What types of alternate septic systems (if any) you can employ when land will not perc depends upon the Septic System Laws for your state.
Some states allow only a gravity system and an elevated sand mound system and when perc testing will not allow either one, you have land that will make a nice farm pasture but will never be buildable.
Hope this isn't your case.
The bottom line is you need to contact your community's Sewage Code Enforcement office to get all information you can about what alternatives you may have to this negative basic perc test.