Most retaining walls that fail don’t fail because the wall was too thin. They fail because water built up behind them. If you’re on a sloping block in Greater Bendigo, good drainage is the part of the job you can’t see but can’t do without. Bendigo Retaining Walls connects you with a local, registered and insured builder who builds drainage in from the start.
Call 0485 557 649 to talk about your slope.
Bendigo’s ground, in brief
A 2023 bushfire assessment prepared for the City of Greater Bendigo describes land to the north of the city as generally flat, becoming increasingly undulating and hilly to the south, south-west and south-east, with steeper hills and valleys around the city centre. So a block in Spring Gully or the western rises of Golden Square behaves very differently from a flat lot in Huntly.
Underneath, Bendigo’s bedrock is mostly old sandstone, siltstone and mudstone, folded into ridges. The City’s Golden Square Heritage Study notes that the creeks and gullies hold alluvial deposits of sand, clay and gravel. In practice, builders can strike anything from clay to broken rock when they dig, and a soil test or geotechnical report is the only way to know for sure on your block.
Cut, fill or both?
- Cut. Digging into the slope to create a flat area, with a wall holding back the higher ground. Creates spoil that has to be moved or removed.
- Fill. Building up the low side and holding the fill with a wall. Fill must be placed and compacted properly, and can affect your neighbour.
- Cut and fill. A bit of both, which is common for house pads, sheds and driveways on new estates.
- Tiered walls. Two lower walls with a garden bed between them instead of one tall wall. Ask your builder or building surveyor whether tiers are treated as separate walls, as it depends on the spacing and loads.
Fill and excavation that could affect the stability of your land or a neighbour’s can trigger a building permit even for a low wall. See our permit guide.
Why water matters
When soil behind a wall gets saturated, the water adds a lot of extra pressure on the wall (hydrostatic pressure). Clay soils hold water and drain slowly, and many clays swell and shrink as they wet and dry. Without drainage, that pressure can push a wall over, bow the sleepers, or wash soil out through the joints.
What good drainage looks like
- Ag pipe (slotted drainage pipe) along the base of the wall, laid with a fall to an outlet.
- Clean drainage gravel behind the wall, often 20 mm crushed rock, so water can move freely down to the pipe.
- Filter fabric (geotextile) between the gravel and the soil so fine clay doesn’t clog the gravel.
- A proper outlet. Water must go to a suitable stormwater connection or other approved point, not onto your neighbour’s land.
- Surface drainage. Shaping the ground or adding a spoon drain above the wall so runoff doesn’t pour over the top.
- Weep holes in solid walls such as Besser block and mortared stone.
Flood-prone areas
Parts of northern Bendigo, including Epsom and Huntly, flooded in October 2022 and January 2024. The City says the local landform, the network of creeks and changes from historical mining all contribute to flooding there. If your property is in a flood overlay, check with the City of Greater Bendigo before adding fill or walls, as a planning permit may be needed and works shouldn’t block overland flow. See our Epsom and Huntly pages.
Old mining ground
Greater Bendigo was mined from the 1850s. EPA Victoria advises anyone landscaping or excavating in historical mining regions to check the site’s history first, and to stop and assess if they uncover suspected mining sands or waste. Old shafts and mullock (waste rock) also turn up. Tell your builder if you know your block has a mining history.
Looking after your wall
- Keep the outlet clear and check it after heavy rain.
- Don’t let garden beds or turf build up over the top of the wall.
- Plant large trees well away from the wall.
- Watch for leaning, bowing, cracks, wet patches or soil washing through.
For costs, see the retaining wall cost guide. To talk about your sloping block, Call 0485 557 649.
Bendigo Retaining Walls is a referral service, not a building company. We pass your enquiry to one independent, local retaining wall builder, who inspects the site, quotes and carries out the work under their own registration and insurance. Builder registration details are provided with your quote.