In the early to mid-1950's, the Province of Prince Edward Island embarked on a new era of structure replacement, that included the then-popular creation of man-made fresh water lakes. At several watercourse crossing locations, aged large open-span bridge structures were replaced by constructing earthen road bed berms (i.e. causeways) complete with engineered hydraulic control structures which measured approximately 6.0 metres in span. Approximately two or three decades following their installation, water quality issues began to emerge in the impoundments and waterways located upstream of most these control structures. The Province has recognized the need to consider removal of the control structures, and restoration of full tidal passage at these locations in conjunction with their Structure Replacement Program. Restoration of tidal passage at these locations has been accomplished successfully by a number of engineered methods. As part of their Structure Replacement Program, the Department assesses tidal passage requirements at structure replacement locations and also develops Environmental Effects Monitoring Programs to assess associated environmental criteria, such as Total Suspended Solids (TSS), before, during and after construction project to monitor and confirm the effects of the new structures.
Abstract