Contaminated Soil

For the solution of the problem of soil contamination only limited resources are available. This requires a sober and appropriate use of the resources. The complexity of factors involved necessitates a systematic approach to guarantee decisions to be made in an uniform and transparant way.In the subsequent paper a first sketch is given of a decision model for selecting the final remedial alternative for individual contaminated sites.

Dr. van Spiegel will approach soil protection research by taking Dutch science policy in general as frame of reference. Soil protection research has recently become one of the priority areas of Dutch science policy. An outline of newly developed plans to stimulate and execute this soil protection research program will be presented.Also attention will be paid to the international aspects concerned.

From general surveys of soil science literature a number of concepts of soil become apparent which may be quite different, although they all pertain to the same subject. It usually depends on the viewpoint of the author, mainly determined by his personal scientific interest or background, what is the predominant nature of the concept he uses, e.g. chemical, physical, biological or ecological.

The behaviour and concentrations of the heavy metals Cd, Zn and As in the topsoil of a harbour sludge depot have been modelled with the chemical model CHARON. This model is described briefly. The chemical processes with respect to the heavy metals are treated with some more detail. Two calculations were performed: One with a topsoil of ripening harbour sludge and one with a top-soil of sand. The results of the two calculations show, that the application of a top layer of relatively clean sand does lead to an appreciable lowering of the concentrations of the metals in the pore water, especially in the unsaturated zone. The calculated concentrations of the heavy metals in the unsaturated zone of a harbour sludge topsoil are much higher than in the reduced zone of the profile, whereas the concentrations in the unsaturated zone of sandy topsoil are lower than the concentrations in the reduced zone.This investigation was made on behalf of the Public works department of the municipality of Rotterdam (the Netherlands).

The danger exists during the transportation, storage and production of chemical substances of spillages, due to leaks or faults, when such liquids as fuels or organic solvents are involved, then they would quickly spread and move into the soil. The soil is then to a determined depth contaminated by the substance.

The behaviour of chloroform, 1,1,1-trichloroethane, trichloroethylene, tetrachloroethylene and 1,4-dichlorobenzene in the unsaturated zone of three Dutch soils was studied with large soil columns with a water table at a meter depth. Leaching, volatilization, sorption and degradation were determined during 9 months sprinkling with a solution of these compounds in artificial rain water. In separate continuous-flow degradation experiments with small columns degradation was determined at controlled aerobic and anaerobic conditions. The results show leaching to the water table of all chlorinated aliphatics in all three soils, even in peat soil.Degradation of 1,4-dichlorobenzene was so large that leaching did not take place. Degradation of the chlorinated aliphatics in the continuous- flow degradation experiments varied with compound and soil condition, especially the degree of aerobicity. The large columns showed substantial removal by degradation for all chlorinated aliphatics. Volatilization was a minor removal process in the large columns. Explanations for these observations are presented.

The migration patterns of contaminants leaching from a polluted site into the groundwater are often controlled by a balance between advection and adsorption. This adsorption capacity is associated with relatively impermeable layers of clay and peat. The thicker the layers, the less effective is the adsorption capacity. This is demonstrated by mathematical modelling of the heterogeneous system. It is concluded that models that include even a limited detail of the stratigraphy are much superior to those that don’t.

The ranges of background values of 32 elements in Dutch topsoils (0–10 cm) are presented. For this purpose soil samples were collected in 28 nature reserves. The samples were analysed by means of neutron activation. Considerable differences in element concentrations may occur between the sampled areas. For the majority of the analysed elements a significant linear relationship exists between background values and clay contents. For part of the elements studied, the ranges of background values are in agreement with ranges reported for soils in other countries, but for certain elements distinct differences are observed. The concentrations of some elements in clay soils exceed proposed maximally tolerable concentrations for farming land. With the performed analysis a good insight could be obtained into the background values of many elements in soils. For the elements Cd, Cu, Hg, Ni and Pb another analytical procedure should be used.

In a study of metals in soils, Pb was found to be the least soluble and least plant available element. Cd and Ni were much more soluble and were taken up by plants to a greater extent but the solubility of Cd and Pb varied inversely with soil pH. Cationic forms of Cd predominated in the soil solution. Of the four crops grown on these soils in the greenhouse, cabbage and lettuce had higher metal concentrations in their edible portions than carrot and radish. Uptake was generally greater from inorganically polluted soils. CaCl₂(0.05M) is a useful extractant for predicting the bioavailability of Cd.

The results of site investigations carried out at two sites in Lancashire, England are presented. Both sites comprised virgin glacial deposits, one overlaid with chemical waste, the other with colliery waste. The pattern of groundwater flow was established showing, a water table close to and just above the original ground surface and flowing along the original sloping topography. The results of sulphate content and pH tests in groundwater samples are given and show the effect of increasing concentration of soluble contaminants in the direction of groundwater flow. The results are discussed and comments made on the effects of this phenomenon on the deterioration of concrete placed within the site.

The decomposition of hexadecane (C₁₆H₃₄) in soil is compaired with that of oil in polluted soil at 20°C and at a moisture content of the soil of 60% of the waterholding capacity. Under optimal conditions the rate of transformation of C₁₆H₃₄ to CO₂ appeared to be exponential, indicating a specific growth rate of 0.12 h-1. With increasing concentrations of C₁₆H₃₄ the CO₂ production did never exceed 20 μg CO₂-C.g soil-1.h-1 probably due to oxygen deficiency. The CO₂ evolution of the soil polluted with 3500 μg oil.g soil-1 was stationar from the beginning of the incubation, viz 1.08 and 0.42 μg C.g soil-1.h-1 during the first 25 days and the following period of 55 days, respectively. These low degradation rates are probably due to the characteristics of the oil compounds in the polluted soil.

The transport of spilled oil in the subsoil takes place in both a multiple phase flow (pores filled with water-oil-gas or water-oil) and in a single phase flow (pores entirely filled with water in which hydrocarbons are dissolved).

The awareness that the chemical species play a more important role than the element itself in the transfer along the food chain, has brought about an increasing interest in determining the speciation of trace elements in environmental samples (1–2). We had the opportunity to study in various highly polluted soils the distribution and the availability of trace elements along the profile depth as a function of soil properties. The purpose was to determine in natural conditions the correlations between the migration of heavy metals in a profile, their availability and the chemical and mineralogical composition of the soils.

The simplest means of providing a barrier between toxic materials and potential targets is to cover them with clean fill materials. The protection offered is immediate but it is necessary to question the long-term effectiveness because there are processes which might lead to toxic substances being brought to the surface (this is in addition to deterioration due to erosion, changes in the water table, flooding etc). These processes are: (i) moisture movement upwards due to capillarity of the soil(s) bringing with it water-soluble substances and (ii) uptake of toxic substances by vegetation. The question is not whether such phenomena will occur but rather: (i) whether they occur at a rate and scale that will undo the protection provided by the cover and (ii) how to design a cover system to resist these effects.

In the summer of 1984 the Delft Soil Mechanics Laboratory was contracted by the Hamburg authorities to carry out an investigation of the oil and water movement in a waste disposal site in the south of Hamburg. In the sixties and seventies both municipal and liquid industrial waste in drums and lagoons were disposed at the site (fig. 1 en fig. 2).

The fate of hexachlorobenzene-14C, pentachlorobenzene-14C, l,2,4-trichlorobenzene-14C and benzene-14C in soil was studied in a closed aerated laboratory apparatus, as shown in Fig. 1 1 for seven days. Volatilization, mineralization, conversion in soil, formation of unextractable residues, and uptake by two plant species were determined. For benzene it was shown that mineralization was the main pathway of residue loss from soil, whereas for the chlorinated derivatives volatilization prevailed. Conversion in soil and formation of bound residues decreased with increasing number of chlorine atoms in the molecule (Table 1).

The responsible disposal of highly contaminated dredging spoil from harbours and rivers in industrial areas is a problem of major importance. Economics may preclude detoxifying the spoil whilst planning and political constraints in the densely populated hinterland may make it very difficult to find a suitable and acceptable landfill site.

One of the most important environmental risks of soil contamination in the Netherlands is the threat to groundwater quality. In reviewing the urgency of a contamination case as well as in choosing the most adequate solution to this problem, knowledge of possible transport of contaminants in groundwater is essential. A current approach in estimating spreading of contaminants in groundwater, is multiplication of the average groundwater velocity with the expected length of time passed since contamination started. Such an approach leaves dispersion, e.g. spreading of contaminants as a result of molecular diffusion and transport through a heterogeneous structure, out of consideration, as is retardation, the delay of contaminants as a result of interaction processes with soil material. A considerable amount of the Dutch soil contamination cases deals with hydrophobic organic components such as mineral oils, aromatics, organochloro-pesticides, PCA, PCB, and dioxines.

The herbicide Atrazine is widely used in agriculture, especially in maize. Laboratory studies were carries oud on the behaviour of Atrazine in soil columns. The results of these studies were reported by Loch et al (ref. 1). The soil columns had a length of 110 cm and a diameter of 20 cm. Stainless steel cylinders were filled with two different dutch soil profiles, a “kamppodzol” and a Menkeerd”-soil. The organic matter content in the topsoil of the enkeerd-soil is more than 3 times higher than in the topsoil of the kamppodzol (fig. 1). Adsorption-isotherms were determined in the laboratory by batch shaking experiments (fig. 2).

In the sandy regions in the Netherlands the phosphate (P) applied to the soil in animal slurries constitutes one of the main threats of surface water contamination by diffuse sources. The arrival of P in surface water, either by runoff or by transport in groundwater may cause severe eutrophication. A thorough understanding of the nature of the reaction of P with sandy soil will yield instruments to estimate the capacity of these soils for P-retention and to assess the reversibility of P-fixation. This information may be used for a policy regulating future animal slurries disposal on agricultural land.

The mathematical description of the transport of dissolved contaminants (solutes) in porous media is, in chemical engineering, soil science etc., usually based on solving the transport equation, with the appropriate initial and boundary conditions. For one-dimensional transport in direction z (depth) and neglecting production terms and concentration induced fluid density gradients this equation is: 1$$ \frac{{\partial F}}{{\partial t}} + \theta \frac{{\partial c}}{{\partial t}} = \theta D\frac{{{\partial ^2}c}}{{\partial {z^2}}} - v\theta \frac{{\partial c}}{{\partial z}} $$ be bz (symbols: see appendix). The parameter assessment is generally done by transport experiments in packed soil columns and comparison of breakthrough with results obtained by solving equation (1) (cf Van der Zee et al, this conference). Extrapolation of results found for homogeneous columns to natural systems is often difficult, due to the observed, scale-dependent heterogeneity of naturally occuring porous media (De Haan and Van Riemsdijk, this conference). Depending on the correlation distance of the porous medium at the scale (travel distance) of interest, generally the heterogeneity is accounted for by identifying several sub-domains (mobile/immobile water) or by increasing the value of D in equation (1). However, considering vertical transport in a field, the field-averaged dispersion process for a conservative solute is controlled by the spatial variability of the hydraulic characteristics, and this leads to a non-sigmoid solute front, instead of the sigmoid front usually found if equation (1) is solved (a review is given by Bresler et al., 1982, further reference given there).

Since the primary transport mechanism in a subsurface flow is advection, accurate determination of the velocity of the carrier fluid percolating through the porous medium is extremely important. Computer-based groundwater motion simulators conventionally use pressure as the primary variable, and after the pressure field has been calculated, the velocity is determined by numerical differentiation. It will be shown that this is an unreliable procedure and, for that reason, an approach to direct determination of the velocity field will be presented.

Surface soils in the village of Shipham, UK, (population 1092) contained 2.0–336 (GM 75.2) ppm cadmium whereas soils in a control village contained 0.1–7.6 (GM 0.74) ppm. The health of 548 members of the exposed population was assessed by means of a detailed health inventory, clinical measurements, laboratory studies on blood and urine specimens, and dietary evaluation. The data were compared with a control population matched for age and sex. When corrected for associated variables, the data suggest that the increased cadmium intakes from contaminated soil were not associated with significant health effects.

In the Netherlands an estimated number of 5.000 to 6.000 cases of contaminated soil are known. In several locations the soil contamination has caused health concerns in the involved population. Both the population and the administration want to know if health damage, what type of health damage has been or will be caused and whose health has been or will be damaged.

The effects of five chemicals (pentachlorophenol, 2,4,5-trichlorophenoxyacetic acid, carbendazim, toluene and tetrachloroethylene) on three types of organisms, viz. higher plants, an earthworm (Eisenia foetida), and microorganisms responsible for soil respiration, ammonification and nitrification, have been investigated.At least one of the three types of organisms was very sensitive to at least one of the chemicals.Despite their simplicity, these tests were useful to reveal effects of chemicals on terrestrial organisms.

Three studies into metals in U.K. urban soils are reviewed and metal intake into home-grown vegetable and salad crops discussed. A survey of 5,300 urban gardens in 53 locations in England, Wales and Scotland confirmed widespread metal contamination. Lead in garden soils increased with the age of property. Lead in radish and lettuce increased with soil content, though lead intake into lettuce was shown to be derived more from aerial deposition than from uptake from the soil. Normal washing removed most of the contaminating lead from lettuce. High concentrations of arsenic in garden soils in an old mining area in south-west England were reflected to only a minor degree in the edible tissues of garden crops. Health implications are discussed.

This paper is one in a series of studies concerned with psychological and social problems in residential areas contaminated by chemical wastes. The first aim of this project was the formulation of policy recommendations. Our findings suggest a number of proposals dealing with the apparent conflicts between authorities and residents. In order to alleviate the psychological and social effects of this environmental problem we stress the importance of communication processes and citizen participation in finding a sollution.Presently, we are engaged in extending both the empirical and theoretical base of our recommendations. A follow-up of our survey, to be carried out in the near future, should enable us to develop a model for community response to this type of environmental hazard. The present paper gives a brief overview of our approach by specifying a model of parallel processes dealing with the reactions of the residents to the soil contamination problem.

This paper will afford a simple approach to evaluate the impact of soil contamination with volatile organic chemicals on human health.

Lead is a metal which is toxic to humans: there is no evidence to show that it performs any useful biological function in man. The clinical manifestations of lead poisoning are well known and include anaemia, constipation, colic, vomiting and loss of appetite. The total amount of lead in the body cannot be measured directly, but the lead content of blood can and the values so obtained are taken to represent “body lead”. Blood lead concentrations in excess of 150ug/dl have been observed in adults with no obvious accompanying clinical symptoms but on the other hand symptoms are occasionally encountered with blood lead concentrations below 50ug/dl.

Heavy metal contamination of soils may reduce both yields and the suitability for consumption of crops. The heavy metals uptake from contaminated soils is affected by soil acidity (Albasel, 1985).A field study has been carried out to investigate the relation between cadmium uptake by different crops and the cadmium content in topsoils in two pH-categories (less than 5.0 and more than 5.5.The results of this study have been used to calculate the cadmium intake as it is influenced by consumption of these contaminated crops for top-soils with different cadmium concentrations.The results show that at a concentration of 2.5 mg cadmium per kg soil, and under certain conditions, an exceedance of the limit of the weekly intake of 400 ug cadmium can take place.

The main site being investigated is the Joint Agricultural Land Restoration Experiment at Bush Farm, Essex, England. The Experiment, set up by the Ready Mixed Concrete Group in 1974, demonstrates the feasibility of restoring land back to high quality agriculture once gravel extraction and landfilling with industrial waste has been carried out.

When it became evident that contamination of the soil was a widespread phenomenon, the public authorities decided to initiate an active approach. All administrative levels in the Netherlands participate in this action (1). The central government had and still has the task to define the outlines of the operation and filling in these outlines by an effective instrumentation.

The problems of abandoned sites in the Federal Republic of Germany become more and more important on the stage of environmental policy. The Lander responsible for remedial actions on abandoned sites have itensified their efforts to solve the problem in the past years. At present, each Land procedes differently but in view of the extent of the problem of abandoned sites, the federal and Land authorities have agreed upon a common strategy. The Government contributes towards solving the problems of abandoned sites within the scope of R + D projects. Because of the considerable financial expenses expected for remedial actions on abandoned sites, possibilities to establish a fund for remedial actions are investigated.

All developed countries have land that has become “contaminated” by substances that can present hazards to future users or uses, examples include: sites used for industry, waste disposal, sewage treatment, transport, power generation and the extraction of essential minerals. All these activities have long been carried out in Europe.

The Danish National Agency for Environmental Protection completed in 1982 a nation-wide survey of waste sites. A total of 3115 sites were registered. Chemical wastes are known to be present at 500 of these sites.Therefore the Danish Parliament passed a law in June 1983 to regulate chemical waste sites. The law defines the role of central and local authorities in setting priorities, in initiating site-investigation studies, and in taking remedial action. The law provides a sum of 400 million DKr. to be spent in the 10-year period up to 1993 to clear up these sites.Keynumbers from the 1982 sites survey. 3115 dump and other waste sites through the country were registered of these:

The NATO Committee on Challenges of Modern Society’s Study Group on Contaminated Land recommended further development of treatment methods for the removal or destruction of contaminants. Containment and stabilisation systems were seen as having inherently limited lives and the removal of contaminated soil for redeposition elsewhere is likely to cause problems in the future. The report of the Study Group describes the technologies available for treatment and reclamation of contaminated land and reviews them in relation to the identified need for ‘once and for all time’ solutions. The evaluation of treatments for long-term effectiveness is also discussed.

This paper reviews some of the current techniques used to investigate contaminated soil sites. It covers the areas of remote sensing, soil gas monitoring, groundwater monitoring and soils sampling. Each discussion focuses on current techniques, major problem areas, advantages and disadvantages of the techniques. It is the intent of this paper to provide a basis of understanding and evaluating the other papers presented in the session on site investigation.

The Ministry of Housing, Physical Planning and the Environment commissioned DHV Consulting Engineers to draw up a series of guidelines for sampling and analysis of, soil and groundwater in regard to investigations into soil pollution. In the first phase, methods of sampling and analysis, and the problems, encountered with these methods, were inventoried. In the second phase, provisional guidelines were drawn up, in consultation with numerous experts. The general use of the guidelines in the Netherlands will be to achieve greater uniformity, and thus better quality and reproducibility of analysis-results, in the implementation of investigations into soil contamination which is necessary to achieve more balanced decisions on clean up operations.

In order to determine the severity of soil contamination at former gas-work sites, which are listed in the annual clean-up programmes of the Dutch provinces, investigations are carried out by consulting agencies. The results of several of these investigations show that neither the development of an effective sampling design nor the analysis of the collected information can be considered an easy task. The investigations also indicate that if the results of sampling are poor it is very hard to define adequately the volume of contaminated soil that needs to be removed (and processed).The paper presents a framework for improved sampling. It shows that statistical techniques of sampling and data analysis are valuable tools to estimate the volume of contaminated soil and to indicate whether the concentrations of contaminating substances in the soil exceed the critical standard or not.

Ground water contaminations in the vicinities of several waste sites in Berlin (West) were studied with the aim of developing a step-up investigation procedure, generally applicable to uncontrolled waste sites located on unconsolidated sediments and adequate for screening a large number of sites at feasable costs.As a rule with one observation well an impact of the waste site on the aquifer could be detected. Few analyses allowed a classification of waters: Boron was found to indicate household refuses, calcium and sulphate construction wastes and organic chlorine (determined after charcoal adsorption and combustion) hazardous industrial wastes. Concentration ranges considered typical for different types of contaminations were established.Factor analysis of some thirty parameters analyzed revealed numerous interactions allowing the reduction of analytical efforts e.g. for heavy metals.First steps towards analysis of the numerous organic pollutants encountered in such waters were taken by means of a gas-chromatographic finger print method.From the results a screening procedure was deduced starting at a minimum set of investigations which are to be intensified stepwise at given conditions. This method now is being applied to further sites and the first results are promising.

The paper considers the relative merits of aerial photography and remote sensing by multi-spectral scanner. The authors have experience of MSS data with 2.5 m resolution of a large site with metalliferous contaminants in the Lower Swansea Valley, Wales, flown in 1982 and repeated in 1984.Aerial photography has the benefit of high image quality, stereoscopy, and integration with current cartographic data-bases. Along with the moderate cost of photography goes our familiarity with this type of data, and so there may be little incentive to invest in MSS. However, aerial photography is spectrally limited, and on the whole, the bare surfaces, typical of many contaminated sites, have little variation on images in the visible or near infra-red part of the spectrum. MSS imagery enables us to look into the middle and thermal infra-red. It is apparent that there are more variances here, which provide us with information about both bare and anomalous vegetated surfaces. This discretionary facility, along with the numerical nature of the data, makes the new technology of MSS an attractive proposition.The authors consider two test sites, and show that although there are problems of spatial precision and identification with MSS data, the spectral advantages for site survey, and the monitoring of contaminants, are very considerable.

For detecting and mapping buried waste materials a geophysical survey system has been developed. The general system design, principles of operation, examples of application and the use in combination with other methods for waste site investigation are discussed. Recent developments in signal analysis are presented.

In soil pollution studies soil samples are routinely characterised with regard to soil composition and structure and organoleptic qualities such as colour, odour and fysical appearance.

It is the objective of any investigation of a potentially contaminated site to identify as many as possible of the potential hazards present, in order that appropriate safety precautions may be taken to protect:- (a)environment(b)construction workers(c)construction materials(d)end-occupiers of the site

In order to decide on the appropriate response to a soil pollution incident it is necessary to accurately determine the conditions obtaining in the ground. Several different sorts of information are required. These include the physical and chemical nature and spatial distributions of the contaminants. Furthermore other parameters are needed both at the contaminated site and in the surrounding soils in order to assess the migration potential and thus potential impact on the local and far-field eco-spheres.

In most instances contamination of soil and water results from a polluting source near or at the surface. The extent of a contamination, influenced by percolating water and groundwater flow, has to be established as accurate as possible to allow assessment of its environmental impact and to work out the most appropriate remedial measures.

Volatile organic compounds, if present in ground water or soil, will occupy the interstices or voids in soil. These vapors can be sampled and characterized using a portable gas chromatograph.Soil vapor analysis can be a useful and rapid method for tracing plumes of leaks and spills of many volatile organic compounds (VOC’s). This method is particularly useful for compounds more volatile than xylene (vapor pressure 5mm Hg). Ground water contamination can also be assessed indirectly using this method.Determinations of contaminant concentrations down to the low parts-per-billion can be made with this system. In addition to providing same-day or quicker results, substantially more samples can be analyzed at a much lower cost per sample compared to well drilling and GC/MS analysis. In addition, the system can be shipped virtually anywhere overnight, and can be ready to run within hours of arrival on-site.

In addition to laboratory analysis, rapid on-site analysis might be very useful in investigations of soil contaminations: Rapid monitoring of environmental conditions is necessary for safety measures during site investigation, excavation and remedial actions.In case of excavation, rapid decisions have to be made about the extent to which the soil is contaminated.The extent of the contamination can be determined more accurately in the field, which means better sampling for laboratory analysis and thus lower costs.

The qualitative and quantitative analysis of pollutants in soil and sediments is an expensive and time consuming task since each group of anthropogenic compounds requires an other analytical approach. Therefore some sort of rapid screening of the soil or sediment sample as such for polluting components is very desirable.Curiepoint evaporation and pyrolysis gas chromatography-mass spectrometry have been applied to two “suspicious” samples.The following anthropogenics show up in the gas chromatograms or total ion currents: polycyclic aromatic hydrocarbons, halo-organics, aliphatic hydrocarbons, hetero-aromatics, elementary sulphur, cyanides, pyrolysis products of synthetic polymers, etc.Hence, virtually all organic pollutants and a number of inorganic ones (no heavy metals, however) are revealed within a couple of hours by these techniques, when they are present above the detections limits of the detector(s) used (MS, FID, FPD, ECD).After this screening procedure separate quantitative analyses can be applied to measure the precise amounts of individual components.Details will be published elsewhere.

Irregularly but frequently parts of the floodplain of the River Meuse are inundated and fresh deposits of black reduced river-bed materials mixed with yellowish brown silts from locally eroded soils, are left behind. As a result of waste disposal by metallurgic industries in the Belgian part of the catchment the river muds are highly contaminated with heavy metals. In a matter of weeks the fresh deposits are mixed with the topsoils by ploughing and biological activity. This has caused a considerable increase of the heavy metal concentration of the topsoiIs.The main objective o-f this investigation was to find a method for rapid mapping of areas in the floodplain which are polluted with heavy metals.In a small part of the floodplain with known problems of soil pollution four variables, i.e. inundation frequency, carbonate content of the soil, rate of recent sedimentation and soil development were investigated. These variables were chosen because they are associated with fluviatile processes and their spatial distribution can be determined easily. In this key area a large number of soil samples were taken and subsequently analysed on their content of heavy metals. The concentration of zinc, cadmium, copper, lead, cobalt, nickel and chromium were shown to be positively correlated with inundation frequency, with carbonate content and with the thickness of the layer of sediment deposited after the industrial revolution. Combination of the chosen variables in soil units according to the German system of soi classification explaines over 75% of the variation in heavy metal content of the topsoils.Due to the relation between soil development and fluviatile processes classical pedological fieldtechniques provide a relative cheap and fast method for mapping soil pollution in aquatic environments.

The main purpose of the present study is to develop a field monitoring system for the assessment of the possible impact on the terrestrial entomofauna caused by crop-protection measurements, including the use of insecticides and other pesticides. In the first phase of the study special attention is paid to the epigeal predator arthropod fauna, which in the area concerned mainly consists of carabid beetles and spiders. Particularly this part of the soil fauna is liable to become exposed to above ground applications of pesticides.

The difficulty of conducting bioaccumulation experiments with marine wetland animals in the laboratory is related to the need to establish intertidal conditions. In this study, a simple gravity-fed apparatus was constructed that allowed the comparison of heavy metal, PCB and PAH-uptake by three bioassay species on 2 contaminated substrates. The ribbed mussel (Modiolus demissus), the mud snail (Nassarius obsoletus) and the sandworm (Nereis virens) were selected as bioassay organisms as these species are commonly found in disturbed wetlands and wetlands created with dredged material. Modiolus and Nassarius have not commonly been used as bioassay organisms as has Nereis. The test substrates (contaminated dredged material) came from the Interagency Field Verification of Testing and Predictive Methodologies for Evaluating Dredged Material Disposal Alternatives (Field Verification Program) field site in Bridgeport, CT. The source of the differences in the substrates is not of concern in this study as is demonstrating the feasibility of a simplified intertidal bioassay procedure.

In the case of industrial activities the release of material due to leakage, overfill, spilling etc. is a major source of soil contamination. Leakages from underground storage tanks are important contributors to soil contamination.This paper describes a risk assessment carried out for underground storage tanks for petrol and diesel at filling stations. The outcome of the assessment shows a quantified risk in terms of probabilities of leakages of a certain magnitude. The study compares single- and double-walled tanks fitted with different anti-corrosion systems in various types of soil. The method used for the risk assessment will be further developed into a general procedure to quantify the risk of soil contamination from industrial activities. A method to grade the consequences for the soil — depending on type of soil and properties of the released material — will be included.

In the framework of the Soil Clean-Up (Interim) Act a set of criteria to decide on the necessity of site-examinations or clean-up projects in cases of soil pollution is offered in the Soil Clean-Up Guideline. Three major factors involved are the nature and concentrations of the contaminating substances, the local situation and the use and function of the soil. Criteria for the first factor are worked out in a numerical criteria index (A, B, C values). In the past years the system has proven to work. However, it should be emphasized that in judging a given situation all three factors must be considered. The criteria index is sometimes also used in setting standards for uncontaminated soil. Because of the obvious need for such standards, provisional standards for good soil quality will be developed probably by the end of this year. Definite standards will be developed by a formal system of setting standards for environmental quality which is described in some detail.

Risk assessment of a soil pollution situation plays an important role in the decision whether clean up is necessary.The Dutch government, confronted with thousands of potential polluted locations provided for a test framework enabling easy assessment. Assessment is primarily based on kind and concentration of pollutants found. In several cases where rigorous clean up measures originally were justified on the basis of the test framework, a switch in assessment method can be observed. The focus is much more on direct threat to public health by actual and true exposure to polluting compounds. Such ad hoc scientific justification of policy decisions is undesirable. We therefore propose that the formal testframework should be reshaped, enabling a more differentiated approach in assessing soil pollution cases. This can be achieved by incorporating the notion of “tier testing” in the formal risk assessment method.

Reclamation and redevelopment of contaminated properties in the United States (U.S.) and Europe have been addressed by analyzing what has and is being done at the present time.The U.S Environmental Protection Agency (USEPA) initiated an effort in1983 which susbtantially documented the U.S experience in the area of reclamation and reuse of the landCase studies for nineteen hazardous waste sites in several European countries and twelve sites located in the U.S were selected and examined in detail. These study sites included former coal gasification sites, fertilizer and pesticide manufacturing sites, defence manufactuners and several uncontrolled dump sites. Land reuse focused largely on residential and industrial concerns, but also consisted of govermental, commercial and agricultural facilities.

Physical principles of methods and systems are being described and discussed with respect to their applicability for long term reliable control of different barriers. Emphasis is put on the detection and localization of leakages.Methods are covered which are described in the literature in addition to those which are under development by various institutes or companies. Practical experiences obtained with some systems are being reported.An evalution of the development stage and recommendations for further research are being made.

Good land restoration can only be achieved when there are effective legal, planning and administrative controls operating on the site. This paper takes as its hypothesis that the technical expertise to restore land successfully is available, but it only takes place when the planning controls are sufficiently powerful to compel the operator and the landowner to complete restoration and carry out stringent after care management to maintain the land in productive use. Examining the restoration achievements of seventeen sites in five different counties in England, the author is able to establish how effective different administrative arrangements and legal controls are in achieving land restoration. It is concluded that the most powerful tool for achieving restoration is still to withhold further permission until a good standard of restoration has been achieved on existing working sites.

During many centuries Rotterdam has been an industrialized area. Over the last decades the innercity housing area has been expanded on sites which were formerly used for industrial activities. Redevelopment of industrial sites for housing purposes usually entails the implementation of remedial actions. By now a considerable number of sites are known to be contaminated. The costs of site investigation and redevelopment have been increasing drastically over the past few years. In order to spend the limited funds provided for remedial action in a responsible manner while ensuring an environmentally acceptable use of the sites, Rotterdam has been developing its own way of assessing and handling of soil pollution problems.

Past industrial processes and landfill operations have left a variety of combustible materials on sites required for development. Although tests have been suggested for determining whether the resultant mixtures are combustible none of them is satisfactory: none shows whether the material is sufficiently combustible to burn in an underground fire, presenting hazards to occupants, to buildings and to building services. In order to assess the risk of underground combustion on sites, an analysis has been attempted of the processes governing the initiation and progress of smouldering fires to find which factors are important.Some expected and some suprising results have emerged: they suggest that existing methods for assessing combustibility of soils and the rate at which combustion spreads are inadequate and unexpectedly that underground fires are unlikely to be controlled by restricting the supply of air.

This paper briefly examines the role that can be played by a preliminary investigation of a contaminated site. We suggest that such an investigation, particularly at sites that show moderate to high levels of contamination, can sometimes provide enough information for decisions to be made regarding the suitability of the site for the intended after-use, the reclamation methods likely to achieve this objective, and the most suitable methods for the disposal of excavated material. This may be particularly so where the intended after-use is of comparatively low risk.The paper illustrates this procedures by references to our experinces at old gas works sites, other types of abandoned industrially contaminated land, and at old waste disposal sites.

The Rijnmond Public Authority3 has developed a system for estimating the urgency of site investigation and subsequent sanitation of contaminated soils. The system contains all relevant criteria that determine the possible impact of contaminants in a soil on public health and the environment. An estimate of the urgency can be made at each step of the sanitation programme. The estimate is given as an urgency score. The system has become a necessary and useful instrument for planning the soil sanitation programme and for preparing policy decisions concerning its execution, considering that limited yearly budgets are available for site investigations and sanitations. Two additional applications of the system are of interest. The system helps in predicting the effectiveness of soil sanitation measures and it helps in increasing the efficiency of site investigations.

Methane is not the only major constituent of landfill gas; carbon dioxide, which dominates at the early stages of decomposition, coexists as a major fraction during the anaerobic stages. Many investigations appear to ignore this fact and fail to monitor its presence. The significance of CO₂ can be very considerable since a) it can act as a precursor to methane, b) elevated levels can suggest the oxidation of methane, c) it is highly toxic and asphyxiant (e.g. 3% CO₂ is more hazardous than 3% CH₄) and d) it can seriously affect plant growth.

Holland is situated at the lower course of some important European rivers. The western part of Holland was formed for a greater part from sediment carried along by these rivers. After the construction of dikes, started already in the Middle Ages, the deposition of sediment has been restricted to the riverbeds and the outer marches.

A management strategy for dredged material disposal has been formulated that incorporates a suite of test protocols designed to simulate disposal site environments. In addition, a decisionmaking framework has been developed that interprets test results and determines the need for restrictions on disposal operations. The decisionmaking framework is based on sediment chemistry and biological effects of sediment contaminants as related to a reference site and established criteria. The framework is currently being applied to specific dredging projects and will be refined as experience is obtained through field application.

For quality control of cleaned soil the following points of procedure must be adhered to in the order given: 1.The quality of the bulk of a cleaned soil has to be defined.2.The type of control procedure has to be laid down.3.The demands of cleanness to be met by samples (as opposed to the bulk) have to be specified.4.The instructions for inspection have to be defined.

In clean up actions of contaminated soil occupational hygiene forms an important element in the activities towards the protection of the workers against job related health risks.

The Environmental Response Team (ERT) is the US EPA’s focal point for technical assistance to all EPA offices and Federal/State/Foregin government offices during multimedia emergency episodes involving toxic and hazardous materials. This paper is an overview of the U.S. EPA’s Office of Emergency and Remedial Response safety procedures and operations used at hazardous materials responses as presented in the subject document.

Sites contaminated to less than critical levels can still present hazards, to construction workers in particular, during the installation of infrastructure and other below ground works. The threat from toxic or asphyxiant gases or vapours in deep excavations can be a significant problem. Where the risks from these hazards are unacceptably high, it is necessary to introduce safety procedures that protect worker health and keep risks to a low level. Safe working procedures and safety equipment are best matched, as far as reasonable, with normal engineering practice.This case study outlines the procedures adopted in the redevelopment of part of a former integrated iron and steel works plant. The measures included a ‘permit to work’ system in Restricted Areas; advance gas testing; protective clothing, equipment and facilities; continuous automatic gas monitoring; and a full-time Environmental Safety Officer.

This paper reviewes the various techniques and methods of remedial action at waste disposal sites and contaminated ground. Included are techniques, which are available for use with confidence together with other techniques, which need further development before they can be used in practice. The methods are briefly described, and restrictions and special applications are mentioned. Furthermore a cost relationship for the different techniques is given.

Official concern over the long term hazards involved in reclaiming contaminated land in Britain has gradually declined, and an increase in the number of such reclamations is now occuring.Methods of quantifying soil cover reclamations have been devised and are found useful by the local authority officers who have to evaluate developers’ reclamation proposals.Despite the apparent progress, the lack of technical knowledge on the long-term efficiency of soil cover reclamations remains a worry, as does the lack of information on the effects of many contaminants on human health.

The aim of the investigations done on a waste deposit near Frankfurt a. M., Fed. Rep. of Germany, is to get realistic readings of the quantity of leakage water below a multilayer soil covering system. For this purpose a testing area has been constructed on top of the site, in which the proposed cover was executed. For comparison purposes six different types of soil profiles, each of three layers, are applied. The testfield includes two special designed large-scale lysimeters (each 150m2) for the collection of leachate below the barrier layer in both, an open and a closed system. The water-movement within the covering system is quantified by measurements with neutron moisture probe.

The subject of this paper is a case study of an industrial development on contaminated land, haphazardly filled with domestic and some industrial waste. The first part of the paper traces the history of the area, describes the site investigation, in-situ testing, the methane emission evaluation and the analysis of the likely dangers to the proposed development.In part two the paper discusses the design, measures incorporated into the structures to minimise the risks, outlines the protective action taken during the construction stage and then describes the post-construction performance of the structures and the results of the continuous monitoring of gas emissions for the past four years.

In this paper the possibilities of using isolation technologies as a possible technical response to soil pollution problems is discussed. A design methodology is presented and its limitations at the current state of the art are identified. The major conclusion is that a major design and quality control effort must be associated with the implimentation of this otherwise promising solution.

Four different processes for the thermal decontamination of soil have been developed in The Netherlands. Three processes make use of rotary tube furnaces with different combinations of direct and indirect heating, followed by an incineration of the volatilized products. In the direct heating processes the flames are in direct contact with the contaminated soil, while in the indirect heating process the soil is in contact with the heated wall of the furnace only. The indirect heating process uses an inert gas atmosphere. The fourth process uses a fluidized bed furnace with a temperature of 800–900 C and a freeboard for the incineration of the residual volatilized products.Three processes have been shown to be effective for the decontamination of polluted soils from gaswork sites (polycyclic aromatic hydrocarbons + complex cyanides), while all processes are capable of treating soils contaminated with hydrocarbons (oil type pollution) or aromatic compounds.The treatment of soils contaminated with organochlorine compounds is still under investigation. In view of the danger of the emission of toxic chlorinated dibenzodioxins, special provisions such as high temperature incineration and completely gas tight installations may prove to be necessary.

In a general introduction to extractive methods attention is given to the basic principles, the potential fields of application and the costs of methods for treating contaminated soil.The operational installations for extractive treatment in the Netherlands (Heijmans Milieutechniek BV, HWZ Bodemsanering BV, Bodemsanering Nederland BV and Ecotechniek BV) are described in the second part of the paper.

Micro-organisms have been used since time immemorial in the treatment of wastes, such as organic refuse and domestic and industrial waste waters. From this practice stems the use of microbial techniques for soil decontamination. The present article discusses the state of the art in the Netherlands and touches upon current and future developments in the fields of sludge-farming, land-farming, composting and culturing of specialized micro-organisms.

It is common knowledge that where the cleaning up of contaminated soils is concerned, removal of the hazardous material, i.e. excavation, transport, storage and treatment — if required — has until now mostly been practiced in stationary plants in the Netherlands.

In many cases, the clean-up of contaminated soil generates polluted water. Mostly, the water is polluted to a degree that prohibits discharge of the water, or re-use of the water without treatment. The various options available for the treatment of contaminated ground water, and polluted process water from soil decontamination are discussed. Some field cases of applied water treatment are presented.

In the instance of a contamination of the subsurface with mineral oil, large amounts of hydrocarbons remain in the pore space, even after all oil in-phase has been removed by withdrawal of groundwater. If those residuals include highly water-soluble aromatic compounds, their transport can endanger drinking water supplies.Usually, in addition to the removal of the polluted groundwater, the contaminated soil is replaced by uncontaminated material. A real decontamination, however, should lead to the mineralization of the oil products. A case of such a successful decontamination of an oil-polluted aquifer in an industrial area by microbial degradation in the underground itself is presented here. The life conditions for the bacteria were optimized by adding growth factors such as phosphate and ammonia to the groundwater. Uncontaminated water from a lower aquifer was then injected to protect the unpolluted aquifer by containing the oil-polluted water within the contaminated area. A removal of about 30 tons of mineral oil within 2 years of operation could be achieved by this method. Based on this example, considerations on the decontamination of aquifers polluted with other chemicals are given.

During the inspection of the Georgswerder dumping ground, which was closed in 1979 and has since been substantially recultivated, the highly poisonous Seveso dioxin 2,3,7,8-TCDD was found in the persolation liquid at the end of 1983 and the public was informend. This is the first timethis has occurred in an old German dumping ground. This caused the greatest public interest — not only in Hamburg but far beyond its boundaries — in the environmental problem of practically incalculable dimensions involved in the special refuse from trade and industry which has, in the past, been dumped in what is, at least from today’s point of view, a negligent manner. Apart from the danger potential which it itself represents, dioxin has now acquired the role of signal substance for the variety and quantity of other pollutants which, because of the disposal methods used at the time, have not been destroyed for all time or at least have not been rendered harmless by making them immobile; instead, they gradually appear again as emissions via the ground water, the surface water, the soil and the atmosphere and represent a danger to people and the environment.

This paper has to be seen in context with the paper written by Wolf “The Landfill Hamburg-Georgswerder: Clean-up Concept”. It shows the different steps that resulted in the remedial action concept. The activities that describe the pollution potential of the landfill including the investigations to get information on the groundwater and geological situation are presented. The first remedial actions to improve the emission control and the final clean-up concept are described. The research program that includes long-term monitoring programs in regard to measure the success of the single remedial action steps as well as studies concerning high-temperature incineration and intermedial storage of hazardous waste from the landfill Georgswerder is presented.

Mechanical stabilization methods for improving chemical stability of contaminated dredged material used for upland disposal are presented. Assessments of long term environmental consequences involving effects on heavy metal immobilization, TOC, COD, BOD, anion release, gas production and -composition after addition of lime, calcium carbonate, cement, coal fly ash and gypsum to fine grained Hamburg harbour sediments have been studied. Best results are attained with CaC0₃ due to insitu pH conditions and sufficient buffer capacity, which is of prime importance for metal immobilization and gas production.

The Greater London Council disposes of 3 million tonnes of household waste each year. The Scientific Services Branch is responsible for advising on control measures at new landfill sites and on remedial measures at disused landfill sites to alleviate the problems caused by landfill gas. Case histories are discussed. The Scientific Services Branch advises on the necessary remedial measures to allow building development on contaminated land in inner London. Much of the redevelopment of London Docklands is taking place on land affected by methane gas derived from river silt deposits. The method of site investigation used to assess the potential methane problem is described, as are various methane venting techniques.

Many of the common contaminants occurring in land polluted by industrial waste such as gas and steelworks sites, are potential substrates for microorganisms. Removal of such contaminants may be effected by a strategy of (i) isolating indigenous microbes capable of their decomposition, growing them in large numbers, and reinoculating them into the soil; and (ii) manipulating the physicochemical characteristics of the soil to favour the proliferation of pollutant-degrading organisms.

In the Netherlands, approx. 5,000 cases of soil pollution have been revealed during the past few years. In a number of cases, houses were built on polluted soil.

A waste site in Northern Germany was investigated by remote sensing, rapid on-site analysis and chemical analysis. A very narrow groundwater path heavily contaminated with chlorinated hydrocarbons caused by oil waste was identified.In-situ cleaning was proposed in 3 steps: removal of the mobile oil phase, chemical remobi1isation of residual oil and stimulation of the observed anaerobic biodegradation of chlorinated hydrocarbons.

Occidental Chemical Company operated a fertilizers and pesticides plant in the San Joaquin Valley of California. This plant began operations in 1953 and came into national prominence in 1977 following discovery that a substantial proportion of the pesticide workers were sterile, presumably from exposure to a nematocide, Dibromochloropropane (DBCP). The US Environmental Protection Agency and State of California investigated the Company’s operations and determined there had been adverse environmental effects. This resulted in a 1979 lawsuit and, on February 6, 1981, a consent decree was lodged with the Court which established a framework for necessary studies and remedies. These studies resulted in the excavation and disposal of considerable amounts of pesticide — contaminated soil. Cleaning up contaminated groundwater is being accomplished with a groundwater extraction system followed by an activated carbon treatment system, with subsequent injection of treated water into an underlying, unusable aquifer, 300–500 feet below grade. This system was installed in the summer of 1982 and, to date (August 1985), over 700 million gallons of contaminated groundwater have been successfully extracted and then treated and injected.

In the Netherlands it is becoming more and more common for clean-up projects for contaminated soil sites to include treatment of the groundwater.In this article seven case studies are presented to illustrate Dutch experience gained over the last few years in the operation of groundwater treatment techniques and plants. Various treatment techniques, dependent ons the type(s) of contaminant, are discussed. Conclusions are drawn as to their fesaibility and the management of the projects.

An inventory of data on groundwater pollution at abandoned gaswork sites and of recent experiences with clean-up planning and activities has revealed uncertainties concerning possibilities, environmental effects, and costs of groundwater treatment. In this paper the topics of a study are presented, in which treatment systems have been selected for different levels of pollution, treatment efficiencies and flows for short term, long term and permanent operation. Treatment costs and some environmental aspects are discussed. A possible strategy for decisions on discharge of (treated) groundwater is given.

One of the major cases of soil contamination in The Netherlands is presented: the site of a coal tar processing chemical industry and its surroundings. The environmental contamination, with PAH’s in particular, includes soil, shallow groundwater, the upper aquifer, surface water, vegetation as well as sediments. Approach and results of field and chemical investigations are presented. Special attention is directed towards the criteria for selecting priority sites and the method referred to as scenario evaluation to select remedial measures.

Slurry walls surrounding contaminated areas are important remedial measures for cleaning up improper hazardous waste sites. A comprehensive description of slurry wall application, configuration and construction was made by US EPA /1/. According to US EPA, slurry walls should have the following properties: low water permeability, resistance to hydraulic pressure and chemical attack. Our paper deals with an additional demand on slurry trench materials: they should exhibit high specific retardation of the movement of dissolved contaminants by sorption or irreversible chemical fixation.

An important option for the succesful management of localised soil contamination and of waste disposal sites is their isolation from the surrounding geosphere by vertical cut-off walls. In order to reduce the leakage of contaminated groundwater into the surroundings special attention has to be given to the soil investigation of the site, the material choice of the isolating system and the construction technique.

A scheme of contaminant transport through a vertical barrier is shown in fig. 1.

Many suggestions have been discussed for remedying hazardous waste. The Environment Control Authorities in the Federal Republic of Germany are favourising the method of a long-acting safeguard by means of allside encapsulation. Complete encapsulation of hazardous waste is defined as its total embedding in the soil. This can only prove to be efficient, if the materials used are resistant to aggresive substances and are thus almost permanently impermeable.

The principle purpose is to avoid any contamination of the subsoil by leakage of waste. The proposed structure is sufficiently flexible to follow differential settlements without loosing its watertightness. Repairs can be done if necessary. This substructure mainly consists of three elements, i.e. the bearing vault-elements, the hexagonal cup-shaped supports with a connection to the drainage system arranged in an equidistant triangular grid, and the semi-angular joint-elements covering the open joints between the vault-elements. This system/consisting only of three basic elements, is highly suitable for prefabrication and offers the advantage of rapid and economic construction (see fig.1, 2, 4).

The basic idea of the proposed concept is a waste disposal facility, designed as an above ground building, which allows the storage of hazardous waste independent from impermeable soil conditions. The building is therefore elevated with its base well above groundwaterlevel and contains several chambers, surrounded and seperated by concrete walls, which provide for the stability to the waste disposal. The cells offer the possibility of seperating different materials.

Per year 32,000 m3 of fly ash originating from the incineration of municipal refuse in Rotterdam has to be disposed of. The fly ash is contaminated by heavy metals and organic compounds. The desigh of the disposal site with a capacity of 350,000 m3 has been based upon studies of the impact on the environment, especially with regard to the contamination of soil and groundwaterlevel.

The thermal cleaning of soil contaminated with HCH was investigated on a laboratory scale in a tubular oven. Satisfactory cleaning results are obtained, except for clay-peat, at temperatures > 350 °C and a residence time of the soil in the heated zone > 30 min. Depending on the type of soil, part of the HCH decomposes into varying amounts of pentachlorocyclohexene, trichlorobenzenes, dichlorobenzenes and chlorobenzene.Humic soils contaminated with HCH produce several chlorinated phenols, wellknown precursors of chlorinated dioxins, under the conditions of thermal cleaning.

This poster presents the first tentative results of a one year project in the field of soil reclamation. The aim of the project was to evaluate the economic possibilities of a new biodegradation technique. Because of the disadvantages of the widely used biodegradation method, landfarming, a new method is developed, a bioreactor system. The major advantage of working in a reactor is the possibility to control the conditions. Ploughing in landfarming can’t prevent the presence of gradients in oxygen and for example nitrogen. For this reason the degradation process in a bioreactor is faster.

The municipality of Tilburg had planned to build houses on the site of the former gasworks in the center of Tilburg.

Basingstoke was until recently, a medium size market town in Hampshire, approximately 50 miles south west of London (a 19th century town map is included in the presentation).

Pyrite slag is a residue originating from earlier sulfuric acid production, based on the mineral pyrite (FeS₂). The residue of several plants in Germany and other West-European countries was transported to the “Duisburger Kupferhütte” for extraction of valuable metals and finally used as an iron ore in the Ruhr area. As a result of new blast furnace techniques pyrite slag became unsuitable for this purpose and a solid waste was born, that found its way in several directions.

The outer dike area along the Diemerzeedijk bordering the IJmeer (former IJsselmeer), east of Amsterdam, was intensively utilized as a dumping area for debris, fly ash and household wastes during 1960–1980. On a separate 1 ha large location at the south-eastern border of the disposal area, large scale chemical waste dumpings also took place (see map). All of the wastes were in liquid form, mostly consisting of organic solvents, aqueous solutions of metal salts and miscellaneous. Virtually all wastes were packed in steel drums of conventional 200 1 size. Huge piles of these drums containing several hundreds of tons were regularly set on fire. As a result more or less incomplete combustion of the wastes occurred, leading to enormous clouds of soot and black smoke during the burning process and an incineration residue of unburnt and partly burnt chemicals of considerable diversity. Since dumpings and incineration took place on unprotected surface area, wash-out of chemicals to both groundwater and nearby surface water was to be expected. An inventory of the wastes showed that they could be divided into 7 distinct categories, as summarized in table 1.

During many centuries Rotterdam has been an industrialized area. Over the last decades the inner city has been expanded on sites which were formerly used for industrial activities. Redevelopment of industrial sites for housing purposes usually entails the implementation of remedial actions. One of these sites is situated in the old DELFSHAVEN-district, particularly the WAALDIJK-surroundings (see figure 1).

In de midst of the “Noordhollands Slagen Landscape” three small islands were decontaminated in 1984 and 1985, islands that were contaminated by chemical waste from the Zaanse industry.

In order to find solutions for the current yearly discharge of 2x106 tons of fosfogypsum in surface water studies were started to evaluate the technical, economical and environmental aspects of the preparation of pellets from fosfogypsum, coal fly ash and cement. This contribution deals with the environmental aspects of this operation. The study has shown that the release of Cd, Cu and Zn from these pellets is substantially reduced in comparison with fosfogypsum. SO₄2-, F and Mo release on the other hand limit to a certain extent for their application. Appropriate fields of utilization from an environmental point of view are embankment and structural fill.