Plant Engineering Details
Biosolids/Organic Residuals Option
After researching eight options for biosolids/organic residuals processing, the CRD’s consultant team have chosen one strategy as a basis for reasonable formulation with the three distributed management options. Other biosolids options are still available for consideration, but choosing one to use when considering plant number and location provides a standard when assessing the three options.
Biosolids Option Details
The biosolids strategy provides for maximum beneficial reuse of biosolids through energy recovery and beneficial reuse. It would see 50% of biosolids co-digested with organics and used as a coal substitute for a cement kiln; resources from this portion would include biogas, biomethane and heat. The other 50% of biosolids would be dewatered and applied to willow coppice farms as fertilizer; willow woodchips would be harvested for a green biofuel source.
Where will biosolids be processed?
At this time, the wastewater management strategy assumes that a Biosolids Management Facility will be located near the Macaulay/McLoughlin Point Area.
The goal of the facility would be to both recover energy and create a product that can be used in a beneficial reuse program. The representative technology for the facility is thermophilic anaerobic digestion followed by dewatering and land application of the digested biosolids. The produced biogas would be cleaned to methane quality and sold to Terasen Gas. Specific processes include:
- Dewatered sludge cake rewatering and conditioning
- Primary and secondary digesters
- Biosolids dewatering
- Odour control
- Process biogas to methane quality
Biosolids management technology will likely change significantly in the years to come. The goal is to develop a biosolids strategy that offers more than one option to manage biosolids.
For addtional information on resource recovery and some of the options the CRD is considering, read about our Biosolids Strategy Evaluation.
Macaulay/McLoughlin Point Secondary Plant
While the Macaulay/ McLoughlin wastewater treatment plant would be the largest plant, the adoption of the distributed treatment strategy means that the plant will be smaller than if using a centralized treatment approach. Technologies that we could employ at Macaulay/ McLoughlin include:
- Influent pumping
- Screening and grit removal
- Biological aerated filtration
- UV disinfection
- Effluent pumping
- Heat recovery
- Water recycling
Treated wastewater would be discharged out an expanded marine outfall system.
Site Area
The secondary plant at Macaulay/ McLoughlin Point would require a site area of about 5 hectares, without resource recovery processing. At Macaulay Point, the CRD currently owns a small parcel, where the existing preliminary treatment / pumping works are located. The land required for the new plant is owned by the DND. Discussions have been ongoing for some years on acquiring additional land.
The CRD is also reviewing the option of using the tanker farm at the Imperial Oil site near McLoughlin Point in Esquimalt. Further information will be provided as it is available.
Construction & Engineering Details
Construction of the plant at Macaulay Point would require the cooperation of several parties—the CRD, the Township of Esquimalt, the Province and the DND/Federal Government. Care would be taken to ensure:
- protection and/or improvement to surrounding land
- implementation of a "good neighbour" policy, with management of odours and viewscapes
- good architectural design
Clover Point Wet Weather Plant
Our plan for Clover Point is to change the function of the facility, but keep the appearance the same. Clover Point will be a wet weather plant only. Dry weather flows will be pumped to the Macaulay Point plant via a new pump station and forcemain. This means that most of the time, there will be little or no outflow from this site. During wet weather events, pollutants will be reduced by 95% by enhanced primary treatment.
Site Area
The dry weather pump station and the wet weather treatment facility would be located underground in a similar manner to the existing works. The plant would be constructed in a single stage, with minimal disruption of public access.
Clover Point is currently owned by the City of Victoria and a legal covenant exists, defining portions of the site as park use. Neighbourhood consultation, as in the case with all sites, would be a key part of the implementation process.