Holdfast Training Services Trial Blog

Things are picking up on site. The excavation has now been completed on the first to piers and the piles are being broken down. The hydraulic cropper arrived on site (after much delay it ended up being shipped in from the UK), and it has promptly fell on its arse. It works fine, too good really as it is mangling the reinforcement and strand within the piles that need to be tied into the pilecap reinforcement. There just seems to be too much congestion in the pile for it to work as intended. The helical cage combined with the strand and the normal 24mm bars seems too much for it. The photos below show what the pile cropper in action and what its first and fourth attempts produced. There was an improvement in the technique, but it was still causing too much damage from a QA point of view.

Below is the pile that was broken out through a combination of a rock breaker on the backactor of a LWT and men with jackhammers. I know Joe had great success with the cropper but it seems that the combination of high grade concrete (should be 50MPa but in 28 day crush tests its reaching over 70MPa) with lots of reinforcement is too much for it.

The excavation has been stepped back at a 1:1 bench with a further stand off equal to the depth of the excavation (to make a 1:2 slope). The same geotechnical consultant that is certifying our crane and piling pads has looked at this and he seems more than happy with this for normal traffic. We’ve looked a lot more closely at the loading for the 80T rough terrain cranes that will be lifting the forms into position. Things still seem good when considering the bearing pressures. The biggest problem seems to be passage of information to the guys doing the work on the ground. When barricading was put in to maintain this stand off all was good. I then found out it was moved to get an EWP in closer to the edge for access to something. It seems the workers thought the barricade was to prevent falls into the excavation, and the supervisor hadn’t passed on it was for standoff. Its now been covered in the daily prestart and I’ve spoken with the crew on the ground too. I’ve spoken with the geotechnical consultant about the benching and how long it will be safe for, I’m anticipating a few questions from John on this….

In other news there are still dramas over steel reinforcement in the headstocks. The cages for the columns have started to get tied by the steelfixers. The formwork for the headstocks still requires modifications and I’ve been in touch with the designers Bonacci about modifying their drawings. One of the big questions is how to remove the support frame around the column once the headstock has been poured. This might have to be another blog on its own.

I’m now going to elaborate on what happened on Tims site for the civils that maybe don’t read the E&M blogs. All this information is from either Tim or the John Holland internal safety alert system (JHET). Its been raised on my site and across John Holland as a whole, its of particular relevance as I have temporary excavations currently in place and the upcoming formwork installation too. It seems to be a good way of passing the information and making sure that the group as a whole learns from mistakes – I’m not sure what the others in Oz think about this? Is there an equivalent system on Crossrail?

Description of incident:

A Subcontractor concrete work crew were pouring concrete in Zone 2, Basement 2, Pour 1. During this work, the Bondeck and supporting formwork/falsework, partially collapsed resulting in approximately 8 m3 of concrete in a 40m2 area to fall through deck to lower level. The concrete work crew identified the failing deck and evacuated the area prior to collapse. No personnel were below the deck at the time and there were no injuries as a result of the incident. The site was immediately evacuated.

Contributing Factors

• 32mm of rain overnight prior to the incident affected the stability / integrity of the base plates and tombs on the batter between B2 and B3.
• The Formwork Engineer issued Formwork certificate 5 days prior to the pour, providing opportunity for external factors to change or affect the integrity of the formwork structure.
• Temporary works procedure not implemented adequately

Lessons learned

• Where formwork is supported on two types of ground bearing (e.g. natural earth batter and slab on ground), specific design documentation, inspection regimes and certification processes need to be implemented.
• When Engineer certification is provided for temporary works well in advance of activity and bearing on non-unified material, due to unforeseen delays with potential for alteration, modification or damage to the temporary works, a re-inspection / certification process needs to be implemented

I’m now back! After a reasonable period of time offline in the blogging world here is blog no 4.

My work has continued at breakneck speed along C620, hence the lack of blogs, and for those who can recollect blog 3 I had just finished the piling and had started the excavation of the foundations.

So here is a shopping list of what I have facilitated or directly completed over the last couple of months:

17 piling platforms excavated, backfilled and CBR tested.
170 PC RC piles, positioned, driven, tested and cut.
8 Steel H-Section piles, positioned, driven, tested and cut.
28 permits to dig completed.
Excavations set out.
1000m3+ of material excavated.
Heights checked.
22 service ducts and water mains positioned, excavated and placed.
136m3 of blinding poured.
Heights checked.
170 PC RC piles marked and cropped to expose rebar.
8 Steel H-Sections cut and modified for a deep foundation in tension.
Over 200m3 of groundwater pumped out of excavations.
Over 200 nails positioned for setting out.
Reinforcement steel fixed, positioned and checked against RC drawings.
Heights checked.
56 earthing cables set out and welded.
Over 1kM of shuttering placed.
Height, vertical and horizontal cover checked.
Foundations blown out.
69 individual bolt pads positioned.
Heights checked.
500m+ of chamfer filet set.
Heights checked.
11 notification to pour forms completed.
581m3 of C32/40 concrete poured.
60 sets of cubes taken.
Heights checked.
Shuttering struck.
Excavations backfilled.
1 large QA folder still to be completed!

The last base was poured today and I now have over a week’s worth of QA paperwork to complete for the whole section. 3 of the steel trestles have been constructed onto the early bases and they all fitted perfectly onto the bolt pads – so far, so good – fingers crossed for the rest!

So what have I learnt? Loads of stuff! But for now ill conclude the piling episode with a few remarks as I know those who followed my previous episodes cannot wait for the conclusion?!

As you will remember many PC RC piles broke, steel H-Sections were used as replacements. This was the focus of TMR1 and as some of you won’t be lucky enough to read that particular gem so I will expand on my observations.

Risk.

The risk within the piling sub contract was shared reasonably effectively between Graham Construction and Balfour Beatty Ground Engineering (BBGE) and reads ‘‘The subcontractor has not allowed for overcoming man-made or naturally occurring obstructions (whether they are below ground, surface or overhead) which impede, or deflect the Works, or result in them failing to achieve the design and/or specification requirements. Any additional time and costs associated with overcoming or attempting to overcome such conditions (including but not limited to set ups, displaced and/or damaged works, replacement and/or additional works, lost consumables, and damaged plant) shall be in variation. The subcontractor however has allowed for the cost of 30 replacement piles on this occasion. Any further replacements will be a variation in accordance with this clause. Should less than 30 replacements be used the cost saving shall be shared by both parties’. This figure of 30 piles was agreed by negotiation as initially BBGE would only accept 10 breakages as part of their standard contract. It still proved an underestimation as these replacements had been consumed during the first stages of the operation whilst piling for the RC storage silos. Subsequent replacements were charge at the agreed original pile cost calculated by the length required: 18m and below at £450 per pile, 18m and above £620 and driven via a variation order. All the piles for C620 were 18m and above and therefore the replacements were charged at £620 per pile with the additional cost of pile testing at £120 per pile (1 in 10 tested). This risk of breakages had been identified by the Graham design team from studying the borehole data and hence the 30 pile float had been negotiated. This risk and associated cost was covered by Graham Construction.

However BBGE also took a risk within the contract. The calculations conducted by BBGE detailed the design depth for the piles to achieve the specified working loads across the various areas of the site; the price was quoted from these calculations. However the piles were installed to a dynamic resistance, or set, calculated using the Hylie formula (less than 25mm per 10 blows) and therefore the actual length varied from those suggested by the static calculation. The additional sections required to achieve the extra depth and set, beyond the calculated and quoted for depth, were at a cost to BBGE. In addition, BBGE priced the contract on the number of piles driven at the calculated length, not on site time. The re-organisation of the piling during and after the breakages resulted in an amount of standing time charged at a set rate, higher for the first hour and then reducing for subsequent hours. This time whilst at a cost to Graham, was at a greater cost to BBGE as the greater profit for them is in the driving of piles succinctly and quickly. Whilst the rigs are standing the BBGE profit is reducing and it also delays the rigs from moving on to other sites where the more profitable piling can continue. When looking at the number of breakages across the whole site coupled with the additional lengths required on a significant number of occasions, it is quite possible to envisage a reduced profit margin for BBGE.

I feel that the risk was actually well shared by both parties. On the surface it appears that the majority of the risk was held by Graham with the low number of potential breakages (30) written into the contract but on closer inspection of the ground investigation data it was clear that deeper piles would likely be required and hence a risk to BBGE.

Ground Investigation.

A large amount of ground investigation data was available to both the designers (HBPW) and BBGE as the pile designers from a series of surveys conducted at various times across the site from when it was reclaimed from the sea in the 1990’s. From the vast amount of data available BBGE took the unusal step of not using a design borehole to design the piles but used the actual borehole data. Whilst not particularly risky the boreholes used where not, in my opinion, the ‘worst case’ boreholes that in my logical mind would choose. In addition not all of the data was referenced by the main designers for BBGE to use to design the piles and this missing data contained the worst case boreholes, including the one closest to the area where I broke all the piles that had a 2m deep layer of chalk made ground. Has all the information been thoroughly considered it is likely that the piles may have been redesigned at a deeper depth, costing BBGE less and invariably saving on the number of breakages. This in turn would have led to a reduced cost to Graham and the steel section solution being reached earlier, if not from the outset.

The ground is a risk. The importance of GI cannot be underestimated and whilst in this case the problems were not from the lack of information, as is often the case, but from a lack of exploitation of the available data.

Apologies for the long blog and the lack of pictures. My iphone slipped out of my pocket on Thurs afternoon, and as is always the case with sods law, got immediately run over by a dumper with all my exciting photos. Happy with that.

But first thing first.  A bit more on how projects develop in Projects and Mods.  

The Process.  As you read in my last blog the BP process goes from Appraise –> Select –> Define –> Execute.  The precursor to all this activity requires the that customer, read platform, submits a request for work (WFR) form which is considered by the Project and Mods Team.  Should it be deemed suitable the proposal is considered in a screening study.  This identifies in very broad terms who the stakeholders are, how much, how long it will take, possible options…..  This will then define how the project is taken forward:

• C1 – Separate Appraise, Select, Define and Execute phases.  (High Value and / or complex)
• C2 – Combined Appraise / Select and separate Define and Execute phases.  (Medium value and a number of options to be considered.)
• C3 – Combined Appraise / Select / Define and separate Execute phase.  (Low value and simple e.g. like for like replacement)

Responsibilities.  Outside the BP structure Costain Upstream is responsible for delivering the screening study, Appraise and Select phases.  Wood Group PSN is responsible for the Define and Execute phases.  This split responsibility is mirrored in BP with there being a front end single point of accountability (SPA = project engineer) for the screening study, Appraise and Select phases and a Define / Execute SPA (me).

Funding.  There are various sources of funding available to the project teams: operational expenditure (OPEX) and capital expenditure (CAPEX).  OPEX is used to fund the screening, Appraise and Select phases and CAPEX is used to fund the Define and Execute.  The OPEX budget is generated and owned by Projects & Mods.  The budget is bid for annually by considering planned work on assets and adding an allocation for emergent work.  CAPEX expenditure is controlled by the operators and it is made available to a project once a financial memorandum (FM) is approved and an approval for expenditure (AFE) is agreed by the partners.  The FM approval is required prior to an AFE being agreed.

PROJECTS – THE OLD

Mungo Rescue and Fire Fighting Services

This is now in the final throes of the Appraise / Select phase before going forward into Define / Execute phases, at which point the responsibility for the project is passed to me.   The next stage will be the submission of the FM and AFE.  As a warm up for the submission of these documents I was ‘invited’ to present to the partners (First Oil and JX Nippon) so that they understood the need, schedule and cost.  A hugely enlightening experience, dealing purely with the commercial side of the business.  

Miller Helideck Lighting Trial

When I wrote my last blog I hadn’t appreciated that there was no money available to install the lights on the Miller.  A hugely frustrating place to be in, considering that both the Logistics and the Safety and Operational Risk (S&OR) business functions were screaming out for the job to be done.  After much toing and froing and a delay of 8 weeks a lump of cash was found.  This allowed the project to get off the blocks.  I was amazed to be on the receiving end of huge amounts of pressure to catch up 8 weeks on a 9 week project.  Needless to say a face-to-face meeting squared that one.  I still expect to get a note a week ‘asking’ me to make up the lost time!

The accelerated timeline that this is already on is starting to create problems.  As a part of the Define / Execute Wood Group would typically confirm and specify details of selected equipment as the design authority.  Because of the drive to get this offshore, the Define stage has been completely bypassed.  This means that materials identified (not specified) by Costain in their front end work is being used to draw up bills of materials.  (Specification sits outside the requirement placed on Costain.)  So at the moment I’m attempting to move a project forward in which Wood Group is uncomfortable to progress as they have no specification to work from and they are unwilling to take the materials identified and work them into specifications.  Having to sit down and hold hands to even get a rivet on a BoM. 

PROJECTS – THE NEW

Andrew Sea Water Filter Failure

So the 2up boss came into the office and said something like ‘come with me boy!’.  At which point I was the subject of a number of commiserative glances and found me feeling like I was back at primary school and had been summoned by the headmaster for a gentle caning!

Turns out one of the two sea water filters on the Andrew has suffered unprecedented corrosion and was on the verge of failure.  Not a huge concern today as the platform is not producing, however, once the platform comes back on line there will be no redundancy.  Coupled with limited understanding of the corrosion mechanism there is a risk that the second filter may fail cutting off cooling water supply to the platform.  This will result in a halt in production.  

Initially a thinning of the filter vessel wall (Filter A) was identified as a part of a routine inspection.  A significant thinning from 19.3mm to 8.3mm was recorded between Oct 13 and May 14.  Further testing a week later identified a thinning to less than 2mm.  At this point the vessel was isolated and the complete seawater duty run through Filter B.  There has been much flapping as corrosion rates of 1mm / day are unheard off.  As yet no similar corrosion has been seen on the B filter, however, on-line testing is ongoing to confirm the condition on the B filter. 

There are two simultaneous streams of work ongoing to deal with this concern.  The first being run by the asset is a repair of the existing 316L SS filter to bring that back into service.  The second piece of work is to procure a replacement filter.  There are at least four courses of action associated with procuring replacement filters:

• A – procure 2 x replacement filters made from super duplex steel.
• B – procure 1 x replacement filter to replace Filter A.
• C – procure 1 x replacement filter to replace Filter B, assuming that a Filter A is repaired and coated.
• D – do nothing (other than repair).

To date my involvement has been limited to attendance at option studies.  At present the balance of effort is on progressing the repair.  I am awaiting a WRF prior to initiating a screening study. 

ETAP Sand Management

When the ETAP started operating the hydrocarbon flow line did not contain sand.  Recently production has recovered large quantities of sand that is causing considerable damage to the produced water reinjection (PWRI) system.  The PWRI system is used to maintain the well pressure, therefore, has a direct impact on production.  (After bringing the pumps back on line the minimum failure interval is 1 day and the greatest is 6 weeks.)  

The work scope is broad at the moment, but is looking at increasing the residence time of the hydrocarbons in the HP & LP separators and installing cyclones to remove sand from the process completely. 

My involvement at the moment is limited to arranging an offshore survey.  Normally a reasonably straight forward process, however, I’m having to submit waivers to divert from the normal processes.   The risk of ‘fast-tracking’ the process is that the platform won’t be properly prepared for the visit and the survey will fail to meet all objectives, wasting beds on the platform – a cardinal sin.

ETAP Electrical Controls Upgrade (EECU)

I’ve had sight of this one for about a day now.  It should turn out to be educational.  It is mainly a subsea job (so outside the scope of Projects and Mods) but there is a topside interface that needs to be engineered and managed. 

As far as I have been able to figure out, there is a legacy low insulation resistance (IR) problem with the power and control cables that run from ETAP ‘mother platform’ to the surrounding fields.  The low IR is already starting to affect one field. (not sure how yet)  The EECU is a proactive work stream to prevent similar problems occurring on other ETAP fields. 

I went offshore this weekend to get a feel for the platform and to complete a detailed recce of all my jobs. I was offshore with another SPA, and we went round the platform and explained things to me. He is a structural engineer by degree so he did his best but he was a bit put of his depth.  It was kept to an idiot’s guide level of explanation but it was very useful nonetheless. I managed to steer the conversation away from steel and concrete so we covered all the important issues such as chemical processes, piping arrangements, electrical single line diagrams, safety mechanisms, utilities including use of gas turbines fire water, potable water, storage of fuels and chemicals.
I had a detailed look at the jobs I am likely to encounter such as the Lifeboats, HP Cooler Replacement, Cabin Retrofit, and DC Charger Replacement. I also looked at some of the jobs that Imran is desperately trying to palm off on me. All in all, I feel like things are getting really quite busy and people are ready to trust me with much more responsibility.

The first thing I noticed was how seriously they take H&S, and quite rightly too. They termed it an open environment and it was where every crew member felt it appropriate to approach another person on the platform and point out any issues, or potential issues. They called it a Time Out For Safety (TOFS). It was good to see how the different systems work but I did notice that the permit to work system does slow things t like too many permits open at once so work can end up being stymied.

Jobs for the boys…

There are quite a lot of similarities with working in the military that would make ex-Army a good fit for working offshore:

Travel.  Be ready for hurry up and wait, it was like travelling with the RAF.  I had numerous delays but without any good reason.  I was almost bumped off the flight at the last minute only to be told to turn up on the off chance.  What should have been 70 minutes of flight time (50 in a fixed wing plane and 20 by helo) took 6 hours.  However, the airhostesses are not overweight men in sandy coloured coveralls.

Workers.  The average worker is just like a career sapper but aged 40 – 60.  They like doing what they  know and no more.  You have to double check on them and make sure they’re actually doing as they’re told.  The more senior guys on the platform are like the NCOs and WOs.  These guys are dynamic and get stuff done and know what to do through heaps of operational experience.

Routine.  Work routine was like being on operations.  They work long hours and have a bit of down time in the evening.  They then have time off to play hard.  A typical rotation is two weeks on, two weeks off.  The platform was full of workers and not a place you’d want to be without a busy job.  A bit like being stuck in Bastion longer than you needed to be.

Food.  The food was the same as being on operations, Aramark get everywhere.  It’s no wonder the Army can’t get a good deal by playing hard ball with Aramark because they must have much bigger contracts to worry about.

Pay.  This was a huge difference; the guy I was with was getting £90/day extra for being out there.  That would mean he would only need to be out there for 34 days to get the same as our operational bonus for 7 months (not taking into account tax).