Product Overview

Summary: This Subsurface Drainage Systems Installation SOP sets out a clear, step-by-step method for planning, installing, and commissioning below‑ground drainage in a safe, compliant, and quality‑controlled way. It helps Australian businesses manage excavation and underground service risks while delivering durable drainage performance that stands up to local soil, rainfall, and regulatory conditions.

Subsurface drainage works sit at the intersection of safety-critical excavation activities and performance-critical infrastructure installation. Poorly planned or inconsistently installed systems can lead to trench collapses, service strikes, flooding, pavement failure, and expensive remediation. This SOP provides a structured, repeatable method for installing subsurface drainage systems on Australian construction, civil, landscaping, and infrastructure projects, from initial site assessment and Dial Before You Dig checks through to backfilling, compaction, and final inspection.

Developed with Australian WHS duties and industry standards in mind, the procedure focuses on controlling high-risk construction activities such as working in and around trenches, operating plant, managing spoil, and handling pipes, geotextiles, and aggregate. At the same time, it embeds quality controls to ensure correct falls, pipe alignment, filter media placement, and protection from contamination and damage. By implementing this SOP, organisations can lift installation quality, standardise training for crews and subcontractors, and demonstrate a defensible, documented approach to managing underground drainage risks and compliance obligations.

Whether you are installing subsoil drains behind retaining walls, under sports fields, alongside pavements, or as part of broader stormwater networks, this SOP helps your team deliver consistent results. It clarifies responsibilities, specifies pre-start checks, and outlines verification steps so that each installation is safe, fit for purpose, and aligned with project specifications and Australian best practice.

Key Benefits

• Reduce excavation and trench-related incidents by embedding clear controls for shoring, access, and exclusion zones.
• Ensure consistent drainage performance through standardised installation methods for pipe gradients, bedding, and filter media.
• Demonstrate WHS and regulatory compliance with documented procedures for underground service checks and plant operations.
• Streamline training and onboarding of new workers and subcontractors with a clear, step-by-step installation framework.
• Minimise rework, defects, and water damage claims by integrating quality inspections and sign‑off points into the installation process.

Who is this for?

• Civil Construction Supervisors
• Site Managers
• Drainage Contractors
• Plumbers and Drainers
• Civil Engineers
• Landscape Construction Supervisors
• WHS Managers and Safety Advisors
• Local Government Works Coordinators
• Irrigation and Turf Installation Contractors
• Project Managers (Civil and Infrastructure)

Hazards Addressed

• Trench collapse and ground instability during excavation
• Contact with underground essential services (electricity, gas, telecommunications, water, sewer)
• Struck-by and crush injuries from mobile plant and machinery
• Manual handling injuries from lifting and placing pipes, geotextiles, and aggregate
• Slips, trips, and falls in and around open trenches and uneven ground
• Exposure to contaminated soil, stagnant water, or biological hazards
• Noise, vibration, and airborne dust from excavation and compaction equipment
• Working in confined or restricted spaces such as pits, inspection chambers, and narrow trenches

Included Sections

• 1.0 Purpose and Scope
• 2.0 Definitions and Abbreviations
• 3.0 Applicable Legislation, Standards and Codes of Practice
• 4.0 Roles and Responsibilities
• 5.0 Pre‑Start Planning and Approvals (Including Dial Before You Dig and Service Locating)
• 6.0 Resources, Plant, Tools and Materials Requirements
• 7.0 Personal Protective Equipment (PPE) Requirements
• 8.0 Hazard Identification and Risk Controls for Excavation and Trenching
• 9.0 Site Preparation, Set‑Out and Survey Requirements
• 10.0 Excavation, Shoring, Benching and Access Procedures
• 11.0 Underground Services Identification, Isolation and Protection
• 12.0 Pipe Bedding, Placement and Alignment Requirements
• 13.0 Installation of Geotextiles, Filter Media and Drainage Accessories
• 14.0 Backfilling, Compaction and Surface Restoration
• 15.0 Working Around Mobile Plant and Traffic Management Controls
• 16.0 Environmental Controls (Sediment, Erosion and Water Management)
• 17.0 Quality Control, Inspection and Testing (Including Levels and Gradients)
• 18.0 Commissioning, Flushing and Verification of Drainage Performance
• 19.0 Documentation, Records and As‑Constructed Information
• 20.0 Training, Competency and Supervision Requirements
• 21.0 Emergency Procedures for Excavation Incidents and Service Strikes
• 22.0 Review, Audit and Continuous Improvement

Legislation & References

• Work Health and Safety Act 2011 (Cth and corresponding state/territory legislation)
• Work Health and Safety Regulations 2011 (and state/territory equivalents), including excavation and construction work provisions
• Safe Work Australia – Excavation Work Code of Practice
• Safe Work Australia – Construction Work Code of Practice
• AS/NZS 3500 Plumbing and drainage series (particularly stormwater and sanitary drainage requirements)
• AS/NZS 2566.2: Buried flexible pipelines – Installation
• AS 3798: Guidelines on earthworks for commercial and residential developments
• AS 2870: Residential slabs and footings (for drainage considerations around structures)
• AS 2159: Piling – Design and installation (for interface with drainage near piled structures, where relevant)
• Dial Before You Dig (Before You Dig Australia) service requirements and utility owner guidelines