Sutherland Shire Stormwater & OSD Requirements Explained

The Shire Is Building – and Council Is Watching the Water

Sutherland Shire continues to redevelop steadily, with duplexes and townhouses transforming streets in Caringbah, Miranda, Kirrawee and Sutherland, apartment activity around Cronulla and the Kirrawee brick-pit precinct, and ongoing greenfield and infill growth around Menai, Barden Ridge and Engadine. The 2023 changes to dual occupancy controls in parts of Sydney have kept demand for two-dwelling sites strong across the Shire.

Every one of those projects must satisfy Council’s stormwater controls, and in this LGA they are spelled out in unusual detail.

The Planning Framework: DCP 2015, Chapter 38

The key document is Sutherland Shire Development Control Plan 2015, and specifically Chapter 38 – Stormwater and Groundwater Management. It works alongside Sutherland Shire Local Environmental Plan 2015 and Council’s Environmental Specification – Stormwater Management, which governs the detailed design and construction of drainage and water quality devices.

Chapter 38 covers drainage design, on-site detention, water quality, groundwater and overland flow, and includes principles that catch builders out – for example, stormwater cannot be diverted from one drainage sub-catchment to another, and site levels cannot be changed to redirect runoff to a different sub-catchment.

What Is Typically Required

• On-site detention (OSD): In Sutherland Shire, OSD applies to virtually all forms of development other than single dwelling houses – so duplexes, dual occupancies, townhouses, residential flat buildings and commercial projects should all budget for detention. The OSD restricts discharge to a rate the downstream Council system can accept.
• Stormwater concept plan with the DA: showing the collection network, OSD location and volume, the discharge point and overland flow paths, prepared consistent with Chapter 38 and the Environmental Specification.
• Water quality measures: Pollutant and sediment reduction is an explicit objective; water quality devices must be designed, built and maintained per Council’s stormwater specification, with WSUD measures expected on larger projects.
• Gravity discharge or easement: Rear-falling blocks – common on the ridgelines above the Georges River, Woronora River and Port Hacking – typically need an inter-allotment easement where street discharge is not possible.

Permissible site discharge rates and storage volumes are calculated under Chapter 38’s clauses and should be confirmed current with Council or your engineer at design time.

Local Factors: Georges River and Port Hacking Catchments

The Shire is framed by water: the Georges River to the north and west, the Woronora River through the middle, and Port Hacking to the south, with the Royal National Park beyond. These receiving waters are central to the Shire’s identity, which is why Council pairs detention with genuine water quality requirements.

Topography matters too. Sandstone plateaus fall steeply to the rivers, so many sites combine shallow rock (driving up OSD excavation costs) with steep rear yards draining to bushland. Around Cronulla and low-lying foreshore areas, flat grades and tidal influence can complicate gravity discharge, while dune sands change infiltration behaviour. Menai and Barden Ridge sites often deal with bushland interfaces where uncontrolled discharge causes erosion.

How Builders Should Prepare

• Identify the sub-catchment and legal discharge point before concept design – remember the no-diversion rule.
• Assume OSD on anything bigger than a single dwelling and allow space for it in the site plan early.
• On sandstone sites, price rock excavation for tanks realistically.
• For foreshore or low-lying sites, check flood and overland flow mapping before setting floor levels.
• Use Council’s Environmental Specification details rather than generic ones – it speeds up assessment and certification.

OSD and Stormwater Design in the Sutherland Shire

Contrive Consultants prepares Chapter 38-compliant stormwater and OSD designs for duplexes, townhouses and commercial projects across the Sutherland Shire, from Cronulla to Menai. Review our engineering services or reach out – call +61 497 848 111 or email info@contriveconsultants.com.au.