Townhouse Development Preliminary Site Investigation, Sebastopol (Vic)

Project summary

Client / location: Townhouse development site, Sebastopol (near Ballarat), Victoria.

Site area: 4.1 ha.

Scope delivered: Preliminary Site Investigation (PSI) including 30 soil bores to 5 m depth, collection of 15 primary soil samples for contaminant testing, and a subcontracted geotechnical investigation. Reports were delivered to support planning permit requirements.

What we found and why it matters

The site comprised a single brick house, sheds, trees and areas of undeveloped land with a history of agricultural use (including a workshop / machinery repair area). Based on the site history, building ages and materials, the site presented a low risk profile for widespread contamination.

Field sampling identified one localised diesel spill in the workshop area. Laboratory results (NATA‑accredited testing) indicated the impacted soil was limited in extent and suitable for standard remediation or managed‑excavation approaches. Potentially hazardous building materials encountered during demolition (lead paint and asbestos‑containing materials) were flagged for specialist removal and management.

Why we paired geotechnical and environmental drilling

• Combining geotechnical and contamination drilling reduced mobilisation costs and site disruption.
• Shared bore locations allow both engineering and contamination data to be collected from the same soil profile, accelerating interpretation and reporting.
• Faster sample turnaround and consolidated reporting helped meet the planning permit timeframe.

Deliverables, timing and cost (project claims preserved)

• 30 soil bores to 5 m depth and 15 primary contaminant samples.
• Subcontracted geotechnical investigation (partner: Structerre Engineering — as stated by the client project record).
• Environmental and geotechnical reports issued to support planning permit documentation; client reported delivery within two weeks of award and a project cost of just over $10,000.

Practical compliance and approvals notes for developers

• Preliminary Site Investigations (PSIs) are primarily a desktop assessment, but may include limited sampling where warranted. Planning authorities in Victoria refer to Planning Practice Note 30 and will accept PSIs to inform planning decisions for non‑sensitive uses; sensitive uses (schools, childcare, playgrounds) generally require a higher level of assessment under the audit system. Developers should confirm the scope required by the responsible planning authority early in the application process.
• Contaminant screening and interpretation should follow the National Environment Protection (Assessment of Site Contamination) Measure (NEPM) schedules and methodologies when deriving investigation or assessment levels for soils and groundwater.
• Any demolition or refurbishment work must identify and manage asbestos and lead paint risks in accordance with state occupational health and safety requirements. Licensed asbestos removal, pre‑works surveys and clearance procedures are typically required where ACMs may be disturbed.
• Use NATA‑accredited laboratories for contaminant analysis to ensure results are acceptable to planning authorities and auditors.

Risk management and remediation recommendations (summary)

• Localised excavation and disposal or in‑situ management of the small diesel‑impacted area, following appropriate waste classification and disposal routes.
• Pre‑demolition asbestos survey and engagement of licensed removalists for any identified ACMs; a hazardous paint (lead) management plan where lead coatings are present.
• Retain combined geotechnical / environmental datasets for design, earthworks and cut/fill decisions to avoid unexpected costs during construction.

Commercial takeaways for developers and planners

• Early desktop PSI work reduces transaction and approval risk by identifying likely contamination issues before purchase or detailed design.
• Combining geotechnical and environmental investigations can provide measurable cost and time savings — but scope must be tailored so both engineering and contamination objectives are met.
• Clear, defensible reporting (NATA laboratory results, NEPM‑aligned interpretation, and an explicit conceptual site model) smooths planning referrals and reduces the chance of conditions that delay permits.

If you are planning a development on potentially contaminated land

Contact iEnvi for a practical, commercial PSI and combined drilling solution to keep your transaction and permit program on schedule. Call 13000 43684 or visit our contact page to speak with our team.