Heritage Cases

Johannesburg Water SOC Ltd proposes to develop and operate a new concrete reservoir located in Lenasia South within the City of Johannesburg Metropolitan Municipality, Gauteng Province. The proposed concrete reservoir site is situated approximately 35km south west of the Johannesburg central business district where it is adjacent to the north western boundary of an existing Lenasia HL reservoir. The proposed reservoir will have a capacity of 15 mega litres and the associated development footprint will be approximately one (1) hectare in extent. This includes the concrete reservoir and the surrounding servitude yard. The proposed development entailed evaluating three (3) different options for the floor slab of the new Lenasia HL reservoir. The first option is to construct a conventional floor with joints in it at 6.0m centre to centre grid. The second alternative is to construct the reinforced slab without joints (of which is the preferred option). The third alternative is to construct a post tensioned floor slab also without joints. Proposed Floor Slab Option 1: Conventional Floor Slab with Joints - This option is for the conventional 250mm thick reinforced concrete floor slab with joints at 6.0m centre to centre forming a grid. The floor slopes at minimum 0.5% to a central drainage channel as described above for maintenance purposes. Floor joints consist of water stop, joint filler, sealant as well as a bandage. The in situ concrete channel also has joints matching slab joints at 6.0m centre to centre. Floor Slab Option 2: Jointless RC Floor Slab - (Preferred) - Constructing jointless floors are in line with international trends. Joints for this option will be limited to the trench perimeter only. This will limit the leakage and the maintenance needed on the floor slab. The floor will have a thickness of 250mm and will be heavily reinforced and designed to BS 8007 for 0.2mm crack width. No joints are specified for the channel. Floor Slab Option 3: Post Tensioned Floor Slab - The floor slab will have a thickness of 200mm and will have a band of reinforced concrete 2.0m wide along its perimeter and 4.0m wide along the center, as indicated in the drawing. The remainder concrete inside this band shall be unreinforced. The floor will be post tensioned to 1.0MPa residual compression to BS 8007 using a bonded post tensioning system. No Go Option - The „do nothing alternative‟ is the option of not constructing the reservoir on site. This alternative would result in no additional environmental impacts on the site or its surrounding area. This option would result in the additional capacity as needed at the Lenasia HL reservoir in order to supply adequate water to Lenasia South ext.1 and 4, Migson Manor (Lenasia South ext.7), Zakariyya Park and additional areas of Vlakfontein Proper, Finetown, Hospital Hill and Lehae not to be realised. Ultimately this would have a negative result of not delivering a vital service delivery of water provision. This option is thus undesired.