Option 3 Methodology Sample Clauses

Option 3 Methodology. This option builds on the results of Option 2 and using additional subsurface data derived from borehole logs (see Error! Reference source not found.). This supplementary information provides an evidence base to support the presence or absence of sand and gravel resources. An example borehole log is shown in Figure 11. From analysing these logs the thickness of each horizon can be established and in some cases information on the composition may be included. Figure 11: Example of borehole log illustrating thickness and composition of individual horizons. Where boreholes show no evidence of sand and gravel or it is mixed with too much clay\fines (see Figure 6) they can be used with expert knowledge to redefine the extent of the resource areas through the exclusion of areas not recognised as a resource. Figure 12a) illustrates the area selected based exclusively on geological description; whilst Figure 12b) indicates the revisions made to the extent of the resource based on the evidence gained from the borehole logs. A further development of this option would be the use of the borehole information to model individual horizons from the borehole data. This is a migration from a simple two dimensional representation of the data to two and a half or simple three dimensional interpretations of the data. This would allow simple volumetric calculations to be carried out using surface area and thickness of resource derived from the borehole log data. Figure 12: Rationalisation of sand and gravel resources from borehole information. Although Option 3 is unlikely to be suitable for a cross Europe approach, it has been successfully applied at a national scale in the Netherlands as illustrated in Figure 13. The maps and website (xxxx://xxx.xxxxxxxxxxxxxxxxx.xx/delfstof/zandgrindviewer.htm) provide an indication of thickness and extent estimates of sand and gravel by both total quantity and extractable volume based on detailed borehole and grading information. The methodology requires a significant amount of detailed borehole data and knowledge on how to interpret the data to generate realistic volume calculations. This option is more appropriate at a more local scale. Further details of the application and development of 3D models is described in Task 3.4 Technical requirements for 3D. Figure 13: Sand and Gravel resource maps and thickness estimations for the Netherlands.