Visit to the Cadent Gas HS2 site (Harvil Road, Harefield)

1      Background

As the Cadent Gas site at Harvil road is one of the first major HS2 construction sites in the Hillingdon area, a group of local residents went to visit the site to see how it operates. The site is run by Murphy, as a subcontractor to Cadent Gas. The visit took some time to be arranged by HS2Ltd but now we have been we have been invited to visit further sites at regular intervals.

The purpose of the works is to divert 2 gas mains (a main 48 inch one and a smaller one) away from the HS2 route.

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2      Impressions

We were shown around the site by the very efficient and capable manager, along with two representatives of Cadent Gas (one in a communications role) as well as the local HS2 community manager. The Cadent Gas and HS2 communications staff both noted down every question we asked throughout the visit and were helpful throughout.

The sites are very big overall, taking up a considerable amount of what was open countryside.  However they are small compared to the expected main construction sites. There has been a big investment in the infrastructure with large concrete areas and a number of semi-permanent buildings. The site office facilities include a large, very well equipped conference room (the ground floor of the two-story cabins at the front of the site). There is a large demonstration area with samples of the pipes in cross-section. There are large concrete storage tanks for waste water that collects in the shafts. This is stored for 2 weeks and tested throughout before being discharged. They are looking for a suitable discharge point in the locality, which may involve transporting the waste water by lorry to Affinity Water site on Moorhall Road.

They discussed the imminent creation of their next site on the other side of Harvil Rd. They envisage it in July, potentially involving a temporary lane closure. They were unaware of the Breakspear Rd South closure already planned for July. They and HS2Ltd agreed to check this out.

Safety is a top priority there, with limited to access to different areas for specific people only, and safety “Banksmen” monitoring each active working area.

They are trying to use the very most modern construction techniques – see examples below.  They base their practices on what TFL is specifying for inner London construction in 2 years’ time, and then expect to exceed it.  This is beyond what the HS2 Code of Construction Practice demands. The site manager described it as her dream site, where she has had the luxury of being able to set it up from scratch to her specifications and push the boundaries of what can be done on site management.

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Examples of environmentally friendly practices (in as much as a major construction site can ever be considered to be environmentally friendly) included:

  • Portable lighting systems that run on hydrogen not diesel generators. These use fuel cells to generate electricity and produce no exhaust emissions apart from clean water, and are silent
  • The use of the latest Shell GTL (Gas to Liquid) fuel to run main site generators rather than normal diesel. This is readily biodegradable and non-toxic, and significantly reduces pollution emissions
  • Damping down internal roads during dry weather every few hours to try and minimise dust
  • Recycling the Bentonite filler they use to temporarily support the holes they are making.

3      Issues

3.1     Private transport


There were around 40 – 50 private vehicles on site, with no evidence that they use public or group transport to get people on and off site. Their car park can take 100 vehicles. This gives a lie to the HS2 statement in Parliament that private “workers’” vehicles would be small in number and the workers would be expected to use public transport. It raises the question of why further separate car parking sites need to be created at HS2’s nearby sites.

3.2     Site standard

A key point about this site is that Murphy see it as their “gold standard” demonstration site, and are openly admitting they hope to get more HS2 work from it.  They did tender for some of the main contracts but did not win anything. As a result, their implementation is far in excess of the quality levels specified by HS2Ltd, with presumably extra costs to implement this level. The site manager indicated this extra investment was at Murphy’s expense and by choice, deliverable within the contract price. They emphasised that much of the equipment on the site is brand new. One of the Cadent Gas staff mentioned that the vehicles used to transport us between compounds were brand new Range Rovers hired by the week for the purpose.

3.3 Security practices

Entry to the site was tightly controlled and documented at every stage including a further controlled access to the tunnel shaft area. It wasn’t clear how much of this was genuine routine practice as, eg we had been asked to bring ID but were never asked for it. On entry to the second compound, the driver of our car was asked to show his badge but he did not have it – admission was given anyway.

3.4 Environmental protection

 Piles of topsoil and subsoil were stacked and clearly labelled, They are actively managing the stacks to ensure the topsoil is preserved – sprayed with grass seed and kept watered, and they are prepared to turn the topsoil stacks if they are to stay in place for too long.

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They mentioned recycling waste chalk filtered from the bentonite. This is being taken to Summerleaze in Denham. We realised that this means HS2-generated material is still going in to the site that will then need to be excavated for HOAC. We need to take this up with Hillingdon.

4  Conclusions

It was difficult not to be impressed by the professionalism of how the site is run and maintained.. Obviously nobody wants the sites to be there at all, but given what we are faced with, it was at least reassuring to see seemingly best practices put into place. The site is well and efficiently run with knowledgeable and friendly staff.

This may seem to be at odds with some accounts of incidents reported on by members of the protest camp that has become a permanent feature opposite one site on Harvil Road. Most of these have involved security staff and it’s quite clear that protection of the HS2 sites is paramount evident from the use of the court injunction to prevent trespassing and further protests.

If the construction practices here can be replicated across all the HS2 sites in the area, then that is about as good as we can expect from these sites. They are going to have a huge impact on the area, but if we cannot get the sites removed then this is the standard we should be aiming for.  However we know HS2 contractors are under cost pressures and some of the things Murphy have done do cost more than usual, so it is important we keep the pressure on HS2Ltd for this level of quality across all sites. HS2Ltd claim that they are in fact driving this level of quality standards.

We are pushing for direct contact with the contractors and main sub-contractors. Our experience is that they are generally much more knowledgeable and helpful with a keen interest in genuine community engagement which is a real contrast to the frustration we experience with HS2Ltd.

Doreen McIntyre,  Lottie Jones, Phil Taylor (June 2018)

Please see the slideshow below of pictures taken by us on our visit:

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