Wastewater is treated using aerated ponds and UV disinfection, and then used to irrigate forage land and a waterfowl nesting wetland that also serves as a popular recreation site.
Project Summary
The City of Cranbrook operated an effluent spray irrigation system since the 1970’s as part of its wastewater treatment facility. A 2009 legal ruling from the BC Environmental Appeal Board mandated that the effluent storage ponds could not exceed a certain level, lowering its storage capacity and triggering the need for an upgrade. To identify a solution, city staff and consultants conducted a SWOB exercise (strengths, weaknesses, opportunities and barriers) before engaging with a Value Improvement Specialist. The specialist led a 3 day session that brought together experienced engineering, groundwater and environmental professionals to determine possible practical solutions to the issue and a vision.
After receiving the support of city council, Jamie Hodge, the Director of Engineering Services, led the upgrades to the City’s wastewater treatment system in 2010. The improvements included a new storage pond, two new disinfection facilities and enhancements to its aerated lagoon. At the same time, the City decided to retrofit an agricultural irrigation system that reuses the wastewater on agricultural land. To enhance the quality of water, fine bubble aeration and UV disinfection are used to lower total suspended solids, biochemical oxygen demand and phosphorus levels.
To improve the energy efficiency of its water treatment plant, the City of Cranbrook installed low pressure irrigation heads, eliminated pipeline restrictions to minimize pumping energy, and added automated monitoring pivot irrigation systems.
Lessons Learned
It is important to create a long-term vision and review the entire system when making upgrades to wastewater treatment systems. In order to garner support for the vision and project from city council and various stakeholder groups, it is essential to engage with council and the community early, broadly and extensively including with First Nations, provincial agencies, general public, and businesses.
The use of proven products and technologies in innovative ways in addition to thinking differently from generally accepted or conventional approaches can be valuable when instituting improvements to these systems based on the city’s experience. The City of Cranbrook also conducted a value engineering exercise at the design stage to establish an optimal return on investment as well as performed extensive research (e.g. feasibility and pre-engineering studies). It encourages other local governments to do the same.
More details about the tools & technologies related to this case study:
Recover Water & Materials
Wastewater Reclamation
Nutrients from Wastewater
Energy Savings/ GHG Reductions
> Reduces energy use by 750 to 1,000 MWs per year, enough to power 160 – 190
homes.
> Energy recovery will reduce the waterworks total GHG production to 9 tonnes
CO2e, a reduction of over 60%.
Business Case
BC Environmental Appeal Board issued order that the level of one of its effluent storage ponds not exceed a certain level, which lowered its storage capacity. A solution was needed.
Prepared for 100 years of effluent disposal
Upgraded wastewater treatment plant can accommodate population growth and commercial / industrial development for at least 20 yrs.
Lower annual maintenance costs
Residential sewer use fees have declined (e.g. $20/month in 2016)
600 cow-calf pairs forage on the irrigated land from May to November.
The land produces 3,600 tonnes of hay a year, which sold in 2017 for $690,000. Ranchers and the municipality share this revenue, with the City receiving 35-40%
Co-Benefits
Meeting the Canadian Council of Ministers of the Environment (CCME) guidelines for discharge of treated sewage to surface water
Lower water consumption due to use of high efficiency spray nozzles
Higher quality effluent better protects wildlife, aquatic life and vegetation reduced odour due to use of fine bubble diffusers in lagoons, resulting in less public complaints
New spray technology waters nearly 1800 acres of feedstock fields, which raises crop production and supports beef cattle production
Irrigation site is popular for recreation activities (e.g. walking/hiking and bird watching)
School and public tours showcase the science and how the site works with nature
Project Cost & Financing
Total Project Cost: $28 million
Funding sources:
$9.6 million from Infrastructure Stimulus Funds from the
federal and provincial governments
$8.5 million from the Gas Tax Fund
$9.2 million from the City
$660,000 grant from FCM’s Green Municipal Fund and a loan through its low interest rate program
Project Summary
The City of Cranbrook operated an effluent spray irrigation system since the 1970’s as part of its wastewater treatment facility. A 2009 legal ruling from the BC Environmental Appeal Board mandated that the effluent storage ponds could not exceed a certain level, lowering its storage capacity and triggering the need for an upgrade. To identify a solution, city staff and consultants conducted a SWOB exercise (strengths, weaknesses, opportunities and barriers) before engaging with a Value Improvement Specialist. The specialist led a 3 day session that brought together experienced engineering, groundwater and environmental professionals to determine possible practical solutions to the issue and a vision.
After receiving the support of city council, Jamie Hodge, the Director of Engineering Services, led the upgrades to the City’s wastewater treatment system in 2010. The improvements included a new storage pond, two new disinfection facilities and enhancements to its aerated lagoon. At the same time, the City decided to retrofit an agricultural irrigation system that reuses the wastewater on agricultural land. To enhance the quality of water, fine bubble aeration and UV disinfection are used to lower total suspended solids, biochemical oxygen demand and phosphorus levels.
To improve the energy efficiency of its water treatment plant, the City of Cranbrook installed low pressure irrigation heads, eliminated pipeline restrictions to minimize pumping energy, and added automated monitoring pivot irrigation systems.
Lessons Learned
It is important to create a long-term vision and review the entire system when making upgrades to wastewater treatment systems. In order to garner support for the vision and project from city council and various stakeholder groups, it is essential to engage with council and the community early, broadly and extensively including with First Nations, provincial agencies, general public, and businesses.
The use of proven products and technologies in innovative ways in addition to thinking differently from generally accepted or conventional approaches can be valuable when instituting improvements to these systems based on the city’s experience. The City of Cranbrook also conducted a value engineering exercise at the design stage to establish an optimal return on investment as well as performed extensive research (e.g. feasibility and pre-engineering studies). It encourages other local governments to do the same.
