What kind of backflow prevention would prevent this amount of pressure, and why should an owner have to pay to shield his foundation from this "Toxic Waste".It seems like the city should not be maintaining a "Public Nuisance" of "Toxic Waste" that bursts through foundations.It seems like the city should remedy this immediately and also pay for damages to the building.Retrofitting one way waste vales between the units might also be a positive to prevent inter-unit backups like this (on your own dime).But the city should not be blasting toxic waste through foundations--(how much pressure that must be).Toxic waste = AIDS and other similar....Did any other building owners on the street get hit this hard--maybe group together and get this solved.Good Luck with this.

I have some knowledge in the toolbox, but I got completely wiped out in 2010-2011 due to poor planning and a toxic partnership that I should have addressed sooner.

They were probably irritated they weren't able to get the same terms as the first deal, not just with us but with any other lender. 

Doing it in one step is far less irritating.

IMHO, your first job is to get out of the current "toxic" position.

I was happy to help the new buyer so the transaction would go smoothly but it was herding cats trying to get her the guest's info, pricing, respond to irritated guests who had to go through extra steps of rebooking with new owner, etc. 

Which is hire a professional to remove the toxic material.Not cover it up with drywall, not do a home test kit, not scrape it off quickly and hope that no one finds out, not put yourself at risk, not look for a loophole in the laws.This crap is what gives us flippers a bad reputation.

It is quote toxic and it sort of looks like pink soap. 

There are agents and investors in my area that fire off incredibly low offers sight unseen and all they do is irritate the seller who then won’t work with you no matter what.  

A consistent and routine collection effort is known to get results if not completely irritate the heck out of this thief who robbed you of 7+ months of rent/damages.And, document everything to include that she abandoned the property and photograph/document the damages.