Author: ch4Adminnew

We recently had the opportunity to deliver on a month-long ground penetrating radar survey of utilities for a renewable energy solar farm project in Exeter.

Ground-penetrating radar (GPR) is a geophysical technique that uses radar pulses to image the subsurface, and is often used by underground surveyors to identify buried objects, such as pipes, cables, and archaeological artifacts.

As this renewables project involves a lot of ground mount piles to be installed as the project progressed; our first week was spent establishing Primary Controls and producing accurate topographical surveys of each field so as to ensure that any anomalies picked up would be accurately positioned to Ordnance Survey OSGB36 Grid.

Once complete, our topographical survey was followed by the establishment of multiple local grids in order to segment the fields for GPR scanning. This allowed us to maintain an accurate and precise GPR survey of any below ground utilities discovered. These grids were marked out using flags, measuring tapes, and a bit of Pythagoras theorem, for our series of 200m by 15m grids; and were marked at 1m intervals using matching flags at each end.

We were then able to scan the fields by moving the GPR antenna along the survey lines marked. We made sure to maintain a consistent speed and direction, adjusting the height of the antenna when required to maintain a consistent depth of penetration. Throughout this project we were faced with both extreme weather and ground condition challenges, both of these factors can often influence the accuracy of the data being scanned. On this project, our risk management procedures were very helpful because we were able to both manually operate the ground penetrating radar and still use alternative methods to minimise manual effort; meaning that we were able to still deliver our work on time.

As soon as we finished a particular GPR survey grid as marked on the field, we uploaded the data to the cloud where one of our colleagues in London were able to process our scans in near real-time. Processing the data enabled our colleagues back in the office to create an image of the subsurface and involved filtering and stacking the data to remove noise and enhance the signal. During our survey we managed to discover a number of land drains, water pipes and manholes as important information to pass on to the client in order to help design the solar panels around these existing services.

Overall, this was a complex and time-consuming project, but with careful planning and the right equipment, we were able to provide valuable information about the subsurface to our client in good time.

Written by Engin Kaya
Edited by Olivia

For more about our GPR scanning services feel free to call us on 02072780778 where a member of our team will be happy to help.

Here at SESE we offer a range of site setting out services from installing Primary Survey Controls to Setting Out brickwork. All work is carried out by an experienced setting out surveyor or setting out engineer; and we use only the latest Robotic Leica and Trimble Total Stations with high specification, ensuring accurate and efficient work. All our team have access to and are proficient in AutoCAD, again ensuring accurate and efficient work. This summer our site engineers have been busy on a wide range of projects from setting-out extensions on small domestic projects to setting-out gridlines on the 30th floor of large multi-million-pound projects. We have been working closely with a range of civil engineering contractors on several large hi-rise projects on West India Dock Road, Mount Anvil Site and Nine Elms Lane. Due to the prefabricated nature of a lot of building sites a very high degree of accuracy is required during construction so our setting out is required to be extremely precise. This year alone we have come close to setting out 100 floors on these projects all accurately set out and with our experts on hand to solve any dimensional issues promptly to allow construction to continue. Our engineers have also been streamlining our processes often setting out many floors in one day. Another project we have provided setting out services for is a 5-story development in Wheatstone which includes 20 luxury flats and 2 penthouses. SESE have been assisting on this build since the beginning of the job when we provided the initial Topographical Survey and installed the Primary Survey Controls. As the building has progressed, we have provided other setting out services including setting out for gridlines, setting out for brickwork and setting out for the SFS and window openings. We recently handed over the top floor to the construction team providing a full compliment of gridlines and the perimeter wall face including openings. Height datums have also been provided as the building has progressed. Excellent levels of accuracy have been achieved by SESE throughout the project allowing the client to be confident of the position of each element of the building, rather than relying too much on each of the individual sub-contractors. Running alongside these larger projects we have also completed many single day projects for smaller developers which would include setting out gridlines, setting out foundations or setting out corners of blockwork. Alongside any other requirements such as retaining walls, drainage and site boundaries. Our projects can be positioned using GPS coordinates or offset distances from nearby structures. Contracting SESE to provide the setting out guarantees the setting out of the building is positioned with millimetre accuracy. Our engineers are always happy to go above and beyond the requirements and will communicate clearly with your site teams to help ensure there is no confusion. We can also provide as-set-out drawings of the work completed if required.
Alongside our busy setting out team we also offer many other services including measured building surveys, topographical surveys, as-built surveys and GPR surveys. We also specialise in the structural movement monitoring of buildings, providing a no fuss service with results you can rely on.

Site engineering surveyors are one of the very first people a property developer would engage when considering any form of construction or refurbishment of their property or land.

It is often the developers’ architect that first engages a site engineering surveyor for the initial measured building survey or topographical land survey, depending on whether it is for a new build development or for the refurbishment of an existing development that the property owner has in mind.

Once the land or property has been measured accurately, and both the structural engineer and architect have added their respective load bearing and visual design elements; it is then back up to the site engineering surveyors to start with the precise construction setting out services required at each phase of the project. More about this can be found in our article on the importance of a professional setting out engineer.

If as a developer, architect or contractor you are at the stage where your precise building position is a must and are not in need of construction setting out services on site every single day; our in-house site engineers can be booked either over the phone or online at any time of day, avoiding many of the problems associated with booking ad hoc site engineering services. Whether setting out foundations like ground mount pile positions, setting out steel for the superstructure, or setting out brickwork for curtain walls; if you are looking for a site engineer UK wide simply click HERE to get an instant online quote or call us now on 02072780778 where a member of our team is ready to help.

One of the questions our monitoring surveyors often get asked at SESE Ltd is whether structural movement is the same as subsidence? The simple answer to this is no; however, I’m sure, since you have opened this article, you would like to know why.

Subsidence is caused by the settlement of a grounds structure, whereas structural movement can be caused by a whole host of anomalies, including the settlement of ground strata.

Ground settlement is the downward movement of the ground, generally caused by changes to stresses levels in the strata and can either be natural or manmade. It is often caused by water (or the lack thereof). For example, a natural cause for those of us living near the coast may be a stratum layer with a high sand content; this layer could be meters deep, and still be getting slowly washed away by the incoming and outgoing tide. Another example could be an inland property built on strata with a high London Clay content, as the clay swells and shrinks through the seasons, the structure built on it may experience subsidence if its foundations are insufficient to handle the vertical stress applied.

CORE have written an interesting research paper on the shrinking and swelling effects of London.

I have written more on below ground voids and how SESE can help detect them in our April GPR Survey article on How much should a GPR Survey cost. For our ground penetrating radar survey cost for detecting voids, tree roots and utility pipes you can also click HERE to go straight to our FREE GPR Quoting App.

As alluded to above, whether a building is experiencing structural movement or subsidence, the most important thing is to monitor any building movement as soon as possible to help formulate a plan for remedial works.

Why carry out structural movement monitoring

As it increasingly becomes part of a developer’s construction phase plan, structural movement monitoring will not only help determine whether any building movement is due to subsidence or another form of structural movement, it also helps determine the extent of any damage being caused.

By implementing what we call trigger levels, a weekly monitoring report can help determine when different forms of remedial action need to be taken.

For example, building movement monitoring is often specified by party wall surveyors with weekly structural monitoring survey reports as a minimum prerequisite for major construction works, especially those taking place in close proximity to a neighbouring property or a major infrastructure.

The exercise of monitoring building movement is a preventative measure; and the building movement monitoring systems used at South East Site Engineers are designed to be non-intrusive unless specified otherwise by a party wall surveyor or structural engineer.

Our range of high-tech instruments, mean we rarely need to physically touch a building to detect movement to +/- 0.002m, which helps determine whether any potential structural movement is due to local construction work or as a result of subsidence.

For more about our range of movement monitoring services, you can visit the movement monitoring page of our website HERE.

What if the structure I want to monitor is already damaged?

A damage monitoring survey is slightly different to a movement monitoring survey as there must be a visible form of existing damage there already; whether it is a hairline crack or a wall that is starting to lean due to suspected ground settlement or another cause of structural movement.

Wall movement monitoring can be carried out as standard on walls that have already started to move; however, crack movement monitoring is better surveyed via crack monitoring tell-tale indicators.

As part of a structure movement monitoring report, tell-tale crack monitoring is reported periodically by a monitoring surveyor so as to measure whether there is a change over time, or if the existing damage has stabilised.

For more on the different forms of movement, vibration and damage monitoring surveys available, the ICES have produced an in-depth guide at https://www.cices.org/content/uploads/2013/05/Client-Guide-to-Instrumentation-and-Monitoring.pdf. You can also contact SESE to discuss your specific project requirements.

How much would a building movement monitoring survey cost

The cost of a structural movement monitoring report depends on the location of a project as well as how many walls and points need to be monitored.

Movement monitoring projects in London cost from as little as £325 +VAT with same and next day monitoring surveyor attendance available for all our measured survey services including crack tell-tale monitoring and vibration surveys.

Booking a monitoring surveyor online in under a minute

Clients in need of either building movement monitoring reports or damage monitoring survey reports in London, can book a monitoring surveyor through our FREE online Quoting App and automatically receive a personalised on-the-spot price straight to their email in as little as 60 seconds by clicking HERE.

Once you have given a project location and preferred start date, select the days you want us, how frequently you want us, how many walls and points you need monitored, then select “reflectorless” if you do not think you need us to physically touch any walls. You can also click on the chat box below at any time in the process if you need more guidance from a member of our team.

As a supplier of engineering surveyor services throughout London and the UK Southeast, our ISO quality assured building movement monitoring services can also be booked in conjunction with our other services including below ground surveys, construction setting out, topographical land surveys, and fixed wing sUAV arial drone surveys for a more comprehensive site engineering survey package.

If you have any questions or require any further information, please don’t hesitate to call us now on 020 72 78 07 78 to find out how we can help with your structural monitoring surveys in and around London.

Ground penetrating radar (GPR) although a relatively new surveying technique for the construction and measured surveys industry, has been in use for almost a century as a scanning technique in both the medical and military arenas.

As a non-destructive engineering survey technique, below ground GPR surveys are an alternative underground utility mapping service, for environments where trial pits, boreholes and other forms of visual inspection are not the most feasible measured survey options for producing a utilities map.

A project GPR survey cost is usually made up of just a few factors, such as the size of the plot to be surveyed, the surface conditions, and the depth of scan required as these three factors determine which instrument would be best suited to the task.

As a PAS128 Type B survey, all our GPR survey services are managed by a professionally qualified GPR utility surveyor, and with our GPR Survey UK office based in London, we are within easy access of projects all over the Southeast.

An underground utilities survey is just one option for the use of ground penetrating radar, as it is also becoming commonplace for contractors wanting to locate reinforcement in concrete slabs, and developers in need of underground void surveys for a better idea of the homogeny of their land.

GPR Scanning works by sending a pulse of energy into a material via an antenna, a reflection of that pulse is then received (through a receiver) and processed (by a computer) where both the strength of the returned signal and the time it takes for that signal to return are recorded.

As these reflections are caused by changes in material properties, this works brilliantly in well graded ground but is a problem in backfilled soils; it is one of the roles of a GPR utility surveyor to be able to spot the difference.

A ground penetrating radar survey cost can also vary depending on the type of deliverables you need. A brief on site visual inspection of B-Scans would be cheaper than a postprocessed report which typically includes topographical surveys and merged C-Scan tomography plans to help clients visualise exactly what is happening at predetermined depth intervals.

Safety is often the main reason for a below ground services survey and detecting whether there are pipes, conduits, structural voids, and reinforcement within a dig area beforehand will help avoid having to make the decision between penetration, or resolution as accidental penetration can be extremely costly and even cost lives.

As a supplier of engineering surveyor services all over London and the UK Southeast, our ISO quality assured below ground survey services can also be booked in conjunction with our other services including terrestrial topographic land surveys, construction work setting out, movement monitoring surveys, and fixed wing sUAV arial drone surveys for a comprehensive engineering survey package.

For an instant quote on how much a ground penetrating radar survey should cost UK wide, click HERE to use our FREE GPR Service Quote App; and receive our price via email in as little as 60 Seconds.

Alternatively, if you have any questions or require any further information, please don’t hesitate to contact us on 02072780778 now to find out how much your ground penetrating radar survey should cost.

All too commonplace within the construction industry, are stories where a small error in positioning and setting out can cause immense knock-on effects to the project and bottom-line. The block of flats in Colchester that were built the wrong way around just last October, a £12m development project in Stane Park where a mis-position of a few centimetres caused months of delay. A new build house in Mendlesham Green, Suffolk with a demolition enforcement action notice for being 4.5m out of position and a Cineworld in Cambridgeshire that was built in the wrong place – twice, initially mis-positioned by 75cm and then 36cm.

Construction site setting out has always been one of the primary tasks of site engineers. Often studying degrees like Civil Engineering and Geodetic Surveying, there are many routes into becoming a site engineering surveyor and positioning millions and sometimes billions of pounds worth of assets.

As a site engineer, setting out tasks vary from day to day, from setting out construction infrastructure such as the pile positions of a new build to marking out the overlay of measured surveys from existing utilities; with plenty of site levels, drainage runs and gridlines in between.

Hiring competent site engineers for site setting out projects is particularly important in dense cities such as London, where land values are high, and accuracy is vital given the limited space.

Professional setting out exists to introduce greater predictability to the cost of a construction project by reassuring contractors, developers and self-builders of their dimension and location accuracy

If you have any questions or require further information about our setting out engineer services, please do not hesitate to contact us. At SESE Ltd we have a wealth of experience and knowledge in providing setting out services across London and the Southeast. To find out if your project would benefit from any of our site engineering services or for a quick setting out surveyor quote call our office on 020 72 78 07 78 during office hours, or click HERE  at any time, 24 hours a day 7 days a week.

There have been several incidences over the years where structural movement monitoring would have come in very useful. In November 2020, two West London townhouses collapsed during construction work that was going on inside them; considering that less than a year before this, a similar townhouse on the same terrace sold for more than £15,000,000 the reparation costs for this collapse would have been substantial. Costs that could have been avoided through a relatively simple and cheap building movement monitoring system.

Clearly, this error could have ended up costing far more than two historic 18^th Century Chelsea townhouses and a hefty insurance claim, but for the fact that the buildings collapsed late at night, while the street was relatively empty and there was no one inside the two buildings.

Unfortunately, this is not the first time this sort of incident has happened. In April 2017 a £1M house collapsed during basement construction work in Derwent Avenue, Kingston; and in November 2015 an end of terrace property in SW London collapsed during basement extension building work that was taking place inside.

Monitoring Building Movement

The purpose here is to answer the question we frequently get asked at South East Site Engineers; what is the point of monitoring our building work?

Like everything else on the planet, buildings are constantly moving; this movement may be exaggerated during excessive vibration from road traffic, trainlines, or tunnels, and of course material movement during construction work; especially basement construction work.

When underpinning an existing building (the process of constructing a basement or lowering the existing floor level beneath an existing building) this movement is exaggerated because our contact with that building is now direct.

Movement monitoring reports provide clients and contractors with evidence of the extent of movement in their building at the designated monitoring points, before, during, and after the construction and/or demolition work.

“Early warning systems” like these are designed to notify interested parties as and when a buildings’ movement is starting to approach the given trigger levels and in exactly which parts of the building this heightened risk is occurring. All in order to avoid what could be a catastrophic disaster.

It is never too late to act…

Damage Monitoring Surveys

Even in the event where damage is already evident, it is often wise to call an engineering surveyor to monitor existing cracks, either using reflectorless monitoring points (in hard-to-reach places) or tell-tale gauges. What you really want to be sure of is that your structural movement is not continuing significantly over time. A damage monitoring survey proposal is often best reviewed by your structural engineer before deciding the extent and location of the required building movement monitoring system.

As a form of measured survey and very much part of the site engineering process, the cost of structural movement monitoring reports varies. It often depends on how large a monitoring survey you require, your project location, and how frequently movement monitoring visits are required. To get an idea of monitoring survey costs for your project click HERE to use our FREE Movement Monitoring Quote App.

This article is a brief overview of movement monitoring. If you have any questions or require any further information please don’t hesitate to contact us. Alternatively, you can find more about our structure monitoring services on our movement monitoring service page.

Here at SESE Ltd we have a wealth of experience and knowledge in providing both construction and demolition monitoring solutions across London and the Southeast.

To find out if your structure requires movement monitoring or for a structural monitoring survey quote please call our office on 02072780778 or book online HERE  24 hours a day 7 days a week.

Structural Movement Monitoring, put simply, is the process of measuring and assessing the effects of a construction activity, demolition activity or civil engineering companies’ groundworks activity on an adjacent structure, usually within a metre or so of the construction site. This damage monitoring survey technique is carried out over fixed predetermined return periods (during the Pre-construction, Construction and Post-construction phase) with the readings given to the client together with an easy-to-read graphical illustration of any movement.

WHY IS STRUCTURAL MOVEMENT MONITORING REQUIRED?

WHY CHOOSE US FOR YOUR STRUCTURAL MONITORING SURVEY?

• At SESE our structural movement monitoring and measured building surveyors have an excellent reputation for commercial and private property monitoring services and specialise in building surveys for homes and businesses throughout the UK.
• From our office in Islington, London, our site engineering and setting out team deliver valuable advice and guidance in order to assist prospective and current clients, such as borough councils, construction companies, demolition companies, property owners, architects, structural engineers, and private developers in making viable decisions about their projects.
• We have over 20+ years’ experience at your disposal, so not only are our engineers highly competent at dealing with different forms of residential and commercial structural movement monitoring, we also integrate and deal with a range of setting out engineer services like gridline setting out and building profiles, as well as GPR services and topographical surveys for homes and businesses alike.