Jayhill:
Did you ever notice how sometimes, something someone says in passing makes you think "WHAT!"
Like for instance when you just said casually and offhandedly:
"One thing I have yet to do and that is to cap off where there was a toilet. Would this help?"
Which, correct me if I'm wrong, means that there was a toilet in that basement, someone removed the toilet and left the toilet drain wide open!
Yes sir, stuffing a 7-11 Super Big Gulp cup in that toilet drain pipe will go 99% of the way to removing the stench from your rental property's basement. Maybe not 99%, but my guess would be that MOST of the smell in the basement is from that open sewer pipe.
Re: OPEN TOILET DRAIN PIPE:
I've had apartments stay empty for long enough that the water in the toilet bowl evaporated and the apartment stunk like the dickens when I first opened the door to show the suite to prospective tenants.
If you haven't already done it, also pour a cup of water into every drain in the house too. The p-traps under the drains are for that very purpose, to trap a small amount of water in the drain pipe to serve as a physical barrier between the stench in the drain piping and the air in the living space you breathe.
Normally, the water in a toilet's toilet bowl serves the same function as the small amount of water in a drain's P-trap, but since you're saying the toilet bowl is no longer there, there's nothing stopping the sewer gas in your toilet drain pipe from wafting up into the air you breathe and making your house's basement smell just like a sewer. That is, you're basement will smell just like a sewer so long as that toilet drain pipe is left wide open, even if you never had a sewer back up.
Stick a Super Big Gulp Cup in that open toilet drain pipe, open up some windows in the place and give it a day to air out. Then see what it smells like in there. No matter how much you clean it's going to smell like a sewer as long as that toilet drain pipe has been left unplugged.
Re: Hiring a Flood and Fire Restoration Company:
Also, here's what I'd do. Open your yellow pages to Fire & Flood Restoration Services and phone around to several of them to find out whether they buy their chemicals locally from the places listed under Janitorial Equipment & Supply in your Yellow Pages or if they use their own chemicals.
If they buy them locally from a Janitorial Supply store, then you can go to that same place, buy the same stuff, and the person selling it to you will tell you where, when and how to use it. This is especially true if it's a family or privately run business because private businessmen make more of an effort to learn about the products they sell than their hired help. Either that, or Google the company that makes the stuff, go to their web site to get their phone number, invest in a $5 long distance phone card so you can phone them for 4.3 cents a minute and phone up that company to get advice on where, when and how to use their cleaning products. (Normally, each Janitorial Supply store will sell several different brands of cleaning chemicals, and truth be told, there are instances where some products work better than others, but most times the similarities outweigh the differences.) Also, the preceding assumes the local Fire and Flood Restoration Service company won't be willing to give you advice on how to use those products, and in all liklihood they will. If you talk to the owner or manager and just ask what he would use on the floors and walls in your situation, most likely he'll tell you what they use, how they use it and who they buy it from.
But, quite frankly, what you'll find is that in the cleaning industry, it's the people working at the Janitorial Supply stores that are really the modern day troubadores of the cleaning industry. That's because if a custodian has trouble cleaning something, about the only person he has to turn to for help will be the guy he buys his cleaning supplies from. That retailer, in turn may know of someone else who had the same problem, and will probably remember how he solved it if he did. With the retailers being involved in so many cleaning problems and subsequently usually finding out "what worked best", the retailers acquire a great deal of knowledge as well. Certainly, they will be well aware of how their customers use their own products, but they'll also know what works well in particular situations that don't often come up, like sewer back ups. I think you will find that same kind of thing to a lesser extent in every industry, but it's particularily true in the cleaning industry because cleaning professionals really only have their suppliers and the sales reps of the companies whose products they use to turn to for help. So, the retailers, especially the people that own their own businesses, will always be "in the loop" when problems are encountered and will learn as much as the pros on their solutions.
If the Flood and Fire Restoration Service you phone use their own cleaning chemicals, then they almost certainly sell their chemicals to their customers for regular maintenance and follow up, as well as customers who want to save money by doing what they can themselves. I'll bet my dollars to your donuts that if you buy the cleaning chemicals they say you need from them, they'll give you all the advice you want or need about how use those cleaners tossed in free of charge.
That is, you don't need to hire an Fire and Flood Restoration Company to get the information and chemicals you need to do a proper job cleaning your basement. If you follow the advice of people who do that work, and use the same cleaners they use, you'll get the same results.
But, plug the toilet drain pipe and it might smell like it's clean as a whistle already.
The rest is just my own ramblings...
I am not a professional carpet cleaner. But, I own a commercial carpet extractor, I use Chem-Spec products (which are popular in the carpet cleaning industry) and I do as good a job on the carpets in my building as any pro would. And, I've never felt that any of the carpet cleaning contractors I've ever phoned up to get advice from ever "withheld" information from me because he knew he wouldn't make anything off me. In fact I've found the opposite. I've found them to be more than willing to share their knowledge with me, just as the pros in here share their knowledge with us. I've found every person in the cleaning industry willing to share their knowledge and experience with me if they had the time to do so, so I think all you need is to contact some of the places that do fire and flood restoration work and you'll be on your way before you know it.