Hastings Pier Restoration – New Visitor Centre Ground Investigation

http://www.southerntesting.co.uk/blog/hastings-pier-restoration-new-visitor-centre-ground-investigation/

In August 2014 Southern Testing were awarded the ground investigation Contract for the new Visitor Centre on Hastings Pier, in East Sussex.

The purpose of the ground investigation was to determine and characterise the underlying ground conditions to provide geotechnical parameters for design of the piled foundations supporting the new Visitor Centre in the middle of the pier.

Southern Testing were first approached by Hastings Pier Charity in early 2014 as to the feasibility of completing the borehole drilling from the existing pier deck at a point approximately 10m above bed level.  Various options were considered and a site visit was also undertaken to assess structural and loading issues relating to access and necessary strengthening works before the drilling could start.

The north end of the Pier (onshore) is crossed by the White Rock Fault which runs NE -SW. The NW downthrown side of the fault shows the site to be underlain by the Tunbridge Wells Sand Formation composed of mudstones, silts, sandstones and ironstones, which is in turn underlain by Wadhurst Clay Formation composed of shales and mudstones with subordinate beds of silt, sandstone, limestone and ironstone. However, the geology to the southeast side of the fault, which includes the entire overwater section of the pier is not recorded on the BGS sheet.

The geology recorded immediately southeast of the fault and to the east of the site of the pier showed the area to be underlain by the Ashdown Formation which are composed of fine grained, silty sandstones and siltstones with shale and mudstone. With no further information available it was thought likely that the underwater geology of the site was comparable to the geology of the land to the east, and probably overlain with sand and gravel associated with sea bed and beach processes.

Borehole drilling was completed overwater from the newly strengthened pier deck (at a height of approximately 10m above bed level)

Symmetrix overburden drilling methods were used initially to form the borehole in the superficial materials. Rotary core drilling methods were used to form the remainder of the borehole and to obtain core samples in the underlying bedrock.

Recovered cores were logged and photographed on site and then transported to our in-house laboratory for detailed testing and analysis.