DEWATERING A CONSTRUCTION SITE - Part 1

This case study is typical of a construction company not taking advice from ground water control experts.

As can be observed from the attached photo, the contractor has made some fundamental mistakes

1. After installing I-beam and concrete segmented shoring, they proceded to excavate, without taking into account possible pre-existing ground water control requirements.


2. After excavating to the initial RL seen here, there was no ground water concerns, and the site was dry.


3. After a lengthy period of no further site activity, or mobilisation of the dewatering contractor's scope of works, water inflows started, possibly as a result of dewatering operations being concluded and switched off from surrounding sites.


4. There is no suitably dry platform for the piling contractors to work from, or for the dewatering contractors's drill rig, to install deepwells.


5. The shoring, as can be seen, is not suitable for the conditions, as it cannot provide a sufficiently watertight cutoff from transverse water flow.


6. A dry working platform for the piling contractor and dewatering contractor is unobtainable at this stage


7. The point of discharge is around 2 kilometers away into a stormwater drain.

Observe the mound of backfill material in the left of photo. This is how the contractor has decided on his own methods to retrieve the situation, by trying to backfill the excavation, in defiance of the expert advice provided.

We'll follow this example to its logical conclusion, as a case study on how NOT to excavate a site.