This is why it is critical to purchase guaranteed septic sand. If the company guarantees it it means that if the sand fails the perc test the company will replace it at no cost. I never did find out if it means they will pay for removal and all redo excavation. The County Guy told me that there were two people that year that failed the perc and had to redo the entire field. One had sand not guaranteed and the other had sand that was. Must have been a nightmare.
Gratefully the sand I got is all good.
There has been some erosion since it has been a year and a half, but the new excavator guy said it isn't too bad. Of course I need more sand to make up for it and also to finish grading the slopes properly.