Projects
Marine
Lankelma aims to be the world’s leading CPT provider, be it for Land or Marine site investigations. Via strong partnerships Lankelma has been growing rapidly in Marine Site Investigation since 2000.
Lankelma Marine have now carried out projects around the UK and Ireland as well as in the Danish Sector of the North Sea. Harbour site investigations have been carried out in Morocco and Sri Lanka. Tests have been carried out on beaches with crawler rigs, off jack-up platforms with top push cpt and off ships and barges with vibrocores, wireline cpt’s and seabedframes.
Sea Bed Offshore CPT Technologies At Birkenhead
Lankelma Ltd has successfully deployed it’s new 10 Tonne ROSON sea bed penetrometer to determine the depth to the concrete base of the Wallasey Dock Channel, at Tower Road, Birkenhead.
The sea bed penetrometer was lowered to the sea bed using an 80 Tonne crane and was operated remotely from the quayside. An umbilical cable carried the electrical signals to operate the penetrometer motor which in turn operated the pair of friction wheels that advanced the CPT push rods and electric cone into the dock sediments at the specified penetration rate of 2cm per second.
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The investigation comprised 13 CPT’s to a maximum depth of 9.0 metres to provide a geotechnical charaterisation of the dock sediments together with 4 gravity core samples to provide material for a laboratory contamination assessment of the sediments.
The works were successfully completed over a single shift, and provided the Client with significant cost and time advantages over a conventional pontoon and top push CPT alternative.
Cable Route Survey Phase 1, Mediterranean Sea
During the last week of June, Lankelma Marine SI mobilized a sea-floor resistivity, CPT and launch system on board a cable-laying vessel in Denmark.
The vessel set sail for the south of France where it was joined by Lankelma’s offshore survey team for commencement of operations.
Throughout July and August, a Burial Assessment Survey was conducted using data collected from the offshore operations. These data included continuous resistivity traverses between the 10m and 1000m contours off the coast of North Africa and Southern Italy and CPT data from strategic points along the survey route.
Resistivity data were collected using Lankelma’s DSR 3000 bottom towed sledge with a 7-channel streamer configured in an Inverse Schlumberger array. Penetration depths were estimated to be in the order of ª3m with a current of up to 25 amps at 48.5 volts.
CPT data were collected using the Neptune 3000 miniature seabed frame, pushing 2cm2 piezo-cones to a depth of 3m with maximum tip loads of up to 25 MPa.
All equipment was deployed using Lankelma’s own Launch and Recovery System (LARS), which is fully containerized for ease of transport globally.
The LARS comprises a 7m A-frame with launch deck powered from a 7 tonne load sensing umbilical winch with automatic render function. The winch has its own temperature controlled Hydraulic Power Unit that coped well with the almost constant 30-40∞C temperatures on deck.
Substrates varied across the route from very soft sensitive fine grained (foraminiferal oozes) in the deeper water areas to occasionally dense silty sands with some clay overlaying fossil reef material and cemented layers in some shallower areas.
North Sea Report
On the 5th May 2004, Lankelma Seacore Offshore mobilised their WISON APB downhole CPT system on board M.V. Kingfisher at Falmouth docks, in order to undertake a site investigation for Seacore at aproposed Jack-up and storage facility in Dutch sector P10/P11 of the North Sea.
The mobilisation of the WISON APB system with heave-compensated drill spread was completed in 4 days and following dynamic positioning tests, M.V. Kingfisher embarked for Rotterdam.
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The site investigation started on 10th May with a scope of works comprising 18 boreholes to a maximum depth of 65m below sea-bed level (~95m below LAT).
Mud-line CPT’s were used to prove echo sounder readings and the first four continuous PCPT tests were performed to 35m over a 48 hour period in calm weather conditions. Typically, tip loads of 30-40 Mpa were encountered in the shallow holes with loads in excess of 65 Mpa below 40m depth.
Composite sampling/CPT boreholes were completed using the WISON APB’s downhole 1m push sampler giving excellent recovery in all substrates (Holocene sands and Pleistocene alluvial sequences) up to a maximum push of 3 tonnes (the limit of the thin walled sample tubes). This high load is possible due to the use of a sample tube protection system used on the WISON APB. Samples were processed using the on-board laboratory under the ever-wacthfull eye of NGI’s Tom Lunne.
The works were completed without incident on 22nd May and the ship sailed to Bømlo in Norway to De-mob.
Barrow Wind Farm, Cable Route Survey
On the 5th April 2004, LSO mobilised vibrocore and ROSON CPT equipment to Heysham harbour to commence the cable route survey for the proposed wind farm at Barrow. All equipment was loaded on-board the ‘Laura M’, a multi-cat owned and operated by GSS Ltd. of Rhu in Scotland.
After a short period of bad weather, the survey works commenced with the 5m high powered vibrocorer giving good penetration through substrates ranging from very loose silty sands to stiff gravely clays with numerous troublesome cobbles. Recovery from cores was consistently in excess of 90% of penetration with a required level of 75%. In all, some 69m of penetration were achieved giving 57m of core sample for analysis.
CPT operations proved to be more troublesome due to the nature of the cobbles. All tests were performed to a target depth of 5m with a 30kN ROSON seabed frame using 5cm2 and 10cm2 cones with pore pressure measured at the U2 position. Some 67m of testing have given an excellent overview of the area of seabed to be trenched.
The survey area in Morecambe bay is littered with archaeological sites and anomalies and as such, all positions were overlaid on a chart of these sensitive areas. One location was deemed to be unacceptably close to an anomaly to be practical and was therefore moved to a safe distance. Positional data were measured using a Starfix DGPS system giving excellent accuracy in X, Y and Z planes.
Lankelma in North Sea
The King Fisher vessel has been mobilised with Seacore to perform some offshore CPT testing with the A P Van Den Berg down hole CPT system in the Dutch sector of theNorth Sea.
Lankelma Marine completes south coast project
During February 2004, Lankelma Marine was contracted to conduct a site investigation at a major natural harbour on the South coast of England. The harbour area in question was due to be deepened by a programme of dredging from its quay walls to the open sea approximately 3km outside of the harbour entrance to facilitate the movement of large vehicle and freight ferries.
Some 140 vibrocores were scheduled to 6m depth using a high powered electrical system deployed from a crane barge. A spud-leg pontoon towed by the tug Kingston Lacy owned and operated by Jenkins Marine Ltd (Poole) was used for the project. This barge proved to be an excellent platform for coring operations being spacious, stable and manouverable. The barge was positioned using a DGPS system with an antenna on the crane boom for absolute positional accuracy.
Weather conditions for the project were initially very good with very calm seas outside the harbour in the main swash channel allowing excellent positional accuracy (<1m-.0m) and sample recovery. A pod of seven dolphins from the local area headed in to the barge to see what was happening and stayed to play all day.
Inside the harbour entrance, a very strong tidal current (~4knots) has left two areas of Flint cobbles with almost all fines winnowed away. Penetration in this area was expected (by the client) to be poor, however on testing both penetration and recovery were excellent. All cores were sampled at 1.0m depth for Particle Size Distribution analysis to determine suitability of dredged material for beach nourishment and sub-sampling was carried out for contamination testing.
Any material of archaeological significance recovered in the cores (Peat, Wood, etc.) was highlighted to the client for subsequent investigation by the local university. In all, some 800m of core samples were taken from areas of differing substrates including Silts, Sands, Clays and organic material, Gravels and Cobbles. Field works were completed in 10 days (approximately one week ahead of schedule) during 12hr daytime operations including mob and demob of equipment. Digital field logs were available to the client on a daily basis during the survey. The report and laboratory results were issued as draft copies one week after completion.
Proposed Extension to Port of Colombo South Harbour (Sri Lanka)
On the 5th of March 2004, LSO mobilised a CPT crew to Sri Lanka in order to conduct a programme of nearshore testing for Seacore. The proposed project involves a substantial extension to the existing container port at Colombo, the island’s capital.
14 tests to a maximum depth of 11.5m (bedrock) were completed over a period of 8 days from a jack-up platform operated by Seacore. All CPT’s were top-pushed using supportive casing down to mud level. The data returned indicated a sequence of generally soft silty sands and clays overlying a gravely sand (probably weathered Gneiss) overlying very hard or dense material (probably the local bedrock Gneiss). Dissipation testing was performed at discreet levels at numerous locations.
All equipment performed well in temperatures of 40∞C and humidity levels approaching 65%. Testing took place over a 24 hour shift pattern with most production possible during the early hours of the morning to early afternoon.
On-shore winds in the afternoon and evening caused an increase in the sea state preventing movement of the platform between holes.
Harbour investigation
Lankelma has recently completed Cone Penetration Testing, Project Management and professional support to Main Contractor Seacore Limited and subcontractor Lankelma Seacore Offshore for a large ground investigation programme at a major port in South East England.
The Scope of works consisted of 51 top-push onshore and marine PiezoCone Penetration Tests through Hydraulic Fill, Made Ground, Alluvium, the Lambeth Group, Thanet Sands and Upper Chalk to depths of up to 26m.
The marine PCPTs were performed using one of Lankelma’s 20 tonne capacity mobile hydraulic rams mounted within the drilling derrick onboard the Client’s jack-up platform. The system employed a custom made HWY sized riser system between mud and deck levels to enable a significant increase in safe thrust applied to the cone during each test. The increase the potential penetration depths achieved. The onshore PCPTs were performed using Lanklelma’s 23 tonne Track-Truck.
In utilising the advantages of minimal break-out and reinstatement requirements, rapid performance, no-soil arisings, mobile, self contained plant and equipment and high quality data produced, CPTs were ideally suited to the highly active and changing conditions of the Port operations. Similarly, the effects of potential contamination was reduced and the costs associated with Port’s high specification reinstatement costs were significantly lower than conventional investigation techniques.
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Lankelma Challenge
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For
a development in and next to the Thames Lankelma was given the order to
carry out part of the site investigation through cone penetration testing
by WSP environmental Ltd. the consultant for this job. On the land investigation
was carried out by the track truck. Over water was a bigger challenge.
Tests had to be carried out on the dry falling banks. Normally these tests
would be carried out from a jack-up platform but budget restrictions made
this impossible. |
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green field sites brown field sites motorways railways waterways and flood defences marine
research testing in limited spaces restricted access
