Sunday 7 August 2011

Thames tunnel proposals for Coffey Street

On Tuesday 9 August at 7.30pm there is a public meeting at the Salvation Army hall on Mary Ann Gardens. A representative from Thames Water will be there to try and answer questions from local residents, and clarify the situation regarding the proposals for use of Coffey Street as a construction site for part of the Thames Tunnel.

I went to the public consultation back in June and spent a long time talking to the engineers about the proposals to try and understand the reasons behind them, and the implications for this bit of land and for the immediate area.

Since the site on Coffey Street is not intended to be one of the main drive shafts for the tunnel, nor a drive shaft for a connector tunnel, and because it is a fairly recent proposal, the amount of information about the scope of works and permanent structures that will be left is still fairly vague (I suspect Thames Water may still be working on this itself).

It's possible to draw assumptions from the huge amount of information available on Thames Water's consultation site, but I am also wary that there is nothing to be gained by repeating these assumptions as fact. Here's what I know so far, with the extent of my assumptions set out alongside.

The Thames Tunnel or 'super sewer' itself will NOT pass under Deptford. Assuming the preferred route is chosen, the 'super sewer' will run from west to east London (to Abbey Mills pumping station) mostly under the Thames. It will not come anywhere near Deptford.

(click to see this bigger)

However, the purpose of the tunnel is to pick up all the effluent from a number of combined storm overflows which currently flows into the river after heavy rain. There are two CSOs in this part of south east London which need to be connected into the main tunnel - one which runs from Greenwich Pumping Station to the foreshore at Greenwich, and one from Deptford which overflows at Borthwick Wharf. Thames Water's preferred method of picking up this effluent is to build a tunnel from Greenwich Pumping Station (the site just over the Creek on the right hand side) to Borthwick Wharf (numbers 21 and 22 on the map) and then to Rotherhithe where it will be linked into the main tunnel.

Thames Water is having to investigate alternatives to the Borthwick Wharf site because the Environment Agency is not keen on the proposal to build a permanent structure on the foreshore, and road access to Borthwick Wharf is restricted. Although building the shaft at Borthwick Wharf will allow spoil to be taken away on the river and some materials to be delivered that way, a good deal of deliveries will still need to be by road. Local residents have also objected to the proposal.

But because this shaft has to be built above the line of the existing CSO, there are a limited number of alternatives.

The Coffey Street site is being investigated as an alternative for the shaft. However even if this site is chosen, tunnel boring machines will NOT be brought to Coffey Street as some protestors are claiming. The site at Coffey Street is intended to be a shaft only, which will be dug to the depth of the existing overflow sewer, and will be used to make the connection between the new connector tunnel and the existing combined storm overflow.

The tunnel boring machine will be brought to the site at Greenwich. A larger shaft will be built here, down which the tunnel boring machine will be lowered. The machine will then tunnel its way towards the shaft at Deptford (at a depth of about 45m) and on towards Rotherhithe.

The only spoil that will be brought out of the site at Deptford will be from the shaft, not from the tunnel construction itself. All the spoil from the tunnel construction will be taken back to the site at Greenwich, where Thames Water hopes to put it on barges on the Creek and ship it on to the river. That having been said, the Coffey Street site will still generate a considerable amount of spoil during its construction, since the shaft will be about 45m deep and will take about a year to build.

I was told that the Coffey Street site will be active initially for about a year, while the shaft is constructed. After this there will be a period of several years during which the shaft will have to remain open for access, but no further excavation will take place. Then the permanent structure will be built and the site reinstated. I was told the entire process was expected to take about five years from start to finish.

One of the major complaints by protestors is that construction work will continue at the site for 24 hours a day, 7 days a week, for seven years. In its general consultation documents Thames Water has said that 'the main tunnel drive and reception shaft sites, and other key activities, may be required to be constructed on a continuous 24 hour cycle 7 day a week basis.' This site is neither a main tunnel drive shaft nor a reception shaft; whether it falls into 'other key activities' is not known. However the only work to be carried out here is the construction of the shaft, this will take about a year.

While the 'super sewer' will be about 7.5m in diameter, the CSO interceptor tunnels such as the one proposed for Deptford will be much smaller, some 2.2m to 4.5m in diameter.

The other main bone of contention, and in my opinion the one that is the most worrying, is what permanent works will be left on the site. Assuming that exactly the same facilities are needed as would be if the shaft was built at Borthwick Wharf, expect a building something like the brown one you can see on this rendering (there are figures on it too for scale - you can click to make it bigger).

The visual impact that the proposed work will have on St Paul's Church - one of Deptford's most glorious pieces of architecture and historically-significant buildings - does not even seem to have been given a thought. The church is already rather squeezed by the superhighway that is Deptford Church Street; thankfully the railway viaduct exists to mask the worst of the impact of the Resolution Way flats, but they still loom large and ugly over the top.

For a start, Thames Water needs to produce more detailed renderings of the permanent structure that it proposes to leave at the site. These renderings should include St Paul's Church, to enable the visual impact to be assessed without difficulty.

Finally, some aspects of the planned implementation process for the Thames Tunnel worry me greatly. If, as the government has indicated, the project will be not be subject to normal planning rules, then this should be another main focus of protests.

Last weekend's photocall organised by local residents brought a huge influx of Labour councillors to Deptford, which was nice. I'll be honest I was a little surprised at the level of support shown by councillors I've never even heard of and those I've heard of but have rarely been able to raise responses from on other local issues. Perhaps the presence of the deputy mayor had something to do with this show of support.

Whatever they are here for, it's all good and I commend the protestors on the extremely hard work they are putting into this campaign. It's important not to get distracted by bad science and claims about stinks and super sewers; let's focus on the facts that are available, and ask for further explanation of the situation pertinent to Deptford and this site in particular, to enable a useful debate and if necessary, a strong campaign.


Anonymous said...

Really enjoyed the post, thanks

Peter said...

I also went to the consultation and was told the following few things which could add a bit to your post:

1. I was told that there definitely wouldn't be 24 hour digging on the Coffey Street site, and that they'd work with the church to make sure their events weren't disrupted by noise. They also said that, while the timeframe is approximately three years, they'd expect the tunnel digging itself (ie the noisy part) would be a maximum of 18 months in total.

2. With the noise caused, they said that later on in the consultation, people/businesses could "pitch" their claim for compensation (eg covering the costs of double glazing etc).

3. Because the proposal was at an early stage, they didn't have any 3D illustrations. They also said that the buildings (from previous 3D models) were only ever meant to represent an example of the size/height of the building, and never the actual architecture.

Anonymous said...

isn't there some rather important archaeology somewhere in that area from the spectacular Thomas Archer rectory? Never mind the mind the living, have these people no respect for the peace of the dead in the nearby graveyard?

Monkeyboy said...

Well there are some really rather strict guidelines on archaeology, the Museum of London work closely with developers. Construction can actually give an opportunity to uncover the past, it’s the smaller jobs that ride roughshod over the regulations. Jobs like this should be fine, there’ll be archaeologists all over it.

As for the ‘never mind the living, what about the dead’, I’d turn that right around. The dead are dead, they’re corpses and presumably have been for generations, there is no one alive who will be directly affected, London is a crowded complex living city. The living should have priority, not some old bones - if in fact there is any threat.

Moving graveyards has been done for hundreds of years as London has developed, it’s not new.

Anonymous said...

It will be extremely sad if these works go ahead in Deptford's town centre. Brownfield site should be used rather than greenfield.
Works on this green land will affect two primary schools- particularly St Joseph's which is next door and therefore many of Deptford's children. The site is also close to the High Street, the leisure centre and to many residential dwellings. So, Monkeyboy, it will definitely affect the living!
Furthermore, the Church Street site is in close proximity to two listed buildings in a conservation area.
As many other local campaigns on this issue have said "Brownfield not greenfield".

Monkeyboy said...

Yes,that's what I said. I don't think disturbing graves from hundreds of years ago trumps disturbing the living. I'm all for finding the most appropriate site with the least disruption, it's unlikely there'll be a site around here that is disruption free. Doing nothing is not an option, we should not be dumping shit in the river in 2011.

Is there really a threat to a grave yard though?