SMALL-BORE SEWERSMain learnings on a study madein Africa, Asia and Latin America

Cécile Denormandie, AFDDenis Désille, pS-EauJean-Marie Ily, pS-EauChristophe Le Jallé, pS-Eau

Aims of our study

• Identifying strengths and weaknesses, regarding technical, financial and management issues

• When small-bore sewers are relevant?

• Which recommandations for implementation?

© WSP

What are small-bore sewers?

© Reed

Small-bore sewers are widelydisseminated all over the world

But most of them face difficulties

• Technical issues: gradients are too low, wastewater leakage, poor-quality concrete, etc.

• Financial issues: recurring operating costs are under-estimated, too few connexions , low collection rate of the sanitation fee , etc.

• Management issues: O&M skills are missing, operator is not clearly identified

• Institutional issues: no contract, no monitoring, no control

Main Learnings

Main learning #1Feasability is very restrictive

• Money is needed (SBS is more expensive than onsite sanitation)

• Other public services must be very efficient (solid wastes, rainwater, access to drinking water, land property…)

• A location for the treatment plant is fundamental (except if the SBS is connected to a conventional sewer)

• Users demand for SBS has to be confirmed

Main learning #2Building SBS is NOT the main issue

There used to be mistakes in design and implementation :

- slope is the main mistake !

- Pipes level higher than householdsanitation facilities level

- Waterproofness

- Etc.

BUT the main issue is management…

Main learning #3Small sewer does not mean small management

• Sewer operator skills required:– Responsive technical management

(4 levels of O&M)– Financial management capacities

(tariff, invoices, balance of the service, etc.)

– Marketing skills (to rise up numberof connexions)

– Social abilities (SBS is very sensitive to bad users practices)

• A monitoring system, with control and sanctions

© EAWAG-SANDEC

Conclusions

• Is SBS a proper solution to provide sustainable sanitation services in pro-poor contexts?

• Prefer management delegated to professional authorities / companies instead of CBOs

• Attention and resources should be dedicated to support the post-project period (1 to 3 first years of service management)

Coming soon, guidebook« When choosing

and how to implementand manage small-bore sewers »

© Hydroconseil

Thank You!