1. If there is a danger to the school, surely there is a danger to other properties? [SH]
Based on conditions at the time of the assessment, the consequences to the school of a landslide are 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.
There is insufficient data to undertake a quantified risk assessment for the wider village area (all areas excluding the school). Consequently, a qualitative assessment based on AGS (2007) was undertaken based on a degree of belief approach.
Probabilities of detachment and runout considered suggest a likelihood of impact on residential properties of:
- >10-4e. “unlikely” for slopes of 27° or more,
- >10-5e. “rare” for slopes of 27°-23°
- >10-6e. “barely credible” for slopes of <23°
The consequences of impact were considered to be moderate damage to some of the structure i.e., medium consequence. This suggests a “low” to “very low” risk to property from this hazard, depending on the slope angle. This is “usually acceptable to regulators” (AGS, 2007).
It is likely that current landowners will be responsible for ongoing maintenance and stability matters, including risks presented to downslope people, property, and infrastructure.