Six percent asbestos is soils is an awful lot of asbestos. There is more in some places and less in others. But six percent is a huge amount, compared with the norm.
Just as you wouldn't build a house in a seasonal flood-plain or supermarket over a oil seep, building a school in an area with such a high level of naturally occurring asbestos is not such a great idea. Since that error has been made, it should be corrected by remediation.