specification for subdivision construction of road works and drainage

The aggregate shall be clean and uniformly graded from 2mm to 10mm.
The aggregate shall have a minimum thickness of 150mm all round pipe or strip drain.
The Contractor shall undertake a particle size distribution analysis of the soil prior to selection of the
filter fabric and shall forward the results to the Engineer.
The geofabric filter sock shall be non woven and have the following filtration requirements in relation
to the soil being drained;
D 5OS < 75Φm
EOS < D 85S
EOS < 2.5 x D 50S
generally
EOS > D 15S
EOS < 200 Φm
G > 900
(EOS equivalent open size of fabric)
D13
'AS CONSTRUCTED INFORMATION
The Contractor shall ensure that no part of the work is backfilled or otherwise covered until 'as
constructed= information has been obtained.
The drainage >as constructed= information shall include, but need not be limited to the following:
• type of structure;
• pipe invert levels at all structures;
• grade of pipes and open drains;
• distance between structures;
• pipe size and class;
• invert levels of open drains and dimensions of basins;
• cross-section of open drains;
• change of locations e.g. line alignments tied to properties/lot boundaries.
Such information shall be certified by the Contractor's Surveyor and forwarded to the Shire. Practical
Completion will not be issued until a compliant drainage >as constructed= drawing is provided.
Specification for Subdivision Construction of Road Works and Drainage
Rev. 1 – February 2013
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