The MSABI team lead by Sanitation Manager Naomi Ng’endo undertook an inspection of the latrine system at Idete Primary School. This was our first school latrine system which was built mid 2010. We have used this pilot project as a template for replication and improvement for new designs. On this trip we inspected the wastewater treatment system. This is where we put emphasis on our design and construction quality. The septic tank is the expensive component of our construction – consisting of a solid bottom slab and foundation and fully water proofed tank and slab ceiling. I was very impressed with the internal inspection of the tank. The tank is working as designed and the anaerobic digestion of the sludge appears to be excellent. The baffle wall and overflow to the irrigation system is working well. The bananas we planted are struggling, likely due to the poor soil – the area is more suited to cassava. It’s a fine balance between a low cost structure and durability. The total cost of the treatment system and 8x latrine stalls was TZS 5 million – around $3500 only. This is very cheap and less than half of typical government/NGO budgets which work on >$1000/latrine stall. For our next designs we will increase the cost by around $500-1000 to improve the robustness of the latrine stall construction – namely a concrete ring beam around the superstructure, pre-mould squat plates and hand washing tank.
External view of the septic tank system
Internal view of the septic tank. The system seems to be developing a good bacteriological colony suitable for sludge digestion.