Loose-Fill Depth After a Windy Weekend
A school playground uses engineered wood fiber (EWF) over a geotextile membrane. The equipment includes a 2.7 m high deck with a slide and a swing bay with belt seats. The maintenance log shows the last top-up was 14 months ago. After a windy weekend and heavy rain, staff report the EWF looks thin near the slide exit and under the swings, with bare membrane visible in two patches near the slide. A staff member measures depth at three points with a tape and gets 200 mm, 180 mm, and 150 mm. The manufacturer's specification for this equipment calls for 300 mm of EWF to achieve the required critical fall height. The school asks whether they can simply rake material from the open play area to fill the thin spots and reopen.
1. Assess the measured depths against the requirement and judge whether raking material from the open area is an acceptable fix.
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All three measurements (200, 180, 150 mm) are below the specified 300 mm, and the thinnest reading is at the slide exit - a high-traffic, high-fall-energy location. Bare membrane visible near the slide means the protective layer is locally absent.
Raking from the open play area is not acceptable as the sole fix:
- It simply relocates the deficit; the donor area may drop below its own required depth.
- EWF compacts and displaces under use, so redistribution without replenishment does not restore the specified depth.
- The bare patches indicate displacement and possible membrane exposure; localized topping-up must restore full specified depth across the entire use zone, not just visually cover bare spots.
Correct action: Close the affected equipment until depth is restored to the specified 300 mm across all use zones using new EWF, then re-measure at multiple points (including slide exit and under swings). Record depths and date. Investigate why a 14-month interval with visible displacement went unaddressed - the inspection frequency is inadequate.
2. Identify the maintenance and inspection failures this situation reveals and propose corrective actions.
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Failures:
- Inspection frequency - 14 months without top-up despite known displacement zones (slide exit, under swings) is too infrequent. Loose-fill in high-traffic zones needs routine depth checks, more often than annual.
- Measurement method - a tape at three points is a start, but depth must be checked at multiple points in every use zone and at the equipment's fall-height-critical locations, not just where it 'looks thin.'
- Documentation - the log should record depth readings, locations, and corrective actions.
- Membrane exposure - bare membrane is a red flag for both insufficient depth and possible damage; inspect the membrane.
Corrective actions: close equipment; replenish to 300 mm with new EWF; re-measure and document; increase inspection frequency for high-traffic zones; train staff on proper depth measurement; review whether the geotextile is intact where exposed.