WASTEWATER CONTROL

The Holyrood Thermal Generating Stationís wastewater treatment plant treats the wastewater resulting from the combustion of fuel and run-off from the solid waste landfill. Components of the wastewater from the plant are measured and compared to regulatory limits. Once all aspects of the wastewater meet provincial regulatory requirements, the wastewater is released into the environment. In 2005, 6.29 million litres of wastewater were treated and discharged, which is a slight decrease from the 6.74 million litres of wastewater processed in 2004.

AIR QUALITY MANAGEMENT

Hydro relies on both hydroelectric and thermal generation to meet customer needs for electricity. The operation of the Holyrood plant is highly dependent on the availability of water in our hydroelectric reservoirs. Water levels in our reservoirs vary annually with the amount of precipitation and runoff. When water levels increase in the reservoirs, the demand on thermal generation decreases, as does associated air emissions. The opposite is also true.

Total emissions were lower in 2005 than 2004 as a result of a greater percentage of hydroelectric as opposed to thermal generation enabled by increased inflows in the reservoirs. Concentrations per unit of fossil generation increased on account of lower average unit output levels. System emission ratios, with the exception of NOx, decreased due to greater hydroelectric production and greater purchases of energy. The NOx emission ratio did not decline because of a significant increase in the calculated NOx emissions from small diesel plants in isolated areas in the province.


PARTICULATE EMISSIONS

As part of an agreement with the Department of Environment and Conservation, Hydro conducts stack testing for the rate of particulate emissions at the Holyrood plant biannually. Testing conducted in April 2005 indicated the emission rate for particulate was 30.7 grams per second (g/s). This is the average emission rate for all three units from stack emission testing conducted. This is considerably higher than the average emission rate identified in 2003 (10.6 g/s) and is more comparable to average particulate emission rates recorded in 2001 (23.5 g/s) and 1999 (38.1 g/s). The increase in particulate emission rate compared with 2003 is partly

attributable to testing of a fuel additive on one of the generating units during the winter of 2004/2005 that may have added to the particulate emissions. However, particulate emissions from all three units were higher in 2005 than in 2003.

In 2005, Hydro made a decision to burn cleaner fuel at the Holyrood plant. The maximum fuel sulphur content will be reduced from two per cent to one per cent by mid-2006. The decision will significantly improve on air emissions from the plant. The cleaner fuel is expected to decrease the annual sulphur dioxide emissions by 50 per cent and reduce particulate emissions by 40 per cent. The cost for cleaner fuel will be marginally higher, but Hydro believes it is the right investment for the plant, stakeholders in surrounding communities, and the environment and tom facilitate compliance with regulatory requirements.

STACK EMISSIONS TESTING AND MONITORING

Stack emission testing, conducted every two years, was performed on the three generating units at Holyrood during April 2005. The tests monitor total particulate, particulate particle size, metals, sulphates, SO2, NOx, CO and CO2 in the exhaust-gas.

Test results are reported to the Department of Environment and Conservation to satisfy an existing agreement, and are used for on-site evaluation, the annual report on air emissions, exhaust-gas modeling, and reporting to Environment Canada through the National Pollutant Release Inventory and Greenhouse Gas Emissions Reporting. The results also provide data on our initiatives to improve overall unit performance and efficiency.

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