The GEVAL evaluation grid - A method for evaluating the quality level of agricultural spreading of sewage sludge

Abstract

Agricultural spreading is, currently, the main way municipal sewage sludge is eliminated in France. However, quality of the spreading operation remains very variable. Thus, we propose an evaluation chart of the quality of the spreading operation; this chart, named GEVAL, is built in order to standardize the quality assessment of agricultural spreading of municipal sewage sludge. This chart takes into account all the steps of the sludge production and agricultural utilisation process including storage. At each step the process quality is characterized by various criteria, which were selected to be simple enough to minimize the risk of subjectivity of the controller. These criteria are designed so that they can be adapted to the whole of sewage purification plants in a department or a region. Thus this evaluation chart should allow not only self evaluation of quality in one plant of a given area but also departmental or regional assessments. The present version of the chart cannot be regarded as final: it still has to be tested in France at a large scale, to improve its accuracy.