Kev sib sau ua ke corrugated culvert yeeb nkab yog ua los ntawm ob peb daim ntawm corrugated daim hlau tsau nrog bolts thiab ceev, nrog nyias daim hlau, lub teeb yuag, yooj yim thauj thiab khaws cia, txheej txheem kev tsim kho yooj yim, yooj yim rau nruab rau ntawm qhov chaw, daws qhov teeb meem ntawm destructio ...