Holdfast Training Services Trial Blog

I’ve now been on the Peters Village project with BamNuttall for a couple of weeks and am slowly working out what is going on…we’re building a bridge!

The Peters Village project is a new community consisting of 1000 houses, schools, shops and so on. It is expected that in time it will grow to 5000 houses and as a result the local area infrastructure requires a large uplift. BamNuttall are responsible for the local area infrastructure but not the housing development.

The project office sits on the East side of the river, however the bridge section of the project is run from the West. Currently the site resembles a complex obstacle plan and is covered in a foot of mud making it look more like the Somme than a building site.

Project Overview

The project can be neatly split into a series of sections each with a dedicated team:

On Site Roads – These will feed the new built community and incorporate some ground preparation for the village.

Off Site Roads – 3km of road network to link the village to the surrounding area.

Medway Valley Crossing MVC – 150m pre-stressed, post-tensioned, cast in place river bridge

– 30m pre-stressed, pre-tensioned bridge over a live rail line

– 500m road and deep drainage linking the two

Kent council scheme proposal

Thankfully I am in the team responsible for the MVC, which will expose me to a much broader range of tasks and engineering issues. The river bridge sits on the critical path for the MVC section of work and that is the main focus of attention at this stage. The Rail Bridge has, and continues to, slip further behind regarding the start date, however, it has so much float in the schedule that there is no immediate concern.

Currently there are two key areas where efforts are being focussed, these are:

1. The False Work Jetty

There is a requirement to maintain a 20m navigable channel open at all times. In order to achieve this a jetty will span out of each bank parallel to the main bridge; these will support the cranes required for construction. Directly below the main bridge a second jetty will be constructed to support the bridge false work. At present we have the west side crane jetty complete and are halfway through piling the west side false work jetty. Finally, two cofferdams will be constructed (the first started today) in order to provide access to construct the main bridge piers. Below are a couple of images that will hopefully add clarity to my poor explanation.

Crane jetty’s, false work Jetty’s, cofferdams and bridge piers

Late stages of construction, false work removed

View from the end of the west crane jetty. The closest four piles

Mark the corners of the cofferdam. Taken at high tide.

2. Consolidation of Existing Ground

The ground profile across the site is clay over laying chalk with a thickening alluvial layer as you near the river. Currently the site slopes towards the river and is anywhere from 4-8m below the required formation level. Chalk is currently being imported from the cross rail tunnels to build up the level of the site and also to surcharge the clay and consolidate it. In order to increase the speed of consolidation band drains have been used. It is predicted that it will take at least six months to reach the required level of consolidation and a number of techniques are being used to monitor it. I will expand on this in detail in future blogs.

In Other News

Remember that moment on Ex Cofferdam when you messed up your calcs at 0200hrs on Wednesday morning and you can’t understand why no pump in existence is capable of emptying your hole…no…maybe that was just me, but fear not because we have a little blue pump on site that could not only deal with Ex Cofferdam but is actually callable of pumping out a rising tide on the Medway!!!!!!!!!

Thankfully a concrete plug now seals the end of the sheet pile wall and we’re not wasting diesel trying to fight nature any longer! I’m not sure if the poor lad monitoring the pump had been told to do it as a wind-up or not but as it was my third day on site I just smiled!

And Finally…

In case you were wondering, yes it is possible to eat an entire Soreen loaf, Mars Bar and drink close to a litre of Coke in the time it takes to drive an 18m pile into the ground. Should anyone wish to marvel at the evolutionary wonder that is our 110T crane driver please feel free to get in touch to arrange a private viewing.

ICE attribute E3 (I am sure E&Ms will have something similar) requires us to “Demonstrate sound judgement on statutory, contractual and commercial issues in relation to your area of responsibility.”

On completion of AER 1 I was naïve enough to believe I understood enough and could crack on with “doing stuff”.  It turns out I was wrong (Neil – one for you).

There is loads of other, seemingly small, stuff that you need to understand to really appreciate the commercial implications of what happens on site.

On my site we’re just 6 weeks in and our sub-contractor (PCH) is over 2 weeks behind schedule.  According to their recovery schedule they should be pouring the first section of the basement raft slab on Monday.  That won’t happen.  Primarily because they still haven’t ordered the top rebar, let alone had it delivered or fixed it.  PCH is staring down the barrel of a non-conformance report which looks very bad for the company.  So naturally they’re looking everywhere to find someone else to blame.  Therefore we (the main contractor) must ensure we’re whiter than white.  We cannot be made to look responsible for their lateness.  Therefore there is a huge push to ensure that all the RFIs are answered, designs approved, drainage and water-proofing inspected and tested, etc…

This has come to the fore thanks to a problem with the lightning protection.  The installer struggled to reach the required resistivity (one for the E&Ms) and as a result had to come back and redo some work.  This isn’t the end of the world; they can do the remedial work around the steel that has been laid.  The problem that was highlighted is that the lightning protection package manager hadn’t told anyone there was a problem.  So the construction manager asked the question “what else don’t I know?!”

The problem is communication.  We all sit in an open plan office in a large porta-cabin (like TFH HQ for anyone that ever saw it) and no one talks to each other (like TFH HQ).  But this lack of communication could have led to a “get out of jail free” card being given to PCH.  So we’ve implemented a severe measure:  each day at 1700 the engineers and the site supervisors get together and talk about what happened that day, what should happen the next day and thrash out any problems.  It’s not new, it’s not clever, it’s not quite an O Group but it’s not far off.

In summary:  There is nothing discrete, everything that happens on site carries a commercial implication.  Therefore it’s key that I keep in mind how all the parts are interconnected as any delay could cost someone loads of money!

Slightly early this week and a bit dry, so here is a gratuitous digger shot:

AIRBORNE!

UPDATE:  It turns out PCH (the sub-contractor) were having some cash-flow problems.  So McAlpine (the main contractor) have bought the steel direct on their behalf and will deduct the sale amount from their payment.  This should speed up the process and we’ve managed to secure a better rate!  It’ll start to arrive on Wednesday.  Guess which lucky individual gets to count it all when it arrives…!