A colleague of mine earlier in the year did a 200ha 2m survey of a farm in Mexico in 2.5 days…got back to the car loaded up the points onto his laptop and then hooked onto the internet via his 3G stick and posted the points to me….the results can be found here (http://picasaweb.google.com/lh/photo/gg_32Jr5ITq2owOSVqIg9w?feat=directlink)….

I should add that the most important thing to survey when intending to do cut & fill earthworks is to survey not using the grid method but along ‘tops and toes’.

Grid surveying using the method Bill has described is something I did back when I started the Permaculture journey and our 1st job financed a dumpy level. My partner at the time, Michael Heenan (also my brother in law) and I surveyed a clients undulating property and had a lot of fun doing it but boy it was a pain….important thing was that we missed so much of the actual topography as a result of taking ’shots’ on the grid and not on the landscape tops and toes.

Our intention is to use this method to give us a better than government map topo map (often 10-50m contours!) using relatively cheap and available equipment. We can then get a better idea of the patterns of the landscape and design a plan accordingly.

At the end of the day however the old adage of ‘the map is not the territory’ comes in and we still use a design as a guide which then informs us as to a set out which is based on the land on which we stand and measure accordingly.

Best thing to do is to know all of the basics, which includes the method Bill described, as machines do fail and we have to fall back on other techniques occasionally.

All the best,

Darren

If you want to look at the errors, change the vertical values at a point, and re-compute the volume, looking at the differences. A change in horizontal location will cause smaller errors than changes in a vertical value, if the surface is not very steep.

If you can get enough hose, you can do the leveling with the water level (bunyip level, hose level, water level, or hypsometer), but an optical level and staff/rod or laser level and staff/rod can be a lot quicker and easier, especially if the ground is reasonably level.

The advantage of a regular square grid is that the computations are much easier. You can do it easily in Excel, or on paper, but if your points are irregular, you introduce a lot of computational overhead, with the chance of significant gross errors.

If you are looking at a low-tech solution, keep it simple all the way. Don’t complicate things unnecessarily, and just because there are a few high-tech pieces of gear in the overall system doesn’t mean that the errors are any less. They just hide differently. Computing volumes has a fairly high error potential, simply because you can’t measure every point, so you are looking to get the result to within 1-2 truckloads of dirt, 10-20 m^3 or yd^3.