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fermer ce livreA Guide to the Development of on-site Sanitation (WHO; 1992; 246 pages)
Afficher le documentPreface
ouvrir ce répertoire et afficher son contenuPart I. Foundations of sanitary practice
fermer ce répertoirePart II. Detailed design, construction, operation and maintenance
ouvrir ce répertoire et afficher son contenuChapter 5. Technical factors affecting excreta disposal
fermer ce répertoireChapter 6. Operation and maintenance of on-site sanitation
Afficher le documentPit latrines
Afficher le documentSimple pit latrines
Afficher le documentVentilated pit latrines
Afficher le documentVentilated double-pit latrines
Afficher le documentPour-flush latrines
Afficher le documentOffset pour-flush latrines
Afficher le documentDouble-pit offset pour-flush latrines
Afficher le documentRaised pit latrines
Afficher le documentBorehole latrines
Afficher le documentSeptic tanks
Afficher le documentAqua-privies
Afficher le documentDisposal of effluent from septic tanks and aqua-privies
Afficher le documentComposting latrines
Afficher le documentMultiple latrines
Afficher le documentOther latrines
ouvrir ce répertoire et afficher son contenuChapter 7. Components and construction of latrines
ouvrir ce répertoire et afficher son contenuChapter. 8 Design examples
ouvrir ce répertoire et afficher son contenuPart III. Planning and development of on-site sanitation projects
Afficher le documentReferences
Afficher le documentSelected further reading
Afficher le documentGlossary of terms used in this book
Afficher le documentAnnex 1. Reuse of excreta
Afficher le documentAnnex 2. Sullage
Afficher le documentAnnex 3. Reviewers
Afficher le documentSelected WHO publications of related interest
Afficher le documentBack Cover
 

Raised pit latrines

Another way of dealing with the problem of difficult ground conditions close to the surface is to construct raised pit latrines. The pit is excavated as deep as possible, working at the end of the dry season in areas of high groundwater. The lining is extended above ground level until the desired pit volume is achieved.

If the pit extends more than 1.5 m below the ground there will probably be sufficient leaching area below ground for a pit latrine having a full depth of 3.5 m. In such cases, the lining above ground should be sealed by plastering both sides (Fig. 6.17). The minimum below-ground depth depends on the amount of water used in the pit and the permeability of the soil. Where insufficient infiltration area can be obtained below ground level, the raised portion of the pit can be surrounded by a mound of soil. The section of the lining above ground (excluding the top 0.5 m) can be used for infiltration provided the mound is made of permeable soil, well compacted with a stable side slope, and is thick enough to prevent filtrate seeping out of the sides (Fig. 6.18). Earth mounds are not recommended on clay soils as the filtrate is likely to seep out at the base of the mound rather than infiltrate the ground.


Fig. 6.17 Raised pit latrine

 

WHO 91436


Fig. 6.18. Mound latrine

 

WHO 91437

Raised pits can be used in combination with any other type of pit latrine (VIP, pour-flush, double-pit). A common application is where the groundwater level is close to the surface. A slight raising of the pit may prevent splashing of the user or blockage of the pit inlet pipe by floating scum.

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