quality management system certification

(1) Investigate the landscape image, water depth, water temperature, flow rate and other environment of the operation area. It can be operated only when the wind force on the water surface is less tha

1. Underwater search: two search team members in each group enter the water in the order planned in advance. The team member who arrives at the bottom table first must wait until another team member a

Dredging is an underwater earthwork excavation project that uses manpower or machinery to dredge, expand or excavate deep rivers, lakes and other waters. For a long time, channel dredging has been an