I just finished a midnight run of the sewer system in one of our local communities, part of a larger project I am working on. The concept behind the midnight run is to look into the sewer system between midnight and 5 am, when flows should be at their minimum to see if we can find where groundwater is entering the system. This should occur AFTER the surface has been sealed via smoke testing, manhole chimney seals and dishes. That way standing water cannot get into the system. These tasks were completed just after Thanksgiving. The question is what we will find. It also rained Saturday so the groundwater table was higher (I prefer October when the groundwater is highest, but you can’t always get that). And a cold front went through with that rain, so the temperatures were in the mid-40s and the skies were clear. So over two nights, under clear skies and shining stars, and a crescent moon, what did we find?
- 4 rats – one ran across the pavement and jumped into the manhole when we opened it. Going home I guess. All were fairly small
- Lots of cockroaches, but not as many as expected – and you wonder from where they get into your house?
- Fatbergs caused by way to much grease going down the drain, mostly from cooking – you do NOT put grease down the sink people!
- Paper towels – also – these do not go down the toilet!
- More grease – see above except this was different cooking grease – yes we can tell who lives where the sewers are by the grease
- Handi-wipes and diapers – exactly how these flush is unclear
- Clothing – this was a commercial laundry. So I guess the sock elves really do live in your washer
- A gold watch or bracelet – we didn’t try to figure out which. Even after our accompanying police officer asked if we could have gotten it out.
- More grease – only this time is was more like auto grease mixed with paint
- The usual feminine hygiene products – none of them should go down the toilet regardless what the box says, esp. applicators which are plastic, not paper! Plastic does not degrade in a sewer plant. In fact it floats. Somebody has to scoop them all off the top of the clarifier. Ditto anything with strings that get wound around pumps
- Adult diapers? Bad enough, and inappropriate with babies, but seriously?
This community is not alone. Most wastewater collection systems (and plants) see these kinds of issues. Paper towels, handi-wipes, and cloth will congeal with the grease and cause blockages. We saw manholes where we could not really see the bottom because of the fatbergs or heavy grease on the bottom (some grease was black and some tan/white). There were rings of grease buildup around manholes and lift stations. Blockages will occur.
Cloth that manages to get through the piping will get caught in the pumps at the lift stations, binding them up and burning them out. One city I work with had an issue where the pumps got bound up every three days because of fancy paper towels (with cloth fibers to make them soft) being flushed down the toilets. Thousands of dollars each time. Finally the restaurant was told they would be getting the bill once we figured out the culprit. They changes the paper towels.
Cloth and too much fat are not biodegradable so must be skimmed off the clarifier at the wastewater plant along with floating objects. That is a fun job. Or I have an example of an equalization basin with floating grease lands, complete with plants. Grease creates issues everywhere it goes – and it goes everywhere.
Clearly education is needed, but many public officials and members of the public do not want to talk about waste, wastewater and personal habits. But we need to have a conversation about the sewer system, and an ongoing one. These problems cost money. Rats and roaches will be ever present, but the populations can be controlled (they like the grease, but not too much). Grease, fibers, plastic and such are not good for operation of the sewer system – it will cost money to remove the clogs and fix the pumps.
Now about that gold watch/bracelet…..