(a) Site Selection: List distances from drinking water sources (should be uphill
and 30 m away from water sources and 2 m above the rainy season
water table) and community dwellings (should be 6 m and 50 m from
dwellings for avoidance of disease transmission but ease of use). Note,
more space is necessary in coarse or fissured ground – find local
hydrogeological expertise [12].
(b) Latrine Demand
(i) Latrine Unit Demand. State the unit demand of the system (i.e., X liter
per person per day) and references (preferably multiple sources, like
literature, on-site percolation tests, and current latrine pit rate use).
(ii) Time to Fill Pit. State design time to fill pit, which is usually between
1 and 5 years (i.e., designed to fill in 3 years).
(c) Pit Size. Use a conservative estimate of pit use per person, and give pit size
given the unit demand and number of people to use pit for the given time to
fill pit.
(d) Pit Emptying. State how the pit will be emptied or closed with the slab
moved, and provide references to current practices near or in the
community.
(e) Geotechnical Analysis. Give the soil bearing pressure used for the design,
and state any geological considerations that are considered in the design
with references.
(f) Structural Calculations. Use calculations to show that the pit and superstructure can resist lateral water loads, any anticipated roof loading, and
lateral loads from earthquakes or wind. Give calculations for the live and
dead loads experienced by the superstructure.
(g) Pit Lining. Include the pit lining material and provide calculations and/or
justification that the lining can handle foreseen seismic and rain events.
(h) Hydraulic Analysis. Calculate pipe sizes and slopes for all connections from
appurtenances to the pit and urine diversion system if present.
(i) Latrine Closure. Explain how the latrine pit will be closed when finished to
minimize pathogen destruction, including emptying method if necessary.
(j) Ventilation. Provide calculations to show that foul smells will not remain in
superstructure.
(k) Composting Latrines Only:
(i) C:N Ratio. State carbon to nitrogen ratio and reference (i.e., 30:1).
(ii) Temperature. Provide heap temperature and reference (40–50
C).
(iii) Ventilation. Calculate ventilation of water vapor and CO2 out and
O2 in.
(iv) Moisture. Provide moisture content evaluation (45–70%, Eawag
Tech Compendium [13]).
(v) Urine Diversion. Explain methodology to divert and use urine, if
applicable.
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J. Knight et al.
and 30 m away from water sources and 2 m above the rainy season
water table) and community dwellings (should be 6 m and 50 m from
dwellings for avoidance of disease transmission but ease of use). Note,
more space is necessary in coarse or fissured ground – find local
hydrogeological expertise [12].
(b) Latrine Demand
(i) Latrine Unit Demand. State the unit demand of the system (i.e., X liter
per person per day) and references (preferably multiple sources, like
literature, on-site percolation tests, and current latrine pit rate use).
(ii) Time to Fill Pit. State design time to fill pit, which is usually between
1 and 5 years (i.e., designed to fill in 3 years).
(c) Pit Size. Use a conservative estimate of pit use per person, and give pit size
given the unit demand and number of people to use pit for the given time to
fill pit.
(d) Pit Emptying. State how the pit will be emptied or closed with the slab
moved, and provide references to current practices near or in the
community.
(e) Geotechnical Analysis. Give the soil bearing pressure used for the design,
and state any geological considerations that are considered in the design
with references.
(f) Structural Calculations. Use calculations to show that the pit and superstructure can resist lateral water loads, any anticipated roof loading, and
lateral loads from earthquakes or wind. Give calculations for the live and
dead loads experienced by the superstructure.
(g) Pit Lining. Include the pit lining material and provide calculations and/or
justification that the lining can handle foreseen seismic and rain events.
(h) Hydraulic Analysis. Calculate pipe sizes and slopes for all connections from
appurtenances to the pit and urine diversion system if present.
(i) Latrine Closure. Explain how the latrine pit will be closed when finished to
minimize pathogen destruction, including emptying method if necessary.
(j) Ventilation. Provide calculations to show that foul smells will not remain in
superstructure.
(k) Composting Latrines Only:
(i) C:N Ratio. State carbon to nitrogen ratio and reference (i.e., 30:1).
(ii) Temperature. Provide heap temperature and reference (40–50
C).
(iii) Ventilation. Calculate ventilation of water vapor and CO2 out and
O2 in.
(iv) Moisture. Provide moisture content evaluation (45–70%, Eawag
Tech Compendium [13]).
(v) Urine Diversion. Explain methodology to divert and use urine, if
applicable.
44
J. Knight et al.