6/7/2017 7:06 AM
I've become a bit of an expert on these since I'm involved with one of them. Full disclosure as well as still being a superintendent, I import Blinder Bunker to the US from the UK.
Hopefully this helps answer the original question:
Each product has its merits, you'll need to research them (ie talk to those who have them) to decide which is best. Since it was mentioned, I'll cover Klingstone first. It is a nice product but it does not provide a drainage layer - it prevents soil contamination. Some like this as it prevents the subsoil from washing so there is no risk of contamination. Ie it basically creates a tub to hold the sand and keep it clean. There is some concern about what happens under the porous liners but at least of them has a spec to help prevent any issues.
I'm not 100% sure about the Linebacker liner but I believe it is somewhat similar in concept to Klingstone.
The others provide a porous layer for the water to run through. This increases drainage volume and prevents the sand filling up with water which greatly reduces to eliminates washouts. They are broken into two categories - solid and flexible.
The solid ones are Better Billy Bunker (sprayed stone), Capillary Concrete (porous concrete) and Matrix (porous asphalt). The flexible one is Blinder Bunker (crumb rubber). All these products have all been around since 2008 or so - at least in trial form. Porous Pave is new to the bunker business and a sort of Hybrid of Blinder and Better Billy Bunker. All of these products provide a seamless drainage layer.
These products will create a perched water table just like a USGA green as you have a finer material over a coarse one. Just like in a green situation the sand needs to be speced to bridge the liner also to ensure it doesn't block it up. The sand will need to be tested with the liner to see what it's release curve is. Depending on that, the depth of the sand may need to be modified to ensure it releases the water so you don't get algae etc. The perched water can also benefit as it can be used to manage how much water is held so that the sand doesn't dry down too much either. Since these products are porous they are designed to go right over the drain lines.
These liners can only work provided the bunker is designed properly. Ideally the less water entering the bunker the better and the slopes of the faces should always be less than the angle of repose of the sand as if they are greater then nothing can keep the sand up on the faces.
Depending on the bunker design and native soil conditions the bunker may not need a liner, so these are not for everyone but are great tools in reducing the cost of long term bunker maintenance.