ENVIRONMENT AND ENERGY
These types of urban centres also have large unsewered
areas. Examples include the Accra-Tema conurbation
in Ghana or the conurbation of smaller centres in Metro
Manila. Smaller urban centres typically are towns that
have a small CBD, possibly some small satellites and
radial linear expansion along the major routes. These
smaller urban centres often have very limited sewer
networks, mostly relying on on-site sanitation. They
may be physically close to other centres, but they
have different municipal administrations, and therefore
separated institutional responsibility.
Large villages and small towns are typically quite compact
but differ from urban centres as they have little fringe
expansion. These could also be settlements that have
developed around industrial or commercial activities.
Examples include college campuses, airports and mines.
Rural areas are typically almost entirely served by on-site
systems, without any formal sewer systems. Some urban
runoff management may be practised. The classification
of each centre is dependent on the region. In China, for
example, an urban centre w