Prior to the Safe Clean Drinking Water Project, water delivered to Saint John residents was coarse screened and chlorinated. This unfiltered surface water contained significant amounts of disinfection byproducts, at levels that often exceeded those prescribed by current standards. These byproducts, together with the inability of the system to adequately treat potentially harmful protozoa such as giardia and cryptosporidium, created a risk to public health. This unfiltered water, with a low pH, is highly corrosive which results in damage to the water system.
The Safe Clean Drinking Water Project was undertaken to address these issues and provide city residents with safe, clean drinking water which meets Canadian and New Brunswick standards.
The City decided to use design-build delivery for the following reasons:
- To ensure that the City’s design, operational, and lifecycle performance criteria were met
- To achieve the optimum balance of risk transfer between the City and the design-builder whilst maintaining a focus on whole lifecycle costs
- Value for money analysis
- Foster competition via a request for qualifications short-listing process; only short-listed teams were allowed to participate in the request for proposals phase
- Benefit from the private sector’s innovative solutions and best practices for similar projects
- Ensure a fair and transparent procurement process
The project consisted of design, construction, operation, rehabilitation and financing of raw water source and transmission system improvements, a new drinking water treatment facility and water storage facilities, industrial system improvements in East Saint John, and the implementation of a groundwater system and treatment in West Saint John.
There were thirteen components of work grouped into five categories, which together were required to address the technical objectives of providing city residents with good quality water, providing an adequate supply of water for customer use and fire protection, and rehabilitating the water supply system. Categories 1 and 2 are comprised of a new 20 MGD water treatment plant and 8.7 MG of new storage reservoirs. Categories 3, 4, and 5 included various improvements to the water source infrastructure, construction of new water mains, the rehabilitation of selected existing water mains, well site development and related improvements.
Water quality objectives are met by treating the raw water using the following processes:
- Raw water inlet structure including fine screens
- Oxidation through potassium permanganate dosing; pH and alkalinity adjustment
- Enhanced coagulation and slow mixing for flocculation
- Clarification with high-rate dissolved air flotation (DAF)
- Dual-media rapid gravity filtration
- Chlorination for primary disinfection purposes
- UV disinfection through medium-pressure UV reactors
- Corrosion control through orthophosphate dosing
- Chlorination for secondary disinfection purposes
- Residual treatment by thickening and dewatering
This project was technically complex due to the separation of the city water system. The existing network of water mains, pressure zones, and storage reservoirs was improved to meet current standards for reliability, hydraulic functionality, and the maintenance of water quality. System limitations were addressed, and aging infrastructure replaced or rehabilitated so that good quality water suitable for its intended use and at adequate pressure can be delivered to consumers across the city. The project is scheduled to be completed on time and on budget for the City of Saint John. The average number of daily workers on the project was 172, involving 775 local workforce personnel, and five permanent jobs were created due to this project.
Mayor of SJ, New Brunswick Don Darlin talks about the plant in this video: