Large diameter 750mm storm water pipe had complety blown due to blockage by sand caused by storm surge tide damage. The pressure blew out the side of the concrete pipe causing the cliff above to collapse underneath a popular beach playground area. The pipe was non-reinforced hence no access was possible due to potential complete further collapse of the pipe. To make access worse the end of pipe was underwater during high tide.
Excavation of beach sand was initially required to alleviate sand blockage and allow water to escape and enable access. The entire surrounding area needed to be stabilised to enable works. A.R.S. inserted an inflatable bladder into the void, and backfilled the external hole in the ground with high density, hi compression structural expanding foam as the existing non reinforced pipe had no structural integrity and could not be worked on. Traditional methods would have involved pumping concrete into the void to stabilise the site, or digging out and replacing the drain entirely. Due to beach access difficulty this was not viable. Asset Rehab Services were able to hand carry pumps and generators to the site with drums of foam to inject into void. Once the void was stabilised works commenced on the 750mm concrete pipe. The pipe was patched with fibre glass and epoxy resin to repair a 1 to 1.5 sqm hole. Lightweight sheets were used as a mould to hold the shape of the pipe in place against external void packing, then fibre glass patching and resin was used to repair the lining. This was done with the threat of high tide submerging the whole area making the job complex and time cricital.
Once the pipe and surrounding area were rectified other contractors moved in to reinstate landscaping and reopen to the public. The pipe had since endured several extreme storm events with no further damage. Project was completed in 4 day turnaround, on time, on budget, with no variations to quoted amount. Our work is done.