7. Access possible for walks so why is investigation limited? Is a landslide only going to affect the school? [RW]
Given the nature of the site, several limitations were imposed on the investigation. Limited access to the site was primarily due to constraints posed by dense vegetation and steeply sloping ground. Works were only carried out where safe access and working areas could be achieved. Vegetation clearance was undertaken to gain access to previously inaccessible areas however, a large proportion of the study area remains covered with vegetation and limited, to no investigation was undertaken in these areas.
Given the difficult nature of the site, several investigation options were reviewed taking into consideration many factors including but not limited to, Health and Safety, the effectiveness of the method and costs.
Intrusive investigation could only be undertaken in areas of cleared vegetation and where it was safe to do so. Geophysical survey was implemented to supplement the Ground Model.
Assessments have been undertaken on the available information considering the site constraints. Modelling has been careful to acknowledge uncertainties linked to the constraints.
Based on conditions at the time of the assessment, the consequences to the school of a landslide were significantly different than for residential houses. Based on observations there is likely to be a lower volume of material on the flanks of the quarry spoil tip and the direction of travel of a landslide from the quarry spoil tip would likely be perpendicular to the slope contours, i.e., towards the school – please refer to figures 12-14.
Monitoring shows downward movement of the Quarry Spoil Tip (towards the school). Our previous assessment suggested that the Quarry Spoil Tip was Marginally Stable, i.e., that it was likely to fail at some time in response to destabilising forced reaching a certain level of activity. The information from the inclinometers suggest that the Quarry Spoil Tip is moving and is Actively Unstable, i.e., destabilising forces are producing continuous or intermittent movements.