(1) No worker shall enter a caisson unless:(a) he is protected by a steel shoring:i. that is sufficiently resistant;
ii. covering all the depth above the worker who is working therein; and
iii. extending at least 300 mm above ground level;
(b) he uses a boatswain’s chair in accordance with section 3.9.17;
(c) (paragraph revoked);
(d) he is under the constant supervision of another worker for as long as he is in the trench;
(e) he accompanies each load of materials excavated if he cannot take shelter outside the caisson;
(f) any accumulation of water or mud inside the caisson is controlled;
(g) the provisions of Subdivision 3.21 have been complied with.