Understanding Property Benchmarks in Topographic Surveys

At Diamond Land Surveying, we’re proud to offer land surveying and related services to a wide range of clients, from homeowners to commercial building owners and even industry professionals like architects and engineers. We offer several specific solutions for this latter group, who often require precise measurements in numerous areas to complete their projects – one such solution is known as a topography survey, also called a topographic survey in many cases.

These surveys cover a few important points, and can be utilized by everyone from homeowners to contractors, landscapers and engineers to identify areas like property slope and contours on the property. Let’s go over their basic purposes, plus one area of measurement where you’ll have a choice between two metrics that are related but different in their final purposes.

property benchmarks topographic surveys

Topographic Surveys and Contour Lines

As we noted above, one of the primary purposes of a topographic survey is to show the contour lines of a given property. Contour lines refer to any areas where the land on the property slopes or otherwise changes elevation, vital information for several potential professionals or even for homeowners in many cases.

Generally speaking, the elevations that are shown in a topographic survey are given in relationship to a property benchmark. This benchmark is a base elevation level that has already been established on the property, serving as a basic foundation for any contours that show up in contrast to it.

Our upcoming sections will go over the types of reported elevation measures and which you should prioritize depending on your needs.

Assigned Elevation vs. Actual Elevation

When a topographic survey is being conducted, it can report the elevation of various contours on a property based on two similar but slightly different metrics:

  • Assigned elevations: In these situations, the surveyor themselves will establish the property benchmark elevation. A common choice here is 100 feet above sea level, though this obviously will vary in places like Utah with much higher elevations. In these cases, the elevations shown on a report are in relationship to the benchmark set by the surveyor.
  • Actual elevation: In other cases, GPS, state plane coordinates or even FEMA benchmarks will be used to set the property benchmark rather than the surveyor’s own choice. In these situations, the report will feature elevations that are the true number of feet above sea level based on the location of the benchmark.

Choosing Between Elevation Measures

It’s important to note that both those elevation metrics are accurate, and showcase any contours or changes in elevation properly. The decision on which to utilize is generally based on what it’s being used for, whether it’s personal use versus specific projects with a utility company or another government office. In the latter case, you generally want to go for actual elevation metrics where possible.

For more on topographic surveys and benchmark elevations, or to learn about any of our property survey services, speak to the staff at Diamond Land Surveying today.