NO - you do not cover the septic tank's lid with pavers
How are they going to get the tank serviced?? Huh, how??
The lid on the tank must be accessable.
And yes, you can put things *OVER* the tank, but you can not obstruct access to the lids and or clean-outs.
Some tanks have ratings of handeling a 10,000# load. Note: I said "some tanks", not all tanks. But I would not risk it.