Samalaju is one of the cities in Sarawak, has recently completed a master plan for provision of housing and essential urban services. Phase two of this plan intends to provide sewerage and sewage treatment for a population of 10,000 people. The Samalaju Authorities has recommended to provide a Waste Stabilisation Pond (WSP) system comprising facultative and maturation ponds. This land is geotechnically suitable for ponds, and it gently slopes towards the river (average gradient: 1 in 400). The design data are given as follow: Parameters BOD5 Faecal Coliform Raw Sewage 6.4 300 mg/L 1 x 108 FC/100 ml Effluent (expected) 5.5-9.0