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Table 2

Summary of key physical observations made at sampling sites during field visits

ObservationsSite 1Site 2Site 3Site 4Site 5Site 6
Sampling point Minor and major drain confluence About 100 to 120 m from, and below, Site 1 About 20 to 35 m from and above site 2 Highest elevation of all sites. Confluence of drains serving residential buildings. About 200 to 250 m downstream of Site 4 About 100 to 120 m downstream of Site 5 
Key features/ landmarks Asafo market, bus terminal Main drain in Asafo market Stormwater drain inspection chambers with cover ripped off Business enclave in old Asafo township. Residential area with private kindergarten and pre-school agency. Residential area opposite a basic school (primary and JSS) 
Greywater sources Residential buildings upstream Residential buildings and drains uphill, squatters' greywater Nearby houses and main drains upstream Residential buildings within the drain catchments Residential buildings and other drains upstream Residential buildings and neighbourhood drains 
Vendors/ squatters Vendors/squatters living in area Vendors/squatters living in area Store owners, petty traders, and food vendors nearby No squatters or evidence of them, but some food vendors No food vendors or squatters, or evidence of them No food vendors, petty traders or squatters 
Faecal matter and/or solid waste No faecal matter. Some solid waste – e.g., plastics, food peel, leaves, old clothes, etc – Figure 2(a)  No faecal matter, but some solid waste identified – e.g. food and kitchen debris. No faecal matter either inside or around the spot/chamber. Possibility of solid waste below the silt deposits Only kitchen wastewater from food vendors disposed casually into drains None. No significant silt, either No faecal matter, but drain choked with silt and solid waste. Two people seen pouring soapy water into the drain 
Stench/odour/malodour Minimal Strong, urine-like odour  Presence of malodour Strong stench. Very turbid and dark greywater flowing through No odour, even from the sample(s) Some odour, and there was a complaint of the same in addition to mosquito nuisance. 
Greywater stagnation Minimal. (The concrete drain ends in a runoff created earthen drain) Slow flow, almost stagnant. Informants confirmed that stagnation always occurs during peak flows Chamber silted with stagnant greywater (Figure 2(b)) and wastewater up to 14 cm deep Greywater relatively free flowing without significant stagnation No stagnation, freest flow of all drains visited. Flowing greywater depth was just 5 cm Silted/choked drain caused greywater stagnation. Flow minimal 
Other remarks Solid waste appeared to have been transported and gathered at the concrete drain end New stores have been built on the drain. People seen urinating and pouring kitchen wastewater into drain Traces of recurrent kitchen wastewater discharge seen (kitchen oil, food, etc) by the chamber openings Comparatively small drains – less than 35 cm deep. Greywater free-flowing and relatively clear Least turbid greywater of all sampled, because of stagnation and settling. Water was 25 cm deep because drain was choked 
ObservationsSite 1Site 2Site 3Site 4Site 5Site 6
Sampling point Minor and major drain confluence About 100 to 120 m from, and below, Site 1 About 20 to 35 m from and above site 2 Highest elevation of all sites. Confluence of drains serving residential buildings. About 200 to 250 m downstream of Site 4 About 100 to 120 m downstream of Site 5 
Key features/ landmarks Asafo market, bus terminal Main drain in Asafo market Stormwater drain inspection chambers with cover ripped off Business enclave in old Asafo township. Residential area with private kindergarten and pre-school agency. Residential area opposite a basic school (primary and JSS) 
Greywater sources Residential buildings upstream Residential buildings and drains uphill, squatters' greywater Nearby houses and main drains upstream Residential buildings within the drain catchments Residential buildings and other drains upstream Residential buildings and neighbourhood drains 
Vendors/ squatters Vendors/squatters living in area Vendors/squatters living in area Store owners, petty traders, and food vendors nearby No squatters or evidence of them, but some food vendors No food vendors or squatters, or evidence of them No food vendors, petty traders or squatters 
Faecal matter and/or solid waste No faecal matter. Some solid waste – e.g., plastics, food peel, leaves, old clothes, etc – Figure 2(a)  No faecal matter, but some solid waste identified – e.g. food and kitchen debris. No faecal matter either inside or around the spot/chamber. Possibility of solid waste below the silt deposits Only kitchen wastewater from food vendors disposed casually into drains None. No significant silt, either No faecal matter, but drain choked with silt and solid waste. Two people seen pouring soapy water into the drain 
Stench/odour/malodour Minimal Strong, urine-like odour  Presence of malodour Strong stench. Very turbid and dark greywater flowing through No odour, even from the sample(s) Some odour, and there was a complaint of the same in addition to mosquito nuisance. 
Greywater stagnation Minimal. (The concrete drain ends in a runoff created earthen drain) Slow flow, almost stagnant. Informants confirmed that stagnation always occurs during peak flows Chamber silted with stagnant greywater (Figure 2(b)) and wastewater up to 14 cm deep Greywater relatively free flowing without significant stagnation No stagnation, freest flow of all drains visited. Flowing greywater depth was just 5 cm Silted/choked drain caused greywater stagnation. Flow minimal 
Other remarks Solid waste appeared to have been transported and gathered at the concrete drain end New stores have been built on the drain. People seen urinating and pouring kitchen wastewater into drain Traces of recurrent kitchen wastewater discharge seen (kitchen oil, food, etc) by the chamber openings Comparatively small drains – less than 35 cm deep. Greywater free-flowing and relatively clear Least turbid greywater of all sampled, because of stagnation and settling. Water was 25 cm deep because drain was choked 
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