For the purposes of Class A—
“associated apparatus”, in relation to any sewer, main or pipe, means pumps, machinery or apparatus associated with the relevant sewer, main or pipe;
“sludge main” means a pipe or system of pipes (together with any pumps or other machinery or apparatus associated with it) for the conveyance of the residue of water or sewage treated in a water or sewage treatment works as the case may be, including final effluent or the products of the dewatering or incineration of such residue, or partly for any of those purposes and partly for the conveyance of trade effluent or its residue.