There was no nearby school, but the effluent ponds from a local Cheese factory used to provide a similar experience if you passed near them and the wind was in the right direction.
Aerating the ponds was apparently the solution to that. They started using electricity-driven paddle wheels to periodically beat the hell out of the liquid, and there has been no unpleasant odours since. (Maybe they've since switched to a more energy-efficient method of aerating.)
Cheers,
Rob