Inspection Chamber (IC) relocation

[BuBBleBee 0]

Chance upon this forum and would like to seek some advises/info on relocating of IC in the kitchen area of a semi-detached for a A&A/Recon.

What does it take to relocate the IC to outside of the house? Heard a few very different assessment, ranging from

a)  simply abandoning the current IC and routing the private sewer line to the new IC location and then connecting to the main (public) sewer line through a new joint,

b)  to having to keep the old IC and route the sewer line from the new IC location back to the old IC and out into the public sewer line (ie. still using the old IC ?!)

c)  same as (a) but where the new IC line connects to the public sewer line, have to build a new manhole for PUB ($$$)

Some of these are "required" by PUB as mentioned by some of the contractors.

For me (a) is of course the simplest and the preferred way. It also make more sense as there is no manhole at the current location where the existing IC connects to the public sewer line and that any post construction (or even pre) inspection will have to done using CCTV as required by PUB when one "touches" the sewer line.

For (b), it just does not make sense. Basically it is telling me that I cannot touch the existing public sewer line (make new connection and disconnect old line from it), and I have to keep the old IC functional and accessible for inspection. Then why would I want to relocate the current IC in the first place?!

Hope some one who has info on this or has gone through an IC relocation can share with me his or her experience.

Greatly appreciated, thanks

 

[snoozee 97]

relocating an IC is not a trivial matter as this involved the connecting of all the waste water outlets in your house to a single point (IC) and then from then connecting to the public sewer.

unless you are doing a full rebuilt where the new waste water outlets can be designed from scratch, I would say relocation an IC for an A&A or recon doesn't make sense especially if you are trying to minimize the amount of work.

currently all the waste water pipes (from all bathrooms, toilets, kitchen) are going to your last IC in your kitchen before a pipe connects it to the public sewer. if you want to abandon this IC, then you will need to find some way to route the waste water from all the waste water pipes in your house to somewhere else and this would mean digging up the floor in various parts of the house up to soil level to re-run the pipes. if i didn't remember wrongly, PUB requires the bottom of the IC to be at least 75cm down from the floor level (to prevent backflow) so imagine how much digging needs to be done if you want to relocate the IC and run new pipes.

PUB does allow for new connections to the public sewer with the requirement of post-CCTV survey being done to certify that the sewer is not damaged in any way after the construction. manhole is required for very specific scenarios and I don't think doing a new sewer connection will require one. do note that IC and manhole are different.

also,  is the public sewer within your land lot or outside? if inside, you will need to build an RC trench to protect the sewer (assuming there already isn't one) and you could try to plan to relocate the last IC in your kitchen (if you are willing to re-run all the waste water points). another consideration is where do you want to relocate the IC to? PUB required the connection from the last IC to the sewer to be a straight connection and with a minimum gradient. this will mean you cannot install the new IC wherever you want since the connection to the sewer needs to be considered based on where the sewer line is and how deep it is as well.

for my corner terrace, I will be relocating my IC to the side where it would be outside the house. I am doing this because I will be doing a new rebuilt and I need to build a RC trench for the sewer which is running through my back yard so might as well relocate the IC since the land is going to be dug up anyway to lay new waste water pipes.

 

 

[recharging 0]

On 6/17/2018 at 4:40 PM, snoozee said:

relocating an IC is not a trivial matter as this involved the connecting of all the waste water outlets in your house to a single point (IC) and then from then connecting to the public sewer.

unless you are doing a full rebuilt where the new waste water outlets can be designed from scratch, I would say relocation an IC for an A&A or recon doesn't make sense especially if you are trying to minimize the amount of work.

currently all the waste water pipes (from all bathrooms, toilets, kitchen) are going to your last IC in your kitchen before a pipe connects it to the public sewer. if you want to abandon this IC, then you will need to find some way to route the waste water from all the waste water pipes in your house to somewhere else and this would mean digging up the floor in various parts of the house up to soil level to re-run the pipes. if i didn't remember wrongly, PUB requires the bottom of the IC to be at least 75cm down from the floor level (to prevent backflow) so imagine how much digging needs to be done if you want to relocate the IC and run new pipes.

PUB does allow for new connections to the public sewer with the requirement of post-CCTV survey being done to certify that the sewer is not damaged in any way after the construction. manhole is required for very specific scenarios and I don't think doing a new sewer connection will require one. do note that IC and manhole are different.

also,  is the public sewer within your land lot or outside? if inside, you will need to build an RC trench to protect the sewer (assuming there already isn't one) and you could try to plan to relocate the last IC in your kitchen (if you are willing to re-run all the waste water points). another consideration is where do you want to relocate the IC to? PUB required the connection from the last IC to the sewer to be a straight connection and with a minimum gradient. this will mean you cannot install the new IC wherever you want since the connection to the sewer needs to be considered based on where the sewer line is and how deep it is as well.

for my corner terrace, I will be relocating my IC to the side where it would be outside the house. I am doing this because I will be doing a new rebuilt and I need to build a RC trench for the sewer which is running through my back yard so might as well relocate the IC since the land is going to be dug up anyway to lay new waste water pipes.

 

 

I have an identical situation. How long did this relocation approval take? Are you able to provide indicative costs? You can PM me.

[snoozee 97]

3 hours ago, recharging said:

I have an identical situation. How long did this relocation approval take? Are you able to provide indicative costs? You can PM me.

Approval is quite fast, at least in my case it was a matter of days for PUB to approve of the new drainage plans. 

Cost wise I don’t know as mine will be part of my house rebuilt. You will need to find a contractor to work out the costs if you are just doing an A&A or reconstruction. Just doing a CCTV survey will already cost at least 2k. So you add in the digging and laying of new waste water pipes, sealing of the old IC, creating a new last IC, joining the new last IC to the sewer, patching back of the floor which had been dug up, I think should be more then ten grand to do it.

[imzz 0]

Hi,

I am now stuck in similar situation. I am rebuilding a semi detached and My neighboring unit is sharing IC with me and the IC is located at my wet kitchen. After few exchanges between builder and architect, these are the proposal.

1) Since neighbour is using existing IC, no demolition. Only extension/alteration of existing IC so as not to disrupt the existing flow

2) Sewer line from main sewer to existing IC is broken to some repair work is required.

3) Building new IC (outside kitchen) is still advisable  for easier mainenance and due to the fact that sewer line is broken (???)

My questions are:

1) Do I really need a new IC if I am extending the existing IC? This will help me to save some cost. Since this IC cannot be removed and will be located in my wet kitchen, I might as well make full use of it.

2) Do I even need to extend the existing IC? Can I just let neighbour use the existing IC and I build a new IC and maintain a separate sewer system from them. If I do that I don't even need to repair the damaged sewer line?

 

Thanks,

 

[snoozee 97]

Imzz, ask your architect or builder to get the plumber in for discussion. The plumber will be the best person to give advise as they will know the regulations for sanitary requirements better.

My opinion is this. If the IC is shared by your neighbour, you cannot abandon it. If the sewer connection is broken, you will need to fix it else waste water will flow into the soil and cause issues.

unless you are willing to spend $$ to build another connection to the main sewer and then possibly let your neighbour use this new sewer connection as well then you can abandon the existing IC. However this also depends on whether the neighbour behind you allows you to dig up his back yard to do the new sewer connection or not (I assume the main sewer is running through your back neighbour’s house which is common in old estates)

There are quite a bit of rules and regulations on how sewers can be connected so best to get the plumber involved and this will also need submission to PUB for approval

[imzz 0]

The proposal was actually done up by the plumber. So the latest update I get is each house is only allowed 1 connection to the main sewer line. So have to fix the broken connection and reuse it. So the remaining cost effective solution for me is not to build another new IC, but expand on the existing IC so both me and my neighbour can use it. The plumber still have to study if this is feasible.

[snoozee 97]

Not sure if this would work. Depending on where the broken connection is located, you could possibly build a new IC at that broken part so that this IC serves your house and also is connected to the existing IC. So the new IC will become the last IC instead.  

[imzz 0]

I was told that no matter what existing IC needs to be altered its too low compare to the new floor level. This repair and alteration will cost 6k and its unexpected and not inside my contract

[snoozee 97]

Too low or too high relative to your new finished floor level? Unless you are changing your existing finished floor level by quite a bit, usually shouldn’t be an issue. Of cos if the level difference is already marginal then no choice. 

The bottom of the IC must be at a certain level from the finished floor level to prevent backflow. But this level must be high enough to provide a minimum gradient for the connection to the public sewer. 

Unfortunately this out of scope expense is something you have no choice but to fork out else you can’t move forward in your construction 

[3Cube 9]

Just an additional note on this discussion which affects the costing.

You need to carry out 2 CCTV scan. 1 Pre-construction & 1 Post-construction.

On top on this, you may need to set aside additional cost to reinstate possible damages during construction.

In my personal experience as a main building contractor, works done underground have high probability of damage to surrounding pipes, etc. This is due to years of wear & tear of existing sewer, manhole, etc.

[imzz 0]

I think its too low relative to the new floor finish. The site is already sloping down on the IC side and they would need to top up to ensure that it levels with the rest of the house. Good point on the pre con CCTV. Should have gotten it done. Architect initially suggest but somehow didn't propose to do it before actually construction start.

[snoozee 97]

officially, pre-con CCTV is no longer needed by PUB and normally if works does not involve sewer, I think no one would want to add on this expense as well.

the thing is when the site survey is done, did the topo contractors measure the invert level of the existing IC? if yes, then did someone pick up from the plans that the existing IC's invert level may be insufficient? for my house, the existing IC's invert level to FFL is only about 730mm which is below the required 750mm and I had raised this to my architect. but in the end as we are abandoning this IC, it didn't turn out to be a problem at all.

since you mentioned that the new floor level needs to be raised, would the new floor level be at least 750mm from the bottom of the IC to clear PUB's requirements?

[imzz 0]

Hm.. I am afraid your question is too technical for me. I am rather hands off and leave the supervision of the piling and structure work to my architect. I know a lot of horror stories about architect colluding with builders, but I trust that he is professional and he is a principal from a decent size firm. For pre and post con cctv, the quoation I got is 800 per survey. If demolition and piling increase the chances of damaging the sewer, then its definitely good to do it. The repair cost of the sewer is 3K+.

[3Cube 9]

Pre con sewer survey is best done for comparison to post con. It can sometime help to save cost on sewer lining repair (ie: when pre & post con report is same / similar no repair cost to be bear by owner) & help also to protect the owner's interest.

Let me try to put it another way:

Sewer lines are item own & maintain by authorities. When pre-con is not done for comparison, the authorities can order the owner to reinstate pay for carrying the sewer line repair by sewer repair contractor.

This is the same for pre conditional photographic survey to neighboring properties before any major construction of any form (ie: A&A, rebuilding, etc) to prevent unreasonable claims by neighbors on property damages due to construction.

Hope all can read between lines what I'm trying to convey.

Edited November 11, 2018 by 3Cube