The question of whether an engineer’s report is required after pool removal or fill is one that comes up regularly, particularly for homeowners who plan to build over the filled area, or who are selling the property and want to satisfy a diligent buyer’s due diligence process.
The short answer is: it depends on what you plan to do with the space and what your certifier requires. This guide explains the different scenarios and what level of engineering certification is appropriate for each.
Quick Answer (BLUF)
An engineer’s report is not automatically required for a standard residential pool removal where the filled area will be used as lawn or garden. It is typically required when you want to build a structure (shed, pergola with footings, extension, granny flat) over the filled area. Buyers may ask for engineering confirmation when purchasing a property where a pool has been filled, particularly for higher-value properties. An engineer’s report costs $500-$2,000 depending on scope and provides peace of mind, and evidence, that the fill was done correctly.
When Is an Engineer’s Report Not Required?
For the majority of standard pool removals in the Southern Highlands, a residential pool removed under a CDC, properly backfilled in layers, with a compliance certificate issued by the certifier, an engineer’s report is not a mandatory requirement. The compliance certificate from your accredited certifier confirms the work was done in accordance with the approval, and the certifier’s assessment of the backfill methodology forms part of that confirmation.
For the area to be used as:
- Lawn and garden
- Soft landscaping (planting, garden beds)
- Light structures not requiring footings (a timber garden seat, a lightweight trellis)
- A vegetable garden with raised beds sitting on top of the surface
No engineering report is typically required. The certifier’s compliance certificate, the compaction records from the contractor and the disposal documentation are sufficient.
When Is an Engineer’s Report Recommended or Required?
Scenario 1: Building a Structure Over the Filled Area
This is the most common scenario where an engineer’s report becomes necessary. When you want to build:
- A garden shed with a concrete slab
- A pergola with concrete or steel footings
- A secondary dwelling (granny flat)
- An extension to the main dwelling
- A driveway or hardstand area with significant loading
The building certifier for the new structure will assess the ground conditions and may require a geotechnical or structural engineering assessment of the fill quality before approving the new structure’s footings. This makes sense: standard residential footings assume undisturbed, naturally compacted ground with predictable bearing capacity. A filled pool excavation has different characteristics that must be understood before footing design.
The engineer’s assessment typically involves:
- Review of the pool removal compliance documentation
- Compaction testing (if not already done and certified)
- Assessment of the fill profile and settlement history
- Footing design recommendations for the proposed structure
For full details, see our building over a filled pool guide.
Scenario 2: Selling the Property
When selling a property where a pool has been filled, sophisticated buyers (and their solicitors and building inspectors) may ask for evidence of proper backfill. For most standard residential sales, the CDC/DA approval and compliance certificate are sufficient evidence that the removal was done properly.
However, for:
- Higher-value properties ($2M+) where buyer due diligence is more intensive
- Properties where the filled pool area covers a large portion of the backyard
- Cases where the buyer has concerns about settlement or future building potential
- Properties in Bowral’s heritage market where buyers are often professionally advised
Providing a brief engineering statement (confirming that the fill was properly compacted and is suitable for landscaping or garden use) can smooth the transaction and eliminate buyer uncertainty. This is a relatively low-cost step ($500-$1,000 for a brief engineering letter) that can be very effective in removing a potential objection.
Scenario 3: The Certifier Requires It
Some certifiers, particularly on:
- Larger pools (over 60m²)
- Deep excavations (over 2m)
- Rocky or complex soil profiles (Robertson basalt, Bowral clay)
- Sites in flood-affected areas
May impose a condition on the CDC or DA requiring an engineer’s report or compaction certification. This is listed as a condition of the approval, check your consent document.
Scenario 4: Partial Fill-In (Higher Risk)
For partial fill-ins where the shell remains in place, engineering assessment becomes more important if any future construction is contemplated. The shell’s bearing capacity and long-term stability are unknown without assessment, an engineer’s input is strongly advisable before any structure is placed over a partially-filled shell.
What Does an Engineer’s Report for a Pool Fill Actually Cover?
A typical engineer’s report for a completed pool fill-in includes:
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Site inspection. The engineer visits the site, reviews the documentation from the removal, and observes the current ground condition.
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Compaction verification. If compaction testing data was collected during backfill, the engineer reviews this and confirms it meets the required standard. If no testing was done (or if additional confirmation is needed), the engineer may commission on-site testing at this stage.
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Assessment of the fill profile. The engineer assesses what material was used as fill, how it was placed, and whether any concerns exist about long-term settlement or bearing capacity.
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Conclusion and recommendation. The report states whether the fill is suitable for the intended use (lawn/garden, specific structure, etc.) and any conditions or recommendations.
The report is signed and stamped by a registered structural or geotechnical engineer (check that the engineer holds the relevant RPEQ or CPEng qualification and is registered under the NSW Building Act).
Who Provides an Engineer’s Report?
For pool removal backfill assessments, you need either:
- A geotechnical engineer (who specialises in soil and ground conditions), ideal for assessing fill quality and bearing capacity
- A structural engineer (who can assess footings and structure above ground), most relevant when designing a structure to go over the fill
For a simple “confirm this fill is suitable for garden use” report, a structural engineer with general residential experience can typically provide this. For a more detailed geotechnical assessment including soil testing, a geotechnical specialist is preferable.
Engineering practices based in Bowral, Wollongong or the greater Southern Highlands area typically cover Wingecarribee Shire, confirm geographic coverage when making initial enquiries.
Cost and Timeframe
A brief engineering statement or letter confirming suitability for light use: $500-$800.
A more detailed geotechnical assessment with site testing and a full report: $1,500-$3,000.
A footing design recommendation for a specific structure over the fill: $1,500-$3,500+ depending on complexity.
Allow two to four weeks from initial contact to receiving the report.
FAQs
Does my pool removal contractor’s compaction records replace an engineer’s report?
They’re different documents serving different purposes. Compaction records (typically a printout from a density gauge test or a DCP test result) show that the fill met a specific density standard at the time of placement. An engineer’s report interprets this data in the context of the site, the proposed use and the relevant standards. For simple garden/lawn use, compaction records alone are often sufficient. For building purposes, an engineer interprets the records and takes professional responsibility for the conclusion.
My buyer’s solicitor asked for an “engineer’s certificate for the pool fill.” What does this mean?
They’re asking for a statement from a registered engineer confirming that the backfill was done properly and is suitable for the property’s intended use. This is a reasonable request, particularly on higher-value properties. Provide the CDC/DA approval, compliance certificate and compaction records to the engineer, they’ll review these and provide the certificate. This process typically takes one to two weeks.
How long after pool removal should I wait before commissioning an engineer’s report?
For an immediate assessment of compaction quality (to inform a current building decision or sale), an engineer can assess immediately after removal. For an assessment of settlement behaviour (relevant for understanding long-term building suitability), waiting six to twelve months allows for one seasonal cycle of wet-dry and potentially frost action. Discuss your timing with the engineer based on your purpose.
Does the engineer’s report have a liability if the ground settles unexpectedly?
Registered engineers carry professional indemnity insurance and take professional responsibility for the conclusions in their reports. If an engineer certifies a fill as suitable for a specific purpose and that conclusion is later proven incorrect, the engineer has professional liability. This is precisely why engineering certification has value, it’s not just a form, it’s a professional opinion backed by insurance.