Northumbrian Water Ltd v Sir Robert McAlpine Ltd

Introduction

The Claimant (“NWL”) is the statutory sewerage undertaker operating in the North-East of England appointed by the Secretary of State pursuant to his powers contained in the Water Industry Act 1991. There is a public sewer operated by NWL passing under Newgate Street, Newcastle upon Tyne.

The Defendant (“SRM”) is a well known Company in the construction industry. In January 2008 SRM was developing a construction site known as and situate at Eldon Square Phase 3, Newcastle Upon Tyne. The development site was on the east side of Newgate Street and close to premises known as 117 Newgate Street, Newcastle Upon Tyne on the west side which was occupied by the Co-Operative Group (“the Co-op”)

On 23^rd January 2008 May Gurney, the piling subcontractor of SRM, carried out piling works and in doing so poured concrete in order to create pile 215. It is not in dispute that some of the concrete that was poured escaped and that a second attempt was made later that day when approximately 25% more concrete was poured.

Unbeknown to NWL and SRM there was a private drain at a depth of approximately 3.18-3.7 metres deep in the vicinity of pile 215. The existence of this private drain was not discovered until 6^th March 2008 when Mr Roche, an employee of SRM, carried out some research in the archives of the Discovery Museum, Newcastle and came across a 1908 plan. That drawing shows that there were two private drains connecting to the Newgate Street sewer, one from the east and one from the west. The eastern drain comprised a 12” pipe and followed a horseshoe route around what was then Hare Court. It is not in dispute that pile 215 is in the vicinity of part of this drain. The western drain comprised a 9” pipe. Its route is a straight line just to the south of what was then Chamber’s Court, which, as I understand it is underneath the Co-op’s premises.

At about the end of January 2008 representatives of the Co-Operative Group contacted NWL to advise that sewage was backing up into its premises. NWL’s investigations revealed that concrete had entered its public sewer in Newgate Street. Subsequently NWL carried out works to the public sewer to remove the concrete. The works were completed in May 2009 at a cost of £318,032.

In these proceedings NWL seeks to recover the £318,032 from SRM. It asserts that that the concrete which was later discovered to have been deposited in the Newgate Street sewer had entered from SRM’s site having been poured into the voids on the site on 23^rd January 2008 by its subcontractor May Gurney. It relies on nuisance and negligence.

SRM denies liability. It does not accept that the concrete discovered in the Newgate Street sewer was the same concrete as was poured on 23^rd and 24^th January 2008. Even if it was the same concrete the allegations of negligence and nuisance are denied. SRM submits that prior to commencing the development it carried out extensive research (including the diversion of a sewer) so as to discover and avoid damaging any of the public services in the vicinity. The existence of the private drain was unknown to both NWL and SRM and could not have been discovered by reasonable diligence. Even if it had been discovered it is by no means clear that it would have made any difference. The site was originally developed in the 1970’s and SRM assumed and was entitled to assume that any connections below a depth of 2 m would have been removed during the course of that development. It is further alleged that NWL failed to mitigate its loss. It is suggested that NWL should have acted more quickly. If it had done so the concrete could have been removed before it had cured. In the Defence SRM alleged NWL was itself negligent in failing to provide any information to SRM which could or should have put SRM on notice that there was a possibility of concrete entering the Newgate Street sewer. However this allegation was not pursued in Mr Mitchell’s closing submissions and I need not refer to it further.

These proceedings were issued on 10 February 2011. The pleadings were complete by 25 July 2011. The matter was transferred to the TCC on 25 January 2012 and detailed directions were given including the provision for single joint experts in materials testing and in respect of quantum. The order envisaged that the report from the material expert be available by May 2012. There were delays in obtaining this report. On 3 August 2012 HH Judge Walton revised the timetable and made provision for the trial to take place on 12 December 2012. As a result of further delays in obtaining the report on 26 October 2012 HH Judge Langan QC vacated the trial and relisted it for the first available date after May 2013. The report did not become available until 16 April 2013. On 17 April 2013 I refused an adjournment but agreed to remove the issue of quantum from the matters to be determined at the trial. SRM was late in filing its witness statements. In the result there were two applications before Judge Walton in the week before the trial. The first was an application by SRM for an adjournment. The second was an application to debar SRM from defending the claim. Each was refused. On the first morning of the trial SRM applied to amend its defence by adding three further allegations of failure to mitigate. For reasons I then gave and do not now repeat the applications were refused. In my view to have allowed them would have given rise to an adjournment. I also disallowed one of the witness statements on behalf of SRM on the ground that it was a thinly disguised attempt to adduce additional expert evidence at the last moment without permission.

Thus the trial duly commenced on 17 June 2013. Seven witnesses of fact were called on behalf of NWL – Beatrice Brindley, Aden Young, Keith Moreland, Mark Johnson, Stanley Richardson, David Ewles and Christopher Abbott. Three witnesses were called on behalf of SRM – Gary Hills, Neil Roche and Roger Wilkins.

The single joint expert, Dr Rachel Hardie produced a helpful report dated 16^th April 2013 in which she expressed a view (based on assumptions which are recorded in the report). She revised that view in the light of Mr Abbott’s witness statement in replies to questions from NWL’s advisors. She attended and was cross-examined by both parties.

The facts

The Eldon Square Project related to the redevelopment of Eldon Square Shopping Centre. The redevelopment work started in 2005 and was completed in 2010. The total cost of the development was in the region of £170 million.

The project was phased consisting of enabling works and three phases. Scheme 1 involved the construction of a new bus station, the removal of an old bus station, the construction of pedestrian links and 22,000 sq ft of new retail space. Scheme 2 involved the redevelopment of retail units on the east side of Blackett Bridge fronting old Eldon Square, creating 14 new shopping units comprising 48,000 sq ft of retail space. Scheme 3 was the largest phase of the redevelopment works, creating 410,000 sq ft of retail space. The works involved the demolition and redevelopment of the southern end of the centre to create a substantial new retail area.

The preparation, planning and site investigation involved on the project was extensive. This included discussions with the utility companies and a ground survey.

Before the Scheme 3 works commenced existing structures had to be demolished. It was necessary to identify all the existing services within the site. In order to identify services it was, on occasions necessary to undertake CAT scans, and to use slit trenches and trial pits. As part of the work it was necessary to divert part of the Newgate Street sewer. There were direct discussions between NWL and Cundalls (members of the preconstruction design team). None of the investigations or discussions with NWL revealed the existence of the connections shown on the 1908 plan.

On the other hand all of NWL’s plans contain a warning on them which points out that private connections are not shown but their presence should be anticipated.

The May Gurney pile record sheets show that 11 piles were drilled and poured on 23 January 2008. In each case the pile diameter was 750 mm and the drilling was to a depth of 17.8m. Pile 215 was the 8^th pile to be drilled. It was drilled twice. On the first occasion it was drilled to a depth of 17.8 m and 8.84 cu.m of concrete was poured. On the second occasion it was drilled to a depth of 4.5m and a further 2.32 cu m was poured. Pile 215 was the only pile to be redrilled. In respect of the other 10 piles between 8.65 and 9.94 cu m of concrete were poured. There is a strong inference that pile 215 was redrilled because approximately 2.3 cu m had not been retained within the drilled area and had seeped away. This inference was corroborated by the evidence of Aden Young a jet cut operator employed by Kilbride Industrial Services who were employed to remove the concrete. In paragraph 3 of his witness statement he recalls a conversation where employees of SRM mentioned that they had lost a few cu.m of concrete. They just kept pouring in concrete until the concrete stopped sinking and the hole was full.

All of the concrete was supplied from the Gateshead depot of Tarmac Limited. The dockets show that the concrete has a minimum cement content of 340kg per metre. It conformed to BS 8500 – 2 and the customer specification.

At the end of January 2008 Mr Richardson, the Regional Facilities Manager employed by the Co-op was informed that sewage was backing up at the food store at 117 Newgate Street. This was the first time there had been such a major blockage.

By 4 February 2008 NWL had been informed of the blockage and attended with a jetting crew. It was unable to clear the blockage.

On 6 February 2008 Mr Moreland, the Clerk of the Works employed by NWL attended site with a High Pressure Vactor Unit. This unit can vacuum solids such as fats and greases that frequently block units.

As can be seen from the plans the site of the blockage was between manholes 5304 and 5201 on the Newgate Street sewer. A member of the crew entered the sewer at manhole 5304 and reported debris in the sewer. As a result Mr Moreland decided that the sewer should be cleaned. At that time Mr Moreland did not believe that the Co-op private drain connected with the Newgate Street sewer.

On 7 February 2008 Mr Moreland attended at manhole 5304 where he entered the sewer. He saw sewage running into 5304 and that the blockage remained in the Co-op drain. He concluded that there was no blockage between manholes 5304 and 5201. He arranged for the Co-op drain to be vactored out. He then arranged for a probe to be inserted into the drain. The probe found an obstruction. In his witness statement Mr Moreland said that the position of the obstruction was some 20 m east towards SRM’s building site. In cross-examination he acknowledged that he could not now remember if the blockage was in fact 20m. He informed the Co-op that the problem appeared to be in the Co-op’s private drain and it was not NWL’s responsibility to remove it.

In addition to complaining to NWL the Co-op also complained to SRM about the blockage. In the result on a date which is not specified (but which was before the Co-op’s CCTV survey referred to below) Mr Roche, the experienced Works Supervisor employed by SRM on the Phase 3 development, dug a trench on SRM’s site to the east of the pile fronting Newgate Street to see if a side connection could be located near the pile. The trench was 5 metres long and 3.2 metres deep. No evidence of services was found.

On 21 February 2008 the Co-op undertook a CCTV survey of its drain. The survey revealed an obstruction in its drain – possibly concrete – at approximately 12.78m.

On 4 March 2008 Mr Moreland again attended at manhole 5304. He entered the sewer and walked towards manhole 5201. After about 20m he saw concrete set at the bottom of the sewer. He estimated that between 4 and 5 cu.m had set in the invert of the sewer.

It is tolerably plain that at this time NWL were unaware that the Co-op drain connected to the Newgate Street sewer. On 27 February 2008 Mrs Brindley, a Project Manager employed by NWL sent an e-mail to the Co-op in which she said that she did not know where the Co-op’s drain went. She also sent an e-mail to Mr Hills, SRM’s Construction Manager at the Eldon Square site in which she sent him details of NWL’s records of the surveys of the Newgate Street sewer. The location of the two private drains is not shown on any of the surveys. Furthermore in discussions between Mr Roche and Mr Moreland Mr Moreland stated on a number of occasions that the Co-op’s private drain did not connect with the Newgate Street sewer.

In the light of Mr Moreland’s comments and the lack of an identifiable source for the blockage and the Co-op’s continuing problems Mr Roche decided to carry out some research to attempt to resolve the position. By making a number of phone calls he discovered that there were some Victorian/Edwardian drainage archives held at the Newcastle Discovery Museum. On 6 March 2008 on his second visit to the Museum after about 5 hours of research Mr Roche discovered the 1908 plan. He was not allowed to take it away but he made a sketch of it which has formed part of the evidence in the case.

On 14 March 2008 Mrs Brindley attended a meeting with, amongst others, Mr Hills. By this time Mr Hills had seen the copy of the 1908 plan made by Mr Roche. Mrs Brindley had been informed of its existence by email but it is not clear whether she had in fact seen it. In any event Mr Hills confirmed to Mrs Brindley that SRM had been pouring concrete on 23 and 24 January 2008.

On 26 March 2008 a further CCTV survey of the Newgate Street sewer was undertaken by Kilbride a contractor employed by NWL. The camera was inserted at manhole 5304 and headed in the direction of manhole 5201. Approximately 15.4 m along it found apparent concrete entering from the left hand (eastern) side of the site.

On 21 April 2008 jetting of the Newgate Street sewer commenced. The work was carried out intermittently and was not completed until May 2009. Following its removal the concrete was stored in rubble sacks and weighed. The weight of the concrete removed was 1,580 kg.

On 16 January 2009 Mr Moreland was informed that the removal of concrete had revealed a connection on the eastern side of the sewer. Accordingly he attended the site in order to investigate. The sewer was entered by Mr Oxley an employee of Kilbride at manhole 5201 who progressed up sewer. Mr Oxley took a number of photographs which revealed that a circular pipe on the eastern side of the sewer. Immediately above the pipe was concrete still to be removed. There was concrete inside the pipe. This led Mr Moreland to conclude that the concrete that had come out of the pipe had set in the pipe so as to cover the pipe.

Other photographs show a connection pipe on the western side (the Co-op drain) from which concrete has been cut out.

On 9 June 2009 a further CCTV survey of the Newgate Street sewer was undertaken. The survey commenced at manhole 5304 and terminated at manhole 5201. The survey identified the eastern pipe 18.9m downstream from manhole 5304. It was a 300 mm pipe completely blocked with concrete.

The single joint expert, Dr Rachel Hardie has 25 years experience as a professional petrographer and as a geologist. In the last 17 years she has specialised as a materials petrographer, specifically in concrete, rock and related building materials. She has operated as an independent consultant for the last 13 years and has provided expert petrographic opinion in report format on all mineral based building materials for over 1,000 projects.

Dr Hardie was asked to consider two questions:

In order to see whether the concrete removed from the Newgate Street sewer was the same as that poured on 23^rd January 2008 Dr Hardie was supplied with three samples from the concrete removed from the sewer. It was not possible to provide her with samples from pile 215. She was, however, provided with three concrete cores which were obtained from the Contiguous Pile Retaining Wall within the Sprinkler Tank, in Zone 3, located more centrally within the development. These cores had been poured in March 2008, that is to say more than one month after pile 215 had been poured.

The samples were examined macroscopically and sawn to produce slices for the preparation of thin sections in order for these to be examined using a petrological microscope. The concrete slices were impregnated with blue dyed resin and mounted onto a glass slide. The mounted concrete was then ground and finally polished to a thickness of 25μm and covered with a glass cover slip. The thin sections were examined microscopically using a petrological polarising microscope.

The examination led to a number of observations:

In order to reach conclusions Dr Hardie made a number of assumptions which were set out clearly in her report:

On the basis of these assumptions Dr Hardie concluded that the concrete removed from the sewer was not the same as detailed in the Tarmac mix design for the main piling, nor the same as the concrete cores removed from the contiguous piled wall. There were similarities between the two sets of concrete samples examined in that both contain marine sand and both contain GGBS cement replacement. However the significant difference was in the presence of dolerite as a major coarse aggregate type within the concrete from the sewer. Dolerite was not identified in the coarse aggregate fraction of the concrete taken from the contiguous piled wall and was not referred to in the concrete mix design for the main piling operation.

In section 6.1 of her report Dr Hardie expressed her conclusions thus:

“It is assumed that the mix design provided has been adhered to throughout the Site Piling works from January to March 2008. It is also assumed that the cored samples received from the contiguous piled wall cast in March 2008 used the same raw materials as concrete poured at ‘the Site’ in January 2008. If these assumptions are correct, it is not likely that the concrete that entered the Claimant’s sewer was the same concrete poured by the Defendant on or about the 23/24 January 2008.”

In relation to the second issue Dr Hardie relied on published material. She inferred that curing conditions in the sewer would have been favourable and that curing would have been within normal limits. The published material suggests a period of 3 to 7 days for curing under “normal” conditions. This time period would be considered sufficient for the concrete to gain adequate strength and to resist disruption due to the conditions prevailing within in the sewer, i.e. erosion due to water flow and potential chemical attack. Reference to the graphs exhibited in the report indicates that concrete achieves two thirds of its hardness within 7 days achieving hardness within a further 14 to 21 days.

Mr Abbott is the Technical Systems Manager at Tarmac Lafarge the supplier of all the concrete supplied to May Gurney at the Eldon Square site. Before he made his statement he was informed of Dr Hardie’s comments in relation to the dolerite. In his statement he makes a number of points:

Much of the cross-examination of Mr Abbott was designed to exclude the possibility of even trace quantities of PFA in the concrete. Thus he agreed that all the concrete came from the Gateshead plant, that the Gateshead plant did not have a silo containing PFA, that none of the other tarmac manufacturing plants in the North of England had a silo containing PFA, that the wagons that were used were plant specific and they were regularly cleaned. He suggested that the tankers carrying GGBS could carry PFA but agreed that this was a remote possibility. He also suggested as a possibility that the initial priming of the delivery pipes might have contained the PFA. [This theory can in fact be discounted. First there was evidence that May Gurney used a gel for the initial priming. Second the delivery to pile 215 was one of the later deliveries on 23 January and thus the initial priming material would have been flushed through.]

In answers to questions posed in the light of Mr Abbott’s evidence Dr Hardie modified her conclusions. Her new conclusions included:

When she gave evidence Dr Hardie confirmed that Mr Abbott’s oral evidence had not changed her opinion. She repeated her view that that the samples from the sewer and the samples from the concrete piles were different visually and contained different components. However she maintained that the inferences that could be drawn from those facts had changed. In other words it was no longer possible to say that it was not likely that the concrete poured on 23 January 2013 was the same concrete as was found in the Newgate Street sewer.

She was pressed on the existence of the PFA in the sewer concrete. She agreed that its presence added to the weight of the factors indicating that the concrete was not the same. However she pointed out that only a trace (less than 1%) of PFA was found. She agreed it was a mystery how the PFA got into the concrete. She pointed out that particles of PFA are particularly fine – smaller that the sharp end of a pin head. They can be blown in the wind. Thus the existence of the PFA did not affect her modified conclusion as set out above.

The source of the concrete in the Newgate Street sewer.

In his very full and clear closing submissions Mr Mitchell submits that NWL have not established that the concrete in the sewer came from that poured by May Gurney. In so doing he points to 11 differences between the samples of concrete pile and sewer concrete tested by Dr Hardie. He suggests that NWL’s case relies on coincidence and submits that it is not sufficient for Dr Hardie to suggest that it is “possible” rather than “probable” that aggregate from different parts of the quarry are different. He points to other steps which he asserts might have been taken to establish that the samples were the same concrete.

I cannot accept these submissions. First, as Mr Singer pointed out, I am only concerned with the balance of probabilities. NWL has only to prove that it is more likely than not that the concrete in the Newgate Street sewer was the same concrete as that poured by May Gurney. Second the circumstantial evidence strongly supports NWL’s case. The circumstantial evidence includes the following features:

Third I do not agree with Mr Mitchell’s analysis of Dr Hardie’s evidence. Dr Hardie’s first report was based on the assumption (clearly stated in the report) that all of the aggregate supplied by Tarmac complied with the specification and was identical. On that basis it was possible to infer that the differences found between the two samples led to the conclusion that it was unlikely that the concrete in the Newgate Street sewer came from Tarmac. That assumption was completely destroyed by Mr Abbott’s evidence relating to the geology of the Barrasford quarry (evidence confirmed by Dr Hardie) and to the practice in relation to the certificates. It has to be remembered that the sample from the concrete piles was poured in a different place more than a month after 23 January 2008.

In those circumstances I have no hesitation in agreeing with Dr Hardie that it is not possible to infer that the differences in the samples makes it unlikely that that the concrete in the Newgate Street sewer came from Tarmac. In the result I agree with Mr Singer that the expert evidence is equivocal and does not destroy the inferences to be drawn from the circumstantial evidence.

Fourth there was the evidence from Mr Roche that he was not aware of any other concrete being poured in the area at the time. This evidence had limited support from Mr Ewles the head of building control at Newcastle City Council at the relevant time.

In all the circumstances I find as a fact that the concrete that was found in the Newgate Street sewer was the same concrete as that poured by May Gurney on 23 January 2008.

The claim in negligence

Mr Mitchell submits that the claim in negligence must fail. He submits that all proper care was taken prior to works commencing and during the works His detailed submissions are set out in 14 closely argued paragraphs in his closing submissions. In summary he submits:

In answer to these submissions Mr Singer submitted that SRM was negligent in that it had not taken sufficient precautions to see what was in the area. He made three specific criticisms of SRM. First SRM failed to discover the 1908 plan until March 2008. Second it restricted its researches to a depth of 2 metres. Third it failed to commission a CCTV survey of the whole of the Newgate Street sewer. In support of the third submission he referred me to paragraphs 8 to 10 of the witness statement of Mrs Brindley. In those paragraphs Mrs Brindley refers to meetings held with SRM’s agent on 26 September 2003 and 15 October 2003. Those meetings were held to go through the list of sewers impacted by the development and narrow down the list for CCTV surveys. It, however, appears that the decision not to commission such a survey was agreed by Mrs Brindley on behalf of NWL.

I agree with Mr Mitchell that Mr Singer’s submissions have to be considered in the light of the pleaded allegations of negligence. I also accept that none of the allegations now relied on by NWL are specifically pleaded in either the Particulars of Claim or the Replies to the Part 18 Request. There are generalised allegations in the Particulars of Claim that SRM failed to execute the works without proper regard to the presence of the sewer and a generalised allegation in the Replies to the Part 18 Request that SRM failed to investigate utility services within the vicinity of the whole works. There is a further reference to the warning that private connections should be anticipated.

However I also agree with Mr Mitchell that the obligation on SRM is not an absolute obligation. The obligation is to take reasonable care to investigate the utility services in the area, and in the execution of the works.

As Mr Mitchell points out no evidence has been led which criticises the investigation in fact carried out by SRM or its agents or which criticises the piling operation carried out by May Gurney. There is no expert evidence as to the level of investigation that might be expected in a development of this size or which criticises the piling operation. It is certainly not obvious to me that SRM ought to have searched the Discovery Museum or to have carried any further research beyond that which was in fact carried out.

In those circumstances I agree with Mr Mitchell that NWL has failed to establish that the investigation and the piling operation were not carried out with reasonable care. The allegations of negligence accordingly fail.

I should perhaps add that Mr Mitchell also submitted that the deposit of concrete on the invert of the Newgate Street sewer did not constitute damage to the sewer. All it needed was cleaning. I do not accept that submission. In my view the deposit of concrete which adhered to the invert of the sewer and cost over £300,000 plainly constituted damage. It may be that the sewer still flowed and was not blocked. However the presence of the concrete within the sewer plainly reduced its efficiency. Furthermore I do not accept that the steps taken to remove the concrete can properly be described as “cleaning”.

The claim in nuisance

Both Counsel appreciated that the claim in nuisance represented the central battleground between the parties. There was a fundamental difference between Counsel as to the relevant law.

Mr Mitchell referred me to two recent cases at the highest level where there has been extensive discussion of the rule in Rylands v Fletcher - Cambridge Water Co v Eastern Counties Leather plc [1994] 2 AC 264 and Transco plc v Stockport MBC [2003] UKHL 61.

Mr Mitchell submitted that the claim in nuisance was bound to fail for a number of reasons:

For reasons already given I do not accept the third reason given by Mr Mitchell. Mr Singer made the following submissions in respect of the other two arguments:

Although primarily concerned with the rule in Rylands v Fletcher both Cambridge Water and Transco contain discussions on the relationship between the cause of action in nuisance and the rule in Rylands v Fletcher. Whilst this is not an appropriate place for an extensive academic discussion of the speeches in those cases the following points emerge.

In paragraphs 9 and 10 of his speech Lord Bingham made it clear that the rule in Rylands v Fletcher is a sub-species of the law of nuisance. There must be an escape from one tenement to another. It does not include a claim for death and personal injury since such a claim does not relate to any right in or enjoyment of land. In order to succeed under the rule in Rylands v Fletcher it has to be established that the thing the Defendant has brought on to his land is something which “... will naturally do mischief if it escape out of his land', 'something dangerous ...'. The practical difficulty in many cases is to determine whether the thing brought on to the land satisfies that test. He concluded paragraph 10 in the following way:

In paragraph 27 of his judgment Lord Hoffmann explained the novelty of the rule in Rylands v Fletcher in this way:

In paragraph 33 he explained the decision in Cambridge Water in the following way:

In my view these citations support Mr Mitchell’s submissions as to the extent of strict liability for an isolated escape. They establish that the rule in Rylands v Fletcher is a sub species of the law of nuisance. They establish that in order to establish strict liability under that rule the Claimant must establish what Lord Bingham described as the “mischief or danger” test. As he said in the citation from paragraph 10 this is a test which is not easily satisfied. If Mr Singer’s submissions are correct it would mean that liability for nuisance would be established for an isolated escape where the test was not established. It would render the rule in Rylands v Fletcher unnecessary.

In this case Mr Singer does not rely on the rule in Rylands v Fletcher, presumably because he does not consider that NWL can satisfy the “mischief or danger” test. As this is a case of an isolated escape it follows that the claim in nuisance fails.

That conclusion makes it strictly unnecessary to consider whether the damage to the Newgate Street sewer was the reasonably foreseeable consequence of the escape of the concrete. However, as the matter was argued and as my view on the extent of liability in nuisance may be the subject of an appeal I shall express my view briefly.

I agree with Mr Singer that whether the damage is reasonably foreseeable is fact sensitive. I also accept that the facts of this case are different from Cambridge Water so that the decision in that case provides no clear guidance in this case. However I also agree with Mr Mitchell that the relevant question is not whether the damage is foreseeable but whether it is reasonably foreseeable. It follows that the views of Mr Roche and Mr Gill that damage to the sewer was a possibility is of limited value in resolving the issue.

The only way the sewer could be damaged was through a connection such as a drain connecting the sewer to an area close to where the concrete was being poured. In this case, as Mr Roche discovered on 6 March 2008, there was such a drain. Thus in my view the relevant question is whether the existence of the drain was reasonably foreseeable. I have already held that it has not been established that SRM was negligent in failing to detect the drain prior to pouring the concrete on 23 January 2008. For the same reason it has not been established that the existence of the drain was reasonably foreseeable. It follows that I accept the submission of Mr Mitchell that damage to the sewer was not reasonably foreseeable.

Mitigation

In the light of the above conclusions it is not strictly necessary for me to express any view on the question of mitigation. However as I have formed a clear view that there was no failure to mitigate it is right that I should express it.

The evidence of Dr Hardie establishes a very short time frame for the curing of the concrete. Concrete has achieved two thirds of its hardness within three to seven days. It had blocked the Co-op’s drain by then. It will achieve full hardness within 21 days. For the allegation to succeed SRM would have to establish that NWL should have removed the concrete in the Newgate Street sewer by the middle of February 2008. In fact NWL did not discover the existence of the concrete in the sewer until 4 March 2008. Furthermore, as has been pointed out, it did not believe that the Co-op connected to the Newgate Street sewer.

The duty on an innocent party to mitigate its loss is not an onerous one. Furthermore the burden is on SRM to show precisely what steps the innocent party should have taken and that those steps would have reduced the loss the innocent party would have suffered.

To my mind SRM has failed on both of these issues. I am not satisfied that it was reasonable for NWL to have discovered the existence of the concrete before the middle of February 2008. I am equally not satisfied that the removal would have been any less expensive to remove the concrete if it had been discovered earlier.

Conclusion

In the result I conclude:

In the result the action fails and will be dismissed.