The Laing O’Rourke and J Murphy & Sons joint venture commissioned ADAS Environment to identify the presence and extent of terrestrial invasive non-native species (INNS) within the 34km2 HS2 Phase 1 Area North limits of deviation.
- HS2 is an emotive project with some landowners reluctant to provide access.
- Invasive species are most easily identified in the summer when the plants are mature and in flower, however award of the work in late September meant that the surveys couldn’t start until October.
One of our unique selling points is our ability through RSK Orbital, to perform aerial surveys, which reduce the need for land access. After considering options we determined that the most efficient and accurate approach was to have an invasive weeds specialist carrying out real-time identification from a helicopter. The 34km2 was surveyed in three days by helicopter fitted with a high-resolution, gyro-stabalised camera. The invasive weed specialist directed a camera operator to zoom in as required to allow him to review the high-definition video footage in real time for positive or probable species identification.
On-foot surveys will check the location mapped from the air and survey all woodlands, where the canopy may have obscured invasive species and watercourses.
Fifty four locations of positive or probable invasive non-native species (INNS) identifications (approximately 83 ha) were found during aerial surveying. A further 58 woodlands (approximately 119 ha) and 63 watercourses (approximately 36 ha) will also be mapped out manually. In total, 238 ha, just 7% of the total area, needs to be surveyed on foot. This massive reduction in on-foot access will help to avoid confrontation and reduce the time needed for negotiating access and on-the-ground surveying.
The joint venture is currently seeking and access. The majority of the ground-truthing surveying is likely to take place in summer 2018 when the species will again be visible.
High definition aerial surveying has reduced the requirement for on-foot surveying to only 7% of the total area, avoiding confrontation and limiting the time needed to negotiating land access.