DRAINAGE EXCAVATION — GOLD COAST & BRISBANE

Drainage problems are the slow-burning damage of any Gold Coast property. Surface water that ponds against a slab corner will rot the framing in 3–5 years. Subsurface water that wicks into a retaining wall footing will fail the wall inside a decade. Roof water that dumps onto an old soakwell that can't keep up will undermine your driveway. We dig drainage trenches and pits that fix the problem properly, not just bandaid it.

Stormwater connection trenching is the most common drainage job. Roof downpipe collected to a 100mm or 150mm PVC line, fall maintained at 1:100 minimum, run to the council kerb stormwater connection or to a soakwell. We trench, lay the line to fall, bed in sand, and backfill in 100mm lifts. Plumber connects up the downpipes and the kerb tap.

Ag-line drainage is the workhorse for subsurface water. Slotted 100mm pipe in geo-fabric sock, laid in a 200mm wide × 400mm deep trench in coarse drainage rock (10–20mm), wrapped in geo-fabric, backfilled. Used behind retaining walls, around slab edges, on the high side of cuts, and across boggy paddock zones. Done right it works for 30+ years.

Pit and pipe networks tie multiple drainage runs together. We dig the trenches, set the pits to level, lay the pipe with the right falls, and grade the surrounds for connection. Common on acreage, larger residential blocks, and any property with multiple downpipes that need to combine before reaching the kerb.

Soakwells and absorption trenches handle stormwater on blocks that can't connect to council. We dig the soakwell pit (typically 1.2m × 1.2m × 1.5m or larger), wrap with geo-fabric, surround with drainage rock, and connect inlet pipes. Absorption trenches are the linear version — a long trench full of drainage rock that spreads the water sideways into the soil profile.

Cut-off drains protect any sloping block from upslope water. A 300mm wide × 400mm deep ag-line trench installed across the high side of a house pad or driveway, intercepting upslope surface water and routing it sideways to a stormwater connection or absorption trench. Mandatory on most hinterland blocks (Tallai, Mudgeeraba, Bonogin, Currumbin Valley) and the single most cost-effective drainage investment you can make.

Tight access drainage work is also routine for us. Backyard drainage trenches behind houses, side-path drainage retrofits, garden bed drainage, paving sub-drainage. Our 1.7T fits a 900mm gate and our 1.0T sub-hire fits 750mm — most backyard drainage problems we can solve without taking out a fence.