The peak rate of run-off and volume run-off criteria can be deemed to be met if the site discharges rainwater directly to a tidal estuary or the sea.
The site run-off must discharge directly into the tidal estuary or the sea. Typically, drainage pipes would only carry run-off from the site and would not need to cross privately owned land outside the boundary of the development before reaching the sea.
A definition of tidal estuary is in the technical manual.