Construction site water

In Espoo, the treatment of construction site water must be planned and implemented in accordance with the Helsinki Metropolitan Area’s construction site water guidelines. The guidelines compiled by the environmental protection authorities and HSY Water Services provides guidance for high-quality construction site water management, including the handling, design and quality requirements of construction site water and related requirements.

Helsinki Metropolitan Area Construction Site Water Guidelines(external link, opens in a new window) (in Finnish)

The sensitive water body might not be located right next to the construction site or otherwise easily detectable, so it is important to check in the city’s map service already at the planning stage whether the construction site is located in the area of a sensitive water body.

Sensitive water bodies are particularly vulnerable to changes in pH and elevated solids concentrations due to their small water volume, valuable species, recreational use or natural state. The construction site is considered to be in the area of a sensitive water body if it is less than 200 metres from the water body “as the crow flies.”

Check the locations of sensitive water bodies in the City of Espoo’s map service(external link, opens in a new window). To view sensitive water bodies: Select what information is shown on the map – Environment – Sensitive water bodies/Herkät vesikohteet. The map shows a zone of 200 m around the water bodies. If the construction site or part of it is located in the zone, the construction site is considered to be in the area of a sensitive water body. 

The fine aggregate and sludge formed by the drilling of a geothermal well must be treated in such a way that it does not cause harm to the environment, neighbours or the sewer network. When drilling water is purified and discharged back into the environment, it must be at least as clean as natural water.

The municipalities of the Helsinki Metropolitan Area and HSY have jointly produced a special guide on the water treatment of geothermal well sites. The principal designer and the contractor entering the project must follow the guide and ensure that it is also used by the drilling contractor.

Guide on the treatment of geothermal well drilling water and other guidelines related to geothermal wells (in Finnish)

The construction site may have been granted an environmental or water permit or a decision on the remediation of contaminated soil or groundwater. If the decisions contain provisions concerning waters to be discharged from the construction site, the construction site must follow them instead of the general construction site water guidelines for the Helsinki Metropolitan Area.

If construction site water is going to be discharged into the stormwater, wastewater or mixed sewerage water drainage system, contact Helsinki Region Environmental Services HSY. Read more in HSY’s site water drainage guidelines(external link, opens in a new window) (in Finnish).

If the activity may cause environmental contamination, apply for an environmental permit from the Regional State Administrative Agency for Southern Finland (AVI). At a construction site, this may be the case, for example, when environmentally harmful construction site waters are, for a long time, discharged into a stormwater drain or directly into the water system.

Read more about the environmental permit at Environment.fi(external link, opens in a new window) (in Finnish).

If the activity significantly changes the water system, aquatic environment or groundwater conditions, apply for a water permit from the Regional State Administrative Agency for Southern Finland (AVI). At a construction site, this may be the case, for example, if the main drainage channel has to be moved or the pipe is dug under the channel.

Read more about the water permit at Environment.fi.(external link, opens in a new window)

Environmental protection regulations of the City of Espoo concerning construction site waters (section 7)

Starting a construction project and permits in Espoo

Answers to questions about construction site water can be found from the frequently asked questions about water -page.