Holdfast Training Services Trial Blog

As I mentioned in the last blog, the SCL works for the shaft are now complete. As a result the base plug, some 230m3 of concrete was poured to ensure there was no effect from the uplift heave. The plug was left to cure and then the 3 x depressurisation wells were grouted to seal them.

The next phase was to start installing the waterproof sheeting. However this could not be put in place untill the protective layer was installed. The protective layer is essentially a sheet of thin white foam. The foam stops the steel fibers that are in the SCL from penetrating the waterproof sheeting.

The protective layer is nailed into place, allowing a large washer to be installed allowing the waterproof sheeting to be welded. This ensures that the waterproof layer is never punctured by nails.

As you can see from the photos the waterproof sheeting comes in rolls of approx 2m. As a result the sheeting needs to be heat welded to each other to ensure a watertight fit. To make certain that the waterproof sheeting has been welded together correctly the joints are pressure tested. The overlap between each sheet is filled with air and the pressure is taken for 10 mins. If the pressure decreases the seal is not 100% perfect, as a result the weld is redone.

The final result is that the base is looking like a giant swimming pool.

The next phase is to install the huge reinforcement cage into the base and then pour a further 450m3 of concrete. It seems like a huge overdesign but the designers have insisted on the second pour. Once the second pour has been completed we will be at the Adit level. This will be the point that the waterproofing for the shaft sides will be installed, shortly followed by the Insitu lining.

On a different point, Gemma Quickenden (Sub Agent) has now left the project. This has allowed me to take over the running of the Compensation Events. With the completion of the SCL works the SCL  CE’s are being dealt with. I arranged the first meeting with Barhale yesterday to talk through all their CE’s. I had hoped we could agree on the majority of the 26 CE’s however we have agreed upon 5. This has been the most enjoyable part of the secondement so far, as it allows you to debate/argue with those individuals you have been wanting to shout at for the past 6 months.