This is not track related, but is a rule in place with the New England Hilclimb Association.

38. Any driver that has any kind of fluid spill at the top or bottom of the
mountain is responsible to clean the spill up immediately. Containers of oil
absorbing material, a broom and dustpan will be in place at the top and
bottom of the mountain. It is the driver’s responsibility to dispose of the
used material. All cars will have a large trash bag in the car to bring
material down from the top. If spills are not cleaned up the driver will not
be allowed any more runs.

This group uses paved mountain access roads that are generally on public lands. One particular site has had complaints from locals about oil stains on the pavement. I beleive one year the organizers implimented a supplimental rule that required impermiable barriers under all cars while they were parked in the paddock.