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Groundwater and springs

What is groundwater?

Groundwater means freely moving water in the ground that is formed when rainwater seeps through the ground into a groundwater table. A groundwater table sits on an impermeable formation underground, such as a layer of rock or clay, and flows slowly downhill due to gravity. The surface height of groundwater varies according to the seasons and is dependent on the amount of rainfall, as well as the melting of snow and frost.

Use of groundwater and groundwater area classification

The most important groundwater areas are classified according to their suitability for supplying water for household consumption. Groundwater areas that are considered to be important for the water supply, or class I areas, in Helsinki are the Tattarisuo, Vartiokylä, Vuosaari, Santahamina and Isosaari groundwater areas, as well as part of the Fazerila groundwater area, which is located primarily in Vantaa.

Groundwater areas are currently not used to supply water for household consumption in Helsinki. The Tattarisuo, Vartiokylä and Vuosaari groundwater areas are currently Helsinki’s emergency water supply areas, which can be used to supply water in crisis situations. A protection plan was drawn up in 2003 for the Tattarisuo, Vartiokylä, Vuosaari and Kallahti groundwater areas.

There are also numerous private wells in Helsinki, which are used to supply water for household consumption and other uses.

Groundwater monitoring

The City of Helsinki monitors the surface height of groundwater in Helsinki. The Helsinki Region Environmental Services Authority also monitors the quality of groundwater in class I groundwater areas. The owners of private wells can request water laboratories to carry out well water analyses of their wells.

Groundwater supply and permits

The building of a simple domestic well in your own property does not require a separate permit. Drawing water from someone else’s land or drawing over 250 m3 of water per day requires you to apply for a permit from the Regional State Administrative Agency of Southern Finland.

Construction in class I groundwater areas and groundwater protection

Construction in class I groundwater areas in Helsinki follows the ”Rakentamistapaohje tärkeälle pohjavesialueelle rakennettaessa” (Construction method instructions for construction in important groundwater areas). According to the instructions, the building permit application for a class I groundwater area must include a groundwater management plan and a related groundwater monitoring programme.

The quality of groundwater shall be monitored at the construction site with a groundwater sample taken before construction is started, and another sample taken after construction is finished. If the construction results in the contamination of groundwater, the party responsible for the construction can be obligated to purify the groundwater in accordance with the Nature Conservation Act.

Springs

A spring is a place where the groundwater surface naturally meets the ground surface. The springs of Helsinki have been historically important water supply sites, due to which many of them have wells or other structures built around them. Although the expansion of the city has resulted in the destruction of numerous springs, a few dozen springs still remain in Helsinki, though only a few of them are still in their natural state. 

Known springs are listed in the Helsinki Nature Information System.

There are a few dozen springs in Helsinki. Water is visible in brook and boghole springs, of which there are around ten. There are also some ten springs in Helsinki that have been converted into wells, half of which are at least intermittently dry. There are also at least 13 seepage surfaces (areas where groundwater seeps to the surface but is not necessarily visible) in Helsinki. Currently, the Environment services does not regularly monitor the water quality of springs.



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12.10.2018 13:12