The Dawson Creek Reclaimed Water Project
An innovative partnership in responsible water management between the City of Dawson Creek and Shell Canada.
The Reclaimed Water Project
A key strategy in water management is to take less from the water supply and make better use of what is taken. The City’s water reclamation project, a partnership between the City of Dawson Creek and Shell Canada, does exactly that.
In 2006, concerns were raised about increasing industrial use of potable water and the ability to meet future regulations for the treatment of wastewater. City staff proposed a possible solution by finding a better use for treated effluent released from the City’s sewage lagoons.
The investigation into the reclaimed water project started by asking if and how it could be done without a large capital investment. Consultations with the public and industry included public meetings in January and February of 2010. A request for proposals was issued and Shell Canada was selected as a partner for the project.
Wastewater Treatment System
Dawson Creek has over 80 km of sanitary sewer collection piping ranging from 200 mm to 600 mm in diameter. There are nearly 3,600 residential and 600 industrial connections to this sanitary sewer collection system.
The waste collection system is primarily a gravity system; however, there are several small lift stations throughout the City and one large lift station prior to the treatment system.
There is also a vactor truck dumping station where domestic sewage is hauled in from rural areas for disposal and treatment.
The City of Dawson Creek’s Wastewater Treatment System treats an average of 5,500 m3/day.
Reclaimed Water System
The reclaimed water system draws wastewater from the City’s existing aerated lagoon wastewater treatment system. It then treats the water using Submerged Attached Growth Reactors (SAGR) built adjacent to the lagoon system.
Effluent from the SAGR system is further polished using coagulation and disc filtration equipment housed within a new building on the project site. The treated water is disinfected and stored in a wet well below the building.
Tip: Hover over the numbers for more information on that part of the system.
Two aerobic ponds containing oxygen for organisms that function in an oxygen rich environment.
SAGR Cells: Submerged Attached Growth Reactor Cells
The system consists of a submerged aerated gravel bed with a horizontal flow distribution chamber at the front end to distribute influent wastewater across the width of the entire cell.
The submerged gravel provides the necessary surface area for growth and attachment of nitrifying biomass within the bed, and is sized to optimize bacterial growth and hydraulic flow. A horizontal collection chamber at the end of the treatment zone collects the process effluent.
The SAGR system was specifically designed for cold temperature conversion of ammonia to nitrates following traditional treatment in lagoon systems, which may experience winter temperatures as low as 0.5°C for up to five months. The beds provide year-round nitrification that meets ammonia discharge permit requirements.
One large polishing pond referred to as a facultative pond, which facilitates the environment of facultative organisms capable of oxidizing dissolved and suspended organics. There are also anaerobic and aerobic bacteria within certain layers of the pond.
The oxygen for the aerated ponds is provided by two 150 HP blowers through 10,000 feet of air lines woven through the aerated cells.
Wastewater treatment is essentially a natural process where organisms, present in the environment, break down the waste by using it as a food source. The process is enhanced by the addition of oxygen in the second stage of treatment so that a more concentrated population of these organisms can survive together.
The effluent is metered and sampled regularly. The results of the sampling are sent to the Ministry of Environment to ensure that the quality meets the requirements of our permit.
In addition to the sanitary sewer system, there is a separate large storm water collection system consisting of over 35 km of pipe ranging from 300 mm to 1200 mm in diameter. This is treated to “unrestricted access” meaning, to the highest treatment standard for effluent.
THE RECLAIMED WATER TREATMENT PLANT
The Dawson Creek Water Reclamation Plant opened in September of 2012 with the capacity to produce 4,000m3 of reclaimed water per day. Shell retains the rights to the first 3,400m3 per day that ships by pipeline 48 km to their Groundbirch gas field operations west of Dawson Creek.
The City retains the rights to 600m3 of reclaimed water for resale to industry or for municipal use.
Construction of the reclaimed water project included a LEED-certified treatment facility, a new municipal reclaimed water truck filling station, a Shell Canada owned and operated pump station and a pipeline to transport the reclaimed water to Shell’s field operations.
Although the water is adequately treated upon leaving the SAGR cells, it is further polished in the treatment plant by coagulation and disc filtration to meet water quality requirements. The water is chlorinated to disinfect prior to distribution for oil and gas activities and municipal use.
There is a water truck filling station at the treatment plant for municipal sales of water to industry and the filling of City water trucks.
The Shell Canada owned and operated pump station transports the reclaimed water 48 km to Shell’s field operations at Groundbirch by pipeline and has a filling station for water hauling.
British Columbia currently has four categories or levels of treatment for reclaimed water. The water produced at the facility meets the quality requirements for three of those categories, providing a wide range of reuse opportunities.
Two anaerobic ponds containing little or no oxygen for organisms that require an oxygen-free environment.
Uses for Reclaimed Water
Special consideration was given to the uses for the reclaimed water, and to how it would be handled in the field. Because reclaimed water reduced the discharge to Dawson Creek, careful consideration was given to the potential impacts on fish habitat determined by monitoring the creek during the commissioning period.
The treatment system has proven itself in the northern environment and has met water quality standards during the first year of operation.
Shell uses the reclaimed water in its fracturing operations near Dawson Creek. Piping the reclaimed water to Groundbirch reduces traffic, noise and dust, which are among the top concerns of local landowners. The pipeline is expected to eliminate 3 million km a year in truck trips over the full course of gas field development.
On September 18, 2014 the City’s permit was amended to include the use of reclaimed water for street cleaning, sanitary flushing, storm flushing, dust control and construction.