(Credit 4.1 states: 'Design the lot such that at least 70% of the buildable land; not including area under roof, is permeable or designed to capture water runoff for infiltration on site.' )
Is there a minimum percentage of the total site area that must be considered a "buildable" land area for the permeable lot?

Also, what is the definition of a 'steep' slope for permanent erosion control?

Thank you.