- Standard excavating, grading and compaction equipment should be used to grade and compact the area to be protected and to excavate anchor, flank and toe trenches.
- Vegetation and obstructions, such as roots and projecting stones, should be removed.
- Unsuitable soils should be removed and replaced with select material and compacted according to contract specifications.
- Draglines and bulldozers are suitable for rough grading, but fine grading shall be performed with backhoe, grader or similar equipment.
- Underwater installation may be facilitated if a leveling course of granular material is placed prior to fabric form.
- Establish Starting Point & Alignment Lines
- It is custom to work from upstream to downstream
- Prevents construction flows from undermining or bunching fabric
- String lines are set both parallel and perpendicular to slope in an offset manor
- Placement of first fabric panel
- Panels are identified for placement according to fabrication drawings
- Panels are accordion folded and then rolled
- Panels should be extended into position by pulling the leading side of panel
- Panels should be placed loosely and extra form contraction should be gathered into temporary tucks at each seam and at top of slope
- Placement of remaining fabric panels
- If panels are sewn together in the field, the succeeding panel is place atop the last mil width.
- Panels are then joined together edge-to-edge, by sewing the top layers and bottom layers independently
- If panels are joined together with pre-installed zippers, the succeeding panel is placed adjacent to last mil width
Fine Aggregate Pumping
- Fine aggregate concrete is pumped into the forms by inserting a 2”Ø grout hose through a small slit in the top layer of fabric
- In order to control the position and prevent sliding, concrete is either pumped into the portion of the panel that has been placed into the anchor trench or is secured with sand bags
- A tight seal is made by wrapping nonwoven fabric around the pipe, as well as closing the slit once pumping has discontinued
- First section of panel is left un-pumped to prevent fabric from sliding into flank trench
- Starting in the second section, the injection pipe should be inserted inside the first baffle and at a distance from the toe as determined by slope angle and fabric type
- The flow of concrete should always be directed toward toe of slope
- Spacing of injection ports is also determine by slope angle and fabric type
- As the fabric is being pumped the panel will contract causing a tightening of the form
- As one baffled section is fully inflated, contractor will repeat theses steps along the alignment of the plans until entire lining has been pumped
- Each individual baffle sewn into the fabric form will act as a cold joint, allowing contractor to control the work flow
concrete has cured (approximately 24 hours), toe and flank trenches can be
backfilled and compacted
- As much as 10% contraction in each direction
- Maximum single panel size approximately 5,000 S.F.
- Maximum pumping speed approximately 15 yd3/hour
- Never use a boom pump. Always a ground pump
- Maximum pumping distance approximately 1,500 linear feet
- Typical crew size is 3 to 4 laborers and a supervisor