Haweswater Aqueduct Resilience Programme (HARP) - Ground Investigation Case Study

Coventry I Chester I Exeter I York

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CASE STUDY Haweswater Aqueduct Resilience Programme (HARP) A large scale complex ground investigation for a major feat of engineering

The Project

Location

In 2019 Geotechnics, as an AMP7 Framework Supplier, was one of the specialist geotechnical suppliers appointed by United Utilities Water (UUW) to undertake extensive ground investigation works for UUW’s single largest project in a generation, The Haweswater Resilience Project (HARP) – a £1bn project that will take around 10 years to complete.

The existing Haweswater Aqueduct is a major feat of engineering built between 1933 and 1955. For the last 60 years it continues to serve approximately 2.5 million people in Cumbria, Lancashire and Greater Manchester with clean water. After several outages and inspections the existing aqueduct has, in sections, come to the end of its design life and a new improved structure is required to continue carrying fresh water to millions of people in the north of England for generations to come.

Stakeholder Map, Source; United Utilities' website

The proposed work is taking place across six sections of the 110km pipeline through Cumbria, Lancashire and Greater Manchester.

110 KM / 68 MILES

Original construction of the Haweswater Aqueduct

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£1BN TOTAL

10 YEAR £5M GROUND PROGRAMME INVESTIGATION

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Collaboration UUW introduced the Geotechnics Project team to a group of specialist ground engineering tunnelling consultants that had been brought in by UUW to focus specifically on the ground investigation deliverables so as to reduce ground risk for the Client and future bidders of the works. With this specific addition to the Project team came a change to the project scope with more emphasis made on high quality technical data, particularly where tunnelling was required.

UUW encourage and champion collaborative working and high levels of communication across disciplines – this was demonstrated when Geotechnics were introduced to the new members of the team. At meetings the Project Team collectively discussed the aims of the ground investigation and invited Geotechnics to contribute as to how we could achieve the change in the scope/specification.

After collaborating with UUW and its technical advisors a revised technical driven scope of works and specification was issued to Geotechnics.

Ongoing communication and variations between UUW, Geotechnics and the wider Project Team was managed via UUWs Bentley Project Wise software - this helped to streamline email communications and on occasions opened up discussions/transparency to a wider audience than email may have done.

Delivery An appreciation of the inherent challenges, combined with discussions with the wider Project Team, led to a number of key measures and solutions.

Supervision and logging of rock cores was critical, meaning additional resource with specific emphasis on more senior and technical staff was required to supervise and manage the revised works. This included siting a CGeol qualified and ROGEP registered Principal Engineering geologist on site to supervise less senior engineers and to quality check all the logging of rock cores, photography, core testing and sampling.

A rock core logging workshop was actioned by UUW specialist consultants for all logging engineers to ensure the level of detail, consistency and accuracy was maintained across all sections of the project. The following flow chart was actioned following agreement with UUW.

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Core logging flowchart

Due to the scale and technical nature of the works a more comprehensive and weather tight logging facility and office was required, somewhere both Geotechnics, UUW and their specialist consultants could work together, closer, to enable quicker and informed decisions to be made in a safe and timely manner.

Given the sensitivities of undertaking a project like this with many stakeholders involved it was agreed and actioned that Geotechnics would employ an individual to act as a Third Party Liaison Officer as the ground investigation’s public interface to ensure the smooth logistical operation of the works. It was key that all staff and suppliers were made aware of the importance of respecting the land and its tenants and that all bought in to this ethos.

With the change of the Scope and Specification and due to the environmental and seasonal setting it was soon realised that conventional plant and machinery would not be suitable for the project without causing damage to the land and creating an unacceptable H&S risk.

After several site visits it was agreed that temporary roadways in the form of aluminium trackway was required for the duration of the works. This involved many teams of wagons laying trackway in upland fields and across boggy terrain.

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Outcome Geotechnics, UUW and its specialist tunnelling consultants all learnt from the experience working on this project. As a team we all realised that each of our disciplines played a small but nevertheless an important role in a much larger jigsaw-esc project. This benefited greatly from good relationships being formed between different parties that all bought in early on to the ethos of mutual respect and cooperation.

Clear communication was fundamental to this successful project to ensure that the product Geotechnics delivered realised what was to be achieved and to the highest quality possible.

UUW’s commendation of Geotechnics’ work as part of a larger team effort recognised the technical excellence of Geotechnics’ staff and suppliers. A testament to this recognition involved UUW requesting that Geotechnics be involved in an additional section of the works that had not been tendered for previously.

Cable percussive drilling commences

To aid interpretation of rock core logging additional downhole geophysical logging was actioned in each of the boreholes.

The close working relationship between Geotechnics and UUW meant that we were able to discuss requirements and continue to deliver on the project.

On completion each borehole was flushed and left for a minimum of 24hrs before geophysical logging could commence. A series of different geophysical suites were undertaken dependent upon physical rock core logging results and proposed method of pipeline construction at the location e.g. tunnelling, shaft sinking or open cut.

To aid interpretation of the local hydrogeological setting numerous in situ permeability tests, in the form of packer tests were actioned. After a review of the downhole geophysical log UUW specified the Packer Test section depths. The packers were deployed at specified depths and inflated to isolate the test section.

An MP1 pump, rated to 90m maximum head of water, was positioned above the packer set-up and pumped to remove 3x the combined volume of the test section and riser. Prior to discharging to the IBC the pumped water was passed through a flow cell and a multiparameter which read and recorded the chemistry with samples sent for analysis.

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