Exclusion of Athletic Fields?

Hi, We have a schools project with a large athletic field on site. Because this large area is within the site boundary, we are required to protect/restore 50% of the site excluding the building footprint, as this square footage was calculated to be the larger of the two. My question is, can we exclude the square footage of the athletic field when determining how much area we need to protect? It seems that we should be able to exclude it, as the field must be turf and realistically could not be converted to native grass. Thanks!