Maybe not bad advise. Read the following tech notes and see how they may apply:http://www.polyphaser.com/technical_notes.aspx
There may be a better way and that is to use metal conduit from tower to shack. Bonded at both ends to the ground. This conduit will become part of the ground and act as a Faraday Shield to the cables it contains.
Documents in the above tech notes will discuss the issue of magnetic coupling from a near strike (could be the tower or a nearby tree) into the cables. You also need to look at the inductance the buried cables will have and use it to calculate the entire circuit. What you need to do is place a conductor that offers a lower inductance than presented by the coax. This way it will take most of the current presented by the lightening. Depending upon the numbers and size of coax used, that conductor may be something larger than 1/0 copper wire!
Proper grounding is not a set of hard and fast rule as each situation is unique. Best to ask someone who knows what they are doing rather than invite trouble into the house.
I recommend all users of antennas be familiar with the notes in the above link. PolyPhaser is basically giving away hundreds of dollars worth of grounding and lightening protection training for free.