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Mon August 08 2022

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Engineer not negligent for relying upon specialist subcontractor’s advice

22 Oct 10 CWS, and Cliveden Estates Ltd. entered into a development agreement for the construction of a supermarket in Sandwich. Cliveden engaged a number of consultants including the defendant, John Allen Associates (JAA), a firm of consulting and structural engineers with whom they had worked previously.

A formal deed of appointment between JAA and Cliveden was concluded in 1996, and, in addition, JAA provided a direct warranty to CWS.

Cliveden entered into a JCT 1980 with Quantities building contract with John Mowlem & Company Plc. The contract contained a Provisional Sum of £45,000 for vibro compacting ground improvement and also a Performance Specification for soil stabilisation by Vibro Replacement Techniques prepared by JAA. Mowlem also provided a direct warranty dated 23 December 1996 to CWS. Mowlem entered into a subcontract with Pennine Vibropiling Ltd. for the vibro compaction work, which included the full design of the ground improvement scheme. Initially Mowlem was brought into these proceedings by JAA as Third Party and, in turn, Mowlem brought Fourth Party proceedings against Pennine. On the second day of the trial a Tomlin Order was agreed between JAA, Mowlem and Pennine and Mowlem and Pennine then took no further part in the proceedings.

The site had a layer of soft and very soft clay which was treated by vibro replacement stone columns to stabilise or improve the ground, with the concrete floor slab then being cast on the improved ground. The main building structure and outside walls were supported by piles with pile caps and ground beams. The ground floor settled by as much as 110m and because it was supported in places on the pile caps which had not settled, there was significant differential settlement. This resulted in sloping floors which required remedial work to re-establish a level floor and avoid problems, such as rolling shopping trolleys, which affected the use of the supermarket.

Cliveden engaged LBH Wembley, a firm of geotechnical and environmental consultants to produce a desk study report on the ground conditions. They stated that they expected the ground to find extensive beach sand on the site, and recommended that piling should be considered. A copy of the report was provided to JAA. The director responsible for the project, Mr. Kevin Leach, wrote to Cliveden’s architect enclosing a copy of the site survey marked up with the proposed locations for boreholes. Wembley then carried out a site investigation, and found that, instead of sand, the site was underlain by clay and silts, and because of this recommended that a suspended floor be used. JAA was sent a copy of the report and asked to comment on the engineering implications.

Cracks appeared in the floor became apparent in summer 1997. JAA blamed the failure of the floor on Mowlem, arguing that the design responsibility was theirs. JAA alleged that they had asked Mowlem to accept all the responsibility for the piling at a site meeting and they had agreed.

The central issue in the case was whether vibro replacement “could never have worked on the site which was highly compressible and therefore was inevitably going to fail and the resulting building was bound to suffer from extensive and unacceptable differential settlement”. If the court were to find that vibro replacement could have worked and was not inevitably going to fail then it followed that, on this central issue, CWS’ case would fail.

If however, CWS were correct in their contention, then JAA sought to defend their position on the basis that they recommended it on the basis of advice from Keller, the geotechnical contractor, and that the way in which matters proceeded with the design being carried out by specialist sub-contractors did not call into question the recommendation. They submitted that they reasonably relied on Keller and the design carried out by the subcontractor, and that in doing so they discharged their duty of care to CWS.

CWS argued that JAA could not defend on this basis because it could not delegate their design liability by relying on the advice of Keller and the design carried out by a subcontractor. CWS maintained that JAA had not discharged its obligations by asking Keller for their opinion and receiving it and accepting it.

CWS maintained that on the basis of previous authority ann engineer’s duty is not generally delegable, and where the aspect of design is obviously outside the expertise of any Engineer or of the consultants available in the construction industry, then the duty may be limited to the exercise of reasonable skill and care in the selection of the product or specialist services. A factor in deciding whether a duty has been delegated will be whether the client has an available remedy against the specialist, for example through a direct warrant.

CWS submitted that there was no evidence that JAA had told them that, as a firm, it was not capable of providing the basic engineering services which it had warranted it could. If CWS had been aware of this, it would have commissioned another firm to do the work and give a warranty.

The judge was satisfied that a properly designed and properly implemented vibro replacement system would have been able to limit the long-term settlement levels. Together with proper design detailing, an acceptable level of serviceability would have been achieved. The system could have brought down settlements from Wembley’s figure of 80mm to 50 or 30mm, or from the experts’ figure of 95mm to 165mm, to some 35 to 60mm in the main supermarket store. With these levels of settlement the judge did not consider that serviceability problems would have been caused. Consequently, CWS’ case in relation to the central issue failed because the use of vibro replacement at Sandwich was not bound to fail.

JAA pleaded that vibro replacement was a specialist area and that a competent structural engineer would have sought the advice of specialists such as Keller who were well respected in that field, and that they did not need to seek advice from professionals, or research or trade associations. Further, this was not a case where, either they should have engaged independent professional advice, or should have advised Cliveden to do so, and that any protection which was necessary would be provided through the mechanism of the main contract and the use of a specialist subcontractor.

The judge accepted that JAA was broadly correct in this. Competent structural engineers often sought advice from specialist ground or piling contractors. Keller was certainly respected in this field and JAA had used them over a number of years. From articles and publications published by Keller, it was obvious that they had a great deal of experience in vibro replacement techniques. Given this, it was reasonable for JAA not to have sought professional advice or urged Cliveden to do so. JAA had acted reasonably in relying on Keller’s advice. Even if Keller’s advice had been negligent, JAA would not have failed to discharge their duty of care to Cliveden under their Appointment or to CWS under the warranty. JAA had not been under a duty to undertake an independent evaluation of the feasibility and risks of vibro replacement, nor to recommend that geotechnical advice should be sought from a consultant other than a specialist subcontractor.

Cooperative Group Ltd. v John Allen Associates Ltd. [2010] EWHC 2300 (TCC) 

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