I just removed a large plant that has been filling my main sewer line with roots. Under the plant there was a limestone slab with a cluster of small diameter pipes running down the center of it. The roots of the plant actually pulled a chunk of this limestone up with it. Should I be concerned? What would be its purpose? The pipes were totally blocked so whatever it was for I don' think its been working for a long time.
Here are some pics to show what I'm talking about http://www.flickr.com/photos/48537224@N05/?saved=1
Thanks in advance for any insight.