10 100 40-100 15-55 4.75 90-100 25-40 0-25 2.36 80-100 18-33 0-5 1.18 50-95 - - 0.60 30-75 5-15 - 0.300 10-30 0-7 - 0.150 1-10 - - 0.075 0-3 0-3 0-3 D15 (filter) Piping ratio ---------------- <5 D85 (soil) D15 (filter) Permeability ratio ---------------- >5 D15 (soil) D50 (filter) Mean ---------------- <25 D50 (soil) Where D15 and D50 (filter) are used to designate the size of sieve passing 15 percent and 50 percent respectively size of filter material (i.e. the size of the sieve that allows 15 percent and 50 percent respectively by weight of the filter material to through it). Common Backfill Common backfill materials other than pervious backfill shall be suitable material as defined in Sub-clause 2.3.1 or as directed by the Engineer. Method of Filling Backfilling material shall not be permitted under water unless specifically described in the contract or approved by the Engineer. It shall be placed and compacted in layers in compliance with the requirements of Clause 5.6.1. Any support structures for the excavation shall be withdrawn as the filling proceeds unless described in the contract or ordered by the Engineer to be left in. The backfill shall be placed in by such methods which shall avoid loading the structure in any manner which may affect its stability or overload its underlying foundation material or substructure. The backfill in front of abutments and wing walls shall be placed first to avoid the possibility of forward movement. Precautions shall be taken to prevent any wedge action against upright surfaces, and the slopes bounding the excavation shall be stepped as directed by the Engineer before backfill is placed. The backfill material around box culverts, piers and curtain walls shall be placed simultaneously on both sides of the structure.
10 4.75 2.36 1.18 0.60 0.300 0.150 0.075 100 90-100 80-100 50-95 30-75 10-30 1-10 0-3 40-100 25-40 18-33 - 5-15 0-7 - 0-3 15-55 0-25 0-5 - - - - 0-3 D15 (filter) Piping ratio ---------------- <5 D85 (soil) D15 (filter) Permeability ratio ---------------- >5 D15 (soil) D50 (filter) Mean ---------------- <25 D50 (soil) Where D15 and D50 (filter) are used to designate the size of sieve passing 15 percent and 50 percent respectively size of filter material (i.e. the size of the sieve that allows 15 percent and 50 percent respectively by weight of the filter material to through it). Common Backfill Common backfill materials other than pervious backfill shall be suitable material as defined in Sub-clause 2.3.1 or as directed by the Engineer. Method of Filling Backfilling material shall not be permitted under water unless specifically described in the contract or approved by the Engineer. It shall be placed and compacted in layers in compliance with the requirements of Clause 5.6.1. Any support structures for the excavation shall be withdrawn as the filling proceeds unless described in the contract or ordered by the Engineer to be left in. The backfill shall be placed in by such methods which shall avoid loading the structure in any manner which may affect its stability or overload its underlying foundation material or substructure. The backfill in front of abutments and wing walls shall be placed first to avoid the possibility of forward movement. Precautions shall be taken to prevent any wedge action against upright surfaces, and the slopes bounding the excavation shall be stepped as directed by the Engineer before backfill is placed. The backfill material around box culverts, piers and curtain walls shall be placed simultaneously on both sides of the structure.
Technical-Specification.docx