Improved Engineered Wood Fiber (EWF) Surfaces for Accessible Playgrounds Field Performance Testing: Final Report II

Installation of Test Surfaces

In accordance with standard EWF design and construction practice (Figure 2), the full depth surfaces were prepared to the same requirements needed for permanent playground surfaces. Our installation began on February 27, 2002 and was completed with bonded top surfaces within six weeks. The installation steps were:

1) Excavate area 380 mm (15 in.) in depth with a minimum of 1% grade to ensure proper drainage. All roots, stones, and vegetation were removed.

2) Place a diversion along the slope above the test area to assure no direct site drainage into the surfaced area.

3) Cover entire subgrade with one layer of geotextile. Overlap courses of geotextile by 125 mm (5 in.).

4) Cover the excavated surface to a 75 mm (3 in.) depth of washed 18 mm (¾-inch) stone.

5) Cover entire drainage bed with one layer of geotextile. Overlap courses of geotextile by 5 inches.

6) Spread wood fiber to a depth of 1.5 times the target depth.

7) Hand rake for a smooth finished surface.

8) Install retaining borders (15 mm thick x 100 mm wide plywood) between each pad.

9) Top Surface Preparation and Installation: (Assure temperatures are correct for this operation. Most stabilizing binders required 40 degrees F. for proper curing.)

a) Place the EWF to be stabilized into 60 liter (15 gallon) mixing bin. Measure the needed material by volume (1.5x the volume needed).

b) Measure EWF moisture content.

c) Measure the binder as a proportion of EWF dry weight.

d) Mix the EWF and binder using a mixing paddle.

e) If required, place the single layer of geotextile onto the EWF.

f) Immediately dump the resin/EWF mixture onto the target pad, spread with hand tools to even thickness and flatten with a 1.2 m x 1.2 m x 16 mm (4 ft. x 4 ft. x 5/8-inch) piece of plywood using firm pressure to bring the cushioning pad thickness to the full 0.3 m (12 in.) depth required for unbonded EWF.

Figure 2. Representational cross-section of the installed surfaces. Note that the EWF thickness includes the thickness of any stabilized EWF layer.