By Matthew Baring-Gould, Kingscliff-based drainage plumber. Servicing Tweed Heads for 4 years. 5.0 stars across 173 Google reviews. Licensed NSW 383340C and QLD 15036450. ABN 74 605 392 348.
North Tumbulgum farm property on a hill with heavy surface and groundwater running through the yard. Two days on site. Reshaped the backyard, removed trees, dug a full-length trench from one side of the property behind the house down to a 600mm stormwater pit on the other side. Laid a full French drain in geofabric, 100mm aggie, and 20mm blue metal. Reshaped the land above into a swale so any water that missed the drain still fell toward the pit.
What the customer called us for
Owner called us out for serious drainage issues on a hillside farm at North Tumbulgum. Surface water and groundwater were running down through the yard every rain.
What we found when we got there
On a hillside property on this scale, the water is coming from above and there is no natural sink below. Standard spoon drains and small pits were not going to move the volume. We planned a full French drain the length of the backyard plus a swale re-grade.
Why we did it this way
A proper French drain on a sloping site does two jobs at once. The trench catches groundwater coming through the soil, and the aggie-and-blue-metal fill carries it along to the pit at the low end. The swale reshape on the surface catches anything the drain misses and redirects it the same way. Done properly, it is a permanent fix. Done cheap, it clogs within a year because the fines wash down into the aggie.
What we did on site
- Set up on site with the excavator and earthmoving equipment.
- Removed trees in the drain line and reshaped the backyard.
- Dug a long trench from one side of the property behind the house to a 600mm stormwater pit on the other side.
- Laid geofabric along the full trench floor and walls.
- Laid 100mm aggie pipe along the trench.
- Filled the trench to the top with 20mm blue metal drainage gravel.
- Wrapped the geofabric over the top of the gravel to seal the drain.
- Reshaped the ground above the drain into a swale so surface water also falls toward the pit.
- Worked with the owner’s crew on additional drainage down the back embankment.
The result
Two full days on site. Farm now has a full-length French drain and reshaped surface fall that moves surface and groundwater away from the house pad to a 600mm pit at the low end.
If you have the same issue
If you have a hillside property and every heavy rain brings water through your yard or under your house, a French drain plus a swale re-grade is the right-sized fix. Spoon drains and small pits will not move the volume on anything bigger than a small suburban block. Call Matty on 0447 188 394 or request a quote.
Customer names and addresses have been withheld. Individual results vary. Drain Masters Plumbing is licensed in NSW (383340C) and QLD (15036450).
Frequently asked
Why wrap the geofabric over the top of the gravel too?
The geofabric stops fines (sand, clay, topsoil) migrating into the gravel. If you only line the bottom and sides and leave the top open, surface silt washes in from above within a year and chokes the drainage sock. Wrapping the top keeps the drain working for decades.
Why 20mm blue metal and not recycled gravel?
Recycled gravel brings a layer of concrete dust and fines with it. That dust washes down into the aggie and reduces flow. Blue metal is cleaner, it holds the voids open better, and it is the right spec for a long-lived French drain.
What is a swale?
A shallow, wide, grassed channel on the surface that catches surface water and carries it along a planned path at low speed. On a hillside, a swale running above and parallel to the French drain doubles the system’s capacity and handles the first-flush water.
Browse all our case studies.
Residential, commercial, stormwater, sewer, drainage installs across Tweed Heads, the Northern Rivers, the Gold Coast and Brisbane. See the full collection →
