Installation Guideline: Woven Separation/Stabilization Geofabric

Geofabric Placement

  1. Clear all trees and brush from the site and all vegetation from the subgrade.
  2. Excavate and replace pockets of very weak or pumping soils with granular fill.
  3. Smooth and level subgrade by removing depression or humps by grading.
  4. Place the geofabric directly on the prepared subgrade. Install the rolls in the direction shown on the project plans to insure the materials principal strength is correctly oriented. Roll the geofabric out as flat and tight as possible with no folds.
  5. Adjust the geofabric so that the left and right limits are situated as noted on the project plans.
  6. Overlap adjacent rolls as indicated in the specifications, plans, per manufacturer's recommendations or contact the site engineer.
  7. In lieu of specific overlap instruction, please use a minimum of 12" - 18".
  8. Soil CBR will determine if overlapping or sewing is the correct option. AASHTO offers these general guidelines for sewing versus overlapping:
    Soil CBR > 3    Minimum overlaps of 0.3 - 0.45 meters
    Soil CBR 1-3    Minimum overlaps of 0.6 - 1.00 meters
    Soil CBR < 0.5 Must be sewn

Fill Placement

  1. Secure the geofabric in place with pins, staples, piles of soil, granular cover material or other suitable means to avoid shifting or movement during fill placement.
  2. Loosely place fill directly on the geofabric in 8" - 12" lifts. For very weak subgrades, 18" or thicker lifts may be required. Consult with the project engineer for correct lift thickness.
  3. Rubber tired vehicles and trucks may drive on the uncovered geofabric at speeds less than 10 mph. Avoid sharp turns or sudden stops.
  4. If damage occurs, refer to the manufacturer's repair instruction or consult the project engineer.
  5. Once the project engineer has determined a stable working platform has been obtained, compact fill to 95% of standard proctor density at a moisture content within 3% of optimum.

Repair

  1. In lieu of specific project guidelines, overlap damaged geofabric by a minimum of 36" in all directions.

Storage

  1. Geofabric rolls are wrapped in a UV protective cover.
  2. Contractor should insure rolls are adequately protected from moisture.
  3. If stored outdoors, the geotextile should be elevated from the ground and covered with a tarpaulin or opaque plastic.