Pressure cleaning in Parramatta

At the 2021 Census, 85.6 per cent of occupied private dwellings in the suburb of Parramatta were flats or apartments. Separate houses were 7.7 per cent. Across New South Wales the figures were 21.7 per cent and 65.6 per cent, so the suburb is close to the state turned upside down.

Widen the view to the whole City of Parramatta local government area and it evens out: 38.9 per cent separate houses and 47.3 per cent flats or apartments, across 92,109 occupied dwellings.

So a Parramatta job is usually one of two different things. In the suburb itself it is common property: entry paths, podium paving, bin rooms, basement ramps and car park floors, booked by a strata manager or a building manager. Further out in the council area it is still the house, the driveway and the gutters.

City of Parramatta Council says stormwater often enters one of its 23,000 drainage pits and is carried underground, and that most of it ends up in the Parramatta River and then Sydney Harbour.

Council names the creeks that feed the river through its area, among them Toongabbie Creek, Darling Mills Creek, Duck River, Vineyard Creek, Subiaco Creek and Clay Cliff Creek. It lists stormwater runoff alongside development and pollution as human activity that affects their health.

Council describes its gross pollutant traps as the last chance to catch litter before it reaches the waterways. A trap built for litter is not built for detergent, oil or fine silt. That is why the wash water from a car park floor or a podium is contained and recovered on the job rather than left for a trap downstream.

The Bureau of Meteorology station at Parramatta North records a mean annual rainfall of 981.6 millimetres. That is more than Penrith Lakes at 756.3 and less than Sydney Observatory Hill at 1211.1.

Humidity follows the same middle path. The yearly average is 73 per cent at 9am and 55 per cent at 3pm at Parramatta North. July nights average a minimum of 6.3 degrees.

On a tower or a podium that shows up as black mould and algae on the shaded faces, the undercroft edges and the paving that the sun never reaches between buildings. Those are soft washed. The car park ramp below them is a hot water job.