Saturday, July 17, 2010

Milky rain, milky rain

It was raining the other day, and there was this curious milky substance running down the curbside gutter. I followed it back to the source: the road construction sign.

The back of the sign is painted white, and in the rain the paint just washes off.

I wondered if maybe the sign had anti-graffiti treatment on the back, so the paint would not stick.

In the meantime, what does all this while paint do to our sewers?


  1. If it's water-soluble, then it's likely acrylic paint, so it's probably doing the same thing to the sewers as anyone who's painted their house and cleaned their brush. I would imaging that the water treatment plant is more than capable of removing acrylic sludge, as it will eventually form a precipitate and sink.

  2. @whereisian
    I thought that sewer water didn't go through the same treatment as house/sink water does. Isn't that why lots of the grates in the roads have pictures of fish on them?

  3. Sewer water in this neighborhood uses "combined" sewers. So both storm run off and sanitary sewage goes to the sewage treatment plant (good) but when it rains too much it all overflows into the River (bad).

  4. Offtopic, but you seem to know (or know where to find out) so much about Ottawa's infrastructure...

    Have you been able to determine why we have so many manhole covers on our roads, and why they are often in pairs? It seems like there are a ridiculous number. (as a motorcyclist, I have to watch for them - especially when they get wet)

    -- Justin

  5. Re infrastructure: be observant, ask city staff and there are often answers. A bit of engineering at university and a few years studying transportation and land use gave me the basics that dont change.

    As for wo/man/holes (something about that is not quite right...) yup this city sure seems to love them, and the next plague will be an enormous proliferation of utility boxes on poles near corners especially. Safety rules/bending grievences etc leads to everything going into a separate above ground box. Utilities are the next parking lots: they take up so much room there is nothing left there to go to.