Ryan Browell, Site Manager of Brunton Park flood alleviation scheme.
Originally written for the Concrete Society Magazine, January 2017:
RYAN Browell, site manager for Seymour Civil Engineering, talks about the complexities of the Brunton Park Project, which saw the North East-based specialist tasked with sewer network improvements as well as re-routing a section of river for flood alleviation on behalf of Northumbrian Water.
“This was arguably one of the most complex projects the business has carried out, and was unique in terms of the environment we had to work in, having to negotiate around people’s homes in a high density residential area, including gardens, a river and even a golf course.
“In total, approximately 1,000 properties were directly affected by the construction works taking place over the duration of the project.
“As with any project, our aim is to get it right first time. But there was added pressure because of the environment we were operating in. We actually had to dig out people’s gardens, and at one stage had to pump water through their garages.
“Before we got to that stage, Seymour Civil Engineering had to install a 16m bridge, 4m wide, which was robust enough to withstand nearly 6,000 wagon movements. The bridge was transported in two longitudinal sections each weighing 12 tonnes. A 150 tonne crane was used for the installation.
“The project was designed to significantly reduce the risk of flooding to more than 100 properties in a housing estate on the outskirts of Newcastle Upon Tyne. It was an innovative and creative solution to a problem and, at the same time offered vital protection for the long-term.
“The project ran in two stages, from October 2014 to September 2015 and then from March 2016 to October 2016.
“To implement the sewer network improvement, we had to install 2km of Gravity Pipework, ranging from 225mm diameter plastic pipes to 900mm diameter concrete pipes. The vast majority were installed within the public highway by means of open cut.
“We used Building Information Models (BIMS) and GPS Modelling technologies throughout the project, with the 3D digital representation on board the excavator or bulldozer enhancing grading accuracy, which in turn reduced the need for profile rails and batter rails and reduced overall engineering time.
“On top of that, the process eliminates the Health & Safety risks associated with working in the close vicinity of moving plant.
“To give an idea of the size of the work, a 7.5m diameter 16m deep Storage Shaft with segmental cover slab and pump return was installed, as well as 120m of 1.8 diameter Storage Tunnel by pipejack.
“This section of the work gives a good example of Reactive Contractor Initiated Design Changes. The initial planned method was by means of underpinning a 9m diameter shaft, but at a depth of between 3 and 4m we encountered running sand which ultimately prevented us from going any further.
“Within 24 hours, there was a revised design proposal signed off which resulted in workers jacking down a 7.5m diameter shaft within the previously installed 9m diameter. While this was a positive, the negative side resulted a deeper than planned tank to retain the storage design.
“For the implementation of the flood defence works, we had to construct 450m of earth flood embankment, 300m of RC with a working area in a corridor of just 5m, and brick faced flood defence wall which was all constructed within private residential gardens.
“We used a C35 standard mix to build the flood defence wall because of its compressive strength.
“From ground level we dug down a metre, then went further to add a toe-in so the water wouldn’t seep through when we hit clay.
“Concrete formed the basis on the centre core of that wall, with brick cladding cosmetically added. In other projects a brick construction may have been suitable, but in this one concrete was vital to make it fit for purpose – a durable, credible construction that acts as a flood defence barrier.
“The project involved upsizing more than two kilometres of new surface water and foul sewers, and we had to use many methods including open cut, microtunnelling, pipejack tunnelling and caisson shaft construction with submersible sewage pumps and pipework installed with the storage shaft to return storm flows to the network.
“In addition, 400m of new channel was required to re-route the section of Ouseburn river, with an excavation of 7,000m3 of earth to create 5,500m3 of additional surface water.
“A total of 15,000 tonnes of construction material – mainly clay, concrete and aggregates required for forming the Bund, Diversion Channel and Embankment “Retaining Structures – were imported and 45,000 tonnes were exported, all of which were utilised as engineering fill to cap off a local landfill site.
“With concrete, you are working with a live product. There is no room for error at all when using concrete and tarmac. It’s like working on an egg timer as soon as the concrete leaves the plant to the site, everything has to fall into place.
“Our team hasn’t learned about concrete overnight. The practicalities of placing it successfully are varied.
“We are a great respecter of concrete. It has never let us down, but equally we have a skilled team who know how to use the product.
“People outside the sector may think ‘it’s only concrete’, but it is vital we keep abreast of developments and embrace any new technology surrounding concrete.”