Most construction managers are aware the construction industry is not, in Joe Public's eyes, 'green' - often despite efforts to press the environmental message home.
So why should CTRL be any different? After all, the project is massive, lies cheek by jowl with delicate areas of Kent's countryside, and now with sensitive London urbanites. Problems look inevitable.
But as Rail Link Engineering (RLE) environmental manager Paul Johnson is quick to point out, there is hard evidence that CTRL is already emerging as an environmental example for other projects to aspire to.
The project has recently been shortlisted in the Business in the Environment Awards, and has been described as displaying 'some of the best environmental standards we have ever seen, ' by the Environment Agency - despite some watercourse silt pollution incidents under very wet weather.
'In the future, when people are looking for a project to benchmark (environmental issues), I would like to think they would put CTRL at the top of their list, ' says Johnson.
On Section One almost 12M. m 3of spoil has been moved and recycled on site, and to restore the landscape, 350,000 native trees planted out of a planned 1.2M. The UK's largest archaeological and listed building relocation programme has also been undertaken.
From over 20km of planned noise barriers hundreds of metres have already been designed and built. Even the passage of dormice across the track has been eased by the construction of unique shrub planted landbridges.
But will the same standards stick for Section Two?
Johnson is confident they will, because the environmental standards RLE aims to achieve on the section are linked into an environmental management system (EMS) that provides a backbone to their plans.
The EMS provides a framework for achieving environmental quality during design and construction by environmental auditing or surveillance in the field.
'EMS makes sure our environmental commitments are properly implemented, ' he says.
However, Johnson is quick to point out that EMS is not just RLE's responsibility.
As on Section One, each Section Two contractor has its own EMS and a site-specific environmental site manager who meets regularly with RLE's own contract environmental advisor (CEA) to ensure a team effort.
'The CEA helps the contractors interpret the contract and acts as a source of advice, ' explains Johnson.
RLE's positive, proactive approach to environmental concerns is echoed in its approach to training contractors' staff.
'Some contractors' staff come very highly tuned (to environmental issues) when they are bidding, ' says Johnson, 'However, much of the later workforce is very transient and may not have the same level of environmental awareness.' So training is seen as vital.
Originally, training sessions were planned in the canteens on Section One contracts - until it was pointed out many of the contractors' staff ate elsewhere along the 74km of Section One.
This spurred RLE into taking the message directly to the workforce - via the Target Zero Environmental Incident Campaign truck.
'The Target Zero (Accidents) Campaign was originally initiated by health and safety, ' notes Johnson, 'but we saw it was the best way to deliver the safety and environment message on site.'
Agricultural land made up most of the Section One route, but the environmental team's priorities will change considerably with the advent of Section Two, which is as urban and industrial as it could get.
Problems are mitigated by the fact the route is mainly tunnelled, but an urban environment raises issues geared more around people than watercourses and trees.
'Mainly it will be the control of noise and vibration, dust and traffic and dealing with spoil, ' says Johnson.
Construction noise must be kept under control as part of Section 61 of the Control of Pollution Act, which requires the contractor to agree what types of plant he will use and agree acceptable levels of noise with the local authority.
This may include the provision of temporary noise barriers, secondary double glazing and even temporary accommodation for householders that could be particularly affected, 'It won't be so much of a problem in the tunnelling areas, ' says Johnson, 'but we need to be sensitive to local residents' concerns around the portals and the vent shafts.'
Groundborne noise concerns have also resulted in a 'softened' track design, adds Johnson.
'We are designing resilience into the track by specifying synthetic polymer pads into different parts of the system, ' he says.
The hard-wearing pads, that last up to 40 years, will damp the vibration resulting from the high speed trains passing over the track, greatly reducing the resulting noise in the few affected properties.
Tunnel portals and vent shafts are also being designed to minimise noise from the displacement of air.
One task that may prove more of a problem for the team however is disposal of vast amounts of spoil from tunnelling.
'It is more sustainable to keep the spoil on our sites rather than send it by road or rail to remote landfill, ' says Johnson.
Spoil from the Thames tunnelling contract, C320, will be used to build a development platform for Blue Circle Industries in a nearby disused quarry. Material from beneath Hackney and Islington will similarly be used to provide a development platform at Stratford and be a catalyst for a massive urban regeneration project. NL