Developing 3D geological and hydrogeological models for the low level waste repository site, west Cumbria, UK

• Published in: Quarterly journal of engineering geology and hydrogeology 2021-05, Vol.54 (2)
• Main Authors: Coleman, C. G, Grimoldi, E, Woollard, H, Holton, D, Shevelan, John
• Format: Article
• Language: English
• Subjects: applied (geophysical surveys & methods); ArcGIS; Boreholes; characterization; coastal environment; cone penetration tests; Cumbria England; data bases; data processing; Datasets; Drilling; England; Environmental assessment; Environmental geology; Europe; geographic information systems; Geology; Geomorphology; geophysical methods; Geophysics; Glacial geology; Great Britain; ground water; Groundwater; Groundwater flow; Historic buildings & sites; Historic sites; Hydrogeological models; Hydrogeology; Hydrologic data; hydrology; information systems; Lake ice; Lakes; laser methods; lidar methods; Low level; low-level waste; mapping; penetration tests; Pleistocene; Quaternary; Repositories; risk assessment; safety; site exploration; Three dimensional models; United Kingdom; waste disposal; water quality; Western Europe
• ISSN: 1470-9236; 2041-4803
• DOI: 10.1144/qjegh2020-026

This case study presents the recent development of new 3D geological models for the Low Level Waste Repository in Cumbria for the purposes of hydrogeological modelling, through the review of historical and new datasets. The site is located in an area of complex Late Pleistocene glacial geology and geomorphology which control near-surface groundwater movement, but which benefits from extensive historical site characterisation data. The work emphasises the value of a quality review of existing borehole records, drilling techniques and supplementary information to build a predictive geological model. Integration of different data has proved crucial to achieve understanding of the ground conditions, characterised by complex Quaternary sequences, and the depositional processes responsible for their formation. The updated geological interpretation suggests that the Low Level Waste Repository is located on a former ice-dammed lake plain. This is contrary to the previous interpretation of multiple, extensive, till units in the area. While the permeabilities may be relatively similar in both interpretations, the extents may be different. Understanding the depositional processes and extent and hydrogeological characteristics of the deposits is key to developing a hydrogeological model that is appropriate for use to assess the environmental safety of the site now and into the future.