Inner City Sewer Install - What does a potential homeowner or builder need to know
Sewer install is quite literally one of the most important features of a new home and should be a great comfort to the new owner than they will be getting a brand new system connected to an existing 50-70 year old piece of City infrastructure. A terrifying mess will be a guaranteed outcome if this work is done poorly.
Due to the sensitive nature of the work, involving shutting down streets and digging up the City owned roads and sidewalks, only indemnified contractors can do this work. The work is a real technical specialty, and the handful of indemnified crews have all the big toys to go along with this massive and time sensitive undertaking.
This brand new excavator was recently purchased by the owners at Precision Underground, at a cost of $190,000. This purchase was motivated by the failed $10,000 turbo unit in the old machine, and the pressure to install 170 sewer systems per season means down time is not acceptable.
In addition to the costly gear, the indemnified crews have a certain amount of pricing power over any client that needs the work done. During a 'boom' year, expect to pay a significant premium for this work. We have had the pleasure of hiring Precision Underground Services for the last few jobs we have done, one of the best indemnified crews doing this work in Canada.
To complete the job, a significant amount of work needs to be done in advance by the builder. This all comes at great cost as you will soon see.
1. Get a grade slip and hire the crew - the grade slip is provided once a DP is submitted to the city. The grade slip provides the information that is used to quote the job (depth of sewer). You can do some advance scouting here but basically you are at the mercy here of what the grade slip says. The job can be quoted now, this time we did not bother getting multiple bids (will explain why later).
2. Pay the asphalt degradation fee - this will cost between $1900 and $6000. We got off lucky this time because we are digging in an old road that hasn't been repaved recently. Our next job we are not so lucky...
3. Pay the $4250 water shutoff fee. This is the good news, you can get this back by doing the service kill, (which we have now done today - great for us to get that deposit back because we have another to pay soon).
4. Demolish the site and dig the basement. Pouring the basement and building the house may be necessary here if the indemnified crew can't get to you right away (often these crews have a multi month backlog).
5. We chose to go ahead with the install before pouring our basement because the winter season is upon us and sewer work largely shuts down. Cutting through frost is very difficult as well as properly repairing the road. This proved to be extremely beneficial. By opening up the street we found that the sewer was just deep enough to allow us to gravity drain the basement plumbing, saving $2500 plus major aggravation on site. Using the standard technique, the sewer would have been stubbed out to the property line and connected later, and lack of detailed measurements would have necessitated a higher pipe and lift stations.
6. Work is done following a similar methodology which is shown in the photos below
dig up the street and kill the old service for the sanitary water. This was being done as we arrived to the job site. Fortunately this crew starts work while builders are still in bed
Next the street is trenched for the new water lines to be run to the basement of the house. The lines are 1 inch pex pipe and must be 2.3 M deep to avoid frost issue.
Note the shoring boards are used to prevent cave ins while trenching. The crew has a genius system where the bracing pipes are charged with compressed air and quickly create a safe work zone. the lower of the two braces is removed once a bed of gravel is laid to bed the new lines.
Once the trench is prepared the water lines go in.
The vertical pipes show the water shutoff valves. These are barely visible at the back of the frame.
More gravel is added and the sewer pipes are laid according to the proper slope of 3 inch per length of pipe.
At this point the City inspector will be called to make sure the work is going according to the many rules of how this job must be done. Not surprisingly, the work is passed quickly.
The trench can be partly backfilled at this point. The trench must be compacted as it is filled, and of course the best tool for the job is the 'hoe pack'. The machine is so powerful the reverberations of the tool can be felt much like an earthquake for a wide area around the operator. The machine is also able to span the trench to allow it to fill the trench and compact it quickly. The operator is highly skilled and crosses the trench repeatedly and can change tools at the end of the arm of the machine - hands free.
This excavator must carefully expose the City water and sewer mains, not damage them while doing so, and remove enough material that the remainder is easily hand dug. The work is efficiently staged such that one pipe is being exposed while the other is being covered. All of this is happening in a manner that makes it look easy, but we are pretty confidant this is not at all easy, particularly in the way it is done and the pace of completion.
At the far end of the trench the water lines, already bedded in much of the trench, are connected using a wet connect tap to the City main, that remains pressurized at all times.
This tool is used to tap into the City water main. After connecting the water lines, the service is now completely live, and can be covered.
The operator is using the hoe pack to compact the fill material and prepare the road for asphalt.
This has been a brief overview of the install process. There is much more detail to go over but this post is lengthy enough already. This is about the least DIY friendly activity in construction today, but the site manager still has a role to play in making sure the work is done well and the outcome is what was agreed to in the contract. The last role of the site manager is to hand over payment for the work. The job tends to cost between $15,000 and $30,000 depending on the site condition and complexity of the install. We got off pretty easy this time with a bill well under the $20,000 level. Thanks again to Precision Underground for the fine job.