| ASSET MANAGEMENT


Going deeper underground


The inspection of 50km of aqueduct tunnels hundreds of metres beneath the ground and mobilisation of several hundred specially trained engineers is not the kind of job that comes around very often − only once in 60 years in fact. Steve Turner reveals all.


HAWESWATER is one of United Utilities’ (UU) most prized assets. It was built between


1933-1955 and


commissioned in 1956 by Manchester Corporation to transport water from the Lake District for use in Manchester.


The aqueduct is 134km long and runs from Haweswater


Reservoir in


Cumbria to Heaton Park, east of Prestwich in Greater Manchester. Today, the total daily capacity of the trunk main is 570Ml of potable water, all of which is gravity fed, supplying around two million people. To the south of Haweswater Reservoir are six concrete- lined tunnels, all of which are 3m diameter and have a combined length of 50km. The tunnels are linked by four pipe siphons, each comprising two 1.2m and two 1.3m steel pipelines, together with a few short lengths of cut and cover conduit.


Preparation


United Utilities has been working towards the full inspection of the concrete pipe’s length for a decade to ensure that the network of supporting treatment works could operate effectively whilst


Haweswater was


offline for the two and a half week outage period. The findings allow United Utilities to plan future maintenance work to keep water flowing for another half a century and beyond.


Land & Marine was appointed to undertake the


Tunnels


Haweswater and


Aqueduct Conduits


Inspection, which provides the first detailed information on the condition of the concrete pipe’s entire length across the 50km network of tunnels.


With such a specific outage period leaving no room for error, critical success factors have been our ability to guarantee highly trained and skilled operatives in a concentrated time frame, underpinned by the project team’s stringent pre-planning and


in-house technical


innovations to support the above and below ground teams.


With numerous tunnel


entry points, 22 different compounds, and underground and above ground crews, the labour requirements of the contract were one of the biggest challenges Land & Marine addressed. Several hundred people worked on the project at any one time with six teams on day shifts and four teams on night shifts.


A typical inspection team was made up of three drivers, two concrete repair specialists, a supervisor, a paramedic, a structural engineer and client representatives; with additional


technical back-


up provided by specialists in GPR, alignment surveys and repair techniques.


The project team was able to draw upon the capability and expertise of parent company J Murphy & Sons and identify the right skills and people for the type of works that were to take place. Drawing from its extensive human resources, more than 150 Murphy employees were trained for the project. A training simulation camp in Kendal was established between the client, Land & Marine- Murphy and specialist sub-contractors. Each


operative undertook


a comprehensive five-day training course before being approved to carry out the inspection and surface works. The training was adapted and tailored specifically for the works and included a range of


training such as emergency rescue,


as


health and safety well


as psychological


fitness tests, health screenings and


physical tests.


This prepared operatives and ensured that they were highly competent to meet the demands of the project, in particular, working for long periods in small spaces below ground.


Innovation


Only 10km of the aqueduct tunnels were safely accessible on foot from six different location points, while the remaining 40km were very difficult to reach. Operatives were often traversing up to 10km from the retrieval point.


The quantity of equipment 8 | WET News | December 2013


required under ground for any given length of time was also a key factor. It included tools, food, toilet and welfare facilities, and repair materials. We worked with the client to develop mechanical equipment that could be utilised to ease the operation in a restricted 2.6m diameter space.


Reviewing best practice and ideas from across the world, the team deployed the


A typical


inspection team was made up of three drivers, two concrete repair specialists, a supervisor, a paramedic, a


structural engineer and client


representatives


use of Vehicle Access Systems (VAS), which are lowered into the tunnels at the most remote entry points.


The vehicles are adapted baggage-handling electric vehicles, the likes of which you see zooming around the world’s airports and runways. Taking the basic model our in-house design team and bespoke facility in Bromborough, Merseyside, was able to trial, test and reconfigure


the


and trailers to our specific requirements.


Some


vehicles 16


vehicles and trailers were specially adapted for the environment. The VAS greatly assisted the inspection


process, adapted


in such a way that they were able to be driven down the tunnels and converted into working platforms, to carry men,


specialist equipment


and welfare provisions. A key requirement of the project was that


the team


were trained in self-rescue, and we worked closely with Lancashire Fire & Rescue and Cumbria Fire & Rescue as advisers during our training process.


Another successful


innovation was the in-house modification


of electric


stretchers which were placed within the walking sections of the tunnels for use in an emergency. These were adapted to fit the diameter and profile of the tunnel so that if a team member needed to be evacuated in the event of an emergency, the manual handling of lifting a normal stretcher in a confined space was eliminated.


Inspection


The Land & Marine team gained initial access to the site on September 29 and completed the outage on October later.


16, just 17 days


During that time, the inspection involved a visual survey, EDM survey, single laser vertical measurement, video and audio recordings and Ground Penetrating Radar (GPR) of the tunnels and conduits. It also took in a tethered CCTV condition survey and a Sonar survey to determine circularity of the pipe and a hydrophone detection survey to identify any points of leakage of the single line siphons.


A logistically demanding and unique project, it required the knitting together of people from Murphy, as well as specialist sub-contractors and consultants. The benefit of these wide-ranging experience and skills, along with the input from the office teams at Land & Marine in Bromborough and Murphy in Golborne and London, were utilised to safely deliver the project in the very short time frame.


The 60-year old tunnels and conduits were found to be in a much better condition than had been anticipated, only requiring some limited repair work.


Nothing was found to compromise the quality of the water flowing through it. The Haweswater Aqueduct


was a feat of high quality, precise civil engineering when it was built all those years ago, and these findings will sustain it for another half a century and beyond. ■


Steve Turner is Land & Marine’s senior project manager.


The facts


• 500 plus people inducted over the project cycle April – October 2013


• 200 people trained in the onsite training facility for tunnel works


• 50,000 man hours worked on site • 16 shuttle vehicles • 22 access points and site camps


• 24-hour working involving 240 people in any 24-hour period


• 17 days outage period • Zero accidents


Project specs


• Conducting a detailed structural analysis of Haweswater aqueduct


• Project has taken ten years to plan


• All contractual work completed plus non- planned additional alignment surveying and non-planned completed


48 critical repairs


• Ensuring supporting treatment works can take the strain while Haweswater is offline


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