I see that you have not gotten any answers yet.
I am not local enough to give you specific info, but perhaps I can help you find out. Call your local township or boro where the property is located and ask for the SEO (Sewerage enforcement officer.) That is the person assigned to test and verify the potential of a perk on a particular site and location. I have always found them to be very helpful. The secretaries at some township offices are very knowledgealble, and in other cases are NOT, although they are trying to be helpful. Make sure you verify any info that you get from them.
Typically the cost for the test is very moderate-- probably only a few hundred, but be aware that NOTall land will perc!! However there are other options for alternate systems, and the SEO will know that.
Hope that helps.