11.—(1) In Part 1 of this Schedule–
“background quantity” means, in relation to the release of a substance resulting from an activity, such quantity of that substance as is present in–
water supplied to the site where the activity is carried out;
water abstracted for use in the activity; and
precipitation onto the site on which the activity is carried out;
“Part A activity” means an activity falling within Part A of any Section in Part 1 of this Schedule;
“Part B activity” means an activity falling within Part B of any Section in Part 1 of this Schedule.
(2) For the purposes of the interpretation of Part 1 of this Schedule, and unless the context otherwise requires, a reference to a Section is a reference to the Section so numbered in Part 1 of this Schedule.