Volume Calculations & Analysis
- 3D Topographical / Land Survey
- Volume Calculations & Analysis
Sector: Construction & Engineering
About This Project
SurveyWorx were commissioned to manage & deliver the Survey Specification, working in collaboration with the Construction, Engineering & Design Teams who would lead the Project.
We were tasked with the planning & delivery of Topographical Survey (3D), DTM & Volume Analysis of the Site. Volume Analysis was required to determine the amount of space remaining in one area of the Site to deposit waste prior to the facility closing all Waste Management operations.
The Landfill Site covered approx. 50Ha, comprising an internal perimeter access road measuring approximately 3.6km, in addition to 1.5km of public highway skirting the northern boundary.
Survey Methodology & Project Delivery
We deployed a combination of integrated Robotic Total Stations & GNSS Technology & “Robust Survey Methods” to capture & verify accurate Survey Data & deliver the Survey Specification.
Establish Control Network Framework
The Survey Control Network was established using a combination of GNSS, Total Station (1”) & Precise Levelling with Primary Survey Stations established every 120m along the public highway & internal perimeter access road skirting the Landfill.
Survey Control Network Post-Processing
Field Observations/Readings were Post-Processed through SCC Survey Software to calculate Least Squares Adjustment & Analysis (Residuals, Standard Errors, Error Ellipses) to produce final Control Network Coordinates.
Survey Data was captured using a combination of Robotic Total Station (hard standing features) & RTK GNSS (soft standing features). Spot Levels were observed at 10m Grid Interval Across the Site to provide sufficient Survey Data for Contour Mapping & Volume Analysis across the Site. Survey Data was Post-Processed through SCC Survey Software to produce Contour Mapping with final editing completed in AutoCAD.
Volume Calculation & Analysis
The 3D Topographical Survey would be used as a base/reference for Volume Analysis with a second Surface Model Created to represent the “Proposed/Final Design Surface” which was determined by the maximum allowed height of the completed Landfill Surface.
3D Points (10m Grid Interval) were created manually to define the “Proposed/Final Design Surface”.
Prismoidal Projection Method or Surface to Surface Method; Volume Analysis involved the creation of an Isopachyte/Thickness Model from the two Surfaces under consideration. This was achieved by calculating differences in height from all Surveyed Points, & along all Surveyed Strings, in both 3D Models, & triangulating the result. Once the Isopachyte Model had been formed, Prismoidal Volumes were calculated by adding the volume of each triangular prism generated by projecting the Isopachyte triangle to a Datum of zero.
The Volume Calculation Report generated from the volume computation showed us the Plan & Surface Areas under consideration as well as the total Cut & Fill Volumes.
Quality Assurance/Data Validation
Surface to Surface Method versus Grid Volume Method
Grid Volume Method; Volume Analysis was also completed using the Grid Volume Method. This option is similar to the Prismoidal Method, except that the volumes are derived from a regular grid of rectangular prisms, with each prism generated by calculating height differences for the four grid points that make up its vertical edges. The Volume was computed as the sum of the volumes of the individual prisms.
Analysing both results allowed us to cross reference & confirm final calculations against the Prismoidal Method.
Coordinate Reference System
Delivery & Output
The difference between the two Surfaces under consideration allowed us to determine the amount of available space remaining for waste disposal with the final Model exported to 3D AutoCAD along with a detailed Volume Calculation Report.
The completed Survey & Digital Terrain Model (DTM) was delivered as a digital version in 3D AutoCAD & PDF format.
GNSS = Global Navigation Satellite Systems.
RTK = Real Time Kinematic.
GPS = Global Positioning System.
OSGB36 = Ordnance Survey National Grid Reference System.
ETRS89 = European Terrestrial Reference System.
WGS84 = World Geodetic System (GPS/GNSS).