The following presentation was made to the CRD's Core Area Liquid Waste Management Committee on November 10th 2009 by Dr Shaun Peck.
Dr Peck was addressing a Biosolids report that can be viewed at: http://www.crd.bc.ca/reports/corearealiquidwastem_/2009_/11november10_/index.htm.
The Key Message in this presentation is that the current disposal of Victoria's sewage through two deep sea outfalls is meeting the Provincial and proposed Federal Standard if it is measured in the receiving environment. It is therefore unnecessary to build land based treatment plants that will have adverse effects on the land and global environment.
To-day’s Biosolids report states that the anticipated new Federal standards is for a biological treatment plant capable of producing an effluent quality of 25/25 mg/L biochemical oxygen demand (cBOD5) and total suspended solids (TSS). The plant or plants will need to provide for flows and organic loads up to 2 times average dry weather flow (ADWF).
As you have heard at previous meetings the existing Provincial Municipal Sewage Regulation calls for 45/45 mg/L cBOD5 and TSS.
This raises a question as to how effective the two deep sea outfalls are right now at meeting this requirement in the receiving marine water environment of the Juan de Fuca Strait. I would remind you that the Macaulay outfall is 1.7 KM long, is located at a depth of 65 meters and has a 135 meter long diffuser. The Clover point outfall is similar, 1.1 KM long 65 meters depth and has a 196 meter long diffuser.
With special thanks to CRD Scientific Programs, I have found out to my surprise that the 100 meter edge-of Initial Dilution Zone (IDZ) effluent quality values for the Macaulay Point outfall are 1.27 mg/L for TSS and 0.77 cBOD5 mg/L O2 and for Clover Point outfall are 1.29 and 1.16. Incredibly, these are way below both the Provincial standard of 45 mg/L and anticipated Federal Standard of 25 mg/L!
For our CRD's two outfalls, this means that these Provincial and anticipated Federal treatment standards are being met at a distance considerably less than 100 meters from the diffusers.
As stated by CRD Scientific Programs, “Based on these calculations, we predict environmental concentrations of TSS and cBOD5 at both outfalls to be well below either of the 45mg/L Municipal Sewage Regulation or 25 mg/L National Performance Standards discharge limits at the edge of the Initial Dilution Zone, even under the worst case conditions of highest concentrations and lowest dilutions”.
This illustrates the faulty thinking of regulators who insist that treatment should meet the standard at the plants. The most logical requirement is that the standard should be set, as it is at present, in the receiving environment.
Victoria has a unique marine receiving environment.
The effectiveness of our present system is confirmed by the 2007 marine monitoring report, which states: “The CRD’s scientific studies have found that minor effects resulting from the discharge are observed to a limited area of sediment approximately the size of a football field around each outfall. Oxygen levels remain well above the levels needed to sustain a healthy marine environment.” (I will comment here that two football fields only have a total area of 1.2 hectares – which is much less than even a Haro Woods treatment plant!)
The Marine Monitoring report continues: “There has been little change in seafloor organisms (benthic communities) around the Macaulay Point outfall and studies of horse mussel populations near Clover Point show no harmful effects.”
There are considerable limitations as to what land based sewage treatment plants can reasonably achieve. They do in fact concentrate many substances of concern in a toxic sludge or biosolids (the subject of to-days report) that then has to be disposed of in a way that ends up being more hazardous, less sustainable and incredibly more costly than our present marine-based natural sewage treatment system.
This is emphasized in the following quote from to-day's Biosolids report: “to ensure a successful program concerns about metals, pathogens, emerging contaminants of concern in biosolids products, and air quality, must still be addressed.”
I believe that on November 25th you are going to be asked to approve changes to the Liquid Waste Management Plan that have been requested by the Minister of the Environment.
In view of the findings I have noted I suggest you will show as your first choice the retention and improvement of the existing system, with continued improvements to the CRD’s excellent Source Control Program. The next priority should be the mitigation of the effects on the near shore marine environment of storm drains and sewage overflows to storm drains that occur at two times Average Dry Weather Flow. These surely should be the priorities, to be accomplished and their effect determined before there is any commitment to building land-based plants that will have an adverse effect on the region's land environment, and indeed, on the global environment.
Thank you for your attention,
Dr Shaun Peck,
Public Health Consultant,
Member of Responsible Sewage Treatment Victoria
Member of the Association for Responsible and Environmentally Sustainable Sewage Treatment.