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Old 11-10-2017, 08:51 PM   #1
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Plumbing basement waste under slab 4 piece


TD;DR Have I vented the tub and shower correctly? Have a feeling the waste and vent are in the wrong order towards the ejector pump. You're looking at approximately a 12' x 12' area.

I'm planning a new basement bathroom for my tiny 24' x 24' story and a half house. I'm reading the building code act for my area and also learning to use google sketchup. Lots of fun.

I've had professional video inspection of the current soil stack. Plumber said that the cast iron waste pipe to the street is very tight to the slab. Not a good candidate for gravity fed waste from the new bathroom.

Using the building code plus discussion from "venting-toilet-shower-under-slab-194048" thread. Sorry, no links for me. I've roughly laid out a waste and vent system that I believe conforms to code but need some help.

All venting is 2". All under slab waste is 3". All drains except for the toilet is 1.5". The sewage will be pumped and vented into the stack as per manufacturers directions (model currently not chosen but likely 3" and 2"). Vent is to be tied into the soil stack above the first floor flood level.

Next steps are to call the local inspector's office and have a chat about staging this project. It will take me a while to grind through the entire project. Hope to submit the technical plans with a bill of materials to the city for verification of the plumbing system before the spring.
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Old 11-10-2017, 08:56 PM   #2
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Re: Plumbing basement waste under slab 4 piece


Where does the sump eject to? You also need a vent on the sump.
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Old 11-10-2017, 09:14 PM   #3
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Re: Plumbing basement waste under slab 4 piece


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Where does the sump eject to? You also need a vent on the sump.
The plan is to have it eject into the waste stack right next to the sump basin about 1' away.

Just speculating but likely will replace the cast iron stack from above 1st floor flood level down to near floor level in the basement. This will allow tie-in for venting and waste of the sewage basin.
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Old 11-11-2017, 06:06 AM   #4
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Re: Plumbing basement waste under slab 4 piece


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This will allow tie-in for venting and waste of the sewage basin.
I have no expertise on this matter but I think the sewage ejection pit has to be vented separately from main vent.
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Old 11-11-2017, 07:59 AM   #5
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Re: Plumbing basement waste under slab 4 piece


The sump needs two pipes, one for vent, one for sewage.
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Old 11-11-2017, 09:31 AM   #6
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Re: Plumbing basement waste under slab 4 piece


Quote:
Originally Posted by joed View Post
The sump needs two pipes, one for vent, one for sewage.
Agreed. The manufacturers instructions will possibly dictate additional requirements as to how they want this done but in general my previous response is meant to conform to code.

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Originally Posted by hkstroud View Post
I have no expertise on this matter but I think the sewage ejection pit has to be vented separately from main vent.
Can't find this in the ONTARIO Building Code 2012. Here is what I am reading:

7.4.6.3. Sumps or Tanks

(1) Only piping that is too low to drain into a building sewer by gravity shall be drained to a sump or receiving tank.

(2) Where the sump or tank receives sanitary sewage it shall be water and air-tight and shall be vented.

(3) Equipment such as a pump or ejector that can lift the contents of the sump or tank and discharge it into the sanitary building drain or sanitary building sewer shall be installed.

(4) Where the equipment does not operate automatically, the capacity of the sump shall be sufficient to hold at least a 24 hours accumulation of liquid.

(5) Where there is a building trap, the discharge pipe from the equipment shall be connected to the sanitary building drain downstream of the trap.

(6) The discharge pipe from every pumped sanitary sewage sump shall be equipped with a union, a check valve and a shut-off valve installed in that sequence in the direction of discharge.

(7) The discharge piping from a pump or ejector shall be sized for optimum flow velocities at pump design conditions.

(8) The discharge pipe from every pumped storm sewage sump shall be equipped with,
(a) a union and a check valve installed in that sequence in the direction of discharge and pumped to above grade level, or
(b) a union, a check valve and a shut-off valve installed in that sequence in the direction of discharge.

No other requirements are listed.

Do you mean the sewage ejection system should be tied into the main stack vent separately from the vent shown in the diagram?

I could be wrong but my assumption is that all venting for the household can be tied into the existing main vent. We're talking about a kitchen sink, main floor three piece bathroom, laundry, and proposed basement bathroom. I can test this assumption against all of the venting requirements but my assumption is a separate vent poking through the roof is not necessary.
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Old 11-16-2017, 12:21 PM   #7
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Re: Plumbing basement waste under slab 4 piece


Quote:
Originally Posted by joed View Post
The sump needs two pipes, one for vent, one for sewage.
This is how I would likely vent a sewage ejector into the main stack.

I'm comparing the cost of an ejector solution to gravity fed. The gravity fed requires that the initial section of horizontal pipe at the base of the stack be deep enough to collect waste from the new bathroom which requires 3.5" drop.

Video inspection suggests gravity fed may not have enough drop and I think the plans are as optimized as possible for 3" waste pipe given my knowledge.

The gravity fed system is the much better option all round. It may be worth excavating a small section just to confirm, or rent a line locator to determine depth. Not certain how accurate these devices are in practice.

I need to talk to the inspector for my area to see what he thinks.

P.S. As you can see Sketchup Make 2017 (free) is useful when mapping out a plumbing system. The 3D Warehouse library is a pain and likely not accurate. No vendors that I have used support Sketchup.
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Old 11-16-2017, 05:18 PM   #8
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Re: Plumbing basement waste under slab 4 piece


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Originally Posted by hkstroud View Post
I have no expertise on this matter but I think the sewage ejection pit has to be vented separately from main vent.
Well, I was wrong. There were additional requirements for venting a sewage sump:

7.5.7.7. Vents for Sanitary Sewage Sumps or Tanks, Dilution Tanks and Macerating Toilet Systems

(1) Except as provided in Sentences (2) and (3), the minimum size of the vent pipe for a sanitary sewage sump or tank, or dilution tank shall be one size smaller than the size of the largest branch or fixture drain draining to the sump or tank.

(2) The size of every vent pipe for a sanitary sewage sump or tank, or dilution tank shall be not less than 2 in., but need not be greater than 4 in.

(3) The size of every vent pipe for a macerating toilet system with a sump or tank shall be not less than 1 in.

This says a 2" vent will be sufficient since the largest fixture drain is for a 3" toilet and the next size smaller is 2". This also meets code for (2) and (3).
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