Regrading a Hillside for Solar Farm Construction

This question came up this week which I thought was a great use case for the RPS Slope Designer command - it really helped to solve the issues presented by the user.

The issue they have is that they are constructing a large solar farm project in undulating terrain, and they have issues when the slopes of the existing surface are greater than 10 degrees of slope - in those situations, the solar racking support piles, do not have sufficient adjustment to compensate for the steeper slopes, and the contractor has to take on stabilization methods to prepare the ground for the solar racks.

So in this case they provided a set of existing terrain contours for one section area of the solar farm, and requested our assistance to look at how you could remodel the surface contours to make the slopes less than 10 degrees over the entire site while trying to keep mass grading to a minimum and cut to fill volumes to a minimum.

In this case we can use the surface model properties to highlight areas of the existing surface that need to be regraded using the shade by slope range function. Once the areas for regrading have been identified, you can review the contours in those areas to determine the best course of action.

When you think about it, the shaded areas are really just areas where the contours are too close together because the slopes are too steep. So the fix to the problem on the face of it is to simply move the contours further apart in those areas to shallow the slopes - of course it is not that simple because by moving one contour away from its neighbor on one side moves it closer to its neighbor on the other side thereby increasing the steepness of the slope on one side and decreasing the slope on the other. It is a chain reaction that you need to identify which way you can push the contours (up slope or down slope) to an area where the contours are wider apart - thereby taking up the changes that you are trying to make without increasing the slope of any area to exceed the threshold of 10 degrees.

There is a degree of trial and error here of course, however the video shows the processes adopted to tweak the contours in small areas and how to redesign the surface slope in larger areas using the Slope Designer tool from Rockpile.

Slope Designer works really well for this process because you can select one contour as the origin, define the 10 degree slope and then select Range Parallel between a start and end point (the area of regrading) and then you can remodel the furthest contour elevation to check whether your estimate of where the slope adjustment needs to stretch to in order to regrade the surface. Once you establish the furthest contour reshape, you can then use the Slope Designer to compute the reshape of all the intermediate contours between the source and furthest contour. Then you use Break and Smart Join to create the new regrade contours and update the surface model to check that your slopes now meet your criteria of 10 degrees.

In the video we show you how to

  • Use the RPS Convert to Linestring command to filter line vertices to reduce the number of nodes in the source contours
  • Use Surface Properties - Shade by Slope Range to highlight the areas that require regrading
  • Use grips to tweak a contour using minor moves of the contour nodes
  • Use slope designer in Slope to Elevation mode using Range Parallel to re-compute the contours for the regrading process
  • Use Break command to break the existing and regrade contours before joining them back together again using RPS Smart Join
  • Use RPS Copy to Clipboard and RPS Paste commands to copy data from one project to another
  • Use surface modeling commands to build surfaces, trim surface edges, add edge breaklines
  • Use the Earthwork Report to compute regrade cut and fill volumes and to create a Cut Fill Map from the Isopach model
  • Visualize the regrade changes using Surface Slicer and 3D view commands

Regrading Area With Solar Panels and Cut Fill Map

Cut Fill Map with original contours (Gray) and Regrade Contours (Red)

Video shows you how

Pretty cool project to look at - thank you for raising the question