Ysgol Emrys Ap Iwan headmaster Matt Wildsmith has cordoned off areas of the school site in Abergele, Conwy, to protect pupils and issued a warning over vehicles speeding down a road.
Peter Davidson, 68, and Janet Devereux, 58, want to bring tourists to the Conwy Valley, but the half-built development has been opposed by neighbours - and rejected by Conwy councillors.
Conwy in north Wales has hosted a bakery of some kind on its site in Castle Street for hundreds of years, according to its current owners - but could soon have competition.
Supply issues first became a problem for residents in the Conwy county on Wednesday, after a major water main was reported damaged at the Bryn Cowlyd Water Treatment Works in Dolgarrog.
Around 40,000 households in north Wales face having no water as five schools have been forced to temporarily shut their doors after a pipe burst at a treatment plant.