Condor Engineering were tasked by Warter council to assess and repair a spillway on a country estate in Warter. The spillway was found to be leaking with heavy rain indicating water finding its way under the spillway into voids. It was determined the best course of action was to rock drill the spillway then followed by pressure grouting to fill all the voids underneath the spillway. 

 

Rock Drilling the Spillway 

The spillway had drill positions along it verified by a geotechnical designer, due to the uncertain nature of the voids under the spillway, the use of heavy plant was not feasible. The drilling was completed using an Atlas Copco CP32 rock drill using a 2m integral drill steel. The drill is powered by a compressor which enables the hammer and rotation while giving effective flush to keep the hole clean of debris. All the holes were drilled before grouting could commence. 

Grouting the Voids under the Spillway 

The entrance and exit of the spillway were first dammed and shuttered to stop any egressing from under or over the spill way. Once securely sealed the grouting station was set up adjacent to the spillway making sure all plant was bunded and laid on Vis queen. Grout was then pumped through the holes made via rock drilling using a tremie pipe. The spillway was observed carefully for any grout egressing either out of the other pre-drilled holes or the entrance and exit of the spillway. 
The grout was pumped until returns were seen from the holes indicating the spillway voids had been filled. The excess grout was cleaned off the spillway and each hole bunged and pointed with hand-mixed cement. The dams and shutters were dismantled and site cleared. 
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