My mom's house in SE Pennsylvania has a vent system that I am not familiar with and I am hoping for some advice to see if there are some alternatives to try before excavating the pipe in question.
Every house along my Mom's steet has a vent cap between the curb and the sidewalk. The toilets at her place have to be flushed several times and/or plunged in order to get solids through. A sewer cleaning service visited the house and based on what they observed, they started snaking via what they referred to as the "street vent." They could get no further than about 6'. Apparently there is something wedged in the trap that they can't get out. They did get out two bricks and a bunch of stones so they think there is more of the same blocking the trap. The city came out and replaced the vent cap and part of the line, but said the problem extends onto the property. [fyi, a neighbor's kid dumped the stones through the vent cap holes, but I don't understand the bricks]
What is the purpose of a vent line with a trap that runs to the street? Is it possible that the vent pipe that goes to the roof is sufficient and the real problem is a blocked drainage line? When the sewer cleaners talked about a "vent line" is it possible that this is also the same as the drainage line?
Is it worthwhile to pay (~$350) for the sewer cleaning company to return and clean the drain lines and/or roof vent before paying a plumber to dig up the buried vent line and trap (~$1500?). Thanks for any insights.