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CNKS is right that your first stop should be the local NRCS office. Except it's Natural Resources Conservation Service, not "National". The NRCS can tell you about proper terrace design for your application. A critical item is that the terraces must be spaced close enough to handle a heavy rainfall without overflowing. You may have to put in several terraces, depending on the size of your field. My Dad built a few hundred miles of terraces in his lifetime. He surveyed most of them himself, and I got to carry the rod for him a good portion of the time. If your terrace is very long, you will need a better-than-average level or transit. An error that would only be a fraction of an inch for something the size of a house will add up to several feet on a long terrace. Also, the distance means that you need quite a bit more magnification than a typical transit has. My dad always used a Leitz autolevel that had about 32X magnification. Once you have your terrace spacing, the actual surveying is simple. Give your helper a handful of flags and a stadia rod, and have him start walking the general contour of the terrace. Every hundred feet or so, have him stop and check the stadia rod to see if he needs to go up or down. Just wave up or down to tell him where to go. When he's back on the contour, have him set a flag and go on to the next shot.
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