The Environmental Protection Act 527/2014 Chapter 14 addresses the cleaning of contaminated soil and groundwater:

• The party responsible for causing the contamination of soil or groundwater is obliged to clean the contaminated soil and groundwater (contaminated area) to a state where it poses no danger or harm to health or the environment.
• If waste or other substances that may cause contamination have entered the soil or groundwater, the responsible party must immediately notify the supervisory authority.
• If there is reason to suspect contamination of soil or groundwater, the party responsible for cleaning must investigate the area’s contamination and the need for cleaning. The report must be submitted to the state supervisory authority, Hämeen ELY Centre.

Littering may differ from the contamination of soil and groundwater.