FINISH TO FINISH RELATION

Hi Arun

Your dewatering activity is best set up as a summary bar or hammock over the excavation - backfill tasks.

You will need to add some time for installing and removing the dewatering systems so it is not a true SS - FF relationship.

As a rule you should avoid all SS and FF links and work with FS only.

Best regards

Mike Testro

Sorry Mike 

Friends please help 

Arun,

There are many dewatering systems;

1. can be from the very rudimentary like my favorite on small jobs, use a 55 gal drum, make many holes and burry the drum at the lowest point in your excavation. The drum surrounded by gravel and an electrical pump inside it.
2. can be a simple well point with suction pumps on a single stage.
3. can be a sophisticated well point system in stages with non suction pumps when water table is too high for suction pumps be practical.

Mikes suggestion I believe on target as it can be adapted to many situations. The following screen illustrates the concept of using the hammock activity that in your software might be called something different, the approach can be similar. Note setup activity is of the ALAP type, use this type with caution, preferably limit such activity types to a single successor.

I added resource loading and use of shifts as to illustrate why sometimes a single activity is not enough. You will notice setup and removal are activities with fixed duration and working on a regular shift while dewatering is a 24/7 activity that requires work during 3 shifts. The dewatering activity might be delayed by pumps delivery and it will delay your excavation, also removal of dewatering can be delayed, need not to be continuous.

Best regards,

Rafael