Hi Eric
Assuming a Clay Core earthfilled dam.
You must avoid overtopping so a temporary spillway / tunnel must be constructed to divert the river during construction.
This has to be in place before anything else.
Then in the first dry season when the river is at its lowest point:
You can start the pumped grout shield to seal the fissures in river bed.
Next the key tench to take the base of the clay core.
Now you start the infill with a combination of puddled clay and earth embankments.
It is essential that you have enough haul units to deliver the material to raise the level high enough to be above the anticipated level at the next rainy season. Consider using conveyor belts supplemented with trucks.
Once you have passed the first rainy season then you should be able start hauling again.
Put the wet seasons on the calendar as non work days - it will be unlikely that the clay and the earth will be compactable in wet conditions.
The volume to be hauled reduces as the dam rises so a varialble average mass haul will determine the number of trucks required each month.
The turbine hall can be constructed concurrently with the dam - together with the inlet drop.
At the top of the inside face of the dam there is a layer of sharp rocks to break up any wave action - this is the rip rap.
There will be a conctrete spill way on the downstream side to allow for future floods and to keep the lake level constant - this has to be designed to avoid cavitation.
Construction of the spillway can proceed upwards following the dam fill.
When the dam has reached the top level then the diversion tunnel is blocked the lake will start to fill and water drop into the turbine hall and power will start to generate.
But not before the O'head transmission lines are ready to take it away.
I hope that helps
Best regards
Mike Testro