I have a small retail proerty, for which we periodically hydrojet the sewer line as preventive maintenance. There is a Chinese Restaurant and, despite proper care of their grease trap, the sewer line plugs periodically, hence the preventive maintenance.

We have had the sewer line videod, and found no problem.

Now, on a couple of occasions, they did the hydrojet preventive maintenance. Within a couple of days, a clog presented itself, and they had to hydrojet again.

Why would a sewer line that is not clogged, although presumably becoming a bit slow, end up with a clog a couple of days after this preventive maintenance?

Thanks.

If it is a bit slow chances are that there is an obstruction somewhere. The jetting may have broken it loose but not flushed it totally away. I am sure surprised that the camera did not show a plug or any reason for the slow drain. How far did the plumber go with the camera, hopefilly all the way to the city riser.

Televise it after they hydro jet the line.
Grease is the hardest thing to manage in a sewer line and Chineese Restaurants are notorious for problems.
I have had them plug main lines in the street from the grease.
Televise after they have used there hydrojet and you will see grease stuck to the pipe.
You may need to clean the grease traps more often.
I agree with Ballenger they probably just knocked the grease of the sides of the pipe.
If your going to do routine maintenance anyway try rodding the line with a grease paddle. Most plumber should know what they are and they will be a lot cheaper than a hydro jet.

I had a blockage in a restaurant kitchen drain that was loaded with grease. Couldn't auger it out, couldn't blow it out, I ended up renting a steam jenny and taking the jenny up on the roof and sending steam down the vent. This loosened the grease and let it flow into the grease trap. Regards, Tom

Good idea. I have thought about trying this on lines that run directly into a manhole.
From what the original post said I understood the blockage was past the grease trap.
Would be interesing to see if it causes a problem when the grease hits the main and solidifies again.
There are some degreasing products that work well in the mains. I will get the product information from work today and post them later.

Quote:

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Originally Posted by acmepinnacle

I have a small retail proerty, for which we periodically hydrojet the sewer line as preventive maintenance. There is a Chinese Restaurant and, despite proper care of their grease trap, the sewer line plugs periodically, hence the preventive maintenance.

We have had the sewer line videod, and found no problem.

Now, on a couple of occasions, they did the hydrojet preventive maintenance. Within a couple of days, a clog presented itself, and they had to hydrojet again.

Why would a sewer line that is not clogged, although presumably becomming a bit slow, end up with a clog a couple of days after this preventive maintenance?

thanks.

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Is the grease trap draining everything in the kitchen, or is it draining only the fixtures required by local code?

I've been in a few kitchens where everything, including the hand sinks and dishwasher were plumbed into the grease trap, which overwhelms the grease trap.

Also, I've seen a number of grease traps improperly maintained; Are they cleaning out the flow control? Are they cleaning out the non-grease sludge that accumulates at the bottom of the interceptor? Have they disconnected and capped the vent on the flow control -- Or was it ever vented in the first place?

Jetting works best going upstream toward the building, that way as it moves up the pipe toward the building it is flushing everything toward the city sewer. Not all buildings have an outside cleanout and you have no choice but to start inside and go toward the street, this leaves some buildup in the line that can create a clog later. We use a flusher nozzle that creates a lot of flow as a last step to prevent this from happening.