Tree establishment and growth at Pitsea landfill site,Essex, U.K.

Investigations at an 11-year-old landfill site have shown that soil moisture was positively, and soil oxygen was negatively correlated with temperature and concentration of soil methane generated by decomposition of the underlying landfill materials. A thin (0.2 m) cover of soil-forming material over the landfill showed acute oxygen deficiency and high temperatures. The high moisture content of this cover was probably caused by upward movement of water from within the landfill across a temperature gradient. Nearly all the trees of five species on the thinnest (0.2 m) cover died, but survival and growth was markedly improved on 1.5 m additional clay cover over the landfill. This material prevented landfill gas contamination, and also contained sufficient plant-available soil moisture to negate the large soil moisture deficits the area experiences in most summers. The evidence presented shows that landfill sites are dynamic in the distribution of landfill temperature and gas emissions and the planning of tree planting schemes should take this into account.     

Chemical Variation and Catchment Characteristics in High Altitude Lochs in Scotland,U.K.

Previous research has established clear relationshipsbetween the chemical composition of surface waters andthe nature of their contributing catchments. Theserelationships are particularly strong when broadenvironmental gradients are considered. However, forfreshwaters at higher altitudes, some of the catchmentprocesses that mediate chemical composition are lessinfluential than those at lower altitudes. The waterchemistry of 85 upland lochs in Scotland, U.K. is examinedto assess differences in chemical composition along arelatively short altitude gradient. Principal componentsanalysis identifies the main gradients of variationwithin the dataset. A series of digital datasets is usedto characterise the catchments according to a range ofattributes including soils and landcover. Multivariatestatistical analysis is undertaken to examine the extentto which the catchment attributes can explain variationin surface water chemistry in upland systems. Theseempirical relationships may be used in the development ofregionalisation procedures, which will allow upscaling ofknowledge from individual sites to regions.     

Design and operation of leachate control measures at compton bassett landfill site,Wiltshire, U.K.

This paper describes the conversion of a difficult landfill, inherited by Wiltshire County Council during local government re-organization in 1974, into a high-standard landfill, providing containment of wastes. It can now provide the capacity to continue to receive wastes for at least the next 30 or 40 years. An essential feature of these works is an on-site, automated leachate treatment plant. The design philosophy and difficulties encountered during the commissioning of the plant are described in this paper. Initial difficulties in treating large quantities of methanogenic leachate from saturated areas of waste have been overcome by a novel scheme, whereby a high-strength organic waste stream from a local jam factory is blended with the influent leachate streams for optimum treatment conditions.     

Incineration risk perceptions and public concern: Experience in the U.K. improving risk communication

Siting decisions for hazardous waste incineration continue to be delayed and impeded by adverse public reaction. Improved public relations and education of the public about risks are the favoured approaches amongst many experts and the industry for allaying public concerns. This paper identifies the limited potential for such strategies and advocates instead attention to the whole risk management system for hazardous waste siting decisions. The paper's conclusions and recommendations arise from an examination of the nature, sources and impact of public concerns about incineration in the U.K.