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Avfallsklassning av förorenad jord – Slump eller vetenskap? Utvärdering av olika provtagningsstrategier för avfallsklassning inom förorenade områden

Larsson, Isabelle LU (2012) MVEM12 20121
Studies in Environmental Science
Abstract
A great part of the soil remediation projects in Sweden today are being carried out on heterogeneous contaminated areas where for example industrial activities have been going on for a long time. In many cases waste from the industrial processes have been dumped or spread out on the property, and there is no pattern in the occurrence of contaminants. The distribution of the concentration of the contaminants is skewed and approximately log normal in the majority of the contaminated areas.

In Sweden today there is no general well established methodology or sampling strategy for taking representative samples in heterogeneous contaminated areas. One of the most common sampling strategies is a systematic strategy within grids where each grid... (More)
A great part of the soil remediation projects in Sweden today are being carried out on heterogeneous contaminated areas where for example industrial activities have been going on for a long time. In many cases waste from the industrial processes have been dumped or spread out on the property, and there is no pattern in the occurrence of contaminants. The distribution of the concentration of the contaminants is skewed and approximately log normal in the majority of the contaminated areas.

In Sweden today there is no general well established methodology or sampling strategy for taking representative samples in heterogeneous contaminated areas. One of the most common sampling strategies is a systematic strategy within grids where each grid has the area of 20*20 m. in each grid, typically five samples are taken, one from each corner and one from the centre of the grid. The samples are analyzed as discrete samples or as composited samples. This sampling strategy is claimed to result in a good coverage of the contaminants in the area, and decisions about the area are made based on the results from the analysis of the samples. However, several sources claim that just a few (here five) samples is not enough to acquire results representative for the contaminated area.

Recently (February 2012), a report was published in the USA about a sampling strategy that, if used correctly, will generate highly representative results from sampling within heterogeneous contaminated areas. The strategy is called Incremental Sampling Methodology – ISM, and is based on a great number of discrete samples put together to a composite sample. This procedure is performed at least three times (minimum of three replicates) and will give highly representative results of the situation of contamination.

In this master thesis, four sampling strategies have been tested in practice within a 20*20 m square area. The purpose was to validate the sampling strategies ability to provide results that are representative of the mean concentrations of contaminants in the area. One of the strategies that was tested is based on the ISM but was not performed completely “by the book”. The commonly used systematic strategy within grids was also tested. In the property where the sampling took place there has been a match factory and several mechanical workshops. It is a typically heterogeneous contaminated area that will be remediated before exploitation with residences and office buildings. The results from the testing of the sampling strategies have been compared to a very thoroughly sampling within the 20*20 m grid that is representing the true mean concentration of the contaminants. Sampling with just a few discrete samples turned out to frequently lead to misjudgement of the mean concentration of contaminants. The strategy based on ISM turned out to be the most confident strategy; it gave in the best estimates of the true mean concentration of contaminants in the grid.

The fact that the majority of the soil sampling today is carried out with methods that result in misleading results can cause severe consequences. The incorrect methods can lead to areas being classified as clean although they are contaminated, or being classified as contaminated although they are clean. This means a risk to people and the environment and can lead to extensive consequences from costs of remediation after buildings have been put up or other safety arrangements. Areas that are classified as contaminated although they are clean lead to greater costs for landfilling or waste treatment. This is an economic waste but is also a waste of resources since the highly qualified landfills in Sweden are filled up with clean material. (Less)
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author
Larsson, Isabelle LU
supervisor
organization
course
MVEM12 20121
year
type
H2 - Master's Degree (Two Years)
subject
language
Swedish
id
3408872
date added to LUP
2013-01-25 14:00:31
date last changed
2013-01-25 14:00:31
@misc{3408872,
  abstract     = {A great part of the soil remediation projects in Sweden today are being carried out on heterogeneous contaminated areas where for example industrial activities have been going on for a long time. In many cases waste from the industrial processes have been dumped or spread out on the property, and there is no pattern in the occurrence of contaminants. The distribution of the concentration of the contaminants is skewed and approximately log normal in the majority of the contaminated areas.

In Sweden today there is no general well established methodology or sampling strategy for taking representative samples in heterogeneous contaminated areas. One of the most common sampling strategies is a systematic strategy within grids where each grid has the area of 20*20 m. in each grid, typically five samples are taken, one from each corner and one from the centre of the grid. The samples are analyzed as discrete samples or as composited samples. This sampling strategy is claimed to result in a good coverage of the contaminants in the area, and decisions about the area are made based on the results from the analysis of the samples. However, several sources claim that just a few (here five) samples is not enough to acquire results representative for the contaminated area.

Recently (February 2012), a report was published in the USA about a sampling strategy that, if used correctly, will generate highly representative results from sampling within heterogeneous contaminated areas. The strategy is called Incremental Sampling Methodology – ISM, and is based on a great number of discrete samples put together to a composite sample. This procedure is performed at least three times (minimum of three replicates) and will give highly representative results of the situation of contamination.

In this master thesis, four sampling strategies have been tested in practice within a 20*20 m square area. The purpose was to validate the sampling strategies ability to provide results that are representative of the mean concentrations of contaminants in the area. One of the strategies that was tested is based on the ISM but was not performed completely “by the book”. The commonly used systematic strategy within grids was also tested. In the property where the sampling took place there has been a match factory and several mechanical workshops. It is a typically heterogeneous contaminated area that will be remediated before exploitation with residences and office buildings. The results from the testing of the sampling strategies have been compared to a very thoroughly sampling within the 20*20 m grid that is representing the true mean concentration of the contaminants. Sampling with just a few discrete samples turned out to frequently lead to misjudgement of the mean concentration of contaminants. The strategy based on ISM turned out to be the most confident strategy; it gave in the best estimates of the true mean concentration of contaminants in the grid.

The fact that the majority of the soil sampling today is carried out with methods that result in misleading results can cause severe consequences. The incorrect methods can lead to areas being classified as clean although they are contaminated, or being classified as contaminated although they are clean. This means a risk to people and the environment and can lead to extensive consequences from costs of remediation after buildings have been put up or other safety arrangements. Areas that are classified as contaminated although they are clean lead to greater costs for landfilling or waste treatment. This is an economic waste but is also a waste of resources since the highly qualified landfills in Sweden are filled up with clean material.},
  author       = {Larsson, Isabelle},
  language     = {swe},
  note         = {Student Paper},
  title        = {Avfallsklassning av förorenad jord – Slump eller vetenskap? Utvärdering av olika provtagningsstrategier för avfallsklassning inom förorenade områden},
  year         = {2012},
}