Point Piper is only 0.4 square kilometres in size with only eleven streets, yet more draining risk factors
than ten suburbs of its size. A combination of the hundred-year old pipes, aggressive tree roots, steep land
and closeness to harbour water gives a situation, which most plumbers in Sydney have never come across.
Root Intrusion and Mature Fig Trees
The great Port Jackson figs and Moreton Bay figs on Wolseley Road and the harbour foreshore are some
of the features that make Point Piper such a visual sensation. And yet down deep, their root systems
are insatiable. These plants emit high densities of roots that may extend 15 to 20 metres through
the trunk, actively in search of moisture and nutrients. It only takes a crack of hair in an ageing
clay sewer pipe to invite them.
After getting inside, the roots will create thick mats that entrap waste, constrict the pipe and
ultimately block it completely. This is the trend with virtually all Point Piper drain jobs
involving the main sewer lateral, and it is the main cause of the drains in this suburb clogging up
again and again until the damage to the underlying pipes is remedied.
Heritage Pipes Running Under High-end Properties
A good number of the homes in Point Piper are a result of the late 19th century and up to the mid 20
th century. The sewer and stormwater mains under these houses are normally terracotta or
earthenware, which is laid in one-metre segments with cement-mortared connections. The joints have
become loose, the pipes have been broken, the mortar has worn away, after 60 or 100 years in the
ground. All joints are now points of entry of roots and points of weakness where the soil pressure
may cause collapse of the pipe.
The PVC pipes used today do not suffer this weakness, they are installed in longer and fewer joints
and they do not corrode. However, the process of replacing terracotta with PVC involves excavation
or pipe relining, and in Point Piper, where houses have heritage gardens, sandstone retaining walls
and harbour-facing terraces are valued in the hundreds of thousands, the technique of replacement is
critical.
Steeper Terrain and Stormwater Pressure
The topography of the Point Piper is very steep and descends down to the harbour foreshore with a
drop of 30-40 metres in a very short distance between the New South Head Road at the ridge and the
harbour foreshore. Stormwater flows swiftly downhill when it pours heavily. The highest stormwater
load is received by properties at the bottom of the slope, on the Wunulla Road, at the end of
Wentworth Street and the Wolseley Crescent loop. When the stormwater drains are partly not cleared
of silt, leaves or debris, the system fails to handle the peak flow and you experience surcharging,
backflow and flooding of garden areas and lower rooms.
A Figure of Speaking
The total cost of about 20,000 wastewater blockages cleared annually in the Sydney Water network is
about 27 million dollars. The major contributors are fat build-up and other items that are not to be
flushed (wet wipes, sanitary products, cotton buds, etc.). In the residential sector, intrusion by
tree roots prevails in the older pipe system suburbs, and the Eastern Suburbs, and the following
areas of the city, which include: Point Piper, Woollahra, Bellevue Hill, and Rose Bay, are always
among the most affected postcodes.
