Bill of quantities for a latrine block, desludging plan and latrine monitoring

Slab concrete: 4 × 1.2 × 1.2 × 0.08 = 0.4608 m³; with 10% wastage: 0.507 m³. Cement 0.507 × 350 = 177.4 kg; sand 0.507 × 0.45 = 0.228 m³; gravel 0.507 × 0.85 = 0.431 m³.

Pit walls: side at the centreline 0.9 + 0.11 = 1.01 m; perimeter 4.04 m; area per pit 4.04 × 1.5 = 6.06 m²; 4 pits: 24.24 m². Bricks: 24.24 × 55 = 1,333.2, with 5%: 1,399.9, i.e. 1,400 bricks.

Mortar: 24.24 × 0.03 = 0.727 m³; cement 0.727 × 300 = 218.2 kg; sand 0.727 × 1.1 = 0.800 m³.

Reinforcement: 9 bars × 2 directions × 4 slabs = 72 pieces of 1.1 m (79.2 m). A 12 m bar gives 10 pieces of 1.1 m (1 m offcut): 72 / 10 = 7.2, i.e. 8 bars (and not 79.2 / 12 = 6.6, i.e. 7, which ignores offcuts).

To be added in a complete estimate: superstructure, doors and locks, lighting, handwashing station, labour and transport.

Filling: useful volume 0.9 × 0.9 × 1.0 = 0.81 m³; input 20 × 0.08 = 1.6 m³ per year; time 0.81 / 1.6 = 0.506 years, i.e. about 6.1 months. Desludging is scheduled earlier, for example every 5 months, to keep a margin.

Sector: 150 / 6.1 = about 25 cubicles per month; volume 150 × 20 × 0.08 / 12 = 20 m³ per month (25 × 0.81 = 20.3 m³). Trips: 20.3 / 2 = 10.1, i.e. 11 trips; at 3 per day: 4 truck days per month.

Monsoon: in May, desludge all pits in inaccessible areas that are more than 50% full (they would reach the threshold during the closure); plan supervised manual desludging (hand pump, sealed drums, protective equipment) and accessible transfer points; build replacement pits or additional cubicles in the worst-affected areas; monitor pit levels every week; include these measures in the contract with the service provider.

Results: functional cubicles 85%; locks on women's cubicles 55%; lighting 40%; signposted separation 70%; handwashing 50%; pits more than 75% full: 22.5%.

Severity: the most serious issue is the safety of women and girls: 45% of women's cubicles without a lock, 60% of blocks without lighting, women no longer using the latrines at night. This is a risk of gender-based violence and a failure of access. Next: 9 pits almost full, which will soon make those cubicles unusable, in addition to the 6 cubicles already out of service; handwashing missing in half of the blocks (risk of diarrhoea); no management of sanitary materials.

Plan: (1) this week: repair or fit the 9 missing locks, desludge the 9 pits, repair the 6 cubicles; (2) within 2 weeks: solar lighting for the 6 unlit blocks, signage for the 3 blocks, handwashing stations with a water and soap resupply system entrusted to the committees; (3) lidded bins emptied regularly in women's cubicles, with adolescent girls consulted on menstrual hygiene management; (4) consultation of women on the location of future blocks; (5) monthly monitoring with these indicators and sharing with the protection team.

• Setting out: location agreed with the community and with women; distance from water points (at least 30 m as a general rule, more in a high water table); no flood-prone area; access for desludging; separate cubicles for women and men.
• Pit: internal dimensions (0.9 × 0.9 × 1.5 m); brick quality (firing, no broken bricks); correct mortar mix; joints; plumb walls.
• Slab: formwork, spacing of reinforcement (15 cm), concrete cover, concrete mix, 8 cm thickness, drop hole and footrests, slope towards the hole; moist curing for at least 7 days before placing.
• Superstructure: stability, roof, ventilation, door with inside lock, lighting, handwashing station, bin in women's cubicles, ramp or accessible cubicle for people with disabilities.
• Handover: joint inspection with a signed report, list of reservations, photos, quantities completed compared with the estimate; payment only after the reservations have been cleared.

I refuse: discharging faecal sludge into a channel contaminates water used downstream and can cause an outbreak of diarrhoea, or even cholera, in a very densely populated camp. It is also contrary to the sector's sanitation rules and the authorities' permits. I acknowledge the block leader's real problem and propose: (1) manual desludging by a trained and equipped team, with storage in sealed drums until an accessible transfer point; (2) closing and sealing off the full cubicles, and temporarily installing additional latrines; (3) on-site treatment of the sludge with lime as a last resort, according to the sector's instructions; (4) informing residents. I inform my manager and the sector's sanitation technical working group.