Where an excavation, ditch, pond watercourse, made-up ground, or similar condition adjoins or is on or adjacent to the subsoil on which any building is to be erected, and, in the opinion of the local authority, is likely to impair the stability of the building-

a) the foundation of such building shall be constructed at such depth that the effect of such condition is entirely obviated; or

b) the excavation or cavity shall be adequately backfilled and consolidated with approved material, or

c) such other works shall be undertaken as are adequate for the purpose of securing the stability of the building to be erected.