My two cents---- It goes back to what is really leaking and where.
Think hard about this one. If you did this, will it really fix the problem. Are you absolutely sure. How much are you willing to stake on it.
If you fail to intersect where that leak is underground by even 6", it will not help. Compare this to the laying down a complete seal/liner, with clay or such. More expensive, but more of a guarantee. Not to be negative here, just be aware of all outcomes and avenues. If it does work, you just saved a bunch of money.
Have you contacted Otto for advice?
