CSLB C-27 Landscaping ContractorSite Preparation and DrainageHard
A landscape contractor is overseeing the compaction of a subgrade for a new artificial turf installation. The project specifications require a minimum of 95% compaction (Modified Proctor). Why is achieving this specific compaction level critical for artificial turf?
- ATo promote rapid drainage through the compacted layer.
- BTo ensure uniform firmness and prevent settling or undulations.
- CTo increase the soil's organic matter content for turf health.
- DTo maximize water retention for the turf's sub-base.
Show answer & explanationAnswer & explanation
Correct answer: B. To ensure uniform firmness and prevent settling or undulations.
Achieving 95% Modified Proctor compaction ensures the subgrade is uniformly dense and stable. This prevents differential settling, which could lead to uneven surfaces, undulations, or 'soft spots' in the artificial turf, compromising its playability, aesthetics, and longevity.
Why the other options are wrong
- A. While some drainage occurs, the primary goal of subgrade compaction for artificial turf is stability, not rapid drainage through the compacted layer itself (which is often achieved by the aggregate layers above).
- C. Compaction does not increase organic matter; in fact, it can be detrimental to soil biology if not managed properly. Artificial turf doesn't rely on soil organic matter for 'health' in the same way natural grass does.
- D. Compaction reduces void space, thus decreasing water retention. Artificial turf sub-bases prioritize drainage, not retention.
Artificial Turf Subgrade Compaction
The process of increasing the density of the native soil beneath the aggregate layers of an artificial turf system, typically to 95% Modified Proctor, to provide a stable and uniform foundation.
- Prevents settling and undulations in the turf.
- Ensures consistent playability and aesthetics.
- Critical for long-term system integrity.
Memory trick: Compacted ground, no soft spots found, for turf so green, a perfect scene.