Atmospheric Dispersion Modelling
Dispersion modelling is required for most EP/PPC applications. Computer models are able to estimate the environmental concentrations of emissions from many types of source (eg stacks, roads, landfill sites, accidental releases). All modelling of this nature has a degree of uncertainty; ADM is able to offer considerable experience in both modelling and assessment of the uncertainties of modelling predictions. The figure shows an example of the output from a dispersion model in terms of impact to ground level concentrations resulting from a new waste-to-energy plant, including the effects of nearby buildings, terrain and the time varying nature of emissions thoughout the year.
For some of our clients computer based dispersion models cannot provide the answer or the degree of certainty required. In these circumstances physical modelling in a wind tunnel can provide a solution. One of ADM's senior staff, David Harvey, worked at BMT Fluid Mechanics for 5 years undertaking many wind tunnel studies and so he has a thorough knowledge of wind tunnel techniques.
As part of the review of major industry the Environment Agency occasionally require the impact of a source of air pollution or several plants to be determined in terms of the deposition of sulphur and nitrogen oxides. This deposition is harmful in some places where the ecosystems are sensitive. In order to determine the impact it is necessary to map the impacts onto the various ecosystems and compare the existing deposition plus the contribution from the source to what the ecosystem can tolerate (ie the critical load). It is then possible to produce maps of the areas where critical loads are exceeded and to investigate the effects of various emissions control strategies in relation to this. ADM undertook, in collaboration with Foster Wheeler, a detailed study into sulphur dioxide abatement at two large power stations in the north of England for Edison First Power Limited.