It focuses public attention upon the future public costs that result when government authorities approve urbanization in storm water drainage basins. However, the frustration of St. John’s Couns. Sandy Hickman and Danny Breen with the lack of progress on the planned construction of a weir (dam) at Long Pond in Pippy Park is misplaced. The Pippy Park Commission should not be viewed as a bothersome obstacle to this project, but rather as an organization that thoroughly understands its mission.
The commission should be an integral component of all decisions that impact upon the ecosystem which it has been given the legal responsibility to protect.
The Rennie’s River system is part of a natural storm water drainage basin that has been compromised by the construction of the north campus of Memorial University and the Health Sciences Centre. Environment Canada has estimated that urbanization of such a natural drainage basin can result in storm water being increased by 400 per cent. When storm water drains over impervious surfaces absorbing fertilizers, detergents, plant debris, gasoline and animal droppings, these pollutants accumulate during dry periods and are flushed into lower elevations during the next rainfall.
There have been several weather events that have caused flooding in the river system in recent years. In an attempt to control future flooding and downstream property damage, the city’s consultants have recommended that a weir be constructed adjacent to the bridge at the outfall of Long Pond. This will, no doubt, control the rate and volume of water that flows into Rennie’s Mill River. However, in due course, it will also raise the level of the water in Long Pond, thus reducing the existing natural outflow rates during rain storms, and increasing the pollution and sedimentation in the pond.
The Pippy Park Commission is not the only organization concerned about this situation; NatureNL members have also raised red flags on what the sudden change might mean for the pond-area ecosystem. Construction of the weir should not be undertaken in the absence of long-term functionality, which is totally dependent upon future rainfall events.
To further complicate the problem, the planners have to deal with the reality of not knowing what the intensity and duration of rainstorm events will be 20 years from now. The environmental research indicates that rainstorms will be more intense and prolonged, but we really do not know what the degree of intensity or the duration may be. If you were to ask climatologists what the duration and intensity of a severe rainstorm event 20 years in the future will be, or even two years, they would only have access to past patterns to predict the future.
The weir that is being recommended by the consultants is unlike a hydroelectric dam, which can control flooding by diverting the excess water into another channel that bypasses the generating station. This option is not practical for the weir being proposed in this case, and we can assume that continued flooding will cause excess water to flow over the top of the dam.
The proposed weir for Long Pond therefore appears to be a high-risk undertaking and the future costs of protecting the ecosystem of the water basin, as well as protecting public and private properties downstream, are unknown.
The city’s long-term plan should be to return this important rainwater basin to its original functionality by relocating those north campus buildings to a more ecologically appropriate site when they become obsolete. In the meantime, further construction along the Rennie’s River system must not be allowed to exacerbate the problem that already exists.
Long Pond has been an integral component of recreational activities of St. John’s long before the original buildings of Memorial University were constructed. Instead of spending more money on the high probability of ineffective flood abatement infrastructure, more thought should perhaps be focused upon creating retention ponds upstream and downstream of the Long Pond catchment area, and, in due course, returning Long Pond to an efficient natural ecosystem that is structured to accommodate unexpected and unknown rainfall events and where future damage can be mitigated.
N.V. Bruce Pardy