Utility Pipeline Pre & Post Construction Land Drainage
Case study
Utility Pipeline Pre & Post Construction Land Drainage
Pre and post construction land drainage works for the Doggerbank Windfarm onshore civils works and utility pipeline easement.
Scope
A joint venture partnership between SSE Renewables, looking after the construction phase, and Equinor taking the lead on the operation phase, is tasked with developing the Doggerbank Windfarm project.
Over three phases Doggerbank A,B and C, located between 130Km and 190Km offshore, will become the world’s largest offshore wind farm, generating 3.6GW of energy.
Making landfall at Ulrome, the high voltage pipeline cuts an easement across 44Km of multiple landowners property to the converter station at Creyke Beck.
Sweeting Bros Ltd were pleased to be appointed by Jones Bros Ltd to provide bespoke trenching and land drainage expertise for 50,000m Pre-Construction Land Drainage of varying diameters, 75,000m Post Construction Land Drainage, multiple road crossings to highway specifications, investigation and archaeological works, sub-soil reinstatement works, evidential documentation for design consultants, ditch crossings and reinstatement works, staff compliance with EUSR & Streetworks Accreditation, and 500,000 man hours without Lost Time Incidents.
Key Aspects
PRE-CONSTRUCTION PHASE
Initially existing land drainage plans are developed by the design consultant to ascertain locations across multiple landowners property affected. These are developed to understand the extent of works necessary to cut off drainage crossing the easement and to install new carrier drains and outfalls along the lengths of the proposed pipeline.
Investigations are also undertaken alongside archaeological works to expose anomalies and protect existing services, utilities and buried artefacts.
Sweeting Bros Ltd have invested in 5 bespoke GPS enabled trenching machines which automatically cut a slice into the ground, lay pipe and backfill with stone using geo-documentation software to accurately position both depth and location. All junctions are photographed and added to the geo-positioning log.
This information is then documented on as-built drawings with the consultant.
POST CONSTRUCTION PHASE
On completion of the high voltage cabling works, reinstatement commences to provide land drainage along the length of the easement, with typically 3 lengths of 80mm diameter pipe installed using the trencher. Again all geo-documented with regard to depth and location.
Sub-soiling works are undertaken to remove compaction, with topsoil being reinstated.
As-built Drainage Drawings
As built drawings documenting existing land drainage connected into new 160mm diameter carrier main along the length of the easement.
Challenges
Health & Safety
All workings were carried out compliantly under CDM 2015 protocols require comprehensive assessment of all risks and method statements to minimise risks for all work elements.
Sweeting Bros Ltd are unique in that we have invested in mountain rescue sleds and equipment to facilitate patient evacuation in the event of an accident. Our work is often in secluded, inaccessible areas with very poor ground conditions.
Buried Services/Overhead Powerlines/Unexploded Ordnance
Certain areas were prevalent to bombing in WWII. Surveys are necessary to understand any risks associated with excavating or trenching.
Biosecurity
Inter-site moves across properties often requires biosecurity and environmental protocols to minimise transfer of contaminants or invasive species such as black grass. This can require washing down time for machinery prior to moving to be included as part of programming works.
Working with Water
Working in or around water poses hazards for employees arising from the natural environment. The presence of vermin and exposure to leptospirosis twinned with the possibility of drowning, all add to the normal risks involving accidents concerning machinery and moving parts.
Works taking place in/around live watercourses also pose problems arising from adverse weather and increased rainfall leading to poor ground conditions, waterlogging and flooding. It was necessary to monitor and adjust programmes to accommodate and minimise risks. Pumping out of accumulating / rising ground water on certain projects/locations may be necessary to ensure safe working conditions.
Cooperation
As with any large project where multiple contractors, designers or works are taking place, co-operation is key factor in success. Sweeting Bros Ltd are adept at managing/working with multi-agency stakeholders such as land-owners, IDB’s, main contractors, Environment Agency and Clients Representatives.
Planning a land drainage project?
Speak to Sweeting Bros about land drainage for agricultural, utility and infrastructure projects.