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Background 

Since the review of water resources of the Lobam-Busung Peninsula was carried out in 1993 to set up the industrial site, a wide range of options have been investigated. Abstraction from shallow groundwater and the Lake Java sandpits provided the first supply of 2 Mld.

To meet increased demand on the industrial estate, water supply was increased to 6.5 Mld, from 1995 to 1997, by doubling the groundwater production, and increasing the storage characteristics of Lake Java. Due to multiple-source blending difficulties, groundwater from the well-field in 1999 was pumped directly into Lake Java, so that pre-mixed ground and surface water could be delivered, by the Lake Java pumping station, to the treatment plant on the industrial estate.

 Process tests and increase in water demand

The WRA project looked at options to increase water supply to 7 Mld in the short-term, and then to 12 and 18 Mld in the medium-term. The project reviewed and costed all the identified schemes, including the combination of water supply with excavation for landfill materials. A strategy was developed for managing drawdown in lake water level during drought conditions. Water chemistry was reviewed and process tests performed on site, to optimize water treatment parameters, and investigate requirements for treatment of highly discoloured peat swamp water.

The favoured option focused on the construction of a small dam on Sg Sasah, and work activities included hydrographic and hydrometric surveys, with logistic support of the client, and development of catchment models using HYSIM. The simulated flow data were used to establish yield of the scheme variants, using reservoir behaviour simulation.