Hi, you could use steel sheet as suggested but if the collars already in place why not just by some good quality underaly with your liner. This wont rot and will be thick enough to stop the rocks underneath ripping the liner. www.flexibleliningproducts.com has a good range of butly liners and polyfelt underlay, not a bad price either.
Hope this helps.
Posted on Aug 6, 2007, 5:46 PM from IP address 82.38.193.186