Earthing a Telecommunications Tower

Hi All

I am busy with the earthing design of a 60m telecommunication tower. I am using copper for the entire earthing. The area is 19x13m. the tower has 3 foot foundations of 3.8x3.8. I have assumed earth resistance of 2ohm and soil resistivity of 100ohm/m. The ps i have assumed as 3000ohm/m. I have assumed the fault current to be 45kA and duration of fault of 1sec. The time duration for estep and etouch as 0.5sec. I would like to calculate the tolerable step,touch voltage and ground rise potential. I also need to calculate the size of the earth mat and the earth rod size. I am getting bogged down with the formulae regarding the sizing of earth mat since there is tons of formulae for earthing. I calculate a value for estep and etouch but what is the permissible values? once I have sized the earth mat my doubt is how do i design the grid pattern once sizing it and also need to know whether the cross sectional area of each joint(grid pattern) is sufficiently sized to withstand the current.

Please could some one help me regarding this.