For weeks, the Union soldiers worked on the canal. They dug through mud and wet clay.

几个星期以来，北方士兵一直在挖运河，他们不断地挖掘泥浆和粘土，许多人得病死了。

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The canal would soon fill up with mud if not regularly dredged.

这条运河如果不经常疏浚，就会淤塞。

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Since then they have put in more than 2, 500 days of voluntary work, moving an estimated 300, 000 tonnes of mud from the route of the canal and its locks.

BBC: Barge on a canal

So extensive were the wet-season mudslides that in some years more mud and rock fell back into the canal than had been taken out in the first place.

ECONOMIST: The Panama Canal

The French had spent many years and thousands of lives trying to build a canal to connect the Atlantic and Pacific oceans and had been defeated by year-round heavy rains in mountainous mud, deadly diseases, and impossible expenses.

FORBES: The Panama Canal: When the U.S. Flexes Its Creative Muscle