![]() ![]() ![]() Plot is known as a function plot or graph of a function.Ternary plots are commonly used to allow interpretation of ground gas monitoring results.Another feature leverages DeltaGraph’s ability to store multiple pages of charts in a single document it lets you display your graphs sequentially in slide-show format.There are various ways of plotting data in ternary graphs. This paper explains two different approaches that can be used and the implications that need to be considered when interpreting the data. It also provides advice on using ternary plots to help characterise the ground gas regime and risk where only low concentrations of carbon dioxide and/or methane have been recorded in monitoring wells without elevated flow rates. Ternary plots are commonly used to plot ground gas monitoring results (Teasdale et al 20). They are also used to assess the flammability of methane and air mixtures (Figure 1) and to assess geological and hydrogeological data.Ī ternary plot is a triangular plot of three variables which must sum to a constant value, e.g. ![]() In most cases the ratios of the three variables are plotted as points on an equilateral triangle (West, 1982). There are two ways of plotting data in ternary graphs. This paper explains each of the approaches that are used and the implications that need to be considered when interpreting the data. Ternary plots allow trends in gas composition to be identified and this can help to identify the potential source of the ground gas. It should not be used in isolation of other data nor without a robust conceptual site model.īS8485: 2015 and previous assessment methods (Wilson and Card, 1999, Boyle and Witherington, 2007 and Wilson et al, 2007) require that where the carbon dioxide concentration exceeds 5% consideration is given to increasing a site classification from Characteristic Situation 1 up to Characteristic Situation 2. A ternary plot can help to assess gas monitoring data to identify if there is an elevated risk and whether the classification should be increased.įigure 1 Flammability diagram for methane Carbon dioxide is widely present in natural soils at concentrations up to 21% and this often leads to uncertainty about whether to increase the classification. Place the label alongside the axis zero line (Figure 2b).Place the axis label at the apex of the triangle at the point where the axis value is 100 (Figure 2a).There are different ways of plotting the axis labels on ternary plots. Place the label alongside the axis values (Figure 2c).This can be confusing at first glance because the labels are not alongside the axis values. Whichever approach is taken it is useful to colour the axis labels, values and the gridlines so it is clear which axis relates to which gridlines. This makes it much easier for users to read the data from the graph.Īn example of how to read the data from a graph is shown in Figure 3.įigure 2 Different methods of axes labelling for ternary plotsįigure 3 Reading data from a ternary plotĪs discussed in the introduction the three variables being plotted on a ternary diagram must sum to a constant value. For ground or landfill gas assessment when considering the permanent gases methane, carbon dioxide, oxygen and nitrogen, this is normally 100%. The contribution from any trace gases at ppm level is ignored (e.g. Plot methane, carbon dioxide and oxygen + nitrogen.There are two ways to plot the data to achieve the requirement that all the values add to a constant value: However, these trace components should be considered separately as they can give useful information regarding the source of the main permanent gases. ![]()
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