A note on the limits of this page before anything else.
Two answers in FES’s own reference material defer to a Filling and Installation Manual that has not been issued. That document is the source for detailed procedure, sequences, and tolerances.
What follows is the principle level, which the answer bank does support. It is not a method statement, and it is not a substitute for the manual or for the engineering team on a specific job. Where a number would normally appear, it is absent on purpose.
The setup
A filling frame or hopper. The bank covers whether one is needed to load the bags evenly, and evenness is the point: a unit loaded to one side sits and lifts unevenly, and it does not sit correctly when placed.
Stockpile position. How close the aggregate stockpile should be to the filling area is one of the bank’s questions. The practical driver is cycle time — every metre between stockpile and frame is repeated for every unit — balanced against room to work safely.
Staging space. For empty units, aggregate, the filling operation, and lifting. See site access and staging.
Ground bearing. Under the filling and lifting equipment, checked rather than assumed. The bank covers this.
The sequence, at principle level
The bank describes a sequence for loading an empty bag onto the filling frame. The principles it establishes:
Mount the unit so it is held open and square. A unit that is not properly presented fills unevenly.
Keep the mesh and lifting ropes clear and untwisted. The bank addresses this specifically, because a twisted rope or a rope caught under the fill is a lifting problem discovered at the worst moment. See lifting and rigging.
Fill in a controlled manner. Dropping stone from height into a unit concentrates impact on the mesh. Controlled loading is gentler on a component that has to last decades.
Fill to the approved weight or volume, checked, not judged by eye. The bank covers how fill volume is checked during production.
Secure the opening once the approved fill is reached. The bank covers how this is done.
Complete the pre-lift checks before the unit leaves the frame.
Common mistakes the principles are guarding against
Uneven loading. Produces a unit that hangs badly, sits badly, and stresses the mesh and rigging asymmetrically.
Ropes trapped or twisted. The most consequential, because it is a lifting problem.
Overfilling. Changes the unit’s shape and dimensions and stresses the mesh.
Underfilling. A lighter unit is a less stable unit, and it will not match the layout’s assumptions about coverage and stack height.
Impact from height during filling. Cumulative damage to the mesh before the unit has done any work.
Wrong material. Undersized fines that will migrate out, or flat and elongated pieces that bridge and leave voids. See fill stone selection.
No production record. The as-built matters for inspection later, and quantities matter for the claim if this is emergency work. See documenting emergency work for claims.
Handling a filled unit
The bank addresses whether a filled unit can be dragged a short distance across the staging area. It is the kind of question that gets answered informally on site and should not be.
The general principle: a filled unit is designed to be lifted, and dragging it across ground abrades the mesh on the underside where nobody will inspect it. Where handling has to happen, it should be a decision rather than a habit.
What is not on this page
- Step-by-step method statement
- Fill weight and volume figures per size
- Filled-weight tolerances
- Maximum drop distance during filling
- Frame and hopper specifications
Those belong in the manual and the data sheet. Neither has been issued, and the answer bank defers to both. Rather than fill the gap with plausible-sounding procedure, this page names it.
If you are planning a filling operation, the engineering team can give you the current position for your bag size and site. Send the details through the quote form, or call if the work is imminent.
Where to go next
- Fill stone selection
- Lifting and rigging
- Equipment selection
- Site access and staging
- The rock bag FAQ for the full filling and placement section
- The installation hub for the rest