Ko te nuinga o te waa ka whakamahia hei apitihanga keri ka mau ki te peere hopu ina he nui rawa te wai, he paru kaore e pai mo te keri.Ka peia e te punaha hydraulic excavator, tetahi teihana waipēhi motuhake ranei ki te pupuhi i te onepu, te paru paru me etahi atu.