Equipment on deployed geosynthetics

Q: I’m hoping you can resolve a disagreement among coworkers regarding construction quality assurance (CQA). I’m asking what is published and/or your opinion. It involves traffic on geomembrane. Is it now industry standard to allow skid steers and/or ATVs to operate directly on a geomembrane? It is assumed no turning, spinning, etc. Technical specifications typically state 5 psi (34 kPa) on 1 foot (30.5 cm) of soil on top of the geomembrane. 

A: EPA/600/R-93/182–Section 3.3.4.1 “…using small pneumatic tire lifting units with maximum tire inflation pressure of 40 kPa (6 psi).” This suggests ATVs (not skid steers) with low ground contact pressure are acceptable. That written, such equipment should be accompanied with the following guidance: 

• A dedicated piece of equipment can be used only to deploy materials 
• The equipment cannot transition on and off deployed material (i.e., from soil to deployed geomembrane) 
• No sudden stops/starts 
• No tire spinning 
• Maximum tire pressure 6 psi (40 kPa) 
• Only smooth and clean tires are acceptable 
• 90° entrance and exits 
• No excessive turning 
• No driving over wrinkles 
• One person per vehicle 
• No vehicles on slopes 

Please note that some state regulations trump these recommendations. For instance, Michigan does not allow any equipment on deployed geosynthetics until 18 inches (45.7 cm) of cover soil is placed.