Establishing A Grade
If the grades are light, they should be
established by use of a telescope level. Most of the cheap levels are a
delusion. A stake driven flush with the surface of the ground at the
outlet becomes the starting point, and by its side should be driven a
witness stake. Every 100 feet along the line of the proposed drain and
laterals similar stakes should be driven. Their levels should then be
taken, and when the fall from the head of the system to the outlet is
known, the required cut at each 100-feet station is easily determined.
It may be necessary to reduce or increase the grade at some point to
get proper depth in a depression or to save cutting when passing
through a ridge.
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