Assertion: septic tank's bottom | /r/HasProperty | forming sludge
Facets:
Source sentences:
text: Its job is to hold the wastewater long enough for solids to settle to the bottom (forming sludge) and for the oil and grease to float to the top (as scum).
text: In the tank, the heaviest matter settles to the bottom (forming sludge) and the lighter matter (scum) floats on top of a somewhat clear liquid called effluent.