Application of ground-penetrating radar to investigate the effects of badger setts on slope stability at St Asaph Bypass, North Wales

Abstract

At the St Asaph Bypass, surface cracking developed along the crest of a modern highway cutting, above a cluster of badger setts excavated in the sandy soils of the cutting slope. This prompted concerns about the extent of the underlying tunnel systems and the possible existence of deep cavities lacking surface expression that might cause a potential slope instability problem. The full threat posed to the integrity of the cutting and to the safety of road users remained uncertain. In addition, intrusive investigations were deemed inappropriate and a non-invasive solution to the problem was required. Ground-penetrating radar was used along a 50 m stretch of the cutting to determine the full extent of the badger setts beneath the surface. The geophysical survey identified 324 m of tunnels and demonstrated that the tunnel network was generally shallow ( c. 0–2 m). Pronounced radar reflections characteristic of air voids were identified in the data and interpreted as the badgers’ access tunnels and living and nursery chambers whereas the more subdued features were interpreted as collapsed and abandoned diggings. This case history illustrates the benefits of using ground-penetrating radar to provide an understanding of slope stability and local ground conditions in areas of environmental sensitivity when non-intrusive investigations are required to provide reassurances in relation to public safety.

Wildlife crime: The application of forensic geoscience to assist with criminal investigations

“…Although every case study will be unique as discussed by others (see [30][31]), the research presented here has important implications for the use of geoscience techniques to assist forensic practitioners with wildlife crime investigations as [29] [32][33][34]37]), with others showing both similar frequencies [37] and up to 900 MHz frequency antenna to be deployed [41], but here, the combination of the two different techniques also importantly allowed the quantification of the spatial location of filled entrances and the amount of tunnel infill. This geoscientific information, combined with the lack of slurry elsewhere on the surface, made the alternative hypothesis of an accidental deposition of slurry on the surface by a perpetrator(s) extremely unlikely.…”

“…From previously published research on badger sett and entrance surveys (see [37]) and on similar forensic cases [21,23,24], mid-range GPR antennae frequency were deemed optimal.…”

“…Geoscientific site investigation methods for search vary depending upon the specific case, site, and numerous other factors that are reviewed elsewhere [30][31]. 6 Ground Penetrating Radar (GPR) has been evidenced to be able to both detect and map animal burrows, from gophers [32][33], European rabbits [34], moles [35], wombats [36] to badgers [37]. Water penetrating radar (WPR) had also been successfully deployed within a water-filled ditch in a rural area to locate illegally-dumped badger remains [31].…”

Using near-surface geophysics to assist with the management of southern hairy-nosed wombats (Lasiorhinus latifrons) in South Australia

“…The first published study was done in 1996 to map rabbit warrens on the Adelaide plains of South Australia (Stott, 1996). Subsequently, GPR has been used to investigate badgers (Meles meles) in Wales (Nichol et al, 2003), gopher tortoises (Gopherus polyphemus) in Florida (Kinlaw et al, 2007), and pocket gophers in Texas (Geomys personatus maritimus) (Cortez et al, 2013).…”

Buried Tracks: Ichnological Applications of High-Frequency Georadar

“…However, georadar imaging can also be extended to substrates that lack ferrimagnetic or paramagnetic minerals. For example, sufficient dielectric contrast exists between sediment and air (e.g., unfilled burrows; Stott, 1996;Nichol et al, 2003;Kinlaw et al, 2007), sediment and rock, sand and mud (Di Prinzio et al, 2010), and even between wet/damp and dry sand.…”