I agree with packing the pond bottom. It's cheap insurance. Ask the boss how much it would cost to come back and pack it if it filled with water and the water leaks out

Personally? I would pack every square foot of the pond that will be under water.

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3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).