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IADT
IADT

Description:

The project involved building a new sewerage holding tank and pumping station. All the pipework, manholesand pumping station had to be built below the water table. When the new infrastructure was built the existingsewer pipework in the golf course and neighbouring houses was connected to the new system. An overground pressure line was installed out to the Clontarf road main sewer.

All of the new infrastructure had to be fitted in running sand where the water table was less then 1m belowthe surface.

For the new pumping station, 16no RSJ were driven around the perimeter. Outside of this well points weresunk @ 900mm centres, 2m below the invert level of the tank. These were hooked up to a suction headerpipe. Two large suction pumps were running 24/7 with 1 additional pump on standby. Within 72hrs the waterflow had reduce, indicating that it was safe to start digging.

Digging inside the RSJ`s to a depth of 1.2m, a line of shuttering panels were then inserted between the RSJ`sand welded in place. We continued in this sequence until we got to our reduced level. There was no watergetting past the well points, even though wewere working approximately 8m below the watertable.

The manholes were prefabricated in concrete onthe ground. To install the manholes and pipework,well pointed were sunk, similar to themain chamber. The areas were given at least24hrs to dewater and then dug like a conventionaltrench. The well points kept the water back and the sand stool like stiff bolder clay.

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