Holdfast Training Services Trial Blog

The last two weeks as seen painstakingly slow progress on Dickson Rd as the site remains in the possession of the Civil team undertaking the stage 1 backfill. By fri last week they were about halfway to reaching the underside of the wingwalls and so far a job that was programmed to take 6 days (each side) is now looking like taking close to 4 weeks which will have a massive impact on the completion date of the end of Sept.

The positive side to this delay is that I have been far too busy with other things to focus on Dickson Rd much anyway. Last week was the usual EOM frenzy which refreshingly didn’t take my weekend away from me because the various deadlines all fell during the week. I have become rather wily in ‘hiding’ money in certain areas and cost codes just in case I need it which when pressed I can fully justify but hopefully when I don’t need to utilise it the gain column will look a little healthier. Across the 4 bridges neither one is projected to come in on budget according to the cost reports I produce but I am trying to err on the side of caution and hopefully when I can start closing some of these cost codes in the next couple of months the projected cost to complete can drop into the gain column to level out the cost a little and I am confident in getting all of the bridges within $50000 of the original budget. You make think that any cost over the budget would be bad but currently 3 of the bridges are projected to be $200000 over budget due to the realisation of a very tight budget that was set at tender. It is common knowledge that the JHG tender price os $550 million was about $100 million cheaper than the next rival because of their determination to win this project which was seen as a stepping stone in winning the NW Rail Link – JHG won the tender for the groundworks which is worth $1.1 billion and hope to win the subsequent stages – and the transition of JHG becoming a rail specialist contractor. So, as this is a lump sum contract which was probably underpriced it would be very difficult not to exceed the budget, this just needs to be as minimal as possible.

The other issues of the last 2 weeks has been focused on defects. The conduit issue on Scalabrini that I mentioned in my last post is a bit of a thorn in my side at the moment. I invited the client down to an ‘unveiling’ of the expansion joint cover plates but without a ribbon cutting ceremony and was largely hoping they were ignorant enough for me to bluff them into accepting the conduits as they are. This seemed to go quite well and they left happier than when they arrived and they certainly didn’t insist on us carrying out any remedial action, what they did ask is if we could submit an RFI which would confirm that everything would be alright. The main problem is I have no way of knowing exactly how the conduits were placed as the subcontractor can’t remember or probably doesn’t care and the engineer for this site when they were put in was on holiday for that week. I do have an idea which I communicated to the designer through an RFI, I sent this to the structural designer though so it came back to me that the designer who designed the services (GHD) would be better placed to answer. In the meantime the JHG design manager sent a response stating that it is crucial this is rectified and that the conduits that seem to be restrained by both sides must be allowed to move at that joint. This is exactly the response you would expect but the cost and time that it will take to rectify will be painful. At the moment I have not formally sent the RFI to GHD who may have more to say on the matter but I need to discuss this with the Construction Manager (he has been on holiday for the past 3 weeks) before we start breaking RC out which will probably result in us further damaging the conduits.

The issue of the Dickson Rd abutment A dowels in the wrong position has also played on my mind for a few weeks. I have been told in the past to only submit RFI’s if it is fully justified as each one cost JHG depending on complexity. After requesting the Design Report and calculation sheets for Dickson Rd which at times was pretty hard to follow – their presentation score on a PET project would receive a consolation mark at best. I couldn’t see an issue with the dowels being set slightly out of position within the abutment width. We still have the correct amount of dowels at the correct  horizontal spacing and the dowels would still be set into the middle third of the diaphragm therefore within the same reinforcement space. I wasn’t prepared to accept my prognosis without some form of official approval though considering the entire structure is propped through the deck/diaphragm interface. TPD (client) and RMS (eventual asset owner) have not noticed the error during their checks but there is a good chance they will once we start reo fixing the deck and I want to have a response ready if/when they do. I ended up phoning the senior bridge designer at SMEC to see what is opinion was and he was under the same impression that it wouldn’t be an issue but unless he received an RFI he wouldn’t be able to crunch a few numbers and give me a formal response. So I submitted the RFI which confirmed that the dowels are alright where they are. This would have probably cost about $10000 to rectify but more importantly doesn’t delay us anymore than we currently have been waiting for the backfill to finish.

Other issues have been regarding concrete strength results. I have been trying to close out the worklot on the piling works for over two months but as it is a 50MPa tremie mix I had to wait for the 56 day strength tests as per sepcification. Boral the concrete provider have stated that it is a 56 day product but the specification from the designer states that 50 MPa should be reached at 28 days. The 28 day results for 8 out of the 10 piles were under the design strength and at 56 days there were just one pile which had one cyclinder at 50MPa and the secind at 48.5MPa. Another RFI to the designer confirmed this as acceptable and can be justified as a sample defect but the results also showed a number of the 56 day results loer than thye 28 day results. To me the practiacalassumption to make would be again that the samples must have been compromised by either poor compaction or pre-test damage to the cyclinders. The RFI response instructed me to confirm that the concrete compressive strength of the mentioned piles was in fact increasing with time and not decreasing. My first thought was the ring them up and ask them if they could suggest a sensible way in which I could achieve this bearing in mind that piles in my limited experience tend to be subterranean and it is even more of a trend to build further bits on top of them – you could say like a foundation! I can only assume they thought we had more cyclinders available to test but this unfortunately is not a university lab with an abundance of concrete to crush for fun and tests cost money. What I have done is shifted the responsibility over to the concrete supplier to justify the results to appease the designer and finally close the work lot. I have had another sub-design strength result in one of the retaining wall bases which have a design strength of 40MPa but the 28 day result is at 37MPa. Current protocols mean that the second cylinder will be retained and crushed at 56 days. This result should yield a +40MPa result.