Local Road Management Manual 172 type of pipe or culvert relative to the water way that is going to flow through it. If the invert elevation appears higher at any point than the stream bed or significantly lower, the Site Inspector should inform the Resident Engineer and check with a level instrument. Drainage construction should start at the downstream going upward to maintain the required invert elevation. c. Excavation i. If soft or unsuitable material is encountered during excavation, it shall be removed to the satisfaction of the Resident Engineer. The Materials Engineer may be referred to should there be any doubt; ii. Before replacement of any excavated soft or unsuitable material, the volume of the excavated material shall be measured and agreed with the Contractor and records signed before submitting to the Resident Engineer; iii. The Site Inspector should find out what material is to be used for backfilling soft areas, and ensure that it is placed and compacted in accordance with the specifications; iv. Any rejected material should be properly disposed in accordance with the Specification requirements; v. Construction of Canals (Ditches) should start in the downstream and must be excavated to such falls as are required to ensure proper discharge of water. The Resident Engineer and Inspector should always check the invert level and width and required side slopes are correct before permitting the Contractor to commence grouting. 2.9 Supervision of Pavement Works Guidance on the supervision of pavements works by the Construction Supervision Team are as follows: a. Subbase Preparation i. Preparation of the sub-base should only be carried out immediately prior to placing of Aggregate Base-course; ii. The compaction of the earthworks will have to be