A New Regional Wastewater System: 16 Communities, $325M, and 90 Miles of Forcemain

In 2005, the province of Alberta developed a new strategy for regional wastewater treatment and transmission in Central Alberta. This was done to protect the watershed along a sensitive stretch of the Red Deer River, and to provide wastewater treatment and transmission capacity for a design horizon service population of 350,000. This paper provides an overview of the entire system, starting with the new regulatory framework that set the stage for the system, from the perspective of Alberta Environment and Parks (AEP), the agency that developed the plan. On the design front, this paper compares the differing approaches to the consideration of peaking factors and wet weather flow allowances over the course of the designs of the various systems that occurred over a ten-year period, and how "lessons learned" were applied over time to inform how water conservation, infrastructure renewal, and higher utility servicing costs were addressed in the system designs. Differences in the hydraulic profiles of the systems are also identified along with how approaches to air releases, pressure sustaining valves, and vents in the systems evolved over time. The expansion of wastewater treatment capacity on an existing site will be reviewed. The paper also considers construction and constructability, with consideration to topics such as wetland preservation, the changing break points on affordability of open cut vs. horizontal directional drilling.