Supply all required materials, excavate to perform widening and deepening existing main drainage along Eastern side perimeter wall, excavation will be in all types of soils (even rock layers or existing foundation concrete) including compaction for the base of excavation, to make a rectangular open drain channel dimension of approximately 1.2m and 1.5m deep. The rates include trimming of sides to correct slopes and cart away excavated materials. Depth to invert n.e 2.0m.provide for lining of the base and sides, supply, lay and joints precast concrete invert block drain of dimensions 450x600x150mm and precast paving slabs of dimensions 600x600x75mm as directed by the engineer (EXPIRED)