I would like to draw the Eastside Select Committee’s attention to the fact that Dockside Green is not a model for Eastside sewage treatment.
In recent years a grassroots plan has arisen to move towards a distributed, tertiary sewage treatment system within the Capital Regional District ( CRD ), along the lines of the Dockside Green tertiary sewage treatment facility in Victoria West. Victoria’s Mayor Lisa Helps is herself a big booster of the Dockside Green model, going so far as to use Dockside Green as the backdrop for the recent announcement of the longlist of potential Eastside sewage treatment sites. Leaving aside for a moment both the cost and environmental soundness of such a plan, it is instructive to scrutinise it in terms of its feasibility, especially with respect to its scalability. In other words, does it really hold water?
The first thing is, Dockside Green is a standalone sewage treatment model. In other words, the sewage treatment system was built into the Dockside Green development at the time it was designed and built. Unfortunately, this kind of model does not work with the built environment within the CRD, with its decades old, patchwork network of pipes, conveyors, pump stations and outfall pipes. So, Dockside Green only works for other Dockside Green-type developments, or in areas or communities that are not yet hooked up to the current sewage network; and such areas are by and large restricted to the Westside part of the CRD- not the Eastside.
The other knock against Dockside Green is that while it may work on a small scale, it is unsuitable for treating sewage on a region-wide scale. To understand why this is so, let’s crunch some numbers. The region says it needs the capacity to treat 108,000 m³ per day of sewage within the Core Area. That just happens to be 285 times the current licensed, maximum daily capacity of 380 m³ for the Dockside Green plant.[1] In other words, if Dockside Green is used as the model for sewage treatment in Greater Victoria, then at least 285 such plants would be required to treat all of the CRD's sewage. How realistic is that?
One decentralised sewage treatment model which seems to have gained traction within CRD circles, and which has been endorsed by none other than Nobel laureate and BC Green Party MLA Andrew Weaver, calls for something in the range of 15 neighbourhood tertiary treatment plants, built around existing pump stations such as the one at Currie Road in Oak Bay. Bear in mind that the Currie Road pumping station has a current treatment capacity of 13,500 m³ of sewage per day. This means that if a Dockside Green-type process were to be installed at that particular location, its capacity would have to be 35 times larger than Dockside Green's. Again, how realistic is that? It is obvious that the current footprint of the pumping station in Oak Bay would not support a plant that is 35 times larger than the Dockside Green facility, even if is placed underground, as has been proposed. It might, however, fit into a big chunk of adjacent Windsor Park. But where, pray tell, are the 14 other distributed plants supposed to go within the CRD region, and how are regulatory approvals going to be obtained for any and all of these sites, given previous opposition to Haro Woods, McLoughlin Pt, Viewfield Road and the Hartland Landfill as potential sewage treatment sites?
Another drawback of a distributed sewage treatment model is that each of the fifteen distributed plants would, according to sewage engineer Chris Town from Urban Systems, require its own, dedicated outfall pipe, plus emergency backup outfall pipe.
Lastly, for the sake of argument, let's just assume that 15 Dockside Green-size plants were scattered across the region, in an effort to meet the CRD's current sewage treatment needs. Collectively, those plants would provide a total of 5,700 m³ per day of sewage treatment capacity, or a mere 5% of the CRD's treatment needs. Thus, a distributed plan, along the lines of the one currently being touted by a grassroots group, would be capable of treating only one twentieth of our regional sewage. This begs the question: how and where is the other 95 percent going to be treated, if not in the neighbourhood plants? Viewed another way, if 15 Dockside Green-type plants were spread around the region, treating all of the CRD's liquid waste at those sites would require each of them to have twenty times the capacity of the actual Dockside Green facility.
The long and the short of it is, the figures associated with the alternative, decentralized tertiary sewage treatment plan for the CRD, which uses Dockside Green as a model, just don't add up. The Dockside Green model might work for certain areas of the CRD, particularly on the Westside, but not for the CRD as a whole. Thus, the best plan is still one which includes as few sites as possible- preferably one, large, centrally-located facility, at a location such as Macaulay Pt, where there is already an outfall pipe and where there is ample land that is surplus to DND's needs. DND could be induced to supply the land to the CRD in return for free heat recovery from the plant over its lifespan. This is the kind of solution to the sewage treatment conundrum the CRD should be exploring- not the decentralised or distributed model using the cookie cutter Dockside Green model.
Sincerely,
Gerald Graham, Ph. D.
[1]Dockside Green only has a current capacity of 180 m³ per day, and is using only about 55 m³ per day of that capacity at the current time. In order for the facility to reach the licensed, maximum capacity of 380 m³ per day, plant and equipment would have to be upgraded.