Osborne/SCA Group
Services Supplied on this Project:
- Geotechnical Ground Investigation.
- Groundwater Monitoring
Key Considerations:
- Health and safety plans
- Public safety
- Stakeholder communications
- Utility scanning
- Working on Slopes
The Project
Geo-Environmental Services Limited was instructed by SCA Group on behalf of Osbourne to undertake a Geotechnical Assessment at Swale Cutting near to New Milton in Hampshire. The line between Sway and New Milton had accumulated significant delay hours due to flooding of the track caused by a nearby watercourse discharging into the cutting that this site is located in. The watercourse system needed altering in order to prevent the flooding of tracks causing further delays. As such, the objectives were to obtain information on ground conditions to aid the design of the proposed upgrade to the drainage adjacent to the cutting. Rotary drilling equipment had originally been suggested, but following a conversation with our Head of Rail, Road and Utilities, this was changed to cable percussion drilling equipment as it was considered to be more appropriate for the anticipated ground conditions and a far more cost effective solution.
Services Provided
- Provision of a Construction Phase Plan and RAMS pack specific to the proposed investigation and attendance of a PTS qualified Geo-Environmental Engineer.
- Construction of 1 No. cable percussion borehole to a depth of 15.0m bgl together with in-situ testing & sampling at regular intervals. These were undertaken during mid-week day shifts.
- Undertaking two falling head soakage tests (one within the superficial River Terrace Deposits and one within the Headon Beds and Osborne Beds).
- The installation of a full depth ground-water monitoring standpipe. This would be monitored at the time of installation and on two further occasions at specified intervals.
- Waste Acceptance Criteria (WAC) testing on a single representative sample form shallow depth.
- Provision of a Factual Report detailing the encountered ground and groundwater conditions and the results of in-situ and laboratory base testing. The report was delivered in electronic format only.
Benefits
One of the key difficulties on this site was the extremely boggy nature of the ground conditions, following heavy rain prior to attending site. On inspection of the site it was deemed that it would be unsafe to continue without mitigating this risk. Bog mats were brought allowing the drilling crew to get safely into position.
There was also an issue with the sub-contractor who was initially brought in to drill the borehole, however, because Geo-Environmental has a very robust and well vetted supply chain we were able to use another supplier, resolving this problem within hours of the issue occurring and the project was delivered on time and budget.