9.—(1) This paragraph applies for the purpose of determining whether an activity carried out in a stationary technical unit falls within a description in Part A which refers to capacity, other than design holding capacity.
(2) Where a person carries out several activities falling within the same description in Part A in different parts of the same stationary technical unit or in different stationary technical units on the same site, the capacities of each part or unit, as the case may be, shall be added together and the total capacity shall be attributed to each part or unit for the purpose of determining whether the activity carried out in each part or unit falls within a description in Part A.
(3) For the purpose of sub-paragraph (2), no account shall be taken of capacity when determining whether activities fall within the same description.
(4) Where an activity falls within a description in Part A by virtue of this paragraph it shall not be taken to be an activity falling within a description in Part B.