This photograph shows the layer of gravel under the liner in a bunker that the sand has been removed from. This is the gravel that will be sprayed with an adhesive that will bind the gravel into a solid mass while allowing to be porous. This means water will move readily through the bunkers. It is imperative we keep this gravel clean so no soil or sand contaminates it, clogging pore space that water would otherwise move through. The adhesive eliminates the need for the liner. The liner is effective but they often tear and rip and they become clogged as well which slows drainage.