Shu and I visited my cousin in northern Wisconsin this weekend, and we heard a phrase we hadn't heard before, borrow pit, to mean, "an excavation in which material is removed to be fill for another site." We wondered if it was a regional phrase? Have you heard it?
I'd never heard the term either, so I looked it up in the Dictionary of American Regional English. Borrow pit is a variant of barrow pit (probably by folk etymology). It occurs mainly in the western USA, but there are some citations from the Midwest. It is first cited from 1931, but a 1950 citation has more information:
Barrow-pit is common in road-making, to mean the dtich or excavation beside a roadway ... The ditch by the side of an ungraded road is called 'bar pit,' 'borrow pit,' 'barrow pit,' 'bar ditch,' 'borrow ditch,' 'barrow ditch,' 'grader ditch,' and 'gutter.'
It goes on to say that some informants connect barrow with wheelbarrow (used to carry away the dirt). The term pit is more frequent than ditch or gutter.