Greenfield subdivision design — 124-lot Logan release.

Project overview

A SE Queensland developer engaged ASTCAD for the full civil engineering documentation of a 124-lot residential subdivision within Logan City Council. The 13.4 ha site required staged release across three phases, with retention basin design, road reticulation and full lot servicing.

The challenge

The site sloped 4-7% across an undulating ridge, requiring careful balance between cut/fill volumes and floor level requirements. SEQ Code stormwater detention requirements applied, plus the site fed into an existing council sewer pump station near capacity. Council required certified design and construction documentation before earthworks approval.

Our approach

• Road design to Logan City planning scheme with 18 m corridor widths
• Stormwater management with on-site detention to SEQ Code
• Sewer reticulation design with capacity check on receiving pump station
• Lot grading optimised for cut/fill balance — net earthworks under 8,000 m³
• Staged construction plan supporting three release phases

Deliverables

• Civil engineering drawings (124 sheets across roads, drainage, services)
• Hydraulic and hydrological reports per SEQ Code
• Sewer capacity assessment and council approval letter
• Staged construction methodology
• QSurv-ready plans for lot creation

Outcome

Stage 1 of the subdivision was civil-complete within 7 months of design sign-off. Council inspections passed first time with no remediation works required. Stages 2 and 3 are under construction with the same documentation set.

How we approach greenfield subdivision design

Greenfield subdivision design is a yield optimisation problem wrapped in a compliance framework. We start with the constraints — overland flow paths, sewer depths, road hierarchy connections and the planning scheme’s lot mix requirements — then iterate the layout with the town planner until lot yield, earthworks cost and drainage all work together. Road and drainage design follows the council’s development manual, sewer and water reticulation is designed to the service authority’s standards, and every lot is checked for a compliant building envelope, driveway grade and service connection before the plan is locked.

Subdivision documentation and approvals

Deliverables run from the development application drawings through to operational works documentation: road plans and sections, stormwater and water quality design, sewer and water reticulation, earthworks and retaining plans, and services coordination. We respond to council referral comments as part of the engagement and carry the design through construction certification, so the developer has one accountable engineering line from lodgement to sealed plan.

If you hold or are acquiring englobo land, an early feasibility layout with servicing assessment is the cheapest risk control available — it prices the civil works realistically before contracts go unconditional. We deliver these quickly and carry the work forward into full design when the project proceeds.

Timing matters as much as design quality in subdivision work: the difference between a plan sealed this financial year and next is often just how quickly referral responses turn around. We structure our documentation to anticipate the standard referral comments for the local authority — because after enough projects in a council area, the comments are predictable — and respond within days rather than resubmission cycles. Developers working to settlement deadlines or staged sales programs feel this difference directly in their finance costs.

Recent regulatory shifts also reward developers who document early: infrastructure charges, water quality offsets and flood mapping updates all move, and a design lodged this quarter is assessed under this quarter’s rules. We keep current with the local frameworks so your lodgement lands cleanly the first time.