Holdfast Training Services Trial Blog

Well I haven’t blogged for a while as I have been at home feeling sorry for myself after my other foot operation.  I have now progressed from crawling and hopping to now hobbling around the flat and I am being a bit more productive.  The first week involved co-codamol induced tiredness and my foot feeling like it was full of molten lava so I didn’t achieve very much except a few odd jobs and lots of watching Grand Designs, Homes Under the Hammer and Building the Dream.  Just to prove I haven’t been off skiving here is the foot after a week:

My highlights of the week were the arrival of the postmen and Ocado delivery guy.  One of which bought me a very exciting get well present from a friend.  Helping to maintain my engineering practical skills and entertaining me for 2 evenings and 1 morning, I give you the Lego Campervan:

Hours of entertainment and great attention to detail inside it.  I am glad the age was 16+ as I was surprised how long it took me!  The engineering challenges were organising my stores area without taking up my whole living room and not lifting it up by the roof which falls off under its self-weight!

I have also been keeping an eye on my Carillion emails and it doesn’t seem like I am missing anything too critical.  The most exciting email has been regarding the banana shaped HV slab.   The plan was to knock the wall to Battersea Park Road down, install a GRP housing on the slab for the substation, insert the substation equipment into the housing and connect the cables.  However, the Battersea Power Station Development Company (BPSDC) who are the client have been unable to knock down the wall as TFL will not let them close the footpath.  The doors of the GRP to the substation  were meant to open outwards to where the wall was but seeing as it is still there the plan had to change.  Scottish and Southern Electric (SSE) have now decided to get a different GRP housing which has 2 sets of doors on each side.  It sounded like a good plan until I read the next email which said that the housing was bigger and would overlap the slab by 400mm!  So the client has requested that Carillion extend the slab to fill the void.   It sounds like it is going to be a time consuming and expensive work around for not being able to knock a wall down when expected.

Tomorrow I am back off to hospital for my X-rays and hopefully I will be off crutches by the end of the week.  If all is well then I will be back to London on Sunday to go back to work on Monday.  It will probably be another 3 weeks before U can get my work boots back on so I will be confined to the office for a while.  I hope to do a bit of talking to the H&S manager and the Environmental and Sustainability person.  I might also try and get a day shadowing the Temporary Works Designer for Carillion who works at their main office.  Are there any other useful things I can be getting on with before they pile my desk with paperwork and tasks that nobody else wants to do?

Blog No.3

My work continues along conveyor 620 and I am now following a fairly set process to complete the different foundations.
My last blog concluded with the piling almost complete (6x steel still to be driven) and preparation for the next stage of the foundation construction. So if I explain what I have done for Transfer Tower (TT)615 the process for all the other bases is more or less the same.

So initially I set the pile cut off point at 50mm (cover) below the finished top of concrete (TOC) level and cut the piles.

By extrapolating the information from the foundation GA drawing I set the level of the shallowest element (the 300mm main slab) included 50mm for the blinding, and excavated the entire base to that depth. This included 800mm of additional horizontal space around the outer edges for the shuttering to be subsequently placed. Once this initial excavation depth had been dug I then set out the slab ground beam locations and services that required further excavation (usually 500mm – 1000mm depth from TOC) , again including 50mm for the blinding. Once excavated the bases look something like this.

TT535 piles cut 50mm below TOC, excavation complete for slabs and beams.

I then cubed up the foundation, ordered and placed the 50mm blinding layer. Semi dry concrete was used to grade the slopes from the ground beams to the slab locations.

Once the blinding cured I set the level for the piles to be crunched and the steel exposed (usually 75mm above the blinding as the bottom cover is 75mm) and the rebar was then broken out. Once the steel was exposed the electrical subcontractor came in and placed all the earthing cables, welded to the pile rebar.

TT615 service pipes placed, blinding poured, slopes graded, piles crunched to expose rebar.

Using a total station I set out the extremities of the foundation, placed the nails, strung out the edges and sprayed the lines for the steel fixers.

The fixers then arrived and started positioning the steel reinforcing and I was checking the configuration, cover and heights.

The joiners placed the shuttering around the steel and again I checked the alignment and cover. Once the main body of the steel was completed I set out the positions for the starter bars for the various upstands and walls that come out of the foundation. These starter bars still need to be placed and the next stage will be to place the bolts for the structural steel, prior to pouring.

TT615 steel and shuttering in place. Starter bar locations for upstands and walls marked out.

This was the process I conducted for TT615. TT535 is awaiting the steel fixers and I am overseeing the excavation of Trestle 2-4 and the GTU as I write. It’s now a case of keeping the process up and ensuring I am 1-2 days ahead of the various teams of labourers, fixers and joiners spread across my section of work.

Reflections.

Services. The drawings do not include all of the services that may need to go into the foundation. I have only been caught short once where 6 service ducts needed to be placed into one of the bases and were not included in the GA. Luckily this did not require much remedial action and I discovered the omission before the blinding was poured (just). I did lose one of the smaller pads I had left for the construction of the slabs as the services went through it, but the fixers managed to make some steel chairs to support the slab steel as it was only a small area. Cleary this has a small cost implication as the ‘void’ will now have to be filled with structural concrete but as we are talking probably 1m3 I’m sure it will not be a problem when we come to pour.
Even when I found the drawing for the service ducts and was about to start the excavation I double checked with the electrical sub-contractor that it was in the right place. He agreed it was coming through the slab in the right place but the proposed alignment was incorrect. He then produced version A of the GA drawing (I was on G) and asked me to realign the proposed route as the electrical services had been designed to his drawing. On this occasion it did not significantly alter things but apparently this has happened on several occasions, with different drawing versions creating confusion and additional work. I now ensure that I communicate with all the service stakeholders prior to any excavation.

Speed and Accuracy. It surprised me just how quickly on completion of the blinding the steel fixers were all over the first base I had prepared. Having managed to place the blinding a day ahead of schedule I thought I had bought myself a little breathing time but I think everyone else thought the same. I set the nails and sprayed the extremities of the foundation and the fixers were on the slab before the paint was dry! I had a concern about 2 of the points appearing to be not quite square (on confirmation of the positions with a tape) and so queried the off sets on the GA. By the time the error was confirmed and I had the opportunity to re-shoot the positions the steel had been placed and the shuttering was being positioned. I spoke to the foreman in charge of the joiners and pointed out the adjustment required but as a couple of the holes for the shuttering had already been drilled in the blinding they simply ignored the new position and cracked on anyway.

Shuttering and steel out of position.

This left an approx 30mm extension in the base. I was not overly concerned as the cover was still sufficient, the alignment still straight and the edge did not tie into another structure. I highlighted the issue to the section manager who agreed with me and did not see it as an issue. What did surprise me was the lack of care shown by the joiners. The issue was highlighted in good time for them to only have to conduct 5-10mins remedial work. By the time the section manager had seen it, if he had decided that it needed changing the amount of remedial work required had significantly increased as all the shuttering was in place. Perhaps the joiners experience led them to know what would need changing and what wouldn’t but I’m not sure they have ever heard of the phrase ‘a stitch in time saves nine’. The experience has led me to be extra cautious when studying the GA’s. In this case it was difficult to see the error prior to them being set out and due to the speed of the follow up activities after marking out the foundation it proved difficult to actually prevent the subsequent errors. It subsequently took me half a day to set out the dozen or so nails for TT535 as I wanted to be 100% confident in the positioning after this experience.

Responsibility. The original section manager I was working to has moved to another site. This has prompted a reshuffle in the section, where the previous section engineer has moved up to section manager and one of the site engineers has moved up to section engineer. That has left 2 site engineers responsible for all the work across the site (bar the silos). Last week the other site engineer was covering a night shift as the steel subcontractor is significantly behind schedule and having to make up the time. This quickly left me as the only engineer in the section and although the section engineer was mucking in I found a lot of extra work on my plate and have now been overseeing the construction of another substation that I may blog about in the future.