General Questions
Why do we need to treat our wastewater?
Sewage treatment is an important component of a healthy and viable community.
- Dawson currently pumps about one billion litres of screened sewage (preliminary screening) into the Yukon River every year. The screening only removes the larger particles in the sewage. Screened sewage may create a toxic environment for fish in the vicinity of the discharge pipe, and may create a public health hazard in the area immediately downstream of the discharge pipe. During the term of its water license, Dawson’s sewage effluent has failed toxicity tests.
- In March 2003 the City was sanctioned by the Yukon Territorial Court and directed to implement a secondary level of wastewater treatment. The City of Dawson will face costly fines or be mandated to implement costly interim measures if the treatment plant is not completed in a timely fashion.
Both the City of Dawson and the Government of Yukon have committed resources towards the development of a sewage treatment facility.
This investment will protect and enhance the quality of the Yukon River while providing critical infrastructure for Dawson City.
What is the current status of the project?
The unique design-build contract of the project allows for input and ongoing considerations to be resolved thereby minimizing the risks to the project and owner. Together project partners are carefully considering all design requirements including: site construction, site development, project management and operation and maintenance.
With respect to assessments, approvals and permits the project has:
- Obtained a Decision Document, through the Yukon Environmental and Socio-economic Assessment (YESA) process, that is being adhered to.
- Obtained a Development Permit from the Heritage Board of Dawson City
- Obtained a Building Permit from the Government of Yukon
- Obtained a Water Licence
With respect to construction, the project has completed:
- Construction of the east and west shafts (summer 2010)
- Installation of the internal components of both shafts (fall 2010)
- Excavation for the facility (April 2011)
- Installation of a new sewage sump (April 2011)
- Installation of a new manhole for Dawson (May 2011)
How much will the proposed project cost? Who is paying?
The current contract with Corix for the Dawson Sewage Treatment Facility is $25 million. The Project is being funded jointly by the Federal Government (75%) and the Yukon Government (25%).
Part of the $25 million contract includes payment to Corix to run the plant for 12 months, and to train Dawson staff to run the new plant.
When will the Project be completed?
As of August 2011, Corix’s construction schedule projects that the plant will be operational in March of 2012. This may change, but the expectation is that the plant will be running by late spring 2012.
What are the benefits of this project to the people of Dawson City?
The Dawson Sewage Treatment Project will use less than one tenth of the space required for lagoon treatment. The facility may also use about half the power of a conventional mechanical system. This is because the plant building is smaller and does not require as much energy to operate in the harsh Yukon winters. The facility will use energy efficient components such as pumps, and fluorescent lighting and it will also capture heat generated from the treated effluent leaving the building.
The Project will:
- Eliminate the discharge of screened sewage into the Yukon River
- Reduce impacts on fish and aquatic resources
- Provide work opportunities over a two year span for northern construction companies including Construction Drilling Inc., Han Construction, Gammie Trucking Ltd, Grunt Action Inc, Complete Concrete, Ben’s Electric, Keith’s Plumbing, EBA, Pine Tree Services and Dorward Engineering.
How much will the proposed project cost? Who is paying?
The current contract with Corix for the Dawson Sewage Treatment Facility is $25 million. The Project is being funded jointly by the Federal Government (75%) and the Yukon Government (25%).
Part of the $25 million contract includes payment to Corix to run the plant for 12 months, and to train Dawson staff to run the new plant.
How does the technology work?
The deep shaft sewage treatment system (called VERTREATTM) consists of two 1 metre diameter shafts sunken 95 metres into the ground. A mixture of pre-treated sewage and return sludge flows down the shafts, where it is combined with compressed air at several elevations. The air mixes with the sewage which is critical to the health of the “bugs” (bacteria) that treat the sewage. The air mixed with sewage then flows back up to the surface through a centre pipe in the shaft to a basin that separates the sewage solids from the treated effluent by floatation.
See the Treatment page for more information.
Will the technology work in the extreme temperatures in Dawson?
The system has been designed specifically for the temperatures currently experienced in Dawson’s screening facility.
In particular, in harsh winter conditions, the building that houses the equipment is heated to ensure optimal operations. These heating costs are expected to be reasonable because of the small footprint of the building, the high rated insulation (R44 for walls and R60 for ceilings) and the heat capture from the treated effluent leaving the building.
Another consideration for infrastructure in areas that experience extreme cold is access to service that infrastructure should a breakdown happen. This is why the facility is designed with redundancy, meaning that there are extra pieces of equipment standing by to ensure ongoing operation for any maintenance, repairs or malfunctions. The extra cost for the extra equipment is included in the construction cost.
Will there be odours produced by the treatment plant?
The contract for the Dawson Wastewater Treatment Project specifies that there will be no odour at the fence line of the facility.
- The sewage enters the system underground and goes straight into a concrete holding tank.
- Air released by the system will be filtered to prevent the release of odours outside the facility.
What is sludge?
Sewage sludge is produced from the treatment of wastewater and consists of two basic forms — primary sludge (large solids that go down the toilet and sinks) and secondary sludge (bacteria that remove the dissolved contaminants from the wastewater). These are combined in the shaft and dewatered together excluding the screenings.
Sludge must be treated and disposed of in a way that makes sure the bacteria and other contaminants cannot impact the environment or human health. Sludge may be treated using a number of processes, and it may be disposed of at landfill, which is designed so the contaminants don’t leach back into the environment.
Additional treatment, such as digesting in buried conditions in the disposal trenches or composting, can allow the sludge to be used as a cover material at a landfill. The sludge in Dawson City will be dewatered and partially digested at the plant. Then it will be taken to the landfill to finish the process of digestion and drying.
How can I find out more information about the Dawson Sewage Treatment Project?
The project team is committed to a robust program of public information and consultation. Please visit the Share Your Comments page or contact the Yukon Government project manager Catherine Harwood at (867) 456-6574 or email: Catherine.harwood@gov.yk.ca
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