Scope & Necessity of Subsoil Decontamination Actions
In cases where there is a plan to develop or improve polluted areas, either due to a change in use after an expropriation or due to neighboring areas with sensitive environmental recipients (settlements, water resources, ecosystems), the implementation of subsoil decontamination measures is considered to be absolutely essential.
The apparent and proven contamination of the subsoil has a variety of negative impacts both on natural and man-made environments. In particular, subsoil pollution has a negative impact on:
The quality of surface and groundwater
Subsoil pollution, through the process of sedimentation, leads to alteration of groundwater physicochemical characteristics as well as surface water (such as surface drainage). These include pH and oxygen content, thus affecting all chemical and biological equilibria. Some of the immediate consequences are the disturbance of nutrients’ balance such as nitrogen and phosphorus, leading to eutrophication, toxic effects on aquatic fauna and flora, and sediment at the bottom that constitute a permanent source of pollution.
The flora and the wider ecosystem
Most chemicals and petroleum products have phytotoxic properties, causing damage such as: growth inhibition, plant disorder, nutrient imbalance, yellowing or chlorosis of the leaves.
Contaminated soil in an area constitutes an immediate danger to humans as there is an adequate concentration of chemicals to cause harm. A chemical may cause: Toxic effects, Allergies – Irritations, Carcinogenicity, Genetic mutation. Negative effects can be caused by either direct human contact with the chemical (absorption through the skin, inhalation of dust from the contaminated soil and inhalation from pollutants exhaustion into the atmosphere) or indirectly through the consumption of plants and water exposed to pollution (and generally through the food chain).
Structure condition of nearby buildings and materials
Various chemicals cause corrosion in inorganic materials such as cement, concrete and in organic such as plastics. Especially critical is the erosion of pipes that pass through the contaminated area, notably drinking water supply network.
The safety of workers and residents
There are many cases where environmental pollution of the subsoil has caused accidents in industrial facilities, resulting in the human death or injury. For example, leakage of volatile petroleum products (eg petrol) from underground tanks or gillnets at service stations may cause migration of volatile substances through permeable geological backgrounds and their accumulation in adjacent underground areas where it is possible to create a condition of explosive atmosphere that can be easily triggered by a single spark.
The aesthetics of the area
The deprecated image of a polluted field contributes significantly to the deterioration of the aesthetics of the wider region. Foul smell produced by volatile organic compounds found in contaminated soils or surface waters, or from natural biodegradable products (methane, hydrogen sulphide) can cause complete depreciation of the contaminated area itself as well as all neighboring areas. Abandoned contaminated areas become osbolete, and in time, are destined to become recipients of further pollution usually by uncontrolled waste disposal (debris, various solid and liquid waste) unless immediate measures are taken to rehabilitate and remediate the subsoil .
In the economic and social development of the region
The contaminated soil of an area can not be exploited in any way, therefore potentially arable land, a development area, or perhaps a place of recreation is lost. This affects not only directly polluted areas but extends to the surrounding areas given that no one wants to live or operate in an environmentally degraded area. The value of land and housing is deteriorating, as well as the quality of life due to the phenomenον of pollution transportation through air and water. There are impacts associated not only with rehabilitation costs, but also with the value of land, its use, and the way communities are affected.