Global retailer - European headquarters

In keeping with our commitment to deliver work of the highest standards, as efficiently, cost-effectively and safely as possible, we carried out a characteristically meticulous and thorough planning process for this project. This led us to identify several methodologies that could help us to enhance project productivity and effectiveness.

For instance, with the invaluable support provided by the construction engineering and digital experts of our in-house design team, we devised a value engineering option to increase the reinforcement in the perimeter pile design, in order to allow for a reduction of rebar in the liner walls.

We also were able to amalgamate the design of the temporary propping at capping beam level with the pile design works, which allowed for just one level of propping. This single layer was easier and faster to remove, once the B1-level slab was poured.

Because the site is set directly across from the Watford Junction rail station and sits on a busy intersection, with neighbouring houses and offices overlooking it – we needed to formulate a plan that would permit continued construction access, while causing only minimal impact to our neighbours.

As a result of our in-depth research and preparation process – underpinned by state-of-the-art building information modelling (BIM) data – we proposed the use of top-down construction on the gantry slab section of this project. By pouring the ground-floor gantry slab first, in advance of bulk excavation works, we were able to deploy, maintain and manage a one-way traffic system on the site. This created zero wider impact and played a critical part in limiting the project’s effects on the surrounding residents and offices.

The gantry slab also freed up valuable storage space and provided a location for the temporary site welfare units.

The early use of a tower crane on site was another means that we identified to enable us to operate more efficiently in the site’s limited area. We deployed a crane that was specially designed to be installed on four-plunge columns and a steel grillage. It was also propped back to corbels on the gantry slab. Our design allowed the tower crane to be put in place and operational prior to the commencement of bulk excavations.

Weather can often be a hinderance on construction projects – especially in the UK. However, the summer was one of the hottest and the driest summers ever documented in England. The balmy temperatures and lack of rain offered a boost to our programme, helping our works to progress extra smoothly.

In fact, we achieved record amounts of earth removal over the summer period – transporting approximately 33,000m3 of material from the site, which translates to 4,000 lorries. The use of the gantry slab, together with the dry conditions, enabled a highly successful muck shift operation.

At the peak of our muck-away operations, we were removing up to 130 loads of material a day. The use of local tipping facilities, a one-way traffic system and experienced Careys traffic marshals all led to our successes.

At Careys, we are committed to protecting and preserving the environment. On this project, we dramatically reduced the carbon footprint of the earthworks removal process by transporting the made ground element of the basement excavation to our bespoke Careys soil washing plant, rather than to area landfills.

At our wash plant, the excavated materials were processed to remove contamination and produce aggregates, which were then reused on other Carey sites across London. Rather than sending construction waste to area landfills, we were able to prepare it to be recycled and reused in our other sites across greater London.

In addition, we used natural strata materials excavated on this project to produce an environmental clean cap and working platform over contaminated ground at another nearby Careys’ site. We did this with full Environment Agency approval, under a Claire protocol. By taking this step, we were able to significantly reduce the transport impact of both removing materials from one site and importing them to another – lowering carbon emissions by up to 70%, in the process.

Also, throughout the project, the team has set up, maintained and continually reviewed various types of environmental monitoring. These have included weekly movement monitoring of surrounding roads and structures, load monitoring on the propping system, noise, dust, and vibration monitoring, as well as the use of an on-site weather station.

Additionally, on this Watford-based project, we have demonstrated our ongoing dedication to giving back to the community. The development is within a designated employment area and will form part of the local council’s plan to promote sustainable economic growth and reinvigorate Watford’s employment market by attracting and retaining high-quality office occupiers.

From a health and safety perspective, we have worked 130,000 hours on this project without a serious injury – which highlights our strong commitment to the security and wellbeing of our staff.

There were two site visits from representatives of the Considerate Constructors Scheme (CCS) – a national initiative set up by the construction industry to improve its image and encourage best practice. From the time of the first CCS visit to the second, we went from strength to strength, raising our already respectable score of 40 to 42/50. Indeed, in two categories – caring about appearance and protecting the environment – we earned the scheme’s “exceptional” rating.