North Head Sewage Plant Still Pollutes, Still Smells.
The Independent Pricing and Regulatory Tribunal (IPART) recently approved only one of the two additional digesters sought by Sydney Water for the North Head biosolids amplification project. As a consequence Sydney Water is currently reviewing the options that will flow from operating the plant with less equipment than they deemed necessary.
The need for the second digester was supported by the New South Wales Environmental Protection Authority (EPA).
The EPA advised IPART that current load limits and concentration limits for some sewage treatment plants were derived many years ago. North Head licence load and concentration limits were set many years ago.
The quantity and composition of the material pumped into the ocean at North Head
The current EPA licence load limits the discharge into the ocean at North Head is 35,011 tonnes for solids and 5570 tonnes for oil and grease also the licence sets concentration limits for discharging solids, oil and grease into the ocean.
Licence Assessable Pollutants Load limits in kilograms
BOD (Coastal Water) (Biological Oxygen demand) 35010800 Cadmium (Coastal Water) 283
Chromium (Coastal Water) 3011
Copper (Coastal Water) 37583
Lead (Coastal Water) 3568
Mercury (Coastal Water) 60
Nitrogen (total) Coastal Water 7957000
Oil and Grease (Coastal Water) 5569900 Pesticides and PCBs (Coastal Water) 370
Phosphorus (total) (Coastal Water) 1909680
Selenium (Coastal Water) 2387
Total Suspended Solids (Coastal Water) 35010800
Zinc (Coastal Water) 51066
Under the EPA licence millions of dollars are paid annually by Sydney Water to the State Government for the right to discharge these pollutants from the Plant into the marine environment.
The impact of the cleaning process of the digesters
Sydney Water has operated the treatment plant with three digesters since September 2007 and each of these digesters needs to be cleaned and refurbished and this process takes a digester off-line for seven months. One digester was cleaned in 2014, a second one was cleaned in 2015 and cleaning of the third is due to be completed in December 2016.
Sydney Water’s digesters maintenance information indicates that a temporary increase in odours may occur during the cleaning process and recently, there have been days in succession when strong odours reached the two parking areas for viewing the harbour on the North Head Scenic Driveway.
In addition, the number of biosolids truck movements increase only in the first month when a digester is cleaned. Biosolids trucks still emit biosolids and deodoriser odours when moving through the streets of Manly.
Micro plastic particles entering the ocean
Treated effluent from the wastewater treatment plants is a pathway for micro plastic particles to enter the ocean.
This worldwide problem of plastic in the marine environment has made operators of wastewater treatment plants throughout the world seek solutions to the problem of micro plastics in effluent discharged to the marine environment.
We hope that the New South Wales government has decided that the problem should be looked at for North Head treatment plant.
We have not lost sight of the fact that the solution sought by Sydney Water for the North Head treatment plant has not been announced. We await a decision that will lead to a better outcome for the community and the environment.
Candy Bingham, Deputy Mayor, Northern Beaches Council. Background in marketing, public relations & community engagement. Author of five business books. Former Lady Mayoress of Sydney. Aka Candy Tymson.