Responsibility
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Constructed Wetlands
SaskPower is committed to sharing the long-term responsibility of a clean and biologically diverse environment for future generations. Our constructed wetland is one of several long-range initiatives that we're undertaking to meet that commitment.
SaskPower wetland: A North American first
The SaskPower constructed wetland, built in 1994 near the Estevan sewage
lagoons, is one of the largest of its kind in Canada and the only one in
North America providing cooling water to a power station. This environmentally
friendly source of cooling water is cost-efficient and requires little maintenance.
The wetland provides up to 40 per cent of Shand Power Station's annual cooling water requirements, while purifying the City of Estevan's secondary sewage wastewater and eliminating the need for semi-annual releases of Estevan's lagoons to the environment. In conjunction with the wetland, the adjacent 117-hectare duck pond provides a marsh habitat for various wildlife and migrating waterfowl to nest each spring.
Mother Nature purifies the wastewater
The wetland process
depends on plant growth and is operational from May to October each year.
Approximately 500,000 cattails were transplanted by hand to the wetland
from marsh areas in the Souris River Valley. In addition, bulrushes were
hydroseeded by mixing bulrush seed with water and spraying the mixture
over the wetland "cells." The plants filter and purify
the effluent pumped from the City of Estevan's sewage lagoons. During the
winter months, the city can store the effluent for up to 180 days. Wetland
plant life, soil, microbes, ultraviolet light and aeration act as natural
purifiers, reducing nutrients, suspended solids, biochemical oxygen demand,
heavy metals, bacteria and viruses by 70 to 95 per cent. Together with
the oxygen-rich environment provided by the water motion, the bacteria
transform the sewage water into usable water.
Regular sampling and chemical analyses are conducted on sewage inflow, wetland outflow, soil, plant material, and groundwater to monitor the efficiency of the wetland and to determine any interaction between the wetland and the surrounding environment.
Facts and figures
| Entire constructed wetland size (including holding pond): | 32 ha (80 acres) |
| Size of each cell: | 12 ha (30 acres) |
| Soil dike height: | 1.5 m (5 feet) |
| Average water depth cattail and bulrush zones: | 20 cm (8 inches) |
| Average water depth deeper water area: | 60 cm (2 feet) |
| Peak flow to Shand pipeline: | 130 l (34 gallons) per second |
The wetland consists of two main cells, each divided into subcells approximately 700 metres long and 60 metres wide (1). Each cell has three water flow paths (2). The paths can be isolated to allow partial shutdown of the system without affecting the overall output. A soil dike (3) surrounds the wetland and contains the water. Water is pumped into each cell and flows through alternating zones of cattails and bulrushes (4). A deeper, plantless water area (5) allows the wind to get at the effluent and complete the clean-up process. The treated water is discharged into the wetland holding pond (6). A return pump house (7) and a valve house (8) pump the treated water through the return pipeline (9) to the existing Shand Power Station pipeline (10).
Constructed Wetland tours
Tours of the constructed wetland are available between May and September
by appointment. Tours can be arranged in advance by calling (306) 637-4259
(Estevan) or by emailing Environmental Programs.
