Impacts of power plants on watercourses

Helsingin Energia’s power plants conduct into the waterways cooling waters (sea water), waste waters from the processes, neutralised effluents from the water treatment plants and laboratories, and washing waters from the air pre-heaters and electrostatic precipitators. In addition to these, clarified slag quenching waters, leakage waters from the deep storage for oil, surface runoff waters from the coal store and rainwater are conducted into the sea. However, most of the waste water discharge is cooling water.

The power plants do not burden the waterways in their regions

The Environment Centre of the City of Helsinki studies and monitors the impacts of the industrial waste waters of power plants on sea water. Waterway monitoring is statutory: it was started with respect to the Hanasaari and Salmisaari power plants in 1975 and the Vuosaari power plants in 1990.

Since 1994, the Environment Centre of the City of Helsinki has also monitored the impacts on waterways of the coal stockpile built close to the Vuosaari power plants. Separate reports have also been drawn up on the impact of power plants on waterways. Monitoring includes analysis of surface and groundwaters in the surroundings of the coal store.

Helsingin Energia also carries out independent measurement and monitoring of the discharge, suspended matter and hydrocarbon contents, water acidity, temperature and the rise in the temperature of waters it conducts into the waterways. The results are reported monthly to the regional and local environment centre.

Based on the waterway monitoring, not one of the power plants located in Helsinki has burdened the waters of its area, but there have been other reasons for it:

  • The Hanasaari area has earlier been strongly burdened by residential waste waters. Water quality has improved considerably since 1987 when the waste water previously conducted to Vanhankaupunginselkä was transferred to outside Katajaluoto by the open sea.

  • Water quality in the Salmisaari area has improved substantially since 1978 when the Rajasaari wastewater treatment plant ceased operation.

  • The area of obtaining cooling water and the waste water discharge areas of the Vuosaari power plants are located within the area of impact of scattered loading from land, and therefore the loading part of the discharge waters from the coast is more significant than the industrial waste waters of the power plants.

  • Chloride contents on the eastern and southwestern side of the Vuosaari coal store have increased according to a study carried out during monitoring. According to estimates, the chloride comes from the base structure of the coal store, not from the stored coal. However, chloride plays an insignificant role in the discharge waterways because the typical chloride content in the Gulf of Finland is about 5,000 mg/l and the highest measured chloride contents have been approx. 8,000 mg/l.