Re: 鈥淪torm sewers carry pollution,鈥� editorial, Jan. 19.
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The editorial clearly identifies the public health concern for the many rainwater drains around the coastline of Greater Victoria.
These drains that discharge into the sea close to the beaches carry contaminants 鈥� including sewage from cross-connections, animal waste from roadsides and chemicals (such as petroleum residues from vehicles). The Capital Regional District identified 38 instances of high-rated contaminated drains in 2012 based on the finding of high levels of fecal coliform indicator bacteria.
In addition to the normal rainwater runoff, there are also the designed overflows that occur a few times a year after heavy rainfall, when the unscreened sewage is discharged close to the shoreline from such outfalls as McMicking Point. There is a high potential for human exposure to these drains and overflows and therefore a public health risk of waterborne illness.
This is in complete contrast to Clover and Macaulay points, where the screened sewage is discharged into the marine environment via two deep-sea outfalls that are more than one kilometre from the shore and have 200-metre-long diffusers at the end of them. The outfalls are 60 metres below the ocean surface. By this means, the sewage is treated naturally by the marine environment. A comprehensive study by the CRD concluded that there is no measurable public health risk from the exposure to the sewage plume.
The Capital Regional District鈥檚 Seaterra program plans to construct land-based sewage treatment plants at a (preliminary) cost estimate of $783 million. The decision to go ahead with the plan is supported by the political decisions of three levels of government: municipal (regional), provincial and federal.
The credible judgment of marine scientists, public health officials and engineers that the present discharge of the screened effluent into a unique marine receiving environment, through the two deep-sea outfalls, is highly effective in treating the effluent, has largely been ignored.
No credible scientist has presented evidence to counter the judgment of the University of Victoria marine scientists.
The present practice is described as 鈥渘oxious.鈥� This perception may be understandable. The designed outfalls were based on best engineering practice and have been shown to be highly effective by the comprehensive monitoring. Therefore it seems it is this perception that has driven the demand for land-based sewage treatment plants.
What is now being understood is that land-based sewage treatment plants for Victoria will create more of an environmental issue (when the marine, land and global environments are included) than exists at present.
How will the sludge created by the plants be disposed of? On the land, in the landfill or burned (using much energy)? What will be in the sludge?
There is a great deal of scientific uncertainty about how much of the chemicals of concern and even microplastics will be in the sludge or whether they will be discharged in the residual water through a new outfall at McLoughlin Point.听The remaining diluted sewage water after听treatment still has to be disposed.
There are calls for more complex treatment than the planned secondary treatment to enable reclamation of water. This does not make sense when you consider the abundance of water available at a relatively low cost from the CRD鈥檚 Integrated Water Services.
The regulators are requiring the land-based sewage treatment plants to meet total suspended solids and carbonaceous biochemical oxygen demand levels. This is being achieved within 100 metres of the present deep-sea outfalls. It can also be achieved for the estimated $783 million in the land-based sewage treatment plants.
With all the uncertainties in the plans at this time, the CRD directors could have the wisdom and courage to challenge the federal regulations. Given Victoria鈥檚 unique marine receiving environment, will they seek an exemption to the federal wastewater systems effluent regulations? They would have strong support from marine scientists and public health officials that the present practice of disposing of our screened sewage is the best solution for Greater Victoria.
The present practice is the best solution from an environmental and ecological perspective.
From a public health perspective, fixing the stormwater drains that contaminate the shoreline is a much greater priority than building land-based sewage treatment plants that will have adverse effects on the land and global environment and where there are uncertain benefits for dealing with chemicals of concern.
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Dr. Shaun Peck was the medical health officer for the Capital Regional District from 1989 to 1995.
