8th October 2009

It was agreed to drive the first of the access ramp halfway support piles as far as possible to see if we could drive to the depth required for the pontoon piles. This pile was quite a good one to use as a test pile as it is identical to the pontoon piles, complete with the steel box section splice, however the box section doesn't need to be driven completely into the mud, just low enough to get below the access ramp. After half an hour of driving the pile has essentially stopped moving...the splice is sitting with its bottom section just above the mud, instead of the top of the splice just below the mud! The splice has gone just 4metres into the river bed instead of the required 5metres. I wished we'd cut a metre off the pile before we started! We then started thinking of what to do next as the options are limited to hiring a larger hammer, or boring a hole for the pile to be driven into. It is decided that before we do either of those options we will test load the pile and see if it will withstand its design load of a side pull of 1 tonne, plus a safety margin. Don't forget that the floating pontoons place no vertical load on their piles, only a side load and though the pile has reached a set and won't go in any further, it may not withstand the required side load.