Umbala ovumayo ukufakwa phansi-ugcina ibhalansi yendawo ezungezile Umbala waphansi wokuvikelwa kwemvelo ovunyelekayo, owaziwa nangokuthi ukhonkolo omahhadlahhadla ombozwe ungqimba oluncane lukasimende, iqoqo kanye nokunamathisela usimende okuboshelwe komunye nomunye ukuze kwakheke ukusabalalisa okufanayo kwembotshana.
Ukugcinwa kwebhalansi yemvelo yombala wokuvikelwa kwemvelo okwazi ukungena phansi, owaziwa nangokuthi "ukhonkolo onama-porous", ebusweni be-aggregate emahhadla embozwe ungqimba oluncane lukasimende, i-aggregate kanye nokunamathisela usimende okuboshelwe komunye nomunye ukuze kwakhiwe ukusabalalisa okufanayo kwezimbobo esakhiweni sezinyosi, ngakho-ke inokungena komoya, amanzi ahlanzekile, amandla okuphakamisa amanzi kanye nesisindo esincane. ukuqeda izingozi zokungcoliswa kwemvelo njengezinhlanganisela zikawoyela phansi. Iwumsebenzi omuhle kakhulu wokugandaya ukuze kugcinwe ibhalansi yemvelo yemvelo. Iphansi elivumela ukungena ngombala lisebenza kuma-pavements, ezigcawini zomphakathi, ezindaweni zokupaka izimoto ezivulekile, emigwaqweni yasemapaki, emigwaqweni yabahamba ngezinyawo, emigwaqweni yokuhlala kanye neyasegcekeni lomphakathi njalo njalo.
