Drainage FAQ — Port Stephens

The price follows the work: how much digging there is, how much pipe, and what has to come up and go back down. Relining a damaged stormwater pipe is usually priced per metre plus a set-up charge, so a short section costs more per metre than a long one, and digging it up and replacing it is usually dearer again. In Port Stephens, work near Hunter Water pipes can add a cost of its own: plans submitted to Hunter Water for assessment attract a plan stamping fee, and Hunter Water publishes its fees on its website. Get two or three quotes, and ask each contractor to put a camera down the drain before pricing it.

It depends on the job, so check with Port Stephens Council before any work that changes where stormwater goes. In Council's mapped stormwater control areas, the DCP 2025 lets small-scale residential work, such as a house, a dual occupancy or alterations and additions, use a Deemed to Comply solution or a stormwater management plan. Hunter Water's pipes are a separate matter. As a general guide, Hunter Water says buildings and structures should be kept at least 1.5 m from its assets. Pressure sewer assets have to stay accessible and can't be built over, and work close to or over Hunter Water pipes may need a Build Over Asset Application or a Development Assessment Application.

Usually one of five things. Ground falling toward the house instead of away. An old ag drain that has silted up. A blocked or crushed stormwater pipe, so pits fill and spill. Sand over clay, or a high water table near the bay, so rain sinks a short way then spreads sideways. Or low ground near Tilligerry Creek where the outlet backs up. Council's 2017 Anna Bay and Tilligerry Creek Flood Study notes that in a big flood the creek, Fullerton Cove and the Hunter River can meet, and all three move with the tide, so a low outlet can't drain at high tide. We tell them apart by walking the block after rain to see where water comes from and stops, a test pit, and a camera down the pipe for silt, roots or a break. Bureau of Meteorology records for Williamtown RAAF put mean annual rainfall at 1134.4 mm over 78 years and March the wettest month at 127.2 mm, so March is when a wet yard shows worst and when to have us look.

Stormwater drainage carries rain off roofs, paving and the yard surface to the street system or another legal point of discharge. Subsoil (or ag) drainage sits underground, usually as slotted pipe in a geotextile sock and gravel, and intercepts groundwater before it reaches footings or gets under a slab. Infiltration means soaking stormwater into the ground on your own lot. In its mapped stormwater control areas, Port Stephens Council's DCP 2025 treats sandy soils (Types A and B) and clay soils (Types C and D) differently, and where infiltration is shown to be unsuitable for a site, the clay-soil detention rules apply. A wet yard can need more than one of these looked at.

Under clause B3.3 of Port Stephens DCP 2025, a rear-sloping lot with no existing drainage easement or inter-allotment drainage must provide a legal point of discharge. Failing that, an easement through adjoining private land may be required. A charged roof-water line to the street may be considered if it's shown to work and neighbours aren't adversely affected in storms up to and including the 1% AEP (a 1% chance each year). Under clause B3.4, a lot draining straight to a public reserve or waterbody, with no public drainage connection, doesn't need on-site detention or infiltration if stormwater up to that storm is managed on site without offsite scour, erosion or downstream nuisance.

It can. Water left against footings softens the ground under them, and on reactive clay the soil swells when wet and shrinks when dry, so the footing moves with it. The signs are cracks that open and close with the seasons, doors that stick after rain, and a step in the floor. Drainage comes first. If the footing is still level, regrading the ground and an ag drain along the wet side are usually enough to stop it moving. Where a footing has already dropped, underpinning is the structural fix: the footing is re-supported on firmer ground below the wet zone, and lifted where it can be. The drainage still has to be sorted, or the ground around the new support and under the rest of the footing keeps getting wet and moving, and the cracks come back. We handle the drainage side. Bureau of Meteorology records for Williamtown RAAF average more than 111 mm in each month from February to June, so that is the stretch to check where water sits against the walls.