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Tender Value: £0.5M
Client: Babcock Engineering Services


Rotary Drillholes

Advanced at various locations within the base, this included through the base of the existing dock facilities to characterise the underlying rock succession.


Diamond Coreholes

Drilled to characterise the integrity of the dock concrete structure, as well as for pilot holes for follow-on investigative drilling.


Cable Boreholes

This included a significant number outside the base within the river environment using a floating pontoon platform approach.


Security Arrangements

All site personnel had to obtain security clearance to work within the Naval Base.

Allied Exploration & Geotechnics Ltd. (AEG) carried out two phases of investigation work for Babcock Engineering Services in connection with the refurbishment and upgrade of the naval shipyard facility. The first phase involved over-water (near shore) and on-land investigation using cable percussion and rotary coring techniques, as well as down-hole geophysical surveying in order to assess the condition of the bedrock.

This was followed up by a second investigation to provide data on the materials comprising the floor construction of No. 1 dock using a combination of large diameter diamond coring with rotary drilling continuation into the underlying rock strata. Forty-eight 150mm diameter diamond coreholes were performed using our Excalibur Vulcan diamond rig in order to obtain representative samples of the dock floor concrete materials. These pilot holes were followed by rotary drilling utilising a 100mm down-the-hole hammer for openhole sections, and a 412” barrel and an impregnated drilling bit (mist flush) where coring was specified. Schmidt Rebound Hammer testing was used to assess concrete strength in other areas of the dock.

Both contracts were intensive and needed to be carefully planned, especially as ship repair operations were being undertaken at the same time. Logistically the company’s dedicated site team performed admirably to secure another successful outcome. All site operatives were vetted by the MOD prior to commencing work within the naval base.