--- title: What Survey Information Do Contractors Need Before Starting Groundworks? description: Know the essential survey information UK contractors need before starting groundworks, from topographical levels and utility mapping to drainage details and setting-out data. image: https://intersectsurveys.co.uk/hubfs/intersect-land-surveying-home-1.jpg --- [![Intersect-surveys-logo-dark](https://intersectsurveys.co.uk/hubfs/Intersects_2022/images/Intersect-logo-dark.png)](https://intersectsurveys.co.uk) - [Surveys](https://intersectsurveys.co.uk/utility-surveying-services) - [Utility Surveys](https://intersectsurveys.co.uk/utility-surveys) - [GPR Surveys](https://intersectsurveys.co.uk/gpr-surveys) - [PAS 128 Surveys](https://intersectsurveys.co.uk/pas-128-surveys) - [Topographical Surveys](https://intersectsurveys.co.uk/topographical-surveys) - [Site Control & Setting Out](https://intersectsurveys.co.uk/site-control-setting-out) - [Construction Verification As-Built](https://intersectsurveys.co.uk/construction-verification-as-built) - [Measured Building Surveys](https://intersectsurveys.co.uk/measured-building-survey) - [Environmental Monitoring Solutions](https://intersectsurveys.co.uk/environmental-monitoring-solutions) - [Structural Monitoring Solutions](https://intersectsurveys.co.uk/structural-monitoring-solutions) - [Right To Light](https://intersectsurveys.co.uk/right-to-light) - [CCTV Drainage Survey](https://intersectsurveys.co.uk/cctv-drainage) - [Desktop Utility Record Search](https://intersectsurveys.co.uk/desktop-utility-record-search) - [Sectors](https://intersectsurveys.co.uk/sectors) - [ABOUT](https://intersectsurveys.co.uk/about) - [BLOGS](https://intersectsurveys.co.uk/blog) - [Our Work](https://intersectsurveys.co.uk/blog/tag/case-study) - [Ebooks](https://intersectsurveys.co.uk/survey-ebook-library) - [Contact](https://intersectsurveys.co.uk/contact-us) - [0208 399 3851](tel:02083993851) # What Survey Information Do Contractors Need... Groundworks are the foundation of any construction project, quite literally, and getting them wrong... - Get Straight Through to an Expert ## What Survey Information Do Contractors Need Before Starting Groundworks? [Admin,](https://intersectsurveys.co.uk/blog/author/admin) 26 Oct, 2026 Groundworks are the foundation of any construction project, quite literally, and getting them wrong can be disastrously expensive to put right. Striking an unknown utility, building on inaccurate levels, or misjudging drainage can halt a site overnight and expose contractors to serious liability. That's why thorough survey information is essential before a single machine breaks ground. Knowing exactly what data to gather – and in what form – allows groundworks to proceed safely, accurately, and without costly surprises. ## **Why Survey Data Matters Before Breaking Ground** Groundworks contractors work to tight tolerances, and the information they receive at the outset determines everything from excavation depths to foundation positions. Poor-quality or missing survey data is one of the most common causes of delays, variations, and disputes on UK construction sites. Accurate surveys protect both the contractor and the client. They reduce the risk of hitting buried services, ensure compliance with regulations such as [**CDM 2015**](https://www.hse.gov.uk/construction/cdm/2015/overview.htm), and provide a reliable baseline against which all subsequent work can be measured. ## **Topographical Survey Data and Site Levels** A [**topographical survey provides the fundamental picture**](https://intersectsurveys.co.uk/topographical-surveys) of the site as it currently exists, and contractors rely on this heavily during the groundworks phase. Here's what it should include: - Existing ground levels and contours, referenced to Ordnance Survey datum - Site boundaries, fences, and walls marking the legal extent of the works - Existing structures and hardstanding that may affect excavation or access - Trees and root protection areas, particularly where TPOs apply - Visible drainage features, such as manholes, gullies, and watercourses These levels form the basis of all cut-and-fill calculations, so accuracy here directly affects earthworks costs. If levels are wrong, contractors may excavate too much or too little, both of which have serious cost and programme implications. ## **Underground Utility Mapping and Detection** Striking a live utility is among the most dangerous and expensive mistakes a contractor can make, so knowing what's beneath the surface is non-negotiable. A combination of records research and physical detection should provide: - Statutory utility drawings, obtained via the LSBUD (Linesearch BeforeUdig) service - [**GPR survey results**](https://intersectsurveys.co.uk/gpr-surveys), identifying non-metallic pipes and unknown services - Electromagnetic location data, tracing live cables and metallic services - Trial holes or boreholes, physically confirming depths at critical crossing points - Abandoned service records, highlighting legacy infrastructure that records may miss Under the Health and Safety at Work Act, contractors have a duty to take reasonable steps to avoid utility strikes, and robust survey data is central to discharging that duty. Never rely on statutory drawings alone — they show location, not depth, and are often inaccurate. ## **Drainage and Levels Information** Drainage design depends entirely on accurate level data, and groundworks teams need this information before the first trench is dug. Key details include: - Invert levels of existing manholes and inspection chambers - Connection points to public sewers, including adoption requirements under the Design and Construction Guidance (part of the Sewerage Sector Guidance). - Foul and surface water separations, confirming the correct system for each outfall - Flood risk data, particularly on sites within Environment Agency flood zones - Existing watercourse positions, where consents may be required Poor drainage is one of the most common causes of post-completion defects in UK housing, and many issues can be traced back to inadequate survey information at groundworks stage. Getting levels right at the outset prevents the cost and disruption of re-grading an entire site after completion. ## **Setting-Out Data and Control Points** Once excavation begins, contractors need precise reference points to position foundations and structures correctly. Survey control should be established and shared well before work commences: - Primary control stations tied to OS grid and datum - Setting-out coordinates for all foundations, pile positions, and structural gridlines - Benchmarks for levels, used consistently across all trades - Site datum documentation, ensuring everyone works to the same reference - As-built verification plans, confirming completed work matches design intent Consistency of control is vital on larger sites where multiple contractors may be working simultaneously. A single agreed datum and control network prevents the classic error of one trade building 50 millimetres higher than the adjacent one. ## **Geotechnical and Ground Investigation Data** Understanding what lies beneath the topsoil is just as important as knowing what's on the surface. Ground investigation reports should be made available to the groundworks contractor, covering: - Soil borehole logs, describing strata, strength, and consistency - Trial pit records, revealing groundwater levels and made ground extent - Contamination reports, identifying any remediation requirements - Load-bearing assessments, confirming foundation design assumptions - Slope stability data, on sites with embankments or previous land use Unexpected ground conditions are one of the biggest sources of groundworks variations, and a thorough ground investigation dramatically reduces this risk. ## **The Right Survey Data Is Your Safest Investment** Comprehensive survey information is not an administrative box-ticking exercise — it is the foundation upon which safe, accurate, and profitable groundworks are built. Contractors who insist on complete data before mobilisation consistently deliver better outcomes with fewer disputes and delays. Cutting corners on surveys at the outset almost always costs far more than the surveys themselves.[Insist on quality verified data from Intersect Surveys](https://intersectsurveys.co.uk/) before breaking ground, and your groundworks will proceed smoothly from day one. [Previous Article: How Can 3D Laser Scanning Improve Accuracy in Complex Construction Projects?](https://intersectsurveys.co.uk/blog/how-can-3d-laser-scanning-improve-accuracy-in-complex-construction-projects) #### A reliable and efficient company ”We've been working with Intersect for several years and have always found them to be reliable, efficient and good value for money. I can honestly recommend them." ![testimonial-image](https://intersectsurveys.co.uk/hubfs/Intersects_2022/images/intersect-section-divider.png) Peter F , Commercial Director #### Excellent customer care ”The whole process was very smooth from start to finish, with excellent communication and customer care. 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A small shift in a retaining wall, a spike in dust... [Read More](https://intersectsurveys.co.uk/blog/alerts-reduce-structural-environmental-risk) [![structural monitoring vs environmental](https://intersectsurveys.co.uk/hubfs/1000017584.jpg)](https://intersectsurveys.co.uk/blog/structural-environmental-monitoring-when-you-need-both) #### [Structural vs. Environmental Monitoring: What's the Difference and When Do You Need Both?](https://intersectsurveys.co.uk/blog/structural-environmental-monitoring-when-you-need-both) [Alex Shiels](https://intersectsurveys.co.uk/blog/author/alex-shiels) 15 Jul, 2025 Why Environmental Monitoring Can’t Be Ignored As urban development grows more complex, project teams face rising... [Read More](https://intersectsurveys.co.uk/blog/structural-environmental-monitoring-when-you-need-both) [![structural monitoring](https://intersectsurveys.co.uk/hubfs/oaklands%20college-1.jpg)](https://intersectsurveys.co.uk/blog/environmental-monitoring-is-no-longer-optional-construction-sites) #### [Why Environmental Monitoring Is No Longer Optional for Construction Sites](https://intersectsurveys.co.uk/blog/environmental-monitoring-is-no-longer-optional-construction-sites) [Alex Shiels](https://intersectsurveys.co.uk/blog/author/alex-shiels) 14 Jul, 2025 Why Environmental Monitoring Can’t Be Ignored Construction sites today operate in a climate of increased... [Read More](https://intersectsurveys.co.uk/blog/environmental-monitoring-is-no-longer-optional-construction-sites) ## Get in touch Choose Intersect Surveys as your preferred provider. Simply fill out the form and an expert will be in touch to handle your enquiry. 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