Archive
Back in the game!
Well I made it back to London this week and back to work on Monday. The foot is on the mend and I have now progressed to the B3 Cbt Engr post final exercise hobble! All of my x-rays have now come back fine and I am now encouraged to walk but it is still a bit uncomfortable. It takes me twice as long to get to work as I have to walk slowly to the bus stop and site office but hopefully it will be back to whacky races on the bike again soon. At least my foot looks like a good bit of engineering now with it’s 3 titanium bolts!
I am now office bound for a few more weeks until I can squeeze the hobbit foot into my work boots but I am still covering the utilities installation. I have picked up a few technical issues that need sorting out before we can finish off our drainage. We are planning to pipe-jack a 450mm concrete pipe 70m under Battersea Park to the mains sewer. Our sub-contractor (O’Keefe) have a sub-sub-contractor (Perco) lined up to do the work and as far as we were concerned they had a plan at least pencilled in. I was a bit concerned to see an email from Perco asking O’Keefe to clarify the ground water level as the latest and closest borehole information didn’t show a GW strike in the first 10m yet another borehole further up the site hits water around 3m BGL. I found this latest borehole data very unusual as around 20m away we had been striking water at around 3m in the drainage trenches and it was p*****g in! So today I have been doing my own desk study and gathering previous borehole information that is on Aconex-our data sharing site and getting the latest data from the client’s representatives. Low and behold all previous boreholes along the south of the site strike water at around 3m BGL either in the River Terrace Gravels or Alluvium Clay above the gravels. The area at the south end of the site is a bit unusual as it was a reservoir with filtration beds in the 1800’s and the back fill has been a variety of materials. I think the latest borehole didn’t record the groundwater accurately for perhaps 2 reasons: they were using water between 1-5m to lubricate the cable percussive borehole machinery, or the fact that we were dewatering our drainage trench around 20m away at a rate of 7L/s. Either way it doesn’t look like a good borehole to use for design (John-triangulation I hear you say!). I am also a little concerned that Perco have said that they would have problems conducting pipe-jacking with a heading in wet granular soils due to the likelihood of ground loss. I have put my findings to the senior engineer at Buro Happold who has been designing the drainage and hopefully he comes back with some advice on the design borehole that Perco should be planning the works to.
Around the rest of the site progress has been made and here is last months time lapse video:
http://vimeopro.com/user25873713/battersea-power-station
In the Cam 96 video you can see my retaining wall for the road going in by the railway arches. In the bottom left the cofferdam for the pumping station has been excavated and propped using a Mabey prop system and finally the concrete rings have gone in but I missed that excitement. In the top left corner John would be getting excited with the props, waling, thrust blocks and excavation of the cofferdam, so far the sheet piling has moved 20mm and there is only 5mm more allowed. We are not sure how accurate all the monitoring measurements are though because someone has hung a water pipe on the wall using the survey targets! The piling rigs are still working hard and the sub-contractors are still constantly arguing over pile mat handover and areas to work in.
Greg would have a field day!
The last blog saw me having a few issues identifying the contract that was in place for the £1.2 million of waterproof membrane which we will be spraying in permanent works beginning on the 3rd Jun 14.. Turns out there wasn’t one…
I am determined not to use this blog to drip about the complete mismanagement of this process…I’m beginning to bore myself. So instead I will detail some of what I’ve learnt and try to tease out what John would call, ‘CPR gold’.
1. Statement of Requirement. The specification designed by the MottMacDonald Ltd is linked here. 16 Section KW20 Materials and Workmanship Specification – Spray Applied Waterproofing Membrane Systems for SCL Works
The performance requirements are at para KW20.1301, and Table KW20-03 in the appendix. In outline they pertain to bonding properties, permeability, crack bridging and flammability.
2. Preferred suppliers. In the beginning, 4 chemical materials companies were under consideration. I hesistate to use the term preferred suppliers, as there is a slight nuance here.
a. Subcontractors. Blokes doings things with kit and materials. The Joint Venture will invite subcontractors to tender for work, using this website. Designed for use at the Olympics, it has become industry standard for major capital contracts to ensure transparency. Subcontractors then accept the invite and are added to a list ahead of a commercial comparison, eventually leading to a subcontract, in this instance in the form of NEC.
b. Suppliers. Just stuff. A materials requisition report is raised from BFK and sent to a list of suppliers. This process is much less transparent and very much favours older, larger, richer and more established companies. It follows a process reliant on old contacts and who we have used before, combined with a quick Google search. We let them know we are looking, and suppliers then tender for the work, are compared, and a decision is made culminating in a supply order.
For the waterproof membrane, we are in a very grey area. In essence, we are ordering material alone, which should put us in point 2b territory. However, we are also hiring their machine to apply it AND getting a techical expert to train us. This training really should stray no further than the classroom, but he is already operating underground…applying the material in a trial tunnel…that is in fact going to be a cross passage…that will be inspected and signed off as permanent works. This strikes me as a professional service and one which should be protected by the assurances commensurate with a subcontract.
3. Commercial Comparison. The four chosen suppliers then underwent a commercial comparison, the output of which is here: Commercial Comparison. The churn of people in this place is such that the people that were involved have all left, so I have tried to pick out the decision making process (I’ve hidden the names to product their commercial modesty so if you’re having trouble sleeping, play along at home and see if you can work out who we went with.
a. Specification. Clearly, the first criteria test is if your product meets the spec.Although all state they can, one was unable to prove it. The eagle eyed will note than one actually does not meet the spec on permeability. His waterproofing is not waterproof which you would have thought would have harmed his chances…
b. Experience. Previous case studies are all important, and if you can say that your product has been used successfully on previous high profile projects, it will stand you in good stead. Additionally, the tunneling fraternity is quite small so it is likely that some of those making the decision will have worked on those jobs. Definitely the case here, and you will note on this critieria, one supplier is the clear winner.
c. Cost. I remember Greg saying that the cheapest and most expensive tenders are often stripped away straight off the bat. In this instance the most expensive is prohibitively so, and as such put himself out of the running. Although the original budget is lost in the mists of time, we are now looking at projected costs for this work for the purposes of the materials requistion.
d. Add Ons. In order to further mitigate risk, the supplier may offer supervsion, training WITH accredition and ongoing technical support. For us here, this is critical. There is very little knowledge on the product or the equipment.
How did you get on? Hopefully you all went with Supplier 3…BASF with MasterSeal 345… because we did and its too late now. The irony is however, we’d already signed up to the automated machine…the Logica….BASF owned which can only use the BASF products so it seems this process was slightly moot.
In other news,
Thermal Trials. The thermal imaging trial has rolled out on site this week. Feedback was positive, and having delivered a number of ‘toolbox talks’ it is reassuring to note that much like your average Sapper, the miners were really only interested in how expensive the kit was. I am awaiting data feedback, but check out this footage of the shotcrete being applied to the crown of a tunnel.
Note:
1. The shotcrete begins to react in the air immediately on leaving the nozzle. Note, the reaction as it accelerates when on the surface…its is easy to see the contrast with the cooler concrete, which will immediately identify concrete which is not curing and thus areas of risk
2. The rebound (waste) actually amounts to quite a bit. In the dust of the tunnel this is often not noticed to such an extent.
Rugger. I turned out for the Joint Venture v CrossRail(and ringers) at the hallowed turf of the Honourable Artillery Company ground in Moorgate. After some pretty fruity tackling interspersed with moments of sublime and ridiculous, we ground out a 10-5 victory. Check out the first 5 mins…you will note my slick hands, sublime running lines and stonewall tackling are mainly obsured by a fat bald bloke in a wifebeater.
Holdfast Training Services Trial Blog 
