6″ tee 2,900 sand = 1,000 (refer to this table) thrust per 100 PSI/bearing load of soil= the required area of the thrust block per 100 PSI of water pressure, what size is needed?

6″ tee 2,900 sand = 1,000 (refer to this table) thrust per 100 PSI/bearing load of soil= the required area of the thrust block per 100 PSI of water pressure, what size is needed?