At the above location a 150mm diameter gas pipeline crosses the water course. The water course at this point is an average 22m in width with a max depth at time of inspection of 2.5m.
The gas pipeline running below the riverbed has from recent surveys been found to be exposed over a distance of 6.0m. The level of exposure ranges from crown of pipe up to between 8-5 O’clock positions.
Northern Divers were requested by to carry out remedial works at the above location, the proposed were to place protection over the exposed pipe section in the river.
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View of concrete cobble mat.
Works were as follows:-
Prepare riverbed either side of gas pipeline, diver by hand, levelling stone.
Place sandbags around exposed section & over top of gas pipeline. (1No bag thickness).
Place 6-9 No max concrete cobble mats in line over exposed section of gas pipeline. (See photo for the mats).
Blend mats into bed up & down stream & either end of exposure.
Pin mats into bed utilising stainless steel pins.
Because of the proximity of the live gas pipeline, a permit system was thoroughly adhered-to and a Competent Person was on-site throughout the works.
The site was on private land with no public access.
The works were carried out as a diving operation all works were carried out under the HSE ACOP regulations L104 (second edition).
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View of mat just being laid over gas line, rock guard pipe matting secured to the underside of the mat.
Prior to the start of works extensive ecological surveys have been conducted, identifying wildlife & environmental issues.
The works have been planned so as to impose minimal impact on the surroundings, the works were conducted during a time that inflicts minimal impact on wildlife. Once the works are completed & the river banks have established growth it will promote & encourage new habitats for wildlife.
Any waste materials were taken off-site and disposed-of in accordance with the Site Waste Management Plan.
The landowner & local fishing club were updated throughout the project and all interested parties kept informed of progress at all times.
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View of the diver over line of gas pipeline
200mm gas pipeline, NL0014 Reading Branch, crosses a watercourse, The Cut, just north of the M4 near Maidenhead.
Inspections had revealed that, because of scour partly caused by upstream vegetation and debris, a section of the riverbank had eroded to the point where the pipe’s swan-neck, previously within the bank, had become exposed, putting the pipeline at risk of damage.
Northern Divers were employed through an existing National Framework Contract to undertake the survey, design and repair of the eroded bank in order to maintain protection to the pipeline.
