My contractor recently installed a sewage ejector pump for a new basement bathroom that will feed waste to a septic tank. The pump will be handling a toilet, shower, and two sinks. I have some concerns about the venting set-up he installed and would like to know
I have included photos for reference. Please ignore all of the laundry room hoses/vents around it; they are not part of the set-up. The vent is labeled INLINE VENT RC-390.
This AAV would work for "negative" pressure when the pump kicks on, air would come in through it. When the pump kicks off and water falls back down the pipe (a "positive" pressure), the AAV wouldn't let any air out, so the pressure might blow some bubbles back up into the appliances, or maybe it wouldn't since there's so little due to that check valve. Maybe not a deal breaker, you could ask an inspector if it's up to code.
The "normal" way is a normal vent, there are other kind of whacky work arounds where the vent line ties back into the drain line itself. https://ipsplumbingproducts.com/wp-content/uploads/2020/07/Studor-Sump-Pump_071420.pdf
I see two code violations there.
If your using the International Residential Code (IRC) sect. p3114.8 prohibits the use of AA valves unless designed by an engineer (might be acceptable to your inspector if the manufacturer says it works with their system).
The discharge pipe needs a full open valve to close off the pipe above the backflow preventer when it eventually needs repair (IRC sect. P3007.2). Otherwise all the sewage in the pipe above the backflow will dump out when you cut the pipe.
You basically have a mini septic tank in your basement. Septic tanks are stinky and you definitely want this sealed up nice and tight so you don't smell it. However, when you pump it out with the rest of the sewage, you need to replace the space the sewage took with air. Since it's sealed up nice and tight, there is no way for air to get in. This is what your "INLINE VENT RC-390" is for. You can see the part here, it is a Pro Vent ABS Automatic Vent Plumbing Air Admittance. Its purpose is to allow air to enter the tank when there is negative pressure (when it's pumping), and keep air in the tank when there is not negative pressure.
When you ask if it is safe, I assume you are thinking since it has the word VENT on it, that it will vent out gases, but that is not the case. It only allows air to enter, not exit. The alternative is to run a vent pipe to tie into the other vent pipes, which can be costly depending on where the vent pipe has to be routed.
