Prior to construction and infrastructure projects, it may be necessary to characterise landscape features to assess their suitability for design purposes. Resistivity imaging is often employed due to its ability to penetrate up to depths of 30m+.
Resistivity Imaging is often used to:
-
Measure bedrock & water table depths
-
Detect sinkholes & hidden voids
-
Map buried alluvial channels
-
Profile landslip geometry
-
Characterise fracture zones & discontinuities
-
Define landfill sites and leachate contamination
-
Locate abandoned mineshafts and mine workings
The Process:
Resistivity imaging techniques employ a line of electrodes temporarily inserted in the topsoil through which electrical current is made to flow. The voltage is converted into a resistivity value. This represents average ground resistivity between the electrodes. Different materials have different resistances, which are linked to moisture content, or porosity. Hard, dense features such as rock will give a relatively high resistance while features such as ditches, which retain moisture, give a lower response. This means that bedrock, fissures and other geological features can be mapped.
Above : Resistivity imaging survey sampling sequence.
Depth probes provide models of vertical variations in ground resistivity using an expanding electrode array offset from a central reference point. Depth penetration increases with wider electrode separation. This provides a one dimensional layered resistivity model. Composite sections are produced by interpolating between depth probes at regular intervals along a survey line. Electrical Resistivity omography (ERT) (also known as Resistivity Imaging), is an advanced development of the method. Enhanced data quality and resolution provide continuous two-dimensional resistivity models. Fifty or more electrodes are set out in an evenly spaced array, and connected to a computer-controlled resistivity meter.
Unit electrode spacing is determined by parameters that include profile length, desired resolution and targeted depth penetration. A switching unit takes a series of constant separation readings along the length of the electrode array. The separation between sampled electrodes is then widened to increase the effective depth penetration and the procedure is repeated, as shown above. Readings are taken down to 20 levels of increasing depth range. This means that we can assess larger deeper and shallower smaller features.
Above : Assessing slope stability by resistivity imaging.
The Deliverable:
Advanced data processing using specialist inversion software removes distortions caused by the effects of electrode geometry. It produces a high-resolution image of the variations in ground resistivity with depth. The model is contoured using a colour scale to produce a two-dimensional cross-sectional model of ground resistivity. Our geophysicists use the final resistivity imaging section to provide clients with a detailed interpretation of the ground conditions on site.
Above : Topographically corrected Resistivity Imaging over long barrow.
-
How accurate is SUMO's underground utility survey and what types of utilities can it locate?Using cutting-edge technologies like electro-magnetics, signal induced threading, and Ground-Penetrating Radar (GPR), our underground utility surveys accurately detect a wide array of buried utilities including metal and plastic pipes, drainage systems, electricity cables, telecoms, and fiber optic cables. The methodology ensures high accuracy without the need for invasive trial holes.
-
What is the turnaround time for obtaining results with SUMO's Underground Utility Detection service?SUMO’s service is built for rapid response. Contractors can receive immediate results onsite. Our equipment provides real-time information, and once we leave the site, the detected utilities are visibly marked on the ground surface for quick reference.
-
Does SUMO provide detailed mapping of the detected utilities for permanent records or construction purposes?Absolutely, SUMO not only marks the detected utilities on-site but also offers high-quality, color-coded survey drawings. These drawings can include topographic features and a comprehensive record of the utility detection survey, ensuring it meets the client’s needs for future reference or pre-construction design works.
-
Topographical and Geophysical surveyIn addition to mapping out utilities, our experience team can accurately survey the land, creating topographical drawings for use. With our state-of-the-art aerial technology, nothing is missed.
-
What additional information can be included in the underground utility mapping service provided by SUMO?In addition to topographic features, SUMO’s mapping service can include fixed surface utility features such as inspection chambers, valve boxes, and telegraph poles. It can also incorporate key topographic details like building lines, fence lines, kerb lines, street furniture, street names, building names, and house numbers, facilitating easy site location.
-
Does the utility mapping service by SUMO include standard referencing and compatibility with existing survey data?Yes, SUMO ensures the utility mapping references the ordnance survey grid and level datum as standard. Additionally, the drawings can be supplied to a specified grid and level datum and can overlay an existing topographical survey, making it a versatile and adaptable service for various project needs.
-
What sets SUMO Services apart from other survey providers?SUMO stands out due to our impeccable level of service with nationwide coverage, state-of-the-art equipment, and our commitment to delivering top-quality, detailed colour-coded survey drawings in both hard and electronic formats.
-
How do I request a survey quotation from SUMO Services?Requesting a quotation is easy. Just click on the "Request a Survey Quotation" button on this page, and our team will get in touch with you promptly.
-
Can I book a SUMO Survey online?Yes, you can! Simply click on the "Book a SUMO Survey" button on this page, and you can schedule your survey with us at your convenience.
-
What type of survey is suitable for my project or site?Our experienced team will work with you to determine the most appropriate survey for your specific needs. Contact us, and we'll assist you in making the right choice.
-
Can I obtain both digital and hard copies of survey drawings?Absolutely. We offer the convenience of electronic copies for digital use and hard copies for your records. Just let us know your preference.
-
Do you provide custom survey solutions for unique projects?Yes, we understand that every project is unique. Our team is highly adaptable and can tailor our surveying services to meet your specific requirements.
-
How do I get in touch with SUMO Services for further questions?For any additional questions or inquiries, feel free to contact us through the contact form, and our dedicated team will assist you promptly.
Survey Methodologies
Detailed Magnetic Survey
Soil Self-Potential
Electrical Resistivity Tomography (ERT)
Soil Thermal-Resistivity Testing
Electromagnetic Ground Conductivity
Electromagnetic Location (EML)
Ground Penetrating Radar (GPR)
