A. Development by or on behalf of a sewerage undertaker consisting of—
(a)development not above ground level required in connection with the provision, improvement, maintenance or repair of a sewer, outfall pipe, sludge main or associated apparatus;
(b)the provision of a building, plant, machinery or apparatus in, on, over or under land for the purpose of survey or investigation;
(c)the maintenance, improvement or repair of works for measuring the flow in any watercourse or channel;
(d)any works authorised by or required in connection with an order made under section 73 of the Water Resources Act 1991 (power to make ordinary and emergency drought orders);
(e)any other development in, on, over or under their operational land, other than the provision of a building but including the extension or alteration of a building.
A.1 Development is not permitted by Class A(e) if—
(a)it would consist of or include the extension or alteration of a building so that—
(i)its design or external appearance would be materially affected;
(ii)the height of the original building would be exceeded, or the cubic content of the original building would be exceeded, by more than 25%; or
(iii)the floor space of the original building would be exceeded by more than 1,000 square metres;
or
(b)it would consist of the installation or erection of any plant or machinery exceeding 15 metres in height or the height of anything it replaces, whichever is the greater.
A.2 Development is permitted by Class A(b) subject to the condition that, on completion of the survey or investigation, or at the expiration of 6 months from the commencement of the development concerned, whichever is the sooner, all such operations shall cease and all such buildings, plant, machinery and apparatus shall be removed and the land restored as soon as reasonably practicable to its former condition (or to any other condition which may be agreed with the local planning authority).
A.3 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.