I own rental property in Chapel Hill, NC, built in 1970 on a concrete slab. It is surrounded by ancient oak trees. Last fall our renters complained about rodents in the toilets. After a plumber ran a lighted instrument down the drain into the pipes, he discovered cracks that are allowing the rodents to enter. He could actually see them darting around!! He says we will have to rip out the parking area, remove the trees, and replace all the pipes - to the cost of $10,000 starting, with no guarantees about the upward costs! Please, is there anything else we can do? I think we saw a TOH show on running some sort of sleeve into the plumbing that repaired the crack without replacing everything. HELP!!!!