The original water treatment plant was built in 1974 with a designed output of 55.2 Mld (2,300 m3/h). Asa water treatment plant is the main water treatment facility for the provision of treated water for Ilorin.

During its service life this plant had fallen into disrepair and prior to the rehabilitation works was only capable of providing 40% of design output.

The population of Ilorin has increased and water availability has become a serious issue.

The State Governor of Ilorin invited Biwater to provide a solution for the rehabilitation and expansion of the existing water treatment facility.

Biwater conducted a detailed survey of the existing plant and with its expertise was able to provide a solution that would rehabilitate, expand and also amalgamate the rehabilitation of the existing plant with the proposed new plant that is to be constructed by Biwater.

The contract for the rehabilitation and expansion of Asa Water Treatment was signed on the 11th April 2005. The Contract became effective on the 18th May 2005 with full mobilisation of the site with a contract period of 12 months.

Biwater initially started work on the filter cells as it was identified that some of the filter floors had collapsed. When the filters were drained it was evident that not only had the filter floors collapsed but where the filter floors were intact the media was in such poor condition that the flow was rat holing through the media and effectively no filtration was being achieved.

After a detailed review of the plant Biwater agreed to proceed with the rehabilitation by taking one clarifier plus three filters of line.

Design work has started to remove the redundant infrastructure that will not be required in the new design provided by Biwater. The existing filter floors have been removed and modifications are being carried out. The existing clarifier troughs have been removed including all the stilling plates.

During the site investigation it was found that the existing chemical room basement was becoming flooded. The cause of this was identified as the site outfall which was constructed from earth and had collapsed which had caused the site drainage system to backup and flood the chemical building.

Biwater offered to utilise the existing clarifiers troughs and provide a permanent solution as shown in the photographs above. This solution shows how Biwater working closely with the Client can provide excellent solutions utilising materials that would normally require disposal. It is this ability of Biwater to Engineer solutions on demand that provides the Client an excellent Value Engineered Solution.

Working Closely with the Client Biwater has provided many other solutions that will be beneficial to the Client. These include:-

• The amalgamation of the filter control systems for both the new and existing plants.
• The rationalisation of the chemical preparation and storage facility on the treatment plant.
• The rationalisation of the chlorine facility to provide disinfection for the combine system.