Hi Alexander,
admittedly this is the only hit I got, but it sure is an English language technical document in the field ...
[PDF] TARRANT COUNTY WATER CONTROL AND IMPROVEMENT DISTRICT NUMBER ONE ... - [ Traduire cette page ]Format de fichier: PDF/Adobe Acrobat - Afficher
Influent structure consisting of a heavy materials trap, bar screens and a Parshall fl ume (6-inch) to measure wastewater flow rates accurately. ...
www.twdb.state.tx.us/RWPG/rpgm_rpts/8483505a.pdf
I got all of 51 hits for "heavy material [in the singular] trap" ...