December 16, 2025
Dual Occupancy Stormwater: Duplex Design in Western Sydney
What a duplex stormwater package really involves in Western Sydney — OSD, easements, clay soils, subdivision traps and what certifiers check at…
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Updates from Contrive Consultants.
July 8, 2025
OSD for Knock-Down Rebuilds & Tight Sydney Infill Lots
Fitting on-site detention on tight Sydney lots — tank placement, existing impervious credits and design tricks for knock-down rebuilds.
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February 13, 2024
ARR 2019 in Practice: How New Rainfall Data Changes OSD Design
How ARR 2019's ensemble temporal patterns, 2016 IFDs and pre-burst rainfall change OSD and drainage design for NSW builders, developers and certifiers.
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November 14, 2023
OSD + Rainwater Tanks: How Combined Systems Work in NSW
Combined detention/retention tanks can satisfy OSD and rainwater reuse in one structure. How they work and what NSW councils look for.
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