Broken and cracked sewerage pipe in the garden - options?

[cammy0102]

Hi ladies/gents, I'm new to the forum. I'm after a bit of advice regarding my situation. I'm trying to pick the best option for repairing a damaged sewage pipe.


I have a ground floor garden flat in West London (period conversion) which I have been living for about year now. There 2 man holes in my garden - main one in the side return and the other manhole/interceptor at the back of the garden. These have been blocked a few times this year (tenant in the upstairs flat said they've been blocked multiple times in the last few years and that there's a structural problem) so I got a CCTV drain survey done using Dyno Rod. This highlighted a number of issues in the sewage pipe between the 2 manholes - couple of broken joints, root intrusion and crack in one place. According to the survey, the damage was most likely caused by ground movement and recommend silica lining to create a new path inside the pipe (pretty expensive quote provided).


We made a claim against our joint building insurance and this has been approved. The Insurance Loss Adjuster wanted a 2nd quote so I arranged arranged a company called Diamond Drains (also in West London) to inspect the drain problem and give me another quote, which came in a bit cheaper. He gave me 2 options - One to reline the pipe like with Dyno Rod quote and the other to replace the defective section (about 8m) of the pipe. I believe the replacement pipe material is plastic and this work will carry a one year guarantee whereas the reline option would come with a 10 year guarantee. Relining option is slightly more expensive but it's not a problem as the Loss adjuster reckons it's up to me who I choose for the repairs and how I get it done (obviously within the allowed limit plus I have to show invoice). I am new to all this stuff but to me, a replacement plastic pipe sounds like the better long term option.


I should mention that part of the pipe (about 5m) between the 2 manholes is under a newly laid patio and this section according to the drain survey is fine. The problems start about 7m from the main manhole. So if I go for the replacement option, part of the clay pipe between the 2 manholes will stay (the 5m section) and this will be connected to a plastic pipe that runs toward the interceptor manhole.


Since there is nothing in the garden at the moment (my Landscape gardner cleared it and prepared for the new lawn) digging is not an issue.


Here's an image of the layout to make more sense of what I'm talking about.


What option would you go for if you were in my situation?


PS: apparently I also have a problem with the interceptor manhole. The reason this one keeps getting blocked is due to the old design (U bend), I've been told. To rectify it, I'll have get it redesigned to have a straight pipe which will cost about 1300. I don't have the money at the moment but what are your thoughts on this? When I get the above work done, I'm going to ask the guys to pressure jet it and also have a look in the interceptor to see if there's anything in there that might be blocking it.


Thanks in advance for any input.

 

[cammy0102]

Well it wouldn't let me post the link to the image.

Basically there's an extension at the back and patio around it. Main manhole under this patio in the side return. The interceptor manhole about 13m away from it in the garden (back of it).

 

[joni os]

Biggest problem with interceptor is bung in rodding eye goes missing and then syphon fails to self clean. With syphon flushed clean and new bung to seal rodding eye manhole should perform as intended, without additional works.
Depth of manholes is not given but for depth not exceeding 1.5 metres my personal choice would be excavate and replace. Provided plastic pipe has 6" pea shingle surround laid in accordance with Building Regs. There is no reason not to expect 50 yrs plus of service life.
Other services, gas, water, BT etc. need locating prior to any machine excavation. Back in the late 60s, a couple of men from Cricklewood would have hand dug in a day, thinking £6 a shift was good money.

 

[Best]

Plastic sewer is best if done right and inexpensive, even allowing for new manholes.
Replace all clay sewer pipes you can, particularily any that could be later below concrete, etc areas.

 

[cammy0102]

Plastic sewer is best if done right and inexpensive, even allowing for new manholes.
Replace all clay sewer pipes you can, particularily any that could be later below concrete, etc areas.

I really don't want to break the new patio so I'm going to have to leave that bit of clay pipe intact and only replace the damaged section with plastic pipe.

Have you guys had any experience with relined sewage pipes? Do they last long?

Will having multiple joints in the new pipe (if I go for replacement) cause problems - there will be joints between clay-plastic, plastic-plastic, etc.

 

[cammy0102]

Biggest problem with interceptor is bung in rodding eye goes missing and then syphon fails to self clean. With syphon flushed clean and new bung to seal rodding eye manhole should perform as intended, without additional works.
Depth of manholes is not given but for depth not exceeding 1.5 metres my personal choice would be excavate and replace. Provided plastic pipe has 6" pea shingle surround laid in accordance with Building Regs. There is no reason not to expect 50 yrs plus of service life.
Other services, gas, water, BT etc. need locating prior to any machine excavation. Back in the late 60s, a couple of men from Cricklewood would have hand dug in a day, thinking £6 a shift was good money.

I think the depth is less than 1m.

I am not sure about the gravel around the plastic pipe (this wasn't specified) but I could ask the guy.

So everyone recommending replacement of the damaged section with a plastic pipe instead of relining option?

 

[joni os]

Relining for street works or deep pipelines, but for pipes in back yard, not exceeding 1 metre depth, excavate and relay is cheapest and best option.
Shingle surround necessary for proper support of plastic pipe. If your builder is unaware, use another builder/groundworker.
Special collars, Clay to plastic pipe, easily available.
This work should be notified to building control and inspected by them. This will involve a fee which should be recovered from insurance.

 

[snowhead]

Don't go the relining route.
I've seen about half a dozen done on commercial properties and I can't remember 1 that hasn't failed.

As above if it's accessible replace the pipe.

 

[Radioman]

Replacement every time if possible, joints are not an issue if done to building control spec. As said above, works are notifiable to building control who will inspect before the trench is backfilled. If your chosen contractor is unaware or reluctant get another contractor as BC cert will be needed if you sell the property or experience further issues. Also get hard copy of Public Liability insurance and phone insurers to make sure it is current just like the old bill do with car insurance. Also FYI contractor is liable for claims against his work for 6 years not 12 months. You might want to check https://www.businesscompanion.info/en/quick-guides/consumer-contracts/mixed-contracts

 

[oz-plumber]

Find out if the re-lining company is going to do the entire drain or just the damages sections.
Seen a few misconceptions about this over the years.

As for replacing the drain and leaving an old section under the patio, that would be asking for trouble in the future.
If the existing pipe has cracks and tree roots, then over time the section of pipe under the patio will have as well.