Near Shore Drilling

Deep boreholes to investigate and assess ground strata adjacent to the shoreline.

In order to develop a reliable and relevant ground model it is essential that the distribution, depth and nature of the ground strata beneath a project development area are known.  On many coastal and marine projects effective investigation of the ground beneath the shallow water zone, adjacent to the shoreline, can be particularly problematical. 

The nearshore zone is generally considered to be that area underwater with a maximum water depth of around 18m to 20m.  In the nearshore zone specialist jackup platforms and other static access platforms can be used to place drilling equipment above sea level such that seabed and deeper ground conditions can be investigated.  In greater water depths floating platforms and investigation vessels must be used as jackup equipment generally becomes impracticable. 

The drilling of exploration boreholes is one of the most detailed and thorough means of investigating the ground strata, potentially to significant depth, and, when used in combination with other complimentary investigation techniques, can provide the necessary data to help the project team assess geotechnical risk, define an appropriate ground model, determine relevant design parameters and develop optimised solutions. 

Some of the key advantages of nearshore borehole drilling are that samples are obtained from significant depth for visual inspection and testing, overlying competent material can be penetrated to assess the nature of underlying less competent strata and a number of different tests can be conducted in the borehole to help assess the in-situ properties of the ground.  The major limitation of borehole exploration, and particularly nearshore overwater investigation, is general the relatively high costs for each borehole.  To ensure that the borehole work is cost effective it is essential that the location, depth and testing regime are well planed and optimised to meet project requirements and anticipated ground conditions.  

The CMW team combines nearshore drilling experience from both Engineering Geologists and Geotechnical Engineers to plan, scope, execute and log overwater borehole drilling and in-situ testing work to help maximise the quality of the data obtained and ensure relevance to project outcomes.  As CMW has extensive experience in complimentary ground investigation techniques, such as CPT probes, geophysics, grab sampling and vibro-driver sample recovery, we can scope relevant investigation programmes to ensure maximum cost effectiveness of the nearshore borehole drilling work. 

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