Merrett Survey Limited has worked in many different utility industries with topographical surveys and data management that keeps the infrastructure of our country and others running and developing smoothly.
Electricity – We worked for National Grid for 10 years on a framework contract, supporting their in-house Lidar capability with all ground based survey tasks in the UK, USA and elswehere. This included ground control, coordinate transformations, conductor sag measurements, weather data collection, lidar instrument offsets, quality control / ground truthing and scans of transmission routes on the ground where helicopter aerial lidar work was not possible – eg in close proximity to Heathrow airport. Our work in the sector includes:-
Transmission line surveys – on the ground (profile surveys) and in the air (lidar) – with thousands of kilometres of line completed over many years. Our survey work provides clients with the ability to analyse the proximity of foliage to the conductors (infringements), so that power utility companies can plan their vegetation management. This includes finding ‘danger trees’ that could impact on the conductors if they fall. It enables design work on thermal uprating, conductor and insulator replacement, new routes and re-alignments. Our ground based surveys are conducted to meet the standards of the EATS ( Electrical Association Technical Specification ) ESI TS 43-1. Data can be coded and output in formats suitable for input to PLS-CADD.
Tower surveys – We survey towers using reflectorless total stations or laser scanners to enable analysis of verticality, twists and deformation in the steel work. For insulator replacement and condition / asset surveys.
Distribution lines – Previously helicopter based Lidar used to only be considered for transmission line work – due to the expense, but nowadays with improved scan rates distribution lines can be included and even surveyed using area wide methods from fixed wing aircraft. Especially if Geiger lidar is deployed.
Sub-stations – All of the work we have undertaken on many sub-stations is nowadays completed with laser scanning methods. This improves the safety of our personnel as the sites can be surveyed from their periphery. All of the features of a sub station can be modelled from the laser point cloud data including circuit breakers, relays, isolators, transformers, switches and busbar systems plus all visible conductors. We have surveyed sub stations in the open, inside buildings and underground.
Power stations – Laser scanning and 3D modelling of existing stations for modification and improvement works plus monitoring of turbines for movement or misalignment.
Buried cable routes – this has included work for offshore to onshore wind farm projects and intercontinental connector cables.
Clients receiving our power related data include:- National Grid, EDF, SSE, WPD, EON, Scottish Power, RWE Npower, Babcock, Mott MacDonald, Suez, Edra Energy
Gas – We have been involved with pipeline distribution routes for new build pipelines where LNG shipments arriving in UK are connected to the existing natural gas networks.
Telecommunications – Laser scanning of telecom / microwave towers for maintenance and antenna alignment. Buried fibre optic cable route surveys.
Water – Some of our first ever land survey work was for water distribution pipelines and sewage treatment works ( STW ). Our topographical surveys have also been completed for WTW- water treatment works, river and sea outfalls for processed sewage / waste water and intakes for drinking water. Dams and reservoir surveys for condition, flood risk downstream and reservoir capacity tables. This work involves boat based bathymetry for the volumes below water and can include aerial lidar surveys for the above water map of the valley.
3D Bim modelling is becoming increasingly requested for WTW and STW treatment plant sites with complex pipework and plant items fully modelled after laser scanning on site.
UUD / GPR – Underground Utilities Detection – This is an essential part of the development of most sites. Checking for the location and depth of buried services. Merrett Survey Ltd uses a number of trusted partners to provide this service with Merretts managing the work to PAS128 standards. GPR is Ground Penetrating Radar and clients often request a GPR survey meaning they want a full detection survey using a multitude of methods from desktop studies / utility records searches to electromagnetic detection ( CAT and JENNY ) plus the GPR itself.
Laser scanning and modelling
of sub-stations increases safety.
Reservoir surveys – above and below the water
for volumetric capacity computations
Lidar above for high accuracy DTM’s and
multibeam sonar below