Not every pool removal needs a retaining wall, but many do, particularly where the pool was built into a slope, cut into a terrace, or sits close to a boundary where the ground levels differ. The need for a retaining wall is determined by the height differential of the surrounding ground and the stability of the backfill, not just the depth of the original pool. Your pool removal contractor should flag this during site assessment, but understanding the basics helps you ask the right questions and budget appropriately.
The short answer: if your pool was cut into a sloping block, built against a terrace, or surrounded by soil at different levels on each side, expect some form of retaining structure to be needed once the pool is removed.
Why a Retaining Wall May Be Needed
When a pool is excavated out of a hillside or terrace, the surrounding soil is held in place partly by the pool walls. Once the pool structure is removed and the void is backfilled, that lateral soil support disappears. The backfill material (crushed concrete, gravel, and topsoil) compacts differently from the original ground, and without proper containment, surrounding soil can move, slump, or erode over time.
A retaining wall serves two purposes after pool removal:
- Structural containment, holds the backfill in place and prevents lateral soil movement from adjacent higher ground
- Grade management, creates a clean, stable change in level that allows the backyard to function properly for landscaping, paving, or future building works
In flat backyards where the pool was fully recessed into level ground, a retaining wall may not be needed at all, the backfill is contained by the flat surrounds. But in the Hunter region, where many properties are on undulating blocks, particularly in suburbs like Charlestown, Redhead, Belmont, Glendale, and areas around the Maitland hills, retaining is a common post-removal requirement.
How to Tell If Your Property Will Need One
During site inspection, your contractor should assess:
- Ground level differential: Is there a height difference greater than 300-600mm on any side of the pool?
- Soil type: Clay-heavy soils (common in Lake Macquarie) are more prone to lateral movement than sandy or rocky soils
- Proximity to boundary: If the pool is close to a boundary where a neighbour’s yard is at a higher level, retaining is almost certainly required
- Slope gradient: Blocks with a gradient steeper than 1:5 (20%) typically need retaining structures
- Planned use of the area: If you plan to build a slab, deck, or granny flat over the area, retaining walls may be required as part of that structure
A geotechnical assessment, see our guide on geotechnical reports after pool fill-in, can formally identify retaining requirements and specify what type of wall is needed.
Types of Retaining Walls Used After Pool Removal
| Wall Type | Best For | Cost Range (Hunter Region) | Engineering Required? |
|---|---|---|---|
| Sleeper retaining wall (hardwood) | Low retaining (<600mm), garden borders | $300 to $800/lm | No (under 600mm) |
| Timber pole wall | Low to medium retaining | $400 to $900/lm | Maybe (600mm, 1m) |
| Concrete block (Besser/masonry) | Medium retaining, load-bearing | $600 to $1,200/lm | Yes (over 1m) |
| Segmental concrete block (e.g., Keystone) | Sloping blocks, flexible heights | $500 to $1,000/lm | Yes (over 1m) |
| Reinforced concrete (engineer-designed) | High retaining, near structures | $1,200 to $2,500/lm | Yes (always) |
| Rock gabion cage | Natural-look, large height changes | $800 to $1,800/lm | Yes |
For most standard pool removals in the Hunter region, a sleeper wall or segmental block wall is sufficient. Engineered reinforced concrete is typically only required where the height differential exceeds 1.2 metres or where the wall is adjacent to a structure (house, garage, neighbouring building).
The Engineering and Council Requirements
Under NSW building regulations, any retaining wall over 600mm in height requires a building approval, this is a development application or complying development certificate (CDC) depending on your council and the specific circumstances. In Newcastle City Council, Lake Macquarie City Council, and Maitland City Council areas, this threshold applies consistently.
Retaining walls over 1m in height typically also require engineering certification, a structural engineer must specify the wall design, footing depth, drainage provisions, and materials. This is not a formality; inadequate retaining walls can fail catastrophically, particularly after wet weather.
The Hunter region gets significant rainfall events, and Lake Macquarie and Maitland areas can experience fast-draining hillside runoff that puts hydrostatic pressure on retaining structures. Proper drainage (slotted ag pipe, scoria backfill, weep holes) behind the retaining wall is essential and should be specified by the engineer.
Integrating Retaining Wall Work into Pool Removal
The most cost-effective time to build a retaining wall is during or immediately after pool removal, while the excavator is on site and the area is exposed. Waiting until after the job is complete means bringing equipment back and potentially disturbing fresh backfill.
A well-coordinated pool removal project will typically:
- Remove the pool shell and excavate as needed
- Install drainage and ag pipe as part of the backfill process
- Construct any required retaining structures while the machinery is accessible
- Complete the backfill and compaction in layers, referencing the retaining wall as the boundary
- Achieve compaction certification (see compaction certificate after pool fill)
Ask your contractor upfront whether retaining wall construction is included in their scope or whether it’s a separate engagement. Not all pool removal companies build retaining walls, you may need to engage a separate landscape construction company if your contractor doesn’t offer it.
Retaining Wall Costs: What to Budget
For a typical Hunter region pool removal where a retaining wall is required:
- Small garden sleeper wall (under 600mm, 5-8 linear metres): $2,500 to $6,000 including materials and installation
- Medium retaining wall (600mm, 1m, 8-15 linear metres): $7,000 to $15,000 including engineering
- Large or engineered wall (over 1m, 15m+ linear metres): $20,000 to $50,000+ depending on wall type and engineering requirements
These costs are in addition to the pool removal itself. If you’re budgeting for a complete project, factor in retaining from the start rather than treating it as an afterthought.
Impact on Future Building Over the Pool Area
If you plan to build over the filled pool area, a slab, granny flat, garage, or deck, the retaining wall becomes even more important. A properly engineered retaining wall provides a defined boundary for the building envelope and helps specify what load the backfilled area can carry.
See our guide on building over a filled-in pool for what engineering and certifications are needed before construction starts. The pool excavation and backfill service covers what’s involved in preparing the site for future construction.
What Happens to the Pool Fence Near a Retaining Wall?
If your pool fence runs along or incorporates the retaining structure, its removal adds a layer of complexity. The pool fence posts may be embedded in or on top of a retaining structure, removing them or the fence needs to be done carefully to avoid destabilising the wall. This is another reason to plan the entire scope, pool, fence, and retaining wall, as a coordinated project.
Erosion Risk During Construction
During the period between pool removal and retaining wall construction, exposed soil on sloping blocks is vulnerable to erosion, particularly in wet weather. NSW regulations require erosion and sediment controls to be maintained until the site is stabilised. See our erosion and sediment control guide for what this involves.
Frequently Asked Questions
Do I definitely need a retaining wall if my pool is on a flat block? Not necessarily. On a flat block where the pool was fully recessed and the surrounding ground is level, well-compacted backfill may be all that’s needed. Your contractor will assess this during site inspection.
Who designs and approves the retaining wall? For walls over 600mm, you’ll need a licensed structural or civil engineer to design the wall and certify the design. For walls over 1m, you’ll also need a building approval from your local council (Newcastle, Lake Macquarie, or Maitland).
Can my pool removal contractor build the retaining wall? Some can, some can’t. Check whether your contractor is a licensed builder (not just a demolition contractor), as retaining wall construction above 600mm may require a builder’s licence depending on the work category. Ask for evidence of the relevant licence.
How long does a retaining wall take to build after pool removal? A straightforward sleeper or block retaining wall can be built in one to three days. An engineered concrete wall with drainage provisions can take a week or more, plus the lead time for engineering design and council approval if required.
Will a retaining wall after pool removal affect my property value? Properly constructed retaining walls are a positive feature, they indicate a well-managed site and allow the backyard to be used effectively. Poorly built walls (unstable, no drainage) are a liability. Commission engineering for anything over 600mm to protect your investment.
Need a pool removal that includes a full assessment of retaining and site stability? Contact Hunter Pool Removals for a free site inspection and quote, we cover Newcastle, Lake Macquarie, Maitland, and the Hunter Valley.