German to English Tech/Engineering Construction / Civil Engineering

This is described in a manual on concrete as a method for concreting under water.

Context:
Damit sich der Beton beim Betonieren nicht entmischt, sind besondere Betonierverfahren, wie das Benutzen von ortsfesten Trichtern (Kontraktorverfahren), notwendig.

Obviously a translation of this could be "contractor method" but I'm not sure whether this would identify the process in English... my hunch is that there a less literal translation that describes the method.

Thanks very much for your comments in advance