LOCATION:   Greenwich

PROJECT TYPE:   Ground investigation

VALUE:   £60K

BACKGROUND

Bugsby’s Reach South is located on the Greenwich peninsula. The site was historically used as a power station, industrial estate/units and fabrication yard.

As part of the Millennium Exhibition, the area was remediated by removal of contaminated hot spots, then re-graded with a temporary capping layer of clean material.

Redevelopment was planned for the site consisting of residential flats together with infrastructure routes and new open spaces.

SCOPE OF WORK

Prior to the undertaking of intrusive works an Unexploded Ordnance (UXO) survey was carried out. In one instance a suspect metal object was discovered. The Harrison Group’s UXO action plan was implemented, all site works ceased and the area was evacuated. In this case the suspect object was not found to be UXO.

British Drilling Association (BDA) guidelines designated the site as ‘YELLOW’, due to the potential contamination still present. It was also positioned within an Inner Groundwater Protection Zone, so clean drilling techniques were adopted to prevent the potential spread of contamination.

Investigative site works lasted two months and included a variety of site investigation techniques:

Cable percussive boreholes – up to 40m in depth
Rotary boreholes – up to 50m in depth

Window sampler boreholes

Trial pits and trenches

In-situ Californian Bearing Ratio (CBR) tests

Gas/ground water & tidal monitoring

The site works proved challenging as shallow obstructions from previous structures and foundations were encountered.

In addition to this a 1m thick band of limestone was present at approximately 22m depth prevented the deep cable percussion boreholes achieving their required depth.

A rotary drilling rig was employed to penetrate this layer in order to confirm the depth of the Thanet Sand formation.
To complete the site works, all trial pits and trenches within hardstanding areas were reinstated with concrete.

OUTCOME

The site works and reporting were successful and further site investigation work has been carried out by the Harrison Group on the Greenwich Peninsula. We also look forward to additional projects as additional plots become available for redevelopment.