Mainline backing up

[robcanuck]

We moved into an older home (mid 1950's) last summer and have had two back-ups. On both occasions water was coming up the floor drain in the basement. I had a CCTV scan of the pipes done and have narrowed the problem to a section of the main pipe approximately 22 feet from the main stack. The exterior wall of the house is approximately 21 feet from the main stack and there is a cleanout right before the pipes exit from the home.

It looks like there are potentially weaping tile connections at 22 feet and the cleanout at 21 feet. It seems like the connection may be misaligned which could be resulting in the clogging. The toilet paper and stuff remaining in the pipes suggest this may be case.

I would appreciate any input anyone has as I want to tackle this one and for all! Thank you.

Here are some photos:



And here is the CCTV scan:
http://www.youtube.com/watch?v=N9cChO0P6yA&feature=youtu.be

 

[hj]

Black and white cameras do not give a lot of definition, but those pictures imply a reduction in pipe size.

 

[Sponsor]

 

[robcanuck]

From the photos, it does appear that way. Although the video perhaps suggests a lesser decrease than the photos. If there is a small reduction in pipe size, what options do I have if this pipe is running directly under my foundation wall (short of digging up from front yard). Should I put a floating drain cover on the floor drain so that if it happens again the water comes up the shower drain instead (the shower can hold about 80 litres of water - it is a Kerdi system)?

Would enzymes be good to put down the drain once in a while to maintain the drain?

Any other suggestions?