To give an idea of the range of projects in which we were involved in 2006, below is an outline of some of our work.

1. Site Ops.

SWG now operate the following drilling capabilities:

• Two cable percussion rigs
• Four rotary rigs capable of open holing, coring, odex and augering
• A mini-rig for restricted access sites
• Various concrete and asphalt coring systems
• A tracked window sample and dynamic probing rig

2. Contamination Investigations

The range of sites that SWG have investigated recently include former filling stations, chemical factories, tanneries, airfields, railway premises, gasworks, textile works and numerous miscellaneous industrial sites. With the range of small intrusive rigs at our disposal, we are able to investigate potentially contaminated sites quickly, safely and efficiently and with the minimum of disruption to a sites ongoing
operations.

3. Landslip at Honiton

SWG have just completed the investigation and design of remedial works for a large landslip in the Greensand near Honiton.
The landslide caused temporary blockage of a stream course with associated knock-on effects downstream.
The investigation comprised detailed trial pitting to expose and sample the slip plane, rotary drilling and laboratory analysis including shear box testing.
From the investigation a detailed geological model was set up.
Stability analyses were then undertaken using Slope/W and Slide software, and a scheme of sheet piling designed to stabilise the hillside.
The sheet-piled retaining wall was designed using the Oasys soil structure interaction computer program ‘FREW’.

4. New Devon Gas Pipeline

In the past twelve months SWG have completed the ground investigation for over 20 miles of new pipeline for Laing O’Rourke, working with Transco.

The site stretched from Ottery St. Mary in East Devon, to Kenn Village on the west side of the River Exe.

Exploratory holes were focused around stream and road crossings, and comprised sixty trial pits and 30 boreholes.

5. Railway Networking

SWG have recently completed over a dozen ground investigations for railway projects, generally under rigorous time constraints, and sometimes nocturnal shift working. The works have formed part of
NR’s Cornwall Feasibility Studies.

Sites investigated have included Victorian viaducts, potentially contaminated engine sheds, bridges and tunnels requiring upgrading,
and potentially unstable cut slopes and retaining walls.

6. Clyst Honiton By-Pass

SWG have recently completed the ground investigation for a new by-pass to the south of Exeter International Airport.
The site works involved the sinking of six boreholes and the excavation of twenty trial pits with in-situ CBR and soakaway testing.

Reporting included the design of cuttings, embankments, foundations and road pavements, and a full geo-environmental assessment.

7. Former Chemical Works, North Somerset

SWG have continued the geotechnical re-development of a former chemical works for the construction of 120 new homes in north Somerset, throughout 2006. The project has involved four phases of investigation, the design of a 200m long reinforced fill river slope (see photograph), 250,000m3 of earthworks, and raft, piled and spread foundations for houses.

Settlement of the fill soils is being monitored by digital surveying techniques to check theoretical consolidation predictions, and to confirm whether raft foundations can be used as opposed to more expensive piling.

The scheme has been ongoing since May 2004, and is due for completion in 2008.

8. New Quarry Processing Plant, Cornwall

This year has seen the completion of a comprehensive ground investigation, including interpretative reporting and preliminary slope design for a new quarry processing plant in Cornwall.

The scheme involved the creation of a 15m high sub-vertical face in
weathered rock with a 10m high reinforced fill embankment above.

The investigation optimised the use of state of the art down-the-hole logging techniques, which were carried out by specialist sub-contractor
Robertsons Geologging.

Optical logging techniques gave ‘virtual’ 3-dimensional cores of 100%
recovery from which discontinuity data for kinematic stability analyses
could be undertaken. The technique permits logging of open drilled holes, obviating the need for expensive and unreliable traditional coring in difficult ground conditions.

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