Sanitation Systems for Urban Areas

Question 1

Urbanisation in developing countries:

Answer 1

Almost all population growth in the world over the next 40 years is expected to occur in urban areas in developing countries. Most in high density low income areas

Question 2

Effect of urbanisation on sanitation systems:

Answer 2

Because high population densities in urban areas, on-site sanitation systems are not normally feasible.
Low cost, off site systems are more suitable

Question 3

Explain conventional sewerage

Answer 3

Conventional sewerage uses very conservative values for minimum diameters, gradients and depths. Resulting in very high construction costs per household.
Sewerage networks are laid down the centre of the road.

Question 4

Explain simplified sewerage

Answer 4

• With simplified sewerage, these very conservative design codes are relaxed in order to reduce costs. Rigorous hydraulic design principles are maintained.
• Sewerage networks are laid within a housing block (frontyard, backyard or sidewalk)
• PVC pipes used (simple, low cost, reliable junctions with inspection units rather than manholes)
• appropriate for existing unplanned periurban settlements and also for new housing states with more regular layouts
• important that local sewerage authority works closely with the community
• less expensive than on-site sanitation systems

Question 5

What is combined sewerage?

Answer 5

A sewer system that conveys both municipal wastewater and stormwater.
The sewer has to convey the dry-weather wastewater flow and the stormwater flow when it rains

• less expensive than simplified sewerage and separate stormwater drainage.
• design for stormwater flow of a 5-year storm event

Question 6

What are community- managed sanitation blocks?

Answer 6

Sanitation blocks that are designed, built, owned and managed by the communities they serve. For the use of the community members who pay for its upkeep.