]
Fig. 40 - CROSS-SECTION OF DITCH (FILLED), WITH FURROW AT EACH SIDE.
In order that the silt-basins may be examined, and their accumulations of
earth removed, during the early action of the drains, those parts of the
ditches which are above them may be left open, care being taken, by
cutting surface ditches around them, to prevent the entrance of water from
above. During this time the covers of the basins should be kept on, and
should be covered with inverted sods to keep loose dirt from getting into
them.
*Collecting the Water (C)f Springs.*--The lateral which connects with the
main drain, _A_, (Fig. 21,) at the point _m_, and which is to take the
water of the spring at the head of the brook, should not be opened until
the main has been completed and filled into the silt-basin,--the brook
having, meantime, been carried over the other ditches in wooden troughs.
This lateral may now be made in the following way: Dig down to the tile of
the main, and carry the lateral ditch back, a distance of ten feet. In the
bottom of this, place a wooden trough, at least six feet long, laid at
such depth that its channel shall be on the exact grade required for
laying the tiles, and lay long straw, (held down by weights,) lengthwise
within it. Make an opening in the tile of the main and connect the trough
with it. The straw will prevent any coarse particles of earth from being
carried into the tile, and the flow of the water will be sufficient to
carry on to the silt-basin any finer matters.
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