Analyzing soil quality

In the previous issue we talked a lot about the pollution generated by lindane production. At the request of many of you, this time we have asked ourselves what soil characterization is and how it is done. That is, to explain to us how the first traces of pollution are found. To know it, we have approached the team that often performs these tasks: To the company Gaiker, located in the Technological Park of Zamudio. More specifically to Txomin Bargos. We hope it will serve to satisfy curiosity.

Industrial activity, directly related to the development of our economy in the immediate past, showed no great concern for the environment. In some cases it can be said that he acted negligently. This situation leads us to find everywhere a lot of pollutants emitted to the environment and especially the soil. So things, today it is essential to develop expensive research projects.

The objectives of the projects are multiple and varied: study to what extent pollution can affect our environment, characterize pollutants, etc. And if we want to know what type of future use the soil will have, we must know in detail all the features that have been mentioned, which will entail recovery or definitive loss of the soil.

In order to carry out the study of soil quality, the points that the Basque Government, through its Ihobe Public Society, determines the project called “Master Plan for Soil Protection” are taken into account. Based on these considerations, the basic steps outlined below are taken when analyzing soil quality.

Identification of potentially contaminated sites

Carrying out research work known as Inventory of potentially contaminated soils makes the road easier. In fact, in order to know if the original chemical physical characteristics of the soil have changed and to what extent they have changed, this is an essential tool and, therefore, is the first step to detect contamination.

Collection of information

Although the types of pollutants that can be found in the soil are very varied, in practice they can be divided into seven large groups and so we do in Gaiker.

This second step is to collect all the information necessary to understand the current situation. The methodology to follow is the realization of a detailed study of the environment: documentation work, direct visits, historical study, etc. The collection of information is done before the chemical study of the soil or the sampling campaign is started. In fact, it allows to know in advance the economic viability of expensive research projects. Once we have carried out a historical study, we can know, for example, the potentiality of the soil and, in some cases, some of the programs that were considered necessary cannot be carried out with the consequent economic savings.

Local research

When data obtained in previous phases confirm that the analyzed soil is contaminated, local research is usually initiated. This is the most important time for soil quality analysis and the phase that more human and material resources require.

The starting point of the study should be very clear. Needless to say, we would start working among hundreds of parameters and/or study areas if we do not define in advance what we should investigate and how we will do it. As already mentioned, there are many resources at stake and their incorrect or correct use will largely depend on the transparency of the study.

Although the types of pollutants that can be found in the soil are very varied, in practice they can be divided into seven large groups and so we do in Gaiker: metals, inorganic compounds, volatile aromatic compounds, polycyclic aromatic hydrocarbons, chlorinated hydrocarbons, pesticides and others.

The correct classification and characterization of these seven groups of pollutants is based on the importance of material resources and the need to have a laboratory equipped with high-level equipment and, of course, on the performance of the functions of a team of qualified technicians.

As for soils contaminated by HGH residues generated in lindane production, the most commonly used technique is High Definition Gas Chromatography (HRGG). Although the components of this technique can be very numerous, two are basically very precise analytical methods for the quantification of halogenated compounds, the Electron Detection Detector (ECD) and the Selective Mass Detector (MS) that allows the correct identification of the contaminant.

Data analysis and assessment

When analyzing the results obtained in previous phases, the values established by the Master Plan of the Basque Government are used. Thus, the data obtained are divided into three levels.

A value or reference level: if results above this value are obtained, it is confirmed that the soil is contaminated.

Value B or lower limit of the level of risk acceptability: if the results obtained exceed that value, it can be said that it has associated an unacceptable level of risk.

Maximum risk level C or acceptable: When results exceed this limit, soil pollution is assumed to harm human health and ecosystem functioning. This involves the implementation of soil recovery projects.

Risk analysis

In this last phase the potential and real risks arising from the alteration of soil characteristics are analyzed. In fact, we try to predict the impact of the new situation on basic performances. Thus, due to the defined risks, in human health, in the functioning of different ecosystems, in the dispersion of pollutants or in the usual uses of soil (agricultural, forestry, building, etc.) possible dysfunctions are analyzed.

What about lands contaminated by HGH waste?

Today we can say that we are able to “technologically destroy” pure HGH. The waste of about 5,000 tons in this situation is already treated with the BCD (Catalyzed Decomposition Base) technique. However, for those cases where these waste is mixed with land or other waste, the degree of development is very different. In this situation there are about a million m 3 distributed in about 30 areas (most in Bizkaia) and at the moment there is no reliable technology that allows the total destruction of the waste.

In order not to mortgage the future of these areas, the criterion that is currently being imposed is to confine contaminated land in security deposits. In this respect, we would limit ourselves to remembering the data provided in the previous issue.

While this solution is adequate, its provisional character should not be forgotten, so special emphasis should be placed on the implementation of pre-treatment technologies, that is, separation of waste and land. To measure the success of this effort, two aspects must be taken into account: on the one hand, the separation of the waste would allow its treatment and disposal through the BCD technique and on the other, guaranteeing the complete cleaning of the contaminated soil, would return to the original use.

Meeting these two objectives is the strategic research being carried out within the spri-funded PGTI-95 programme. Two private companies (BCD Process and Geyser-Hpc), the Ihobe Public Society and the Gaiker Research Center collaborate to definitively solve this serious problem.

The objective of the project is to analyze the feasibility of a new pre-treatment and separation technique. The objective of this line of research is the technique of demolition with solvents and it is considered that it can be a suitable solution for this specific problem that we have in the Autonomous Community of the Basque Country. At least the members of this initiative are working on this task, which is expected to be implemented the following year.
Babesleak
Eusko Jaurlaritzako Industria, Merkataritza eta Turismo Saila