Search Results

SUMO Successfully Complete An As-Laid Services Contract On One Of Their Biggest And Most Complex Sites To Date. SUMO recently completed a highly complex utility survey at an airfield in advance of a major restructuring project to redevelop the area as a world class training facility. The airfield was closed prior to the works, which included the site-wide upgrade of the existing utilities infrastructure across a 1,200-acre area within a tight 18-month programme. Following the detailed utility survey, the final deliverables were presented on 117 sheets at a scale suitable for legibility of detail. As-laid contract With respect to the upgrade of the existing utilities network, SUMO were commissioned to carry-out an as-laid survey of the newly installed services over an 18-month contract. The services comprised of HV and LV cables, Fire mains, Potable water mains and Gas mains. The total length of these services was approximately 27km. In addition to the pipeline routes (Water, Gas & Fire), all associated fittings comprising of washouts, air and scour valves, stop vales, metres, hydrants, and pressure reducing valves, plus electric cables, transformers, feeder pillars and sub-stations were all detailed for inclusion in the final deliverables. To carry this out, SUMO’s surveyors visited the site on a weekly basis over the 18 months, to record the position of the installed services on a rolling program. With up to 12 working crews installing services across the site at any one time, this created a significant logistical challenge to not only locate the working crews and record their latest works, but also the access to and parking of vehicles on site was severely restricted for security reasons, making the task even more difficult. To deal with these complications, a GPS Rover unit was used to accurately record the as-laid services. This equipment uses the Trimble VRS solution for corrections referenced to the Ordnance Survey Grid, meaning that the GPS could be used anywhere on the site, with the added advantage of being easily portable and carried by the surveyors, walking the many kilometres required on each visit. A huge number of photographs were also taken as a visible record of the site, to assist in piecing together the jigsaw puzzle of pipes and cables. Due to the number of site photographs taken, this also necessitated creating a digital database. Using the CAD model, camera icons were then inserted in the actual positions that the photographs were taken and the camera icons included a photo reference number, date of capture and a hyperlink which accessed the photograph when clicked. Deliverables: The end user client stipulated that the minimum number of drawing sheets absolutely necessary for ease of reference and practical use on site were required. In addition, individual drawing sets were needed of each of the 4 utilities: fire mains, water mains, potable water mains and electric cable routes. Accordingly, in order to meet this requirement, a compromise had to be reached with relation to the scale of detail. It was therefore decided that 7 sheets of A0 drawing sheets at a scale of 1:500 would be created for each of the utility sets to cover the site. The compromise reached was to create a ‘hybrid’ of accurate digital data (model) and schematics, where the representation of fittings such as valves etc., would not be to scale, but shown at a size and relative positon only, for ease of visualisation. Accurate details, when required, could then be interrogated from the digital model. Above: Example of Potable water schematic with valve identifiers (similar for Fire and Gas) and symbols (right). Symbols were then created as blocks to represent the fittings as a simple visual reference and for ease of insertion into the drawings. Similar blocks were created for Fire main and Gas main drawings. Electric Cable routes (HV & LV) Although there was an attempt to survey the individual electric cables within the defined routes (trenches), this could not always be achieved due to the large number of cables in certain areas, crossing over, partially buried or too bunched together. However, in consultation with the senior electrical engineer, we were able to identify the routes of individual cables from the transformers / feeder pillars to the supply side where they entered the buildings and these were shown as schematic layouts. Above: Example distribution of cables from sub-station and enlargement of sub-station showing individual cable routes, ring main unit (RMU), transformers (TX1), feeder pillars (FP) and earth rods. The same approach was then applied to the gas mains. Above: (Left) Example extract schematic showing gas pipes, pipe sizes, valves. (Right) Gas pipes installation. Through constant communication and collaboration with the client, plus SUMO’s flexibility in organising multiple survey teams working throughout the base, as and when needed, the project was undertaken within the necessary deadlines. Furthermore, the ability to send data back to our Central CAD office electronically, enabled SUMO to provide preliminary results within hours of each site visit, meaning that the client could have a timely overview of the contractor’s ongoing progress over the entire site and identify any problem areas at an early stage. The enormity of the site meant that the sheer volume of deliverables would normally be unworkable in this type of dynamic environment, however regular consultation with the client allowed us to devise and provide a practical solution. As a result, we were able to provide unique working drawings at a suitable scale which tied in with a bespoke digital model with supporting photographic evidence, thereby enabling the client and their contractors to complete the project on time and with minimal disruption. All in all, it was a complex and at times stressful project, but one in which everyone was delighted and proud of the end result. So, no matter how big (or small) your project, why not give SUMO the opportunity to find the solution that best meets your needs? Contact us now on 0845 456 1104…

Above: A close-up picture of the ‘Blue Stones’ of Stonehenge. Headed up by Adam Stanford, SUMO’s Director of Aerial Survey, Aerial-Cam Limited provides a specialist geospatial imaging service employing the latest techniques, equipment and software to produce high quality evidence photography, photogrammetry and multispectral imaging, recording features and evidence in archaeological excavations, topography and earthworks of landscapes and ancient monuments. Also surveying historic buildings to produce 3D models, rectified orthomosaic elevations, plans and roof details. Above: Processed data captured from a UAV. Above: 3D image model. Adam is a Member of the Chartered Institute for Archaeologists, the Council for British Archaeology and a Fellow of the Society of Antiquaries. With expertise in photography, archaeological field work and surveying experience spanning three decades, Adam has been involved with the Stones of Stonehenge and related projects for 15 years. Adam’s work can now also be seen in a new documentary ‘Stonehenge: The Lost Circle Revealed’ on BBC2: In the programme, Professor Alice Roberts follows a decade-long historical quest to reveal a hidden secret of the famous bluestones of Stonehenge. Using cutting-edge research, a dedicated team of archaeologists led by Professor Mike Parker Pearson of the Institute of Archaeology, University College London, have painstakingly compiled evidence to fill in a 400-year gap in our knowledge of the bluestones, and to show that the original stones of Britain’s most iconic monument had a previous life. Together they join the final pieces of the puzzle, not just revealing where the stones came from, how they were moved from Wales to England or even who dragged them all the way, but also solving one of the toughest challenges that archaeologists face. For anyone interested in Stonehenge or archaeology generally, the programme makes a fascinating watch.

Crops, clay & clutter and how they affect your archaeological survey. Geological and buried manmade features or objects can cause local variations in the earth’s magnetic field, which can be measured with a magnetometer. Accordingly, a detailed magnetic survey can be used to effectively define areas of past human activity and it is a quick, cost effective technique. As such, it has become the industry standard for archaeological surveys. However to obtain successful results from your archaeological (magnetometer) survey, several factors must first be taken into consideration. The most important is the nature of the ground conditions, especially when there are crops growing on the fields. We have therefore set out below, a list of the perfect conditions for geophysics to help you get the most out of your archaeological survey. In an ideal world, all survey sites would have the following ground conditions: - 1. Short pasture, or early season crops 2. ‘Stubble’ - short crops after the harvest 3. Lightly ploughed fields Lightly ploughed fields which have been prepared for crops can be easily surveyed. But, if the plough is deep or the field contains clay soils, then it can become tricky or even impossible to survey. So, what ground conditions are unsuitable for archaeological surveys? Factors affecting the magnetic survey may include soil type, local geology, previous human activity, disturbance from modern services etc. The physical state of the ground itself can also significantly affect the result of the survey, especially rough or uneven surfaces. SUMO understands that the ‘perfect’ survey conditions will rarely be achievable due to the nature of individual sites, but we have listed examples of unsuitable ground conditions for archaeological surveys below: 1. Old potatoes fields/ Oilseed rape fields 2. Overgrown sites 3. Potato fields 4. Untidy, dumped material Are there other factors which affect the carrying out of magnetometer surveys? Livestock - for safety purposes, livestock should be removed from survey areas. Agricultural work i.e. certain crop sprays can make fields unsafe for personnel to survey. Example magnetic survey equipment which can either be towed by a quad bike (where conditions allow) enabling large amounts of data to be collected quickly, or man powered, which is somewhat slower! Smaller two sensor arrays which can be carried by an individual are also used in less open sites. SUMO will always discuss the survey area with its clients to understand its current use and to tailor its approach wherever possible. Most archaeological surveys are carried out using magnetometry but Ground Penetrating Radar (GPR) is being employed more often. While the same ground conditions apply for GPR as they do for magnetic survey, there are a couple of other issues which need to be considered. Clay or clayey soils can severely restrict the use of GPR in that the energy waves cannot penetrate through dense soil structure. A high water-table will also limit the depth of penetration. Above: Ground Penetrating Radar (GPR) equipment. Seasonal factors can also affect geophysics surveys both positively and negatively… The spring months: Early spring is an ideal time for a survey, when the weather is improving and the land is drier, but before the crops have grown significantly. New crops can be delicate and severely impacted by either cart systems or trampling under foot which can result in the landowner being unwilling to authorise a survey until the crop has matured or even been harvested. The summer months: Tall crops can interfere with magnetometer sensors. This can make it impossible for the operator to walk safely. Maize fields are the worst! This is because despite the harvest, the remaining stalks can be extremely brittle. This causes problems for the surveyors walking the site. It is impossible to collect underground GPR mapping data in potato fields. Other root crops are less of a concern unless the ground is heavily rutted. The summer is also an ideal time for aerial surveys, when archaeological features can often be seen as a result of the differing moisture contents between archaeological remains and the surrounding land. The autumn months: Immediately after harvest is a perfect time for a survey, when the land is dry and the weather is good. The busiest times of year for carrying out archaeological surveys are therefore spring and autumn, when clients can take advantage of the preferred ground conditions. As such, SUMO would always advise its clients to book surveys as early as possible at these times to ensure their preferred dates. Why should you use SUMO? With over 40 years’ experience at the forefront of geophysics, we pride our survey offering on the following: We employ many of the industry’s leading survey professionals. All our surveyors are multi-skilled to aid flexibility and tailoring of our services. Our unique size and nationwide coverage allows us to tailor our service to a client’s individual needs and budget. So, beat the rush, get your order in early and don’t let your competitors get that all important survey slot!

Sinkholes have been appearing throughout Britain at an alarming rate in recent years. Following heavy rainfall, the ground becomes saturated and as the water levels recede, they can wash out material, leaving substantial life-threatening voids to appear without warning. Some rock types are more susceptible to the formation of sink holes, with carbonate rocks including chalk and limestone being particularly sensitive, as they can be easily dissolved by groundwater. Furthermore, if the rock is overlain by clay material, this forms a configuration that can produce a large void that suddenly collapses when the clay layer above fails. Less dramatic sinkholes also occur where the overlying material is more porous and slowly ingresses into the underlying void resulting in a gradually deepening depression over time. With chalk prevalent in England’s South Eastern counties, along with areas of limestone in Wales and Northern England, the impact of sinkholes can be significant, both in terms of risk to life and financial cost. So, if a sinkhole suddenly appears, or you have an unexplained depression on your site, you urgently need to know the extent of the problem, its likely cause and the risk of more incidents. Thankfully, SUMO has the answer to this problem: SUMO Geophysics can complete a full geophysical survey of the area, using ground conductivity and/or ground penetrating radar. Electromagnetic ground conductivity surveys measure ground conductivity by the process of electromagnetic induction. A current is induced into the ground to generate a response from the sub-surface. This is done utilising a transmitter and receiver coil spaced at a fixed configuration, with different operating frequencies providing a range of depth penetration and resolution for different applications and can be used to identify anomalous features underground, such as saturated ground and landfill. The EM31, a particular ground conductivity system, operates at an intermediate frequency and is ideal for locating discrete features such as sinkholes. Above: Ground Conductivity Survey to locate sinkholes using a Geonics EM31. The data is digitally recorded on site for later post-survey processing and interpretation. The data is processed with specialist software to produce contour plans. The contoured data is then analysed in detail to identify anomalous features relative to the general background and once identified, the anomalies are correlated with local ground conditions. Survey results are then presented as plans tied in to site or OS co-ordinates, in AutoCAD and PDF format. The example below shows the results of the ground conductivity survey, following the appearance of a hole in the middle of a school playing field. The survey identified a notable high conductivity anomaly, which has been interpreted as occurring where saturated gravels are present over the underlying chalk stratum. It is likely that groundwater within the gravels has seeped down to the chalk and is generating the formation of solution features. Furthermore, as this groundwater flow in the gravels is likely to continue, then further solution features are likely to occur and with them, further sinkholes. Ground Penetrating Radar (GPR) surveys work by pulsing electromagnetic waves into the ground and measuring the strength and time delay of the returning signal, which also allows it to approximate the depth of the underground anomaly identified.It has capacity to work through a wide variety of surface materials, from soft landscaping, through to hard surfaces such as tarmac and concrete both inside and outside buildings. Above: GPR survey using GSSI Radar system and 400MHz antenna. The data is collected along set grid spacing and displayed as a section view or profile of the ground. Large or obvious anomalies may be interpreted on site, but the data is typically analysed and processed in the office after the survey is completed. Each radar profile is abstracted and significant anomalies are classified. This is the primary source for producing the 2D interpretation plot. Above: Example radar data showing area and depth of anomaly likely to be voiding below the ground. In addition to a manual abstraction, a computer analysis is carried out. The radar data is interrogated for areas of high activity and the results presented in a plan format known as timeslice plots using GPR Slice software. In this way it is easy to determine if the high activity areas form recognisable patterns. Above: GPR timeslice plot showing the location of possible voids. Conclusion: The use of a combined geophysics survey can not only identify the depth and location of an underground anomaly, but with expert interpretation, may also identify the likely cause of a sinkhole or unexplained ground depression, together with the potential risk of more such incidents occurring. As such, given both the risk to life and the financial cost that such anomalies present, the low cost option of a geophysics survey is an excellent solution to mitigating such risks.