Show me the plastic

I wondered how long, and how sustainable, the market shifts in petrochemical products might need to be before people would start chattering about digging up and recycling landfills. Seems odd that in 30-50 years time - or less if the peak oil advocates are right - old sites could become resources rather than embarrassments. Once we've harvested the methane and the anaerobic bacteria have done their stuff, we go back for the plastics. Not sure how the planning issues would be dealt with...well, not easily anyway. At least the pulverised fuel ash that we've gone back to recover for cement manufacture has been stockpiled on or near the coal-fired power stations where it was produced. Not too many folk live that close to those.