with the
degree of possibility of flooding and that it conformed with the standard to be
expected from a reasonable sanitary authority and a reasonable building
contractor in the circumstances which prevailed. My observations in relation
to the specific allegations of negligence against these Defendants are as
follows:
123. I
have outlined in some detail the evidence as to the condition of Paddock Pond
immediately prior to the storm. There was uncontroverted evidence that the
surface of the roadway which traversed the dam was in poor condition
immediately prior to the storm. I am satisfied, on the evidence, that the
deterioration of the roadway was attributable to intensification of its use in
connection with the forestry operations in Priest's Wood and the failure of
Coillte's predecessor to have a proper care and maintenance programme in place
in relation to Paddock Pond and its failure to adequately respond to the
deterioration and lack of repair of the surface of the dam. I am also
satisfied that it was Coillte's predecessor's failure to have a proper care and
maintenance programme in place and to act in accordance with it which led to
the capacity of the culvert being considerably reduced because of silting up
and obstruction by stones, vegetation and forestry debris, as I have already
found, on the night of the storm. The evidence discloses a deplorable lack of
care and concern on the part of Coillte's predecessor as the owner, occupier
and body responsible for Paddock Pond.
124. It
is common case that the dam at Paddock Pond collapsed at around 10.30 pm on the
night of 25th August and that thereupon the water impounded behind the dam
escaped, rushed down the gorge and joined the waters of the Dargle. The
crucial question is whether Coillte's predecessor's conduct in permitting the
intensification of the use of the road on the dam, failing to adequately
maintain the surface of the dam and failing to maintain and keep clear from
obstruction the culvert, was a material element and a substantial factor in
bringing about the dam failure.
125. In
my view, the Plaintiff has not established on the balance of probabilities a
causal link between the use and lack of proper maintenance of the dam prior to
the storm and to the dam failure. In particular, the evidence of Mr
McLaughlin, considered in the light of the theories advanced by its experts as
to the manner in which the dam burst, was not sufficiently cogent to lead me to
conclude that the traffic on the dam resulted in structural effects on the core
which were of significance in the subsequent failure of the dam or that the
condition of the surface facilitated erosion such as to be a material element
in the failure mechanism. I consider that the proper inference to be drawn
from the evidence is that it was the effect of the enormous volume of water
flowing over the crest of the dam at the height of the storm which caused the
failure. Mr Kennedy's theory as to the failure mechanism, in my view, is
consistent with the photographic evidence of the condition of the dam in the
immediate aftermath of the storm, from which it appears that the core was
undamaged.
126. That
inference leads to the question of whether the obstruction of the culvert was a
material element and a substantial factor in the increase in the level of the
water impounded behind the dam, eventually to a level at which it overtopped
the dam. It is impossible, on the evidence, to quantify the diminution in the
outflow through the culvert caused by the obstruction or to relate that
diminution to the inflow into Paddock Pond with any degree of accuracy. Dr
Samuels, on the basis of the assumptions embodied in the model as to the
dimensions of the culvert and its effective unobstructed capacity, quantified
the reduction in discharge as a reduction from 3 cumecs to 0.4 cumec. However,
I am not satisfied that either assumption reflected the reality on the night.
Mr Kennedy calculated the discharge capacity of the culvert in its unobstructed
state at 1 cumec and the inflow into Paddock Pond at 4 cumecs. If these
calculations were based on data which reflected the reality on the night, the
obstruction of the culvert could not have been a material element or a
substantial factor in the volume of water which was inevitably going to flow
over the dam. Of course Mr. Kennedy's estimation may be no more an accurate
reflection of what happened on the night than Dr. Samuel's.
127. Having
regard to the evidence as a whole, in my view, it was the unprecedented
intensity and duration of the storm and, in particular, the extraordinary
degree of precipitation in the upland area of the Dargle catchment in the five
to six hours before 10.30 p.m. on the 25th which caused the water in Paddock
Pond to rise and rise and, even if the culvert had been wholly unobstructed,
the culvert could not have played an appreciable role in keeping down the level
of the water. It follows that the blockage of the culvert was not a material
element or a substantial factor in bringing about the dam failure.
129. The
most frequently quoted statement of the rule in
Rylands
-v- Fletcher
is
the following passage from the judgment of Blackburn J. in the Court of
Exchequer Chamber [(1866) L.R.1 Ex. 265] :-
130. The
judgment of Blackburn J. was subsequently approved by the House of Lords (L.R.
3 H.L. 330), although in his speech Lord Cairns restricted the application of
the rule to circumstances where there had been "a non-natural use" of the land
by the defendant. The decision in
Rylands
-v- Fletcher
itself is authority for the proposition that the creation of an artificial lake
or reservoir is a non-natural use. The nature of the liability of a defendant
for the escape of dangerous things has been clarified recently by the House of
Lords in
Cambridge
Water Company Limited -v- Eastern Counties Leather Plc.
(1994) 2 AC 264 in which it was held that forseeablility of harm of the
relevant type by the defendant is a prerequisite of the recovery of damages
both in nuisance and under the rule in
Rylands
-v- Fletcher
.
In the light of that decision the nature of the liability of a defendant under
the rule in
Rylands
-v- Fletcher
is
summarised as follows in
Charlesworth
and Percy
on
Negligence,
9th Edition, at page 893:-
131. In
my view, Coillte could reasonably have foreseen that, if the dam at Paddock
Pond failed and the impounded water escaped, it would flow via the gorge and
the watercourse into the Dargle and that damage in the nature of flooding of
the riparian properties downstream would ensue. In my view, the circumstances
of the escape of water from Paddock Pond on the night of 25th August, 1986 come
fairly and squarely within the ambit of the rule in
Rylands
-v- Fletcher
and, unless Coillte has established one of the excusing factors recognised as
constituting a defence to liability under that rule, Coillte is liable to the
Plaintiff provided the Plaintiff has established that the flooding of its
premises was caused or contributed to by the water from Paddock Pond.
132. The
defence which Coillte claims absolves it from liability is act of God. Mr.
Keane, on behalf of Coillte, relied on
Nichols
-v- Marsland
(1876) 2 ExD 1, which is described in McMahon and Binchy on
Irish
Law of Torts
,
2nd Edition, at page 491 as the only reported decision in which the defence of
Act of God has been successful, in support of his contention that the dam
failure was caused by act of God. The facts in that case, as set out in the
judgment of Mellish, L.J., were that the defendant was the owner of a series of
artificial ornamental lakes, which had existed for a great number of years, and
had never previous to 18th June, 1872 caused any damage. On that day, however,
after a most unusual fall of rain, the lakes overflowed, the dams at their end
gave way, and the water out of the lakes carried away the county bridges lower
downstream. The jury found that there was no negligence either in the
construction or the maintenance of the reservoirs, but that, if the flood could
have been anticipated, the effect might have been prevented. Mellish, L.J.
distinguished the case before him on the facts from
Rylands
-v- Fletcher
stating:-
133. Having
stated that the opinion of the Court of Appeal was that the defendant was
entitled to excuse herself by proving that the water escaped through the act of
God, Mellish, L.J. went on to say:-
134. Mr.
Keane emphasised the similarity on the facts of
Nichols
-v- Marsland
and the instant case and urged that
Nichols
-v- Marsland
should
be followed. He submitted that the decision of O'Hanlon J. in
Dockeray
& Another -v- Manor Park Homebuilders Limited
,
in which a reserved judgment was delivered on 10th April, 1995, the only recent
Irish authority in which the defence of act of God in a similar context to this
case was considered, is distinguishable on the facts. Having recognised that
act of God or vis major could, in appropriate circumstances, afford a defence
to a claim under the rule in
Rylands
-v- Fletcher
,
and having quoted a passage from McMahon and Binchy at page 492 to the effect
that it would appear that "only the most extreme of natural phenomena" will
afford a good defence, O'Hanlon J. went on to say:-
135. Mr.
Comyn's response to Mr. Keane's submission was that in
Greenock
Corporation -v- Caledonian Railway
(1917) AC 556 the finding of fact by the jury in
Nichols
-v- Marsland
was thought to be wrong by the House of Lords, which approved of the decision in
Kerr
-v- The Earl of Orkney
(1857) 20 D. 298, on which Mr. Comyn relied. In the latter case Lord
Justice-Clerk Hope said:-
136. It
is stated in
Charlesworth
and Percy
at page 902 that to be an act of God an occurrence must be such that it -
137. The
third requirement was adopted by the House of Lords in
Greenock
Corporation -v- Caledonian Railway
,
and, while supported by a line of authority, that decision departed from
another line of authority represented by cases such as
Nichols
-v- Marsland
and
Nitro-Phosphate
and Odam's Manure Company -v- London and St. Catherine's Docks
(1878) 9 Ch. D. 503, to which I will refer later in another context - cases in
which it was held that to constitute an act of God it was sufficient to show
that the occurrence could not reasonably be anticipated or guarded against.
The authors of
Charlesworth
and Percy
state that, in order for the defence to succeed now, it must be proved by the
defendant that it was impossible to anticipate the occurrence or to guard
effectively against it and they point out that the defence was not established
where there had been an exceptional storm; a rainfall of extraordinary violence (
Greenock
Corporation -v- Caledonian Railway
);
an exceptionally heavy snow storm; a very high wind; or an extraordinarily high
tide. They go on to suggest that the only circumstances in which the defence
would be likely to succeed in the United Kingdom would be if some catastrophe
happened as a result of an earthquake, a volcanic eruption or a tidal wave of
vast proportions.
138. The
views expressed by the authors of
Charlesworth
and Percy
are obviously informed by the supremacy of the decision in
Greenock
Corporation -v- Caledonian Railway
over the decision in
Nichols
-v- Marsland
.
Apart from the distinguishing feature which I have already referred to, that
the finding of fact in
Nichols
-v- Marsland
was made by a jury,
Nichols
-v- Marsland
was
also distinguished in
Greenock
Corporation -v- Caledonian Railway
on the basis that, having reference merely to the storage of water as in
Rylands
-v- Fletcher,
it did not affect the question of liability for interference with the course of
a natural stream as laid down in other authorities, such as,
Kerr
-v- The Earl of Orkney
to which I have already referred (see the speech of Lord Finlay, L.C. at page
573 and the judgment of Lord Wrenbury at page 584). Another distinguishing
feature was that
Greenock
Corporation -v- Caledonian Railway
was an appeal from the Court of Session in Scotland and the issue was whether
the extraordinary rainfall which caused the stream to overflow in that case was
a damnum fatale under Scottish Law. In his speech Lord Finlay, L.C. stated at
page 571 that the authorities justified the view of the law propounded by
Professor Rankine in his work on the
Law
of Land Ownership in Scotland
in the following passage:-
139. I
have quoted this passage because it discloses that even under the law of
Scotland the strictures of the concept of damnum fatale gave way to the
existence of a state of things for a period of long prescription. Immediately
before 25th August, 1986 the dam at Paddock Pond was of sufficient antiquity to
be "fortified by prescription".
140. In
my view, the principle to be derived from the line of authorities which includes
Nichols
-v- Marsland
and
the
Nitro-Phosphate
case is more in line with the current concept of tortuous liability under the
rule in
Rylands -v- Fletcher
,
as exemplified by the decision of the House of Lords in
Cambridge
Water Company -v- Eastern Counties Leather Plc.,
than
the decision in
Greenock Corporation -v- Caledonian Railway.
Moreover, on the facts, the instant case is closer to
Nicholas
-v- Marsland
than to
Greenock
Corporation -v- Caledonian Railway
.
Accordingly, in determining whether Coillte is absolved from liability for the
consequences of the dam failure by reliance on the defence of act of God, I
consider that the test to be applied is whether the storm on the 25th August,
1986 could reasonably have been anticipated or guarded against by Coillte. I
am satisfied that the evidence shows that the storm did fall within the
category of the most extreme natural phenomena and could not reasonably have
been anticipated or guarded against, so that the defence of act of God
succeeds.
141. Accordingly,
the Plaintiff's claim against Coillte under the rule in
Rylands
-v- Fletcher
fails.
142. It
was submitted on behalf of the Council and Uniform that the acts and omissions
which were alleged to constitute a breach of duty on the part of these
defendants did not cause the flooding in the Plaintiff's premises and the
resulting damage. Similarly, it was submitted on behalf of Coillte that the
escape of water from Paddock Pond, whether occasioned by conduct on its part
which it was alleged constituted a breach of duty or by an act of God or
otherwise, did not in a legal sense cause the flooding and consequent damage in
the Plaintiff's premises. Having held that the claims in negligence against
the Council and Uniform are not sustainable and that neither the claim in
negligence nor the claim under the rule in Rylands & Fletcher against Coillte
is
sustainable, strictly speaking, it is not necessary to address the issue of
causation. However, as that issue absorbed by far the greater part of the
hearing time, I propose expressing my opinion on it.
143. At
the very end of a long trial an interesting issue arose on causation. It arose
primarily out of Mr. Keane's submission that, as regards Coillte, the crucial
question on the issue of causation is whether the dam break waters added to the
peak of the flood in the Plaintiff's premises. Mr. Keane submitted that, even
if the dam break waters had contributed at any stage to the flooding in the
Plaintiff's premises, if the natural flood subsequently increased the level of
water within the Plaintiff's premises, that is to say, if the dam break waters
passed through and were replaced by natural flood waters, then the natural
flood was the cause of the flooding. Mr. Comyn contended that this proposition
is not correct as a matter of law and he cited the decision in the
Nitro-Phosphate
case in support of his assertion. That case was concerned with the liability
of a defendant, a dock company, which, it was held had been under a duty at law
to maintain a retaining bank around its dock at a height of 4 ft. 2 inches
above Trinity high-water mark, but had allowed the retaining bank to be below
that level. In November 1875 an extraordinarily high tide took place and the
river feeding the dock rose to 4 ft. 5 inches above Trinity high-water mark, in
consequence of which the water in the dock overflowed the bank and damaged the
property of a neighbouring landowner. It was held that the extraordinarily
high tide was an act of God. At first instance a declaration was made that the
whole damage sustained by the plaintiffs was due to the defendant's wrong. On
appeal, delivering the judgment of the Court, James L.J. said at page 526:-
144. James
L.J. then went on to deal with a submission that the whole damage was not due
to the defendants' neglect and stated:-
145. As
was pointed out by Counsel for the Defendants, the
Nitro-Phosphate
case is cited in
Charlesworth
& Percy
at page 913 as authority for the proposition that a person who diverts the
course of a natural stream may be able to establish, by way of defence, that
even if the diversion had not occurred, the plaintiff's damage would have been
the same.
146. It
seems to me that the ratio decidendi of the
Nitro-Phosphate
case is that, if it could be established that there were two causes of the
damage to the plaintiff's property, the wrongdoing of the defendant and vis
major, there should be an apportionment so that the defendant should only be
liable for the damage attributable to its wrongdoing. The head-note in the
report bears out this interpretation. Interpreted thus, the decision does not
give rise to any conceptual difficulties in this post Civil Liability Act, 1961
era.
147. It
was submitted that the Plaintiff's case against these Defendants on the issue
of causation was tied entirely to the evidence of Dr. Samuel and, in
particular, to his modelling of the flood event, and this was conceded,
properly in my view, by Mr. Comyn. It follows that unless the Plaintiff has
established as a matter of probability that the modelling exercise accurately
mirrored what happened on the night of the storm and that the results of the
exercise accurately reflected reality, the Plaintiff has failed to establish
causation.
148. I
have outlined above in considerable detail the criticisms of Professor Cunnane
and Dr. Bruen of the modelling exercise and it is not necessary to reiterate
them here. Suffice it to say that I am satisfied that the criticisms are
well-founded and I am not satisfied that the results of the modelling exercise
accurately reflected the actuality of the flood event, and, therefore, the
conclusions drawn from the results do not stand up. In my view, the most
striking and significant disparity between the model simulations and what we
know of the actuality on the night is that the model did not, on any run,
achieve the maximum water level within the Plaintiff's store which was observed
by Mr. Garland and Mr. Flanagan on the night. In my view, Professor Cunnane's
conclusion that the volume of water in the model was underestimated must be
correct and, in my view, on the basis of the evidence of Mr. Doyle and Mr.
Kennedy, it was grossly underestimated.
149. Not
only does the evidence adduced by the Plaintiff fail to establish a causative
link between the breach in the river wall and the complained of construction
works, on the one hand, and the flooding of the Plaintiff's premises, on the
other hand, but the evidence adduced by these Defendants indicates a high
degree of improbability that such link existed. I am satisfied on the evidence
that the peak flow was at least 285 cumecs and that it was probably higher and
that the primary cause of the flooding was the inability of the river channel,
which had a capacity to carry a flow of 200 cumecs, to accommodate the peak
flow. Moreover, having regard to the evidence of the extent of the flooding,
both upstream and downstream of the bridge, the extent of the river wall which
was over-topped and the anecdotal evidence of the traditional source of
flooding in Little Bray, the only reasonable inference which can be drawn is
that what was happening in the vicinity of Bray Bridge was only of the minutest
significance, if any, in the flooding process.
150. Mr.
Prendiville's observations, in my view, are the most reliable record we have of
what happened on the night and I accept Professor Cunnane's analysis of those
observations as to the significance of the breach in the flooding of the Little
Bray area. In my view, it has not been demonstrated that water flowing through
the breach was a material element or a significant factor in the flooding of
the Plaintiff's premises. In relation to the afflux at the bridge, whatever
the correct measurement of the afflux, in my view, the Plaintiff has not
established that the drainage construction works, rather than natural
processes, were a material element or a substantial factor in creating it.
151. On
the causation issue, the position of Coillte is different from that of the
Council and Uniform. The water which had been impounded in Paddock Pond
escaped, it joined the Dargle and it flowed through Bray and into the Irish
Sea. In my view, the evidence establishes that the dam break waters did have a
significant effect upstream and they were certainly an important contributory
factor in the collapse of Valclusa Bridge and in Mr. Barnwell's frightening
experience.
152. However,
the issue which arises here is whether the dam break waters were a material
element and a substantial factor in the flooding of the Plaintiff's premises.
On that issue, in addition to the results of the modelling exercise, we have
the evidence of the so-called "surge" and the inferences to be drawn from that
evidence.
153. The
criticisms of Professor Cunnane and of Dr. Bruen in relation to the modelling
exercise are compounded in relation to the dam break waters because of the
controversy, which I cannot resolve, as to the volume of water which escaped
from Paddock Pond, which was a finite volume of water. There are other
conflicts on the evidence which I cannot resolve, for instance, at what rate
the dam break waters attenuated on the journey to Bray and how much of the peak
discharge at various points, for instance, River Lane or further downstream at
Bray Bridge, was attributable to the dam break waters. Dr. Samuels' estimate,
on his evidence, was that at Bray Bridge it was 13.5 cumecs in a total
discharge of 233.5 cumecs - about 6%. I appreciate that this is a crude
approach and that I have rejected Dr. Samuels' evidence on this point. However,
it is indicative and it constrains one to ask how could Coillte be held to be
wholly responsible for the flooding of the Plaintiff's premises, which is the
case that was made.
154. The
manner in which the Plaintiff's claim against Coillte is formulated is that the
results of the modelling exercise suggest that it was the presence of the dam
break waters which triggered the flooding in the Plaintiff's premises, in that
the results suggest that the natural flood alone would not have reached the
threshold level of the premises. Leaving aside the question of whether the
model accurately reflected the volume of water which was coming downstream,
there seems to me to be a fundamental flaw in approaching the question of
ascertaining responsibility for the flooding of the Plaintiff's premises in
this way in the light of the evidence. In general terms, it is clear on the
evidence that there was flooding in Little Bray before the arrival of the dam
break waters and that the flood level continued to rise for at least an hour
and probably longer after the dam break waters would have passed through Bray.
156. It
is undoubtedly the case that for an hour around midnight the presence of the
waters from Paddock Pond had some effect on the volume of water spreading out
over Little Bray and on the level of the flooding in Little Bray but, in my
view, it was manifestly not an effect of an order which would justify the
conclusion that the flooding of the plaintiff's premises is solely attributable
to the waters from Paddock Pond.
157. Moreover,
it seems to me that, had the Plaintiff made the case (which it did not) that,
on the authority of the
Nitro-Phosphate
case, there should be an apportionment between the damage done through the
fault of Coillte (assuming for the purpose of this hypothesis that Coillte was
at fault) and the damage in respect of which Coillte was blameless, it would
not be possible to do such apportionment. The decision in the
Nitro-Phosphate
case is predicated on the premise that it would be possible to identify a
substantial and ascertainable portion of the damage fairly to be attributed
solely to a factor in respect of which the defendant in that case was
blameless. In the instant case, in my view, the evidence of the eye witnesses
of the event indicates that the storm, that is to say, the natural flood, was
overwhelmingly the significant cause of the flooding in Little Bray. Taking
the evidence as a whole, in my view, it is not possible to identify a
substantial and ascertainable portion of the damage which could fairly be
attributed solely to the effect of the presence of the waters from Paddock Pond.
158. Finally,
in relation to the sudden increase in the level of the water at Lower Dargle
Road and Haughton's Junction observed by Mr. Crinnion, Mr. Sterling and Mr.
Eaves which occurred sometime between 11 p.m. and 11.30 p.m. on the 25th - the
so called "surge", in my view, to infer that this was solely attributable to
the arrival of the dam break waters would not be the appropriate inference to
draw. No doubt the presence of the dam break waters had some effect. But it
must also be assumed that the six hours of very intense rain which were just
ending also had an effect. The incessant rain must have caused an inexorable
rise in the level of the river and, on its own, may have increased it to a
point at which it overtopped the river wall opposite Haughton's Junction. I
was impressed by Mr. Kennedy's argument that, if there was a distinguishable
surge which was solely attributable to the arrival of the Paddock Pond waters,
one would have expected the flood level to settle back to a lower level after
the Paddock Pond waters had passed through Bray, which we know did not happen.
The probability is that it was a combination of both factors which caused the
"surge" observed by the eye witnesses.