Here is a manual that I used to do the design when I lived in New York State. My design passed.
When I moved to North Carolina they required a design that had 2 fields. The second for backup that was designed and not built. What a pain.
But key in both places were Soil Percolation tests and distances from items such as Wells, streams etc. Also I had to show the math. See Page 103 of the referenced manual.