With the completion of upgrades at the Charlottetown Pollution Control Plant to secondary treatment, and completion of the separation of combined sewer in the Brighton area of Charlottetown, and as a continued effort to resolve the operational and environmental issues associated with combined sewer overflows, the City is proceeding with a project to separate the remaining combined sewer system within the Spring Park area. WSP has been awarded the consulting engineering services portion of the project. The project is divided into six distinct phases to be completed over a three year period (2012-2014). The drawing below provides an indication of the area included within this project.
Originally implemented with the development of the Spring Park and Brighton neighborhoods, the City of Charlottetown’s combination sewer system was considered, at the time, to be a viable option for economically providing sanitary and storm drainage systems within newly developed areas of the City. This concept of servicing, although not considered an acceptable practice by today’s standards, was recognized, in the 1950’s and 60’s, throughout North America as a practical method to economical service the rapidly growing communities. The City of Charlottetown, like many of the communities practicing this method of service, soon learned that this practice was troublesome.
Under normal dry weather conditions, the combined sewers collect sewage from residential, commercial and industrial properties, conveying the flows to the City’s Wastewater Treatment Plant before discharging the treated effluent to the environment. When very light rainfall occurs the flows within the combined sewers increase, directing a mix of the combined sewage and light rainfall to the treatment plant prior to discharging to the environment. During events of normal to heavy rain or snowmelt the capacity of the combined sewers are exceeded resulting in combined sewer overflows of untreated sewage to the Hillsborough Harbour. Extreme rainfall events cause surcharging, backups and flooding in areas serviced by the combined system. Almost immediately upon these systems entering service, the City and property owners serviced by the systems, discovered just how susceptible these systems were to overflows, surcharging and flooding. The resulting damages and concerns for public health and the environment led the City to discontinue this practice and to return to the conventional practice of building dedicated and separate sanitary and storm system.
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